US2566012A - Carburetor - Google Patents

Description

Aug. 28, 1951 A. H. wlNKLER E-rAl.

CARBURETOR Filed Oct. l5, 1949 INI/ENTORS /kfer M//N/(LE/e l l. .vz .z

ATTORNEY Patented Aug. 2s, 1951 `2,566,012

UNITED STATES PATENT OFFICEI CARBURETOR Albert H. Winkler and William E. Kelsey, Elmira, N. Y., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application october 15, 1949, serial No. 121,493

l 10 Claims. (Cl. 123-25) The present invention relates to a fuel system portion 44 of shaft 48. On the intake side oi for internal combustion engines, and more par-X the centrifugal pump is a vapor bleed 48 which is ticularly to a control mechanism for fuel meterconnected by a conduit 48 to the fuel supply ing devices such as those disclosed in U. S. Patent tank to prevent vapor locking of the pump, par- 2,.452,627 issued on November 2, 1948, and appli- 5 ticularly when the engine is operating under high cation Serial No. 751,288 filed May 29, 1947. Fuel temperature conditions. metering devices of the type disclosed in said During the operation of the engine, the prespatent and application basically deliver fuel to sure in conduit 24 is at all times greater than the engine at a rate directly proportional to the the inlet pressure of pump 22 by an amount speed of the engine and consequently deliver fuel l directly proportional to the square of the improportionally to the theoretical maximum volupeller speed, and since the impeller is driven at metric efficiency of the engine. It is, therefore, engine speed, the increase in pressure is directly seen that if the fuel delivery is not corrected to proportional to the square of engine speed. The allow for the decrease in volumetric efiiciency of pressure in conduit 28 and chamber 30 during the engine, particularly at the higher speeds, the engine operation is always less than the pressure fuel-air ratio would become richer, perhaps to in conduit 24, the differential in the pressures a point where engine perfomance and economy being the effective metering head across meterwould be appreciably affected. The present ining orifice 26. The pressure in chamber 38 is vention, therefore, has as its principal object determined by the pressure maintained in chamtoprovide acontrol mechanism for correcting the ber 58 which is separated from chamber 30 by ,fuel delivery in the aforementionedsfuel meterflexible diaphragm 34 and valve 33, said valve ing devices to compensate for the decrease inl being adapted to move to and-from the inlet end volumetric eiilciency of the engine, particularly of nozzle 32 to vary the capacity of said inlet at the higher speeds. Another object of the inas the pressure increases and decreases in chamvention is to provide a control mechanism for a ber 58, thus increasing and decreasing the presfuel system for varying the fuel delivery in acsure in chamber 38 to correspond to that in cordance with engine requirements. Further obchamber 58. jects and advantages oi the present invention Chamber 5l! is connected with passage 20 on will become apparent from the following descripthe anterior side of the impeller by a conduit tion taken in conjunction with the accompany- 30 52 having a restriction 54 opening directly into ing drawing, wherein one embodiment of our inchamber 58 and with conduit 24 on the posterior vention is shown schematically in combination side of said impeller by conduit 56. orifice 58, with a fuel metering device of the type disclosed chamber 88 and conduit 52. The pressure of the in the aforementioned patent and application. fuel in conduit 58 and chamber 58 is controlled Referring more specifically to the drawing, nuby a tapered valve 84 in orifice 58 connected to meral III designates the main body of the fuel or formed integrally with a iluted valve stem metering device, I2 a throttle valve, I4 an air 8E which is slidably received in a spring 68 and inlet, and 8 a mixture outlet of the induction secured at its outer end to a flexible diaphragm passage for an internal combustion engine (not 18 and stilfening members 12 and 14. The chamshown) Fuel is supplied to the metering device ber 68 is connected directly with the impeller outthrough a. conduit I8 from a source such as a let pressure in conduit 24 by conduit 82 and is, pump or tank (not shown) at a substantially therefore, subjected to the unmetered fuel presconstant pressure and is delivered through consure which constantly urges diaphragm III in duit 28 to the inlet of a centrifugal pump 22 the directiontoopen valve 84. which delivers the fuel at an increased variable With the fuel flowing through orifice 58, paspressure through conduit 24, main metering orisage 56. chamber 58 and orifice 54, a pressure ce 26, conduit 28. chamber 38 and fuel discharge is created in chamber 58 of a value intermediate nozzle 32 to the induction passage on the engine the unmetered fuel pressure in conduit 24 and side of the throttle valve. The pressure in said the impeller inlet pressure in passage 20, the chamber is regulated by a valve 33 which is con- .tu value of this intermediate pressure depending trolled by a flexible diaphragm 34 and is adapted upon the relative sizes of orifices 54 and 58. to seat 0n the inlet of nozzle 32. The effective Consequently, if orifice 58 has an effective area size of the main metering orice is controlled by equal to that of orifice 54, the pressure in chama valve 35, such as the one disclosed in applicaber 58 will remain substantially half-way betion Serial No. 747,113 iled May 9, 1947. tween the pressure of the unmetered fuel in con- The centrifugal pump 22 consists of a fuel duit 24 and the pressure of the fuel in conduit chamber 38 and an impeller 38 mounted on shaft 28 anterior to the impeller irrespective of vari- 48 which is journaled in pump housing 42 and is ations in impeller speed. adapted to be driven by the engine through a 'I'he position of valve 84 in orice 58 is conshaft, cable or the like connected to the reduced trolled in accordance with the position of the throttle valve I2 through a spring 00 and a cam 02 secured to the throttle valve shaft 84 and in accordance with the speed of the engine through the pressure of the fuel on the outlet side of the impeller transmitted through conduit 62 to chamber 60. 'I'he contour of cam 02 is such that the eiective area of orifice 53 is decreased by the opening movement of throttle valve I2. It is seen that when the throttle valve is moved in the opening direction, the effective size of orice 58 is restricted to an effective area less than that at closed throttle by tapered valve 64 'so that the pressure in chamber 50 more nearly approaches the impeller inlet pressure. As a result of the unbalanced condition ycreated between chambers 30 and 50 as the throttle valve is opened, diaphragm 34 moves toward chamber 50 and away from the inlet of discharge nozzle 32. permitting a greater discharge of fuel into the induction passage. When the throttle valve is moved in the closing direction, the effective area of orifice 53 is increased, causing the pressure of the fuel in chamber 50 temporarily to exceed that of the fuel in chamber 30. The diaphragm 34 and valve 33 consequently move toward the nozzle inlet, restricting the discharge of fuel from chamber 30 so that the pressure in said latter chamber increases until it becomes equal to the pressure in chamber 50. Further, in the event the pressure of the metered fuel in chamber 30 should tend to exceed the pressure of that behind the diaphragm 54, as a result of increased fuel delivery by the impellerthe diaphragm will move away from the nozzle inlet, permitting the excess fuel to discharge into the induction passage at an increased rate such that the pressures on either side of the diaphragm will again become substantially equalized. l

The position to which valve B4 is moved during the movement of the cam 82 is modified by the pump outlet pressure transmitted through conduits 24 and 62 to chamber 00 so that as the pump outlet pressure increases with an increase in engine speed, diaphragm is moved downwardly, as shown in the drawings. in the direction to open valve 04. The opening of valve 64 causes the pressure in chamber 50 to increase and urge valve toward closed position and limit the flow of fuel to the engine to compensate for the decrease in the volumetric efficiency of the engine,` particularly at the higher engine speeds.

In the present fuel metering device, an increase in fuel supply pressure causes a corresponding increase in the fuel pressure throughout the entire system; consequently. in order to prevent a general increase in pressure throughout the system from opening valve 6 4 and thereby leaning out the fuel-'air mixture, a chamber 30 connected to the fuel inlet conduit I3 by conduit 32 maintains the pressure on the lower side of diaphragm 10 at a value which is at all times equal to the fuel supply pressure. By this arrangement, for any given impeller speed, a constant differential is maintained across said diaphragm regardless of any variations in the fuel supply pressure. A diaphragm S4 forms the lower wall of chamber 30 adjacent cam 32 to permit the action of said cam to be transmitted through spring 80 to valve i4; The calibrationof spring 8l may be selected to give the desired correction in fuel delivery for any particular engine.

When the engine becomes inoperative and the impeller is no longer pumping fuel from conduit into conduit 24 andthence into chamber 30,

4 the pressures of the fuel in chambers 30 and 50 remain substantially equal to one another, permitting diaphragm 34 in effect to float between the two chambers. Thus, if no means were provided to prevent fuel from discharging into the induction passage, a small quantity of fuel would seep between the valve 33 and the inlet of discharge nozzle 32 and might in time ood the engine. .To prevent this, a spring 30-Y is placed behind a diaphragm |00 to urge said diaphragm against diaphragm 34 and thereby to seat valve 33 over the inlet of nozzle 32. Under certain engine operating conditions. the temperature may become so high that the absolute fuel pressures in the system and consequently in chambers 30 and 50 will increase to a point where spring 93 alone could not seat said valve over the inlet of discharge nozzle 32 when the engine is shut off. To offset such high pressure in chambers 30 and 50, the tank pressure is transmitted through conduits 48 and 102 to chamber |04 in which spring 98 is located. Thus, when the engine is inoperative, the pressures in the three chambers are equalized so that the effective force of spring 90 is always sufficient to seat valve 33.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and arrangements of parts may be made to suit requirements.

We claim:

l. In a fuel supply system for an engine having an induction passage with a throttle therein: a conduit having a discharge nozzle in said induction passage; 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; a discharge valve between said orifice and said nozzle; a passageway having two spaced restrictions therein communicating with the conduit anterior and posterior to said pressure varying means for creating a control pressure; a member responsive to metered fuel pressure and to said control pressure. for regulating said discharge valve; and a means responsive to the movement of the throttle and to the pressure in said conduit between said pressure varying means and said metering orifice for varying the effective size of one of said restrictions.

2. In a fuel supply system for an engine having an induction passage with a throttle thereinz a conduit having a discharge nozzle in said induction passage; a means for varying the pressure o f the fuel in said conduit in accordance with engine speed; a discharge valve between said pressure varying means and said nozzle; a passageway having two spaced restrictions therein communicating with the conduit anterior and posterior Pto said pressure varying means for creating a control pressure; a member responsive to said control pressure for regulating said discharge valve; and a means responsive to the movementof the throttle and to the pressure on the downstream side of said pressure varying means for varying the effective size of one of said restrictions.

3. In a fuel supply system for an engine having an induction passage: a conduit having a discharge nozzle in said induction passage; a means for varying the pressure of the fuel in said conduit in accordance with engine speed; a discharge valve between said pressure varying means and said nozzle; a passageway having two spaced restrictions communicating with the conduit anterior and posterior to said pressure varying means for creating a control pressure; a member responsive to said control pressure for regulating the discharge valve; a control valve for varying the effective size of one of said restrictions; a yieldable means for urging said control valve toward closed position; and a pressure responsive means adapted to be subjected to the pressure on the downstream side of said pressure varying means for urging said valve toward open position.

4. In a fuel supply system for an engine having an induction passage; a conduit having a discharge nozzle in said induction passage; a means 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 discharge valve between said oriiice and nozzle; a passageway having two spaced restrictions therein communicating with the conduit anterior and posterior to said pressure varying means for creating a control pressure; a member responsive to metered fuel pressure and to said control pressure for regulating said discharge valve; a control valve for varying the effectivesize of one of said restrictions; a yieldable means for urging said control valve toward closed position; and a pressure responsive means operatively 'connected to said control valve and adapted to be subjected in the valve opening direction to the pressure posterior to said pressure varying means and in the valve closing direction to the pressure on the anterior side of said pressure varying means.

5. In a fuel metering device for an engine having an induction passage with a throttle therein: a conduit for delivering fuel from a source to said induction passage; animpeller in said conduit having a fuel inlet and a` fuel outlet; a discharge valve in said conduit on the outlet side of said impeller; a pasageway communicating with said conduit on the inlet and outlet sides of said impeller and having two spaced restrictions therein; a pressure responsive means adapted to be subjected to the pressure existing between said restrictions for controlling said discharge valve; and a means responsive to the movement of the throttle and to the pressure on the outlet side of said impeller for varying the effective size of one of said restrictions.

6. In a fuel metering device for an engine having an induction passage with a throttle therein: a conduit for delivering fuel from a source to said induction passage; an impeller in said conduit having a fuel inlet and a fuel outlet; a discharge valve in said conduit on the outlet side of saidy impeller; a passageway communicating with said conduit on the inlet and outlet sides of said impeller and having two spaced restrictions therein; a pressure responsive means subjected to the pressure existing between said restrictions for controlling said discharge valve; a control valve for varying the effective size of one of said restrictions; a yieldable means for urging said control valve toward closed positions; and a pressure responsive means adapted to be subjected to the pressure on the outlet side of said impeller for urging said valve toward open position.

7. In a fuel metering device for an engine having an induction passage: a conduit for delivering fuel from a source to said induction passage; an impeller in said conduit having a fuel inlet and a fuel outlet; a metering orifice in said conduit on the outlet side of said impeller; a discharge valve in said conduit on the downstream side of said metering orifice; a passageway communicating with said conduit on the inlet and outlet sides of said impeller and having two spaced restrictions therein; a pressure responsive means subjected to the pressure existing between said restrictions for controlling said discharge valve; a control valve for varying the effective size of one of said restrictions; a yieldable means for urging said control valve toward closed position; and a pressure responsive means operatively connected to said control valve and adapted to be subjected in the valve opening direction to the pressure on the downstream side of said impeller and in the valve closing direction to the pressure on the upstream side of said impeller.

8. A fuel metering device comprising a fuel supply conduit having in series therein an impeller, a metering orice, and a discharge valve; a passageway communicating with said conduit anterior. and posterior to said impeller and having two restrictions therein; a means responsive to the pressure between said restrictions for controlling said discharge valve; a control valve for varying the eifective size of one of said restrictions; a yieldable means for urging said control valve toward closed position; and a. pressure responsive means adapted to be subjected to the pressure on the downstream side of said impeller for urging said control valve toward open position.

9. A fuel metering device comprising a fuel? supply conduit having in series therein an impeller, a metering orifice, and a discharge valve; a passageway communicating with said conduit anterior and posterior to said impeller and having two restrictions therein; a means responsive to the pressure between said restrictions for controlling said discharge valve; a control valve for varying the effective size of one of said restrictions; and a pressure responsive means operatively connected to said control valve and adapted to be subjected in the valve opening direction to the pressure posterior to said impeller and in the valve closing direction to the pressure anterior to said impeller.

10. A fuel metering device comprising an induction passage having a throttle therein; a fuel supply conduit having in series therein an impeller, a metering orifice, and a discharge valve; a passageway communicating with said conduit anterior and posterior to said impeller and having two restrictions therein; a means responsive to the pressure between said restrictions for controlling said discharge valve; and a means responsive to the movement of. said throttle and to the pressure between said impeller and said metering orifice for varying the effective size of one of said restrictions.

ALBERT H. WINKLER. WILLIAM E. KELSEY.

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

UNITED STATES PATENTS Number Name Date 2,438,662 Greenland Mar. 30, 1948 2,443,527 Wirth et al June 15, 1948 2,452,627 Barfod et al. Nov. 2, 1948 2,456,605 Wirth et al Dec. 14, 1948

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