Actuator device
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an actuator device for use with an engine-idle control system of and automobile provided with an air-conditioner and, more particularly, to a vacuum controlled throttle positioning actuator having an improved mechanism for adjusting the stroke of operating plunger in association with throttle valve opening lever of an internal combustion engine. 
     2. Description of the Prior Art 
     In an automobile equipped with an air-conditioner compressor driven by internal combustion engine, it has been proposed that, under idling conditions of the engine, the opening degree of the throttle valve is slightly increased to provide the engine with a larger amount of air-fuel mixture when the air-conditioner compressor starts to run. It has been required to increase the engine power to prevent stalling of the engine under such loaded idling condition. A throttle valve operating mechanism of this general type includes a vacuum controlled throttle positioning actuator as found in U.S. Pat. No. 4,060,063 granted Nov. 29, 1977. Such conventional actuator does not include a mechanism for adjusting the stroke of operating plunger to maintain a predetermined increased opening degree of the throttle valve, so that it is difficult to reliably maintain a desirable opening degree of the throttle valve. On the other hand, actuators having an adjusting mechanism threaded through rear case portion of the actuator are shown, for example, in U.S. Pat. No. 4,137,876 granted on Feb. 6, 1979 and U.S. Pat. No. 3,547,088 granted on Dec. 15, 1970. Such conventional actuators are equipped with an adjustable stop for limiting stroke of the diaphragm. The adjustable stop is threaded through the housing of the vacuum chamber positioned behind the operating plunger, so that such stop is not applied to the actuator having a vacuum control such as solenoid valve provided in the vacuum chamber. 
     In a conventional actuator having an adjustable stop connected to the plunger, it has been proposed to use a double nut, however, it is difficult to adjustably move the double nut since such requires the use of two wrenches. 
     SUMMARY OF THE INVENTION 
     It is, therefore, a principal object of the present invention to provide an improved actuator device which obviates the above noted conventional disadvantages. 
     It is another object of the present invention to provide an improved actuator device wherein adjustment of the stroke of the plunger can be reliably achieved by easy manual operation without the use of a tool. 
     It is a further object of the present invention to provide an improved actuator device which is simple in construction, low in cost, and reliably adjustable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views and wherein: 
     FIG. 1 is a vertical cross sectional view showing an actuator device embodying the inventive concept of the present invention; 
     FIG. 2 is the enlarged vertical cross sectional view of an adjusting member shown in FIG. 1; and, 
     FIG. 3 is a left side view of FIG. 2. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, there is shown the structure of the actuator device in accordance with the present invention. The actuator device 10 includes a first body 12 having a first port 11, a second body 14 having a second port 13 and a third body 17 having a guide member 16 for slidably supporting a plunger member 15 therein. A diaphragm member 18 is fixedly hermetically secured between second and third bodies 14 and 17 at the outer peripheral portion thereof. An adjusting member 34 is provided on a small diameter portion 15a of plunger member 15. 
     Plunger member 15 is connected at an upper end thereof to the inner peripheral portion of diaphragm member 18 having a pair of plates 19a, 19b mounted thereon, and is slidably guided by guide member 16. Therefore, plunger member 15 is axially movable together with diaphragm member 18. A lower portion of small diameter portion 15a of plunger member 15 is connected to an operating rod 32 in association with a throttle valve opening lever of an internal combustion engine (not shown). 
     Within the first, second and third bodies chambers 21a and 21b are defined by the arrangement of diaphragm member 18. Incorporated within chamber 21a is an electromagnetic valve 20 which includes a bobbin 24 on which a solenoid coil 25 is wound, an iron core 23 on which a yoke member 26 is secured, a movable leaf member 27 rotatably movably located on the knife edge of yoke member 26 at one end thereof by means of spring, and a valve member 28 provided on the other end of leaf member 27. Valve member 28 is normally in contact with a seat 29 provided on first body 12 and is normally spaced from a seat 30 provided on the second body 14 by the spring force. Solenoid coil 25 is adapted to receive electric signals from a computer of an engine idling control system in response to vehicle engine operating conditions. 
     Operating chamber 21a is selectively alternatively in communication with first port 11 or second port 13 continuously by means of the operation of valve member 28. Second port 13 receives atmospheric pressure by means of air filter member 31 while first port 11 is, for example, connected with a negative pressure source such as an intake manifold of the internal combustion engine. 
     A spring 22 provided within chamber 21a normally biases diaphragm member 18 downwardly as viewed in FIG. 1. Operating rod 32 is securely fastened to threaded portion 15b of plunger member 15 by means of a lock nut 33 which is of hexagonal external form. Accordingly, rod 32 and plunger member 15 move unitarily. 
     Adjusting member 34 has a hub portion 36 with a stopping flange portion 39, a plurality of extending members 37 which axially extend from the hub portion 36 and a ring shaped portion 38 having a knurled periphery 38a on hub portion 36. A hexagonal nut 35 is inserted within hub portion 36 and is threadedly moved on small diameter portion 15a. Nut 35 is securely caulked between extending members 37 as shown in FIG. 2 and FIG. 3. 
     Extending members 37 are elastically radially deformed upon contact with the hexagonal external face of lock nut 33 at at least one section thereof to radially grip lock nut 33. As a result, such gripping prevents the threaded movement of the nut 35, so that a predetermined stroke length of plunger member 15 as shown by S in FIG. 1 is maintained. 
     When adjusting member 34 is on rotated plunger member 15 through knurled periphery 38a with a predetermined force, nut 35 is threaded axially moved on small diameter portion 15a. Consequently, the stroke of plunger member 15 may be easily varied and adjusted without the use of a tool. 
     In operation, when solenoid coil 25 is energized in response to, for example, operation of the engine-idle control system of an automobile provided with an air-conditioner, leaf member 27 is moved downwardly in FIG. 1 from its illustrated and initial position. Valve member 28 is then separated from seat 29 and is brought in to contact with seat 30. 
     Accordingly, chamber 21a, which has been in communication with atmospheric pressure through port 13, is now in communication with the negative pressure source through port 11. Due to the pressure differential between chambers 21a and 21b, diaphragm member 18, plunger member 15, and plates 19a, 19b move upwardly against the biasing force of spring 22. Operating rod 32 interconnected between the plunger member 15 and throttle valve opening lever will simultaneously move upwardly so as to change the opening degree of the throttle valve. As a result, flange portion 39 is brought in to contact with end portion 16a of plunger member 15, so that the opening degree of the throttle valve is maintained at a predetermind value according to the stroke of plunger member 15 as shown by reference letter S in FIG. 1. 
     When solenoid coil 25 is de-energized, leaf member 27 is returned to its initial position. Valve member 28 is returned to its original position as shown is FIG. 1, and as a result, chamber 21a, which has been in communication with the negative pressure source through port 11, is in communication with atmospheric pressure through port 13, so that spring 22 again biases diaphragm member 18 downwardly so as to return all of the members to their original positions. 
     Various modifications and alterations of this invention will be obvious to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiment set forth herein.