Choke valve assembly

Abstract

A choke valve assembly for the air intake passage of an internal combustion engine employs a shaft mounted off-center with respect to the passage, an actuator connected to turn the shaft in a direction to close the choke valve, a vacuum operated device for turning the shaft in a direction to open the choke valve when the engine starts, and a limiter member connected to limit the extent of opening movement of the choke valve in accordance with the position of the actuator. A spring is operatively interposed between the actuator and the choke valve so that the force of the spring increases as the actuator is moved beyond the position corresponding to the closed position of the choke valve. A cam track on the actuator is engaged by a follower on the limiter member.

Description

This invention relates to internal combustion engines, and is particularly directed to improvements in a choke valve assembly for controlling flow of air through the intake passage of the engine.

Conventional choke valve devices for internal combustion engines commonly employ a vacuum operated device to open the choke valve when the engine starts to run under its own power. In such case, the degree of opening of the choke valve is usually set at a fixed angle. However, it is desirable to have this degree of opening of the choke valve vary in accordance with the ambient temperature.

It is an object of this invention to provide a choke valve assembly in which the choke valve remains closed until the engine starts to run under its own power, and then opens only to an extent previously determined by the position of a choke knob or other operating means.

Another object of this invention is to mount the choke valve on a shaft positioned off-center with respect to the air intake passage, and to close the choke valve by means of a spring so that the spring force increases in accordance with increased movement of the choke knob beyond a position corresponding to closed position of the choke valve.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIG. 1 is a side elevation, partly broken away, showing a preferred embodiment of this invention, the choke valve being shown in the open position.

FIG. 2 is a view similar to FIG. 1, certain parts being removed and separately shown, for clarity of illustration.

FIG. 3 is a view similar to FIG. 1, the control knob being moved to a first position, and the choke valve being shown in closed position.

FIG. 4 is a view similar to FIG. 3, the control knob being moved to a second position, and the choke valve being shown in closed position.

Referring to the drawings, the intake passage 1 for an internal combustion engine, not shown, is provided with a choke valve 2 fixed on a choke shaft 3 mounted to turn so that the choke valve 2 may be moved between the closed position shown in FIG. 3 and the open position shown in FIG. 1. The shaft 3 is positioned to one side of the intake passage 1 so that the choke valve 2 is mounted off-center with respect to said passage. A disk 4 is fixed to the projecting portion of the shaft so that it turns in unison with the choke valve 2. An actuator member 5 is mounted to turn on the shaft 3, and a coil spring 6 is provided between the disk 4 and the actuator member 5 so that the shoulder 4a on the disk 4 is resiliently urged into contact with the shoulder 5a on the actuator member 5. A spring, not shown, acts to move the actuator member 5 in a counterclockwise direction, as shown in the drawings. A choke cable 7 is pivotally connected to the actuator member 5 at 7a and is connected to a manually operable knob 8 by way of a rod 8a.

A vacuum operated device generally designated 9 includes a pipe 10 which is subjected to vacuum presssure in the intake manifold of the engine. The pipe 10 communicates with a vacuum pressure chamber 11 containing a coil compression spring 12 which acts against a flexible diaphragm 13. Suction pressure in the chamber 11 acts to move the diaphragm 13 in a direction to compress the spring 12. A rotary stop element 14 is mounted to turn on the shaft 3 and is pivotally attached to the connecting rod 15 at the pivot 15a. The stop element 14 carries a projecting arm 16. Suction pressure in the chamber 11 serves to tension the connecting rod 15 to move the element 14 in a counterclockwise direction about the shaft 3. The radial shoulder 14a on the element 14 is positioned to engage the shoulder 4a on the disk 4 so that counterclockwise turning movement of the element 14 and arm 16 serves to turn the disk 4 and the shaft 3 and choke valve 2 in the same direction.

A shaft 17 laterally spaced from the choke shaft 3 pivotally supports a limiter arm 18 having a cam follower 18a at its projecting end. This cam follower 18a contacts a cam track 19 provided on the actuator member 5, and is held in contact therewith by means of a spring, not shown. The limiter 18 acts to limit the extent of movement of the arm 16 under tension force of the connecting rod 15. This in turn serves to limit the extent of opening movement of the choke valve 2 from closed position when the knob 8 is retracted to a greater extent than shown in FIG. 3. The greater the extent of retraction of the knob 8 beyond this position, the further the follower 18a moves away from the axis of the choke shaft 3 along the cam track 19.

The disk 4 is also referred to as the first element and the rotary stop element 14 is also referred to as the second element.

In operation, the choke valve 2 is to be left in open position as shown in FIG. 1, when the engine to be started is still warm following previous operation. The manual knob 8 remains in the "off" position. The actuator member 5 rests in the position shown in FIG. 1, under the action of a spring, not shown. The coil spring 6 holds the disk 4 in position with respect to the actuator member 5, and the disk 4 acting through the shaft 3 holds the choke valve 2 in the fully open position. When the engine starts and begins to run on its own power, the suction pressure transmitted through the pipe 10 to chamber 11 causes the diaphragm to move to compress the spring 12 and move the arm 16 to turn in a counterclockwise direction. However, this movement of the stop element 14 and arm 16 does not have any effect on the position of the choke valve 2 because the shoulder 14a on the stop element 14 does not move far enough to contact the shoulder 4a on the disk 4; the stop element 14 and the arm 16 turn freely about the shaft 3.

When the engine is cold, manual knob 8 is pulled to an intermediate position in which the ball 20 engages the detent 21 in the rod 8a, as shown in FIG. 3. This action causes the cable 7 to turn the actuator member 5 about the shaft 3 to the position shown in FIG. 3. The spring 6 causes the disk 4 to move in unison with the actuator member 5, and this brings the choke valve 2 into fully closed position. The follower 18a on the limiter arm 18 remains in engagement with a circular portion of the cam track 19, and the limiter arm 18 thus remains in substantially the same angular position with respect to its supporting shaft 17. The choke valve 2 remains in fully closed position until the engine starts and begins to run on its own power. The vacuum pressure in the chamber 11 then causes the connecting rod 15 to move to the right, thereby swinging the stop element 14 and arm 16 in a counterclockwise direction, by reason of the contact of the shoulder 14a of the element 14 with the shoulder 4a on the disk 4. The arm 16 on the element 14 does not engage the upper end of the limiter arm 18 and therefore there is no effect on the counterclockwise movement of the disk 4 and the choke valve 2, corresponding to the full open position of the choke valve 2. The rush of air in the intake passage 1 applies a force tending to turn the choke valve 2 toward open position, because of the off-center mounting of the choke valve 2 on the shaft 3. The suction pressure in the chamber 11 also tensions the connecting rod 15 to swing the stop element 14 in a counterclockwise direction.

When the engine is cold and the ambient temperature is very cold, the knob 8 is pulled to move the rod 8a to the left beyond the position shown in FIG. 3, and to such a position as shown in FIG. 4. This action causes the cable 7 to move the actuator member 5 in a counterclockwise direction to cause the shoulder 5a on the actuator member 5 to separate from the shoulder 4a on the disk 4, storing energy in the spring 6. The shoulders separate because the choke valve 2 in its closed position prevents further clockwise movement of the disk 4. The follower 18a on the end of the limiter arm 18 lies at a higher elevation. When the engine starts and begins to run under its own power, the suction pressure in the chamber 11 tensions the connecting rod 15, bringing the shoulder 14a on the stop element 14 into engagement with the shoulder 4a on the disk 4. This turns the disk 4 and choke valve 2 until the lever 16 engages the upper end of the limiter arm 18, preventing further counterclockwise movement of the choke valve 2. The choke valve 2 then remains in an intermediate position determined by the position of the manual knob 8. When the knob 8 is returned to the "off" position shown in FIG. 1, the choke valve 2 moves to the fully open position, as described above.

It will be observed that the choke valve 2 remains in fully open position so long as the knob 8 is in the "off" position, as shown in FIG. 1. Moreover, the choke valve moves from fuly closed to an intermediate position as soon as fully engine starts and runs under its own power, the intermediate position depending upon the position of the manual knob 8 beyond the position shown in FIG. 3. The further the knob 8 is moved to the left, as viewed in the drawings, the closer the choke valve 2 remains to fully closed position, after the engine starts and runs under its own power. Also, because the choke valve 2 is eccentrically mounted on the choke shaft so that flow of air tends to move it toward open position, the force of the spring 6 increases as the knob 8 is moved beyond the position corresponding to the closed position of the choke valve 2.

Having fully described our invention, it is to be understood that we are not to be limited to the details herein set forth, but that our invention is of the full scope of the appended claims.

Claims

We claim:

1. In a choke valve assembly for an air intake passage of an internal combustion engine, the combination of: a turnable choke shaft having a choke valve fixed thereto to control flow through said air intake passage, an actuator connected to turn the shaft in a direction to close the choke valve, the actuator being provided with a cam track, means responsive to engine vacuum pressure for turning the shaft in a direction to open the choke valve, and means including a limiter member connected to limit the extent of opening movement of the choke valve in accordance with the position of said actuator, said limiter member having a follower engaging said cam track.

2. The combination set forth in claim 1 in which the choke shaft is mounted off-center with respect to the air intake passage, and in which a spring is operatively positioned between the actuator and the choke shaft, the force of the spring increasing as the actuator is moved beyond the position corresponding to the closed position of the choke valve.

3. In a choke valve assembly for an air intake passage of an internal combustion engine, the combination of: a turnable choke shaft having a choke valve fixed thereto to control flow through said air intake passage, a first element fixed to the shaft, an actuator mounted to turn of the shaft and provided with a cam track, a spring operatively interposed between said first element and said actuator for turning movement, a second element mounted to turn on the shaft and having a projecting arm, a limiter member mounted to turn about an axis laterally spaced from said shaft and having a follower engaging said cam track, means whereby said second element may turn said first element until said projecting arm engages with said limiter member, manual means for turning the actuator in a direction to close the choke valve, and means responsive to engine vacuum pressure for turning said second element in a direction to open the choke valve.

4. In a choke valve assembly for an air intake passage of an internal combustion engine, the combination of: a turnable choke shaft mounted off-center with respect to the air intake passage and having a choke valve fixed thereto to control flow through said passage, a first element fixed to the shaft, an actuator mounted to turn on the shaft and provided with a cam track, a spring operatively interposed between said first element and said actuautor for turning movement, a second element mounted to turn on the shaft and having a projecting arm, a limiter member mounted to turn about an axis laterally spaced from said shaft and having a follower engaging said cam track, means whereby said second element may turn said first element until said projecting arm engages with said limiter member, manual means for turning the actuator in one direction, and means responsive to engine vacuum pressure for turning said second element in the other direction.

5. In a carburetor assembly, the combination of: means forming a passage adapted to supply an air-fuel mixture to an internal combustion engine, a choke valve mounted on a shaft to turn in said passage, a choke actuating member mounted to turn about the axis of the choke shaft, said member having a cam surface thereon, a limiter mounted to turn about an axis spaced from the choke shaft, a follower on the limiter engaging the cam surface, a rotary stop element mounted to turn about the axis of the choke shaft, said rotary stop element having an element engageable with the limiter to limit the extent of opening movement of the choke valve, and a vacuum breaker connected to actuate said rotary stop element.

6. In a carburetor assembly, the combination of: means forming a passage adapted to supply an air-fuel mixture to an internal combustion engine, a choke valve mounted on a shaft to turn in said passage, a choke actuating member mounted to turn about the axis of the choke shaft, said member having a cam surface thereon, a limiter mounted to turn about an axis spaced from the choke shaft, a follower on the limiter engaging the cam surface, a rotary stop element mounted to turn about the axis of the choke shaft, said rotary stop element having an element engageable with the limiter to limit the extent of opening movement of the choke valve, a vacuum breaker connected to actuate said rotary stop element, and means including a follower engaging said cam surface for moving the throttle valve in accordance with movement of said choke actuating member.

7. In a choke valve assembly for an air intake passage of an internal combustion engine, the combination of: a turnable choke shaft having a choke valve fixed thereto to control flow through said passage, means mounting the choke shaft in an off-center position with respect to said passage, a disk element fixed to the choke shaft and provided with a shoulder, an actuator mounted to turn coaxially of the choke shaft and provided with a shoulder, a spring operatively interposed between said disk element and said actuator and acting to maintain said shoulders in contact, a rotary stop element mounted to turn coaxially of the choke shaft and having a shoulder engageable with the shoulder on said disk element to limit the extent of turning movement of said disk element under force of said spring, means responsive to engine vacuum pressure for turning said rotary stop element in a direction corresponding to opening movement of the choke valve, the actuator having a cam track, and a limiter engaging the cam track and positioned to limit turning movement of the rotary stop element in said direction.

8. In a choke valve assembly for an air intake passage of an internal combustion engine, the combination of: a turnable choke shaft having a choke valve fixed thereto to control flow through said passage, means mounting the choke shaft in an off-center position with respect to said passage, a disk element fixed to the choke shaft and provided with a shoulder, an actuator operating to turn said disk element in a direction to close the choke valve and provided with a shoulder, a spring operatively interposed between said disk element and said actuator and acting to maintain said shoulders in contact, a stop element having a shoulder engageable with the shoulder on said disk element to limit the extent of turning movement of said disk element under force of said spring, means responsive to engine vacuum pressure for moving said stop element in a direction corresponding to opening movement of the choke valve, and a limiter connected to limit the extent of movement of the stop element in a direction to open the choke valve in accordance with the position of said actuator.