US2506995A - Fuel supply system - Google Patents

Description

y 1950 M. E. CHANDLER 2,506,995

FUEL SUPPLY SYSTEM Filed Dec. 1, 1945 2 Shets-Sheet 1 'IIIIWIIHHII! FIG.|

INVENTOR. 5 M/LTU/V E. [HQ/VDLEIQ AGENT y 1950 M. E. CHANDLER 2,506,995

FUEL SUPPLY SYSTEM Filed Dec. 1, 1945 2 Sheets-Sheet 2 FIG. 2

INVENTOR. M/L TU/V [H fi/VDLE/ AGENT Patented May 9, 1950 UNIT FUEL SUPPLY SYSTEM Milton E. Chandler, New Britain, Conn, assignor;

by mesne assignments, to Niles-Rement-Rond Company, West Hartford, Conn, a corporation of New Jersey Application December 1, 194.5, SerialNo. 632,219

9 Qiaims.

This invention relates to fuel supply apparatus for internal combustion engines. It is particularly concerned with a fuel supply system wherein a pump is employed for transmitting fuel from a supply source to the engine.

An object of the invention is the provision of novel means of simple construction for controlling the supply of fuel in response to both the rate of fuel flow and the rate of airflow to the engine.

A further object is the provision of a novel and efficient relief valvefor the fuel supply pump, which relief valve is controlled both by the rate of fuel flow and the rate of air-flow to the engine.

A more specific feature of the invention comprises a valve element movable in response to the difference'between the air differential pressure and the fuel differential pressure for controlling the by-passingof fuel from .the outlet to the inlet side of the fuel pump and thereby controlling the rate of supply of fuel to the engme.

Other features of the invention will be hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a view in longitudinal vertical section illustrating a combined pump and fuel control valve embodying features of my invention.

Fig. 2 illustrates diagrammatically a fuel 3.

housing I2 which contains a pump it .of generally conventional design. The :pump comprises a rotor l5 having the usual blades or vanes ll, and driven by a shaft is which is splined at its outer end, as indicated at I53, so that it may readily be driven through a suitable connection from the engine. The inner end of shaft is drivingly connected to rotor: it by splines 2|. Fuel is received by the pump through an inlet connection 29 and isdischarged throughan outlet 22.

A by-passvalve arrangement. of known-con.- strnction is provided, comprising a valve-element 2a which fits into a bore 25 in the member 2%, the latter being threadedly fitted into a LXI (Cl. 1G341) passage of fuel downwardly through the bore 2'5. If, however, the pump inlet pressure for any reason exceeds the discharge pressure by a predetermined amount, the valve 2 opens, permitting fuel to by-pass the pump rotor ldand to flow from the inlet 2'8 past'the valve, through chamber 29, and thence directly to the outlet 22. Thisarrangement is useful when two pumps are connected in series in a fluid line. If one pump fails to operate for some reason, the byvalve on that pump-opens to allow the other pump to :move fuel past .it. Such by-pass arrangement is well-known, and nonovelty is claimed therefor in this application.

The end of the pump rotor It opposite the shaft is is drivingly connected to a piston 30, which is mounted for both rotary and translatory motion in a bearing sleeve 32, fitted within an extension of the housing I2. The driving connection between the rotor l5 and piston 33 may take any suitable-form for effecting rotation of said piston while-at the same time permitting translation thereof. Said connection may, as shown, comprise a pinionSA .ona shaft 35 -which is driven by the rotor 16 through splines .31. Pinion 34 meshes with an internal gear 36 on the piston 30, the teeth of said internalgear being of sufficient length to permit translation of the piston throughout its maximum range without disengagement of said gear 35 from said pinion .34. The piston may thus be continuously rotated with the pump rotor l8, while also being .movablelongitudinally in the sleeve 32.

Rotation of the pump. rotor It draws fuel from a suitable tank or reservoir through a con- :duit 38 (Fig. 2) and opening 253 (Fig. l) and impels said fuel through discharge opening 22 into a conduit ll! (Fig. 2). Fromsaid conduit the fuel may pass to a mixture control valve 42 (the portion 49' of said conduit All adjacent said mixture control valve being shown, for. convenience, on a smaller scalethan the portion of said conduit adjacent the housing [2). From the mixture control valve 42, the fuel may pass through a jet system 44, then through a conduit G8 to a pressure control valve 158,.and thence to a fuel discharge nozzle 59 in an air passage 52 which communicates with. the intake manifold of the engine.

The mixture control 42 includes a disk valve t3, which, when in the position shown in the drawing (termed the .lean position), permits fuel from the conduit 40 to flow only through conduit 54 :to-the jet system 44. However, said disk valve is movable from the position shown to one (termed the rich position) in which the fuel from conduit 58 may flow to the jet system through both the conduit 54 and conduit 56, as is well understood in the art.

Fuel entering the jet system 44 through the conduit 54 passes either through a fixed restriction 58 or through a restriction 65 controlled by an enrichment valve 52 biased to closed position by a spring. Fuel flowing to said jet system through conduit 56 passes through a fixed restriction 64. Fuel flowing through the restrictions 60 and 54 also flows through a restriction 66 before entering the conduit 45.

A conduit 68 is connected at one end to said conduit 45 and at its opposite end to a passage 'II] in the housing I2, which passage in turn communicates, through passage I2 in bearing sleeve 32, with a chamber I at the left of the piston 38. Thereby the pressure of the fuel emerging from the jet system is applied to the left hand end of said piston (as viewed in Fig. 1). At the same time, the pressure of the fuel on its way to the jet system is applied through chamber 29 to the right hand end of the piston 35 Thus said piston is subjected to the fuel pressure difl'erential across the jet system, which pressure differential is a measure of the fuel flowing to the engine per unit of time.

The pressure control valve 48 comprises a valve member I6 secured to a diaphragm I8 which is urged by a spring 80 in a direction to close the opening 82 through which fuel must flow to reach the nozzle 50. When the pressure of the fuel in the space below the diaphragm I8 is sufficient to overcome the action of the spring 80, the valve I6 is raised, and fluel flows through said opening 82 and thence to nozzle 50. Thus the fuel flowing through conduit 46 is maintained under substantially constant pressure by the spring-actuated diaphragm 8!]. Pressure control valves of the type illustrated at 43 are well known, and I claim no novelty therefor in this application.

Suitably secured to the forward or lefthand end of the housing I2 is a casing 84 containing a flexible diaphragm 86, which separates said casing into a pair of chambers 88 and 90. Port 92 in chamber 88 is connected by a conduit 94 (Fig. 2) to one or more impact tubes 96 in the path of air entering the passage 52; while port 98 in chamber 98 is connected to a Venturi restriction It!!! in said passage, through a conduit The diaphragm 8B is connected to piston 38 by any suitable means whereby movement of the diaphragm in either direction is imparted to said piston, without interfering with continuous 1'0- tation of the piston One such means which may be employed to advantage is illustrated in Fig. 1, wherein a recessed member I56 passes through the center of the diaphragm and is pinned or otherwise suitably secured thereto. Rotatably mounted near one end in a bearing I96 in said member IE4 is a shaft I538 which throughout the greater portion of its length extends through a bearing sleeve IIB. At the aforementioned end, said shaft I63 has a head I89 which abuts against a wall of a recess in the member I64, so that movement of the diaphragm 86 to. the right (Fig. l) is transmitted to said shaft. At its other end, said shaft I98 is provided with a recessed head H2 having one or more fingers engaging openings or slots in lugs on the piston 30, one of which lugs is shown at H4, so that said shaft rotates with said piston and also transmits longitudinal movement thereto in response to movement of the diaphragm 86. A ball IIB may, as shown, be mounted in a recess in said head I I2 to provide an anti-friction thrust bearing between said shaft I08 and the piston 30.

The conduit I02 is shown communicating with a chamber H8, which chamber communicates through conduit I25 with the throat of the Venturi I519. The conduit 94, which receives the total or dynamic pressure of the air at the Venturi entrance, communicates with the chamber IE8 through a passage containing a restriction I 22 and also controlled by a valve I24 positioned by a bellows I26 in said chamber I I8. The function of said valve I24 and bellows I25 is to reduce the total pressure differential produced by the Venturi I 99 by an amount sufficient to correct for decrease in density of the air clue to altitude or temperature, so that the pressure drop appearing across the restriction I22 is a measure of the mass of air flowing through the Venturi per unit of time. This arrangement is completely described in my Patent No. 2,393,144, issued January 15, 1946. Since the pressure drop across said restriction I22 is applied to the diaphragm 86, it will be apparent that said diaphragm is subjected to a force which is a measure of the rate of said mass air flow.

In the portion of the housing I2 surrounding the bearing sleeve 32 there is provided an annular chamber I28, which chamber is in constant communication with the bore 25 and pump inlet 26 through channel I 30 and openings 21. Said chamber I28 is also in constant communication with a series of ports I 32, I34 leading through the sleeve 32.

The right hand end of the piston 39 covers more or less of the ports I32, I34, depending upon its lateral (as shown in the drawing) position with respect to sleeve 32, and thereby controls communication between the pump outlet and the inlet 20 by way of chamber 29, ports I32 and I34, chamber I28, passage I30, and openings 21.

In the operation of the apparatus above described, the differential pressure corresponding to the mass air flow per unit of time urges the diaphragm and piston 39 to the right: while the fuel pressure differential across the jet system M, which is a measure of the rate of fuel flow to the engine, acts upon said piston to urge the latter to the left. Under normal conditions of operation, the piston will be in the position shown in Fig. 1, with communication established between outlet 22 and inlet 20 by way of chamber I28; since the pump capacity at any given engine speed is normally much greater than any fuel flow that would be required at that speed. If, now, the rate of air flow rises, the differential pressure in the chambers 88 and 90 becomes greater and shifts the piston 30 to the right, either into the position wherein back flow of fuel to the pump inlet is completely cut off, or into an intermediate position wherein said back flow is diminished. In either event, the fuel flow to the engine is increased, and the fuel differential pressure acting upon piston 39 is also increased. This increased fuel differential pressure urges the piston to the left, so that said piston comes to rest in a position wherein the force exerted on the piston by said fuel pressure differential balances that of the increased air pressure differtial. If, now, the air flow decreases, the fuelpressure differential moves the piston 30 further to the left, increasing the back flow of asoaoe a.

fuel to thexpumplinlet-{andi decreasingthe fuel flow to the engine, untilxthepiston "reaches: a postion wherein thexconsequent decreased. fuelpressure differential balances thediminished airpressure differential.

It will-thus be apparentthat; through the apparatus above described ,:there='is maintained a substantially .constantratio between-the fuelflow and the air flow. This ratio: may, of course, be varied by operation of the i mixture control valve 42.

It will also be apparent -that, through the above described apparatus, an increaseof pump discharge pressure when-the pistontilis inbalanced position will move said piston to the left from said position, allowing further flow of fuel back to the pump inlet and relieving said discharge pressure. Said piston continuesto open widerthelpath of return fuel flow through opsnings tfi t and I 32, until the pump dischargepressure. is reduced to such value that the fuel pressure diiferential is 'balanced by the air pressure differential; Thus, for a given air differential pressure the-pump discharge pressure is maintained substantiallyconstant; and this is achieved "through the same elements that maintain a substantially constant ratio betweenv thefue'l andair flows, and without the necessity of a separate pump discharge pressure relief valve as has heretofore been employed.

If desired, a spring MS may be provided for urging the diaphragm 8t to the right in Fig. .1 to insure that back flow of fuel through the relief passage 132 is restricted to any preferred extent when no air is flowing through the venturi mil or when the air differential pressure is verysmall, as for low rates of air flow corresponding to idlin positions of thethrottle.

The pressure of spring-i-40-on the diaphragm 85 may be adjustedas desired-by conventional spring-adjusting means-such as a nut M2 and screw M4.

Throughout the operation of the engine the piston 3t] is rotated continuously, so that static friction is eliminated between said piston and the bearing sleeve 32. The piston is thus enabled to respond with particular accuracy and precision to slight changes in the air and fuel pressure differentials.

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

I claim:

1. A fuel control system for internal combustion engines, comprising a fuel pump having a fuel inlet and a fuel discharge outlet, means for conducting fuel from said outlet, said conducting means including a jet system, means comprising a relief valve member for controlling a back flow of fuel from said discharge outlet to said fuel inlet, and means for subjecting opposite portions of said member to the fuel differential pres sure across said jet system.

2. A fuel control system for internal combustion engines, comprising a fuel pump having a fuel inlet and a fuel discharge outlet, means for conducting fuel from said outlet, a relief valve member subject on one face to the fuel discharge outlet pressure, a restriction in said conducting means, means for subjecting an opposite face of said valve member to the fuel pressure in said conduit means downstream-of said restriction, and means controlled by said =valve= member for the passage-of fuel from said discharge outlet back to said 'fuelinlet;

3. A fuel control systemfor internal combustion engines, comprising a fuel pump having a fuel inlet and a fuel discharge outlet, means for conducting fuel from said outlet, a restriction in said conducting means,- a valve member subject on one face to the fuel-discharge pressure of said pump, means controlled by said member in responseto an increase-in pump discharge pressure for relieving the latter by flow of fuel back to the pump inlet, means for subjecting the opposite-face of said valve member to fuel pressure in said-conducting meansdownstream of said restriction, and means-for applying'to said member a variable controlling force opposing the fuel pressure difierential acting thereon.

4-. A fuel-control system for internal combustion engines, comprising a fuel pump having a fu'elinletand a fueldischarge outlet, means-for conducting fuel fromsaid outlet, said conducting means having a restriction therein, a control casing having a port therein, a piston movable in said-casing and-cooperating with said port for controlling a back flow of fuel from said discharge outlet' to said fuel inlet, 1 said piston being subjected on-one face to the'fuel pressure at said pumpdischarge-outlet, means for "subjectingthe opposite face of said pistonto the fuel pressure at a point in said conducting means downstream of said-restriction whereby-opposite faces of said pistonare' subjected to the differential pressure of fuel-flowing through said conducting means, and in eansfor applying-to said piston a variable controlling force acting in a direction opposite to that of said fueldifferential pressure.

A fuel control system for internal combustion engines, comprisinga fuel pump having a fuel inlet and a fuel discharge outlet, means for*conducting 'fuelfrom-said outlet, said conducting means having a restriction therein, a control casing having a port therein, a piston movable in said casing and cooperating with said port for controlling a back flow of fuel from said discharge outlet to said fuel inlet, said piston being subjected on one face to the fuel pressure at said pump discharge outlet, means for subjecting the opposite face of said piston to the fuel pressure at a point in said conducting means downstream of said restriction whereby opposite faces of said piston are subjected to the differential pressure of fuel flowing through said conducting means, means for applying to said piston a variable controlling force acting in a direction opposite to that of said fuel differential pressure, nd means for continuously rotating said piston while said pump is in operation.

6. A fuel control system for internal combustion engines, comprising a rotary fuel pump, a fuel inlet and a fuel outlet for said pump, a fuel discharge conduit for receiving fuel from said outlet, a metering restriction in said discharge conduit, a pressure relief conduit con necting said outlet to said inlet, a cylinder having at least one port extending through a wall thereof, said cylinder and port forming a portion of said pressure relief conduit, a piston rotatably and slidably mounted in said cylinder adjacent said port so as to vary the opening of said port upon sliding movement, said pressure relief conduit including a portion subjecting the end of said piston adjacent said port to the pump discharge pressure, means for subjecting the opposite end of said piston to the pressure in said discharge conduit downstream from said restriction, and means drivingly connecting said pump and piston to cause continuous rotation of said piston during operation of said pump and thereby to prevent sticking of said piston during sliding movement thereof.

7. A fuel control system for internal combustion engines, comprising a rotary fuel pump, a fuel inlet and a fuel outlet for said pump, a pressure relief conduit connecting said outlet to said inlet, a cylinder having at least one port extending through a wall thereof, said cylinder and port forming a portion of said pressure relief conduit, a piston rotatably and slidably mounted in said cylinder adjacent said port so as to vary the opening of said port upon sliding movement, said pressure relief conduit including a portion subjecting the end of said piston adjacent said port to the pump discharge pressure, and means drivingly connecting said pump and piston to cause continuous rotation of said piston during operation of said pump and thereby to prevent sticking of said piston during sliding movement thereof.

8. A fiuid flow control system, comprising a rotary pump, an inlet and an outlet for said pump, a discharge conduit for receiving fluid from said outlet, at metering restriction in said discharge conduit, a pressure relief conduit connecting said outlet to said inlet, a cylinder having at least one port extending through a wall thereof, said cylinder and port forming a portion of said pressure relief conduit, a piston rotatably and slidably mounted in said cylinder adjacent said port so as to vary the opening of said port upon sliding movement, said pressure relief conduit including a portion subjecting the end of said piston adjacent said port to the pump discharge pressure, means for subjecting the opposite end of said piston to the pressure in said discharge conduit downstream from said restriction, and means drivingly connecting said pump and piston to cause continuous rotation of said piston during operation of said pump and thereby to prevent sticking of said piston during sliding movement thereof.

9. A fluid flow control system, comprising a, rotary pump, an inlet and an outlet for said pump, a pressure relief conduit connecting said outlet to said inlet, a cylinder having at least one port extending through a wall thereof, said cylinder and port forming a portion of said pressure relief conduit, a piston rotatably and slidably mounted in said cylinder adjacent said port so as to vary the opening of said port upon sliding movement, said pressure relief conduit including a portion subjecting the end of said piston adjacent said port to the pump discharge pressure so that said discharge pressure acts on said piston in a direction to increase said port openings, means for applying a controlling force to said piston in opposition to said discharge pressure, and means drivingly connecting said pump and piston to cause continuous rotation of said piston during operation of said pump and thereby to prevent sticking of said piston during sliding movement thereof.

MILTON E. CHANDLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,165,447 Brown July 11, 1939 2,223,381 Mock Dec. 3, 1940 2,263,091 Johnson Nov. 18, 1941 2,330,558 Curtis Sept. 28, 1943 2,334,679 Mason et al Nov. 16, 1943 2,348,113 Davis May 2, 1944 2,353,871 Bowen July 18, 1944

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