US2456603A - Fuel supply system - Google Patents

Description

Patented Dec. 14, 1948 FUEL SUPPLY SYSTEM Frederik Barfod, South Bend, Ind., assignor to BendixAviation Corporation, South Bend, Ind., a corporation of Delaware Application May 7, 1945, Serial No. 592,397

40 Claims. (Cl. 12S-119) 'I'his invention relates to fuel supply systems or devices for internal combustion engines and more particularly to devices or sysi Ans in which liquid fuel is supplied under positive pressure.

An important object of the invention is to provide a fuel feeding system in which the fuel flow is automatically regulated in accordance with certain engine variables such as, for example engine speed and engine. charging pressure.

This fuel supply system, whileespeclally applicable to fuel supplyV systems of thecharacter hereinafter particularlydescribed, ls not limited to such uses. but is obvious-.11,"l available, with or without modification, in aI great-variety oi' cases where fuel is intended to be supplied under more or less analogous conditions in an internal combustion engine or otheri'uel consuming device.

Further objects and advantages of the invention will be apparent, to those skilled in the art, from the following detaileddescription, taken in connection with the accompanying drawing. Although but oneembodiment is shown, skilled persons will understand that many variations may be made without departing from the principles disclosed, and I contemplate the employment of any structures, arrangements, or modes said` chamber 34 is being at all times substantially the same as that in passage 33, and this pressure in said chamber and passage being hereinafter referred to as pressure A or control pres'- sure. One wall of chamber 34 is closed by a ilexible diaphragm 36 which is marginally clamped between the casing 36 and a. shoulder of the body 40 of the device. A restriction or jet 42 is provided between the passages 32 and 33 through which fuel is adapted to ow.

Passage 32 is provided with a branch passage 44 which communicates with the impeller chamber 46 of a pump, indicated generally at 41. 'I'his pump, as shown, is of the centrifugal type which includes an impeller I46 driven by they engine through a shaft di) which is suitably connected,

by any well known means, with said engine which system.

of operation that are properly within the vscope f of the appended claims. l

In the figure, which is a diagrammatic view of a fuel system embodying the present invention, there is shown an induction passage l@ having an air inlet l2, and a mixture outlet lt connected to the intake manifold l@ of an internal combustion engine, not shown, or to a supercharger inlet, should a supercharger be used, the induction passage i@ being controlled by a throttle valve I8. A supercharger might alternately be connected to the inlet l2 or such a device might be connected to` both,` the inlet' I2 and the outlet lli. Liquid fuel is Supplied by a pump, indicated generally at 20, which may be Operated by the engine, or by any other suitable means, and is capable of supplyingfuel under positive, preferably but not necessarily substantially constant, predetermined pressure. This pump may be of any wel] known type but, as shown, is of the sliding vane type having an inlet 22 receiving fuel from a source, anoutlet conduit 24 and The outlet of pump 4l is connected to a passage 52 which communicates with a chamber 54 on the side of the diaphragm 38 opposite the chamber t4 by way of a metering restriction or iet 56 therein, the pressure of fuel in said chamber 58 being at all times substantially the same as that in the passage 52 posterior to the jet 56 and this pressure in chamber 5d and passage 52 posterior to jet 56 will be hereinafter referred to as pressure B or metered fuel pressure.

Chamber 5d has an outlet connected by a conduit 53 with a fuel nozzle member 6d discharging into the induction passage posterior to the throttle valve. Air is bled into the nozzle member 66 through cross passages 6I in a tip portion 62 of an air tube 63 having an air passage 63a therein receiving air from a tube 64 by way of a passage 65; the tube 64 being located in the air entrance I2 of the induction passage and adapted to receive the impact of air entering said induction passage Tip portion 62 extends part way into the fuel passage of the nozzle and the fuel emulsion is discharged from an annular groove 66 between the shoulder at the base of said portion 62 and the adjacent end of nozzle member 60. The outlet for the chamber 54 is provided with a fitting 61 having a bore within which a iiat sided or uted valve 68 is slidably guided, said valve having a conical tip 69 cooperating with a` valve seat 'l0 in said fitting for controlling the discharge of fuel from chamber 64. The

end of the valve v68 opposite the conical tip is attached tothe diaphragm 38. As shown, said attached end is riveted over at 1| and washer-like ing cut or otherwise injured thereby and providing means for retaining the adjacent ends of springs 16 'and 18 disposed respectively in chambers 54. and 34. These springs are preferably light and of substantially the same calibration although they may have other characteristics. Spring 16 reacts between the"spring retainer 1 4 and one wall of the chamber 54 for urging the valve 68 in the opening direction, while spring 18 reacts between retainer 12 and a spring retainer 8|) disposed in chamber 84, said spring being adapted to urge the valve 68 in the closing direction. The Veffective force of the springs is adjustable, a screw 82, threadably received in an opening in the casing 36, being provided therefor. It is to be understood that preferably the adjustment is such that the valve 68 is normally slightly open when the engine is inoperative, for a purpose to be described hereinafter.

-The passages 52 and 33 are connected together by a conduit 86. One end of said conduit communicates with the passage 52 anterior to the restriction 66 and the other end communicates with the'passage 33, there being a restriction or orice 88 provided in the conduit 86. It is to bel noted that the fuel pressure in that portion of conduit 86 which is on the centrifugal pump side of orice 88, that is between orifice 88 and conduit 62, is at all times substantially the same as the pressure in that portion of the passage 52 anterior to jet 56 and the pressure in said portions of the c'onduit and passage will be hereinafter referred to as pressure C.

Means for varying the effective size of orifice 88 comprises a valve 92 controlled by a suction responsive device indicated generally at 93. The valve 92 is connected to or' formed integral with a valve stern 94 slidable in a guide .96, said stern 94 being connected at-its outer end to a plate'98 forming one wall of a sealed expansible bellows enclosed by a casing |02 which is supported on the body 40 by any suitable well known means. The casing is subjected to engine charging pressure by means of a conduit |06 which communicates with said casing adjacent the lower portion thereof so as to draw oi any fuel which may seep past the stem 94, and communicates with the induction passage posterior to the throttle valve I8, as shown. However if a supercharger is used conduit |06 is connected to the engine manifold, posterior to the supercharger. The valve 92 is therefore controlled in accordanse with engine charging pressure which reflects throttle position and engine speed and load. A light compression springv |08 may be provided within the bellows, an arrangement that ls particularly desirable, if the bellows is partially or completely evacuated, to extend the bellows to a normal balancing position and it may be desirable for said spring and bellows to be so calibrated and arranged that the valve 92 will be normally closed when the pressure in the casing |02 is at its highest operating value.

It is also to be noted that the pressure in branch passage 44 is at all times substantially the same as that in passage 32 and the pressure in said passages will be hereinafter referred to as pressure D or pump inlet pressure.

Operation During normal operation fuel is supplied under pressure to the inlet 44 of the centrifugal pump 41 by means such as the fuel pump 20 although 'other means may also be employed to supply fuel to said inlet 44. Fuel received by pump 41 is discharged under an increased pressure into passage 52 from which it flows through metering orifice 56 to chamber 54, past valve 61 which is opened by the pressure of fuel in chamber 54 acting on diaphragm 38, into conduitv 58, and thence to a nozzle 60 or other fuel discharge means Due to the inherent characteristics of the centrifugal pump 41, the pressure C at the outlet of pump 41 will be greater than the pump inlet pressure D by an amount which is directly proportional to the square of the speed of the pump and consequently directly proportional to the square of the engine speed.

During operation, with Vthe valve 92 in a partially open position, fuel at pressure C will flow through the calibrated restriction 88 into passage 33 and then through orifice 42 to the pump inlet 44. As a consequence the pressure in passage 33, herein referred to as control pressure A, will be of a value intermediate the fuel pressure C and pump inlet pressure D, and its value relative to the pressures C and D will depend upon the effective size of orifice 88 relative to the area of orifice 42. For any fixed setting of valve 92, pressure A will remain greater than pressure D and less than pressure C by amounts representing constant percentages of the difference between pressures A and D. Thus, if orifice 88 has an effective area equal to orifice 42, pressure A will remain substantially half way between pressures C and D irrespective of variations in speed of pump 41. It therefore follows that the differential between pressures C and A will likewise vary as the square of engine speed, for a fixed setting of valve 92.

Since the springs 16 and 18 are substantially in balance, exc'ept for considerations hereinafter explained, the pressure of the fuel in chamber 54, referred to herein as metered fuel pressure B, will be maintained equal to control pressure A. In the event pressure B should tend to exceed pressure A the valve 61 will tend to open to allow the escape of additional fuel to the nozzle and consequent lowering of pressurev B, and the reverse action will occur if B tends to be less than A. It is thus clear that the difference between pressure C and pressure B likewise will vary as the square of the enginespeed for a given setting of Valve 92.

As is generally known, the quantity of fuel which will flow through a given size metering orifice such as metering jet 56 will vary in proportion to the square root of the differential in pressures C and B on opposite sides of the orifice, and since this differential varies as the square of the engine speed, it will be apparent that the quantity of fuel flowing through orilc'e 56 for a given setting of valve 92 will vary directly as the engine speed.

In view of the fact that the weight of air ow to an engine at a given manifold pressure varies substantially in direct lproportion to the engine speed,. except for variations caused by Variables such as exhaust back pressure and in- I take air and exhaust lpending application of Wirth and Barfod, Serial vneedle contour is such as to increase the orifice Vfuel mixture as is desired. One means for effectl gas temperatures which may be compensated for'as described in the co-l No. 607,290, filed June 7, 1945, the device here described will supply fuel to the -engine in acl cordanc'e with the air flow thereto.

If at a. given engine speed the manifold or engine charging pressure is increased, the weight of air supplied to the engine will likewise increase, andthe quantity of fuel suppliedto the engine should be correspondingly increased. This increase in fuel flow is accomplishd in the present device by the operation of valve 92. Any increase in charging pressure is transmitted, through passage |06 to chamber |02 and will lr, cause bellows |00 to partially collapse whereupon valve 92 will reduce the effective area of the calibrated restriction 88. Y

Upon decrease in the effective area of orifice 88, pressure A will be reduced so as to more nearly approach pressure D and as a consequence the valve 61 will open to permit discharge of fuel t0 the engine at a greater rate such that thel pressure B will be reduced to equal new pressure A. In other words, reducing pressure A reduces pressure B and thereby increases the differential between fuel pressure C and metered fuel pressure B. Consequently, fuel is delivered through orifice 56 at a greater rate to compensatefor the increase in air flow which instigated the change in pressure A. By properly contouring valve 92, the effective area of orifice 88 may be so controlled as to obtain any desired fuel to air relationship with variations in engine charging pressure. :if

For example, at conditions of high power output, corresponding to low intake manifold pressure it is generally desirable to increase the richness of the mixture. This may be readily accomplishecl by properly shaping the contour of valve i' 92. If the valve 92 is arranged to maintain the effective area of the metering orifice directly proportional to the manifold pressure, a constant mixture ratio will be obtained. However, if the cation, Serial No. 607,290.

Provision may be made for enriching the idling ing idle enrichment is to adjust valve 6l so that 60 it is normally slightly open. Thus the fuel metering differential pressure required to balance the diaphragm valve assembly is increased. Then at low differential pressures, corresponding to idle operation, the arrangement is of material effect in producing a relatively large increase in fuel flow, thereby providing the dcsired rich mixture at idle. However, at high differential pressures the arrangement has a negligible effect and has substantially no effect on the richness of the fuel mixture which is maintained at the normal fuel to air ratio.

It is thus apparent that the basic structure will provide a substantially constant mixture richness. but by introducing an extraneous factor to effect variations in the position of valve Olas by varying the area of the metering orifice IB, any fuel metering characteristic may be obtained. Means other than pump 41 might also be used to create a pressure in passage 52 which varies as the square" of engine speed, or other changes might be made without departing from the principles of the invention and I contemplate the use of any such arrangements properly falling within the scope of the subjoined claims.

I claim: v

1. In a fuel system fer an internal combustion engine: a source of fuel; a conduit connecting said source of fuel with the engine; a pump for creating a fuel pressure and effecting a flow of fuel through said conduit, the quantity of which will vary directly as the engine speed; means for controlling said flow; and a passage adapted to transmit a variable controlpressure developed by said pump to said means for influencing the vsource of fuel; a conduit for connecting said source of fuel with the engine; a pump in said conduit adapted to be driven by the engine;

means for creating a fuel pressure in and effecting a flow of fuel through said conduit, the quantity of which will vary directly as the speed of said engine; means for controlling said fuel flow; and means for regulating the first mentioned means.

4. The invention defined by claim 3 wherein the regulator means is responsive to an engine variable.

5. In a fuel system for an internal combustion engine: a conduit for supplying fuel to the engine; fuel metering means in said conduit; fuel flow vcontrol means posterior to the metering means; means, having an inlet and an outlet, for supplying unmetered fuel to said metering means at a pressure varying in response to variations in engine speed; meansfor creating a pressure in-` termediate the pressure of said unmetered fuel and the inlet pressure; means for subjecting the fuel flow control means to fluid pressure posterior to the metering means, and to the intermediate pressure acting in opposition to said fluid pressure; and means for varying the intermediate pressure.

6. The invention defined by claim 5 wherein the last mentioned means is responsive to an engine variable.

7. The invention defined by claim 5 wherein the last mentioned means is Iresponsive to engine charging pressure.

8. The invention defined by claim 5 wherein the engine has an intake manifold and the last mentioned means is responsive to the manifold pressure.

9. A fuel system for an internal combustion engine comprising aconduit for supplying fuel to the engine; fuel metering means in said conduit; fuel control valve means for said conduit posterior to the metering means; a pump adapted to be driven by the engine and having an inlet and outlet, for supplying unmetered fuel to said metering means at a variable pressure; means for creating a fuel pressure intermediate the pressure of said unmetered fuel andthe inlet pressure; means for subjecting the valve means to fluid pressure posterior to the metering means,

audace and to the in termediate pressure acting in opposition to said iiuid pressure; and means for vary,

ing'the intermediate pressured 10. The invention defined by claim 9 wherein the last mentioned means is adapted to temporarily vary the intermediate pressure.

11. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to the engine; fuel metering means in said conduit; fuel flow control means posterior to the metering means; 'an engine driven pump for supplying fuel to the metering means at a pressure varying in response to variations in engine speed; means for transmitting a variable control pressure created by said pump tosaid fuel flow control means; means for controlling the fuel flow control means by the differential of the pressure posterior to the metering means and said control pressure; and means for varying one of the pressures actingon said fuel ow control means.

12. The invention defined by claim 11 wherein the last mentioned means temporarily causes a l diierential in said pressures.

13. A fuel supply system for an .internal combustion engine comprising a conduit for supplylng fuel to the engine; a metering jet'in said conduit; a valve posterior to the jet; for controlling the flow of metered fuel; pump means for supplying fuel to the metering jet at a pressure varying in accordance with engine speed; means for creating a control pressure; means for subjecting the valve to metered fuel pressure for urging said valve in one direction, and to said control pressure for urging the'valve in the opposite direction; and means for varying one of the effective pressures controlling said valve.

14. In a fuel system for an internal combustion engine: ,a conduit for supplying fuel to the engine; a metering jet in said conduit; a regulating valve posterior to the metering `jet for controlling the flow of metered fuel; means for supplying fuel to the metering jet at a pressure varying in accordance with engine speed; means for creating a control pressure which is normally equal to the metered fuel pressure; means for subjecting the valve to metered fuel pressure for urging said valve in the opening direction and to said control pressure for urging said valve in the closing direction; and means for at least temporarily unbalancing the pressures controlling said valve. l

15. In a fuel system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering restriction in said conduit; a valve in said conduit posterior to said restriction; a diaphragm connected with said valve; pressure creating means having an inlet, and an outlet supplying fuel to said conduit anterior to the metering restriction at a pressure varying in accordance with engine speed; a source of fuel connected with said inlet; means for creating a uid pressure intermediate the inlet and outlet pressures of the pressure creating means; means for subjecting the diaphragm to uid pressure posterior to the restriction and said intermediate pressure for urging the diaphragm in the valve opening and closing directions respectively; and means for varying said intermediate pressure.

16. In a fuel supply system for an'internal combustion engine having an intake manifold controlled by a throttle: a conduit for supplying fuel to the manifold; a metering jet in said conduit; a valve in the conduit posterior to the jet; a uuid pump having an inlet, and an outlet supplying fuel to the conduity anterior to the Jet at a pressure varying in accordance with engine speed; a source of fuel connected to the inlet; means for creating a fluid pressure normally balancing the metered fuel pressure; means for subjecting the valve to the metered fuelI pressure and the balancing pressure for urging the valve in the opening and closing directions respectively; and means responsive to manifold pressure posterior to the throttle for varying one of said preslll'; sures.

l. 17. 'Ijhe invention defined by claim 16 wherein the lastqnentioned means temporarily varies the balancingipressure.

18 A fuel supply system for an internal cornbustion engine having an intake passage with a fuel discharge nozzle therein comprising a conduit for supplying fuel to the nozzle; a metering jet in said conduit; a valve posterior to the jet for controlling the flow of metered fuel; pressure creating means having an inlet and an outlet supplying unmetered fuel to the conduit anterior to the jet at a pressure varying in accordance with engine speed; means for urging the valve in the opening direction in accordance with lmetered fuel pressure; means for urging the valve in the closing directionl in accordance with fluid pressure intermediate the pressure of unmetered fuel and inlet pressure; and means for varying the pressure urging the valve in the closing direction.

19. In a fuel supply syst-em for an internal combustion engine: a conduit for supplying fuel to the engine; metering -means in said conduit; a`

valve posterior to said means for controlling the flow of metered fuel; a movable wall connected to said valve and subjected to metered fuel pressure for urging the valve in the opening direction; a pump in said conduit having an inlet and an outlet, and so constructed and arranged as to create a head across said metering means pro- 40 portional to the square of engine speed; a source of fuel connected with said inlet; a passage connecting the outlet of said pump anterior tothe metering means with said inlet; a restriction inv said passage; valve means for varying the'eifec- '4" tive area of said restriction; means responsive to the density of the charge entering the engine to control said valve means; a, second restriction in said passage on the inlet side .of the iirst H mentioned restriction; and means for subjecting the movable wall to the pressure of fluid between said restriction/sffwlereby said wall is urged' inl the valve closing direction.

20. In a fuel system for an internal combustion r engine: a conduit for supplying fuel to the engine; ametering jet in said conduit; a valve posterior to the jet for controlling the flow of metered fuel; means having an inlet supplied with fuel and an outlet for supplying unmetered fuel to the jet, said means being adapted to create unmetered fuel pressure greater than the inlet pressure by an amount substantially proportional to the square of engine speed; a diaphragm connected with said valve, said diaphragm being subjected 6,. to metered fuel pressure for urging the valve in the opening direction; a passage connecting said inlet and outlet; a pair of spaced restrictions in said passage, the pressure intermediate said restrictions being a control pressure of a value intermediate the outlet pressure and the inlet pressure and greater than the inlet pressure by an amount equal to a constant percentage of the difference between said outlet pressure and the inlet pressure; means for subjecting the diaphragm to' the control pressure for urging the valve in 9 the closing direction and means for varying the effective area of one of Suid restrictions.

21. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering jet in the conduit; a valve posterior to the jet for controlling the flow of metered fuel; an engine driven pump having an inlet supplied with fuel, andan outlet for supplying fuel to the metering jet at a pressure varying as a function o f engine speed; a diaphragm connected to said valve and subjected to metered fuel pressure for urging the valve in the opening direction; means for creating a control pressure substantially equal to the metered fuel pressure; means for subjecting the opposite side of the diaphragm to the control pressure; and means for at least temporarily varying the control pressure. Y

22. The invention deflned by claim 21 wherein the last mentioned means is responsive to changes in the density of the charge entering the engine.

23. The invention defined by claim 21 wherein a rise in the charge density entering the engine will effect a drop in the control pressure.

24. The invention defined by claim 21 wherein the last mentioned means is controlled by the density of the charge entering the engine and is adapted to effect an increase in the flow capacity upon an increase in the pressure of said charge.

25. The invention defined by. claimv 21 wherein there is a. pair of springs on opposite sides ofthe diaphragm acting in opposition. to each other.

26. The invention defined by claim 21 wherein there is a yielding means on each side of the diaphragm acting in opposition to each other on said diaphragm, the respective yielding means normally balancing each other. I,

27. 'I'he invention' defined by claim 21 wherein there is a spring on each side of the diaphragm acting in opposition to each other on said diaphragm, said springs normally balancing each other; and adjusting means adapted to establish the normal position of the valve.

28. The invention defined by claim 21 wherein there is spring means on each side of the diaphragm acting in opposite directions on said diaphragm, said springs normally balancing each other and normally maintaining the valve in a opened position.

29. In a fuel system for an internal'combustion engine: a fuel supply pump; a connection for conducting fuel from the pump to the engine; means including a pumping member driven by the engine for delivering fuel to the engine in accordance with variations in engine speed;

' means for varying the fuel flow to the engine as provided by the first mentioned means; a passageway for transmitting a variable fuel control pressure created by the first mentioned means to the varying means; and means for varying the control pressure as a function of' an engine variable.

30. A pressure carburetor for an internal combustion engine, said carburetor having an induction passage anda source of fuel under pressure:

an engine driven pump which receives fuel from said source and generates pressure in proportion to the square of revolutions per minute of the engine; a conduit from the pump to the induction passage; a metering orifice in said conduit; a movable wall; means for admitting fuel to one side of the wall; a restriction in said means; a fuel chamber associated with the movable wall on the opposite side thereof in which metered fuel pressure is maintained; a valve controlling the outlet from the chamber; and means responsive to the charging pressure of the engine for effecting control of the position of said valve.

31. In a fuel supply system for an internal combustion engine having an intake manifold controlled by a throttle: a fuel pump adapted to deliver fuel at a substantially constant pressure; a conduit connecting said fuel pump with the induction passage posterior to the throttle: a metering jet in said conduit; a valve posterior to the metering jet forcontrolling the flow of fuel; a diaphragm connected to the valve; a metered fuel chamber on the valve side of the diaphragm; a second'fuel chamber, on the opposite side of said diaphragm: opposed balanced springs in said chambers urging the diaphragm in oppositey directions; an engine driven pump. including a rotor, adapted to produce an increase in pressure of unmetered fuel proportional to the square of engine speed; a fuel passage connecting the outlet and inlet sides of' the pump; a pair of restrictions in the fuel passage arranged in series; means connecting the second chamber with said fuel passage intermediate said restrictions; a valve controlling the effective area of the restriction directly subjected to unmetered fuel pressure; and a bellows controlling said `valve in accordance ,with the pressure in the intake manifold posterior to the throttle.

32. The invention defined by claim 31 and including a fuel nozzle in the induction passage; and means for bleeding air to said nozzle,

33. A fuel feeding device'for an engine, comprising a. fuel conduit having a fuel metering orifice therein, a centrifugalpump in the conduit adapted to be rotatably driven by the engine for increasing the pressure of the unmetered fuel `supplied to the orifice with increase in engine means for increasing the metering differentialy pressur'e across said orifice with increase in engine load, said last named means comprising a valve in the conduit posterior to the orifice for varying the metered fuel pressure in accordance with `a variable representative of variations in engine load at a given engine speed.

35. In a fuei feeding device for an engine, a'y main fuel conduit for supplying fuel to the y engine, a fuel metering orifice therein, a fuel pump having a fuel inlet for receiving fuel from a source and an outlet for supplying fuel to the orifice under a pressure greater than the pressure in the inlet by an amount varying substantially as the square ofthe pump speed, a by-pass from the pump outlet to the pump inlet having two restrictions in series therein, a fuel control valve in the conduit posterior to the metering orifice,

a movable pressure responsive wall connected to said valve and arranged to be subjected `to the pressure in the by-pass between the vrestrictions for urging the valve toward closed position and to the'pressure of the metered fuel for urging the valve toward open position, and valve means for varying the effective varea of one of said restrlctions. 1

36. In a fuel metering device for an engine: a main fuel supply passage having in series therein a centrifugal impeller adapted to be driven by the engine, a metering orice, and a flow control valve, said impeller varying the pressure on the upstream side of the metering orifice with variations in speed of the impeller; a by-pass passageway leading from the fuel supply. passage between the impeller and orice to the fuel supply passage anterior to the impeller, said passageway having two restrictions in series therein; and a member responsive to the pressure in the passageway between the restrictions for controlling said now control valve.

37. The fuel metering device dened in claim 36 comprising in addition a valve means for varying'` the relative effective areas of the two restrictions, and a device responsive to variations in the pressure of the air supplied the engine for controlling said valve means.

38. A fuel metering device for an engine comprising a centrifugal impeiler adapted to be driven by the engine, a fuel inlet passage for supplying fuel to the impeller, an outlet passage into which the impeller discharges fuel under a pressure varying with variations in impeller speed, a metering crice in thenoutlet passage, a conduit connecting the outlet passage anterior to the metering orifice to the inlet passage, two

restrictions in series in said conduit, and a valve l30 2,374,844

in the outlet passage posterior to the metering orifice responsive to the pressure in the conduit between said restrictions.'

39. The invention ldefined in claim 38 comprising in addition a member for varying the eiec- 35 tive area of one of said restrictions.

40. In a fuel feeding device for an engine or the like: a centrifugal pump adapted to receive fuel through an inlet from a source and to discharge said fuel into a passage, a metering oriilce in the discharge passage, a valve in the passage posterior to the orifice, a passageway interconnecting the discharge and inlet of the pump and having two calibrated restrictions in series therein. means responsive to variations in the pressure in said passageway between the restrictions for'controlling said valve, a main control element for controlling the energy output of the engine or the like, and means operated in response to conditions vobtained by the movement of said element for varying the effective size of one of said restrictions.

FREDERIK BARFOD.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,189,705 Chandler Feb. 6, 1940 2,290,921 Udale July 28, 1942 2,303,998 Holley, Jr. Dec. 1, 1942 2,324,599 Schorn July 20, 1943 2,372,356 Chandler -..'Mar. 27, 1945 Stokes May 1, 1945 FOREIGN PATENTS Number A y Country Date 429,682 y Great Britain June 4, 1935 Certicate of Correction Patent No. 2,456,603. December 14, 1948.

FREDERIK BARFOD It is hereby certified that errors appear in the printed specication of the above numbered patent requiring correction as follows:

Column 4, lines 13 and 53, column 5, lines 22 and 61, column 6, line 2, for valve 67 read valve 68; line 28, claim 3, after engine str ike out the semi-colon; line 29, strike out the word means; column 12, line 7, claim 40, after discharge insert passage;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent OHice.

Signed and sealed this 7th day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommsszoner of Patents.

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