US2920876A

US2920876A - Carburetor enriching device

Info

Publication number: US2920876A
Application number: US681207A
Authority: US
Inventors: Morris C Brown; Wenford E Highley
Original assignee: ACF Industries Inc
Current assignee: ACF Industries Inc
Priority date: 1957-08-30
Filing date: 1957-08-30
Publication date: 1960-01-12
Anticipated expiration: 1977-01-12

Description

Jan. 12, 1960 M. c. BROWN ET AL CARBURETOR ENRICHING DEVICE Filed Aug. 30, 1957 FIG.2.

INVENTORS MORRIS C. BROWN WENFORD E. HIGHLEY ATTORNEY CARBURETOR ENRICHING DEVICE Morris C. Brown, Pontiac, Mich., and Wenford E. Highley, Normandy, Mo., assignors to ACE Industries, In- ;orporated, New York, N.Y., a corporation of New ersey Application August 30, 1957, Serial No. 681,207 11 Claims. (Cl. 261-39) This invention relates to carburetors for internal combustion engines, and, more particularly, to means adapted to enrich the fuel mixture during starting and warming up of the engine.

Carburetors have heretofore been provided with antomatic choke controls for enriching the fuel mixture during starting and warming up of a cold engine, and also various step-up or economizer devices which serve to enrich the carbureted mixture under load conditions. These devices operate independently, except that during cold starting, the high suction produced by the choke valve may shift the step-up valve to its lean position. Accordingly, it is an object of this invention to insure rich positioning of the step-up valve during cold starting and warm-up, so that the additional fuel thus supplied may assist the starting operation.

A further object of the invention resides in the provision of a temperature responsive device controlling the suction force applied to a suction responsive step- .up device.

Another object of the invention is to provide a stepup device controlled by a temperature responsive device of a conventional automatic choke control mechanism.

The invention embodies other novel features, details of construction, and arrangement of parts which are hereinafter set \forth in the specification and claims, and illustrated in the accompanying drawings, wherein:

Fig. l is a vertical sectional View of a carburetor with a step-up device embodying features of the invention.

Fig. 2 is a detail sectional view illustrating a conventional automatic choke control mechanism.

Fig. 3 is a fragmentary vertical sectional view illustrating a modified form of the invention.

Referring now to the drawings for a better understanding of the invention, and, more particularly, to Figs. 1 and 2 therein, a downdraft carburetor is shown as comprising an air horn section 2, a main body section 3, and an outlet section 4, said sections being secured together and forming a mixture conduit 6 leading to an intake manifold of an internal combustion engine.

The main body section 3 comprises a float bowl 7 having a fuel inlet 8 controlled by a needle valve 9 which is actuated by a pivotally mounted float 1 1 to maintain a substantially constant fuel level in the bowl. Fuel is supplied from the bowl through a metering orifice 12 to a main fuel passage 13 communicating with a Well 14. A perforated tube 16 is provided in the well to supply fuel to a main fuel nozzle 17 for discharge into a primary venturi 18.

An idle orifice tube 19 is also disposed in the well 14 for the passage of fuel therefrom into an idle passage 21 leading to an idle port 22 in the mixture conduit 6 adjacent the upstream edge of a throttle valve 23. An air bleed orifice 24 leads from atmosphere to the idle passage 21. The throttle valve 23 is fixed on a shaft 26 journaled at its ends in the outlet section 4 ice and is adapted to be connected to an accelerator pedal by a suitable linkage.

An unbalanced choke valve 27 is fixed on a shaft 28 journaled at its ends in the air horn section 2 and is actuated by a conventional automatic choke control devide indicated, generally, at 29. The control device 29 comprises a housing 31 receiving one end of the choke shaft 28 for rotational adjustments by suction and temperature responsive means acting through a crank 32 fixed on the shaft.

The housing 31 is provided with a rotatably adjustable inner cover 33 secured thereto by an outer cover 34 and cap screw 36. A metallic base 37 is spaced from and secured to the inner cover 33 and provided with a bifurcated stem 38 to receive the inner end of a spirally wound, bimetal thermostat 39 which has its outer end engaging the outer oflfset end of the crank 32 to yieldably resist opening of the choke valve when the engine is cold.

A cylinder 41 is provided in the housing 31 to receive a piston 42 connected to the crank 32 by a rod 43. A suction passage 44 leads from the inner end of the cylinder, below the piston, to a port 46 in the mixture conduit 6 posterior to the throttle valve 23. A by-pass groove 47 is formed in thewall of the cylinder for the passage of air around the piston when the latter is disposed at the outer end of its stroke. A warm air passage 48 leads from a source of heated air, such as an exhaust manifold stove, through the

covers

33 and 34, and thence around the base 37 into the housing 31'.

A cylinder 49 is provided in the main body section 3 to receive a step-up piston 51 engaged by a compression spring 52. A fuel metering rod 53 is secured at one end thereof to the piston 51, and has its other end formed and disposed to vary the flow of fuel through the orifice 12 responsive to movements of the piston. A suction passage 54 leads from a suction chamber 55 in the cylinder to a cross passage 56 connected to a passage 57 having a port 58 in the mixture conduit posterior to the throttle valve 23.

The choke valve shaft 28 has one end thereof interposed in the cross passage 56 and formed with an opening 59 movable into and out of registry with the cross passage to serve as a suction control valve 60 therein to vary the pressure in the suction chamber 55.

In the operation of the carburetor step-up device for starting and Warming up a cold engine, the choke valve 27 and its valve 60 are normally held in their closed positions by the thermostat 39, while the piston 51 and fuel metering rod 43 are held in their maximum fuel flow positions by the spring 52.

Upon starting of the cold engine, the unbalanced choke valve 27 is urged to partly open position by the piston 42 against the resistance of the thermostat 39. As the engine warms up, the thermostat 39 is heated by the warm air from the exhaust manifold stove, or other source of heated air, and gradually permits the choke valve 27 and suction control valve 60 to move to their fully open positions.

(The thermostat thus serves to prevent opening of the suction control valve 60 until the engine reaches a predetermined operating temperature. After the suction control valve 60 is thus opened, intake manifold suction acts to move the piston 51 in a direct-ion to compress the spring 52, and thus move the metering rod 53 toward iw minimum fuel flow position within or adjacent the fuel metering orifice 12. When the throttle 23 is thereafter moved toward its full open position, the resultant decrease in manifold suction permits the spring 52 to return the piston 51 and metering rod 53 toward theirmaximum fuel flow positions to enrich the fuel mixture to the engine.

I 920,878 f P Fig. 3 illustrates a modified form of the invention in which asuction passage 61 leads from the suction chamber 55 in the cylinder 49 through a valve port 62 into a yalve chamber 63 in the outlet section 4. A bimetal thermostat '64, secured at one end thereof to the outlet section at 66, is provided to support and move a valve 67 relative to the valve port 62 responsive-to variation in temperature. A suction port 68 leads from the valve chamber 63 to the mixture conduit 6 posterior to the throttle valve 23.

In the operation of the modified form of step-up device illustrated in Fig. 3 during starting and warming up of a cold engine, the valve 67 is seated against the valve port 62 by the thermostat 64, and the metering rod 53 and piston 51 are disposed in their maximum fuel flow positions to enrich the fuel mixture supplied to the engine. As the. engine becomes heated to its normal operating temperature, the thermostat 64 gradually opens the valve 67 to open the suction passage 61, and thereby causes the piston -51 to move the metering rod 53 toward its -minimum flowposition'in the fuel metering orifice 12 to lean out the fuel mixture supplied to the engine. This form of the invention is otherwise similar in construction and operation to the form heretofore shown and described.

In -each form of the invention, it will be noted that the suction responsive step-up device is controlled by a temperature responsive valve means automatically operable to vary the richness of the fuel mixture responsive to engine temperature, whereby a cold engine is supplied with a relatively rich fuel mixture during starting and warming up, and a leaner fuel mixture as the engine reaches its normal operating temperature.

Certain structures have been described herein which will fulfill all the objects of the present invention, but it is contemplated that other modifications will be obvious to those skilled in the art which come within the scope of the invention as defined by the appended claims.

We claim:

1. In a fuel metering control system for internal combustion engine carburetors having a main fuel passage, choke and throttle valves, a float bowl for supplying liquid fuel through a metering orifice to said main fuel passage for discharge into a mixture conduit, valve means responsive to intake manifold suction for varying the fuel flow through said orifice, and temperature responsive means controlling said suction responsive means to provide a relatively rich fuel mixture for starting and warming up a cold engine, said suction responsive means having a suction passage, said temperature responsive means actuating a suction control valve in said suction passage.

2. A fuel metering control system according to claim 1 wherein, said suction control valve is connected to and operable responsive to movements of said choke valve in said mixture conduit.

3. A fuel metering control system according to claim 1 wherein, said suction control valve is connected to and operable responsive to movements of said choke valve in said mixture conduit, and said temperature responsive means engages and yieldably resists opening of said Choke valve.

4. A fuel metering control system according to claim 1 wherein, said suction control valve is connected to and operable responsive to movements of said choke valve in said mixture conduit, said temperature responsive means engages and yieldably resists opening of said choke valve, and othermeans responsive to intake manifold suction for urging said choke valve toward its open position.

5. A fuel metering control system according to claim 1 wherein, said suction control valve is connected to and operable responsive to movements of said choke :valve in said mixture conduit, said temperature responsive means engages and yieldablyresistsopening of said choke ,4 valve, said choke valve having a shaft, and said suction control "valve comprising one end of said shaft provided with an aperture for registry with said suction passage.

6. In a fuel metering control system for internal combustion engine carburetors having a float bowl for supplying liquid fuel through a-metering orifice to a main fuel passage for discharge into a mixture conduit, means responsive to intake manifold suction and engine temperature for varying the fuel flow through said orifice to provide a rich fuel mixturefor starting and warming up a cold engine, and temperature controlled means for modifying the suction to provide a relatively lean fuel mixture after the engine has been warmed up, said temperature controlled means comprising .a suction passage leading from said mixture conduit to said suction responsive means, and a suction control valve positioned in said suction passage.

7. In a fuel metering control system for internal combustion engine carburetors having a float bowl for supplying liquid fuel through a metering orifice to a main fuel passage for discharge into a mixture conduit, means responsive to intake manifold suction and engine temperature for varying-the fuel flow through said orifice to provide a rich fuel mixture for starting and Warming up a cold engine, and temperature controlled means for modifying the suction to provide a relatively lean fuel mixture after the engine has been warmed up, said temperature controlled means comprising a suction passage leading from said mixture conduit to said suction responsive means, a suction control valve positioned in said suction passage, and a thermostat to actuate said suction control valve.

8. In a fuel metering control system for internm combustion engine carburetors having a float bowl for supplying liquid fuel through a metering orifice to a main fuel passage for discharge into a mixture conduit, a metering rod for said orifice, a piston supporting said rod and operative responsive to intake manifold suction and engine temperature for varying the fuel flow through said orifice to provide a rich fuel mixture for starting and warming up a cold engine, and temperature controlled means for modifying the suction to provide a relatively lean fuel mixture after the engine has been warmed up. said temperature controlled means comprising a suction passage leading from said mixture conduit to said suction responsive means, a suction control valve positioned in said suction passage, and a thermostat to actuate said suction control valve.

9. In a fuel metering control system for internal combustion engine carburetors having a float bowl for supplying liquid fuel through a metering orifice to a main fuel passage for discharge into a mixture conduit, fuel metering means responsive to intake manifold suction for varying the fuel flow through said orifice, said means comprising a suction passage leading to said mixture conduit, a suction control valve in said suction passage, an unbalanced choke valve to actuate said suction control valve, and temperature responsive means controlling said choke valve to. provide a relatively rich fuel mixture for starting and Warming up a cold engine.

10. In a fuel metering control system for internal combustion engine carburetors having a float bowl for supplying liquid fuel through a metering orifice to a main fuel passage for discharge into a mixture conduit, fuel metering means responsive to intake manifold suction for varying the fuel flow through said orifice, said means comprising a suction passage leading to said mixture conduit, a suction control valve in said suction passage, an unbalanced choke valve to actuate said suction control valve, and temperature responsive means controlling said choke valve to provide a relatively rich fuel mixture for starting and warming up a cold engine, said fuel metering means comprising a suction piston, and a metering rod secured to said piston.

11. In a -fuel metering control system for internal combustion engine carburetors having a main fuel passage, choke and throttle valves, a float bowl for supplying liquid fuel through a metering orifice to .said main fuel passage for discharge into a mixture conduit, a valve to control the flow of fuel through said orifice, means responsive to intake manifold suction to actuate said valve for varying the fuel flow through said orifice, and temperature responsive means controlling said suction responsive means to provide a relatively rich fuel mixture for starting and warming up a cold engine, said suction responsive means comprising a suction passage leading to said mixture conduit, a suction control valve in said suction passage, said temperature responsive means comprising a bimetal strip connected to said suction control valve.

References Cited in the file of this patent UNITED STATES PATENTS 2,203,858 Booty June 11, 1940 10 2,705,484 Jorgensen et a1 Apr. 5, 1955 2,719,706 Winkler Oct. 4, 1955 2,798,704 Winter July 9, 1957