US3789815A

US3789815A - Temperature responsive control device

Info

Publication number: US3789815A
Application number: US00116008A
Authority: US
Inventors: L Schreiner
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-02-17
Filing date: 1971-02-17
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05

Abstract

A device for controlling the movement of a control member between first and second positions in accordance with a varying temperature condition and a power condition generated by a temperature-power source. The device includes means responsive to the varying temperature condition and the power condition for driving the control member between the first and second positions so that (1) the control member is driven to the first position when no power condition is generated and the temperature condition is below a prescribed level, (2) the control member is driven toward the second position as a function of the temperature condition when the power condition is generated, and (3) the control member is driven to a prescribed intermediate position between the first and second positions when the temperature condition is at or above the prescribed level and the power condition is terminated.

Description

United States Patent [191 Schreiner [451 Feb. 5, 1974 TEMPERATURE RESPONSIVE CONTROL DEVICE Inventor:

Louis W. Schreiner, Palatine, 111.

Charles M. Carter, Northbrook, ll]. a part interest Feb. 17, 1971 Assignee:

Filed:

Appl. No.:

US. Cl 123/119 F, 60/6, 261/39 B Int. Cl. F02m 1/10, F01b 21/00 Field of Search 123/119 F; 60/6, 7; 261/44,

References Cited UNITED STATES PATENTS 7/1930 Gwisdalla 123/119 F 4/1931 123/119 F 11/194] ..123/119 F 2,942,596 6/1960 Carlson 123/1 19 F 2,946,577 7/1960 Dennison et a1. 123/119 F FOREIGN PATENTS OR APPLICATIONS 1,223,427 2/1960 France 123/119 F Primary Examiner-Wendell E. Burns Attorney, Agent, or Firm-Charles M. Carter [5 7] ABSTRACT A device for controlling the movement of a control member between first and second positions in accordance with a varying temperature condition and a power condition generated by a temperature-power source. The device includes means responsive to the varying temperature condition and the power condition for driving the control member between the first and second positions so that (l) the control member is 10 Claims, 5 Drawing Figures PATENTEU FEB INVENTOR LOUIS WSCHREINER BY HTTORN EY TEMPERATURE RESPONSIVE CONTROL DEVICE BACKGROUND OF THE INVENTION This invention pertains to a temperature responsive control device and more specifically to a power choke for an internal combustion engine.

Various automatic chokes for internal combustion engines are known which function as temperature responsive control devices. However, such chokes have not provided adequate control for all conditions. Power chokes constructed in accordance with the present invention provide for adequate control during hot and cold starts.

During cold starts of a choke constructed in accordance with the present invention, the butterfly valve is fully closed when the engine cranks. Once the engine fires and carburetor vacuum is developed, the butterfly valve is opened to a position determined by the engine temperature and thereafter during engine operation the butterfly valve position is determined by the engine temperature.

During hot starts, the butterfly valve is maintained in a prescribed open position when the engine cranks. Once the engine fires and carburetor vacuum is developed the butterfly valve is again opened to a position determined by the engine temperature and thereafter the butterfly valve position is dependent upon the engine temperature.

SUMMARY An object of the present invention is to provide a new and improved temperature responsive control device for controlling the movement of a control member between first and second positions in accordance with a temperature condition and a power condition generated by a temperature-power source so that the control member position is determined by the temperature condition when the power condition is generated. Another object is to provide such a temperature responsive control device wherein the control member is moved to a prescribed intermediate position when the power condition is terminated while the temperature condition is at or above a prescribed level.

A further object of the present invention is to provide a new and improved automatic choke control device for an internal combustion engine. Still another object is to provide such an automatic choke control device wherein, during cold starts, the butterfly valve is fully closed while the engine cranks and is opened to an operating position determined by the engine temperature when the engine starts. A further object is to provide such an automatic choke wherein the butterfly valve is moved between the fully closed position and a fully open position in accordance with the engine temperature during engine operation. An additional object'of the present invention is to provide such an automatic choke control device wherein the butterfly valve is maintained in a prescribed open position during hot starts. A still further object of the present invention is to provide such an automatic choke control device wherein the temperature operating range is adjustable and the hot start temperature is presetable.

A further object of the present inventionis to provide a new and improved automatic choke control device for an internal combustion engine having a carburetor and a choke butterfly valve movable between first and second positions which includes a housing having an inner chamber associated with the engineso that the temperature in the inner chamber is determined by the engine temperature, a power source connected to the butterfly valve and operable to drive the butterfly valve between the first and second positions as a function of engine operation, first means responsive to the temperature in the inner chamber for controlling the operation of the power source so that the butterfly valve position is determined by the engine temperature, and second means responsive to the temperature in the inner chamber attaining a prescribed level and to the butterfly valve attaining a prescribed position for overriding the first means and for preventing the power source from driving the butterfly valve from the prescribed position to the first position when engine operation is terminated while the temperature in .the inner chamber is at or above the prescribed level.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a portion of an internal combustion engine illustrating the application of an auto- I matic choke control device constructed in accordance with the teachings of the present invention;

FIG. 2 is an end elevational view of a first embodiment of an automatic choke control device constructed in accordance withthe teachings of the present invention;

FIG. 3 is aside elevational view of automatic choke control device shown in FIG. 2 taken generally along line 2 2;

FIG. 4 is a fragmentary side elevational view of a portion of the automatic choke control device shown in FIGS. 2 and 3 which is modified to accommodate an air filter; and

FIG. 5 is a cross sectional side elevational view of a second embodiment of an automatic choke control device constructed in accordance with the teachings of the present invention.

DESCRIPTION OF THE INVENTION Referring now to the drawings and more specifically to FIG. 1, a portion of an internal combustion engine is illustrated which includes a carburetor 10 having an air horn 20, the upper end 12 of which is adapted to be fitted to an air filter and a lower end 14 which is connected to an intake manifold 16. The engine also includes an exhaust manifold 17. A butterfly choke valve 18 is mounted within the air horn 20 for pivotal movement about shaft 19.

In accordance with the present invention, a new and improved automatic choke control device 22, which is mounted to the exhaust manifold 17, is provided for controlling the pivotal movement of the butterfly choke valve 18 between a fully closed position and a fully opened position. The automatic choke control device 22 is connected to the butterfly choke valve by a connecting shaft 24and a linkage 26, as is conventional with present automatic choke control devices. Referring now to FIGS. 2 and 3, a first embodiment of an automatic choke control device 22 constructed in accordance with the teachings of the present invention is illustrated in'greater detail. The exemplary choke control device includes a main housing 40 having an inner chamber 42, an outlet port44 and an inlet port 46. The outlet port 44'is connected to the vacuum side of carburetor 10 via tubing 28 as illustrated in FIG. 1. The

inlet port 46 is connected to a heater tube 30 which passes through the exhaust manifold 17. The choke control device 22 also includes a power source 48 which is connected to the butterfly choke valve 18 by the connecting rod 24 and the linkage 26.

In the exemplary arrangement, the power source 48 if in the form of a spring biased diaphragm including a rubber diaphragm member 50, a coil spring 52 and a plunger 54 having a tab 55 secured thereto which is connected to the connecting rod 24. The inner chamber 56 of the power source communicates with the inner chamber 42 of the main housing via an air port (or vent) 58 formed in projection 59 of the housing 40 so that the diaphragm 50 is drawn downward as viewed in FIGS. 2 and 3 when a vacuum is created in the inner chamber 42 by the carburetor. The upper end of the plunger 54 is connected to the top of the diaphragm 50 so that it moves up and down with the diaphragm and the position of the butterfly choke valve 18 is determined by the diaphragm position. When the diaphragm 50 and thus the plunger 54 are in the uppermost position as shown in FIG. 3, the butterfly choke valve 18 will be in a horizontal position as viewed in FIG. 1 so that the air born is closed. That is, the butterfly choke valve will be in the fully closed position. As the diaphragm 50 is drawn downward as viewed in FIG. 3, the plunger 54 is drawn downward therewith causing the connecting rod 24 to be drawn downward as viewed in FIG. 1 so that the butterfly choke valve 18 moves to an open position such as that illustrated in FIG. 1. When the diaphragm 50 is drawn to its bottomed or lower-most position, the butterfly choke valve will be in a vertical position as viewed in FIG. 1 and thus will be in the fully opened position. During this fully open condition, a rubber washer 53 associated with plunger 54 will seat on top of the projection 59 in which the air port 58 is formed so that the air port is closed off and so that strain on the diaphragm is relieved in the face of maximum carburetor vacuum. The washer seating will also function to shut off any leakage that may occur around the plunger bearing positioned within the projection 59.

In the exemplary arrangement, a spring-loaded valve 60 is positioned in the inlet port 46 to control the flow of air therethrough. The spring 61 is adjusted to balance the force on valve 60 due to the vacuum in chamber 42 and causes the valve 60 to be closed in the absence of such vacuum so that the inlet port 46 is closed. As will become apparent, vacuum developed in the inner chamber 42 by the carburetor will cause the valve 60 to open under prescribed conditions so that heated air may be drawn into the inner chamber 42 through the heater tube 30.

In accordance with the present invention, first means are provided for responding to the temperature in the inner chamber 42 for controlling the operation of the power source 48 when the engine is operating so that the butterfly choke valve position is determined by the engine temperature. Additionally, second means are provided for responding to the temperature within the inner chamber 42 attaining a prescribed level and to the butterfly choke valve attaining a prescribed position for overriding the first means and preventing the power source 48 from driving the butterfly choke valve from the prescribed position to the fully closed position when engine operation is terminated and while the temperature within the inner chamber 42 is at or above the prescribed level. In the exemplary arrangement, the first and second means are in the form of portions of a bi-metallic element 62 which is secured to the housing 40 at 64. The bi-metallic element 62 is connected to one end of a control element 66 at 68. The control element 66 is adapted to engage the valve 60 and is connected to the lower end of the plunger 54 at lips 70. The bi-metallic element 62 responds to the temperature within the inner chamber 42 so that the right hand portion 620 as viewed in FIG. 3 moves downward as the temperature becomes colder and moves upward as the temperature becomes warmer. Accordingly, as the temperature within the inner chamber 42 becomes colder the right hand end of the control element 66 is drawn downward as viewed in F IG. 3 to allow for opening of the valve 60 responsive to vacuum being developed within the inner chamber 42. Similarly, as the temperature within the inner chamber warms up, the right hand end of the control element 66 is driven upward by the bi-metallic element 62 to limit or prevent opening of the valve 60. In like manner, as viewed in FIG. 3, the left hand portion 62b of the bi-metallic element 62 moves to the left as the temperature within the inner chamber 42 becomes colder and moves to the right as the temperature becomes warmer. The bimetallic portion 62b is provided with a hook end 72 which is adapted to engage or hook the lower end 70 of the plunger 54 under prescribed hot start conditions so that the plunger is held by the hook end 72 and is prevented from moving upward as long as such conditions exist.

At this point, it may be helpful to provide a brief description of the operation of the automatic choke control device shown in FIGS. 2 and 3 as the engine is started and operates. Initially, it will be assumed that the idle engine is cold so that

portions

62a and 62b of the bi-metallic element are in their cold state positions respectively toward the bottom of the housing 40 and toward the left hand end of the housing as viewed in FIG. 3. Under these conditions, the control element 66 will have its right hand end positioned toward the bottom of the housing 40 and the plunger 54 and diaphragm 50 will be in the upper position as shown in FIG. 3. When the engine is started under these conditions, the vacuum created by the carburetor causes the valve 60 to open so that air is drawn into the inner chamber 42 through inlet port 46 from the heater tube 30. The air drawn into the inner chamber 42 heats up as the engine heats up so that bi-metallic element 62 likewise heats up. During such heat-up, the portion 62a of the bi-metallic element moves upward forcing the right hand end of the control element 66 upward so that the valve 60 is likewise driven upward toward the closed position. As the valve 60 begins to close under these conditions, the vacuum begins to build up within the inner chamber 42 and thus within the inner chamber 56 of the diaphragm assembly. This causes the diaphragm 50 to be drawn downwardly and thus causes the plunger 54 to be currently drawn downwardly. Responsive to downward movement of the plunger 54, the butterfly choke valve 18 is opened correspondingly. As the plunger 54 moves downward the left hand end of the control element 66 is driven downward therewith causing the valve 60 to open. The diaphragm 50 and the plunger 54 will move downward until the valve 60 is opened sufficiently to equalize the pressure within the

inner chambers

42 and 56 so that the vacuum force on the diaphragm 50 is counterbalanced by the force of the spring 52. As the bi-metallic element 62 becomes progressively hotter responsive to progressively hotter air being drawn into the inner chamber 42 the balance point of the diaphragm assembly moves progressively lower and thus the butterfly choke valve is opened progressively. Thus it will be apparent that the position of the butterfly choke valve is determined by the temperature of the air drawn into the inner chamber 42 and thus is dependent upon the temperature within the engine exhaust manifold 17.

The portion 62b of the bi-metallic element 62 is provided to allow for hot starts of the engine. This is accomplished by limiting operation of the automatic choke control device when the engine is hot (when the manifold temperature is hot) and the bi-metallic element 62 is in its heated up condition. When the plunger 64 has been drawn downward a sufflcient distance and a prescribed temperature condition exists within the inner chamber 42 to cause the portion 62b of the bimetallic element to have moved sufficiently to the right as viewed in FIG. 3, the hooked end 72 of portion 62b will be positioned above the lips 70 of the plunger 54 so that, when the engine is turned off and carburetor vacuum is no longer generated, the plunger is driven upward by the spring 52 and the hooked end 72 will engage the lips 70 to hold the plunger in a prescribed intermediate position. Under these conditions, the butterfly choke valve 18 is held in a prescribed intermediate open position rather then returning to the fully closed cold start position. It is desireable for the butterfly choke valve to be maintained in this intermediate position to allow for starting of a hot engine.

As the engine remains idle over a period of time, the temperature within the inner chamber 42 will cool down, representing engine cooling, so that the bimetallic element portion 62b moves to the left as viewed in FIG. 3. At a prescribed temperature level the portion 62b will have moved sufficiently to the left to release the plunger 54 so that the diaphragm assembly can return to the cold start condition as illustrated in FIG. 3. At such time, the automatic choke control device is again in condition for a cold engine start and will function as described above.

Further, in accordance with the present invention, means are provided for adjusting the operating conditions of the automatic choke control device. Referring to FIG. 3, a threaded operating adjustment element 74 is provided for presetting the proper cold run position of portion 62a of the bi-metallic element 62. That is, element 74 allows for presetting the bottomed position of portion 62a so that, upon engine starting, a desired vacuum is developed in

inner chambers

42 and 56 causing the plunger 54 and thus the butterfly valve 18 to be moved to the desired cold run position for the engine. Additionally, a cold run limit adjustment threaded element 76 is provided for the purpose of limiting the cold run position of portion 62 a responsive to adjustment of the operating adjustment threaded element 74. Without the cold run limit adjustment, in extremely cold conditions, the bi-metal 62a could be preset so that the butterfly valve would be closed more than desired for cold running conditions causing engine flooding. A hot start adjustment threaded control element 78 is provided for presetting the temperature at which the hooked upper end 72 of portion 62b of the bimetallic element will be positioned to engage the lips of the plunger 54.

Referring to FIG. 4 a modified portion of the automatic choke control device 22 shown in FIGS. 2 and 3 is illustrated. In this modified arrangement, the inlet port 46 is adapted to admit air directly from the atmosphere rather than being connected to the manifold heater tube 30 as shown in FIG. I. With this arrangement, an air filter material may be provided for filtering the air admitted through the inlet 46. With this arrangement, the engine heat is conducted to the inner chamber 42 through the housing 40 which is mounted on the engine, as opposed to having hot air drawn into the inner chamber from the manifold heater tube 30. This arrangement is satisfactory as long as sufficient conductive path is provided between the engine and the automatic choke control device.

Referring to FIG. 5, a second embodiment of an automatic choke control device 122 constructed in accordance with the teachings of the present invention is illustrated. This embodiment is similar to the embodiment shown in FIGS. 2 and 3 with the numbering elements being increased by 100. However, port 146 is an outlet port which is connected to the carburetor vacuum side and no inlet port is provided. Additionally, in this arrangement, the bi-metallic element is split into two separate elements 162a and 16212. Element l62b functions as did portion 62b of bi-metallic element 62, whereas element 162a has a reverse action to that of portion 62a of bi-metallic element 62 so that it moves upward as the temperature within the inner chamber 142 becomes colder and it moves downward as the temperature within the inner chamber 142 becomes warmer. Further, spring 161 associated with valve 160 has a reverse action to that of spring 61 so that the valve 160 is thereby urged open. A small bleeder port may be provided in the housing to reduce stringent requirements on the valve 160. Adjusting element 176 allows for presetting the valve 160 to a prescribed open, cold run position.

For the purpose of clarifying the operational differences between the embodiments of FIGS. 3 and 5, a

brief description of the operation of the automatic.

choke control device 122 will be set forth. In this em bodiment the tab 155 of plunger 154 is similarly connected to the butterfly valve 18 so that the butterfly valve position is dependent upon the position of plunger 154. During cold start engine conditions, the bi-metallic element 162a is in its uppermost position as limited by the cold run adjusting element 176 causing the right hand end of the control element 166 to be in its uppermost position so that the valve 160 is open to the cold run position. As the engine starts, vacuum is generated in the inner chamber 1142 by the carburetor causing the diaphragm assembly 1148 to attain a desired position so that the butterfly choke valve 18 attains the desired cold run position. As the engine heats up, the heat therefrom is conducted to the housing causing the temperature in the inner chamber 142 to heat up concurrently therewith. Responsive thereto, the bi metallic element 162a moves downward allowing the spring 161 to force the valve 160 open further and thus 7 allowing the vacuum within the inner housing 142, as well as within chamber 156 of the diaphragm assembly through port 158, to increase. This causes the diaphragm and the plunger 154 to be drawn downward so that the butterfly valve 18 is opened correspondingly. As the plunger 154 is drawn downward, the right hand end of the control element 166 is pivoted upward causing the valve 160 to close correspondingly. The diaphragm assembly will move downward until the valve 160 has been closed sufficiently to adjust the pressure within the chamber 156 so that the vacuum force on the diaphragm 150 is counterbalanced by the spring force of the spring 152. As the bi-rnetallic element 162a becomes progressively hotter responsive to increased engine temperature, the balance point of the plunger assembly moves progressively lower and the butterfly choke valve is opened progressively. Accordingly, the butterfly choke valve position is determined by the position of the bi-metallic element 162a which in turn is dependent upon the temperature within the chamber 142 and thus is dependent upon the engine temperature.

The bi-metallic element 162b functions as the bimetallic element 62b described above herein to allow for hot starts and the operation thereof will therefore not be set forth. Additionally, a hot start adjustment threaded element 178 and an operating adjustment threaded element 174 have been provided to allow for presetting of the hot start temperature and presetting of the desired operating conditions for the automatic choke.

In actual practice, the vacuum produced by the carburetor is reduced by a factor of about 10 to 1 under maximum acceleration. With the exemplary automatic choke control devices, the butterfly choke valve will tend to close under maximum acceleration. The amount of this closure can be controlled in the design of the exemplary automatic choke control devices to provide a desired richer fuel mixture for such maximum acceleration. Since in actual practice the vacuum generated drops to about one pound per square inch during maximum acceleration, this becomes a limiting factor around which the exemplary automatic choke control devices must be constructed.

There are conditions under which more driving force is desirable than is attainable if the butterfly valve is allowed to close, such as, ifa positive drive to the fast idle cam of the engine is required. Such a positive drive system has an advantage in that, with such a system, it is not necessary to step on the accelerator before starting to release the fast idle cam and to let the choke close, as is now necessary in conventional systems. With the present invention, a version of fast idle cam arrangement can be provided that will allow the choke to close even if the accelerator is not depressed before starting. However, every external force and friction added to the system degrades the accuracy of the choke opening.

There are two ways to allow for use of more driving force which avoids the problem of the choke closing too much during acceleration. The first is to provide a spring-ratchet mechanism on the choke shaft plunger or linkage 24 that allows the choke only to proceed in the open direction. Any tendency to close due to heavy' acceleration would be checked by the ratchet. This ratchet-spring mechanism could be linked to the throttle and disengage whenever the throttle is released so that when the car is stopped the choke can return to the closed position. Another system would include a check valve in the vacuum line so that, whenever the vacuum falls below a certain level, the valve closes to retain the high vacuum in the choke drive assembly and the diaphragm so that the choke is retained in its last high vacuum position. Since such systems do not constitute a portion of the present invention, they have not been illustrated herein.

in the exemplary automatic choke control devices, the force generated due to a given vacuum is constant regardless of the position of the diaphragm assembly. Accordingly, a constant force return spring within the diaphragm assembly, while not necessary, may be desirable. In the disclosed arrangements, the spring force is not constant but is proportional to the linear displacement of the spring. This means that the return spring force is proportionally less when the spring is fully extended. A linear force spring action can readily be obtained by using a cam spring arrangement on the choke shaft or linkage 24 and eliminating the internal spring. Such a cam arrangement could be used to allow for use of a cable drive system and thus to allow for more flexibility in the location of the automatic choke control device. The use of the spring return on the choke shaft also has an advantage in that it removes all backlash from the linkage arrangement. Again, this is not part of the invention and has not been illustrated herein.

I claim:

1. In a device for controlling a desired operation in accordance with a varying temperature condition and a power condition generated by a temperature-power source, the combination which comprises a control member movable between first and second positions, and means responsive to said temperature condition and said power condition for driving the control member between said first and second positions so that (l) the control member is driven to said first position independent of said temperature condition when no power condition is generated and said temperature condition is below a first prescribed level, (2) the control member is moved toward said second position as a direct function of said temperature condition when said power condition is generated and when said temperature condition is above a second prescribed level, and (3) the control member is moved to an intermediate position between said first and second positions when said temperature condition is at or above said first prescribed level and said power condition is terminated.

2. In a device for controlling a desired operation in accordance with a varying temperature condition and a power condition generated by a temperaturepower source, the combination which comprises a control member movable between first and second positions, drive means connected to the control member and operable to drive the control member between said first and second positions when said power condition is generated, the drive means including biasing means for driving the control member toward said first position independent of said temperature condition when no power condition is generated, first control means responsive to said temperature condition for overcoming said biasing means and controlling the operation of the drive means so that the control member is driven from said first position toward said second position as a direct function of said temperature condition when said power condition is generated and when said temperature condition is above a first prescribed level, and second control means responsive to said temperature condition attaining or exceeding a second prescribed level.

and to the control member being within a prescribed range between said first and second positions for overriding the biasing means when said power condition is terminated and preventing the biasing means from driving the control member to the first position during the existence of said temperature condition at or above said second prescribed level.

3. The control device of claim 2 wherein adjustable means are provided for pre-setting the temperature condition operating range of said first control means.

4. The control device of claim 2 wherein adjustable means are provided for pre-setting said prescribed level temperature condition at which the second control means overrides the biasing means.

5. The control device of claim 2 wherein a main housing is provided having an inner chamber and an outlet communicating with the inner chamber and being associated with said temperature source so that the temperature in the inner chamber is determined by said temperature condition generated by said tempera- I ture source, wherein the first and second control means are located within said housing and are directly responsive to the inner chamber temperature, and wherein the drive means includes a spring biased diaphragm device associated with the inner chamber and a source of vacuum connected to the outlet.

6. The control device of claim 5 wherein the first and second control means include bi-metallic elements mounted within the inner chamber.

7. In an automatic choke control device for an internal combustion engine having a carburetor and a choke butterfly valve movable between first and second positions, the combination which comprises a housing having an inner chamber associated with the engine so that the temperature in the inner chamber is determined by the engine temperature, a drive system connected to the choke valve and operable to drive the choke valve between said first and second positions, the drive system including means for biasing the choke valve toward said first position when the engine is not operating, first means responsive to the temperature in the inner chamber for controlling the operation of the drive system so that the choke valve is driven from said first position toward said second position as a function of said temperature when the engine is operational, and second means responsive to the temperature in the inner chamber attaining a prescribed level and to the choke valve attaining a prescribed position for overriding the drive system biasing means when engine operation is terminated and preventing the drive system from driving the choke valve from the prescribed position to the first position during the existence of said prescribed level temperature within the inner chamber.

8. The control device of claim 7 wherein adjustable means are provided for pre-setting the temperature operating range of said first means.

9. The control device of claim 7 wherein adjustable means are provided for pre-setting said prescribed temperature at which the second means overrides the power source biasing action.

10. The control device of claim 7 wherein the housing includes an outlet communicating with the inner chamber which is connected to the carburetor and the carburetor provides a source of vacuum, wherein the drive system includes a spring biased, movable diaphragm connected to the choke valve which communicates with the inner chamber and the vacuum created by the carburetor, the diaphragm biasing the choke valve to the first position when carburetor vacuum is not provided, wherein the first means includes a bimetallic element mounted within the inner chamber which controls the vacuum created in the inner chamber by the carburetor in accordance with the inner chamber temperature whereby the diaphragm is moved to a position determined by the existing temperature level in the inner chamber, and wherein the second means includes a bi-metallic element mounted within the inner chamber which overrides the spring biasing of the diaphragm and retains the choke valve in the prescribed position during existence of said prescribed level temperature within the inner chamber when carburetor vacuum is not provided.

Claims

1. In a device for controlling a desired operation in accordance with a varying temperature condition and a power condition generated by a temperature-power source, the combination which comprises a control member movable between first and second positions, and means responsive to said temperature condition and said power condition for driving the control member between said first and second positions so that (1) the control member is driven to said first position independent of said temperature condition when no power condition is generated and said temperature condition is below a first prescribed level, (2) the control member is moved toward said second position as a direct function of said temperature condition when said power condition is generated and when said temperature condition is above a second prescribed level, and (3) the control member is moved to an intermediate position between said first and second positions when said temperature condition is at or above said first prescribed level and said power condition is terminated.

2. In a device for controlling a desired operation in accordance with a varying temperature condition and a power condition generated by a temperature-poweR source, the combination which comprises a control member movable between first and second positions, drive means connected to the control member and operable to drive the control member between said first and second positions when said power condition is generated, the drive means including biasing means for driving the control member toward said first position independent of said temperature condition when no power condition is generated, first control means responsive to said temperature condition for overcoming said biasing means and controlling the operation of the drive means so that the control member is driven from said first position toward said second position as a direct function of said temperature condition when said power condition is generated and when said temperature condition is above a first prescribed level, and second control means responsive to said temperature condition attaining or exceeding a second prescribed level and to the control member being within a prescribed range between said first and second positions for overriding the biasing means when said power condition is terminated and preventing the biasing means from driving the control member to the first position during the existence of said temperature condition at or above said second prescribed level.

5. The control device of claim 2 wherein a main housing is provided having an inner chamber and an outlet communicating with the inner chamber and being associated with said temperature source so that the temperature in the inner chamber is determined by said temperature condition generated by said temperature source, wherein the first and second control means are located within said housing and are directly responsive to the inner chamber temperature, and wherein the drive means includes a spring biased diaphragm device associated with the inner chamber and a source of vacuum connected to the outlet.

10. The Control device of claim 7 wherein the housing includes an outlet communicating with the inner chamber which is connected to the carburetor and the carburetor provides a source of vacuum, wherein the drive system includes a spring biased, movable diaphragm connected to the choke valve which communicates with the inner chamber and the vacuum created by the carburetor, the diaphragm biasing the choke valve to the first position when carburetor vacuum is not provided, wherein the first means includes a bi-metallic element mounted within the inner chamber which controls the vacuum created in the inner chamber by the carburetor in accordance with the inner chamber temperature whereby the diaphragm is moved to a position determined by the existing temperature level in the inner chamber, and wherein the second means includes a bi-metallic element mounted within the inner chamber which overrides the spring biasing of the diaphragm and retains the choke valve in the prescribed position during existence of said prescribed level temperature within the inner chamber when carburetor vacuum is not provided.