Patent Publication Number: US-6984798-B1

Title: Safety switch

Description:
FIELD OF THE INVENTION 
   The present invention relates to switches, and particularly to a safety switch, wherein the safety switch has a simple structure and is made of a fewer elements. Thereby the manufacturing process is simplified. The fault rate of the safety switch is reduced. 
   BACKGROUND OF THE INVENTION 
   A safety switch is used in electric devices for interrupting the power connection as overloading so as to protect the device to be in safety condition. 
   Most of the prior art safety switch can achieve the effect of turning off power so as to prevent fire accident. However the structure is complicated, has too many parts, so that a large amount of parts are necessary. Thereby cost is high. All these are main concern in the manufacturing of safety switch. 
   SUMMARY OF THE INVENTION 
   Accordingly, the primary object of the present invention is to provide a safety switch, wherein the safety switch has a simple structure and is made by a fewer elements. Thereby the manufacturing process is simplified. The fault rate of the safety switch of the present invention is reduced. 
   To achieve above objects, the present invention provides a safety switch which comprises the following elements. 
   A hollow body  10  has an opening at an upper end thereof and a lower end of the hollow body has three slots which are spaced arranged. 
   A button is pivotally installed upon the opening of the hollow body. A press block downwards extends from a pivotal point of the button. 
   A first power terminal is installed at one of the three slots. 
   A second power terminal is installed at another of the three slots. 
   A load terminal is installed at the other slot of the three slots which is located between the first power terminal and the second power terminal. The load terminal is electrically connected to the second power terminal through a neon bulb and a resistor. An upper side of the load terminal is installed with an electric silver sheet. 
   An elastomer is a U shape metal piece. One end of the elastomer is buckled to an upper end of the load terminal and another end thereof is buckled to the press block of the button. 
   A metal sheet is installed at a lower side of the button. The metal sheet is made of a compound metal having materials of different expansion coefficient. One end of the metal sheet is connected to an upper end of a power terminal. Another end thereof is bent to have a U shape structure. A lower side of the U shape structure is installed with a conductive silver sheet corresponding to the electric silver sheet of the load terminal. 
   In application, the button is pressed to press the metal sheet so that the conductive silver sheet of the metal sheet is electrically connected to the electric silver sheet of the load terminal. Then the press block of the button will move slightly through a small angle so as to compress the elastomer. 
   The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the present invention. 
       FIG. 2  is an exploded perspective view of the first embodiment. 
       FIG. 3  is a cross sectional view about the first embodiment. 
       FIG. 4  is a cross sectional view showing the application of the first embodiment of the present invention. 
       FIG. 5  is a cross sectional view showing the use of the metal sheet in the first embodiment of embodiment. 
       FIG. 6  is a cross sectional view of the second embodiment of the present invention. 
       FIG. 7  is a cross sectional view showing the use of the second embodiment of the present invention. 
       FIG. 8  is a cross sectional view about the third embodiment of the present invention. 
       FIG. 9  is a cross sectional view showing the use of the third embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In order that those skilled in the art can further understand the present invention, a description will be described in the following in details. However, these descriptions and the appended drawings are only used to cause those skilled in the art to understand the objects, features, and characteristics of the present invention, but not to be used to confine the scope and spirit of the present invention defined in the appended claims. 
   With reference to  FIGS. 1 to 3 , the first embodiment of the present invention has the following elements. 
   A hollow body  10  has an opening  100  at an upper end thereof and a lower end of the hollow body  10  has three slots  101  which are spaced arranged. 
   A button  11  is pivotally installed upon the opening  100  of the hollow body  10 . A press block  110  downwards extends from a pivotal point of the button  11 . 
   A first power terminal  12  is installed at one slot of the three slots  101 . 
   A second power terminal  13  is installed at another slot of the three slots  101 . 
   A load terminal  14  is installed at the other slot of the three slots  101  which is located between the first power terminal  12  and the second power terminal  13 . The load terminal  14  is electrically connected to the second power terminal  13  through a neon bulb  15  and a resistor  16 . An upper side of the load terminal  14  is installed with an electric silver sheet  140 . 
   An elastomer  17  is a U shape metal piece. One end of the elastomer  17  is buckled to an upper end of the load terminal  14  and another end thereof is buckled to the press block  110  of the button  11 . 
   A metal sheet  18  is installed at a lower side of the button  11 . The metal sheet  18  is made of a compound metal having materials of different expansion coefficient. One end of the metal sheet  18  is connected to an upper end of a power terminal  12 . Another end thereof is bent to have a U shape structure  180 . A lower side of the U shape structure  180  is installed with a conductive silver sheet  181  corresponding to the electric silver sheet  140  of the load terminal  14 . 
   With reference to  FIG. 4 , in application, the button  11  is pressed to press the metal sheet  18  so that the conductive silver sheet  181  of the metal sheet  18  is electrically connected to the electric silver sheet  140  of the load terminal  14 . Then the press block  110  of the button  11  will move slightly through a small angle so as to compress the elastomer  17 . 
   Referring to  FIG. 5 , when current overloads, since the metal sheet  18  is made of a compound metal having materials of different expansion coefficient. The U shape structure  180  of the metal sheet  18  will deform so as to expand to make the conductive silver sheet  181  separate from the electric silver sheet  140  so as to lift the button  11  upwards. By the elastic force of the elastomer  17 , the press block  110  of the button  11  will be pushed. As a result, the button  11  will lift upwards to turn off the circuit. 
   When the temperature of the metal sheet  18  is not reduced, the U shape structure  180  will not restore to the original shape. At this moment, if the button  11  is pressed again, the conductive silver sheet  181  will not electrically connected to the electric silver sheet  140 . Thereby the circuit is in safety condition. 
   Referring to  FIGS. 6 and 7 , the second embodiment of the present invention is illustrated. The difference of the second embodiment from the first embodiment is that one end of the metal sheet  18  connected to the first power terminal  12  has no U shape structure. The conductive silver sheet  181  is directly installed on the metal sheet  18  at a position corresponding to that of the electric silver sheet  140 . If the current overloads, the connection of the metal sheet  18  and the first power terminal  12  will deform so that the metal sheet  18  curls upwards to drive the button  11  to eject upwards. Thereby by the action of the elastomer  17  and the press block  110 , the same effect of the first embodiment is achieved. 
   Referring to  FIGS. 8 and 9 , the second embodiment of the present invention is illustrated. The difference of the third embodiment from the second embodiment is that one end of the metal sheet  18  has the conductive silver sheet  181  which is bent toward the button so as to increase the elastic force as over current occurs in the metal sheet  18 . 
   The present invention has a simple structure and is made a fewer elements. Thereby the manufacturing process is simplified. The fault rate of the safety switch of the present invention is reduced. 
   The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.