Abstrict An improved fuel flow meter construction for visually indicating
the flow rate of fuel therethrough. A vertically extending tubular
body has a central vertically extending bore with a sight glass
mounted on its upper end, and has an indicating needle vertically
movable within the body and sight glass. A hollow sleeve is mounted
within the bore of the tubular body and has a metering orifice formed
at its bottom end. A vapor deflector is mounted on the upper open
end of the sleeve. An intermediate portion of the sleeve is spaced
from the bore wall and forms an outer downstream fuel passage therebetween
which communicates with a fuel outlet line connected to the tubular
body. The interior of the sleeve provides an inner upstream fuel
passage above the orifice and communicates with a fuel inlet line
connected to the tubular body below the metering orifice. Fuel outlet
ports are formed in the top portion of the sleeve connecting the
inner fuel passage with the outer fuel passage. The metering needle
has a tapered metering portion which extends freely movably through
the orifice, and the top portion of the metering needle extends
through a closely controlled complementary hole formed in the vapor
deflector. The metering needle raises and lowers within the sight
glass depending upon the rate of fuel flow through the metering
orifice providing a visual indication of the fuel flow rate. The
vapor deflector reduces the accumulation of fuel vapors in the sight
glass, and the inner and outer fuel passages reduce turbulence adjacent
the metering orifice, thereby improving the accuracy of the metering
of the fuel flow rate.
Claims I claim:
1. Improved fuel flow meter construction of the type having a vertically
extending tubular body with a vertically extending opening formed
therethrough, fuel inlet and outlet means provided on the body,
a closed sight glass mounted on the upper end of the tubular body,
metering orifice means provided within the vertically extending
opening, a metering needle movably mounted within the vertically
extending opening and extending through the metering orifice means
and having an upper end extending into the sight glass, and the
sight glass having position indicating means; the improvement including:
a. hollow sleeve means telescopically mounted within the vertically
extending opening and forming upwardly extending inner fuel passage
means within the sleeve means, said upwardly extending fuel passage
means communicating with the fuel inlet means;
b. relief means provided on the exterior of the sleeve means and
forming downwardly extending outer fuel passage means about the
exterior of the sleeve means within a portion of the tubular body
opening means, said downwardly extending fuel passage means communicating
with the fuel outlet means;
c. vapor ejector means mounted within the vertically extending
opening of the tubular body, and having an inwardly tapered lower
end projecting into an open top end of the sleeve means;
d. a vertically extending accurately controlled central opening
formed through the vapor ejector means complementary to the upper
portion of the metering needle, said needle being freely vertically
movable through said central opening;
e. outlet port means formed adjacent the upper portion of the sleeve
means and extending between the inner and outer fuel passage means;
and
f. the upper end of the metering needle providing visual indication
in the sight glass during fuel flow through the fuel inlet means,
upwardly through the orifice means around the metering needle, upwardly
through the sleeve means inner fuel passage means, through the outlet
port means and downwardly through the outer fuel passage means,
and through the fuel outlet means of the tubular body indicating
the rate of fuel flow through said orifice means.
2. The improved meter construction defined in claim 1 in which
the sleeve means has top and bottom collar means with outer diameters
complementary to the diameter of the vertically extending tubular
body opening, and an integral main tubular portion extending between
said collar means; and in which the tubular portion of the sleeve
means is spaced from the tubular body providing the relief means
within the tubular body opening which forms the outer fuel passage
means.
3. The improved meter construction defined in claim 2 in which
the outlet port means includes a plurality of holes formed in the
tubular portion of the sleeve means, adjacent to the top collar
means.
4. The improved meter construction defined in claim 2 in which
the orifice means has a circular knife-like edge; and in which the
orifice means is formed within the bottom collar means of the sleeve
means.
5. The improved meter construction defined in claim 1 in which
the vapor ejector means is telescopically mounted on the open top
end of the sleeve means; in which the outlet port means includes
a plurality of holes formed in the sleeve means adjacent the top
end of the sleeve means; and in which the tapered end of the vapor
ejector means extends into the sleeve means and projects below the
outlet port means holes.
6. The improved meter construction defined in claim 5 in which
the vapor ejector means has a cylindrical body portion with an integral
top collar; in which the vapor ejector means tapered end has a conical
configuration and extends downwardly from the cylindrical body portion;
and in which the top collar is supported on the open top end of
the sleeve means with the cylindrical body portion being in telescopical
contact with the interior of the top collar means of the sleeve
means.
7. The improved meter construction defined in claim 6 in which
resilient washer means is mounted circumferentially on the collar
means of the vapor ejector means and provides a seal at a junction
between the vapor ejector means, tubular body and sight glass.
8. The improved meter construction defined in claim 1 in which
the fuel outlet means communicates with the outer downward fuel
passage means, adjacent the lower end of said outer passage means.
9. The improved meter construction defined in claim 1 in which
resilient washer means is mounted on the upper end of the metering
needle and is engageable with the vapor ejector means to provide
a sealing effect between the central opening of the ejector means
and the metering needle, when said needle is in a lowermost position.
10. The improved meter construction defined in claim 1 in which
weight means is mounted on the upper end of the metering needle
to increase the effective weight of said needle for metering fuel
flow of fuels having various densities.
11. The improved meter construction defined in claim 10 in which
the weight means is an annular member telescopically mounted on
the metering needle; in which a resilient washer is mounted on the
upper end of the needle and retains the annular weight thereon;
and in which the washer is engageable with the vapor ejector means
providing a seal for the central opening of the ejector means and
the metering needle, when said needle is in a lowermost position.
12. The improved meter construction defined in claim 1 in which
the upper end of the metering needle is formed with a position indicating
head; and in which the indicating head is spaced sufficiently from
the sight glass to compensate for irregularities in said sight glass.
13. The improved meter construction defined in claim 1 in which
the central opening of the vapor ejector means is accurately controlled
with respect to the upper portion of the metering needle, with said
needle being freely slidable with respect to said vapor ejector
yet restricting passage of fuel vapor into the sight glass through
said central opening around said metering needle.
14. The improved meter construction defined in claim 13 in which
the controlled relationship between the central opening of the vapor
ejector means and metering needle provides a damping action on said
needle.
15. The improved meter construction defined in claim 1 in which
the metering orifice means is formed in the bottom end of the sleeve
means.
16. The improved meter construction defined in claim 15 in which
the metering orifice means provides a restricted opening between
the lower portion of the tubular body vertically extending opening
and the inner fuel passage means of the sleeve means.
Description BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The invention relates to improvement in fuel flow meters of the
type having a vertically upwardly extending sight glass for directly
visually indicating the flow rate of fuel therethrough. More particularly,
the invention relates to a fuel flow meter of the foregoing type
having means reducing the accumulation of vapors in the sight glass
and reducing turbulence adjacent the metering orifice to obtain
more accurate flow rate indications.
2. DESCRIPTION OF THE PRIOR ART
Various prior constructions of fuel flow meters of the type having
an upwardly extending sight glass portion through which fuel flow
rates may be visually observed or indicated have included a vertically
slidable rod, the upper end of which is received in the sight glass
portion to provide the visual indications and the lower end of which
is provided with a disc or float-like member such as shown in U.S.
Pat. Nos. 1215129 1989366 2073372 2076562 2293987
2388672 2955465 and 2350343. The disc or float member is
freely vertically slidable in a particularly shaped metering chamber
and may extend through an upper or lower orifice or restriction
in the vertical flow meter. Various problems and undesirable operating
characteristics have been encountered with such meter constructions,
which are set forth in and which are largely eliminated by my fuel
flow meter construction of U.S. Pat. No. 3117446.
Several minor problems and difficulties have been encountered with
the fuel flow meter construction of the type shown in my patent,
as well as being present in other meter constructions set forth
in the patents listed above. Fuel vapors will collect in the sight
glass, especially during stop and go driving in warm weather, which
seriously affects the damping action between the pin head and sight
glass in thos constructions where the pin head is used to achieve
a damping action. These fuel vapors or bubbles in the sight glass
affect the accuracy of the metering being provided. Another problem
encounterred with such prior meter constructions is the exact manufacturing
tolerances required in the sight glass tube or chamber and needle
head where the metering needle head is used as the damping means
in combination with the sight glass. Such precisioned manufactured
and machined parts increase considerably the cost of the fuel flow
meter since most of the commercially available low-cost glass or
plastic tubing used for the sight glass is not provided with the
required internal bore linearity and uniformity.
Still another minor problem encountered with meter constructions
of the type shown in my U.S. Pat. No. 3117446 is the creation
of turbulence in the area of the metering orifice. The fuel or liquid
being measured flows upwardly through the restricted orifice at
a relatively high rate of speed, which flow then must reverse and
flow downwardly through the outlet holes located just above the
metering orifice inside the tubular body which creates turbulence
with the incoming upwardly flowing fuel. A further shortcoming of
such prior meter constructions is the formation of the metering
orifice at a central position in the interior bore of a tubular
member requiring machining from both the upper and lower ends of
the tube to form the orifice, which tube also must be provided with
external threaded areas for attaching and mounting additional components
thereon. Again, this precision machining at a relatively difficult
location on the tubular member to form the orifice increases the
cost per unit of prior meter constructions. Still another shortcoming
of such prior meter constructions is the inability to use such constructions
to measure the fuel flow rate of fluids other than the particular
fluid (gasoline) for which it was designed, since the density of
the fluid being measured affects the reading due to the buoyancy
exerted on the specifically weighted and designed metering needle,
disc or float member mounted thereon.
SUMMARY OF THE INVENTION
Objectives of the invention include providing an improved fuel
flow meter construction which overcomes the difficulties discussed
above, while still providing a visual indicating flow meter construction
of maximum simplicity, at a minimum of cost, and which is adaptable
to extremely small flow rates and different densities of fuel; providing
such an improved fuel flow meter construction which uses a freely,
vertically, movable metering needle in combination with a simple
metering orifice formed in an outlet tube which is telescopically
mounted within a bore of an outer tubular member, which eliminates
expensive machining costs heretofore required for forming the metering
orifice of prior constructions, and which sleeve forms an inner
fuel passage which communicates with the fuel inlet line providing
an upstream path for the fuel flow after passing through the metering
orifice, and which provides an outer fuel passage for the downstream
fuel flow which communicates with the fuel outlet line, thereby
eliminating turbulence heretofore encountered in the vicinity of
the metering orifice; providing such an improved meter construction
having a vapor deflector telescopically mounted on the top open
end of the improved orifice sleeve, which vapor deflector has an
inwardly tapered conical lower end surrounding a closely controlled
opening extending through the deflector which is complementary to
the diameter of the metering needle, thereby reducing the passage
of fuel vapor into the sight glass, and in which the controlled
vapor ejector opening provides a metering needle damping action
without the heretofore required critical machining of the needle
head diameter with respect to the internal diameter of the sight
glass as in prior constructions; providing such an improved meter
construction in which annular weights may be mounted on the upper
end of the metering needle beneath the needle head to enable the
meter construction to be used for measuring fuel flow rates of fuels
having various densities; providing such a meter construction in
which a sealing O-ring may be mounted on the upper end of the metering
needle head to provide an effective seal between the metering needle
and vapor deflector opening reducing the flow of vapors and therethrough
into the sight glass when the engine is stopped and no fuel is flowing;
providing such a meter construction which increases the accuracy
of the flow rate indication due to the reduction in the collection
of fuel vapors in the sight glass and reduction of turbulence in
the vicinity of the metering orifice; and providing such an improved
fuel flow meter construction which eliminates difficulties heretofore
encountered, achieves the stated objectives simply and effectively,
and solves problems and satisfies existing needs.
These objectives and advantages are obtained by the improved fuel
flow meter construction of the type having a vertically extending
tubular body with a vertically extending opening formed therethrough,
fuel inlet and outlet means provided on the body with a closed sight
glass mounted on the upper end of the tubular body, a metering needle
movably within the vertically extending opening having an upper
end extending into the sight glass, and in which the sight glass
has position indicating means; the general nature of the improvements
may be stated as including hollow sleeve means telescopically mounted
within the vertically extending opening and forming upwardly extending
inner fuel passage means within the sleeve means, the upwardly extending
fuel passage means communicating with the fuel inlet means; relief
means provided on the exterior of the sleeve means and forming downwardy
extending outer fuel passage means about the exterior of the sleeve
means within a portion of the tubular body opening means, with the
downwardly extending fuel passage means communicating with the fuel
outlet means; metering orifice means having a circular knife-edge
being formed in the bottom end of the sleeve means; vapor ejector
means mounted within the vertically extending opening of the tubular
body, and having an inwardly tapered lower end projecting into an
open top end of the sleeve means; a vertically extending accurately
controlled central opening formed through the vapor ejector means
complementary to the upper portion of the metering needle, the needle
being freely vertically movable through the central opening; outlet
port means formed adjacent the upper portion of the sleeve means
and extending between the inner and outer fuel passage means; and
the upper end of the metering needle providing visual indication
in the sight glass during fuel flow through the fuel inlet means,
upwardly through the orifice means around the metering needle, upwardly
through the sleeve means inner fuel passage means, through the outlet
port means and downwardly through the outer fuel passage means,
and through the fuel outlet means of the tubular body, indicating
the rate of fuel flow through said orifice means.
BRIEF DESCRIPTION OF THE DRAWING
A preferred embodiment of the invention - illustrative of the best
mode in which applicant has contemplated applying the principle
- is set forth in the following description and shown in the accompanying
drawing, and is particularly and distinctly pointed out and set
forth in the appended claims.
FIG. 1 is a front elevation of the improved fuel flow meter construction,
with the metering needle shown in an intermediate position;
FIG. 2 is an enlarged fragmentary sectional view of the metering
portion of the improved flow meter construction, with only a portion
of the sight glass being shown mounted thereon;
FIG. 3 is a perspective view of the vapor ejector of the improved
fuel flow meter construction of FIGS. 1 and 2;
FIG. 4 is a perspective view of the orifice sleeve of the improved
fuel flow meter construction of FIGS. 1 and 2;
FIG. 5 is a sectional view taken on line 5--5 FIG. 2;
FIG. 6 is a sectional view taken on line 6--6 FIG. 2;
FIG. 7 is a sectional view taken on line 7--7 FIG. 2; and
FIG. 8 is a sectional view taken on line 8--8 FIG. 2.
Similar numerals refer to similar parts throughout the drawing.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The improved fuel flow meter construction of the present invention
is illustrated particularly in FIGS. 1 and 2 and is indicated generally
at 1. Construction 1 includes a main tubular, vertically extending
body, indicated generally at 2 having a central opening 3 extending
substantially the entire vertical height of body 2. body 2 includes
a central metering portion indicated generally at 4 and has an
upper sight glass assembly indicated generally at 5 mounted on
the top of body 2.
Metering portion 4 is formed with a fuel inlet line 6 which is
threadably received in a junction tee 7 mounted on the lower end
of body 2. Tee 7 may include a threaded nipple 8 providing an additional
fuel inlet port for tubular body 2. A fuel outlet line 9 is threadably
connected to a collar 10 which is telescopically surrounding body
2 intermediate the vertical height thereof, and which forms a fuel
chamber 11 which communicates with outlet line 9. Fuel chamber 11
communicates with central body openings 3 through a plurality of
fuel outlet openings 12 formed through body 2 (FIG. 2).
Fuel outlet line 9 and collar 10 are maintained properly positioned
on body 2 and properly positioned relative to fuel outlet openings
12 by a lower collar 13 which is threadably, telescopically received
on threaded portion 14 of body 2. A washer 15 is interposed between
collars 10 and 13 and bears upwardly against a resilient sealing
O-ring 16 which is located within an annular recess 17 formed in
the bottom end of collar 10.
The upper end of collar 10 (FIG. 2) abuts a second mounting washer
18 which bears downwardly against a second resilient sealing O-ring
19 mounted in an upper annular recess 20 formed in the top of collar
10. Washer 18 abuts a resilient sealing washer 21 underlying a representative
mounting member 22 which may be, for instance, the cowling covering
an automobile engine. Overlying mounting member 22 is another resilient
sealing washer 23 which is maintained in pressed sealing engagement
with mounting member 22 by a collar 24.
Sight glass assembly 5 is mounted on body 2 immediately above an
annular shoulder 25 which is formed on the upper end of tubular
body 2 which shoulder is engaged by a complementary internal shoulder
26 of collar 24. Sight glass 5 includes a sight glass cover 27 formed
with a closed upper end 28 and having a sighting window 29. window
29 preferably extends substantially the entire vertical length of
cover 27 and terminates downwardly from closed upper end 28 and
upwardly from the lower end of cover 27. The lowermost end of cover
27 is formed with a reduced threaded end portion 30 which is telescopically
slidable over the uppermost end of tubular body 2 and secured thereon
by threadable engagement with collar 24 (FIG. 2).
A transparent sight glass tube 31 is received within cover 27 and
extends between closed upper end 28 and the top portion of tubular
body 2. The open bottom end of sight glass 31 is engaged with a
sealing O-ring 33 (FIG. 2) with a similar O-ring (not shown) providing
sealing engagement between the upper open end of sight glass tube
31 and sight glass cover 27. Flow graduations 34 are formed on sight
glass cover 27 adjacent the sighting window 29 as shown in FIG.
1. An air release opening preferably is formed through closed upper
end 28 of sight glass cover 27 and is closed by a screw 35.
A metering needle, indicated generally at 36 is mounted freely
vertically, movable in opening 3 of tubular body 2 and includes
a metering stem portion 37 and an indicating head portion 38. Indicating
head portion 38 is mounted at the upper end of the metering stem
portion 37 and is positioned within and surrounded by tubular sight
glass 31. Metering head 38 has a flat top surface 32 which serves
as an indicating line as sighted through sighting window 29 and
can compare against indicating graduations 34.
The upper portion 39 of metering stem 37 preferably has a circular
cross-sectional configuration as shown in FIG. 6 with the lower
stem portion 40 being inwardly tapered downwardly as shown in FIGS.
7 and 8. The tapered metering stem portion 40 decreases progressively
in cross-section at a predetermined rate downwardly to the lower
end of needle 36. The rate of taper is determined by certain considerations
discussed in detail in the above mentioned U.S. Pat. No. 3117446
which in turn determines the proper locations of graduations 34.
In accordance with the invention, an orifice sleeve indicated generally
at 45 (FIG. 4), is snugly mounted within central openings 3 of tubular
body 2 (FIG. 2). Sleeve 45 has an elongated tubular configuration
with a central bore 50 and with enlarged upper and lower collar
ends 46 and 47 respectively, formed integrally with tubular-shaped
body portion 48. A plurality of fuel outlet ports 49 are formed
in the upper end of tubular body 48 beneath and adjacent to upper
collar 46. Sleeve 45 is mounted within central opening 3 of tubular
body 2 and is supported on an internal annular shoulder 51 formed
on tubular body 2 below fuel outlet openings 12. In further accordance
with the invention, a metering orifice 52 is formed by an inwardly
tapering circular edge 53 formed in lower collar end 47 (FIG. 2),
instead of being formed as an integral part of tubular body 2 which
prior constructions required expensive machining operations and
manufacturing procedures.
Central bore 50 of sleeve 45 provides an inner "upstream"
fuel passage which axially aligns and communicates with central
opening 3 of the lower portion of tubular body 2 which in turn
communicates with fuel inlet 6. The relief or spacing provided between
tubular portion 48 of sleeve 45 and the internal surface forming
tubular opening 3 provides an outer "downstream" fuel
passage 54 within tubular body 2 (FIG. 2). Outer fuel passage 54
communicates with the inner fuel passage or central bore 50 by way
of fuel outlet ports 49 and communicates with fuel outlet line
9 through fuel outlet openings 12. Thus, fuel entering fuel inlet
line 6 flows upwardly through opening 3 of the lower portion of
tubular body 2 through metering orifice 52 and around metering
stem portion 40 then upwardly through inner fuel passage 50 through
fuel outlet ports 49 downwardly through outer fuel passage 54
and then into fuel outlet line 9 through outlet openings 12.
Another important feature of the invention, is vapor ejector 55
(FIGS. 2 and 3) which is telescopically received within the upper
open end of orifice sleeve 45. Vapor ejector 55 preferably, has
a tubular body 56 terminating in a tapered conical lowere end 57
and an enlarged top collar portion 58 formed integrally with body
56. An axial bore or central opening 59 extends throughout vapor
ejector 55 and has an accurately controlled circular cross-sectional
configuration or diameter complementary to upper portion 39 of metering
needle 36.
Sealing O-ring 33 is mounted on the circumference of collar portion
58 and is in pressure sealing engagement between the bottom edge
of sight glass 31 and the top edge of tubular body 2. O-ring 33
prevents escape of vapors from between the exterior of ejector 55
and the interior of sleeve 45 and form between the exterior of
sleeve collar 46 and tubular body 2.
Indicating head 38 of metering needle 36 has a diameter less than
the internal diameter of tubular sight glass 31 so as to provide
a sufficiently large annular space 61 (FIG. 2) at all times between
the circumference of head 38 and the walls of sight glass 31 to
insure complete free vertical movement of head 38 within the sight
glass. This spacing provides satisfactory operation of the metering
needle without regard to any imperfections of the internal bore
of the sight glass, and eliminates complex and expensive machining
and sizing of indicating head portion 38 as in prior flow meter
constructions. A sealing O-ring 62 is mounted on the upper end of
metering needle 36 beneath indicating head 38 providing a sealing
effect to bore 59 of vapor ejector 55 when there is no fuel flow
through meter construction 1 and needle 36 is in an unraised position
and rests upon the top of vapor ejector 55. An annular weight ring
63 may be mounted on the upper end of metering needle 36 by O-ring
62 the purpose of which is discussed below.
At the commencement of operation of flow meter construction 1
fuel flows into the lower portion of body opening 3 through fuel
inlet line 6 upwardly through the circular metering orifice 52
between this orifice and taper 41 of metering stem portion 37 and
upwardly through the inner fuel passage formed by sleeve bore 50
and outwardly through fuel outlet ports 49 and then downwardly
through outer fuel passage 54 and into fuel outlet 9 through outlet
openings 12. The flowing fuel raises needle 36 within tubular body
2 and correspondingly, indicating head 38 within sight glass 31.
As the flow of fuel increases and decreases, the metering needle
36 will automatically move upwardly and downwardly proportionate
to such flow and to provide greater or less opening through metering
orifice 52 between circular edges 53 of the orifice and tapering
metering stem portion 37.
As set forth in U.S. Pat. No. 3117446 the fact that metering
needle 36 is tapered and is working against a stationary circular
metering orifice 52 the pressure drop across the restriction is
not constant. As the metering needle 36 rises, the weight being
supported is constant but the area supporting it reduces so that
the pressure drop across the restriction increases and flow rates
are, therefore, not directly proportional to the area of the opening.
Thus, it is necessary to take into account in calibration of the
metering construction varying pressure as well as a varying orifice
opening area. As stated, in this patent, the calculations necessary
for calibration may be readily accomplished by known mathematical
formulas apparent to those skilled in the art. Furthermore, although
such calibration is somewhat more involved than the straight line
calibration of prior constructions, the disadvantages of being required
to make such calculations are clearly outweighed by the advantages
of the present invention. Likewise, in view of the fact that a tapered
vertically movable metering needle acts against a knife-edge orifice,
changes in viscosity of fuel have only a negligible effect, even
at the minimum flow rates, so that accurate fuel flow readings may
be made at such lower fuel flow rates. Furthermore, friction between
the vertically moving metering needle and the other stationary parts
of the metering construction are negligible.
The particular arrangement of conical tapered end 57 of vapor ejector
55 together with outlet ports 49 reduce and nearly eliminate the
accumulation of vapor bubbles and foam within sight glass 31. Tapered
end 57 terminates in a sharp knife-like edge 60 which deflects nearly
all of the rising fuel bubbles and fuel vapor upwardly along the
outside surface of tapered end 57 where they flow outwardly through
ports 49 and downwardly in outer fuel passage 54 to fuel outlet
line 9. Thus, nearly all such vapor bubbles are prevented from entering
sight glass 31 through the closely controlled space between vapor
ejector bore 59 and metering needle portion 39. Heretofore, it had,
under certain conditions, been necessary to operate air vent screw
35 at the top of sight glass cover 27 frequently to permit escape
of the accumulated vapors from the top portion of sight glass 31.
The controlled spacing between needle portion 39 and vapor ejector
bore 59 also provides a damping effect to needle 36 heretofore achieved
by the matching of indicating head 38 and the internal walls of
sight glass 31. If desirable, the spacing between needle portion
39 and vapor ejector 55 may be increased with the damping effect
being provided by an enlarged needle head 38 as in my prior fuel
meter construction, with tapered end 57 of the vapor ejector still
deflecting the majority of the vapor and air bubbles around and
upwardly through ports 49.
Improved fuel flow meter construction 1 has the advantage of reducing
the machining for forming metering orifice 52 within the lower end
of orifice sleeve 45 eliminates turbulence and the resulting vapor
bubbles produced thereby in the vicinity of the metering orifice
by eliminating the upward and downward movement of fuel within the
same fuel passage by providing inner and outer fuel passages 50
and 54 within vertically extending opening 3 of tubular body 2.
Vapor ejector 55 also reduces the accumulation of vapor and bubbles
within sight glass 31 which affects accurate fuel flow readings
and requires repeated manipulation of vent screw 35 to remove the
same.
Another important feature of the improved fuel flow meter construction
is the mounting of annular weight ring 63 on the upper end of metering
needle 36. As discussed above in my U.S. Pat. No. 3117446 the
weight of metering needle 36 is important in calibration of the
fuel flow meter, as well as the particular fuel to be measured,
which in most instances, will be gasoline for vehicles. It is desirable,
however, to be able to adapt the fuel flow meter to other fuel systems
and to other types of fuels, for example, kerosine, diesel fuel,
etc. By using mathematical equations and formulas and the specific
densities of the fuels to be measured, a specific amount of weight
can be readily calculated which is required to be added to needle
36 for measuring the fuel flow rate of higher density fuels. Weights
63 preferably are annular metallic rings which are telescopically
mounted on needle portion 39 and maintained thereon by O-ring 62.
O-ring 62 provides the further advantage to the improved meter
construction in that it provides an effective seal or check valve
for vapor deflector bore 59 when no fluid is flowing. O-ring 62
is in abutting engagement with the top surface of vapor ejector
collar 58 when no fuel is flowing through the meter and will prevent
passage of fuel vapor or bubbles from escaping upwardly through
vapor ejector bore 59 into sight glass 31.
Accordingly, the improved fuel flow meter construction is simplified,
provides an effective, safe, inexpensive, and efficient device which
achieves all the enumerated objectives, provides for eliminating
difficulties encountered with prior devices, and solves problems
and obtains new results in the art.
In the foregoing description, certain terms have been used for
brevity, clearness and understanding; but no unnecessary limitations
are to be implied therefrom beyond the requirements of the prior
art, because such terms are used for descriptive purposes and are
intended to be broadly construed.
Moreover, the description and illustration of the invention is
by way of example, and the scope of the invention is not limited
to the exact details shown or described.
Having now described the features, discoveries and principles of
the invention, the manner in which the improved fuel flow meter
construction is constructed and used, the characteristics of the
construction, and the advantageous, new and useful results obtained;
the new and useful structures, devices, elements, arrangements,
parts and combinations, are set forth in the appended claims. |