Abstract:
A switch structure comprises a control element, which comprises an alloy piece and a swinging device. The swinging device has an actuating element used to actuate the swinging device when the actuating element is pushed. When the alloy piece is overheated due to overloading of current, it will deform toward the actuating element so as to eject the actuating element, which causes the swing device to swing outwards and is released from the supporting of the stopper in the switch body. Then, the swing device moves towards the original closing position, and the elastic contacting piece is released from the pressing of the swing device to eject upwards. Two joints connected in an electric loop are tripped. The object of rapid response, cutting power source, and safety is therefore achieved.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a switch structure, and more specifically, to a power switch with a simpler structure that 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 and OFF functions 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 wires easily catche the fire. The users can not be aware of such latent danger since overloading and overheating are invisible. Therefore, such improved power switches have been greatly needed to overcome the danger. 
     Some improved power switch of 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, the power switch disclosed in the prior arts includes 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 cuts 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 to be 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 THE INVENTION 
     An object of the present invention is to provide a switch structure comprising a control element, which consists of an alloy piece and a swinging device. The swinging device has an actuating element used to actuate the swinging device when the actuating element is pushed. When the alloy piece is overheated due to overloading by the current, it will deforms toward the actuating element so as to eject the actuating element, which causes the swing device to swing outwards and to be released from the support of the stopper in the switch body. Then, the swing device moves towards the original closing position, and the elastic contacting piece is released from the pressing of the swing device to eject upwards. Two joints connected in an electric loop are tripped. The object of rapid response, cutting power source, and safety is therefore achieved. 
     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 the exploded diagram of the switch structure according to the present invention; 
     FIG. 2 is a sectional view illustrating the OFF state of the switch structure according to the present invention; 
     FIG. 3 is a sectional view illustrating the ON state of the switch structure according to the present invention; 
     FIG. 3 a  shows a schematic diagram illustrating localized mechanics in FIG. 3; 
     FIG. 4 is a sectional view illustrating the operation of the switch structure according to the present invention when the current is overloaded; and 
     FIG. 4 a  shows a schematic diagram illustrating localized mechanics in FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, the switch structure comprises a switch cover body  10 , a contact reed  30 , a switch body  40 , a swing device  60 , an elastic contact piece  70 , and an alloy piece  80 . 
     The switch cover body  10  includes a switch seat  20 . The upper surface of the switch cover body  10  forms a concave cambered surface  11 . Axial holes  12  and buckle holes  13  are formed at the proper positions at the two sides thereof. In the switch seat  20 , two fulcrums  21  and two tenons  22  are installed at positions with respect to the axial holes  12  and buckle holes  13  of the switch cover body  10  to join the switch cover body  10 , which presses in two directions along the fulcrums  21 . A resistor seat  23  is formed at one side of the switch seat  20 . A chip resistor  24  is embedded into the resistor seat  23  as a current limiting resistor of the neon lamp  14  within the switch cover body  10  for indicating that the switch is ON. Each side of the resistor seat  23  is installed with a through hole  25 . The bottom of the switch seat  20  is installed with a triangular piece  26 , which has a supporting rod hole  27 . 
     One end of the contact reed  30  passes through the through hole  25  to contact with the chip resistor  24 . Another end is bent to form s hook  31  so as to firmly combine with the third contact terminal  47  for supporting a dynamic force to recover the switch cover body  10  and for electrically connecting to one pin of the neon lamp  14 . 
     The switch body  40  is a hollow shell with an opening  41 . A stopper  42  and a fixing pillar  43  are installed at proper positions of the inner wall of the shell. The opening  41  at the top thereof is connected to the switch cover body  10 . The bottom of the switch body  40  is installed with a plurality of inserting grooves  44 , which are connected to a first, a second, and a third contact terminals  45 ,  46 , and  47 , respectively. 
     The swing device  60  has an elliptical slot  63  at one end to connect to the fixing pillar  43  of the switch body  40  in order to swing. The bottom forms a convex part  64 , on which a through hole  62  is connected to the supporting rod hole  27  in the switch cover body  12  via a supporting rod  65 . Another end has an axial hole  61 . 
     The swing device  60  is connected to an actuating part  50 , which has a shaft  52  at one end for insertion into the axial hole  61 . Another end of the actuating part  50  is installed with an end part  51 , which extends outwards to form a top push piece  511 . The bottom side of the top push piece  511  presses the top side of the stopper  42  of the switch cover body  40 . 
     Additionally, an elastic element  66  is installed between the swing device  60  and the actuating part  50  to provide a recovery force for the swing device  60  and the actuating part  50 . 
     A round convex part  71  is installed at proper positions of the elastic contact piece  70 . The front end thereof has a contact hole  72 , which is connected to an upper contact  73 . A fixing base  81  and a joint piece (rivet)  81  are used to join alloy piece  80  with one leg of the alloy piece  80  so that alloy piece  80  is located over the first and the second terminals  45  and  46 . 
     The alloy piece  80  has an approximate U shape and is joined with the first terminal  45  by the fixing base  81  and the joint piece (rivet)  81 . The top of the alloy piece  80  pushes the end part  51  of the actuating part  50 . 
     Furthermore, the top end of the second contact terminal  46  has a lower contact terminal  461 , which is connected to another pin of the neon lamp  14  by the elastic conductive element (spring)  15 , so as to form a complete electric loop. 
     The actions of the switch in the present invention include OFF, ON, and Trip, when the current is overloaded. The detailed operation will be described in the following. 
     With reference to FIG. 2, the sectional view illustrates the OFF state of the switch according to the present invention when the OFF state is performed by the user. When the user presses the switch body  10  at the right side, the contact reed  30  will extend coordinated with the action so that the switch body  10  clockwise rotates around the fulcrum  21 , and the supporting rod hole  27  moves along a round arc (right in this embodiment) clockwise around the fulcrum  21  to cause the upper end of the supporting rod  65  to move in the same direction. The supporting rod  65  drives the through hole  62  of the swing device  60  so that one end of the swing device  60  is pulled upwards to make the convex part  64  not to press the round convex part  71  of the elastic contact piece  70 . The elastic contact piece  70  ejects upwards because the pressing force applied by the swing device  60  is released. The upper contact  73  and the lower contact  461  separate apart to make the first contact terminal  45  and the second contact terminal  46  disconnected so as to cut off the power source. At the same time, the neon lamp  14  distinguishes because the second contact terminal  46  has no input power. 
     With reference to FIG. 3, the sectional view illustrates the ON state of the switch according to the present invention. 
     When the user presses the switch body  10 , the contact reed  30  will deform with the action so that the switch body  10  counterclockwise rotates around the fulcrum  21 , and the supporting rod hole  27  moves along a round arc (left in this embodiment) counterclockwise around the fulcrum  21  to cause the upper end of the supporting rod  65  to move in the same direction(upper right). The supporting rod  65  drives the through hole  62  of the swing device  60  so that one end of the swing device  60  is pressed down to make the convex part  64  to press the round convex part  71  of the elastic contact piece  70 . The upper contact  73  of the elastic contact piece  70  contacts with the lower contact  461  of the second contact terminal  46 . The external current then flows through the first contact terminal  45 , the alloy piece  80 , the elastic contact piece  70 , the upper contact  73 , and the lower contact terminal  461  into the second contact terminal  46  to form a complete electric loop as an ON state. 
     The current is conducted to one pin of the neon lamp  14  via the elastic conductive element (spring)  15  after the above electric loop constructed. Another pin of the neon lamp  14  is connected to the third contact terminal  47  through the chip resistor  24  and the contact reed  30  to form an electric loop and the neon lamp  14  lights up to indicate the switch is ON. 
     With reference to FIG. 3 a,  when the switch in ON state, the contact reed  30  is pressed to deform and to store the upwards resilient force  301 . Since the through hole  25  is a force applying point, the fulcrum  21  is an axial center, and the distance from the through hole  25  to the fulcrum  21  is an arm of force, the torque  302  is then generated and the angle  303  which has the supporting rod hole  27  as a top point and two sides composed of the sides from the supporting rod hole  27  to the fulcrum  21  and the through hole  62 , respectively, is slighter greater than 180 degrees. The switch cover body  10  in ON state can be positioned by the upward ejecting force of the elastic contact piece  70 . 
     The swing action of the swing device  60  is implemented by using the elliptic slot  63  to confine the fixing pillar  43  to move upwards or downwards, as shown in FIGS. 2,  3 , and  4 . 
     It should be noted that the above OFF and ON states are normal states for the current to cut off or to conduct, so the bottom side of the top push piece  511  in the actuating part  50  of the swing device  60  is pushed by the top side of the stopper  42  without any action. 
     As shown in FIG. 4, the sectional view of the switch according to the present invention illustrates the schematic diagram of ejecting operation when the current is overloaded. When the current generated is overloaded, the alloy piece  80  will bend towards the actuating part  50  of the swing device  60  due to thermal deformation induced by the current. Then, the end part  51  of the actuating part  50  is pushed to cause the actuating part  50  to rotate around the shaft  52  towards the swing device  60  and the elastic element  66  to contact so that the bottom side of the top push piece  511  extended from the end part  51  escapes from the top side of the stopper  42 . The actuating part  50  and the swing device  60  lose support and fall down. Therefore, the left end of the actuating part  50  connected with the swing device  60  moves downwards and the elliptic slot  63  moves upwards so that the convex part  64  can not press the round convex part  71  by upward sliding and the elastic contact piece  70  can smoothly move upwards to push due to the resilient force stored by bending. The upper contact  73  and the lower contact  461 , thus, separate apart to cut off the power source. 
     As shown in FIG. 4 a,  the angle  303  is about 180 degrees so that the torque  302  can easily overcome the reactive force and the elastic force  301  then moves upwards. If the switch cover body  10  is not applied by any external force, the contact reed  30  will release to eject the switch cover body  10 . Then, the switch cover body  10  clockwise rotates around the fulcrum  21  towards the OFF position ( as shown in FIG. 2) and the swing device  60  moves upwards and restores back to a normal position as the supporting rod  65  inclines(as shown in FIG.  2 ). The alloy piece  80  cools down to the original state. The actuating part  50  installed in the swing device  60  places again the bottom side of the top push piece  511  in the end part  51  of the actuating part  50  over top side of the stopper  42  in the switch body  40  by the resilient force of the elastic element  66  so as to prepare for the next switch operation (as shown in FIG.  2 ). 
     Accordingly, the switch of the present invention uses the alloy piece  80  and the swing device  60  to rapidly respond to the status of the current so as to eject the elastic contact piece  70  to cut off the power source. The switch can automatically recover to the open state under overloaded current. The response of the present invention is rapid and the structure is simple without any error 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.