US2108296A - Automatic choke - Google Patents

Description

Feb. 15, 1938. J E. ROUALET 2,108,296

AUTOMATIC CHOKE Filed May 18, 193] IN VEN TOR.

ANDRE d. E. ROUALET Patented Feb. 15, 1938 UNITED STATES PATENT OFFICE AUTOMATIC CHOKE Andre J. E. Roualet, D Chrysler Corporation, ration of Delaware etroit, Mich., assignor to Detroit, Mich a corpo- Application May 18, 1931, Serial No. 538,133

13 Claims.

5 bustion engine, particularly during starting thereof and during the warming up stages which follow starting.

An internal combustion engine can not always be started when the choke valve is completely l0 closed or at any one predetermined position. The

position at which the choke valve must be set depends upon the temperature ofthe engine at the time it is started. For this reason, fully automatic choke regulating mechanism must be capable of predetermining the closed positions of the choke valve with respect to the temperature of the engine, in addition to gradually opening the choke valve as the temperature rises after the engine is started. The main objects of the invention are to provide carburetor choking apparatus which is fully automatic in its'operation to the extent of requirlng no manual effort or attention in addition to that employed in bringing the conventional e e starting mechanism into operation; to provide means of this kind which holds the choke valve of a carburetor in a predetermined closed position while the starting mechanism 01' an englue is operated; to provide thermostatic mechanism for predetermining the closed positions of the choke valve with respect to the temperature of the engine so as to prevent overloading of the carburetor during starting of the engine at various temperatures; to provide temperature responsive mechanism of this kind whlchalso predetermines the initial degree of opening of the choke valve immediately after operation of the starting mechanism is discontinued following the occurrence of the first explosions; and to provide v regulating means of this character which is adapted to gradually open the choke valve from its initial open position to a full open position during the warming up stage of the engine. I 7 An illustrative embodiment of the invention 46 is shown in the accompanying drawing, in which:

Fig. 1 is a fragmentary elevation. of a. vehicle engine showing my improved choke regulating mechanism, partly in section, and illustrating diagrammatically, its connection with the starting mechanism of the engine.

Fig. 2 is a horizontal section of'the choke yalve regulating mechanism taken ,on the line 2-2 of Fig. 1. v

Fi is a vertical section of the choke valve regulating mechanism showing the relative position of the parts thereof when the circuit of the starting mechanism is closed while the engine is at an elevated temperature.

Fig. 4 is a transverse horizontal section taken on the line 4'4 of Fig. 3.

Fig. 5 is a vertical section taken on the line '5-5 of Fig. 3. I

Fig. 6 is a fragmentary vertical sectional view taken on the line 6-6 of Fig. 2.

In the form shown, the invention is illustrated in connection with 'an internal combustion engine which includes a cylinder head I, an exhaust manifold 2 and an intake manifold 3. Communicating with the intake manifold 3 is an air passage 4 of a carburetor 5 of conventional construction having an air inlet 6 which is provided I with a butterfly type of choke .valve 1. The choke valve is carried on a shaft 8 which is Journaled in apertures in the respectively opposite sides of the air inlet 6 and which is eccentrically located on the choke valve. The suction in the air passage 4 of the carburetor normally I urges the choke valve in a counterclockwise direction toward its open position.

Formed in the choke valve are a plurality of apertures or air passages l0 which provide an auxiliary air inlet to the carburetor. An auxiliary valve including a disc ll having a stem l2 thereon which is slidably mounted in an aperture ii in the choke valve 1, is carried by the latter valve and is provided with a coil spring l4 which bears between one side of the choke valve and a washer IS on the free end of the valve stem. The auxiliary valve is unobstructed and free to open under the control of the carburetor suction when the choke valve 1 is closed. The spring l4 and the apertures III are correspondingly calibrated so as to admit the correct amount of air under the force of the suction which is created in the air passage 4 during the cranking operation of the engine, so as to produce in conjunction with the fuel which is fed into the air passage 4 by the suction therein, a fuel mixture which has suitable explosive properties for efiecting the initial explosions of the engine during cold starting.

The choke valve I is provided with automatic regulating mechanism which includes a casing or housing I6 having side flanges I! by which the housing is rigidly mounted on the cylinder head I of the internal combustion engine by bolts l8. The housing extends downwardly at the side of the cylinder head i and is located directly over the exhaust manifold 2.

Mounted in the casing i6 is a solenoid l9 hav ing one grounded terminal and another terminal 26 which is electrically connected by a conductor 2| with one contact element of a starter switch 22. The starter switch is electrically connected with a battery 23 of which one terminal is grounded at 24 and it may be closed by depression of a starter pedal 25 which simultaneously energizes the solenoid l9 and the starter motor 26.

The armature 21, including a flat plate 28 in which is formed a longitudinal slot 29, is pivotally mounted at 38 upon a bracket 3| which is rigidly secured to an end wall of the casing l6. A spring 30' which bears between the end wall of the casing and the lower side of the armature 21 normally urges the latter about its pivotal axis in a counterclockwise direction. This armature extends over the solenoid l9 and it has an external, downwardly extending arm 32 which extends through a slot 33 in the wall of the casing. The external end of the arm 32 is connected by an adjustable link 34 with a crank arm 35 on the shaft 8 of the choke valve 1. When the solenoid I9 is energized, the armature .21 is rotated in a clockwise direction against the action of the spring 30' so as to turn the choke valve 1 toward a closed position.

The automatic valve regulating apparatus is provided with control mechanism which co-acts with the armature 21 so as to regulate both closing and opening of the choke valve. This mechanism includes a vertically shiftable bar 36 which extends through registering apertures in a reversely bent end portion of a bracket 31 that is mounted in the casing and below the solenoid IS. The bar extends upwardly through the longitudinal slot 29 of the plate 28 of the armature and is normally urged upwardly by a spring 38 which bears between the bracket 31 and a washer 39 which is secured against upward movement on the bar 36 by a pin 40. The upper end of the bar 36 registers with a set screw 4| which is adjustably threaded in the cover 42 of the casing l6 so as to positively limit upward movement of the bar. Formed on the lower end of the bar 36 is a flange 43 in which is adjustably threaded a set screw 44.

The extremity of the adjustable set screw 44 on the bar 36 registers with one extremity of a thermostatic element 45 which preferably includes a coiled bi-metallic member and which is located in the casing l6 in close proximity to abut spot 46 on the exhaust manifold 2. The thermostatic element 45 holds the shiftable bar 36 in various positions against upward movement under the action of the spring 38 so as to predetermine its position with respect to the temperature of the engine. Mounted in the upper end portion of the bar 36 is a pin 46 which extends outwardly beyond the edges of the slot 29 in the plate 28 and limits upward rotation of the armature. When the solenoid I9 is de-energized, the armature 21 rotates in a counterclockwise direction until it engages the pin 46 which is spaced sufficiently from the lowermost position of the plate 28 of the armature to permit an initial, rapid partial opening of the choke valve 1 as soon as operation of the starting system is discontinued after the first explosions of the engine. The degree of initial opening is predetermined with respect to the temperature of the engine by the thermostatic element 45 which predetermines the position of the shiftable bar 38 and pin 46 with respect to the plate 28 of the armature 21. Further opening of the choke valve beyond the initially open position occurs gradually under control of the thermostatic element 45 as the temperature of the engine rises.

In order to properly position the choke valve for starting the engine while it is at various temperatures, it is necessary to interrupt the clockwise rotation of the armature 21 at various positions depending upon the temperature of the engine at the time the solenoid is energized. This is expediently accompanied by the stop lever 41 which is pivotally secured at one end in a. slot 48 in the bar 36 by a pin 49. The stop lever 41 is located in the longitudinal slot 29 in the plate 28 of the armature and it has an enlarged head 50 at its free extremity which is located between the core 5| of the solenoid l9 and a downwardly bent portion of an inclined lip 52 that is integral with the plate 28 of the armature. The enlarged head 50 of the stop lever 41 has a curved periphery which rests at one side upon the core 5| of the solenoid and registers at its other side with the edge of the inclined lip 52. As the pivoted end of the stop lever 41 'is raised and lowered in unison with the shiftable bar 36, the enlarged head 50 is shifted and rocked upon the core 5| of the solenoid so as to bring the extremity of the lip 52 into contact with the periphery of the head at various positions when the solenoid is en ized to close the choke valve at different engine mperatures. Engagement of the extremity of the lip 52 with the enlarged head of the stop lever 41 arrests the downward movement of the armature so as to hold the choke valve in predetermined partially open"-positions which vary in degree in direct proportion to the engine temperature.

In operation, when the engine is extremely cold, the shiftable bar 36 and the stop lever 41 are held in the positions shown in Fig. 1 by the thermostatic element 45 so as to permit the armature to be rotated to its extreme lower position when the solenoid i9 is energized, so as to substantially completely close the choke valve 1. When operation of the starting mechanism is discontinued following the first explosions of the engine, the solenoid I9 is lie-energized and the armature is allowed to rapidly rotate in a counterclockwise direction, under the combined influence of the spring 30' and the suction on the eccentrirotation so as to retain the choke valve 1 in an initial partially open position. Further opening of the valve from the initially open position to a full open position occurs gradually under control of the thermostatic element.

When the engine is at. a predetermined temperature, the shiftable bar 36 and stop lever 41 are held 'by the thermostatic element 45 in the position shown in Fig. 3 wherein the portions of the periphery of the enlarged head 50 which contact with the core 5| of the solenoid and register with the extremity of the inclined lip 52 respectively, are spaced apart sufiiciently to either completely prevent rotation of the armature or to hold it against rotation beyond a predetermined position. In practice, it isfound that complete closing of the choke valve may be allowed during starting under engine temperatures of 65 F., and therefore the contour of the enlarged head 58 of the stop lever is preferably formed so as to prevent complete closing of the choke valve at or above engine temperature of 65. The curvature of the periphery of the enlarged head 50 is also suitably formed so as to predetermine the position at which downward rotation of the armature is interrupted in proportion to the engine temperature during starting above the selected temperature.

In this manner, the carburetor is conditioned said operating lever to produce various predetermined fuel mixtures during starting at specified engine temperatures 7 within a substantially large range, the air factor of the fuel mixture being dependent upon the contour of the periphery of the head 50 of the stop lever and the characteristics of the thermostatic element 45.

Although but one specific embodiment of this invention has herein been shown and described, it will be understood that various changes in the size, shape and arrangement of parts may be made without departing from the spirit of my invention and it is not my intention to limit its scope other than by the terms of the appended claims.

What I claim is:

1. In an internal combustion engine unit comprising a carburetor having a choke valve and having operating means for urging said valve toward a closed position to condition said engine for starting; means for predetermining the opening and closing movements of said valve with respect to the temperature of said engine including variable means having a member constructed and arranged to positively limit closing of said choke valve by said operating means; a member carried by said variable means for regulating opening of said choke valve after actuation of said operating means is discontinued; and a temperature responsive means disposed ad ac nt said engine andd rectly subjected to temperature changes thereof and coacting with said variable means for controlling the position of said memb rs.

2. In an internal combustion engine including starting mechanism and a carburetor having a valve for controlling the admission of air to said carburetor and having means forautomatically mnv ng said valve toward a closed position hen said, engine is started, control means including a variable stop for positively arresting the operation of said valve closing mechanism and adapted to limit closing of said valve thereby at various positions and including an element for regulating the opening of said valve, and a single thermostat for varying the positions of said stop and said element in accordance with the temperature rise of said engine.

I 3. Choke valve operating mechanism including asupport, an operating lever pivotally mounted on said support and pivotally connected with said choke valve, actuating means for rotating so as to move said choke valve toward a closed position, means for urg-, ing said lever in an opposite direction so as to move said choke valve toward a fully open position when said actuating means is inoperative, control apparatus having a member for limiting rotation of said lever by said actuating means at various positions so as to predetermine the position of said. valve with respect to the temperature to which said control apparatus is subjected, an element on said control apparatus for regulating the opening of said choke valve, and a single thermostat for actuating said control apparatus.

4. Choke valve operating mechanism including a support, an operating lever pivotally mounted on said support and connected with said choke valve, actuating means including a'solenoid for rotating said operating lever so as to move said choke valve toward a closed position, a bar shiftably mounted on said support, a stop arm pivotally mounted on said bar including an enlarged head having a curved periphery, the periphery of said head being in registration with said operating lever, yieldable means co-acting with said shiftable bar for normally holding said stop arm in an operative position, and a thermostat element for moving said'bar against the action of said yieldable means so as to vary the limiting position of the periphery of said enlarged head with respect to said lever in proportion to the temperature to which said thermostatic element is subjected.

5. In combination with an internal combustion engine having a, carburetor provided with a choke valve, choke valve operating mechanism including a casing having a compartment provided with an open end adjacent a portion of said engine which is subjected to heat during operation of the latter, an operating lever pivotally mounted in said casing, means for operatively connecting said lever and said choke valve, actuating means for rotating said operating lever so as to move said choke valve toward a closed position, means for urging said choke valve toward a fully open position when said actuating means is inoperative, a temperature responsive device in said compartment adjacent the open end thereof, and a control member movable by said temperature responsive device, having an element thereon provided with a curved periphery engageable by said operating lever for -limiting rotation thereof by said actuating means in one direction so as to predetermine the closed positions of said engine which is subjected to'heat during operation of the latter, an operating lever pivotally mounted in said casing and connected, with said choke valve, actuating means including a solenoid for rotating said operating lever so as to move said choke valve towarda closed position, a bar shiftably mounted in said casing, a .stop arm pivotally mounted on said bar including a head portion having a curved periphery, the periphery of said head being engageable by said operating lever, yieldable means cooperating with said shiftable bar for normally holding said stop arm in an inoperative position, and a thermostat element for moving said bar against the action of said yieldable means so as to vary the limiting position of the periphery of said head with re spect to said lever in proportion to the'temperature'of said engine.

7. In combination with an internal combustion engine having a carburetor provided with a choke valve, choke valve operating mechanism including a casing having a compartment provided with an open end adjacent a portion of said engine which is subjected to'heat during operation of the latter, a lever pivotally mounted in said casing and connected with said choke valve,

'vided with an open end adjacent a portion of said member movable by said temperature responsive means and engageable between a portion of said lever and said actuating means for predetermining the degree to which said valve is closed by operation of said actuating means.

3. In combination with an internal combustion engine having a carburetor provided with a choke valve, choke valve operating mechanism including a casing having a compartment provided with an open end adjacent a portion of said engine which is subjected to heat during operation of the latter, a lever pivotally mounted in said casing and connected with said choke valve, actuating means for rotating said lever in one direction so as to urge said choke valve toward a closed position to condition said engine for starting, resilient means urging said lever in an opposite direction, control -mechanism having a temperature responsive element located in said open-end compartment and having a shiftable member movable by said temperature responsive means andengageable with said lever for predetermining the degree to which said valve is closed by operation of said actuating means, said shiftable member being provided with a stop engageable with said lever for predetermining the degree to which said valve can be opened when said actuating means is inoperative.

9. Choke valve operating mechanism including a support, an operating lever pivotally mounted on said support and connected with said choke valve, actuating means including a solenoid for rotating said operating lever so as to move said choke valve toward a closed position, a bar shiftably mounted on said support, a stop arm pivotally mounted on said bar including an enlarged head having a curved periphery, the periphery of said head being in registration with one side of said operating lever for limiting valve closing movements of said lever, an element on said shiftable bar for regulating valve opening movements of said lever, yieldable means coacting with said shiftable bar for normally urging the latter in one direction, and a temperature responsive device for moving said bar against the action of said yieldable means so as to vary the limiting position of said stop arm with respect to said lever and to bring said valve opening regulating element into operative relation with said lever.

10. Choke valve operating mechanism including a support, an operating lever pivotally mounted on said support and connected with said choke valve, actuatingmeans for rotating said operating lever so as to move said choke valve toward a closed position, a bar shiftably mounted on said support, a stop arm pivotally mounted on said bar including an enlarged head having a curved periphery, the periphery of said head being in registration with said operating lever, yieldable means coacting with said shiftable bar for normally holding said stop arm in an operative position, and a thermostat element for moving said bar against the action of said yieldable means so as to vary the limiting position of the periphery of said enlarged head with respect to said lever in proportion to the temperature to which said thermostatic element is subjected.

11. Choke valve operating mechanism including a support, actuating means including a solenoid mounted on said support and a lever extending adjacent the core of said solenoid, said lever being operatively connected with said choke valve, a bar shiftably mounted on said support, a stop arm pivotally mounted on said bar having a curv ed peripheral portion and extending between a portion of said lever and the core of said solenoid, yieldable means coacting with said shiftable bar for normally holding said stop arm in an operative position, and a thermostat element for moving said bar against the action of said yieldable means so as to vary the limiting position of the periphery of said enlarged head with respect to said lever in proportion to the temperature to which said thermostatic element is subjected.

12'. A device for controlling the choke-valve of an internal combustion engine, comprising an electro-magnet having a pole-piece, a movable armature associated with said electro-magnet and arranged to be moved toward said pole-piece when the magnet is energized, said armature being adapted for connection to the choke-valve to move the choke-valve toward closedp'osition when the armature is moved toward said polerpiece, a temperature-responsive element, a movable stop disposed between said pole-piece and said armature, an operative connection between said stop and said temperature-responsive element whereby said stop will be controlled by said element to vary the extent to which said armature approaches the pole-piece when the magnet is energized, and means operated by said tempera'ture-responsive element for limiting movement of said armature away from said pole piece.

,13. In combination with an internal combustion engine having a carburetor provided with a choke valve and a control device for said valve, mechanism for operating said device comprising a lever, means for operating said lever to close said valve when the engine is cold, a recipro- ,cable member operatively associated with said lever, a thermostat for actuating said reciprocable member, and a cam pivoted to said reciprocable member in the path of movement of a portion of said lever to prevent said valve from closing when the engine is hot.

ANDRE J. E. ROUALET.

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