Patent Abstract:
A water pressure switch employs two pivotable plates and springs to control the activation of the pump. The arrangement of the two pivotably plates, the springs and the activation device reduces the space required so that a small box can accommodate all the parts.

Full Description:
FIELD OF THE INVENTION 
   This is a Continuation-In-Part application of applicant&#39;s former patent application with application Ser. No. 11/212,757, filed on Aug. 29, 2005, now U.S. Pat. No. 7,112,753. 

   BACKGROUND OF THE INVENTION 
   A conventional pressure switch  9  is shown in  FIG. 9  and generally includes a push member  91 , a first plate  92 , a second plate  93 , a first contact point  94 , a second contact point  95 , a spring member  96  and a rectangular box  97  which receives all the parts therein. When the pressure of water is too low, the pump can be automatically activated to maintain a desired pressure in pipes. 
   When the pressure of water is high, the push member  91  pushes the first plate  92  which drives the second plate  93  and the first contact point  94  is moved by the second plate  93  to be separated from the second contact point  95  so as to stop the pump. 
   When the water pressure in pipes is lowered and smaller than the spring force of the spring member  96  in the pressure switch  9 , the spring member  96  drives the two contact points  94 ,  95  to be in contact with each other to activate the pump. 
   However, when the direction of water flow form the inlet  98  and the swing direction of the first contact point  94  need a certain space to work so that the box  97  has to be large enough to receive all the parts therein. Besides, the inlet  98  is located off from the center of the box  97  so that it requires a larger space to install the box  97 . 
   The present invention intends to provide a pressure switch wherein the direction of water flow form the inlet and the swing direction of the contact point are the same so that the box can be a cylindrical box and the inlet is located at the central axis of the box. This reduces the manufacturing cost. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a pressure switch which comprises a box and an outer cover is connected to an open end of the box and an inlet is defined through the outer cover, an inner cover is engaged with the open end and has a central hole. A film is located between the outer cover and the inner cover, and has a push portion which extends through the inner cover. An initializing device has a rod and a first spring which is mounted to the rod and one end of the rod extends through a close end of the box. A first plate has a pivot end pivotably connected to the inner cover and a through hole is defined through the first plate. The first plate is located between the first spring and the push portion. A mounting hole is defined through the first plate so that the rod extends through the mounting hole. A second plate extends through the through hole of the first plate and has a pivotal end which is located opposite to the pivot end of the first plate and connected to the inner cover. An activation device is located above the first and second plates and includes a frame and a pull rod which is connected to a center of the frame. A second spring member is connected between a lug of the second plate and the pull rod. A first contact unit and a second contact unit are located on two sides of the pull rod and connected to the frame. When the pull rod is pulled by the second spring, the first and second contact units are in contact with each other. 
   The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows the pressure switch of the present invention; 
       FIG. 2  shows that the first and second contact units are in contact with each other; 
       FIG. 3  shows that the first and second plates are pulled upward; 
       FIG. 4  shows that the first and second contact units are separated from each other; 
       FIG. 5  shows the first plate of the present invention; 
       FIG. 6  shows the second plate of the present invention; 
       FIGS. 7 and 8  show two operation status of a second embodiment of the pressure switch of the present invention, and 
       FIG. 9  shows a conventional pressure switch. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 to 6 , the pressure switch of the present invention comprises a cylindrical box  1  which has a space  11  defined therein and includes a close end  12  and an open end  13 . An outer cover  2  is connected to the open end  13  of the box  1  and an inlet  21  is defined through the outer cover  2  so as to introduce water into the box  1 . An inner cover  3  is engaged with the open end  13  and has a central hole  31 . A film  4  is located between the outer cover  2  and the inner cover  3 , and has a push portion  41  which extends through the central hole  31  of the inner cover  3 . 
   An initializing device  5  located in the box  1  and has a rod  51  and a first spring  52  mounted to the rod  51 . An adjustment member  53  is threadedly connected to the rod  51  and located above the first spring  52 . The rod  51  has one end extending through a hole  64  in the close end  12  of the box  1  and is connected to a nut  54 . The other end of the rod  51  is connected to the inner cover  3 . 
   A first plate  6  has a pivot end  61  pivotably connected to the inner cover  3  and a through hole  62  is defined through the first plate  6 . The first plate  6  is located between the first spring  52  and the push portion  41 . A mounting hole  64  is defined through the first plate  6  and the rod  51  extends through the mounting hole  64 . The first plate  6  includes two openings  63  so that a tip of the push portion  41  may extend therethrough. A second plate  7  extends through the through hole  62  of the first plate  6  and has a pivotal end  71  which is located opposite to the pivot end  61  of the first plate  6  and connected to the inner cover  3 . 
   An activation device  8  is located above the first and second plates  6 ,  7  and including a frame  81  and a pull rod  82  which is connected to a center of the frame  81 . A second spring member  83  is connected between a lug  72  located at a center of the second plate  7  and the pull rod  82 . A first contact unit  84  and a second contact unit  85  are located on two sides of the pull rod  82  and connected to the frame  81 . The frame  81  includes two tip portions  811 ,  812  with the pull rod  82  located therebetween, the two tip portions  811 ,  812  respectively contact the first contact unit  84  and the second contact unit  85 . 
   In order to reinforce the spring force that is applied to the first plate  6 , a third spring  55  is mounted to the rod  51  and located at inner periphery of the first spring  52 . Each of the first and second plates  6 ,  7  has a hook hole  65 / 73  so that a fourth spring  74  is hooked the two respective hook holes  65 ,  73  in the first and second plates  6 ,  7 . 
   The first contact unit  84  has a first upper contact portion  841  and a first lower contact portion  842 , a fifth spring  86  is connected to the first upper contact portion  841 . The second contact unit  85  includes a second upper contact portion  851  and a second lower contact portion  852 , a sixth spring  87  is connected to the second upper contact portion  851 . 
   When the water pressure is lowered, the pull rod  83  is pulled downward by the third spring  55  so that the first and second upper contact portions  841 ,  851  are in contact with the first and second lower contact portions  842 ,  852 . The electrical wires  88  of the first and second contact units  84 ,  85  are powered so as to activate the pump which is not shown. 
   When the water pressure is larger than the force of the first spring  52 , the push portion  41  of the film  4  is pushed inward to push the first plate  6  and pivots the second plate  7  upward. The pull rod  82  connected to the lug  72  on the second plate  7  an the second plate  7  both push the frame  81  so that the first and second upper contact portions  841 ,  851  are separated from the first and second lower contact portions  842 ,  852 . The fifth and sixth springs  86 ,  87  bounce back to ensure all the contact portions are separated to stop the pump. 
   The two tip portions  811 ,  812  are in contact with the two respective centers of the first contact unit  84  and the second contact unit  85  so that the first and second contact units  84  and  85  apply an even force which prevents the pressure switch from shaking. The direction of the water flow from the inlet  21  and the direction of the movement of the fist and second contact units  84 ,  85  are the same, so that only a smaller space is needed and the inlet  21  is located at a center of the box  1  which is convenience for installation. 
   Referring to  FIGS. 7 and 8  which show a second embodiment of the present invention wherein the activation device  8 A is located between the space  11 A and the second plate  7 A, and includes a push rod  82 A which has one end connected to a frame  81 A guided by rails  88 A. The other end of the push rod  82 A is in contact with the lug  72 A of the second plate  7 A. The frame  81 A is connected to a first contact unit  84 A and a second contact unit  85 A located on the two sides of the push rod  82 A. The first contact unit  84 A includes a first upper contact portion  841 A and a first lower contact portion  842 A, the second contact unit  85 A includes a second upper contact portion  851 A and a second lower contact portion  852 A. The first and second contact units  84 A,  85 A are moved with the push rod  82 A so that the first upper and lower contact portions  841 A,  842 A and the second upper and lower contact portions  851 A,  852 A can be in contact with each other or separated from each other. 
   The frame  81 A includes two tip portions  811 A,  812 A which are located on the two sides of the push rod  82 A. The two tip portions  811 A,  812 A are respectively in contact with the first contact unit  84 A and the second contact unit  85 A. The first contact unit  84 A includes a first upper contact portion  841 A and a first lower contact portion  842 A, the second contact unit  85 A includes a second upper contact portion  851 A and a second lower contact portion  852 A. The tip portions  811 A includes a first guide rod  813 A which is connected to the frame  81 A and is in contact with the first upper contact portion  841 A. 
   A first cam  814 A is located on a side of the frame  81 A and opposite to the first upper contact portion  841 A. The first cam  814 A is located corresponding to the first guide rod  813 A. The other tip portions  812 A includes a second guide rod  815 A which is connected to the frame  81 A and is in contact with the second upper contact portion  851 A. A second cam  816 A is located on the side of the frame  81 A and opposite to the second upper contact portion  851 A. The second cam  816 A is located corresponding to the second guide rod  815 A. A fifth spring  86 A is mounted on the first cam  814 A and a sixth spring  87 A is mounted on the second cam  816 A. In this embodiment, the fifth spring  86 A and the sixth spring  87 A are springs and located opposite to the first and second contact units  85 A,  86 A. 
   When the second plate  7 A moves downward, the push rod  82 A of the activation device  8  moves downward to drive the first upper contact portion  841 A of the frame  81 A to be in contact with the first lower contact portion  842 A. The second upper contact portion  851 A is in contact with the second lower contact portion  852 A. By the spring forces of the fifth spring  86 A and the sixth spring  87 A, the first upper contact portion  841 A of the first contact unit  84 A is in contact with the first lower contact portion  842 A, and the second upper contact portion  851 A of the second contact unit  86 A is in contact with the second lower contact portion  852 A. By this way, the circuit is connected between the first and second contact units  84 A,  85 A so that the pump is activated. 
   While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.

Technology Classification (CPC): 7