US2624325A

US2624325A - Carburetor control mechanism

Info

Publication number: US2624325A
Application number: US171626A
Authority: US
Inventors: Guy C Fricke; David J Schaffer
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1950-07-01
Filing date: 1950-07-01
Publication date: 1953-01-06
Anticipated expiration: 1970-01-06

Description

Jan. 6, 1953 G. c. FRICKE ET AL 2,624,325

CARBURETOR CONTROL MECHANISM v Filed July 1, 1950 2 swans-swam 1 M INVENTOR. 50 60) c. F/P/CA:

34 04 W0 J 56%4/75 4 BY Jan. 6, 1953 G. c. FRICKE ET AL 2,624,325

CARBURETOR CONTROL MECHANISM Filed July 1 1950 2 SHEETS-SHEET 2 INVENTOR. 60) c. PIP/6K5 By any/0 swarm? WMW A /mm) Patented Jan. 6, 1953 CARBURETOR CONTROL MECHANISM Guy 0. Fricke and David J. Schaifer, Detroit,

Mich, assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application July 1, 1950,.Serial No. 171,626

'9 Claims.

The present invention relatesto a control'for anengine, and more particularly to an automatic choke control for a carburetor of an internal combustion engine.

One of the principal objects of the present invention is to provide .a fuel enrichment device for. aninternal combustion engine which varies the fuel-air ratio in accordance with variations in the temperature of the cooling fluid of the engine.

Another .object'of the invention is to provide a control for the :choke valve of a carburetor which .is responsive to manifold vacuumand to variations .in .the .temperature of the liquid in the cooling system of the engine.

Another object is to provide a choke control device for an engine which is readily responsive to a temperature of some part of the engine remote from said device.

A further object is to provide a choke control device which varies the fuel-air ratio in accordance with the engine requirements.

Additional objects and advantages of the present invention will become apparent from the following description and accompanying drawings, wherein:

Figure 1 is a side elevation of a multiple cylinder internal combustion engine showing schematically certain elements of the present invention;

Figure 2 is a vertical cross-sectional view of our choke control device;

Figure 3 is a sectional view of our control device taken on line 33 of Figure 2;

Figure 4 is a sectional view of the control device taken on line 4-4 of Figure 3;

Figure 5 is-a sectional view of a modified form of our invention; and

Figure 6 is asectional view'of a'temperature responsiveswitch for our choke control device.

:Referring -more specifically .to the drawings, and to Figure .1 in particular, wherein a multiplecylinder water 20001601 internal combustion engine .is shown, numeral 4 ii designates a cylinder block, [2 acylinderhead, M an intakeman-ifold, l6 a'carburetor, 18 an air cleaner mountedon saidrcarburetor, and :20 our choke-control device .mounted in operative position on the air horn of the carburetor and-connected byan electrical circuit with a battery 22, an ignitionswitch 24 and a thermostatically controlled switch unit 26 mounted on cylinder .head !2. For the purpose of this description, the engine, including the carburetor, may be considered conventionalin construction and operation.

The choke control mechanism is encased in a housing 30 secured to the carburetor air horn 32 adjacent one end of the choke valve shaft 36 on which choke valve 36 is mounted in the carburetor induction passage 33, said choke valve preferably being of the unbalanced pressure responsive type or having a poppet valve adapted to permit an increase in air flow as soon as the engine begins to fire. Shaft 34 extends into the housing and is rotated in the choke opening direction by a vacuum responsive piston 40 connected to said shaft by a rod 42 and a lever 44 rigidly mounted on one end of said shaft. Piston 4D 'is'adapted to reciprocate in a cylinder 46 in response to'manifold vacuum transmitted to said cylinder through conduits it and 50 and a port 52 from the induction passage on the engine side of the throttle valve. The degree of manifold vacuum required to actuate the choke valve is partially controlled by an air bleed passage'54 extending longitudinally through piston in and connecting cylinder 46 with the internal portion of housing 30, which in turn is vented to the atmosphere through port 56 in cover 58.

The choke Valve is held closed during engine cranking and is urged towards closed position during "the warming-up period by a solenoid 6i] actingthrough a lever 62, a coil spring 64 and. lever 44, said spring being mounted on the end of choke shaft 34 and connected at one end to lever44 and at the other end to lever 62 to form a'resilientlinkage between the choke valve and solenoid 60. Lever 62 is pivoted at one end on a pin 66 secured in the wall of housing 30 and is preferably constructed of soft steel with a thin plate of copper on the lower side at the point of contact between the lever and the solenoid core 68. .Lead .10 connects the solenoid with thermostatic switch 26 and lead i2 connects the solenoid with any suitable ground, such as the main body or the airhorn of the carburetor.

The thermostatic switch unit 26, shown in detail in Figure 6, is in series with the ignition switchand is adapted to control the choke unit on carburetor IS in response to changes in the temperature 'of the engine cooling liquid. The switchis contained in a-cap at of plastic or other nonconducting material and consists of a fixed contact 82 mounted on stem 84 which is secured in the side wall of said cap, and a movable contact 86 mounted on a leaf spring element 88 which is secured by screws E39 and 92 to the inside wall of the cap opposite stem 84, contact 82 being connected by a lead 94 with the ignition switch 24and battery 22, and contact being connected by lead Hi with solenoid 66. The base it of the switch unit is adapted to be secured to the cylinder head of the engine, preferably threaded into a hole therein, and contains a chamber I02 filled with a thermo-expansible material, such as hydrocarbon and copper. A yieldable diaphragm I04 forms the upper wall of chamber I02 and is operatively connected to switch element 88 by a shaft I06 abutting against the upper side of said diaphragm and a stem I08 urged in the direction to permit the switch to close by a coil spring I I9 reacting between a fixed sleeve H2 and a flange II 4 on the lower end of the stem. The upper end of stem I08 is insulated from element 88 by a plastic cap H6. As the engine cooling liquid becomes warm after the engine starts, the heat is transmitted to the thermo-expansible material in chamber I02 which urges diaphragm I04 upwardly, forcing stem I08 to move contact 86 on element 88 away from contact 82, thus interrupting the current from battery 22 to solenoid 60.

In the starting operation of a cold engine, turning on of the ignition switch 24 completes the circuit for the choke unit on the carburetor in that switch unit 26 is always closed when the engine is cold. The solenoid 00, which is then energized, pulls lever 62 to the right, as shown in Figure 3, rotating spring 64 and the choke shaft 34 in the clockwise direction to close the choke valve for starting. As soon as the engine begins to fire, the air flow in the induction passage 38 of the carburetor causes the choke valve (if the valve is of the unbalanced type) to open slightly against the force of spring 64 to provide sufficient air for the operation of the engine before the manifold vacuum has increased sufiiciently to operate piston 40. When the throttle valve is moved toward closed position and the manifold vacuum has, as a result, increased substantially, piston 40 moves downward in cylinder 26, urging the choke valve in the opening direction in opposition to the yieldable force applied by solenoid 60 through spring 64, The degree to which the choke valve will be opened by piston 40 depends upon the size of port 52 relative to passage 54, upon the strength of spring 64, and upon the degree of manifold vacuum. The first two factors can be adjusted to suit requirements. If the throttle valve is-again opened to the point where the manifold vacuum can no longer hold piston 40 down in opposition to the solenoid, the choke valve moves toward closed position and provides additional fuel enrichment for engine acceleration. As the air flow increases with acceleration, the unbalanced valve partially opens to provide the air required for the higher speed. When the cooling liquid has reached a predetermined temperature, thermostatic switch 26 opens the choke circuit, de-enerizing solenoid 60 and permitting the choke valve to move to wide open position for normal engine operation.

In Figure 5, a modification of our choke control device is shown wherein a solenoid I20 and a vacuum piston I22 are on opposite sides of lever 44. The solenoid 120 actuates a metallic piston I24 which is connected to lever 44 by a coil spring I26. Piston I22 is connected to lever 44 by a rod I28. The cylinder 630 in which piston I 22 reciprocates is connected to the induction passage through a port I32 and conduits similar to conduits 48 and 59 shown in Figures 1 and 2. The operation of the choke control device employs an electrical circuit and a thermostatic switch similar to that shown in Figures 1 and 6.

Although thermostatic switch 26 is shown mounted on the engine cylinder head, it may be mounted at any other suitable point in the cooling system of the engine or at some other point on the engine apart from the cooling system, as for example the exhaust manifold, which will indicate the operating temperatures of the engine.

The thermostatic switch may be of the design shown in Figure 6 or any other suitable design. Other modifications may be made in our choke control device to suit requirements without departing from the scope of the present invention.

We claim:

l. A control for an engine carburetor having a choke valve and a shaft for said valve, comprising a lever on said shaft, a solenoid for urging said valve toward closed position, a member actuated by said solenoid, a yieldable means connecting said member to said lever, a vacuum responsive means connected to said lever for urging said valve in the opening direction, a circuit for said solenoid, and a means responsive to some engine temperature for controlling the current through said circuit.

2. A control device for the choke valve of an engine carburetor, comprising a solenoid, a yieldable linkage operatively connected to said valve and adapted to be actuated by said solenoid in the direction to close said valve, and a vacuum responsive means connected to said valve for urging said valve in the opening direction on an increase of manifold vacuum.

3. A control device for the choke valve of an engine carburetor, comprising a solenoid, a resilient linkage, operatively connected to said valve and adapted to be actuated by said solenoid in the direction to close said valve, a vacuum responsive means connected to said valve for urging said valve in the opening direction on an increase of manifold vacuum, a circuit for said solenoid, and a switch means responsive to some engine temperature for controlling the current through said circuit.

4. A control device for the choke valve of a carburetor for a liquid cooled engine, comprising a solenoid, a yieldable linkage operatively connected to said valve and adapted to be actuated by said solenoid in the direction to close said valve, a vacuum responsive means connected to said valve for urging said valve in the opening direction on an increase of manifold vacuum, a circuit for said solenoid, and a switch means responsive to the temperature of the coolingliquid for controlling the current through said circuit.

5. A fuel enrichment device for an internal combustion engine having an induction passage and a carburetor with a throttle valve, a choke valve and a shaft therefor, comprising a lever secured to said shaft, a solenoid, a pivoted lever actuated by said solenoid, a yieldable means connecting said first mentioned lever with said second mentioned lever, and a chamber connected to the induction passage on the engine side of the throttle valve and having a movable wall connected to said first mentioned lever.

6. A fuel enrichment device for an internal combustion engine having an induction passage and a carburetor with a throttle valve, a choke valve and a shaft therefor, comprising a lever secured to said shaft, a solenoid, a pivoted lever actuated by said solenoid, a resilient means functionally interposed between said levers, a chamber connected to the induction passage on the engine side of the throttle valve and having a movable wall, a rod connecting said wall with said first mentioned lever, and a circuit for energizing said solenoid.

'I. A fuel enrichment device for an internal combustion engine having an induction passage and a carburetor With a throttle valve, a. choke valve and a shaft therefor, comprising a lever secured to said shaft, a solenoid, a pivoted lever actuated by said solenoid, a spring connecting said first mentioned lever with said second mentioned lever, a cylinder connected to the induction passage on the engine side of the throttle valve, a piston in said cylinder connected to said first mentioned lever, a circuit for said solenoid, and a means responsive to some engine temperature for controlling the current through said circuit.

8. A fuel enrichment device for an internal combustion engine having a carburetor with a choke valve and a shaft therefor, comprising 'a lever secured to said shaft, a solenoid, a pivoted lever actuated by said solenoid, a yieldable means functionally interposed between said levers, a chamber having a movable wall adapted to be subjected to manifold vacuum, a rod connecting said wall with said first mentioned lever, and a thermo-statically controlled switch responsive to an engine temperature for controlling said solenoid.

9. A fuel enrichment device for a liquid cooled 25 internal combustion engine having an induction passage and a carburetor with "a throttle valve, a choke valve, and a shaft therefor, comprising a lever secured to said shaft, a solenoid, a pivoted lever actuated by said solenoid, a spring connecting said first mentioned lever with said second mentioned lever, a cylinder connected to the induction passage on the engine side of the throttle valve, a piston in said cylinder connected to said first mentioned lever, a circuit for energizing said solenoid, and a thermostatically controlled switch in said circuit responsive to the temperature of the cooling liquid of the engine.

GUY C. FRICKE.

DAVID J. SCI-IAFFER.

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

UNITED STATES PATENTS Number Name Date 1,605,165 Brotz Nov. 2, 1926 1,913,131 Sisson June 6, 1933 2,071,633 Hunt Feb. 23, 1937 2,158,424 Hunt May 16, 1939 2,377,248 Langhaar May 29, 1945