US2475156A

US2475156A - Fuel metering means

Info

Publication number: US2475156A
Application number: US721305A
Authority: US
Inventors: Carl F Schorn
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-01-10
Filing date: 1947-01-10
Publication date: 1949-07-05
Anticipated expiration: 1966-07-05

Description

N R o H c s s c.

FUEL HETERING MEANS Filed Jan. 10. 1947 Patented July 5, 1949 FUEL METERING MEANS Carl F. Schorn, Detroit, Mich., assignor'to George M. Holley and Earl Holley Application January 10, 1947, Serial No. 721,305

12 Claims. (Cl. 123-25) The object of this invention is to regulate the ratio of fuel to air in an internal combustion engine according to the speed of the engine and the density of the air entering the engine.

This case is an improvement over my Patent No. 2,397,984 which issued April 3, 1946. In this patent there is an inherent error due to the fact that the pressure drop across the apparatus is not constant Ianci therefore a variable is thus introduced into the functioning of the. apparatus so that the apparatus can not compensate 100%. In this present invention the drop across the device is maintained substantially constant.

The gure shows diagrammaticallyv the preferred form of my invention.

In the ligure III is the fuel entrance, II is the fuel outlet. I2 is the shaft which is driven at engine speed or at a fraction thereof. I3 is the main fuel pump which supplies the fuel -for the engine and this pump is driven at engine speed er at a fraction thereof. It is an auxiliary recirculating positive displacement metering fuel pump driven by the shaft I2 which creates pressures proportional to the square of the engine revolutions per minute and thus forms part of the control mechanism regulating fuel flow. This pump It draws fuel from the chamber 23, which chamber draws fuel through a restriction 23, past a contoured needle 25, from a chamber 24. Fuel is thus recirculated'in a-closed circuit to establish a pressure difference responsive to speed. I5 is a connection which admits the intake manifold pressure from the engine side of a supercharger I5@ and imposes supercharger pressure in the chamber t3 which contains a iiexible metal capsule assembly. This capsule assembly consists of evacuated elements i8. An exhaust passage I6 communicates to the chamber below the diaphragm so as to impose the exhaust :pressure on the diaphragm Il. The upper side of the diaphragm Il is subjected to the manifold air pressure in the chamber t9. The diaphragm Il thus responds to the difference between supercharger and exhaust pressures. pressure created by the engine driven pump I4, and the pressure responsive elements I'I and It, constitute the pressure elements of the speed density combination Which is the characteristic feature of this invention.

Valve I9 is the fuel metering device which is connected to the evacuated element I 8 and to the diaphragm Il. The valve I9 is located in a fuel passage 20 and controls the fuel flow from the passage 20 to the fuel outlet 2 I. The passage through the center of the valve I9 permits the These two elements, the

2 pressure to chamber I9 to be applied to the upper end of the valve I9.

The positive displacement .pump I4 creates a pressure differential across the restriction between the orifice 23 and the contour needle 25. This pressure drop varies directly with the square of the revolutions per minute of the engine by circulating fuel from the fuel pump I3, through the metering pump I4, to chamber 2li, past the restriction 23-25, back into the fuel inlet 5B. The fuel inlet 56 is the fuel outlet of the Dump I3. This fuel pump I3 has a .pressure regulating valve 58. loaded with a spring 60, connected through a pipe 63, through the shut-off valve 65 to the fuel outlet passage 34, through the pas sage 3l to the fuel valve I0 which controls the flow of fuel through the passage II to the center of the supercharger spinner, not shown, leading to the supercharger |58.

The movable needle 25 is responsive to a term perature device 26, which is located in a chamber Il!) through which compressed air flows from supercharger I58 through the chamber '43, through the pipe I'lI and escapes to the atmosphere from the chamber |10, and is adapted to Y control the area of the restriction 23--25.

A diaphragm 2l responds to the pressure differential across the restriction 23-25 since the chamber 28, located to the right of diaphragm 2l, is connected through the passage 29 to the fuel inlet pressure in outlet 56. The area of the fuel screen 68 is such that the pressure drop therethrough is negligible as the quantity bypassed past the variable orifice 23-25 is relatively small.

The chamber 3l, to the right of diaphragm 30, communicates through passage Il to the fuel in passage 2li, therefore, the drop in pressure acting on the diaphragm 3u is the same as the drop across the metering valve I9. Diaphragme?! and 30 are connected to each other by means of the shaft 32. Connected to the diaphragm 3D is the balanced pressure control valve 33. When the engine speed causes an increase in the pressure drop across diaphragm 27, the shaft 32 and diaphragm 30 move to the right and valve 33 moves to the left to increase the fuel discharge opening from chamber 2i to outlet passage 3d. This causes an increase in the pressure drop across the There is then maintained an adequate pressure in the passage 34. The tank 12 forms the low pressure outlet from the passage 65 and is open to the atmosphere. The main fuel entrance I is also at a low pressure similar to that existing in the fuel tank 12.

A fuel venturi 38 in the passage 20, leading to the valve I9 creates a pressure difference which responds to the ow of fuel. The pressure of the fuel entering the venturi 38 is applied to the left hand side of the diaphragm 39 through passage 14 and the decreased pressure in the throat of the venturi 38 is applied to the right hand side of a diaphragm 39 through the passage 40, Diaphragm 39 is supported by spring 4| 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.

This fuel flows along the passage 18 and past the diaphragm 18, and then around-the projection at the end of the tapered needle 42. The end of the projection of the needle 42 is provided with a taper 80 which controls the flow of water f-rom the water entrance 82, past the valve 84 mounted on the diaphragm 78, through the passage 86, past the needle 80, into the passage 34. The valve seat 84 on the diaphragm 18 responds to pressure in the water inlet 82 and shuts off the flow of fuel through the fuel passage 16 s'o that the diaphragm 39 controls the admission of extra fuel to prevent knock and alternatively controls the supply of water or some equivalent uid to prevent knock.

The valve 46, shown in the upper left hand corner, is the fuel mixture control valve and is shown in the full rich position. In this full rich position the .passage-.65 is connected 'through the valve 46 to the chamber 43, above the diaphragm 44, which diaphragm 44 is connected to the movable restriction 23. Adjustable spring 48 pushes the diaphragm 44 downwardly. The fuel entrance pressure in passage 56 is transmitted through the passage 88 to the under side of the diaphragm 44. There is a smaller diaphragm 90 also connected to the movable restriction 23 and the lower side of this diaphragm 90 is subjected to the pressure in the 4chamber 24. The upper side of the diaphragm 90 is subjected to the pressure in the passage 88 which is equal to the pressure in the fuel entrance 56. An adjustable stationary stop 94 is adapted to engage with an adjustable movable stop 92 carried on the end of the restriction 23. The downward movement of the movable restriction 23 in response to the spring 48 is brought to a stop when the movable stop 92 encounters the adjustable stop 94. The upward movement of the movable restriction 23 is adjusted by the stationary adjustable stop 96.

The shut-off valve 64 is rotated when it is desired to shut the mechanism down and in the position shown it is in the operating position.

When it is desired to transfer from full rich I the valve 23.

Idle system In the idle system the diaphragm 98, vshown f sage |08 rises.

4 immediately below the shut-oi! valve 84, carries the idle needle |00 and the two opposing springs |02 and |04 maintain the needle |00 in the neutral position. Passage |08 admits the pressure in the chamber 24, to the left hand side of the diaphragm 21. Passage |06 is connected to the right hand side of the diaphragm 98. The passage |08 is connected to a chamber at the same pressure as the pressure in passage 88 and thus imposes the pressure in the fuel entrance -56 on the left hand side of the diaphragm 90 so that at low speed, when idling, the valve |00 is open and when not idling valve |00 is closed. The spring |02 is more powerful than spring |04. The fuel then flows through |08 to the right, past the needle |00, up the passage 34, past the valve 10 to the passage II. When the speed of the engine increases, valve |00 shuts because the pressure in chamber 24 rises and hence the pressure in pas- When the fuel pump |4 is operating at a low speed, valve |36 is seated so as to prevent fuel flowing from the fuel pump I4 to the fuel chamber 24. The spring |40 seats the valve |36, the restriction |38 then delivers alittle fuel to the p-assage 88 and returns the fuel to the fuel entrance 56. Hence, during the slow speed (idling) operation the fuel metering is performed by the idle valve |00.

Accelerating system by the shaft ||6. Shaft |I8 and cam II2 are rotated anti-clockwise when the air throttle |51 is open. This is accomplished by suitable link motion. The diaphragm |20, connected to the roller II4, is the left hand wall of the chamber |22 which forms the acceleration fuel pump. Fuel is admitted past the restriction |24 which is connected to the passage 88, which is connected to the fuel entrance 56. Fuel is discharged from the chamber |22 whenever the throttle is closed and fuel flows past the valve |26 which is seated by means of the spring |28. Whenever the throttle is open chamber |22 is enlarged and the diaphragm |30 moves to the left and carries with it the valve |32. Fuel is thus admitted from the passage 88 past the acceleration restriction |34 to the main fuel'passage 34.

Operation When the mixture control valve 46 is in the position shown, that is, in the full rich position, fuel entering at I0 is raised in pressure by the pumps I3 and I4 and acts on diaphragm 2,1, which pushes rod 32 to the right and opens valve 33, this lets fuel for the engine into passage 34 and past the diaphragm 35 to the fuel outlet I|. The pressure drop across the restriction 23-26 and, therefore, the drop across diaphragm 21 and 30 and the valve I9 varies (for a given temperature) as the square of the engine speed. The flow past the valve I9 at any given opening will vary as the 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.

Assuming that this device and the power plant it controls are mounted upon a plane, then as the plane ascends, the pressure below the diaphragm |1 falls and thereby causes a relative decrease in the .capsule height at a given manifold air pressure. This causes the valve I9 to further given engine speed and manifold pressure) causedby 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 and decreasing the air density.

When increased engine speed and manifold pressure, the increase in the fuel ow through the fuel venturi 38 causes the pressure drop across diaphragm 39 to increase until the strength of passes valve 42 and is admitted to the engine.

To operate at better economy, the valve 46 is manually rotated anti-clockwise into the cruise lean position and the drop across the restriction f3 is lowered because the pressure existing in chamber it is increased as the passage iin now communicates with the chamber 43 and with the pressure in the fuel entrance 5B. After a certain fuel iiovv is reached in the venturi 38 there is a slight decrease in pressure in the chamber 43. This decrease in pressure in the chamber 43 has a tendency to make the mixture ratio richer. Just as the ratio of the valve 46 places the low pressure passage 65 in communication with the chamber i3 it also has a tendency to make the fuel ratio richer. 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 cylinder and the intake manifold pressure, which are the controlling factors in determining its desired fuel supply.

What I claim is:

l. A fuel metering device for an internal combustion engine, said device having a constant pressure discharge valve, an engine driven fuel supply pump discharging into the fuel inlet of said device, pump pressure regulating means for said pump adapted to maintain a constant pressure drop between the fuel inlet to said device and the pressure side of said constant pressure dis-- charge valve, a fuel measuring valve therein, a restricted passage, an engine-driven ancillary 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 4being connected to the high pressure side of the said ancillary 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 chambersbeing connected to the pressure on the upstream side of the fuel measuring valve and the other side thereof being connected to the downstream side of the fuel measuring valve, a second valve located in the fuel the spring ti is overcbme and additional fuel passage downstream from the fuel measuring valve and adapted toV be opened vand closed by the movement of said movingwalls so as to control the pressure difference across said measuring valve, to balance the pressure created by said ancillary 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 l there is a second fuel passage and a second fuel .measuring valve located in parallel with the rst fuel measuring valve and rstfuel 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 pre determined value. g

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 rst fuel measuring valve and adapted to supply the fuel required for idling, means responsive to the enginedriven ancillary 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 waterv entrance, a water passage connecting said entrance to fuel outlet, an automatic valve in said Water passage controlling the water iiow, means responsive to the rate of fuel iiow through said fuel passage past said fuel measuring valve for opening said Water valve.

5. A device as set forth in claim l, in which there is a second fuel passage and a second fuel measuring valve means located in parallel with the first fuel measuring valve and first 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 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 temperatures, the pressure generated by the enginedriven ancillary pump for any given revolutions per minute will be lower than at low temperature.

'7. A device as set Iforth in claim 1 in which the means responsive to the supercharger pressure is modified by means responsive to the dierence between th supercharger pressure and the ypressure of the exhaust.

8. A device as set forth in claim 1 in which' the ancillary pump adapted to displace fuel in proportion to the revolutions per minute is provided with a variable restriction formed between two elements consisting of a movable needle and 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.

9. 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 ilow through the ancillary pump in response to the speed of the engine.

10. A device as set forth in claim 1 in which the ancillary 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 vthe said restriction, and manually means for selecting the maximum and minimum operated areas of said variable restriction.

1l. A device as set forth in claim 1 in which the ancillary pump adapted to displace fuel in proportion to the revolutions per minute is provided with a variable restriction, the ilow 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 ow of fuel past said fuel measuring valve for automatically restoring the variable restriction to its minimum position whenever the ow exceeds a predetermined value to prevent the operation at high power output with minimum fuel air ratios.

12. A fuel metering device for an internal combustion engine, said device having a constant passage, an ancillary 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 said ancillary pump and on the other being oonnected to the low pressure side of said ancillary 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 tothe 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.

REFERENCES CITED UNITED STATES PATENTS Name Date Schorn Apr. 9, 1946 Number