Abstrict A closed crankcase ventilation system for a recirculating effluent
gas stream of an internal combustion engine is provided with an
air flow meter. The flow meter provides a signal to an engine controller
continuously during normal engine operation that is proportional
to the flow of gas through the system. The signal is used to trigger
a control system output that may activate an alarm, shutdown the
engine, or indicate a need for engine service.
Claims What is claimed is:
1. An internal combustion engine, comprising: at least one combustion
chamber and a reciprocating piston, the combustion chamber having
an exhaust and an air intake on a first side of the piston and a
crankcase on a second side of the piston; a closed crankcase ventilation
system for recirculating an effluent gas stream from the crankcase
to the air intake, the closed crankcase ventilation system further
comprising at least one flow meter disposed in the effluent gas
stream that measures the volume of gas flowing through at least
a part of the ventilation system continuously whenever the engine
is operated and produces a signal indicative of the volume of gas
flow; and a control system that receives the signal indicative of
the volume of gas flow and monitors the signal to provide at least
one control system output that is dependent upon the sensed quantity
of gas flow, wherein the control system output is recorded in an
engine operation log that records the volume of gas flow as an engine
diagnostic parameter.
2. The internal combustion engine of claim 1 wherein the flow meter
is an electronic air flow meter.
3. The internal combustion engine of claim 2 wherein the flow meter
is a simple turbine type of flow meter.
4. The internal combustion engine of claim 1 wherein the flow meter
is a mass flow sensor that also detects an increase in oil concentration
in the effluent gas stream.
5. The internal combustion engine of claim 1 further comprising
a breather ported to the crankcase.
6. The internal combustion engine of claim 5 wherein the breather
further comprises a plurality of rocker cover breathers.
7. The internal combustion engine of claim 1 wherein the control
system determines if the volume of gas flow exceeds a predetermined
level and that produces the control system output when the gas flow
exceeds the predetermined level.
8. The internal combustion engine of claim 7 wherein the control
system output causes the engine to shut down or to operate at reduced
power.
9. The internal combustion engine of claim 7 wherein the control
system output activates an alarm perceptible to an operator to warn
of an engine problem or an impending engine problem.
10. The internal combustion engine of claim 1 wherein the engine
diagnostic parameter is used to determine whether a crankcase pressure
switch should be replaced.
11. The internal combustion engine of claim 1 wherein the engine
diagnostic parameter is used to determine whether the engine should
be overhauled.
12. A closed crankcase ventilation system for an internal combustion
engine having a crankcase, an air inlet, an air intake system, and
an engine control, comprising: a set of hoses ported to the crankcase
of the engine and connecting to the air intake system that directs
an effluent gas stream from the crankcase to the air intake system;
a flow meter connected in fluid flow communication with the hoses
to continuously measure the air flow volume or mass passing through
at least a part of the hoses during normal engine operation, wherein
the flow meter produces a signal indicative of the air flow volume
or mass that is provided to the engine control and the engine control
monitors the signal and determines if an engine service output should
be provided, wherein the flow meter is used in conjunction with
a crankcase pressure transducer to detect an increase in oil concentration
in the effluent gas stream.
13. The closed crankcase ventilation system of claim 12 further
comprising a breather through which the hoses are ported to the
crankcase.
14. The closed crankcase ventilation system of claim 13 wherein
the breather further comprises a plurality of rocker cover breathers.
15. The closed crankcase ventilation system of claim 12 wherein
the flow meter is an electronic air flow meter.
16. The closed crankcase ventilation system of claim 15 wherein
the flow meter is a simple turbine type of flow meter.
17. The closed crankcase ventilation system of claim 12 wherein
the flow meter is a mass flow sensor.
18. An internal combustion engine, comprising: at least one combustion
chamber and a reciprocating piston, the combustion chamber having
an exhaust and an air intake on a first side of the piston and a
crankcase on a second side of the piston; a closed crankcase ventilation
system for recirculating an effluent gas stream from the crankcase
to the air intake, the closed crankcase ventilation system further
comprising at least one flow meter disposed in the effluent gas
stream that measures the volume of gas flowing through at least
a part of the ventilation system continuously whenever the engine
is operated and produces a signal indicative of the volume of gas
flow; and a control system that receives the signal indicative of
the volume of gas flow and monitors the signal to provide at least
one control system output that is dependent upon the sensed quantity
of gas flow exceeding a predetermined level, the control system
output causing the engine to shut down or to operate at reduced
power.
19. An internal combustion engine, comprising: at least one combustion
chamber and a reciprocating piston, the combustion chamber having
an exhaust and an air intake on a first side of the piston and a
crankcase on a second side of the piston; a closed crankcase ventilation
system for recirculating an effluent gas stream from the crankcase
to the air intake, the closed crankcase ventilation system further
comprising at least one flow meter disposed in the effluent gas
stream that measures the volume of gas flowing through at least
a part of the ventilation system continuously whenever the engine
is operated and produces a signal indicative of the volume of gas
flow; and a control system that receives the signal indicative of
the volume of gas flow and monitors the signal to provide at least
one control system output that is dependent upon the sensed quantity
of gas flow exceeding a predetermined level, the control system
output activating an alarm perceptible to an operator to warn of
an engine problem or an impending engine problem.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to closed crankcase ventilation systems
for internal combustion engines.
2. Background Art
The crankcase of an operating internal combustion engine is pressurized
by blow-by gases (gases that flow past the piston rings, valve stems
and turbo seals), and in the case of a two-cycle engine, by leakage
from the air box. Venting is required to control crankcase pressure
and thereby minimize oil leakage past crankshaft seals, oil pan
gaskets, etc., and to prevent harmful liquids, including sulfuric
acid, from condensing in the engine. The large quantity of lube
oil contained in the crankcase, which may be extremely agitated
under normal engine operating conditions, complicates the ventilation
task. High temperature and agitation cause oil mist (vapor and droplets)
to become entrained in the crankcase gases or effluent. This oil
mist must be separated from the effluent prior to its discharge
from the crankcase, to prevent loss of useful engine oil and environmental
pollution. An effective crankcase ventilation system is one that
controls crankcase pressure, and minimizes loss and contamination
of the lube oil.
There are two types of crankcase ventilation systems commonly used
in internal combustion engines. An "open" crankcase ventilation
system discharges crankcase effluent gases to the atmosphere, while
a "closed" crankcase ventilation system avoids atmospheric
discharge by piping the gases to the engine's air inlet system,
(typically upstream of the turbocharger compressor in a diesel engine).
The function of an open system is to vent effluent gases to the
atmosphere, free from oil droplets. It must maintain minimal positive
crankcase pressure throughout the normal wear life of the engine,
while operating under all speeds, loads and operating attitudes
for which the engine was designed. A closed system has the additional
function of limiting vacuum in the crankcase through use of a valve
or by allowing filtered fresh air into the engine. Diesel engines
typically use a Crankcase Depression Regulator (diaphragm valve).
Gasoline engines, which have lower blow-by flow rates than diesels,
typically use PCV's (Positive Crankcase Ventilation Valves).
The closed crankcase ventilation system has the added requirement
of minimizing the inherent risk of carrying excessive oil (pull-over)
into the air intake system. Any oil delivery to the air intake is
considered undesirable oil consumption and increased exhaust emissions.
Extreme oil pull-over can cause loss of engine control or over-speed
if the oil is burned, or flooding of cylinders and hydrostatic lock,
with associated damage (e.g., bent connecting rod or blown cylinder
head gasket). Crankcase ventilation system design must ensure that
the system (either open or closed) will function properly for the
life of the engine, under all possible operating conditions, including
operation at extreme tilt angles, increasing blow-by levels due
to engine wear, air inlet restrictions, engine speeds, etc.
The quantity of effluent gas flowing through a crankcase ventilation
system naturally increases over time as pistons, piston rings, cylinder
lines, and other engine components wear. Failure of a cylinder component
(e.g., scuffing, broken or burned ring, piston, etc.) can cause
a drastic increase in effluent volume. Furthermore, a failure of
a single cylinder may, if the engine is continued to operate, cause
catastrophic engine failure due to secondary damage (e.g., connecting
rod through the wall of the crankcase), or in the case of an engine
with a closed crankcase ventilation system due to oil pull-over.
With an open crankcase ventilation system, this flow increase results
in increased crankcase pressure. Crankcase pressure monitors have
been used successfully on engines with open crankcase ventilation
systems to detect a cylinder failure, allowing the engine to be
shutdown before major secondary damage occurs. On engines with a
closed crankcase ventilation system, the system itself limits pressure
increase thereby making crankcase pressure monitors ineffective.
Another limitation of crankcase pressure monitors is that they are
set for a single pressure, which if exceeded triggers a response;
no information about the engine is given at various operating pressures
below the preset limit.
Blow-by measurement is a commonly used diagnostic technique during
engine development or for evaluating the condition of an engine
in service. The usual method employed is to attach a gas flow meter
to the engine ventilation system. High readings can indicate a worn
out engine, loss of ring sealing, impending cylinder kit failure,
or sealing problems in other engine systems (e.g., turbocharger).
Ever more stringent emission requirements have led to more effective
oil separation in closed crankcase ventilation systems. Some systems
already incorporate filters that need to be periodically replaced
for proper operation. Engine oil consumed through recirculated effluent
may someday have to be controlled through the life of an engine
to ensure compliance with emission standards.
There is a need for a simple and cost effective system for continuous
monitoring of engine blow-by gas flow, for use as a tool to evaluate
the condition of an engine, and to diagnose problems associated
with increased blow-by. There is a need to warn the engine operator
of crankcase ventilation system malfunction or need to change filters
(for fresh air or oil separation) in a closed crankcase ventilation
system during normal engine operation. There is a need for detecting
cylinder kit damage, particularly in closed crankcase ventilation
systems, and of warning the operator or reducing engine power to
avoid subsequent catastrophic engine failure. There may be a need
in the future to monitor the amount of oil consumed through a closed
crankcase ventilation system, or a need to detect an increased level
of oil concentration in the effluent gas stream. The present invention
is directed to providing such a system that addresses the above
problems as summarized below.
SUMMARY OF THE INVENTION
According to one aspect of the invention, an internal combustion
engine is provided with a closed crankcase ventilation system including
a flow meter. The engine comprises at least one combustion chamber
and a reciprocating piston. The combustion chamber has an exhaust
port and an air intake on a first side of the piston and crankcase
on a second side of the piston. The closed crankcase ventilation
system recirculates a effluent gas stream from the crankcase to
the air intake. At least one flow meter is disposed in the effluent
gas stream to measure the volume of gas flowing through the ventilation
system. A signal is produced by the flow meter that senses the volume
of gas flow. The engine control system receives the signal indicative
of the volume of gas flow and monitors the signal to provide a control
system output based upon the sensed volume of gas flow. The control
system output can then be sent to an engine operation log that electronically
records the volume of gas flow as an engine diagnostic parameter.
This blow-by history can indicate the amount of wear through the
life of the engine. The control system output can be used to warn
the operator of a sudden increase in blow-by, indicating that the
engine is in need of service (e.g., to replace ventilation system
filters or to correct other engine component malfunctions). The
control system output can be used to reduce engine power or shut
the engine down to prevent subsequent major damage that could occur
following relatively minor damage to a cylinder, piston, piston
ring or other engine component.
According to another aspect of the present invention a closed crankcase
ventilation system is provided for an ignition engine having a crankcase,
an air inlet, and an engine control. The internal combustion engine
may be a compression ignition or spark ignition engine that may
be turbocharged or naturally aspirated. The ventilation system is
ported from the crankcase to the air intake system of the engine.
A set of hoses direct an effluent gas stream from the crankcase
to the air intake system. At least one flow meter is connected in
fluid flow communication with the hoses to measure the air flow
volume passing through the hoses. The measured effluent flow may
be routed to the upstream side of a turbocharger compressor of a
turbocharged engine or to the intake manifold of a naturally aspirated
engine. The flow meter produces a signal indicative of air flow
volume. The signal is provided to the engine control that monitors
the signal to determine if the engine should be shut down or serviced.
According to other aspects of the invention the crankcase may be
ported through a breather that may comprise one or more rocker cover
breathers. Alternatively, the breather may comprise a flywheel housing
breather, oil pan breather, cylinder block breather or gear case
breather.
The flow meter may be an electronic air flow meter. More specifically,
the flow meter may be a simple turbine type flow meter with a magnetic
pick-up. Alternatively, the flow meter may be a mass flow sensor
that is capable of detecting an increase in oil concentration in
the effluent gas stream. In another alternative embodiment, the
flow meter could be used in conjunction with a continuous pressure
output sensor (crankcase pressure transducer). The flow meter and
crankcase pressure transducer may offer a more cost effective system
that would be capable of detecting an increase in oil concentration
in the effluent gas stream.
These and other aspects of the present invention will be better
understood in view of the attached drawings and following detailed
description of a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of an internal combustion engine having
a closed crankcase ventilation system and a flow meter; and
FIG. 2 is a perspective view of a compression ignition internal
combustion engine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
Referring now to FIG. 1 an internal combustion engine 10 is shown
in schematic form to illustrate the flow of crankcase blow-by gases
in a closed crankcase ventilation system made according to the present
invention. The internal combustion engine 10 has at least one combustion
chamber 12. A piston 16 is received in each of the combustion chambers
12 for reciprocation as a result of the internal combustion process.
The combustion chamber 12 has an intake valve 18 through which air
is drawn as part of the combustion process.
The engine 10 has a crankcase 20 in which the crankshaft 22 is
disposed. The crankshaft 22 is connected to each of the pistons
16 by a connecting rod 24. During the combustion process, a portion
of the products of combustion may be drawn into the crankcase 20
around the piston 16 that are known as crankcase blow-by gases.
A closed crankcase ventilation system 26 routes a effluent gas
stream 28 to the engine air intake 30. A flow meter 32 is provided
in the closed crankcase ventilation system 26 to measure the volume
of gas flow constituted in the effluent gas stream 28.
Referring now to FIG. 2 an internal combustion engine 10 is shown
that includes a crankcase 20 that is ventilated by means of the
closed crankcase ventilation system 26. The closed crankcase ventilation
system 26 directs the effluent gas stream 28 to the engine air intake
30. The flow meter 32 provides an electronic engine input to the
engine control module 34 of the engine 10. The flow meter 32 is
connected by means of hoses 36 to a crankcase breather 38 that is
mounted on a rocker cover 40. The crankcase breather 38 that is
illustrated in FIG. 2 is a rocker cover breather, however, it should
be understood that other types of breathers may be used in accordance
with the present invention such as a flywheel housing breather,
an oil pan breather, a cylinder block breather, or a gear case breather.
The type of breather is determined by engine design considerations
and the specific types of breathers are equivalent in function and
in the way that they accomplish the same desired result.
In operation, engine blow-by gases are directed as a effluent gas
stream 28 from the crankcase 20 through the closed crankcase ventilation
system 26 to the engine air intake 30. The flow meter 32 is preferably
an electronic air flow meter. The electronic air flow meter may
be a simple turbine air flow meter or may be a mass flow sensor.
The use of a mass flow sensor would permit the system to detect
an increase in oil concentration in the effluent gas stream. The
flow meter may also be used in conjunction with a crankcase pressure
transducer to detect an increase in the effluent gas stream.
The control system, or ECM 34 receives electrical signals indicative
of the volume of gas flow from the flow meter. The control system
monitors the signal to provide at least one control system output
that is dependent upon the sensed quantity of gas flow.
The control system 34 determines if the volume of gas flow exceeds
a predetermined level. If so, the control system produces a control
system output. The control system output may be used by the engine
to shut down the engine or cause the engine to operate at a reduced
power level. Alternatively, the control system output can be used
to activate an alarm that may be used to warn an operator of an
engine problem or an impending engine problem. The control system
output may also be recorded in an engine operation log that electronically
records the volume of gas flowing through the crankcase ventilation
system as an engine diagnostic parameter.
The engine diagnostic parameter may be used to determine whether
an engine should be overhauled and may also be used in determining
whether a crankcase pressure switch should be replaced.
While embodiments of the invention have been illustrated and described,
it is not intended that these embodiments illustrate and describe
all possible forms of the invention. Rather, the words used in the
specification are words of description rather than limitation, and
it is understood that various changes may be made without departing
from the spirit and scope of the invention. |