Abstract:
A pressure switch. The switch includes a pressure sensor device adapted for receiving the input pressure and then moving the link rod due to the deformation caused by the input pressure. The switch includes a contact point fine-tuner having a first contact point controlled by the link rod, and is capable of separating or contacting a second contact point, and the contact point fine-tuner is mounted on a frame extended upwards from the pressure sensor device. The link rod of the pressure sensor device has a rotary plate, and the rotary plate includes a top leaning portion. By adjusting the position of the rotary plate on the link rod the controlling relationship between the first contact point of the contact point fine-tuner is attached to adjust different predetermined pressure values.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a pressure switch, which is applicable for the control of a pressure switch of a small air compressor device, and is capable of fine-tuning the values for configuration and the pressure difference thereof. 
     2. Description of the Related Art 
     There are many conventional pressure switches and those incorporating the application of an air compressor are frequently used, which mainly use the principle for the Baton tube or membrane. When the pressure of the compressor is accumulated to a certain predetermined value, the switch will have intermittent actions and stop the air compressor from increasing its pressure. Until the pressure in the air compressor is reduced to a certain predetermined value, the switch will resume its action of continual increase of the pressure. The pressure switch of this sort has a factory default value for a maximum pressure and a minimum pressure, such as 25-35 pounds per square inch (p.s.i.) or 95-105 p.s.i. Therefore, when there is a need for several maximum and minimum pressure differences, we have to buy pressure switches having different predetermined values for the upper limit and lower limit of the pressure, and it is relatively inconvenient and more expensive. The pressure switch of some large air compressors may have the function of fine-tuning the predetermined pressure value and the pressure difference, but its application is too complicated and has a numerous and large lever mechanical structure for the control of the transmission between the pressure source and the switch, and is not applicable for the small air compressors which only allows for very small space for the control between pressure source and the switch. 
     SUMMARY OF THE INVENTION 
     The objective of this invention is to provide an improved pressure switch which comprises a pressure sensor means for receiving the input pressure and then moving the link rod due to the deformation caused by the input pressure. A contact point fine-tuner having a first contact point is controlled by the link rod and is capable of separating or contacting a second contact point, and the contact point fine-tuner is mounted on a frame that is extended upwards from the pressure sensor means. The link rod of the pressure sensor means has a rotary plate, and such rotary plate comprises a top leaning portion. By adjusting the position of the rotary plate on the link rod, this changes the controlling relation between the first contact point of the contact point fine-tuner to adjust different predetermined pressure values. The contact point fine-tuner has a fine-tuning screw set, which changes the distance between the first contact point and the second contact point by the displacement of the screw set in order to adjust different pressure differences controlled by the pressure switch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiment. The description is made with reference to the accompanying drawings, in which: 
     FIG. 1 shows the structure of a preferred embodiment of the present invention partially in section. 
     FIG. 2 shows the movement of the contact point fine-tuner device according to a preferred embodiment of the present invention. 
     FIG. 3 shows the structure of the contact point fine-tuner device of another preferred embodiment of the present invention. 
     FIG. 4 is a side view of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the detailed description of the preferred embodiments, it should be noted that like elements are generally indicated by the same reference numerals throughout the disclosure. 
     Referring to FIG. 1, a pressure switch  1  of the preferred embodiment according to the present invention can be accommodated in a cylindrical housing  2 , which makes adjustment to the pressure switch in the interior thereof by opening a lid member  3  that covers the top of the housing. Meanwhile, the pressure switch has a first contact point  133  and a second contact point  140  in contact with end sleeves  41 ,  42  of an electric wire  4  that extend to the exterior of the housing  2  and is coupled with an air compressor. The structure of the pressure switch mainly comprises a pressure sensor device  11  and a contact point fine-tuner device  13 , wherein the pressure sensor device  11  comprises a bottom base of a conducting pipe  112  for coupling to a pressure source, and the bottom base has a pressure chamber  113  at a groove region which is covered by a sealed ring  115  of a flexible member on a membrane  114  at the curved surface of a flexible metallic substance which latches the membrane  114  and the bottom base  111  by a hooped ring  116  to seal the pressure chamber  113 , so that gas can only be input through the air pipe  117  of the conducting pipe  112  to the pressure chamber  113 . The hooped ring  116  has a self hooped ring peripherally extending towards the center thereof and inclined to the frame base  118 , and a link rod  119  is mounted on the membrane  114 . The link rod  119  having a shoulder base  120  is disposed near the membrane  114  and screw threads are formed on the link rod  119 . The link rod  119  corresponding to the opposite axial end of the membrane  114  has a rotary plate  121  mounted onto it by screws. The upper section of the rotary plate  121  has a supporting portion  122  with a smaller cross-sectional diameter, and the lower section of the rotary plate  121  has a gear  123  with a structure similar to that of ordinary gears. An elastic member  124  composed of a tension spring is mounted outside the link rod  119  between the lower section of the gear  123  of the rotary plate  121  and the upper section of the shoulder base  120  of the link rod  119 . The said contact point fine-tuning device  13  comprises a fixing base  131  on the middle frame  118  of the pressure sensor device  11  mounted into position by screws, and the fixing base  131  is made of insulating material, and one of its ends is bent into a bent section  132 . The lower section of the fixing base  131  forms an electrically conductive bracket  134  with a first contact point  133 , and a stopper section  135  is disposed at the position extending downwards, and a blocking section  136  is formed at an end thereof having an open groove at its lower portion. The blocking section  136  close to the middle section is slightly concave, and a spring  138  of the upper contact point  137  at an end extends downwards at that location. The spring  138  has a latch hole (not shown in the figure) latched by an elastic member  139  of the stopping section  135 . An electrically conductive bracket  141  of the second contact point  140  is positioned at the lower portion of the bent section  132  of the fixing base  131 , and one of the ends of the bracket  141  has a lower contact point  142  that always keeps in close contact with the upper contact point  137  under normal conditions, and a fine-tune screw member  143  is positioned above the upper contact point  137  and attached to the fixing base  131 , and the screw member  143  is supported by the an elastic member  144 . 
     The preferred embodiment of the present invention incorporates the coupling of the pressure source with the conducting pipe  112  of the pressure sensor device  11  of the pressure switch  1 , and permits discharge of air pressure into the pressure chamber  113  through the air pipe  117  which makes the pressure chamber  113  to expand and move the membrane  114  which in turn moves the link rod  119  upwards. By pressing the elastic member  139  of the contact point fine-tuning means with the upper support section of the rotary plate  121 , the link rod  119  moves the upper contact point  137  at one end of the spring bracket  138  away from the lower contact point  142  on the electrically conductive bracket  141  to separate the contact points as shown in FIG.  2 . The pressure in the pressure chamber  113  has a first set value, and the first set value is one that has to be overcome when the air compressor increases the pressure to a certain extent. 
     When the pressure of the air compressor is released after use, the pressure chamber  113  in the pressure switch is reduced, and the link rod  119  on the membrane  114  and the upper support section of the rotary plate  121  moves downwards. Since there is no other external force on the elastic member  139 , the resuming force on the member  139  will bring the upper contact point  137  contacting the spring bracket  138  downwards to the lower contact point  142  on the electrically conductive bracket  141  as shown in FIG.  1 . The pressure in the pressure chamber  113  has a second set value, and the second set value is also the value that needs to be overcome when the air compressor increases its pressure to a certain extent. 
     Due to the elasticity of the elastic member  139  of the contact point fine-tuning device  13 , when the upper support section  122  of the rotary plate  121  is pressed, the member  139  will not immediately move the upper contact point  137  of the spring bracket, there will be a delay time period, so that a pressure difference is generated between said first set value and second set value. When the upper contact point  137  and the lower contact point  142  are separated from each other, the elastic member  139  has already been pressed by the support section  122  to become a curved shape. Only when the support section  122  moves down to the elastic member  139  and resumes the substantially position with the spring bracket  138  (this time period is the delay time, which occurs when the pressure difference is generated), then the spring bracket  138  can bring the upper contact point  137  and the lower contact point  142  together by moving itself downward. 
     To adjust the upper limit for the pressure, the gear  123  of the rotary plate  121  is moved to lift or lower the support section  122 . If the support section  122  is lifted, the section  122  reaches the elastic member  139  more quickly, therefore this permits for a lower upper limit for the pressure, however, the upper limit for the pressure will be higher. 
     The difference between the upper limit and the lower limit for the pressure (that is the adjustment of the lower limit of the pressure) depends on the extent of the downward screwing of the fine-tuning screw  143  to change the time interval when the upper contact point  137  and the lower contact point  142  are separated from each other. If the time interval is reduced, once the upper support section  122  of the rotary plate  121  drops, the faster the upper contact point  137  will reach the lower contact point  142 , and the controlled pressure difference will be smaller, otherwise the pressure difference will be greater. 
     The second preferred embodiment of the present invention as shown in FIG. 3 provides a contact point fine-tuning device  5  which substitutes the spring bracket  138  and an elastic member  139  shown in FIG. 1 with a single-piece composed of a spring member  51  having the elastic property. The end of the spring member  51  includes an upper contact point  52 , and the other end is split into a bent spring bracket  53  supporting the blocking section  55  of the electrically conductive bracket  54  having a slightly concave groove at the middle section, and the other end is split into a longer spring bracket  56  latched to the stopper section  57  of the foregoing electrically conductive bracket  54 . Therefore, the upper support section  61  of the rotary plate  6  acts on the spring bracket  56  in a very similar manner as the action of the upper support section on the elastic member  139  as shown in FIG. 1 for the first preferred embodiment. In addition, the upper support section  61  of said rotary plate  6  is made of metallic material to reduce wear. The bent section  59  of the fixing base  58  can be moved to the back of the fixing base as shown in FIG.  4 . 
     The mechanical design of the preferred embodiment according to the present invention does not only fine-tune the set pressure value and the pressure difference, but it also places the rotary plate on the end of the opposite axial direction of the membrane with respect to the link rod, and the elastic member on the contact point fine-tuning device pressed by the upper support section on the rotary plate is directly disposed on the top end of the rotary plate. The overall contact point fine-tuning means is fixed on the frame extended upward from the pressure sensor means which allows the interaction of each components to be operated in a very small space, and is applicable for use as the pressure control switch for small air compressors. 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.