Abstract:
A switch structure which includes an alloy piece, a contact control device, and a push device is disclosed. The contact control device includes an elastic part and connects to an end part so that the end part may reciprocally move with respect to the contact control device in a horizontal direction. The end part normally contacts with the upper side of the stopper placed in the switch body and is used to push the push device towards the end part when the alloy piece is overheated and strain is generated due to the current flowing through the alloy piece. The end part then elastically contracts and escapes from the stopper to fall down so that another end of the contact control device projects upwards and does not press the elastic contact plate. Therefore, the elastic contact plate may escape from the two contact points to cut off the power source rapidly by the elastic force to achieve the purpose of safety.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a switch structure, and more specifically, to a power switch with a simpler structure which is capable of switching off the power source when the current is overloaded. 
     BACKGROUND OF THE INVENTION 
     Power switches with only two states of ON/OFF function controlled manually have been widely used in many appliances. However, it is risky to use the above power switches when the power source is unstable because overheating may occur due to overloading of the appliance and the wire easily catches fire. The user can not be aware of such latent danger since overloading and overheating are invisible. Therefore, improved power switches have been greatly needed to overcome the danger. 
     Some improved power switches in the prior arts includes an alloy element composed of more than one metal to automatically shut off the power source when the alloy element is thermally deformed because of overheating. 
     For example, a conventional power switch comprises an alloy piece, a lever, and a cam actuator. The lever is actuated by the alloy piece, and the cam actuator is used to coordinate with a seesaw actuator. Thermal deformation of the alloy piece causes the lever to move, and then the cam actuator loses support, escapes and further shuts off the power source. Overheating may occur on he alloy piece. The above power switch uses the lever, the cam actuator, and the seesaw actuator to indirectly control the conductive plate, which is used to contact with the power source. The response of the power off operation in the above power switch when overheating occurs is so slow that the overloaded current may flow into the operating appliance in a short time to damage the appliance. Additionally, the conductive plate and the alloy piece need the wire to connect to each other, and the whole structure is complicated to cause the manufacturing difficult. The alloy piece has to actuate the seesaw actuator and the lever to escape. The function of automatic power off may incorrectly operate. 
     Furthermore, another conventional power switch uses the thermal deformation of the alloy piece to push a limited position base such that a button can automatically escape and return back. The button is used to directly contact with the contact point of the power source so that the button may conduct the overloaded current when overheating occurs. The whole structure is still complicated. In summary, those improved power switches in the prior arts can partly overcome the danger of overheating for the appliance but the response is slow and the whole structure is complicated. An advanced power switch with simpler structure and a short response time is greatly desired. 
     SUMMARY OF THF INVENTION 
     An object of the present invention is to provide a power switch, which consists of an alloy piece, a contact control device, and a push device. The contact control device includes an elastic part and connects to an end part so that the end part may reciprocally move with respect to the contact control device in a horizontal direction. The end part normally contacts with the upper side of the stopper placed in the switch body and is used to push the push device towards the end part when the alloy piece is overheated and strain is generated due to the current flowing through the alloy piece. The end part then elastically contracts and escapes from the stopper to fall down so that another end of the contact control device projects upwards and does not press the elastic contact plate. Therefore, the elastic contact plate may escape from the two contact points to shut off the power source rapidly by the elastic force to achieve the purpose of safety. 
     Other features and advantages of the invention will become apparent from the following description of the invention which refers to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a tree-dimensional exploded diagram according to the present invention; 
     FIG. 2 is a sectional view of the present invention illustrating the situation of the present invention when the switch is OFF; 
     FIG. 3 is a sectional view of the present invention illustrating the situation of the present invention when the switch is ON; 
     FIG. 4 is a sectional view of the present invention illustrating the operation of the present invention when the current is overloaded; 
     FIG. 5 is a sectional view of the present invention illustrating the operation of the present invention when the current is overloaded; 
     FIG. 6 shows a second embodiment of the present invention with a second control device; 
     FIG. 7 shows a third embodiment of the present invention with a third control device; 
     FIG. 8 shows a fourth embodiment of the present invention with a fourth control device; 
     FIG. 9 shows a fifth embodiment of the present invention with a fifth control device; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, the power switch of the present invention comprises a switch cover body  10 , an elastic device  20 , a switch body  30 , a push device  60 , an alloy piece  70 , and an elastic contact plate  80 . 
     The switch cover body  10  consists of a concave cambered surface  11  on the surface, two fulcrums  12  on two opposite sides, respectively, and a triangular piece  13  on the bottom. The triangular piece  13  has a supporting rod hole  14 . 
     The elastic device  20  has a hook body  21  at one end, which hooks the positioning rod  37  of the switch body  30  and the slit  371  on the inner side. 
     The switch body  30  is a hollow shell with an opening. The opening  31  on the top side connects to the switch cover body  10 . The bottom side of the switch body  30  has a plurality of inserting grooves  32 , which connect to the first contact terminal  33  and the second terminal  34 , respectively. The second terminal  34  has a lower contact point  341  on the top side. The switch body  30  further has a stopper  35 , a fixing pillar  36 , a positioning rod  37 , an axle rod  38 , and a support rod  39  on the inner wall. 
     The contact control device  40  includes a convex hole  41 . An elastic part(spring)  42  is placed in the convex hole  41 . A pair of protruding rods  44  are located on two opposite upper and lower sides of the contact control device  40 . On end of the contact control device  40  forms an oblique actuating part  45 , which has a vertically elliptic fixing hole  451  used to connect the contact control device  40  to the fixing pillar  36  of the switch body  30 . Additionally, a hole  46  is located at a suitable place on the contact control device  40 . A supporting rod  47  of the contact control device  40  is used to connect to the supporting rod hole  14  of the switch cover body  10 . 
     The contact control device  40  further includes an end part  50 , which has a top support end  51  as a hook at one end. The bottom side of the end part  50  contacts with the upper side of the stopper  35  of the switch body  30 . A push plate  53  is included in the outer side of the top support end  51 . A slot hole  52  vertically penetrates through the end part  50  and combines with the protruding rod  44  so as to joint with the contact control device  40 . 
     Moreover, the outer end of the elastic part(spring)  42  in the contact control device  40  may joint with a top push part  43  to form a shape of arc so as to more smoothly connect the end part  50  to the contact control device  40 . 
     The push device (push bar) 60  is composed of a push device head  61  and a push device end  62  to form an obtuse angle. An axial hole  63  to joint the push device head  61  and the push device end  62  is used to fix to the axle rod  38  of the switch body  30 . A torsion spring  64  which rotates around the axle rod  38  and connects to the push device head  61  and the support rod  39  is used to further provide recovery force for the push device(push bar)  60 . 
     The alloy piece  70  with an opening to the bottom side is hooked by the push device head  61 . 
     The elastic contact plate  80  has a contact hole  81  at one end. A upper contact point  82  is combined with the bottom side of the elastic contact plate  80 . 
     The above elastic contact plate  80  is joint to one leg of the alloy piece  70  by a fixing base  71  and a rivet  72 . Another leg of the alloy piece  70  is fixed to the first contact end  33  so that the elastic contact plate  80  is on the first contact end  33  and the second contact end  34 . 
     The ON/OFF operation of the present invention includes OFF, ON, and power off during overloading. The following is used to describe in more details. 
     FIG. 2 illustrates the OFF operation according to the present invention. The OFF operation means the operator is required to open the switch to cut off the power source. When the operator pushes down the right end of the switch cover body  10 , the elastic device  20  spreads upwards. The supporting rod  47  accordingly pulls up the actuating part  45  of the contact control device  40 . The elastic contact plate  80  spring upwards because the actuating part  45  does not press the elastic contact plate  80 , so as to separate the upper contact point  82  and the lower contact point  341 . The first contact end  33  and the second contact end  34  is then open-circuited to cut off the power source. 
     FIG. 3 illustrates the ON operation according to the present invention. The elastic device  20  is deformed when the operator pushes down the left end of the switch cover body  10 . The switch cover body  10  counterclockwise rotates around the fulcrum  12  to make the supporting rod hole  14  also counterclockwise arc moves around the fulcrum  12 (towards left direction in the present invention). The upper end of the supporting rod  47  presses the contact control device  40  and then the actuating part  45  downwards pushes the elastic contact plate  80  to connect the upper contact point  82  on the bottom side of the elastic contact plate  80  to the lower contact point  341  of the second contact end  34 . The external power source flows through the first contact end  33 , the alloy piece  70 , the elastic contact plate  80 . the upper contact point  82 , and the lower contact point  341  to the second contact end  34  as an electric loop. 
     It should be noted that the top support end  51  of the end part  50  does not move and contacts with the stopper  35 . 
     With reference to FIGS. 4 and 5, the alloy piece  70  bends towards one side (outwards in this embodiment)due to thermal deformation to pull the push device head  61  of the push device(push bar)  60  when the current is overloaded. The push device(push bar)  60  rotates around the axle rod  38  and the push device end  62  reverse pushes the push plate  53  of the end part  50 . The end part  50  contracts towards the contact control device  40  so that the top support end  51  escapes from the top of the stopper  35 . The end part  50  and the right end of the contact control device  40  fall down without the support of the stopper  35 . The actuating part  45  at the left end of the contact control device  40  rotates around the convex hole  46  to move upwards so that the elastic contact plate  80  can move upwards with the actuating part  45 . Therefore, the upper contact point  82  escapes from the lower contact point  341  to cut off the power source. 
     Additionally, after the end part  50  falls down, the elastic part(spring)  42  in the contact control device  40  spreads out and the top push part  43  pushes the end part  50  so that the end part  50  returns back to the original state of spreading out. 
     If the switch cover body  10  is not applied by any external force, the elastic device  20  will spread upwards to push up the switch cover body  10 . The switch cover body  10  counterclockwise rotates around the fulcrum  12  to OFF position (as shown in FIG. 2) so that the contact control device  40  is pulled up by the supporting rod  47  and the alloy piece  70  cools down to return to the original state. The bottom side of top support end  51  included in the end part  50  presses the top side of the stopper  35  once again. This is OFF state (as shown in FIG. 2) to prepare for the next ON state. 
     With reference to FIG. 6, an arc elastic plate  48  may replace the elastic part(spring)  42  in the contact control device  40  as the second embodiment of the present invention. 
     FIG. 7 is the third embodiment of the present invention, which is modified from FIG.  6 . The front end of the arc elastic plate  48  extends outwards to form a push plate  481 , which has a top support end (hook) 482  on the top side to push the top side of the stopper  35 . The top support end (hook) 482  is used to provide an arc to cause the contact control device  40  to return back to the original OFF state so that the bottom side of the top support end (hook) 482  can smoothly push he top side of the stopper  35 . The push plate  481  causes the push device  60  to push some desired part, as shown in FIGS. 4 and 5. 
     FIGS. 8 and 9 show the fourth embodiment of the present invention. Another end of the contact control device  40  includes a convex hole  41 ′, which is bigger at the inner end and smaller at the outer end. The elastic part(spring)  42  in the convex hole  41 ′ pushes the end part  50  of the top support end  51 ′. The end part  50  presses down the top side of the stopper  35 . The front end of the top support end  51 ′ forms an arc surface to cause the push device  60  to push some desired part. The end part  50  may smoothly slides down from the top side of the stopper  35  or return to the top side of the stopper  35 . The whole operation is the same as that of FIGS. 2,  3 ,  4 , and  5 . From the above description, the serial operation of the contact control device  40 , the push device  60 , and the alloy piece  70  causes the elastic contact plate  80  to rapidly escape to cut off the power source and return to a specific state preparing for the next ON state. Accordingly, the whole operation is quick and the structure of the power switch is simple without any risk of false operation. 
     Although only the preferred embodiments of this invention were shown and described in the above description, it is requested that any modification or combination that comes within the spirit of this invention be protected.