Abstract:
A control device for an air compressor includes a pressure control device having a pressure release valve adapted to be operably connected to the compressor, a fuel valve connectable to the engine and a three-way valve sandwiched between the pressure release valve and the compressor, a switching device having a pivotal plate to selectively activate fuel supply to the engine from the fuel valve and a cylinder connected to the pivotal plate via a cylinder shaft extendable out of the cylinder to drive the pivotal plate to pivot and an air pressure device to detect air pressure in the air tank so as to activate extension of the cylinder shaft out of the cylinder to deactivate the fuel supply from the fuel valve and air pressure release process via the pressure release valve.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a control device, and more particularly to the engine control device in an air compressor to effectively control operation of the engine based on air pressure inside the air compressor to prolong life span of the engine.  
         [0003]     2. Description of Related Art  
         [0004]     When a conventional air compressor is in operation, the engine, which is mounted on top of the air compressor to drive the compressor to compress air inside the air tank is either in full operation or the engine is not running at all. That is, when the pressure sensor inside the air tank detects that the air pressure in the air tank is not enough, the pressure sensor sends a signal to start the engine, which in turn drives the compressor to increase the air pressure inside the air tank. Therefore, whenever the engine is running, the engine is in full operation. There is no difference in the engine operation whether the air pressure inside the air tank is far below or slightly below the standard pressure required. This kind of design does meet the requirement to boost the air pressure inside the air tank. Because the engine is always in full thrust when the air pressure inside the air tank is below standard it will experience excessive wear and so the life span of the engine does not reach expectations.  
         [0005]     To overcome the shortcomings, the present invention tends to provide an improved engine control device to mitigate the aforementioned problems.  
       SUMMARY OF THE INVENTION  
       [0006]     The primary objective of the present invention is to provide an improved engine control device to control rotation speed of the engine depending on the pressure inside the air tank so as to prolong the life span of the engine.  
         [0007]     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a schematic view showing the relationship between the control device of the present invention and the air compressor;  
         [0009]      FIG. 2  is a block diagram showing the control device of the present invention is in connection with the engine and the compressor so as to control the operational efficiency of the engine;  
         [0010]      FIG. 3  is a schematic side plan view showing the structure of the control device;  
         [0011]      FIG. 4  is a side plan view showing the relationship between the knob and the driving plate; and  
         [0012]      FIG. 5  is a schematic view showing that the pivotal plate is driven by the movement of the cylinder such that the engine efficiency is increased due to the activation of the fuel valve by the control line. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]     With reference to  FIG. 1 , it is noted that an air compressor ( 10 ) is normally equipped with a compressor and a motor. However, the motor is able to be replaced by an internal combustion engine. Because both the structure and the operation of the motor and the structure of the engine are conventional in the art, detailed descriptions thereof are omitted for brevity. The following description is aimed to the air compressor having a compressor and an engine to drive the compressor.  
         [0014]     With reference to  FIGS. 1 and 2 , the air compressor ( 10 ) is further provided with a control device ( 20 ) in connection with the engine ( 23 ) on top of the air compressor ( 10 ) which has a compressor ( 21 ) in connection with the engine ( 23 ) by a connection element ( 22 ) i.e. a belt or the like and an air tank ( 25 ) to receive air therein.  
         [0015]     The control device ( 20 ) includes a pressure control device ( 30 ) and a switching device ( 40 ). The pressure control device ( 30 ) includes a housing ( 31 ), a pressure release valve ( 33 ) mounted on the housing ( 31 ) and in connection with a three-way valve ( 24 ) which is in connection with the air tank ( 25 ), a fuel valve ( 34 ) mounted on the housing ( 31 ) and in connection with the engine ( 23 ). The pressure release valve ( 33 ) is able to release all the air pressure in the pipes (not numbered) connected to the air compressor ( 10 ) and the fuel valve ( 34 ) is able to increase fuel supply to the engine ( 23 ) to increase the working efficiency of the engine ( 23 ).  
         [0016]     The switching device ( 40 ) includes a pivotal plate ( 41 ), a driving plate ( 43 ) and a cylinder ( 45 ). The pivotal plate ( 41 ) is pivotally connected to a side face of the housing ( 30 ) at a first distal end thereof and a second distal end of the pivotal plate ( 41 ) is connected to the cylinder ( 45 ). The driving plate ( 43 ) is also pivotally connected to the housing ( 30 ).  
         [0017]     With reference to  FIG. 3 , it is noted that the second distal end of the pivotal plate ( 41 ) is defined with an elongated hole ( 412 ) to receive therein a pin ( 452 ) which is securely extended into a cylinder shaft ( 451 ) extending out from the cylinder ( 45 ) so that movement of the cylinder shaft ( 451 ) is able to drive the pivotal plate ( 41 ) to pivot inside the housing ( 30 ). The driving plate ( 43 ) is provided with a pivotal point ( 431 ) securely connected to the side face of the housing ( 30 ) and a ball ( 432 ) extending from a bottom face of the driving plate ( 432 ).  
         [0018]     Referring back to  FIG. 2 , it is noted that the compressor ( 21 ) is connected to a first end ( 241 ) of the three-way valve ( 24 ). A second end ( 242 ) of the three-way valve ( 24 ) is connected to the air tank ( 25 ) and the fuel valve ( 33 ) is connected to a third end ( 243 ) of the three-way valve ( 24 ). Furthermore, a pressure regulator ( 26 ) is sandwiched between the cylinder ( 45 ) and the air tank ( 25 ) to regulate the air pressure in the air tank ( 25 ). That is, the pressure regulator ( 26 ) is able to sense the air pressure difference inside the air tank ( 25 ). If the air pressure inside the air tank ( 25 ) falls below a standard, the pressure regulator ( 26 ) drives the cylinder ( 45 ) to move, which in turn extends out the cylinder shaft ( 451 ) to push the pivotal plate ( 41 ) to pivot.  
         [0019]     With reference to  FIGS. 4 and 5 , the operation of the control device of the present invention starts from the activation of the release valve ( 33 ) by pivotal movement of a knob ( 44 ) which is mounted on an outer side face of the housing ( 30 ) and securely connected to the driving plate ( 43 ) at a pivotal point ( 431 ) of the driving plate ( 43 ). Due to the pivotal movement of the knob ( 44 ), the driving plate ( 43 ) is driven to pivot and the ball ( 432 ) mounted on the bottom of the driving plate ( 43 ) is also driven to move. Because the pivotal plate ( 41 ) is immediately adjacent to the driving plate ( 43 ), the pivotal movement of the driving plate ( 43 ) forces the pivotal plate ( 41 ) to pivot as well. While the pivotal plate ( 41 ) is moved, an extension ( 331 ) extending out from the release valve ( 33 ) is engaged with a side face of the pivotal plate ( 41 ), which activates the air pressure release process in the pipes, as shown in  FIG. 3  so as to allow the compressor ( 21 ) to pump air into the air tank ( 25 ). After the air pressure in the pipes is released and after the engine ( 23 ) is actuated, a recoil force in the cylinder ( 45 ) pulls the cylinder shaft ( 451 ) back to the cylinder ( 45 ). Because the fuel valve ( 34 ) is connected to the side face of the pivotal plate ( 41 ) via a control line ( 341 ), the leftward pivotal movement (as shown in the arrow in  FIG. 5 ) of the pivotal plate ( 41 ) activates the fuel valve ( 34 ) to increase fuel supply to the engine ( 23 ) such that the engine ( 23 ) is able to work in a condition to produce more power than a condition when there is no additional fuel supplied to the engine ( 23 ).  
         [0020]     Reviewing the operation of the control device of the present invention, it is noted that after the engine ( 23 ) is actuated and the compressor ( 21 ) starts pump air into the air tank ( 25 ), the air pressure in the air tank ( 25 ) increases and when it finally reaches its standard value, the air pressure in the air tank ( 25 ) pushes open the pressure regulator ( 26 ) so as to extend the cylinder shaft ( 451 ). After the cylinder shaft ( 451 ) is extended, there is no force applied to the control line ( 341 ) such that the fuel valve ( 34 ) is not fully activated and therefore the engine ( 23 ) is not working at its full extent. Therefore, after the installation of the control device to the air compressor ( 10 ), the engine working effect is dependent from the air pressure inside the air tank ( 25 ) such that the engine ( 23 ) needs not work at its full thrust at all times and thus the life span of the engine ( 23 ) is prolonged.  
         [0021]     Preferably, the engine used in this embodiment is a four-stroke engine such that the fuel supply to the engine ( 23 ) is able to be effectively controlled via the fuel valve ( 33 ). Furthermore, the cylinder ( 45 ) is provided with a spring (not numbered) inside the cylinder ( 45 ) to securely connect to the cylinder shaft ( 451 ) so that the cylinder shaft ( 451 ) is pulled backward into the cylinder ( 45 ) after the air pressure in the pipes is released.  
         [0022]     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the fill extent indicated by the broad general meaning of the terms in which the appended claims are expressed.