US2443527A

US2443527A - Fuel supply system

Info

Publication number: US2443527A
Application number: US689712A
Authority: US
Inventors: Emil O Wirth; Barfod Frederik
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1946-08-10
Filing date: 1946-08-10
Publication date: 1948-06-15
Anticipated expiration: 1965-06-15

Description

June 15, l

E. o. WIRTH ET .AL

FUEL surrLY SYSTEM Filed Aug 1' 1946 Wa ATTMA/fr '-Pateneauune 15,;948

j l i 2,443,527

UNITED y STATES PATENT (OFFICE FUEL SUPPLY SYSTEM Emil O. Wirth and Frederik Barfod, South Bend, .el

Ind., assignors to Bendix Aviation Corporation, South Bend, Ind., a' corporation of Delaware 'Application August 10,1946, serial No. ssauz y 1s claims. (c1. 12s-119) The present invention relates to fuel supply systems for internal combustion engines, burners o r the like and more particularly to a fuel system wherein liquid fuel is delivered to the engine under superatmospheric pressure.

An object of the present invention is to provide a fuel supply system for an internal combustion engine or the like wherein the ratio of fuel-to-air mixture delivered to the engine is determined by certain engine operating variables.

Another object of the invention is to provide a fuel supply system for internal combustion engines in which the quantity of fuel delivered to the engine is regulated by the same engine operating variables as those controlling the quantity of air entering the engine.

Another object is to provide a simple though highly reliable fuel metering device for an engine in which a controlled supply of fuel to the engine is obtained by regulating the effective fuel metering head across a metering `iet in accordance with variations in engine speed and throttle position.

Further objects and advantages will'be apparent to those skilled in the art from the following description of our invention in its broader aspects and in a specific detailed embodiment thereof.

Although the drawings and detailed description disclose but one specific embodiment of our fuel metering device, it isto be understood that many variations in structure and in arrangement of elements comprising our device are possible without departure from the invention and we contemplate the use of any such variations that properly fall within the scope of the appended claims.

The foregoing objects and advantagesr are accomplisl'led` by including in a fuel supply system a gear pump and associated by-pass valve adapted to deliver fuel at a substantially constant pressure, a centrifugal pump driven at a speed relative to engine speed for receiving fuel from the gear pump and delivering it at an increased pres-A sure to a metering unit having a series -of metering orifices therein, at least one of which is controlled by a manually actuated valve; and a valve controlled n-ozzle regulated by variable fluid pressures for controlling 'the discharge of fuel into the air stream entering the induction passage of the engine. A manually actuated three-Way valve is also included in the system to provide a means for idle cut-off and for enriching the fuel-to-air mixture while the engine is being started.

While the present fuel metering device may be used to supply combustible mixtures to a variety of fuel consuming devices,` for example, burners' and internal combustion engines, for convenience of description the word engine will be used hereinafterin referring to these devices collectively and is intendedto embrace any or all devices in which it is desirable to meter fuel in accordance with air owing thereinto. The term induction passage `as used throughout the specification and in the appended claims includes any or all passageways leading to the engine through which air or air-fuel charging mixtures flow during operation of the engine.

In Figure 1 of theV drawings, the present fuel metering device with the various elements so ar-` ranged as to clearly illustrate the operating relationship existing therebetween is shown diagrammatically.

In Figure 2, the /main fuel control `valve is shown in idle vcut-on position.

In Figure 3, the main fuel control valve is shown in engine starting position.`

Shown generally at III in Figure 1 is a carburetor body having an induction passage I2 therethrough and a throttle valve I4 disposed therein for controlling the quantity of. air admitted into an internal combustion engine or other fuel consuming device, not shown. A controlled supply of liquid fuel is delivered to said induction passage by a fuel metering assembly, broadly consisting of a pump I6 provided with-a valve controlled by-pass I8 for delivering fuel at a substantially constant pressure, a centrifugal pump 20, a manual mixture control valve unit 22 through which fuel from said centrifugal pump is delivered to a fuel metering jet or orifice 24, 'and a pressure responsive fuel discharge valve unit 26 for discharging metered fuel into induction passage I2 infaccordance with the speed of the centrifugal pump 20 and with the position of throttle valve Il.

Although pump I6 may be any well known type,

as shown in the drawings it is a gear pump having intermeshing gears 3.0 and 32 mounted on shafts 34 and 38 respectively which yare journaled.

in pump housing 38, the gears being driven by the engine through shaft 36 and any suitablev driving means connected to or mounted on the free end of shaft 36. In the operation of pump I6, fuel is drawn from inlet conduit 40 and discharged into conduit l2 which communicates with centrifugal pump 20 through conduit A2', a three-way valve Il and -conduit 46. The pressure of the fuel delivered to the centrifugal pump is maintained at a substantially constant value by a valve controlled pumpl by-pass I8 which 'spring 68 on stem 54 adapted to react between disc 50 and guide 56 and to urge disc 50 to its closed position over orifice 52.

Centrifugal pump 20 which is adapted-to receive fuel from conduit 48 and to discharge it at an increased pressure into conduit 60 leading to control valve 22 consists of an impeller 62 having blades 64 disposed in chamber 66 and mounted on shaft 68 which is -journaled in pump housing 38 and connected directly to one end of shaft 86 of gear pump I6. Said impeller is driven by the engine through shafts36 and 68 at'a speed directly proportionalto the R. P. M. of the engine to build up an outlet pressure for the metering head across metering j et 24, the effective metering head being the difference between fuel pressures in conduit 60' and chamber 10, the latter of which is controlled either by the inlet pressure of the centrifugal pump or that of the gear pump, as

' will be fully explained hereinafter.

Manual mixture control valve unit 22 which is shown mounted on carburetor body I adjacent the throttle valve consists of a chamber 12 adapted to receive fuel from conduit 60 and an orifice 14 for admitting fuel at a reduced pressure into chamber 16. A tapered valve 18 joined toor formed integrally.J with a fluted valve stem 80 slidably received in valve guide 82 controls the effective size of orifice 14. In the present embodiment of the invention, valve 18 is regulated by the throttle valve actuating mechanism, not

shown, mounted on the free end of a throttle valve shaft 84 and operatively connected -to said mechanism through valve stem 80 and cam 86 mounted on the end of throttle valve shaft 84 and rigidly secured thereto by nut 88. Fuel impermeable diaphragm 80 which is constantly urged in the direction to open valve 18 by the pressure of the fuel admitted through orifice 14, forms one wall of chamber 16 and is marginally clamped between two sections of the control valve unit. The diaphragm 90 is provided with stiiening members 82 and 84, both of which have their edges turned outwardly relative to diaphragm 00 to prevent injury to said diaphragm by any rough edges or burrs on said members. The end of valve stem 80 is riveted `around centrally located apertures through the two stiftening members, diaphragm 90 and a stiffening'disc 96 placed on stiffening member 92 to rigidly se'- cure the valve stem thereto. Chamber 'I6 communicates through conduit 60' and calibrated metering orifice 24'with chamber 10 in discharge valve unit 26. I

Although in the embodiment shown in the drawings two metering orifices in series are ineluded, only one metering orifice regulated by asuitable valve for varying the effective size thereof is essential to the present metering device. The two orifices have been provided, however, to make possible the use of a valvular controlled orice of a -diameter much larger than that required lfor metering in order to achieve greater accuracy in the metering of the fuel. Further,

it is often necessary in adjusting a fuel metering device to change the metering jet, and in the` present modification of the invention, this Ycan readily be done by changing orifice 24, whereas if only the valvular controlled-orifice were employed, the orifice and valve or the entire mixture control unit 22 would have to be changed.

The discharge valve unit 26 is adapted to maintain the pressures therein at substantially constant predetermined values and is provided with a discharge nozzle 91 for discharging liquid fuel into theinduction passage posterior to throttle valve I4. The discharge of fuel through the nozzie is controlled by valve 98 which is formed integrally with a fluted or flat sided valve stem |02 slidably received in guide |04 and is adapted to seat over orifice |00 in said nozzle. The end of stem |02 opposite the valve is attached to a fuel impermeable diaphragm |06 which is marginally clamped between two sections of the casing comprising the discharge unit 2,6, and is adapted to fluctuate in response to any changes in pressure however small on either side thereof. The fluctuation of diaphragm |06 causes valve 90 to vary the effective size of orifice |00 and consequently to vary the discharge of fuel therethrough sothat the pressure in chamber 10 is maintained substantially constant and equal to the fluid pressure and effective force, of spring `|01 in chamber |08 on the opposite side of diaphragm |06. Said diaphragm is provided with stiffening members ||0 and |I2 secured in place on either` side of the diaphragm by riveting the end of reduced portion ||4 of stem |02 extending through centrally located holes in said members and in a stiifening disc ||6. It is noted that stiifening members have their edges turned outwardly relative to the diaphragm to provide a smooth corner over which said diaphragm may bend. Chamber |08 communicates through conduit H8, restriction ||9 and valve 4'4 with either-the fuel passageway 42 between gear pump I6 and centrifugal pump 20 for periods of normal operation or with the fuel passageway |20 anterior to the gear pump during other periods, as in starting. The pressure in chamber |08, therefore, will be equal to the pressure in conduit 42 during normal operation of the engine and equal to the pressure in conduit |20 during starting. inasmuch as the pressure in. conduit 42' is maintained at a substantially constant value by pump by-pass valve 50, the pressure of the fuel in chamber |08 will remain substantially constant during normal operation of the engine, and the total effective force tending to close valve 98 will be sum of the forces exerted by the fluid pressure in chamber |08 and by spring |01 reacting between stiffening member ||2 and spring retainer |24 secured to the end of screw |26. The effective force of spring |01 may be adjusted to any desired amount by screw |26, though it is generally desirable to provide only sufficient force by the spring to close orifice |00 when the engine is not running to prevent the discharge of fuel through the nozzle. After adjustment of screw |26 is made, said screw is locked in position by nut |28.

The maincontrol valve generally shown at 44 consists of a housing |28, a rotatable valve cylinder |30 having a large peripheral slot |32 and a smaller peripheral slot |34, which are adapted to establish communication between the various fuel conduits as indicated in Figures 1, 2 and 3 of the drawings. In Figure l, the large peripheral slot is shown connecting the gear pump .discharge conduit 42 with the impeller intake conduit 46 and the control pressure conduit |I8; In this,

position, thelarge peripheral slot connects the conduits required for normal engine operation while the small peripheral slot does not connect any of the conduits controlled by the valve. In

of said valve cylinder. y y operation 2.6

"l l Quasar nccts control pressure in conduit ill with the fuel .pressure in conduit |20 anterior to the gear pump'. and smaller peripheral slot I connects s' conduit 4I' posterior to the gear pump il with oo'ndl'lit Il anterior to the impeller. In 0111813081 tion. the valve permits a decrease in the pressure in and Ili on either' side of diaphragm I and consequently an increase in the lo differential acro'ssmetering'iet 24 and the flow of fuel therethrough. Valvel shifts to the left to increase the effective sise of orifice |00 to permitthe additional fuel to discharge through nosde Il. In Figure 2, the valve is in the idle cut-olf position.- the fuel pressure in conduit 42' communicating with conduit 12| anterior'to the gear pump, conduits u and m temi completely cut oil' from a source of fuel. The position of valve cylinder |30 may be controlled by lever |00 20 i ,the present metering device will deliver fuel to mounted on a shaft ioumaled in housing o f v pump 04; however. any other suitable means may be substituted for lever Ill to control the position In the normal operation of the present fuel metering device, fuel is drawn by gear pumpl Il from the source of supply through conduit l0 and discharsed under pressure into conduit' 42, the 30- 'sure in e 'Il' and-consequently the differprcssure in the latter conduit being maintained at a substantially-constant value by the spring loaded valve Il in pump bypass I0 connecting pump outlet conduit l2 with the inlet 'conduit Il.

From gear pump I0 and passage 42' the fuel 35 passes through the large peripheral slot |02 in the cylinder of three-way valve Il to impeller of centrifugal pump 2l and is discharged Iat an increased pressure into the unmetered' fuel par,

sage," from which it flows through valve controlled orifice 1l, conduit Il'. metering jet 24 and chamber Il into nozzle I1 and is discharged therefrom into the induction passage I2. With threeway'valve M in the normal operating position as shown in Figure l, fuel from passage 42' flows 45 through restriction I I0 into conduit ||0 and chamber |00 behind diaphragm |00, and, in con- Junction with spring |01, urges valve 00 toward its closed position. The pressure of the fuel in chamber |00 remains substantially equal to 'the 50 pressure in passage 42' posterior to the gear pump il, and since the latter pressure is maintained at a substantially constant value, the fluid pressure urging valve l0 to its closed position remains 'I'he pressure in outlet passage "of centrifugal pump 2l will be greater than said pump inlet pressure by an amount which is directly proporo0 tional to the square of the'speed of the pump and consequently directly proportional to the square of the' engine speed. inasmuch as the pressure` of the fuel in chamber 10 is substantially equal to the pressure in chamber |00'which is in turn' substantially the same asthe impeller inlet'pressure, the pressure of the unmetered fuel in passage Il' will be greater 'than the pressure of the metered fuel in chamber 'Il by an amount directly proportional to the square of the speed of the engine for'any slven'setting of valve 10. In the event the pressure in chamber 'Il should tend to j exceedlthe pressure in chamber |00 as a result lofmiincreased fuel flow through orifice 24, valve 90 would be urged toward its wide open position-to permutas. swaps of un addaiomrmsi mtu the induction passage. maintaining the' pre'ssure's in chalnberstllv and |00 substantially equal. A

Should the pressurein chamber l0 tend to decrease, .valve Il would be urged toward its closed position by the pressure in chamber I II. thereby permitting the pressure inv Ilv to build up to equal thatinchamber |00. f A

Inasmuch as the quantity of fuel which will flow through a given size metering orifice such as metering let A"varies in proportion t'o the square root of the' differential in pressures on l opposite sides of the orifice. and since this differential varies as the square of the engine speed, it can be seen that the quantity of fuel flowing through orifice Il fbr a given setting of valve 'l0' will vary directly as the speed of the engine.

ySince the weight of the air flow into the engine 'at a given throttle setting` varies substantially in direct proportion to the speed of the engine,

the lengine in accordance with the weight of air flowing thereinto.

When thev throttle valveis opened. the increase 'in fuel required to compensate for the increased air ilow is provided by the enlargement of the effective area of mince 14 by the withdrawal of tapered valve Il from said orifice. The increased flow of fuel through orifice il increases the presential 'across Jet I4, thus increasing the'flow' 4of .fuel through said iet into chamber10`through discharge nozzle l1 and into the induction passage '|2; however. the pressure in chamberfli l is maintained. substantially constant by the shifting of diaphragm' |00 and valve 00 away from orifice |00 to permit the'additional fuel to discharge. decreased. as when the throttle valve is '.closed, the pressure in passage I0 and `the differential in pressure across jet 2l will be reduced,I and 4as a result, the discharge of fuel through said meteringv jet is likewise reduced. The' diaphragm |06 and valve 00 will shift-toward orifice |00 and limit the discharge of fuel into `the induction pas` contour of thevalve 'l0 to sive a proportionately v constant. The total pressure urging the valve'lv closed may be modified by the adjustment of screw |20 to vary the tension on spring |01.

geater'increase in the now of fuel throughprince I4 when the throttle valve is moved either to its wide open position or toits substantially closed position. Further, certain variations can' also be accomplished by varying the 'contour of cam Il. For example, the cam ycanY be provided with a-peripheral depression at the point contacting the end of stem 00 when the throttle is moved to its wide open position, thus fully opening valve 10 and consequently increasing the pressure in passage 00' and 4the differential across metering If the effective' area, of orifice 'Il isin valve 44 during the starting period is shown v Vi in Figure 3 wherein large peripheral groove |32 is shown connecting conduits lill and lll, and? small peripheral groove il connecting the outlet 42 of the gear pump II with conduit 46 leading to the centrifugal pump. After the engine has become wann, cylinder in may be shifted to the normal operation position shown in Figure 1.

When the engine is not running, lthe discharge of fuel is prevented by shifting the position of cylinder |30 so that conduit 48 leading to the centrifugal pump is out off from the source of fuel. This is accomplished by turning cylinder |30 as shown in Figure 2 inwhich, not onlyis conduit 46 cut oi from the source of fuel, but also the inlet and outlet passages of gear pump Hare connected by the small peripheral groove |34. Conduit H8 is also out olf from both of the regulating pressures, as shown in Figure 2.

It is contemplated that' other elements or devices than those shown in the drawing may be included in the--present fuel system to obtain various desired fuel-to-air relationships under diverse engine operating conditions. The economizer for power enrichment, the acceleration device for giving temporary enrichment when the throttle is opened, and the temperature control for modifying the richness of the fuel mixture in accordance with temperature of the engine, all of which are shown and described in detail in our copending application Serial No. 607,290, filed July 27,1945, may be included in the present fuel system either separately or together, or in .any combination of the three devices, without departing from the scope of the present invention. Further, the fuel distributor and a plurality of fuel discharge nozzles such as those disclosed in our copending application Serial No. 609,230, filed August 6, 1945, may be substituted for the single nozzle arrangement shown in the present drawing. A priming means such as that shown in our copending application Serial No. 674,868, led June 6, 1946, may alsobe included to assist .in starting the engine.4

A mechanism responsive to variations in atmospheric pressurefor varying the speed of the impeller relative to the engine speed may also be included in combination with the fuel system to obtain a fuel leaning or enriching effect for maintaining proper fuel-to-air ratio under substantial variations in atmospheric pressure, such as those occurring as a. result of changes in altitude. Mechanisms for conveniently obtaining variations in the speed of the impeller relative to en gine speed are well known to those skilled in the art; for example, the impeller may be driven by the engine through a fluid drive or by variable speed pulleys.

From the foregoing description of the present invention it is apparent that a comparatively simple fuel feeding system has been developed -to give, throughout the normal operating range, a substantially constant fuel-to-air mixture ratio subject to such modification as may berequired to effect variations in said ratio for maximum economy and power and idle enrichment. Al-

though only one specific embodiment ofthe present invention has been given herein.' it will be understood that many variations in our` fuel metering device may be made without departing from the scope of our invention.

We claim:

1. A fuel supply device for an engine comprising a conduit for supplying fuel to the engine. a means for varying the pressure of the fuel in said conduit in accordancewith engine speed, a means for supplying fuel to said pressure varying means, a plurality of metering orifices in series in said conduit posterior to said pressure varying means one of which is provided with a valve for controlling the effective size thereof, a. discharge valve downstream from said orifices, and a means including a passageway communieating with said conduit anterior to said pressure varying means for controlling said discharge valve.

2. In a fuel supply system for an engine, a conduit for supplying fuel to the engine, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a means for supplying fuel to said pressure varying means at a substantially constant pressure, a plurality of metering orifices in series in said conduit posterior to said pressure varying 'means one of which is provided with a 'valve for controlling the effective size thereof, a discharge valve downstream from said orifices, a means including a either anterior or posterior to said fuel supply means.

3. In a fuel supply system for an engine, a, conduit for supplying fuel to the engine, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a plurality of metering orices in series in said conduit posterior to said pressure varying means one of which is provided with a valve for controlling the effective size thereof, a discharge valve downstream from said orifices, and a means including a passageway communicating with said conduit anterior to said pressure varying means for controlling said discharge valve. f

4. In a fuel supply system for an engine, a conduit for supplying fuel to the engine, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a plurality of metering orifices in series in said conduit posterior to said pressure varying means one of which is provided with a. manually actuated valve for controlling the effective size thereof, a discharge valve downstream from said orifices, and a'means including a passageway communicating with said conduit anterior to said pressure varying means for controlling said discharge valve.

5. v A. fuel supply device for an engine comprising a conduit for supplying fuel to the engine, a means for varying the pressure of the fuel in said conduit in accordance, with engine speed, a metering orifice in said conduit posterior to said pressure varying means provided with a manually actuated valve for controlling the effective size thereof, a discharge valve downstream from said ,orifice anda means including a. passageway com- 6. A fuel supply device for an lengine having an induction passage with a throttle valve therein comprising a conduit for supplying fuel to the engine, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a'means for supplying fuel to said pressure varying means, a plurality of metering orices in series in said conduit posterior to said pressure varying means one of which is provided with -a valve for controlling the effective size thereof, a

means operated upon movement -of said throttle -valve for actuating thevalve controlling one of speed, a means for supplying fuel to said pressure varying means, a metering orifice in said conduit.-

posterior to said pressure varying means provided with a valve for controlling the effective size thereof, a means operated by the movement of said throttle valve for actuating the valve controlling said metering orifice, a discharge valve downstream from said orifice, anda means including a passageway communicating with said conduit anterior to said pressure varying means b for controlling said discharge valve.

8. In a fuel supply system for an engine having .an induction passage with a throttle valve therein, a fuel conduit, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a plurality of metering ori- Iiices in series in said conduit posterior to said pressure varying means one of which is provided with a valve for controlling the effective size thereof, a means operated upon movement of said throttle valve for actuating the valvecontrolling one of the metering orifices, a discharge valve downstream from said orifices, and a means including a passageway communicating with said conduit anterior to said pressure varying means for controlling said discharge valve.

9. In a fuel supply system for an engine having an induction passage with av throttle valve therein, a conduit for supplying fuel to the engine, a means for varyingthe pressure of the fuel in said conduit in accordance with engine speed, a metering orifice in said conduit posterior to said pressure varying means provided with a valve for controlling the effective size thereof, a means operated upon movement of said throttle valve for actuating the valve controlling said metering orifice, a discharge valve downstream from said orice, and a means including a passa'geway communicating with said conduit anterior to said pressure varying means for controlling said discharge valve.

10. In a fuel supply system for an engine having an induction passage with a throttle valve therein, a conduit for supplying fuel to the engine, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a means for supplying fuel to said pres-V sure varying means, a plurality of metering orifices in series in said conduit posterior to said pressure varying means one of which is provided with a valve for controlling the effective size thereof, a means operated upon movement of said throttle valve for actuating the valve controlling one of said metering orifices, a discharge including a passageway communicating with said conduit anterior to vsaid pressure varying means for controlling said discharge valve, and a control valve for connecting said passageway with the conduit either anterior or vposterior to said fuel supply means.

11. In a fuel supply system for an engine having an induction passage with a throttle valve therein, a conduit for supplying fuel to the engine, a means for varying the pressure of the fuel in said conduit in accordance withengine speed, a means for supplying fuel to said pressure varying means, va metering orifice in said conduit posterior to said pressure varying means provided with a valve for controlling the effective size thereof, a means operated upon movement of said throttle valve for actuating the valve controlling said metering oriiice, a discharge valve downstream from said orifice, a means including a passageway communicating with said conduit anterior to said pressure varying means for'controlling said discharge valve, and a control valve for connecting said passageway with the conduit either anterior or posterior to said fuel supply means.

12. A fuel supply system for an engine having an induction passage with a throttle valve therein comprising a conduit having a discharge nozzle in said induction passage for supplying fuel to the engine, a means for varying the pressure passageway communicating with said conduit anterior to said pressure varying means for controlling said discharge valve.

13. A fuel supply device for an engine having an induction passage with a throttle valve thereincomprising a conduit for supplying fuel to thev engine, .a means for varying the pressure of the fuel in said conduit in an amount substantially proportional'to the square of the engine speed,

a means for supplying fuel to said pressure varying means, at least one metering orice in said conduit posterior to said pressure varying means, a valve for controlling the now of fuel through a metering orifice, a means operated upon movement of said throttle valve for actuating said orice control valve, a nozzle including a valve for discharging fuel from said conduit into said induction passage, a means including a passageway communicating with said conduit anterior to said pressure varying means for controlling said discharge nozzle valve, and a control valve for connecting said passageway with the conduit either anterior or posterior to said fuelv supply means.

14. In a fuel supply system for an engine having an induction passage with a throttle valve therein, a means f or varying the pressure of the fuel in said conduit in accordance with engine speed, at least one metering orice in said conduit posterior to said pressure varying means, a valve for controlling the iiow of fuel through a metering orifice, a means operated upon movement of said throttle valve for actuating said metering orifice control valve, a nozzle includ- 'said induction passage, at least one metering restriction insaid conduit, a nozzle including a valve controlled by a pressure regulated member for discharging the fuel from said conduit into said induction passage, a conduit communicating with the inlet side of said centrifugal pump and with said pressure regulated member for regulating the discharge of fuel from said nozzle, and a valve for varying the effective size of a metering restriction upon variations in load resulting from variations in throttle position.

16. In a fuel system for an internal combustion engine having an induction passage with a throttle valve therein, a conduit for supplying fuel to said engine, a fuel supply pump in said conduit, a valve controlled pump by-pass around said pump for maintaining a substantially constant fuel delivery pressure, a. centrifugal pump in said conduit for receiving -fuel delivered by said supply pump and for discharging it at an increased pressure, a plurality of metering orices for controlling the iiow of fuel through a meter'- ing orifice, a mechanism for actuating said metering orifice control valve, a nozzle including a valve for discharging fuel from said conduit into said induction passage, and a means including a passageway communicating with said conduit anterior to said pressure varying means for controlling said discharge valve.

18. In a fuel supply system for an engine having an induction passage with a throttle valve therein, a pump for varying the pressure of the fuel in said conduit in accordance with engine speed, a second pump for supplying fuel to said first mentioned pump, at least one metering oriflce in the conduit posterior to `said pumps, a

' valve for controlling the iiow of fuel through a metering orifice, a mechanism for actuating said metering orifice control valve, a nozzle including a valve for discharging fuel from said conduit into said induction passage, and a means including a passageway communicating with said conduit anterior to said rst mentioned pump for controlling said discharge valve.

19. In a fuel supply system for an engine having an induction passage with a throttle therein, a conduit for supplying fuel to the engine, a

vmeans for varying the pressure of the fuel in said conduit in accordance with engine speed, a metering orice in said conduit posterior to said pressure varying means, a valve for controlling,

the effective size ofA said metering orifice, a linkin series in said conduit posterior to said centriugal pump one of which is provided with a valve for controlling the eective size thereof, means operated by the movement of said throttle valve for actuating the valve controlling one of the metering orifices, a discharge valve downstream from said metering orifices, aV control member including a passageway communicating with said conduit anterior to said centrifugal pump, and a control valve for connecting said passageway with the conduit either anterior to said supply pump or between said supply pump and said centrifugal pump.

17. In a fuel system for an engine having an induction passage with a throttle valve therein, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, at least one metering orifice in said conduit posl terior to said pressure varying means, a valve age connecting the metering orifice valve with the throttle actuating mechanism for operating Asaid valve in accordance with throttle position,

and a discharge valve in the conduit downstream from said orifice for regulating the metered fuel pressure.

EMIL O. WIRTH. FREDERIK BARFOD.

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

UNITED STATES 'PATENTS Mock Aug. 19, 1947