Abstrict A method for controlling, according to the L-jetronic fuel injection
principle, an internal combustion engine with a fuel injection valve
fitted to its intake manifold, and an intake air flow meter. Repeatedly
a first quantity representing the desired amount of fuel to be provided
to the combustion chambers of the engine during the time period
between the next two fuel injection pulse time points is determined,
based upon sensed values of certain operational parameters including
intake air flow, and a second quantity is determined as the time
smoothed value of the first quantity. Optionally further the second
quantity may be modified according to engine operational parameters.
Simultaneously, at proper injection time points in the engine's
operational cycle, the fuel injection valve is opened for a time
corresponding to a third quantity which is calculated from the second
quantity. A device is also explained, incorporating an electronic
computer, which practices this method. Thereby, overshooting of
the air flow meter is corrected for.
Claims What is claimed is:
1. In an internal combustion engine comprising an intake manifold,
a fuel injection valve fitted to said intake manifold and adapted
to be selectively opened so as to inject fuel into said intake manifold
by supply of an actuating signal thereto for a time duration corresponding
to that of said actuating signal supplied, and an intake air flow
meter of a type having a swingable flapper adapted to be swung by
intake air flow for angles corresponding to flow rates of intake
air, said intake air flow meter generating an intake air flow rate
signal representative of intake air flow rate,
a method of controlling fuel injection by said fuel injection valve,
comprising the repetitive steps of:
(a) sensing revolution of said engine with an engine revolution
sensor so as to generate an engine revolution signal representative
of revolutionary speed of said engine;
(b) determining at a sequence of instants separated by successive
intervals successive values of a first quantity which is proportional
to said intake air flow rate signal and inversely proportional to
said engine revolution signal;
(c) determine at said sequence of instants a second quantity which
is a sum of a value of said first quantity at an immediately preceding
instant to a current instant of said sequence and a predetermined
fraction of a difference between said current instant value of said
first quantity and said value of said first quantity at said immediately
preceding instant to said current instant; and
(d) generating said actuating signal to be supplied to said fuel
injection valve according to said second quantity, each current
rate of time duration in which said actuating signal is supplied
to said fuel injection valve being substantially proportional to
each current value of said second quantity.
2. In an internal combustion engine comprising an intake manifold,
a fuel injection valve fitted to said intake manifold and adapted
to be selectively opened so as to inject fuel into said intake manifold
by supply of an actuating signal thereto for a time duration corresponding
to that of said actuating signal supplied, and an intake air flow
meter of a type having a swingable flapper adapted to be swung by
intake air flow for angles corresponding to flow rates of intake
air, said intake air flow meter generating an intake air flow rate
electrical signal representative of intake air flow rate, a fuel
injection control device, comprising:
(a) an engine revolution sensor for repeatedly responding to revolution
of said engine and for producing an engine revolution electrical
signal representative of revolutionary speed of said engine;
(b) an electronic computer for receiving supply of said intake
air flow rate electrical signal and said engine revolution electrical
signal, said electronic computer including means for:
(i) determining at a sequence of instants separated by successive
intervals successive values of a first electrical quantity which
is proportional to said intake air flow rate electrical signal and
inversely proportional to said engine revolution electrical signal;
and
(ii) determining at said sequence of instants a second electrical
quantity which is a sum of a value of said first electrical quantity
at an immediately preceding instant to a current instant in said
sequence and a predetermined fraction of a difference between said
current instant value of said first electrical quantity and said
value of said first electrical quantity at said immediately preceding
instant to said current instant; and
(c) an interface device which converts said second electrical quantity
to said actuating signal supplied to said fuel injection valve to
cause it to open for a period corresponding to said value of said
second electrical quantity to pass therethrough fuel to be injected
into said intake manifold.
3. The method of controlling fuel injection according to claim
1 further comprising the repetitive steps of:
(e) determining at said sequence of instants each current amount
of fuel caught as adhered onto an inner wall surface of said intake
manifold according to each current value of said second quantity,
and each current value of fuel thus accumulated on said inner wall
surface of said intake manifold; and
(f) determining at said sequence of instants each current amount
of fuel carried by intake air flow off from fuel accumulated on
said inner wall surface of said intake manifold according to each
current amount of fuel accumulated on said inner wall surface of
said intake manifold;
wherein generation of said actuating signal is modified so that
each current rate of time duration in which said actuating signal
is supplied to said fuel injection valve is substantially proportional
to each current value of said second quantity and is further increased
by an amount corresponding to each current amount of fuel caught
as adhered onto said inner wall surface of said intake manifold
and is further decreased by an amount corresponding to each current
amount of fuel carried by intake air flow off from fuel accumulated
on said inner wall surface of said intake manifold.
4. A method of controlling fuel injection according to claim 3
further comprising repetitively:
(g) sensing an intake air temperature by an intake air temperature
sensor to generate an intake air temperature signal, wherein said
second quantity is further modified by said intake air temperature
signal.
5. A method of controlling fuel injection according to claim 3
further comprising repetitively:
(g) sensing oxygen content in gases exhausted from said engine
by an oxygen sensor to generate an excess air signal, wherein said
second quantity is further modified by said excess air signal.
6. A method for controlling fuel injection according to claim 3
further comprising repetitively:
(g) sensing temperature of said engine by an engine temperature
sensor to generate an engine temperature signal, wherein said second
quantity is further modified by said engine temperature signal.
7. A fuel injection control device according to claim 2 wherein
said electronic computer further includes means for determining
at said sequence of instants each current amount of fuel caught
as adhered onto an inner wall surface of said intake manifold according
to each current value of said second electrical quantity and each
current value of fuel thus accumulated on the inner wall surface
of said intake manifold, for determining at said sequence of instants
each current amount of fuel carried by intake air flow off from
fuel accumulated on said inner wall surface of said intake manifold
according to each current amount of fuel accumulated on said inner
wall surface of said intake manifold, and for modifying said second
electrical quantity so that said second electrical quantity is increased
by an amount corresponding to each current amount of fuel caught
as adhered onto said inner wall surface of said intake manifold
and is decreased by an amount corresponding to each current amount
of fuel carried by intake air flow off from fuel accumulated on
said inner wall surface of said intake manifold.
8. A fuel injection control device according to claim 2 further
comprising:
(d) an intake air temperature sensor which responds to temperature
of engine intake air and generates an intake air temperature electrical
signal, wherein said electronic computer further modifies said second
electrical quantity by said intake air temperature electrical signal.
9. A fuel injection control device according to claim 2 further
comprising:
(d) an oxygen sensor which responds to oxygen content in gases
exhausted from the engine and generates an excess air electrical
signal, wherein said electronic computer further modifies said second
electrical quantity by said excess air electrical signal.
10. A fuel injection control device according to claim 2 further
comprising:
(d) an engine temperature sensor which responds to engine temperature
and generates an engine temperature signal, wherein said electronic
computer further modifies said second electrical quantity by said
engine temperature electrical signal.
Description BACKGROUND OF THE INVENTION
The present invention relates to a control device and method for
an internal combustion engine equipped with a fuel injection system;
and more particularly relates to a control device, incorporating
a plurality of sensors and an electronic control computer which
receives signals from said sensors and which controls said fuel
injection system of said internal combustion engine, said control
device accurately and appropriately controlling the amount of fuel
supplied by said fuel injection system during various and diverse
operational conditions of the internal combustion engine so as to
provide good engine operational characteristics, and to a control
method for said internal combustion engine equipped with a fuel
injection system, said control method being practiced by said device.
Fuel injection is becoming a more and more popular method of fuel
supply to gasoline internal combustion engines of automotive vehicles
nowadays. This is because of the inherently greater accuracy of
metering of liquid fuel by fuel injection techniques as opposed
to the metering of liquid fuel available in a carburetor type fuel
supply system. In many cases the advantages obtained by this greater
accuracy of fuel metering provided by a fuel injection system outweigh
the disadvantage of the increased cost thereof. For example, this
better fuel metering enables engine designers to produce engines
with higher compression ratio and more spark advance, which can
lead to increased performance characteristics, such as increased
power, increased torque, and better engine elasticity.
Because a fuel injection system can accurately determine the amount
of fuel to be supplied to the airfuel mixture intake system of the
vehicle in a wide variety of engine operational conditions, it is
possible to operate the engine in a way which generates substantially
lower levels of harmful exhaust emissions such as NOx, HC, and CO;
and in fact it is possible to satisfy the legal requirements for
cleanliness of vehicle exhaust, gases, which are becoming more and
more severe nowadays, without providing any exhaust gas recirculation
for the engine. This is very beneficial with regard to drivability
of the engine, especially in idling operational condition. Further,
because of the higher efficiency of fuel metering available, this
allows leaner airfuel mixture operation of the engine with still
acceptable drivability. With fuel injection provided to a vehicle
type, more consistent exhaust emission results are available from
vehicles coming off the assembly line at the factory, without complicated,
troublesome, and expensive individual adjustments. Further, the
warmup control of the vehicle is highly flexible, i.e. can be flexibly
adjusted to a wide variety of engine warming up conditions, which
contributes considerably to the achieved exhaust emission results.
Further, an internal combustion engine equipped with a fuel injection
system can be operated in such a way as to be substantially more
economical of gasoline than a carburetor type internal combustion
engine. This is again because of the greater accuracy available
for determination of the amount of fuel to be supplied to the intake
system of the vehicle over a wide variety of engine operational
conditions. Since it is possible to operate the engine at the stoichiometric
air/fuel ratio, and to apply closed loop control to the fuel injection
control system, it is possible to reduce the amount of spark retardation,
and also the above mentioned dispensing with exhaust gas recirculation
is possible, and both of these have significant beneficial effects
with regard to fuel consumption. Further, with a fuel injection
type fuelair mixture supply system, it is possible to cut off fuel
supply entirely when the engine is operating in an overrun mode,
which again results in a significantly reduced consumption of fuel.
Nowadays, with the increased cost of fuel and the wider demand for
fuel economical vehicles, and with legal requirements which are
being introduced in some countries relating to fuel economy of automotive
vehicles, these considerations are more and more becoming very important.
In addition, by the introduction of a fuel injection type fuel-air
mixture supply system, a engine of smaller piston displacement can
replace an engine with larger piston displacement which is provided
with a carburetor type fuel supply system, while providing the same
output power, and again this reduces fuel consumption. By the introduction
of a fuel injection type fuel-air mixture supply system, also, in
many cases it is possible to switch an engine from premium grade
type fuel operation to operation on lower grade or regular type
fuel, while still providing the same output power, which is economical
of the more expensive premium grade type fuels.
Some types of fuel injection system for internal combustion engines
utilize mechanical control of the amount of injected fuel. An example
of this mechanical fuel amount control type of fuel injection system
is the so called K-jetronic type of fuel injection system. However,
nowadays, with the rapid progress which is being attained in the
field of electronic control systems, various arrangements have been
proposed in which electronic control circuits make control decisions
as to the amount of fuel that should be supplied to the internal
combustion engine, in various engine operational conditions. Such
electronic fuel injection systems are becoming much more popular,
because of the more flexible way in which the fuel metering can
be tailored to various different combinations of engine operational
conditions. The most modern of these electronic fuel injection systems
use a microcomputer such as an electronic digital computer to regulate
the amount of fuel injected per one engine cycle, and it is already
conventionally known to use the microcomputer also to regulate various
other engine functions such as the provision of ignition sparks
for the spark plugs.
In an electronic fuel injection system, the control system requires
of course to know the moment by moment current values of certain
operational parameters of the internal combustion engine, the amount
of injected fuel being determined according to these values. The
current values of these operational parameters are sensed by sensors
which dispatch signals to the electronic control system via A/D
converters and the like. In such an arrangement, electric signals
are outputted by such an electronic control system to an electrically
controlled fuel injection valve, so as to open it and close it at
properly determined instants separated by proper time intervals;
and this fuel injection valve is provided with a substantially constant
supply of pressurized gasoline from a pressure pump. This pressurized
gasoline, when the fuel injection valve is opened, and during the
time of such opening, is squirted through said fuel injection valve
into the intake manifold of the internal combustion engine upstream
of the intake valves thereof. Thus, the amount of injected gasoline
is substantially proportional to the time of opening of the fuel
injection valve, less, in fact, an inoperative time required for
the valve to open. Sometimes only one fuel injection valve is provided
for all the cylinders of the internal combustion engine, or alternatively
several fuel injection valves may be provided, up to one for each
cylinder of the engine, according to design requirements.
The first generation fuel injection systems were of the so called
D-jetronic type, in which the main variables monitored by the electronic
fuel injection control system are the revolution speed of the internal
combustion engine and the vacuum, or depression, present in the
intake manifold of the internal combustion engine downstream of
the throttle valve mounted at an intermediate position therein due
to the suction in said intake manifold produced by the air flow
passing through the intake manifold of the internal combustion engine
to enter the combustion chambers thereof after being mixed with
liquid fuel squirted in through the fuel injection valve or valves.
From these two basic measured internal combustion engine operational
parameters, a basic amount of gasoline to be injected into the intake
system of the internal combustion engine is determined by the control
system, and then the control system controls the fuel injection
valve so as to inject this amount of gasoline into the engine intake
system. Other variables, such as intake air temperature, engine
temperature, and others, are further measured in various implementations
of the D-jetronic system and are used for performing corrections
to the basic fuel injection amount.
Following this, a second generation of fuel injection systems has
been developed, which is of the so called L-jetronic type, in which
the main variables monitored by the electronic fuel injection control
system are the revolution speed of the internal combustion engine
and the amount of air flow passing through the intake manifold of
the internal combustion engine to enter the combustion chambers
thereof after being mixed with liquid fuel squirted in through the
fuel injection valve or valves. This air flow amount is measured
by an air flow meter of a design which has become developed, located
at an intermediate point in the intake manifold. From these two
basic measured internal combustion engine operational parameters,
again a basic amount of gasoline to be injected into the intake
system of the internal combustion engine is determined by the control
system, and then the control system controls the fuel injection
valve so as to inject this amount of gasoline into the engine intake
system. Other variables, such as intake air temperature, engine
temperature, and others, are again further measured in various implementations
of the L-jetronic system, and are used for performing corrections
to the basic fuel injection amount. This L-jetronic fuel injection
control system is currently well known and is nowadays fitted to
a large number and variety of vehicles.
One refinement that has been made to the L-jetronic fuel injection
system has been to perform a control of the fuel injection amount
based upon feedback from an air/fuel ratio sensor or O2 sensor,
which is fitted to the exhaust manifold of the internal combustion
engine and which detects the concentration of oxygen in these exhaust
gases, again in a per se well known way. This feedback control homes
in on a proper amount of fuel injection, so as to provide a stoichiometric
air/fuel ratio for the intake gases sucked into the cylinders of
the engine, and for the exhaust gases of the engine, but the starting
point region over which the homing in action of such a feedback
control system is effective is limited, and therefore the determination
of the approxmately correct amount of fuel to be injected by the
fuel injection valve is still very important, especially in the
case of transient operational conditions of the engine.
A typical kind of air flow meter that is used in the L-jetronic
system of fuel injection engine control system is illustrated in
sectional view in FIG. 3 of the appended drawings. Such an air flow
meter has a flapper element, biased in the rotational direction
to obstruct the air intake passage, which is thus displaced in the
opposite rotational direction according to the air flow amount that
is being aspired into the internal combustion engine. The movement
of this flapper element is sensed by some sensing system such as
a potentiometer, and is damped by some damping system such as for
example the one shown in the figure, which is a pneumatic type damping
system.
A difficulty that has occurred with such a type of air flow meter
is that such a flapper element tends to overshoot its proper position
during the initial phase of sharp acceleration of the internal combustion
engine, so that at this time the above mentioned air intake flow
amount sensing system such as a potentiometer indicates, for a short
transient time immediately after start of acceleration, a substantially
greater value for intake air amount than the correct amount. It
will of course be appreciated by those skilled in the art that,
if the amount of fuel injected through the fuel injection valve
into the intake manifold is based directly upon this erroneous signal
provided by the overshooting flapper element which actuates the
above mentioned air intake flow amount sensing system such as a
potentiometer, then during this overshooting time, just after the
start of engine acceleration, too much fuel will be supplied to
the internal combustion engine, and a rich spike will be caused
in the air-fuel mixture supplied to said engine. This will cause
considerable variation of the acceleration being provided by the
internal combustion engine, i.e. will cause jerk or torque shock
during the initial phase of acceleration. Further, it has been found
that merely increasing the amount of damping of the movement of
the flapper element provided by said damping means such as a pneumatic
damping system is not adequate to solve this problem, since over
damping of the movement of said flapper element is unduly restrictive
of its movement. This rich spike in the the air-fuel mixture supplied
to said engine dies away quickly with time, after the initial start
of acceleration.
Another difficulty that has occurred with such normal spark ignition
engines which are equipped with the L-jetronic form of electronic
fuel injection system is that, if the fuel injection system calculates
the amount of fuel which it is desired to inject into the combustion
chambers of the engine in the next pulse of fuel injection, and
then simply controls the fuel injection valve or valves in the engine
air intake system so as to inject this amount of fuel into the air
intake system on this next fuel injection pulse, the engine will
be substantially properly operated during steady operational conditions,
but during the initial phase of acceleration the engine will not
receive the proper amount of fuel, because of the effect of fuel
adhering to the wall surfaces of the air intake passage and of the
intake ports of the engine.
Considering this phenomenon in more detail, since in such a L-jetronic
fuel injection system the supply of liquid fuel is not vaporized
or finely atomized as in a carburetor type fuel supply system, but
is squirted directly into the air intake passage of the engine through
the fuel injection valve which cannot atomize the fuel very well,
therefore quite a large quantity of liquid fuel tends to accumulate
in liquid form on the wall surfaces of the air intake passage and
of the intake ports. Of course, also some of this liquid fuel tends
to get swept off or sucked off these wall surfaces into the combustion
chambers of the engine. In completely steady state operation of
the engine, these two effects, i.e. the fuel accumulation or adhering
effect and the fuel sucking off effect, tend to cancel one another
out. However, during rapidly changing operational conditions of
the engine, such as sharp acceleration of the engine, these two
effects by no means cancel one another out, and prior art types
of fuel injection systems in which no consideration was given to
the effect of adhesion of fuel on the wall surfaces of the air intake
passage and of the intake ports, and the effect of sucking off of
said fuel, are not able to provide proper operation of the internal
combustion engine, during such sharp acceleration conditions.
In detail, in the prior art type of fuel injection system in which
no consideration is given to the effect of adhesion of fuel on the
wall surfaces of the air intake passage and of the intake ports,
and to the effect of sucking off of said fuel, when the engine is
accelerated of course the throttle valve in the air intake system
is opened, and together with this the amount of fuel being injected
through the fuel injection valve is simultaneously increased; but,
because a substantial proportion of this extra injected fuel is
adhered or accumulated in the liquid layer or film on the wall surfaces
of the air intake passage and of the intake port, thus increasing
the total volume of fuel in this liquid layer or film, thereby the
air-fuel mixture actually being supplied into the combustion chambers
of the internal combustion engine becomes over lean; in other words,
a lean spike of air-fuel mixture occurs during engine acceleration,
in fact somewhat after the start of such acceleration.
An aggravating factor with regard to these two problems during
engine acceleration, i.e. the problem of the occurrence of an initial
rich spike of air/fuel ratio caused by overshooting of the air flow
meter, and the problem of the occurrence of a somewhat delayed lean
spike of air/fuel ratio caused by accumulation of fuel in the liquid
layer or film on the wall surfaces of the air intake passage and
of the intake port, is due to the timing of these spikes. In fact,
the first rich spike due to overshooting of the air flow meter tends
to occur just before the second lean spike due to adherence of fuel
to said wall surfaces, and the combined or synergistic effect of
these two contrary spikes tends to produce a much worse jerking
performance of the internal combustion engine during acceleration,
than would occur because of either the rich spike or the lean spike,
on its own.
This effect is illustrated in FIGS. 8 and 9 of the appended drawings.
FIG. 8 is a time chart, in which air/fuel ratio of air-fuel mixture
actually delivered to the combustion chambers of the internal combustion
engine is shown on the ordinate and time is shown on the abscissa,
showing by the single dotted line the behavior of variation of air/fuel
ratio of the air-fuel mixture of an engine with a fuel injection
system controlled according to a prior art method of engine control,
during an engine operational episode involving sharp acceleration.
This figure illustrates that during steady operation of the internal
combustion engine the air/fuel ratio of the air-fuel mixture in
this engine controlled in a prior art fashion is substantially stoichiometric,
but that during sharp acceleration of the engine the air/fuel ratio
of the air-fuel mixture in this engine controlled in such a prior
art fashion deviates substantially from stoichiometric first towards
the rich side and then immediately subsequently towards the lean
side, i.e. undergoes in rapid succession first a rich spike and
then a lean spike. Further, FIG. 9 is a time chart, in which vehicle
acceleration is shown on the ordinate and time is shown on the abscissa,
said abscissa corresponding to and indicating the same time as the
abscissa of FIG. 8 showing by the dashed line the behavior of variation
of vehicle acceleration of said vehicle incorporating said internal
combustion engine with a fuel injection system controlled according
to said prior art method of engine control, during the same sharp
acceleration engine operational episode as the engine operational
episode illustrated in FIG. 8. This figure shows that when this
vehicle incorporating this internal combustion engine with a fuel
injection system controlled according to said prior art method is
sharply accelerated, it undergoes very sharp variation of acceleration,
i.e. jerk or lurching, which is very uncomfortable for riders in
the vehicle, and reduces vehicle drivability, as well as impairing
durability of the engine and of the transmission of the vehicle,
which transmits the power of said engine to the road surface. Further,
the presence of the above described rich spike and of the above
described lean spike of air/fuel ratio of the air-fuel mixture supplied
to the combustion chambers of the internal combustion engine are
liable to cause problems with regard to meeting the ever more strict
standards with regard to purification of the exhaust gases of the
internal combustion engine.
In order to investigate the problems with regard to the amount
of fuel adhering to the wall surfaces of the intake manifold and
the intake ports, one of the present inventors, together with another,
has carried out various experimental researches relative to the
behavior of fuel, both in its adhering to said wall surfaces of
the air intake passage and of the intake ports, and in its being
sucked off from said wall surfaces by the air flowing therepast,
so as to enter into the combustion chambers of the engine. Some
of the results of these experimental researches may be summarized
as follows. The amount of fuel out of one pulse of fuel injection
provided through the fuel injection valve which adheres to the wall
surfaces of the air intake passage and of the intake ports, so as
to be added to the cumulative amount of fuel already there, is,
other things being equal, roughly proportional to the total amount
of fuel in said fuel injection pulse; in other words, substantially
the same proportion of the injected fuel tends to adhere to said
wall surfaces, irrespective of the actual amount of injected fuel.
The proportionality constant relative to this adhesion, however,
tends to vary with variation of, in particular, the following quantities:
air intake manifold pressure or depression, engine cooling water
temperature, engine revolution speed, and air flow speed in the
air intake manifold. As a matter of fact, said proportionality constant
varies, to a lesser extent, with intake passage wall temperature
and intake air temperature and atmospheric pressure. Further, the
absolute amount of fuel out of the total or cumulative amount of
fuel which is adhering to the wall surfaces of the air intake passage
and of the intake ports which is sucked off into the combustion
chambers of the internal combustion engine is, other things being
equal, roughly proportional to said total or cumulative amount of
fuel adhering to the wall surfaces of the air intake passage and
of the intake ports; in other words, substantially the same proportion
of the fuel adhering to the wall surfaces tends to be sucked off,
irrespective of the actual amount of adhering fuel. The proportionality
constant relative to this sucking off, however, again tends to vary
with variation of the following quantities: air intake manifold
pressure or depression, engine cooling water temperature, engine
revolution speed, and air flow speed in the air intake manifold.
Again, as a matter of fact, said proportionality constant varies,
to a lesser extent, with intake passage wall temperature and intake
air temperature and atmospheric pressure. Further details of these
experimental researches performed by the present inventor, and another,
with respect to these proportionality constants will be found later
in the section of this specification entitled "DESCRIPTION
OF THE PREFERRED EMBODIMENT".
SUMMARY OF THE INVENTION
Accordingly, it is the primary object of the present invention
to provide a method for controlling an internal combustion engine
which is equipped with an electronic fuel injection system, and
a device which implements the method, which take account of this
overshooting of the air flow meter during sharp acceleration of
the engine.
It is a further object of the present invention to provide such
a method for controlling an internal combustion engine which is
equipped with an electronic fuel injection system, and a device
which implements the method, which avoid fluctuations in the air/fuel
ratio of the air-fuel mixture being supplied to the combustion chambers
of the engine, due to this overshooting of the air flow meter during
sharp acceleration of the engine.
It is a further object of the present invention to provide such
a method for controlling an internal combustion engine which is
equipped with an electronic fuel injection system, and a device
which implements the method, which during the initial phase of acceleration
of the internal combustion engine when the air flow meter is overshooting
can compensate for this increase so as to avoid a rich spike being
produced in the air/fuel ratio of the air-fuel mixture delivered
to the internal combustion engine.
It is a further object of the present invention to provide such
a method for controlling an internal combustion engine which is
equipped with an electronic fuel injection system, and a device
which implements the method, which do not require the provision
of any very complicated means for determining the air intake amount
of the internal combustion engine, but which use the common or conventional
form of air flow meter for this purpose, while avoiding the problems
detailed above with respect to overshooting thereof.
It is a further object of the present invention to provide such
a method for controlling an internal combustion engine which is
equipped with an electronic fuel injection system, and a device
which implements the method, which can provide an air-fuel mixture
of the proper air/fuel ratio, both during steady operation of the
internal combustion engine, and during transient operational conditions
thereof such as acceleration.
It is a further object of the present invention to provide such
a method for controlling an internal combustion engine which is
equipped with an electronic fuel injection system, and a device
which implements the method, which can also properly take account
of the quantity of fuel which is present in said liquid layer or
film on the wall surfaces of the air intake passage and of the intake
ports.
It is a further object of the present invention to provide such
a method for controlling an internal combustion engine which is
equipped with an electronic fuel injection system, and a device
which implements the method, which can also perform a correction
to somewhat increase the basic fuel injection amount provided by
the fuel injection system, during the phase of acceleration of the
internal combustion engine when the amount of fuel which is adhered
in a film to the wall surfaces of the air intake passage and of
the intake ports is increasing, said phase of acceleration occurring
just after the phase of acceleration in which said overshooting
of said intake air flow meter is liable to occur, so as to also
compensate for this increase and so as to avoid a lean spike being
produced in the air/fuel ratio of the air-fuel mixture delivered
to the internal combustion engine during this accelerational phase.
It is a further object of the present invention to provide such
a method for controlling an internal combustion engine which is
equipped with an electronic fuel injection system, and a device
which implements the method, which during acceleration of the internal
combustion engine can avoid the successive production, in the air/fuel
ratio of the air-fuel mixture delivered to the internal combustion
engine, of a rich spike followed by a lean spike.
It is yet a further object of the present invention to provide
such a method for controlling an internal combustion engine which
is equipped with an electronic fuel injection system, and a device
which implements the method, which provide good drivability for
an automotive vehicle incorporating the fuel injection system, especially
during acceleration thereof.
It is yet a further object of the present invention to provide
such a method for controlling an internal combustion engine which
is equipped with an electronic fuel injection system, and a device
which implements the method, which avoid the production of excessive
jerking or acceleration variation during acceleration of an automotive
vehicle incorporating the fuel injection system.
It is yet a further object of the present invention to provide
such a method for controlling an internal combustion engine which
is equipped with an electronic fuel injection system, and a device
which implements the method, which ensure good quality of exhaust
emissions for an automotive vehicle incorporating the fuel injection
system, especially during acceleration thereof.
Of course, the provision of any special sensor for detecting the
actual amount of adhered fuel on the wall surfaces of the air intake
passage and of the intake ports is not practicable: such a sensor,
even if it could be made, would be costly, difficult to make and
install and service, and prone to breakdown during use.
Therefore, it is yet a further object of the present invention
to provide such a method for controlling an internal combustion
engine which is equipped with an electronic fuel injection system,
and a device which implements the method, which do not require any
special sensor for detecting the actual amount of adhered fuel on
the wall surfaces of the air intake passage and of the intake ports.
It is yet a further object of the present invention to provide
such a method for controlling an internal combustion engine which
is equipped with an electronic fuel injection system, and a device
which implements the method, which are not prone to breakdown during
use.
It is yet a further object of the present invention to provide
such a method for controlling an internal combustion engine which
is equipped with an electronic fuel injection system, and a device
which implements the method, which do not involve undue expense
in manufacture of the fuel injection system.
It is yet a further object of the present invention to provide
such a method for controlling an internal combustion engine which
is equipped with an electronic fuel injection system, and a device
which implements the method, which do not involve undue difficulty
in manufacture of the fuel injection system.
It is yet a further object of the present invention to provide
such a method for controlling an internal combustion engine which
is equipped with an electronic fuel injection system, and a device
which implements the method, which do not involve undue difficulty
in maintenance of the fuel injection system.
According to the most general method aspect of the present invention,
these and other objects are accomplished by, for an internal combustion
engine with a combustion chamber system and comprising an air-fuel
mixture intake system comprising an intake manifold, said internal
combustion engine further comprising a fuel injection valve fitted
to said intake manifold which is selectively opened and closed by
selective supply of an actuating signal thereto and which when so
opened injects liquid fuel into said intake manifold, said internal
combustion engine and said fuel injection valve operating according
to an operational cycle: an engine control method, comprising the
processes, repeatedly and alternatingly and/or simultaneously performed,
of: (a) sensing the current values of certain operational parameters
of said internal combustion engine, including sensing the value
of the rate of flow of intake air into said intake manifold by the
use of an intake air flow meter; (b) performing the following processes
in the specified order: (b1) based upon the current values of said
sensed operational parameters of said internal combustion engine,
including the current value of rate of flow of intake air into said
intake manifold, calculating the value of a first quantity representing
the desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points; (b2) updating
the value of a second quantity representing the time smoothed desired
amount of fuel to be provided to said combustion chamber system
of said internal combustion engine during the time period between
the next two fuel injection pulse time points, by adding to said
second quantity representing the time smoothed desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points the value produced by subtracting said
second quantity representing the time smoothed desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points from said first quantity representing
the desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points and multiplying
the result by a constant value less than unity; and (b3) optionally
further modifying said second quantity representing the time smoothed
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points according
to engine operational parameters; and (c) at time points in said
operational cycle of said internal combustion engine and said fuel
injection valve which are proper fuel injection time points, performing
the following processes in the specified order: (c1) modifying said
actuating signal according to the value of a third quantity representing
the actual corrected fuel amount to be injected through said fuel
injection valve in the next fuel injection pulse, said third quantity
representing the actual corrected fuel amount to be injected through
said fuel injection valve in the next fuel injection pulse being
calculated from the current value of said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points;
and (c2) supplying said modified actuating signal to said fuel injection
valve in such a fashion as to cause said fuel injection valve to
open for a time period which will allow an amount of fuel approximately
equal to the fuel amount represented by said third quantity representing
the actual corrected fuel amount to be injected through said fuel
injection valve in the next fuel injection pulse to pass through
said fuel injection valve so as to be injected into said intake
manifold.
According to such a method, by time smoothing the value of said
first quantity representing the desired amount of fuel to be provided
to said combustion chamber system of said internal combustion engine
during the time period between the next two fuel injection pulse
time points in the way outlined to produce said second quantity
representing the time smoothed desired amount of fuel to be provided
to said combustion chamber system of said internal combustion engine
during the time period between the next two fuel injection pulse
time points, whose value thus pursues the value of said first quantity
representing the desired amount of fuel to be provided to said combustion
chamber system of said internal combustion engine during the time
period between the next two fuel injection pulse time points, thereby
fluctuations in the output signal of said intake air flow meter,
due to overshooting thereof during acceleration, can be taken account
of; and thereby occurrence of the aforementioned undesirable initial
rich spike during engine acceleration is effectively prevented.
Further, according to a more restricted method aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by, for an internal combustion engine with a combustion
chamber system and comprising an air-fuel mixture intake system
comprising an intake manifold, said internal combustion engine further
comprising a fuel injection valve fitted to said intake manifold
which is selectively opened and closed by selective supply of an
actuating signal thereto and which when so opened injects liquid
fuel into said intake manifold, said internal combustion engine
and said fuel injection valve operating according to an operational
cycle: an engine control method, comprising the processes, repeatedly
and alternatingly and/or simultaneously performed, of: (a) sensing
the current values of certain operational parameters of said internal
combustion engine, including sensing the value of the rate of flow
of intake air into said intake manifold by the use of an intake
air flow meter; (b) performing the following processes in the specified
order: (b1) based upon the current values of said sensed operational
parameters of said internal combustion engine, including the current
value of rate of flow of intake air into said intake manifold, calculating
the value of a first quantity representing the desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points; (b2) updating the value of a second
quantity representing the time smoothed desired amount of fuel to
be provided to said combustion chamber system of said internal combustion
engine during the time period between the next two fuel injection
pulse time points, by adding to said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points
the value produced by subtracting said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points
from said first quantity representing the desired amount of fuel
to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points and multiplying the result by a constant
value less than unity; and (b3) optionally further modifying said
second quantity representing the time smoothed desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points according to engine operational parameters;
and (c) at time points in said operational cycle of said internal
combustion engine and said fuel injection valve which are proper
fuel injection time points, if according to the current operational
conditions of said internal combustion engine it is currently proper
to inject fuel through said fuel injection valve, performing the
following processes in the specified order: (c1) modifying said
actuating signal according to the value of a third quantity representing
the actual corrected fuel amount to be injected through said fuel
injection valve in the next fuel injection pulse, said third quantity
representing the actual corrected fuel amount to be injected through
said fuel injection valve in the next fuel injection pulse being
calculated from the current value of said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points;
and (c2) supplying said modified actuating signal to said fuel injection
valve in such a fashion as to cause said fuel injection valve to
open for a time period which will allow an amount of fuel approximately
equal to the fuel amount represented by said third quality representing
the actual corrected fuel amount to be injected through said fuel
injection valve in the next fuel injection pulse to pass through
said fuel injection valve so as to be injected into said intake
manifold.
According to such a method, by time smoothing tthe value of said
first quantity representing the desired amount of fuel to be provided
to said combustion chamber system of said internal combustion engine
during the time period between the next two fuel injection pulse
time points in the way outlined to produce said second quantity
representing the time smoothed desired amount of fuel to be provided
to said combustion chamber system of said internal combustion engine
during the time period between the next two fuel injection pulse
time points, whose value thus pursues the value of said first quantity
representing the desired amount of fuel to be provided to said combustion
chamber system of said internal combustion engine during the time
period between the next two fuel injection pulse time points, both
during the operational conditions when fuel injection is being performed
into said air-fuel mixture intake system, and also during the operational
conditions when fuel injection into said air-fuel mixture intake
system is being cut off, thereby fluctuations in the output signal
of said intake air flow meter, due to overshooting thereof during
acceleration, can be taken account of. Thus, the amount of fuel
actually injected into said air-fuel mixture intake system through
said fuel injection valve is adjusted, so as to ensure that approximately
the correct amount of fuel actually reaches the combustion chamber
system of the internal combustion engine, both during the operational
conditions when fuel injection is being performed into said air-fuel
mixture intake system, and also during the operational conditions
when fuel injection into said air-fuel mixture intake system is
being cut off. Thus, occurrence of the aforementioned undesirable
initial rich spike during engine acceleration is again effectively
prevented.
Further, according to a more particular method aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by an engine control method of either one of the kinds
described above, wherein said constant value is less than about
0.1 and more particularly wherein said constant value is about
0.025.
According to such a method, the characteristic time period, over
which this time smoothing of said first quantity representing the
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points is performed,
is more than about ten times the time period taken to perform the
actions detailed in step (b); and more particularly may be about
forty times this time period.
Further, according to a more restricted method aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by, for an internal combustion engine with a combustion
chamber system and comprising an air-fuel mixture intake system
formed with walls and comprising an intake manifold, said internal
combustion engine further comprising a fuel injection valve fitted
to said intake manifold which is selectively opened and closed by
selective supply of an actuating signal thereto and which when so
opened injects liquid fuel into said intake manifold, said internal
combustion engine and said fuel injection valve operating according
to an operational cycle: an engine control method, comprising the
processes, repeatedly and alternatingly and/or simultaneously performed,
of: (a) sensing the current values of certain operational parameters
of said internal combustion engine, including sensing the value
of the rate of flow of intake air into said intake manifold by the
use of an intake air flow meter; (b) performing the following processes
in the specified order: (b1) based upon the current values of said
sensed operational parameters of said internal combustion engine,
including the current value of the rate of flow of intake air into
said intake manifold, calculating the value of a first quantity
representing the desired amount of fuel to be provided to said combustion
chamber system of said internal combustion engine during the time
period between the next two fuel injection pulse time points; (b2)
updating the value of a second quantity representing the time smoothed
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points, by adding
to said second quantity representing the time smoothed desired amount
of fuel to be provided to said combustion chamber system of said
internal combustion engine during the time period between the next
two fuel injection pulse time points the value produced by subtracting
said second quantity representing the time smoothed desired amount
of fuel to be provided to said combustion chamber system of said
internal combustion engine during the time period between the next
two fuel injection pulse time points from said first quantity representing
the desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points and multiplying
the result by a constant value less than unity; and (b3) optionally
further modifying said second quantity representing the time smoothed
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points according
to engine operational parameters; (c) calculating the value of a
third quantity representing the proportion of fuel in one pulse
of fuel injected through said fuel injection valve which will adhere
to said walls of said air-fuel mixture intake system, and the value
of a fourth quantity representing the proportion of the total amount
of fuel adhering to said walls of said air-fuel mixture intake system
which is sucked off therefrom to pass into said combustion chamber
system of said internal combustion engine during the time interval
between two successive fuel injection pulses; and (d) at time points
in said operational cycle of said internal combustion engine and
said fuel injection valve which are proper fuel injection time points,
performing the following processes in the specified order: (d1)
calculating, from the current value of a fifth quantity representing
the total amount of fuel adhering to said walls of said air-fuel
mixture intake system, and the current value of said fourth quantity
representing the proportion of the total amount of fuel adhering
to said walls of said air-fuel mixture intake system which is sucked
off therefrom to pass into said combustion chamber system of said
internal combustion engine during the time interval between two
successive fuel injection pulses, the value of a sixth quantity
representing the amount of fuel from the total amount of fuel adhering
to said walls of said air-fuel mixture intake system which will
be sucked off therefrom to pass into said combustion chamber system
of said internal combustion engine in the time interval between
the next fuel injection pulse time instant and the next fuel injection
pulse time instant after it; (d2) calculating, from the current
value of said second quantity representing the time smoothed desired
amount of fuel to be provided to said combustion chamber system
of said internal combustion engine during the time period between
the next two fuel injection pulse time points, from the current
value of said third quantity representing the proportion of fuel
in one pulse of fuel injected through said fuel injection valve
which will adhere to said walls of said air-fuel mixture intake
system, and from the current value of said sixth quantity representing
the amount of fuel from the total amount of fuel adhering to said
walls of said air-fuel mixture intake system which will be sucked
off therefrom to pass into said combustion chamber system of said
internal combustion engine in the time interval between the next
fuel injection pulse time instant and the next fuel injection pulse
time instant after it, the value of a seventh quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse; (d3) calculating, from the
current value of said seventh quantity representing the actual fuel
amount to be injected through said fuel injection valve in the next
fuel injection pulse and the current value of said third quantity
representing the proportion of fuel in one pulse of fuel injected
through said fuel injection valve which will adhere to said walls
of said air-fuel mixture intake system, the value of an eighth quantity
representing the amount of fuel from the next fuel injection pulse
that will adhere to said walls of said air-fuel mixture intake system;
(d4) updating the value of said fifth quantity representing the
total amount of fuel adhering to said walls of said air-fuel mixture
intake system by adding thereto the value of said eighth quantity
representing the amount of fuel from the next fuel injection pulse
that will adhere to said walls of said air-fuel mixture intake system
and by subtracting from the result of this addition the value of
said sixth quantity representing the amount of fuel from the total
amount of fuel adhering to said walls of said air-fuel mixture intake
system which will be sucked off therefrom to pass into said combustion
chamber system of said internal combustion engine in the time interval
between the next fuel injection pulse time instant and the next
fuel injection pulse time instant after it; (d5) modifying said
actuating signal according to the value of said seventh quantity
representing the actual fuel amount to be injected through said
fuel injection valve in the next fuel injection pulse; and (d6)
supplying said modified actuating signal to said fuel injection
valve in such a fashion as to cause said fuel injection valve to
open for a time period which will allow an amount of fuel approximately
equal to the fuel amount represented by said seventh quantity representing
the acutal fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse to pass through said fuel
injection valve so as to be injected into said intake manifold;
wherein the method used in subprocess (d2) for calculating the value
of said seventh quantity representing the actual fuel amount to
be injected through said fuel injection valve in the next fuel injection
pulse is such that the sum of the value of said seventh quantity
representing the actual fuel amount to be injected through said
fuel injection valve in the next fuel injection pulse and the value
of said sixth quantity representing the amount of fuel from the
total amount of fuel adhering to said walls of said air-fuel mixture
intake system which will be sucked off therefrom to pass into said
combustion chamber system of said internal combustion engine in
the time interval between the next fuel injection pulse time instant
and the next fuel injection pulse time instant after it less the
value of said eighth quantity representing the amount of fuel from
the next fuel injection pulse that will adhere to said walls of
said air-fuel mixture intake system is approximately equal to the
value of said second quantity representing the time smoothed desired
amount of fuel to be provided to said combustion chamber system
of said internal combustion engine during the time period between
the next two fuel injection pulse time points.
According to such a method, account is also kept of the total amount
of fuel adhering to the wall surfaces of the air-fuel mixture intake
system, by also performing the calculations detailed above; and
according thereto the amount of fuel actually injected into said
air-fuel mixture intake system through said fuel injection valve
is adjusted, so as to ensure that approximately the correct amount
of fuel actually reaches the combustion chamber system of the internal
combustion engine. Thus, occurrence of the aforementioned undesirable
later following lean spike during engine acceleration is also effectively
prevented.
Further, according to a more restricted method aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by, for an internal combustion engine with a combustion
chamber system and comprising an air-fuel mixture intake system
formed with walls and comprising an intake manifold, said internal
combustion engine further comprising a fuel injection valve fitted
to said intake manifold which is selectively opened and closed by
selective supply of an actuating signal thereto and which when so
opened injects liquid fuel into said intake manifold, said internal
combustion engine and said fuel injection valve operating according
to an operational cycle: an engine control method, comprising the
processes, repeatedly and alternatingly and/or simultaneously performed,
of: (a) sensing the current values of certain operational parameters
of said internal combustion engine, including sensing the value
of the rate of flow of intake air into said intake manifold by the
use of an intake air flow meter; (b) performing the following processes
in the specified order: (b1) based upon the current values of said
sensed operational parameters of said internal combustion engine,
including the current value of the rate of flow of intake air into
said intake manifold, calculating the value of a first quantity
representing the desired amount of fuel to be provided to said combustion
chamber system of said internal combustion engine during the time
period between the next two fuel injection pulse time points; (b2)
updating the value of a second quantity representing the time smoothed
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points, by adding
to said second quantity representing the time smoothed desired amount
of fuel to be provided to said combustion chamber system of said
internal combustion engine during the time period between the next
two fuel injection pulse time points the value produced by subtracting
said second quantity representing the time smoothed desired amount
of fuel to be provided to said combustion chamber system of said
internal combustion engine during the time period between the next
two fuel injection pulse time points from said first quantity representing
the desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points and multiplying
the result by a constant value less than unity; and (b3) optionally
further modifying said second quantity representing the time smoothed
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points according
to engine operational parameters; (c) calculating the value of a
third quantity representing the proportion of fuel in one pulse
of fuel injected through said fuel injection valve which will adhere
to said walls of said air-fuel mixture intake system, and the value
of a fourth quantity representing the proportion of the total amount
of fuel adhering to said walls of said air-fuel mixture intake system
which is sucked off therefrom to pass into said combustion chamber
system of said internal combustion engine during the time interval
between two successive fuel injection pulses; and (d) at time points
in said operational cycle of said internal combustion engine and
said fuel injection valve which are proper fuel injection time points,
performing the following processes in the specified order; (d1)
calculating, from the current value of a fifth quantity representing
the total amount of fuel adhering to said walls of said air-fuel
mixture intake system, and the current value of said fourth quantity
representing the proportion of the total amount of fuel adhering
to said walls of said air-fuel mixture intake system which is sucked
off therefrom to pass into said combustion chamber system of said
internal combustion engine during the time interval between two
successive fuel injection pulses, the value of a sixth quantity
representing the amount of fuel from the total amount of fuel adhering
to said walls of said air-fuel mixture intake system which will
be sucked off therefrom to pass into said combustion chamber system
of said internal combustion engine in the time interval between
the next fuel injection pulse time instant and the next fuel injection
pulse time instant after it; and then, if according to the current
operational conditions of said internal combustion engine it is
proper to inject fuel through said fuel injection valve, (d2) performing
the following processes in the specified order: (d2.1) calculating,
from the current value of said second quantity representing the
time smoothed desired amount of fuel to be provided to said combustion
chamber system of said internal combustion engine during the time
period between the next two fuel injection pulse time points, from
the current value of said third quantity representing the proportion
of fuel in one pulse of fuel injected through said fuel injection
valve which will adhere to said walls of said air-fuel mixture intake
system, and from the current value of said sixth quantity representing
the amount of fuel from the total amount of fuel adhering to said
walls of said air-fuel mixture intake system which will be sucked
off therefrom to pass into said combustion chamber system to said
internal combustion engine in the time interval between the next
fuel injection pulse time instant and the next fuel injection pulse
time instant after it, the value of a seventh quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse; (d2.2) calculating, from
the current value of said seventh quantity representing the actual
fuel amount to be injected through said fuel injection valve in
next fuel injection pulse and the current value of said third quantity
representing the proportion of fuel in one pulse of fuel injected
through said fuel injection valve which will adhere to said walls
of said air-fuel mixture intake system, the value of an eighth quantity
representing the amount of fuel from the next fuel injection pulse
that will adhere to said walls of said air-fuel mixture intake system;
(d2.3) updating the value of said fifth quantity representing the
total amount of fuel adhering to said walls of said air-fuel mixture
intake system by adding thereto the value of said eighth quantity
representing the amount of fuel from the next fuel injection pulse
that will adhere to said walls of said air-fuel mixture intake system
and by subtracting from the result of this addition the value of
said sixth quantity representing the amount of fuel from the total
amount of fuel adhering to said walls of said air-fuel mixture intake
system which will be sucked off therefrom to pass into said combustion
chamber system of said internal combustion engine in the time interval
between the next fuel injection pulse time instant and the next
fuel injection pulse time instant after it; (d2.4) modifying said
actuating signal according to the value of said seventh quantity
representing the actual feed amount to be injected through said
fuel injection valve in the next fuel injection pulse; and (d2.5)
supplying said modified actuating signal to said fuel injection
valve in such a fashion as to cause said fuel injection valve to
open for a time period which will allow an amount of fuel approximately
equal to the fuel amount represented by said seventh quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse to pass through said fuel
injection valve so as to be injected into said intake manifold;
but otherwise, if according to the current operational conditions
of said internal combustion engine it is not proper to inject fuel
through said fuel injection valve, then (d3) performing the following
process: (d3.1) updating the value of said fifth quantity representing
the total amount of fuel adhering to said walls of said air-fuel
mixture intake system by subtracting therefrom the value of said
sixth quantity representing the amount of fuel from the total amount
of fuel adhering to said walls of said air-fuel mixture intake system
which will be sucked off therefrom to pass into said combustion
chamber system of said internal combustion engine in the time interval
between the next fuel injection pulse time instant and the next
fuel injection pulse time instant after it; wherein the method used
in subprocess (d2.1) for calculating the value of said seventh quantity
representing the actual fuel amount to be injected through said
fuel injection valve in the next fuel injection pulse is such that
the sum of the value of said seventh quantity representing the actual
fuel amount to be injected through said fuel injection valve in
the next fuel injection pulse and the value of said sixth quantity
representing the amount of fuel from the total amount of fuel adhering
to said walls of said air-fuel mixture intake system which will
be sucked off therefrom to pass into said combustion chamber system
of said internal combustion engine in the time interval between
the next fuel injection pulse and the next fuel injection pulse
after it less the value of said eighth quantity representing the
amount of fuel from the next fuel injection pulse that will adhere
to said walls of said air-fuel mixture intake system is approximately
equal to the value of said second quantity representing the time
smoothed desired amount of fuel to be provided to said combustion
chamber system of said internal combustion engine during the time
period between the next two fuel injection pulse time points.
According to such a method, account is also kept of the total amount
of fuel adhering to the wall surfaces of the air-fuel mixture intake
system, by also performing the calculations detailed above, both
during the operational conditions when fuel injection is being performed
into said air-fuel mixture intake system, and also during the operational
conditions when fuel injection into said air-fuel mixture intake
system is being cut off; and according thereto the amount of fuel
actually injected into said air-fuel mixture intake system through
said fuel injection valve is adjusted, so as to ensure that approximately
the correct amount of fuel actually reaches the combustion chamber
system of the internal combustion engine, both during the operational
conditions when fuel injection is being performed into said air-fuel
mixture intake system, and also during the operational conditions
when fuel injection into said air-fuel mixture intake system is
being cut off. Thus, occurrence of the aforementioned later following
undesirable lean spike during engine acceleration is also effectively
prevented, and good fuel economy of the internal combustion engine
is available.
Further, according to a more particular method aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by an engine control method of any single one of the
last two kinds described above, wherein the method used for calculating
the value of said sixth quantity representing the amount of fuel
from the total amount of fuel adhering to said walls of said air-fuel
mixture intake system which will be sucked off therefrom to pass
into said combustion chamber system of said internal combustion
engine in the time interval between the next fuel injection pulse
time instant and the next fuel injection pulse time instant after
it is to multiply the value of said fifth quantity representing
the total amount of fuel adhering to said walls of said air-fuel
mixture intake system by the value of said fourth quantity representing
the proportion of the total amount of fuel adhering to said walls
of said air-fuel mixture intake system which is sucked off therefrom
to pass into said combustion chamber system of said internal combustion
engine during the time interval between two successive fuel injection
pulses.
According to such a method, said sixth quantity representing the
amount of fuel from the total amount of fuel adhering to said walls
of said air-fuel mixture intake system which will be sucked off
therefrom is calculated simply and yet effectively. It has been
shown, by the aforementioned process of experiment, that this method
of calculation is adequate for predicting the value of the sucked
off amount of fuel.
Further, according to another more particular method aspect of
the present invention, these and other objects are more particularly
and concretely accomplished by an engine control method of any single
one of the last three kinds described above, wherein the method
used for calculating the value of said seventh quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse is to subtract from the value
of said second quantity representing the time smoothed desired amount
of fuel to be provided to said combustion chamber system of said
internal combustion engine during the time period between the next
two fuel injection pulse time points the value of said sixth quantity
representing the amount of fuel from the total amount of fuel adhering
to said walls of said air-fuel mixture intake system which will
be sucked off therefrom to pass into said combustion chamber system
of said internal combustion engine in the time interval between
the next fuel injection pulse and the next fuel injection pulse
after it, and to divide the result by unity less the value of said
third quantity representing the proportion of fuel in one pulse
of fuel injected through said fuel injection valve which will adhere
to said walls of said air-fuel mixture intake system.
According to such a method, said seventh quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse is calculated simply and
yet effectively, by a formula which will be explained in detail
in the portion of this specification entitled "DESCRIPTION
OF THE PREFERRED EMBODIMENT". It has been shown, by the aforementioned
process of experiment, that this method of calculation is adequate
for predicting the value of the sucked off amount of fuel.
Further, according to yet another more particular method aspect
of the present invention, these and other objects are more particularly
and concretely accomplished by an engine control method of any single
one of the last four kinds described above, wherein the method used
for calculating the value of said eighth quantity representing the
amount of fuel from the next fuel injection pulse that will adhere
to said walls of said air-fuel mixture intake system is to multiply
the value of said seventh quantity representing the actual fuel
amount to be injected through said fuel injection valve in the next
fuel injection pulse by the value of said third quantity representing
the proportion of fuel in one pulse of fuel injection through said
fuel injection valve which will adhere to said walls of said air-fuel
mixture intake system.
According to such a method, said eighth quantity representing the
amount of fuel from the next fuel injection pulse that will adhere
to said walls of said air-fuel mixture intake system is calculated
simply and yet effectively. It has been shown, by the aforementioned
process of experiment, that this method of calculation is adequate
for predicting the value of the sucked off amount of fuel.
Further, according to the most general device aspect of the present
invention, these and other objects are accomplished by, for an internal
combustion engine with a combustion chamber system and comprising
an air-fuel mixture intake system comprising an intake manifold,
said internal combustion engine further comprising a fuel injection
valve fitted to said intake manifold which is selectively opened
and closed by selective supply of an actuating signal thereto and
which when so opened injects liquid fuel into said intake manifold,
said internal combustion engine and said fuel injection valve operating
according to an operational cycle: an engine control device, comprising:
(a) a plurality of sensors which sense the current values of certain
operational parameters of said internal combustion engine, including
an intake air flow meter which senses the current value of rate
of flow of intake air into said intake manifold; (b) an interface
device, which, whenever it receives a fuel injection valve control
electrical signal, dispatches said fuel injection valve actuating
signal to said fuel injection valve; and (c) an electronic computer,
which receives supply of signals from said sensors indicative of
said current values of said certain operational parameters of said
internal combustion engine, including a signal from said intake
air flow meter indicative of the current value of rate of flow of
intake air into said intake manifold; (d) said electronic computer
repeatedly and alternatingly and/or simultaneously: (d1) performing
the following process in the specified order: (d1.1) based upon
the current values of said sensed operational parameters of said
internal combustion engine, including the current value of rate
of flow of intake air into said intake manifold, calculating the
value of a first quantity representing the desired amount of fuel
to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points; (d1.2) updating the value of a second
quantity representing the time smoothed desired amount of fuel to
be provided to said combustion chamber system of said internal combustion
engine during the time period between the next two fuel injection
pulse time points, by adding to said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points
the value produced by subtracting said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points
from said first quantity representing the desired amount of fuel
to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points and multiplying the result by a constant
value less than unity; and (d1.3) optionally further modifying said
second quantity representing the time smoothed desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points according to engine operational parameters;
and (d2) at time points in said operational cycle of said internal
combustion engine and said fuel injection valve which are proper
fuel injection time points, performing the following processes in
the specified order: (d2.1) calculating, from the current value
of said second quantity representing the time smoothed desired amount
of fuel to be provided to said combustion chamber system of said
internal combustion engine during the time period between the next
two fuel injection pulse time points, the value of a third quantity
representing the actual fuel amount to be injected through said
fuel injection valve in the next fuel injection pulse; and (d2.2)
outputting to said interface device a fuel injection valve control
electrical signal, based upon the value of said third quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse, such as to cause said fuel
injection valve to open for a time period which will allow an amount
of fuel approximately equal to the fuel amount represented by said
third quantity representing the actual fuel amount to be injected
through said fuel injection valve in the next fuel injection pulse
to pass through said fuel injection valve so as to be injected into
said intake manifold.
According to such a structure, by said electronic computer thus
time smoothing the value of said first quantity representing the
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points in the way
outlined to produce said second quantity representing the time smoothed
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points, whose value
thus pursues the value of said first quantity representing the desired
amount of fuel to be provided to said combustion chamber system
of said internal combustion engine during the time period between
the next two fuel injection pulse time points, thereby fluctuations
in the output signal of said intake air flow meter, due to overshooting
thereof during acceleration, can be taken account of; and thereby
occurrence of the aforementioned undesirable initial rich spike
during engine acceleration is effectively prevented.
Further, according to a more restricted device aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by, for an internal combustion engine with a combustion
chamber system and comprising an air-fuel mixture intake system
comprising an intake manifold, said internal combustion engine further
comprising a fuel injection valve fitted to said intake manifold
which is selectively opened and closed by selective supply of an
actuating signal thereto and which when so opened injects liquid
fuel into said intake manifold, said internal combustion engine
and said fuel injection valve operating according to an operational
cycle: an engine control device, comprising: (a) a plurality of
sensors which sense the current values of certain operational parameters
of said internal combustion engine, including an intake air flow
meter which senses the current value of rate of flow of intake air
into said intake manifold; (b) an interface device, which, whenever
it receives a fuel injection valve control electrical signal, dispatches
said fuel injection valve actuating signal to said fuel injection
valve; and (c) an electonic computer, which receives supply of signals
from said sensors indicative of said current values of said certain
operational parameters of said internal combustion engine, including
a signal from said intake air meter indicative of the current value
of rate of flow of intake air into said intake manifold; (d) said
electronic computer repeatedly and alternatingly and/or simultaneously:
(d1) performing the following processes in the specified order:
(d1.1) based upon the current values of said sensed operational
parameters of said internal combustion engine, including the current
value of rate of flow of intake air into said intake manifold, calculating
the value of a first quantity representing the desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points; (d1.2) updating the value of a second
quantity representing the time smoothed desired amount of fuel to
be provided to said combustion chamber system of said internal combustion
engine during the time period between the next two fuel injection
pulse time points, by adding to said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injecting pulse time points
the value produced by subtracting said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points
from said first quantity representing the desired amount of fuel
to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points and multiplying the result by a constant
value less than unity; and (d1.3) optionally further modifying said
second quantity representing the time smoothed desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points according to engine operational parameters;
and (d2) at time points in said operational cycle of said internal
combustion engine and said fuel injection valve which are proper
fuel injection time points, if according to the current operational
conditions of said internal combustion engine it is proper to inject
fuel through said fuel injection valve, performing the following
processes in the specified order: (d2.1) calculating, from the current
value of said second quantity representing the time smoothed desired
amount of fuel to be provided to said combustion chamber system
of said internal combustion engine during the time period between
the next two fuel injection pulse time points, the value of a third
quantity representing the actual fuel amount to be injected through
said fuel injection valve in the next fuel injection pulse; and
(d2.2) outputting to said interface device a fuel injection valve
control electrical signal, based upon the value of said third quantity
representing the actual fuel amount to be injected through said
fuel injection valve in the next fuel injection pulse, such as to
cause said fuel injection valve to open for a time period which
will allow an amount of fuel approximately equal to the fuel amount
represented by said third quantity representing the acutal fuel
amount to be injected through said fuel injection valve in the next
fuel injection pulse to pass through said fuel injection valve so
as to be injected into said intake manifold.
According to such a structure, by said electronic computer thus
time smoothing the value of said first quantity representing the
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points in the way
outlined to produce said second quantity representing the time smoothed
desired amount of fuel to be provided to said combustion chamber
system of said internal combustion engine during the time period
between the next two fuel injection pulse time points, whose value
thus pursues the value of said first quantity representing the desired
amount of fuel to be provided to said combustion chamber system
of said internal combustion engine during the time period between
the next two fuel injection pulse time points, both during the operational
conditions when fuel injection is being performed into said air-fuel
mixture intake system, and also during the operational conditions
when fuel injection into said air-fuel mixture intake system is
being cut off, thereby fluctuations in the output signal of said
intake air flow meter, due to overshooting thereof during acceleration,
can be taken account of. Thus, the amount of fuel actually injected
into said air-fuel mixture intake system through said fuel injection
valve is adjusted, so as to ensure that approximately the correct
amount of fuel actually reaches the combustion chamber system of
the internal combustion engine, both during the operational conditions
when fuel injection is being performed into said air-fuel mixture
intake system, and also during the operational conditions when fuel
injection into said air-fuel mixture intake system is being cut
off. Thus, occurrence of the aforementioned undesirable initial
rich spike during engine acceleration is again effectively prevented,
and good engine fuel economy is promoted.
Further, according to a more particular device aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by an engine control device of either one of the kinds
described above, wherein said constant value is less than about
0.1 and in particular wherein said constant value is about 0.025.
According to such a structure, the characteristic time period,
over which this time smoothing is performed by said electronic computer,
is more than about ten times the time period taken by said electronic
control computer to perform the actions detailed in step (d) above;
and more particularly may be about forty times this time period.
Further, according to a more resticted device aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by, for an internal combustion engine with a combustion
chamber system and comprising an air-fuel mixture intake system
formed with walls and comprising an intake manifold, said internal
combustion engine further comprising a fuel injection valve fitted
to said intake manifold which is selectively opened and closed by
selective supply of an actuating signal thereto and which when so
opened injects liquid fuel into said intake manifold, said internal
combustion engine and said fuel injection valve operating according
to an operational cycle: an engine control device, comprising: (a)
a plurality of sensors which sense the current values of certain
operational parameters of said internal combustion engine, including
an intake air flow meter which senses the current value of rate
of flow of intake air into said intake mainfold; (b) an interface
device, which, whenever it receives a fuel injection valve control
electrical signal, dispatches said fuel injection valve actuating
signal to said fuel injection valve; and (c) an electronic computer,
which receives supply of signals from said sensors indicative of
said current values of said certain operational parameters of said
internal combustion engine, including a signal from said intake
air flow meter indicative of the current value of rate of flow of
the intake air into said intake manifold; (d) said electronic computer
repeatedly and alternatingly and/or simultaneously: (d1) performing
the following processes in the specified order: (d1.1) based upon
the current values of said sensed operational parameters of said
internal combustion engine, including the current value of rate
of flow of intake air into said intake manifold, calculating the
value of a first quantity representing the desired amount of fuel
to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points; (d1.2) updating the value of a second
quantity representing the time smoothed desired amount of fuel to
be provided to said combustion chamber system of said internal combustion
engine during the time period between the next two fuel injection
pulse time points, by adding to said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points
the value produced by subtracting said second quantity representing
the time smoothed desired amount of fuel to be provided to said
combustion chamber system of said internal combustion engine during
the time period between the next two fuel injection pulse time points
from said first quantity representing the desired amount of fuel
to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points and multiplying the result by a constant
value less than unity; and (d1.3) optionally further modifying said
second quantity representing the time smoothed desired amount of
fuel to be provided to said combustion chamber system of said internal
combustion engine during the time period between the next two fuel
injection pulse time points according to engine operational parameters;
(d2) calculating the value of a third quantity representing the
proportion of fuel in one pulse of fuel injected through said fuel
injection valve which will adhere to said walls of said air-fuel
mixture intake system, and the value of a fourth quantity representing
the proportion of the total amount of fuel adhering to said walls
of said air-fuel mixture intake system which is sucked off therefrom
to pass into said combustion chamber system of said internal combustion
engine during the time interval between two successive fuel injection
pulses; and (d3) at time points in said operational cycle of said
internal combustion engine and said fuel injections valve which
are proper fuel injection time points, performing the following
processes in the specified order: (d3.1) calculating, from the current
value of a fifth quantity representing the total amount of fuel
adhering to said walls of said air-fuel mixture intake system, and
the current value of said fourth quantity representing the proportion
of the total amount of fuel adhering to said walls of said air-fuel
mixture intake system which is sucked off therefrom to pass into
said combustion chamber system of said internal combustion engine
during the time interval between two successive fuel injection pulses,
the value of a sixth quantity representing the amount of fuel from
the total amount of fuel adhering to said walls of said air-fuel
mixture intake system which will be sucked off therefrom to pass
into said combustion chamber system of said internal combustion
engine in the time interval between the next fuel injection pulse
time instant and the next fuel injection pulse time instant after
it; (d3.2) calculating, from the current value of said second quantity
representing the time smoothed desired amount of fuel to be provided
to said combustion chamber system of said internal combustion engine
during the time period between the next two fuel injection pulse
time points, from the current value of said third quantity representing
the proportion of fuel in one pulse of fuel injected through said
fuel injection valve which will adhere to said walls of said air-fuel
mixture intake system, and from the current value of said sixth
quantity representing the amount of fuel from the total amount of
fuel adhering to said walls of said air-fuel mixture intake system
which will be sucked off therefrom to pass into said combustion
chamber system of said internal combustion engine in the time interval
between the next fuel injection pulse time instant and the next
fuel injection pulse time instant after it, the value of a seventh
quantity representing the actual fuel amount to be injected through
said fuel injection valve in the next fuel injection pulse; (d3.3)
calculating, from the current value of said seventh quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse and the current value of
said third quantity representing the proportion of fuel in one pulse
of fuel injected through said fuel injection valve which will adhere
to said walls of said air-fuel mixture intake system, the value
of an eighth quantity representing the amount of fuel from the next
fuel injection pulse that will adhere to said walls of said air-fuel
mixture intake system; (d3.4) updating the value of said fifth quantity
representing the total amount of fuel adhering to said walls of
said air-fuel mixture intake system by adding thereto the value
of said eighth quantity representing the amount of fuel from the
next fuel injection pulse that will adhere to said walls of said
air-fuel mixture intake system and by subtracting from the result
of this addition the value of said sixth quantity representing the
amount of fuel from the total amount of fuel adhering to said walls
of said air-fuel mixture intake system which will be sucked off
therefrom to pass into said combustion chamber system of said internal
combustion engine in the time interval between the next fuel injection
pulse time instant and the next fuel injection pulse time instant
after it; and (d3.5) outputting to said interface device a fuel
injection valve control electrical signal, based upon the value
of said seventh quantity representing the actual fuel amount to
be injected through said fuel injection valve in the next fuel injection
pulse, such as to cause said fuel injection valve to open for a
time period which will allow an amount of fuel approximately equal
to the fuel amount represented by said seventh quantity representing
the acutal fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse to pass through said fuel
injection valve so as to be injected into said intake manifold;
wherein the method used by said electronic computer in subprocess
(d3.2) for calculating the value of said seventh quantity representing
the actual fuel amount to be injected through said fuel injection
valve in the next fuel injection pulse is such that the sum of the
value of said seventh quantity representing the actual fuel amount
to be injected through said fuel injection valve in the next fuel
injection pulse and the value of said sixth quantity representing
the amount of fuel from the total amount of fuel adhering to said
walls of said air-fuel mixture intake system which will be sucked
off therefrom to pass into said combustion chamber system of said
internal combustion engine in the time interval between the next
fuel injection pulse time instant and the next fuel injection pulse
time instant after it less the value of said eighth quantity representing
the amount of fuel from the next fuel injection pulse that will
adhere to said walls of said air-fuel mixture intake system is approximately
equal to the value of said second quantity representing the time
smoothed desired amount of fuel to be provided to said combustion
chamber system of said internal combustion engine during the time
period between the next two fuel injection pulse time points.
According to such a structure, said electronic computer also keeps
account of the total amount of fuel adhering to the wall surfaces
of the air-fuel mixture intake system, by performing the calculations
detailed above; and according thereto the amount of fuel actually
injected into said air-fuel mixture intake system through said fuel
injection valve is adjusted by said electronic computer, so as to
ensure that approximately the correct amount of fuel actually reaches
the combustion chamber system of the internal combustion engine.
Thus, occurrence of the aforementioned later following undesirable
lean spike during engine acceleration is also effectively prevented.
Further, according to a more restricted device aspect of the present
invention, these and other objects are more particularly and concretely
accomplished by, for an internal combustion engine with a combustion
chamber system and comprising an air-fuel mixture intake system
formed with walls and comprising an intake manifold, said internal
combustion engine further comprising a fuel injection valve fitted
to said intake manifold which is selectively opened and closed by
selective supply of an actuating signal thereto and which when so
opened injects liquid fuel into said intake manifold, said internal
combustion engine and said fuel injection valve operating according
to an operational cycle: an engine control device, comprising: (a)
a plurality of sensors which sense the current values of certain
operational parameters of said internal combustion engine, including
an intake air flow meter which senses the current value of rate
of flow of intake air into said intake manifold; (b) an interfa |