US2446340A - Speed density carburetor - Google Patents

Description

Aug.. s, 148. AWORRJR www SPEED DENSITY CARBURETOR Filed March 9, 1946 '4/ n W www Jim 55 INVENTOR.

' H T TOAPNE Y Patented Aug. 3, 1948 UNITED sTATEs T voFFlcE.

l n T SPEED DENSITY CARBURETOR Andrew William Orr, Jr., Detroit, Mich., assigner to George M. Holley and Earl Holley 7 Claims. l

Theobject of this invention is to proportion the fuel to the air in an internal combustion engine. Specifically, the object is to control the fuel iiow by: (a) the velocity of fioW of the fuel to the engine; (blthe speed of the engine; (c) the pressure of the air entering the engine (Manifold air pressure); (d) means responsive to the temperature of the charge to control the fuel; (e) means responsive to the back pressure of the exhaust to control the fuel; (f) to provide automatic means for controlling the low speed fuel flow.

This application is a continuation in part of my co-pending application Serial No. 646,559 filed February 9, 1946.

The gure shows the preferred form of my invention.

In the iigure, l is the fuel entrance, |2 is the shaft, driven by the engine at engine speed or at some speed proportional to engine speed, which drives a vane pump I4, which delivers fuel under pressure to a passage 2'6. The pressure generated by this pump is regulated by the centrifugal governor comprising the shaft I6, balls |8 and discs -22. The annular diaphragm 24 allows fuel to escape from passage 28 past the pressure relief valve 34, through 3B, back to the fuel entrance |0. A diaphragm 33 and spring 4| and passage 42 cooperate to apply a load to the valve 34.

The fuel flows through a fuel venturi 4S, the fuel follows the path, through the passage "I6, past the valve '|8, to exit passage 80, and then flows past the equalized valve |04. The valve |04 is supported b-y the diaphragm 92. A compression spring |02 supports the diaphragm 92 so as to open the valve |04 in response to the pressure in the chamber 90, which pressure acts to supplement the compression spring |02. A second diaphragm 210 is added, plus a second compression spring 212.

The chamber 302 is formed between the diaphragms 92 and 210. This chamber 302 is connected by the pipe 98 with the restriction |00. The restriction |00 is connected to the chamber 30. Hence, a relatively low pressure sometimes is established in the chamber 302. When a low pressure 4exists in the chamber 302, a spring 212 plus Whatever pressure there may be in chamber 304, is applied to the diaphragm 92 and thus is applied to the balen-ce valve |04. The chamber 304, located above the diaphragm 210, is connected through the pipe 300 with the air entrance passage ||2. When the pressure in the chamber `98 rises, the diaphragm 210 is raised and the compression spring 2'l2 ceases to have any influence on the valve |04. The valve |04 is then moved down by the high pressure in the chamber 302 compressing the spring |02.

The balanced valve 05 guided on the cylinder @d admits fuel through the passage 08 to join the fuel passing through the passage 80. The pressure pipe i4 is connected from the outlet 2&5 from the pump i4 to the chamber 'l2 behind the diaphragm 54 which is pushed to the left by the spring |96.

The diaphragm 46 responds to a compression spring |03, acting in opposition to the depression created in the throat of the venturi 48. This depression acts in the cham-ber 50, but this pressure in the chamber 50 is slightly higher than the pressure in the venturi 43. A restriction 250 regulates the pressure in the chamber 50. A pipe 252 communicates with the chamber 50 and With a manually-controlled valve 254, which is controlled by a lever 283.

In the position shown in the drawing, the vali-'e 254 is shown in the automatic rich (A. R.) position. In this position (A. RJ, pipe 252 i-s in cmmunication with the pipe 250 through an opening 25S in the valve 254. The pipe 25S communicates with the downstream side of the venturi 48 through a restriction 260, so that the pressure in the chamber 50 is slightly greater than the pressure in the throat of the venturi 48. Dilaphragm l and the needle valve 56 control the flow of fuel thro-ugh a passage 58, this fuel ows directly through the valve 254 to the restricted passage 254 to the chamber |52 to the right of the diaphragm '04, which diaphragm is to the right of chamber l2, which chamber communi- Cates with the pressure pipe 14 as already stated.

When the lever 283 moves anti-clockwise slightly less than 45 the pipe 53 is put in com" munication with both the restricted passages 264 and 265. At the same time the passages 255 and 252 .are no longer in communication with each other so that the pressure in chamber 50 is equal to the depression in the throat of the venturi 48.

The leverZBB is connected through the link S50 with a corresponding lever |08. The lever is connected to a valve 84 which controls the flow through a pipe 98. In the A. R. position in which the valve |84 and 254 are shown fuel can not flow through the pipe S8 and can not iiow through the valve |84 because the port |82 does not connect the passage 98 with the pasn sage 383, which passage 338 is connected through the passage |46 to the pump outlet passage 20.

space labetween diaphragms 92L'and1210gwhent-he lever its is in the A. R. positiont and when the temperature is cold, is determined by the pressure to the right of the diaphragm 24 because of Element.- |30 is the restricted connection 50|). connected to the exhaust back pressure and'isV connected in series with the elements?|2`ii'fvvrhicl'i are evacuated .and located in the chamber |2liconnected through passage |22 to thesupercharger.

outlet |40.

The valve '13, which is the main fuel'control of the carburetor, is moved to the right by an increase of pressure in the-supercharger outlet |4Q actingon the element |28. Thevalve'i is moved to the left by an increase -inexhaust backpressure acting in theelemen-t |39.. The'lowpast the valve 'i8 depends on the position ofthe valve 'i8 'as thus determined, and on the pressure drop from the fuel entrance 16- to the-fuel exit-SIL This passage S23 is normally closed by 4the extension of the valve '18. Whenvthe valve 18- moves `to the left an annular port 218 opens thebypass 860.' An adjustable needle |3 regulates the low speed flow of fuel through thepassage lia-rrd this-fuel flows past the valve |04.

The fuel is discharged through apassage @uit past the fuel outlet nozzle Hi8-4 whichallows the fuel to discharge into the passage r`'I Qs'ldcwnstream from the vthrottle H9;

A' pipe 45B connects the chamber |24 with a. chamber 42E)` which c-ontains-the'temperature-responsive elementl |59. Achamber 43B contains a spring Me which opposes the' downward movef ment of the valve 284. A passage 45o-connects the chamber' 42@ with the chamber 43|).V A cham-'- ber 458 contains a compression' spring 410.1 Thel compression spring 47o opposes the movement to the left of the valve i8. A' passage 480 connects the chamber |24With the chamber 462;

Low-speed operation ln the low-speed operation, the-throttle Il!) approaches -the closed-position, the supercharger |2l no longer creates a pressure, andy the :pressure outlet |49, and therefore the pressure. in the passage |22and the pressure in the chamber 214,. becomes less than atmospheric pressure. Valve 'i8 moves overto the left and valve 2li)Y permits a small quantity of fuel to 'ovv to the 10W-speed. passage past the needle-valve i3.v When-the lever 288 and when the lever |83 are moved antclockwise about 90"v into the idle cut off position, fuel is prevented from running out of the system, that is to say, it is trappedinthe vsystem because pressure in the pipe S8 becomes equal to the. pressure in the passage |45 which is equal tothe pressure created by the fuel pump i4. Therefore the pressure in chamber 3D2 becomes great enough to cut off the ovv of fuelthrough the pipe 508 by pushing the valve JM down.

Normal operation In the position in which the` elements are shown, which is the automatic rich position, valve and prevents communication between the pase the-air;

sage 400 and the passage 500. The relatively low pressure in the chamber 3l) is then transmitted through the restriction |08, through the passage 98 to the chamber 302, thus a relatively low pressure exists in the chamber 302, and there is a relatively big pressure drop at the valve 18 and therefore the rate of flow past the valve 18 is at its maximum. This provides the automatic. rich mixture, As the'fuel flow increases through the venturilifthe fuel flow` eventually4v reaches a value at which the engine will require an excessive quantity of fuel to prevent over-heating.

This isY particularly true of air cooled engines which constitute 98% of the engines in use in When this critical fuel -ow is reached the valve moves to the right and a small quantity of additional fuel, that is, the quantity which canfiow through the restricted passage 264, is addedftoi the fuel flowing past the restriction 18.

When the valves 254 and |84 are both moved counterclockwise, approximately 45, the full pressure difference created by the venturi 48- becomes eective and therefore the valve 56v The reason for this` -opensat alower fuel flow. is that When running at the automatic lean mixturelthe danger of overheating is greater and.

therefore vthe extra fuel is needed sooner and in largerquantities., This larger quantity is provided because both the restrictions 264 and 265.v are now available for giving the lnecessary additional fuel. Whenthe valve |84 is moved 45 anti-clockwise, into the automatic lean position,`

` Temperature control When the temperature rises the valvel 284 moves down. Passage 49|) is placed in communication with the passage 5GB. Pressure in the chamber 3M increases. This'increases the pres"- sure in the pipe 98. Thus the pressure in cham'- ber 3D2-is increased which reducesthe pressure drop across the valve 18, which reduces the fuel flHOW.

What I' claim is:

1. A fuel supply means for an internal combustion engine having an inlet manifold and an air entrance leadingthereto, comprising a fuel pump, Aa fuel outlet, a fuel return bypass connecting the fuel outlet with the fuel entrance, av variable pressure relief valve located in said'return bypass, a moving Wall connected to said valve so as to be responsive to the pressure drop at said valve, engine speed responsive meansy increases the pressure drop increases and thepressure in said' fuelpump outlet increases, a movable metering restriction in said fuel outlet,

means responsive to the manifold'air pressure'y connectedto said movable metering `restriction to' open-said metering restriction as said'manihfold air! pressure increases, a second pressure regulating valve, said valve being located downstream from said movable restriction, a moving. Wall connected to said' regulating" valve, one sideofsaid'moving Wall being subject tothe-fuel pressure downstream from said movable restriction, a'chamber'on the other side of said move 2. A device as set forth in claim 1 in which there is a restriction in the last mentioned passage where it lcommunicates with the downstream side of said pressure relief valve and in which there is a temperature responsive element located in the inlet manifold and a flexible temperature responsive element connected thereto, a second passage transmitting the pressure created in the outlet from said pump to said chamber, a valve located in said passage connected to said flexible temperature responsive element so that the pressure in said chamber tends to increase at high temperature.

3. A device as set forth in claim 1 in which there is an element responsive to the difference between manifold air pressure and the engine exhaust back pressure associated with the means responsive to the manifold air pressure so that the movable metering restriction tends to yopen as the back pressure of the engine exhaust decreases.

4. A device as set forth in claim 1 in which there is a low speed fuel bypass around said movable metering restriction, a normally closed low speed fuel valve located in said bypass, a mechanical connection from said valve to said manifold air pressure responsive means whereby the low speed fuel Valve is opened at abnormally low manifold air pressures.

5. A device as set forth in claim 1 in which there is a third pressure regulating valve, said valve being located in the fuel return bypass downstream from said speed controlled pressure relief valve, a moving wall connected to said valve, a chamber on the other side of said wall, a passage connecting said chamber with the fuel entrance yielding means in said chamber engaging with said moving wall.

6. A device as set forth in claim 1 in which there is a restriction in the last mentioned passage Where it communicates with the downstream side of said pressure relief valve and in which there is a temperature responsive element located in the inlet manifold and a flexible temperature responsive element connected thereto, a second passage transmitting the pressure created in the outlet from said pump to the chamber mentioned in claim 1, a valve located in said passage connected to said flexible temperature responsive element so that the pressure in said chamber tends to increase at high temperatures, and in which there is a third pressure regulating valve, said valve being located in the fuel return bypass downstream from said speed controlled pressure relief valve, a moving wall connected to said valve, a chamber on the other side of said wall, a passage connecting said chamber with the fuel entrance yielding means in said chamber engaging with said moving wall.

7. A device as set forth in claim 1 in which there is an element responsive to the difference between manifold air pressure and the engine exhaust back pressure associated with the means responsive to the manifold air pressure so that the movable metering restriction tends to open as the back pressure of the engine exhaust falls, and in which there is a third pressure regulating valve, said valve being located in the fuel return bypass downstream from said variable pressure relief valve, a moving wall connected to said valve, a chamber on the other side of said wall, a passage connecting said chamber with the fuel entrance yielding means in said chamber engaging with said moving wall.

ANDREW WILLIAM ORB, JR.

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

UNITED STATES PATENTS Number Name Date 2,102,476 Messesson Dec. 14, 1937 2,126,709 Alden Aug. 16, 1938 2,136,959 Winfield Nov. 15, 1938 2,161,743 Heinrich et al. June 6, 1939 2,217,364 Halford et al. Oct. 8, 1940 2,281,411 Campbell Apr. 28, 1942 FOREIGN PATENTS Number Country Date 429,682 Great Britain June 4, 1935

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