US3263975A

US3263975A - Charge forming device having a constant level device

Info

Publication number: US3263975A
Application number: US334268A
Authority: US
Inventors: Wu Tao-Yuan
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1963-12-30
Filing date: 1963-12-30
Publication date: 1966-08-02
Anticipated expiration: 1983-08-02
Also published as: GB1037248A; DE1937126U

Description

Aug. 2, 1966 TAO-YUAN wu 3,263,975

CHARGE FORMING DEVICE HAVING A CONSTANT LEVEL DEVICE Filed Dec. 50, 1963 Iii-9;;

7:40 YUAN WU v INVENTOR.

ATTOR/VIYS United States Patent 3,263,975 CHARGE FORMING DEVICE HAVING A CQNSTANT LEVEL DEVICE Tao-Yuan Wu, Ann Arbor, Mich, assignor to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Dec. 30, 1963, Ser. No. 334,268 2 Claims. (Cl. 261-70) This invention relates to a charge forming device for an internal combustion engine and more particularly to a constant level device for maintaining a uniform fuel head in a fuel bowl of the charge forming device.

The fuel metering circuits of most conventional charge forming devices rely upon a uniform fuel head for effective operation. A float operated valve generally i provided to maintain a consistent fuel level in the fuel bowl in a conventional charge forming device. The fuel in the fuel bowl of a charge forming device of a motor vehicle, however, is subjected to external forces that cause the fuel level to change artificially without a significant change in the total volumn of fuel. For example, during acceleration, deceleration, operating on inclines or rounding curves, the fuel level is temporarily disturbed. Under the aforementioned conditions the float operated valve may either open prematurely or remain closed longer than is desirable. Premature opening of the valve will cause a surplus of fuel to flow into the induction passage of the engine with attendant flooding whereas delayed opening of the valve will cause fuel starvation. Each condition, therefore, results in unsatisfactory engine operation.

It is, therefore, the principal object of this invention to provide a float operated valve for a charge forming device that is relatively insensitive to temporary disturbances in the fuel level as are caused by vehicle operation.

It is a further object of this invention to provide a float operated valve that provides a substantially uniform head of fuel above a main metering jet in a charge forming device fuel bowl regardless of external forces acting upon the charge forming device.

A charge forming device embodying this invention has a fuel bowl, an induction passage and fuel discharge circuit means for discharging fuel from the fuel bowl into the induction passage. A fuel inlet is provided in the fuel bowl and a valve member controls the admission of fuel from the fuel inlet into the fuel bowl. A float is buoyantly supported by the fuel in the fuel bowl. Lever means operatively connect the float to the valve member for moving the valve member between an opened and a closed position upon movement of the float in a first plane. The float is freely movable upon the lever means in another plane without affecting the position of the valve member.

Further objects and advantages of this invention will become more apparent when considered in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a cross sectional view taken along the axis of an induction passage of a charge forming device embodying this invention.

FIGURE 2 is a cross sectional view taken along the line 22 of FIGURE 1.

FIGURE 3 is a cross sectional view taken along the line 33 of FIGURE 1.

FIGURE 4 is a perspective view of the float supporting lever assembly.

Referring now in detail to the drawings, the body portion of a charge forming device embodying this invention is identified generally by the reference numeral 11. The body portion 11 contains a fuel bowl 12 and an induction passage 13 having a venturi section 14. A throttle valve 15 is rotatably supported by a throttle valve shaft 16 Patented August 2, 1966 in the lower portion of the induction passage 13. A cover plate 17 is afiixed to the body portion 11 in a suitable manner Wtih a gasket 18 interposed therebetween. The cover plate 17 extends across the fuel bowl 12 adjacent to an integral air horn portion 19. The air horn portion 19 forms an air inlet passage 21 that registers with the induction passage 13 in the body portion 11.

A main metering jet 22 having a calibrated orifice 23 is positioned in the lower surface of the fuel bowl 12 along the vertical center of the charge forming device. The main metering jet 22 is positioned at the mouth of vertically extending passage 24 formed in the body portion 11 below the fuel bowl 12. The passage 24 terminates at a passage 25 that extends upwardly and transversely through the body portion 11 to a main fuel well 26. A booster venturi nozzle assembly 27 is affixed to the body portion 11 with a small discharge venturi 28 positioned in the induction passage 13 contiguous to the main venturi section 14. Fuel and air metering tubes 29 and 31 depend into the main fuel well 26 from the booster venturi nozzle assembly 27. Fuel is discharged from the main fuel well 26 into the induction passage 13 by the nozzle assembly 27 in a known manner.

A tapped hole 32 is formed in the body portion 11 at one side of the fuel bowl 12 above the normal fuel level. A fuel inlet fitting 33 is threaded into the tapped hole 32 with a gasket 34 positioned between the body portion 11 and an enlarged portion 35 of the inlet fitting 33. Fuel is introduced under pressure from a fuel pump (not shown) through a fuel passage 36 that extends through the inlet fitting 33. The fuel passage 36 terminates at a restricted portion 37 formed adjacent a bore 38 that extends into the fuel bowl 12. A needle valve 39 having flattened sides 40 is slidably received in the bore 38. The needle valve 39 has a tapered surface 41 that is adapted to contact the restricted portion 37 to preclude the flow of fuel into the fuel bowl 12. When needle valve 39 is axially spaced from the restricted portion 37 fuel may flow into fuel bowl 12 through the clearance between flattened sides 40 and the bore 38.

The needle valve 39 is actuated by a float assembly, indicated generally by the reference numeral 42 to provide a uniform head of fuel in the fuel bowl 12 above the main metering jet 22. The float assembly 12 includes a float 43 that is buoyantly supported by the fuel in the fuel bowl 12. The float 43 is supported for pivotal movement with respect to the body portion 11 along two pivotal axes by a lever assembly shown in greater detail in FIGURE 4.

The lever assembly includes a lever having a horizontally extending first part 44 that terminates at a vertically extending second part 45. The vertically extending second part 45 terminates at a horizontally extending third part 46 that is parallel to the first part 44. The third part 46 extends through a cylindrical bushing 47 formed in the float 43 below its center of buoyancy in the gasoline in the fuel bowl 12. Snap rings 48 and 49 axially locate the float 43 upon the third lever part 46 and permit pivotal movement of the float 43 upon the lever part 46. The lever part 46, therefore, determines a first pivotal axis of the float 43.

A cylindrical part 511 of a sheel metal bracket receives a pin 52. The cylindrical part 51 has an upturned tab 53 formed with an aperture 54 that receives the outer end of the first lever part 44. The first lever part 44 is secured within the upturned tab 53, as by a weld 55. The pin 52 is journaled in

arcuate slots

56 and 57 formed in the body portion 11 adjacent the outlet opening of the bore 38. The lever and float 53 may rotate with the pin 52 to form a second pivotal axis for the float 43. Pivotal movement of the float 43 about this axis is transmitted into motion of the needle valve 39. For this purpose, the tab 53 contacts an arcuate head 58 of the needle valve 39. The normal fuel pressure in the passage 36 will urge the needle valve 39 against the tab 53.

As fuel is discharged from the fuel bowl 12 into the induction passage 1'3, the level of fuel in the fuel bowl 12 will be depleted. This causes the float 43 to pivot in a clockwise direction about the pivotal axis defined by the pin 52. Pivotal movement about this axis causes the tab 53 to move away from the inlet fitting 33. The fuel pressure acting on the needle valve 39 urges the needle valve 39 toward the tab 53. The tapered surface 4 1 of the needle valve 39 is then moved away from the restricted portion 37 of the inlet fitting 33 and fuel is permitted to flow into the fuel bowl 12 until the float 43 returns to the preselected height. When this occurs, the needle valve 39 will be again moved int-o contact with the restricted portion 37 and preclude the flow of fuel into the fuel bowl 12.

It should be readily apparent that under certain conditions the level of fuel in the fuel bowl may be disturbed Without a change in the volume of fuel in the fuel bowl. Such a change in level is represented by the broken line in FIGURE 2. When this condition occurs in a norm-a1 charge forming device the float has a tendency to raise or fall, depending upon the geometry of the system. Movement of the float in the conventional carburetor will be transmitted into movement of the needle valve 39 to cause a change in the fuel volume within the fuel bowl 12. This will cause either starvation or flooding of the engine. In a carburetor embodying this invention, however, the float 43 may pivot about its axis on the third lever portion 46 to the dotted line position shown in FIGURE 2. This pivotal movement of the float 43 does not cause any movement of the needle valve 39. It is additionally noted that the pivotal axis defined by the third lever portion 46 lies in substantially the same vertical plane as the orifice 23 of the main metering jet 22. The level of fuel above the main metering jet 22 will 4 thus be relatively unaffected by the displacement of the fluid.

It is to be understood that this invention is not limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.

I claim:

L A charge forming device comprising a body having a fuel bowl and an induction passage,

a fuel inlet into said fuel bowl,

valve means movably positioned in said fuel inlet,

a float adapted to be buoy-antly supported by fuel in said fuel bowl,

a lever positioning said valve means to control fuel flow through said fuel inlet, said lever being pivotally connected to said float about a substantially horizontal first axis below the center of buoyancy of said float, means pivotally mounting the lever about a second axis at a right angle to the first axis for moving the valve means, and

a fuel outlet from said fuel bowl for discharging fuel into said induction passage.

2. The charge forming device of claim 1 in which the float has a single cylindrical bushing mounted therein, said bushing being located in the vertical plane that contains the center of buoyancy of said float, and the lever is pivotally located in said bushing.

References Cited by the Examiner UNITED STATES PATENTS 1,168,783, 1/ 1916 Bucker.

1,270,213 6/19'18 Roesch r l37-434 X 2,430,719 l'l/1947 Johnson et al. l374-34 X 2,729,436 1/ 1956 Norris 26172 X 3,071,354 1/1'963 Newman 261-72 X HARRY B. THORNTON, Primary Examiner.

R. R. WEAVER, Assistant Examiner.

Claims

1. A CHARGE FORMING DEVICE COMPRISING A BODY HAVING A FUEL BOWL AND AN INDUCTION PASSAGE, A FUEL INLET INTO SAID FUEL BOWL, VALVE MEANS MOVABLY POSITIONED IN SAID FUEL INLET, A FLOAT ADAPTED TO BE BUOYANTLY SUPPORTED BY FUEL IN SAID FUEL BOWL, A LEVER POSITIONING SAID VALVE MEANS TO CONTROL FUEL FLOW THROUGH SAID FUEL INLET, SAID LEVER BEING PIVOTALLY CONNECTED TO SAID FLOAT ABOUT A SUBSTANTIALLY HORIZONTAL FIRST AXIS BELOW THE CENTER OF BUOYANCY OF SAID FLOAT, MEANS PIVOTALLY MOUNTING THE LEVER ABOUT A SECOND AXIS AT A RIGHT ANGLE TO THE FIRST AXIS FOR MOVING THE VALVE MEANS, AND A FUEL OUTLET FROM SAID FUEL BOWL FOR DISCHARGING FUEL INTO SAID INDUCTION PASSAGE.