US2397984A

US2397984A - Fuel metering means

Info

Publication number: US2397984A
Application number: US541009A
Authority: US
Inventors: Carl F Schorn
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-06-19
Filing date: 1944-06-19
Publication date: 1946-04-09
Anticipated expiration: 1963-04-09

Description

April 1945- c. F. SCHORN FUEL METERING MEANS Filed June 19, 1944 3 Sheets-Sheet 1 all '1'? AS25019:

IN VENT OR.

Filed June 19, 1944 3 Sheets-Sheet 2 Liv-2 Eamon:

INVENTOR.

HTTOE/VEY Patented Apr. 9,1946

FUEL METERING MEANS Carl F. Schorn, Detroit, Mich., asslgnor to George M. Holley and Earl Holley Application June 19, 1944, Serial No. 541,009

27 Claims.

The object of this invention is to regulate the ratio of fuel to air in an internal combustion engine.

Figure 1 shows diagrammatically the elements of my invention in its simplest form.

Figure 2 shows diagrammatically the elements of the preferred form of my invention.

Figure 3 is an enlarged view of the left-hand portion of Figure 2.

In Figure 1, I is the fuel entrance and II is the fuel outlet. I2 is a shaft which is driven at engine speed or a fraction thereof. I3 is the main fuel pump which supplies fuel to the engine. I4 is an auxiliary or recirculating positive displacement fuel pump which creates pressures in proportion to the square of the engine revolutions per minute and thus forms part of the control mechanism for regulating the fuel flow. I5 is a connection which admits the intake manifold pressure from the engine side of a supercharger I58 and communicates through pipe I58 to discharge into a chamber 49 which contains a flexible metal capsule assembly. This capsule assembly is divided into two sections sealed one from the other. The lower section I8 is partially evacuated while the upper section II is communicated to engine exhaust pressure by means of connection I6.

Valve I9 is the fuel measuring device connected to the capsule assembly and is located in a fuel passage 28 and controls the fuel flow from passage 20 to a fuel outlet passage 2I. The valve I3 is supported by a, spring 22. The passage through the center of valve I8 permits the pressure in chamber 48 to be applied to the lower end of the valve.

The positive displacement pump I4 creates a pressure differential across the restriction between the oriflce 23 and the needle 25, which pressure drop varies directly with the square of the revolutions per minute of the engine by circulating fuel from fuel entrance I!) through pump I4 to chamber 24 past restriction 23-45 back into the fuel inlet III. The movable needle 25 is responsive to a temperature device 26, which is located adjacent to the air intake I58 of the engine and is provided to control the area of the restriction 23. The temperature device is located within a chamber I10 and an opening Ill causes circulation of air through this chamber and out through the opening I12 adjacent to the throttle I51.

A diaphragm 21 responds to the pressure differential across the restriction 23-25 since the chamber 28 located to the right of diaphragm 21 is connected through the passage 28 to the fuel inlet pressure.

The chamber 3I to the right of diaphragm 30 is communicated through passage 41 to the fuel in passage 20, therefore, the 'drop in pressure across the diaphragm 30 is the same as the drop across the metering valve I8. Diaphragms 21 and 30 are connected-to each other by means of the shaft 32., Connected to the diaphragm 30 is the balanced pressure control valve 33. When the engine speed causesan increase in the pressure drop across diaphragm 21, the shaft 32 and diaphragm 30 moves to the right and valve 33 moves to the left to increase the fuel discharge opening from chamber 2| to outlet passage 34. This causes an increase in the pressure drop across the valve I9 and thus across the diaphragm 30.

Fuel in passage 34 raises the diaphragm 35 and fuel discharges to the engine through outlet II. Diaphragm 35 is loaded with the spring 38 and the inlet fuel pressure which is supplied through passage 31. There is then maintained an adequate pressure in the pipe I I.

A fuel venturi 38 in the passage leading to the valve I8 creates a pressure difference which responds to the flow of fuel. The pressure of the fuel entering the venturi 38 is applied tothe upper side of the diaphragm 39 and the decreased pressure in the throat of the venturi 38 is applied to the lower side of a diaphragm 39 through the passage 40. Diaphragm 39 is supported by spring H and supports the tapered needle 42, which controls the supply of the extra fuel needed for high power, especially in an air-cooled engine where extra fuel is required to prevent the engine from overheating.

A relief valve 43 loaded with a spring 44 and connected through a passage 45 with the passage 34 is provided so that when the pressure generated by the main fuel pump I3 exceeds a set value above the pressure in discharge passage, the fuel flows back and is recirculated into the fuel inlet III. This puts a ceiling on the pressure drop through the metering system. By controlling the maximum pressure drop that can occur through the metering system, the droop in the air flow curve at high engine speeds can be compensated for. A manual mixture control valve 46 introduces a restriction 48 across the recirculating pump I4 so that when this valve is moved from the full rich position marked FR to the cruising lean position marked CL, valve 48 increases the area of the restricted passage leading from the high pressure side of the pump I4 back to the entrance II). This means that at a given speed there is less l, pressure drop across the diaphragm 21 and therefore less pressure acting on the rod 32, and, therefore, less pressure drop across diaphragm 30 and valve I9, thus less fuel is discharged at II. When the valve 48 is moved into the position marked SO, which means shut off, there is a wide-open short circuit across the pump I4, and the pressure drop across the metering valve I9 drops to substantially zero and no fuel flows.

Operation of Figure 1 valve I9 at any given opening will square root of the drop across the valve. Therefore, the flow varies directly with engine speed. The size of the opening past valve I9 is controlled by the intake manifold pressure in chamber 49. Therefore, the flow into the engine varies with engine speed and manifold air pressure.

As the plane ascends, the pressure in capsule I1 falls and thereby causes a relative decrease in the capsule height at a given manifold air pressure. This causes the valve I9 to further move to increase the opening between passages 20 and 2| and, therefore, the fuel flow to the engine is increased. The increase in flow compensates for the increase in air flow into the engine (at any given engine speed and manifold pressure) caused by the decrease in pressure on the exhaust side of the engine. An increase in intake manifold temperature causes an increase in the size of the opening through restriction 23 and, thereby, the

- metering head across valve I9 is reduced for any given speed. This change in metering head compensates for the temperature variations in manifold temperature reducing the fuel flow as the temperature increases.

With-increased engine speed and manifold pressure, the increase in the fuel flow through the fuel venturi 38 causes the pressure drop across diaphragm 39 to increase until the weight of the spring H is overcome and additional fuel passes valve 42 and is admitted to the engine.

To operate at better economy, the valve 46 is manually rotated clockwise into the cruise lean CL position and the drop across the restriction 23 is lowered because of the added fuel capacity of the restriction 48. This causes a lower metering head across the metering valve I9 and therefore a decreased fuel flow at any given engine speed.

The device shown has been divorced from the air control means of the engine and its operation is quite independent of the air flow and of the density of the air entering the engine, being controlled simply by the revolutions per minute, the temperature of the air entering the engine cylinders and the intake manifold pressure, which are the controlling factors in determining its desired fuel supply.

However, to make the disclosure complete, an air entrance I56 is shown with a throttle I51, a supercharger housing I58, communicating with the inlet manifold. The temperature responsive element is shown located in a chamber I conthat is, in full rich position, fuel given temperature) as the a square of the engine speed. The flow past the vary as the nected by a passage I12 with the engine side of the throttle I51 and through opening "I with the manifold air pressure. The element 25 is thus held at the temperature of the manifold. The fuel outlet II is shown discharging into the center of the supercharger housing I53.

Description of Figure 2 fraction thereof, 53 is a fuel pump supplying fuel to the engine, 54 is an auxiliary pump having a constant delivery per revolution; both pumps are driven by the shaft 52.

'89 is a chamber connected through a passage 3 55 to the supercharger I59 of the engine through the pipe I59. (See Figure 1.) 55 is a connection for admitting atmospheric pressure to act on the left-hand side of a piston 51,- the right-hand side of the piston 51. communicates with the chamber 89 through a, restriction 98. The right-hand side of the piston 51 also communicates with the air entrance through a restriction I00. The difference of the pressures acting on the two opposite sides of the piston 51 is therefore somewhat less than the difference between atmospheric pressure and the pressure in the chamber 89, which is the pressure of the supercharger, and by changing the restriction I00, this difference is regulated.

58 is a group of three evacuated capsules located in the chamber 99 and secured to the left-hand wall thereof, and this group thus responds to the pressure difference between the manifold air pressure and whatever pressure remains in the exhausted capsules 58. 99 is a servo valve connected to and moved by the capsules 58 and by the piston 51. The valve 99 controls the admission of high pressure fuel from a passage connected to the high pressure side of the pump 53 to a passage 9|, which applies this high pressure to a chamber 91. This chamber 91 has a moving wall consisting of a diaphragm 93. Hence, the

high pressure acting through the passage 90 pushes the diaphragm 93 to the right. The chamber 94 located on the right-hand side of the diaphragm 93 communicates through the pipe 95 connected to the fuel entrance 50, that is to the low pressure.

A passage 95, which is also connected to the low pressure pipe 95 and is also controlled by the valve 99 permits high pressure fuel to escape from the chamber '91 located on the left-hand side of diaphragm 93 when the valve 99 moves to the right. Hence, the pressure difference between that in the chamber 91 on the left-hand side of diaphragm 93 and the pressure in chamber 94 balances the differential between the capsule sealing pressure and the manifold air pressure acting on the effective area of capsules 58, plus or minus the effect of the atmospheric and manifold air pressure differential acting on the piston 51. Pressure in the chamber 91 is thus caused to vary with the manifold air pressure and is modified slightly by the atmospheric pressure. The pressure in 91 is transmitted through a passage I03 in the valve 59 to a chamber I05 located above a horizontal diaphragm I0 I This diaphragm IOI thus responds to the high pressure transmitted through passage I03 and compresses the compression spring 62 and moves the valve 59. A balance spring I02 is provided to keep the diaphragm IOI in equilibrium when the pressure differential across diaphragm IOI equals zero. The low pressure pipe 95 communicates with the chamber I06 below the diaphragm IOI; therefore, the pressure diflerential across diaphragm IN is the same as the pressure differential across diaphragm 33. The valve 59 thus responds to variations in the absolute value of the air pressure in the engine manifold and in the difference between the pressure of the atmosphere and the manifold air pressure.

The flow of fuel past the valve 59 is made to respond to the revolutions per minute of the en-. gine by the following means: the positive displacement pump 64 creates a pressure difference between the inlet and the outlet, which will vary with the engine speed by circulating fluid first through the small restriction I11 and then (when sufllcient pressure exists to unseat valve I15 against the load of spring 116) also through a restriction 63. The fuel flows in a circuit from the fuel entrance 50 through pump 54 through restrictions I and through a restriction 63 to the fuel inlet 50. The purpose of spring loaded valve I and restriction I" is to alter the relationship between the pressure drop across restriction 63 and engine speed to satisfy the empirical formula:

I Basic engine fuel flow= w An internal combustion engine might be considered as a suction pump. During the intake stroke, the piston draws a mixture of air and fuel into the cylinders. The total volume of air and fuel drawn into the engine in any given time interval depends upon the number and size of the cylinders an engine has (displacement) and the crankshaft speed. In a four-cycle engine, since there is one suction stroke for each two crankshaft revolutions, the revolutions per minute of the engine is divided by two. Since we are concerned with the weight of air and fuel entering the engine and not volume, the density of the mixture must be considered. 3

Assume for the moment that air alone is being drawn into the engine, from the law of gases we have:

PV= MBT PV -B-T where M=weight of air in lbs.

I P=pressure of the air in lbs. per sq. foot.

B=air constant-53.34 approximately =absolute temperature-degrees Fahrenheit V=volume in cu. feet displaced 1 For anengine, the formula may be written L=iength of stroke in feet A=area of piston in sq. feet N=revolutions per minute where M =weight of air entering the engine per unit of time 22;]. the displacement of the engine per unit of time read where M. A. P. equals manifold air pressure in 7 pounds per square inch absolute.

The value of the constants in the above empirical formula may be determined from engine test data.

Since the basic fuel air mixture entering an engine is held at substantially a fixed ratio, therefore, the same factor that governs the air flow into the engine may be used to govern the basic fuel flow. We may therefore write a formula for the basic fuel flow into the engine as follows:

The constant K includes the mixture ratio factor. In actual practice, K will determine the design and shape of the metering orifice of the metering system disclosed in my application.

Since the backpressures on the exhaust system of an engine used on aircraft varies for each alti tude and thereby affects the power output of the engine, it is necessary to medify the value of C for each altitude. This is accomplished in my disclosure by the use of the piston 51, Figure A movable restricting needle 65 is provided responsive to a temperature device 66, which corrects for the temperature variation of the air entering the engine cylinders. (See Figure 1.) The temperature device 66 may be located in the inlet manifold adjacent to the inlet valves.

The adjustment of the location .of the restriction 63 is obtained by the action of diaphragm I40, which is pushed to the left by the spring I and the pressure in chamber! and is pushed to the right by the pressure in chamber I43. The travel is limited by the adjustable screw and nut I 41 and I48. With the manual valve I45 in the position shown, low pressure fuel is admitted to chamber I42 to the right of diaphragm I40 through the passages I44 and I64 controlled by the valve I45. Under this condition, the relatively low pressure in chamber I42 causes the high pressure in chamber I43 to move the diaphragm to the right, against the pressure of spring 4|. When valve I45 is rotated 120 anticlockwise, it places the passage 10 in communication with the chamber I42 through the passages I60, I64 and I65. The compression spring HI and the increased pressure in chamber I42 then overcomes the pressure in chamber I43 and the nut I48 engages with the stop I49 and the diaphragm I40 moves to the left carrying with it the restriction 63. when the flow through the venturi I8 exceeds a predetermined maximum, the spring I 4| is again compressed and the lean mixture is restored.

The restriction 63 is carried by a perforated tube which is carried by two diaphragms IN and I62. The fuel under pressure from the pump 54 acts against both diaphragms I6I and I62 so that this pressure is balanced and has negligible effect on the location of the restriction 63. I I

A rod carried by the diaphragm I 40 acts as a stop when the diaphragm I40 mov es to the right and the rod engages with the adjustable stop I41.

In the upper right hand portion of Figure 2 is shown the device which increases the fuel flow with increasing revolutions per minute. A diaphragm 51 forms the left-hand side of a chamber I24; this chamber is connected through pipe 84 to the pressure side of the recirculatinz'pump 54. The chamber 88 to the left of diaphragm 81 communicates with the low pressure. side of the system through pipe 95. Therefore, the pressure differential across diaphragm 81 varies as a function of engine speed as modified by the poppet valve I15, spring I15 and restriction I11.

The diaphragm I 50, which is connected through the rod 12 with the diaphragm 51, is subjected on its right-hand side to the pressure of the fuel as it leaves the fuel valve 59, the pipe connecting the chamber 1' with the downstream side of valve 59. The chamber H to the left of diaphragm I50 communicates through the pipe 81 with the left-hand side of the valve 58; that is to say, to the high pressure side of this valve. Rod 12 connects the two diaphragms together.

Hence, the pressure differential acting on the diaphragm 51 is balanced against the fuel pressure drop across the valve 59 acting on the diaphragm I50. Diaphragm I50 is lever connected to the valve 13, which, when the revolutions per minute increase, opens and increases the fuel flow from chamber H1 and hence the pressure drop across the valve 59 acting on thediaphragm I50 increases; hence, the valve 13 opens so as to deliver fuel to the outlet passage 14'at such a rate as to create a pressure difference on the diaphragm I50, so as to balance the pressure difference acting on the diaphragm 81. Y

The fuel flowing through 14 passes the valve 2", the purpose of which is to maintain a deflnite pressure in the outlet passa'ge I28. The valve 2" is moved by the diaphragm I08, which is loaded by the spring I09. The chamber to the left of diaphragm I08 communicates with the low-pressure side of the system through restriction I23. The pressure to the right of diaphragm will be maintained at the pressure necessary to balance the fuel pressure to the left of diaphragm I08 plus the pressure required to balance the load of spring I09.

The shut-off valve H5 and the by-pass IIG short circuit the diaphragm I08 when the valve I I5 is rotated 90". When this happens, the pressure is substantially equal on both sides of the diaphragm I08 and the valve 2I1 closes under the pressure of spring I 09 and the flow of fuel is shut off.

Fuel flowing through venturi 18 creates a pressure drop at the throat of the venturi, which is responsive to the rate of flow. This throat pressure is communicated by the line 10 to the chamber to the left of diaphragm I35. The pipe I I4 communicates with the right-hand side of the diaphragm I35. The pressure difference acting on the diaphragm I35 opens a valve 82, which admits fuel to the passage I25. This fuel flows past the shut-off valve I25 on its way to the passage I21, which communicates with the fuel outlet passage I28.

Alternatively, when valve I5I is rotated 90,

water is admitted at the entrance passage I29 through the valve I5I. This water enters under a pressure substantially equal to the fuel pressure from discharge side of pump 53, the water pressure is applied to the right-hand side of diaphragm I52 and thus moves the shut-off valve I25 to the'left, which shuts off the fuel flowin through I25, (the valve I28 is mounted on the diaphragm I52). Water then flows through a the passage a ount of water as the pressure difference between the pipe 10 and the pipe II4 varies with the'fuel flow through the venturi 18. This water then flows through the pipe I21 to the passage I28.

At low speed the pressure in passage on the discharge side of pump 54 acts on another diaphragm II9. This pressure is communicated through the pipe I14. The spring I is located on the left-hand side of the diaphragm H9 and tends to open the valve I I8. Chamber I22 to the left of the diaphragm II9 communicates with the low pressure fuel pipe 95 through the restriction I23 and through chamber H0. The valve II8 thus controls the flow of fuel for idle speed supplied from a passage I32 which communicates with the chamber I83 which in its turn communicates with the high-pressure fuel pipe II4. By this means, during the lower revolutions per minute, when the pressure differential across diaphragm I I9 is smalLthe valve H8 is opened to supply the fuel for idle. As the engine speed picks up and the pressure drop across pump 54 and, therefore, across diaphragm II9 increases thefue'i flow past valve II 8 is decreased and is finally stopped.

The pressure relief valve 83 is shown in lower left hand portion of Fig. 2 and is operated by means of a diaphragm 85 and a compression spring 84. The right-hand side of the diaphragm 85 is subjected to the high pressure in the fuel line II4 through a. passage I55. when the pressure in the discharge side of pump 58 exceeds the designed limit above the inlet fuel pressure, then valve 83 is unseated against a spring 84, whichspring normally holds the valve 83 seated.

Operation of Figures 2 and 3 fore, high pressure fuel from the main fuel de-' livery pump 53 flows through passage II4, through the chamber I33 to the right of diaphragm I35, through passage I32, past valve II8 I into the discharge fuel passage I 28. Suihcient pressure builds up in passage I28 to overcome the fuel pressure to the left of diaphragm I08 and the weight of spring I09 so that the idle fuel flows past the valve, 2".

As the engine speed is increased, the increase in pressure differential across fuel pump 54 causes the idle valve II8 to close. Meanwhile, the pressure differential causes the poppet valve I15 to leave its seat and thereby fuelg'is caused to flow past restriction 53. The pressure differential across restriction 53 acts on diaphragm 51. The force acting on diaphragm 51 is balanced by the force acting on diaphragm I50, which diaphragm adjusts the fuel outlet valve 13 to regulate this differential. The drop across main fuel metering valve 59 is identical to the drop across diaphragm I50, and this drop constitutes the basic fuel metering head for the metering system. Manifold air pressure is transmitted from the supercharger housing into chamber 89, which contains a partially-evacuated element 58 and the right side of piston 51, the expansion and contraction of element 58 plus the pressure drop across piston 51 moves the valve 99 to the left or right of the port entering the I30 past the valve I8I, which regulates passage 9|. When the pressure in chamber 89 increases, the valve 99 tends to move to the left to admit high pressure fuel into passage 9| to the left of diaphragm as. Sufficient fuel is admitted to create a pressure differential across diaphragmaflto return the valve 99 to its neutral position. ?The right side of the diaphragm 99 is communicated with the low-pressure side ofthe system;I'hepressureidrop across diaphragm 93 thus varies withthe manifold air pressure in 10 chamber 89 and to the right of piston 51. The

pressure in 91 is transmitted through the passage I83 in the center of the valve 59. The pressure in the chamber I85 is thus equal to the pressure in the chamber 91. The chamber I98 is also communicated to the low-pressure side of the system; therefore, the pressure drop across diaphragm III I is equal to the pressure drop across diaphragm 93 and thus also varies with manifold air pressure. 'The load on diaphragm el-81,120

acting against the force of the balancing springs I82 and 62, position the metering valve 59. An increase in manifold air pressure cause? an increase in the metering passage past valve 59.

The basic flow through the metering system varies with the size of the metering passage controlled by downward movement of the valve 59 and with the square root of the metering head across the valve 59, which metering head is created by the speed of the engine. The high pres- 90 At these high basic fuel flows, water may be substituted for the additional fuel flow past valve 82 by opening the water supply valve I5I. This causes the valve I25 to move to the left to close passage I25. Meanwhile, wa-

ter is admitted past valve I3I into the discharge 5 passage I28, past the valve 2I'I into the engine. To compensate for changing temperature of the mixture entering the engine cylinders, the

temperature-responsive device 66, which islocated in the engine intake manifold, moves the needle 65 to the right with increasing mixture temperatures. This causes an increase in the size of the restricted fuel passage and thereby reduces the drop across the fuel metering valve 59.

mixtures in the cruising range of the engine, the manually controlled valve I45 is rotated 120 anticlockwise; this places the right side of the diaphragm I40 in communication with the throat of the fuel venturi I8. Therefore, the pressure drop across the diaphragm I40 is equal to the pressure drop in the throat of the fuel venturi 18. At low fuel flows corresponding to the cruising range of the engine, the pressure drop is insuflicient to overcome the load of the spring MI and, therefore, the restriction 63 is moved to the left to increase the size of the restricted opening in the recirculating pump system and,

therefore, the metering head across the fuel me- 7 tering valve 59 is reduced and the fuel flow is decreased.

As the fuel flow through the fuel venturi I8 increases beyond the flow corresponding to engine power at which best economy mixtures are 7 55 When it is desired to operate at best economy safe, the pressure drop across the diaphragm I48 becomes sufficient to overcome the weight of. the spring I and thereby the restriction 99 is moved to the right to enrichen the carburetor mixture.

Relief valve 83 acts to maintain the discharge pressure of pump 58 at a constant value above the pressure of the fuel entering the device. Shouldthe pressure rise through pump 59 and exceed that determined by the force of spring 84, the valve unseats andpermits fuel to be by-passed to the inlet side of the system.

As the plane ascends, the decrease in atmospheric pressure causes a relative increase in the pressure drop across the piston 51. This has a direct effect on the servo valve 99 and, therefore, upon the diaphragm 98 and upon diaphragm IIII which opens fuelmetering valve 59 as an increase in manifold mixture pressure occurs.

The carburetor, therefore, enrichens the mixrture with an increase fin altitude to compensate -for the increasein engine power due to a decrease 'in the back pressureon the engine.

To shut the fuel system oil; mineral valve I I5 is rotated 1. A fuel metering device for an internal combustion engine having a supercharger, comprising a source of fuel under pressure, a fuel passage, a fuel measuring valve therein, a restricted passage, an engine-driven pump adapted to displace fuel in proportion to the engine revolutions per minute and connected to said restricted passage so as to pump fuel through said restricted passage, a moving wall, two chambers located one on each side of said wall, one chamber being connected to the high pressure side of the said pump and on the other being connected to the low pressure side of said pump, a second moving wall connected with the first moving wall, two chambers located one on each side of said second wall, one of said last mentioned chambers being connected to the pressure on the upstream side of the fuel measuring valve and the other chamber located on the other side thereof being connected to the downstream side of the fuel measuring valve, a second valve located in the fuel passage downstream from the fuel measuring valve and adapted to be opened and closed by the movement of said moving walls so as to control the pressure difference across said measuring valve, to balance the pressure created by said pump, a fuel outlet for said second valve, means responsive to the supercharger pressure for opening and closing said fuel measuring valve.

2. A device as set forth in claim 1, in which there is a second fuel passage and a second fuel measuring valve located in parallel with the first fuel measuring valve and first fuel passage, means responsive to the rate of fuel flow through said first fuel passage and first measuring valve for opening said second fuel measuring valve when the flow through the first passage exceeds a predetermined value.

3. A device as set forth in claim 1, in which there is an idling fuel passage and measuring valve located in parallel with the first fuel easuring valve and adapted to supply the fuel This places the right side of" diaphragm I08 in communication with the "left required for idling, means responsive to the engine-driven pump for closing said idling fuel measuring valve as the engine speed is increased above the idle speed.

4. A device as set forth in claim 1 in which there is a water entrance, a, water passage connecting said entrance to the fuel outlet, an automatic valve in said water passage controlling the water flow, means responsive to the rate of fuel flow through said fuel passage past said fuel measuring valve for opening said water' valve.

5. A device as set forth in claim 1, in which there is a second fuel passage andtas-se'cond fuel measuring valve means located in parallel with the first fuel measuring valve and first fuel passage, means responsive to the rate offuel flow through said. first passage and iirst fuel'measuring valve for opening said secondfuel measuring valve when the flow through the first fuel measuring valve and passage exceeds a predetermined value, a water entrance, a water passage connecting with said fuel outlet and in parallel with said first fuel measuring valve, means responsive to the rate of fuel flow through said first fuel measuring valve and passage to admit water to the fuel outlet, means responsive to the pressure of the water for restricting the fuel flow through said second fuel measuring valve.

6. A device as set forth in claim 1, in which there is a temperature responsive means to modify the action of said pump, whereby at high tem peratures, the pressure generated by the enginedriven pump for any given revolutions per minute will be lower than at low temperature.

7. A device as set forth in claim 1 in which the means responsive to the supercharger pressure is modified by means responsive to the difference between the supercharger pressure and the pressure of the atmosphere.

8. A device as set forth in claim 1 in which the means responsive to the supercharger pressure for opening and closing the fuel measuring valve comprises a servomotor, a servomotor valve associated therewith, a chamber connected to said supercharger, an evacuated capsule in said chamber connected to said servomotor valve, said servomotor being connected to said measurin valve and the source of fuel under pressure being the motive force for said servomotor,

9. A device as set forth in claim-1, in which the means responsive to the supercharger pressure for opening and closing the fuel measuring valve comprises a servomotor, a servomotor valve associated therewith, a, chamber connected to said supercharger, an evacuated capsule in said chamber, an additional chamber, a moving wall in said last mentioned chamber dividing it into two halves, a connection from one half to the atmosphere, the other half being in restricted communication with the supercharger, a restricted outlet from said chamber to the atmosphere, said servomotor valve being connected to said moving wall and to said capsule, said servomotor being connected to said measuring valve, and the source of fuel under pressure being the motive force for said servomotor.

10. A device as set forth in claim 1 in which the pump adapted to displace fuel in proportion to the revolutions per minute isprovidedwith a variable restriction formed between two elements consisting of a movable needle and of a movable restriction, temperature responsive means for moving one element, a manually operated means for moving the other element into one of two positions so that there is a power mixture range and a cruising lean range manually selectable but which at the same time is subject to control by the temperature responsive means.

11. A device as set forth in claim 1 in which there is a spring loaded poppet valve adapted to modify the relationship between the pressure differential across the restricted passage and the fuel flow through the pump in response to the speed of the engine.

12. A device as set forth in claim 1 in which there is a second fuel pump adapted to create the source of fuel under pressure whereby the fuel pressure is maintained at the inlet to said fuel measuring valve.

13. A device as set forth in claim 1 in which the pump adapted to displace fuel in proportion to the revolutions per minute of the engine is provided with a variable restriction, the flow through which creates a pressure drop across the said restriction, and manually operated means for selecting the maximum and minimum areas of said variable restriction.

14. A device as set forth in claim 1 in which the pump adapted to displace fuel in proportion to the revolutions per minute is provided with a variable restriction, the flow through which creates a pressure drop across said restriction, manually operated means for selecting the maximum and minimum areas of said variable restriction, and means responsive to the flow of fuel past said fuel measuring valve for automatically restoring the variable restriction to its minimum position whenever the flow exceeds a predetermined value to prevent the operation at high power output with minimum fuel air ratios. 7

15. A fuel metering device for an internal combustion engine having a supercharger comprising an engine driven fuel pump adapted to raise the pressure of fuel, a fuel passage leading therefrom, a fuel measuring valve therein in free communication with said fuel pump, a restricted passage, a second engine driven pump adapted to displace fuel in proportion to the engine revolutions per minute and connected to said restricted passage so as to pump fuel through said restricted passage, a moving wall, two chambers located one on each side of said wall, one chamber being connected to the high pressure side of the said second pump and on theother being connected to the low pressure side of said second pump, a second moving wall connected with the first moving wall, two chambers located one on each side of said second wall, one of said last mentioned chambers being connected to the pressure on the upstream side of the fuel measuring valve and the other chamber located on the other side thereof being connected to the downstream side of the fuel measuring valve, a second valve located in the fuel passage downstream from the fuel measuring valve and adapted to be opened and closed by the movement of said moving walls so as to control the pressure difference across said measurin valve, to balance the pressure created by said second pump, a. fuel outlet for said second valve, and means responsive to the supercharger pressure for opening and closing said fuel measuring valve.

16. A fuel metering device for an internal combustion engine having an inlet manifold, comprising a source of fuel under pressure, a fuel passage, a fuel measuring valve therein, a restricted passage, an engine-driven pump adapted to displace fuel in proportion to the engine revolutions per minute and connected to said restricted passage so as to pump fuel through said restricted passage, a moving wall, two chambers located one on each side of said wall, one chamber being connected to the high pressure side of the said pump and on the other being connected to the low pressure side of said pump, a second moving wall connected with the first moving wall, two chambers located one on each side of said second wall, one of said last mentioned chambers being connected to the pressure on the upstream side of the fuel measuring valve and the other chamber located on the other side thereof being connected to the downstream side of the fuel measuring valve, a second valve located in the fuel passage downstream from the fuel measuring valve and adapted to be opened and closed by the movement of said moving walls so as to control the pressure difference across said measuring valve, to balance the pressure created by said pump, a fuel outlet for said second valve, means responsive to the manifold air pressure for opening and closing said fuel measuring valve.

17. A device as set forth in claim 16 in which there is a second fuel passage and a second fuel measuring valve located in parallel with the first fuel measuring valve and first fuel passage, means responsive to the rate of fuel flow through said first fuel passage and first measuring valve for opening said second fuel measuring valve when the flow through the first passage exceeds a predetermined value.

18. A device as set forth in claim 16 in which there is an idling fuel passage and measuring valve located in parallel with the first fuel measuring valve and adapted to suppl the fuel required for idling, means responsive to the enginedriven pump for closing said idling fuel measuring valve as the engine speed is increased above the idle speed.

19. A device as set forth in claim 16 in which there is a water entrance. a water passage connecting said entrance to the fuel outlet, an automatic valve in said water passage controlling the water flow, means responsive to the rate of fuel flow through said fuel passage past said fuel measuring valve for opening said water valve.

20. A device as set forth in claim 16 in which there is a second fuel passage and a second fuel measuring valve means located in parallel with the first fuel measuring valve andfirst fuel passage, means responsive to the rate of fuel flow through said first passage and first fuel measuring valve for opening said second fuel measuring valve when the flow through the first fuel measuring valve and passage exceeds a predetermined value. a water entrance, a water passage connecting with said fuel outlet and in parallel with said first fuel measuring valve, means responsive to the rate of fuel flow through said first fuel measuring valve and passage to admit water to the fuel outlet, means responsive to the pressure of the water for restricting the fuel fiow through said second fuel measuring valve.

21. A device as set forth in claim 16, in which there is a temperature responsive means to modify the action of said pump, whereby at high temperatures, the pressure generated by the engine driven pump for any given revolutions per minute will be lower than at low temperature.

22. A device as set forth in claim 16 in which 7 the pump adapted to displace fuel in proportion responsive means for moving one element, a manually operated means for moving the other element into one of two positions so that there is a power mixture range and a cruising lean range manually selectable but which at the same time is subject to control by the temperature responsive means. a

23. A device as set forth in claim 16 in which there is a spring loaded poppet valve adapted to modify the relationship between the pressure differential across the restricted passage and the fuel fiow through the pump in response to the speed of the engine.

24. A device as set forth in claim 16 in which there is a second fuel pump adapted to create the source of fuel under pressure whereby the fuel pressure is maintained at the inlet to said fuel measuring valve.

25. .A device as set forth in claim 16 in which the pump adapted to displace fuel in proportion to the revolutions per minute of the engine is provided with a variable restriction, the flow through which creates a pressure drop across the said restriction, and manually operated means for selecting the maximum and minimum areas of said variable restriction.

26. A device as set forth in claim 16 in which the pump adapted to displace fuel in proportion to the revolutions per minute is provided with a variable restriction, the flow through which creates a pressure drop across said restriction. manually operated means for selecting the maxi mum and minimum areas of said variable restriction, and means responsive to the flow of fuel past said fuel measuring valve for automaticall restoring the variable restriction to its minimum position whenever the flow exceeds a predetermined value to prevent the operation at high power output with minimum fuel air ratios.

27. A fuel metering device for an internal combustion engine having an inlet manifold comprising an engine driven fuel pump adapted to raise the pressure of fuel, a fuel passage leading therefrom, a fuel measuring valve therein in free communication with said fuel pump, a restricted passage, a second engine driven pump adapted to displace fuel in proportion to the engine revolutions per minute and connected to said restricted passage so as to pump fuel through said restricted passage, a moving wall, two chambers located one On each side of said wall, one chamber being connected to the high pressure side of the said second pump and on the other being connected to the low pressure side of said second pump, a second moving wall connected with the first moving wall, two chambers located one on each side of said second wall, one of said last mentioned chambers being connected to the pres sure on the upstream side of the fuel measuring valve and the other chamber located on the other side thereof being connected to the downstream side of the fuel measuring valve, a second valve located in the fuel passage downstream from the fuel measuring valve and adapted to be opened and closed by the movement of said moving walls so as to control the pressure difference. across said measuring valve, to balance the pressure created by said second pump, a fuel outlet for said second valve, and means responsive to the manifold air pressure for opening and closing said fuel measuring valve.

' CARL F. SCHORN.