Patent Publication Number: US-2016233041-A1

Title: Switch module of built-in anti-surge disconnection structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a switch module of built-in anti-surge disconnection structure, particularly to an overcurrent protection switch that has anti-surge and disconnection structures built inside. 
     2. Description of the Related Art 
       FIGS. 1A and 1B  disclose a conventional overcurrent protection switch  10 , comprising a housing  11  with a press button  12  on the top, a first terminal  12   a , a second terminal  12   b , a third terminal  12   c  separately arranged at the bottom, and a moving element  14 . The first terminal  12   a  has a bimetal plate  13  and a first contact  131 ; the second terminal  12   b  has a second contact  121  corresponding to the first contact  131 . The moving element  14  has one end linking the bottom of the press button  12  and the other linking the moving terminal of the bimetal plate  13 , whereby the pressing of the press button  12  actuates the first contact  131  connecting to the second contact  121  and therefore turns on the device; while overcurrent occurs, the bimetal plate  13  deforms due to high degree of temperature and disconnects the first and second contact  131 ,  121 , turning off the device so as to form an overcurrent protection switch  10 . Such structure can be found in Taiwan patent applications No. 540811, 367091, 320335, 262168, and 208384. However, the structure disclosed above aims at protection from overcurrent situation but is not able to protect the device when sudden overvoltage such as lightning stroke occurs. 
     Therefore, for safety concern, a usual solution to the defect is to parallel connect to a metal oxide varistor, and to connect to a thermal fuse in series. 
       FIG. 2  is the invention of U.S. Pat. No. 8,643,462. It discloses an anti-surge switch module applied in an electric system. The switch module comprises a power switch  105 , an insulating member  106 , a surge absorber  107  and a pyrocondensation belt  108 . The insulating member  106  engages with the power switch  105  that abutting against the surge absorber  107 ; and the pyrocondensation belt  108  ties the surge absorber  107  and the insulating member  106  together so that it could contract when receiving the heat from the surge absorber  107  and thus turn off the power switch  105  under certain degree of contracting. However, the insulating member  106 , the surge absorber  107  and the pyrocondensation belt  108  are not disposed inside the power switch  105  but are connected outside, failing to form a complete device with the power switch  105 . 
     In short, the structures disclosed above have shortcomings as uncertain quality, possible exceeding heat, slow reaction, large volumes, and complicated composition, and they require more constructing space and procedures. Besides, the protection device has to be connected independently outside instead of having one inside. 
     In UL 1449 3 rd  Edition (2009) Type 4 was added to Surge Protective Devices (SPDs) requirements. The 3 rd  Edition also includes the Low voltage Surge Arrestres under 1000 V in the requirements, and the title is also altered from Transient Voltage Surge Suppressors into Surge Protective Devices. This shows the importance of the components being integrated and the surge arrestres function of the device. 
     Hence, it is desirable to construct an anti-surge disconnection structure built inside a heat-resisting and fireproof housing of an overcurrent protection switch  10  so that the disconnection could be operated successfully and instantly when an overload occurs. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide a switch module of built-in anti-surge disconnection structure that has the original function of overcurrent protection and further includes the anti-surge and disconnection features to ensure more of electricity safety. 
     Another object of the present invention is to have the anti-surge disconnection structure built inside the switch module for more safety and easy assembly with other electronic devices. 
     To achieve the objects mentioned above, the present invention comprises a housing with a press button at the top thereof, a first conductive plate arranged at the lower section thereof as the positive electrode for input, a second conductive plate as the positive electrode for output and a third conductive plate as the negative electrode for input, where said first conductive plate is connected to a binary alloy conductive plate that has a spring leaf and a first connecting point in the middle section thereof, and said second conductive plate has a second connecting point on the surface thereof corresponding to said first connecting point; a moving rod linking up the bottom of said press button with one end and a movable end of said binary alloy conductive spring leaf with the other end, whereby the press button would press said binary alloy conductive plate and the spring leaf thereon to connect the first connecting point with the second connecting point, turning on the switch, and when current overload occurs, the binary alloy conductive plate would deform due to high temperature, detaching said first connecting point on the spring leaf from the second connecting point, thus turning off the switch, so as to form an overcurrent protection switch; wherein 
     an anti-surge disconnection structure is built inside the housing under the spring leaf, including: at least one metal oxide varistor with a top surface and a bottom surface, and a set of conductive elements; a spring disposed on either surface of the metal oxide varistor; a band having a first end and a second end arranged closely and correspondingly to compress the spring on the metal oxide varistor; at least one thermo-sensitive piece that is solid colloid to be adhered on the surface of the metal oxide varistor and to bond the first end and the second end for fixing the spring; a pushing rod disposed under the bottom of the spring leaf; 
     whereby when the first connecting point is contacting the second connecting point and an overvoltage occurs, the temperature of said metal oxide varistor would suddenly rise up to a pre-determined degree and the thermo-sensitive piece would melt, then the band would loosen, counterbalancing the compressing force on the spring and further displacing the pushing rod upwardly, therefore forcing the first connecting point detaching from the second connecting point and turning off the switch without having the binary alloy conductive plate deformed or being displaced. 
     In addition, the thermos-sensitive is made of non-metal thermo-sensitive materials or metal compounds that are fast-acting in low temperature. 
     As structures disclosed above, the present invention complements the defect of a conventional overcurrent protection switch that it has to connect to a metal oxide varistor from the outside by having an anti-surge disconnection structure ingeniously built inside the heat-resisting and fireproof housing. When receiving exceedingly high voltages, the heating metal oxide varistor would instantly melt the thermo-sensitive piece down, loosening the band, counterbalancing the compressing force on the spring and further displacing the pushing rod upwardly, therefore forcing the first connecting point detaching from the second connecting point and turning off the switch immediately. Therefore, the present invention is not only overcurrent protective but also overvoltage protective and surge absorbing, ensuring more electricity safety and conveniences in using. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of an overcurrent protection switch according to the prior art; 
         FIG. 1B  is a section view of an overcurrent protection switch according to the prior art; 
         FIG. 2  is a perspective view of an anti-surge and disconnection structure according to the U.S. Pat. No. 8,643,462; 
         FIG. 3  is a sectional view of the present invention in a preferred embodiment in an OFF status; 
         FIG. 4  is a sectional view of the present invention in a preferred embodiment in an ON status; 
         FIG. 4A  is a sectional view of line  4 A- 4 A in  FIG. 4 ; 
         FIG. 5  is an application example of the present invention illustrating the thermo-sensitive piece melting, loosening the band and displacing the pushing rod, further turning the switch off; 
         FIG. 5A  is a sectional view of line  5 A- 5 A in  FIG. 5 ; 
         FIG. 6  is an exploded view of the major components of the present invention in a preferred embodiment; 
         FIG. 7A  is a schematic diagram of the present invention with two metal dioxide varistors; 
         FIG. 7B  is a schematic diagram of the present invention with three metal dioxide varistors; 
         FIG. 8  is a top perspective view of the present invention in a preferred embodiment; and 
         FIG. 9  is a bottom perspective view of  FIG. 8   
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 3-6 , a preferred embodiment of the present invention comprises a housing  31  with a press button  32  at the top thereof, a first conductive plate  40  arranged at the lower section thereof as the positive electrode for input, a second conductive plate  50  as the positive electrode for output and a third conductive plate  60  as the negative electrode for input; the first conductive plate  40  is connected to a binary alloy conductive plate  41  that has a spring leaf  42  and a first connecting point  421  in the middle section thereof, and the second conductive plate  50  has a second connecting point  511  on the upper section  51  thereof corresponding to said first connecting point  421 . 
     Also, it comprises a moving rod  33  linking up the bottom of said press button  32  with the top end thereof and a movable end  411  of said binary alloy conductive plate  41  with the bottom end, whereby the press button  32  would press said binary alloy conductive plate  41  to connect the first connecting point  421  with the second connecting point  511 , forcing the spring leaf  42  to move downwardly and turning on the switch as illustrated in  FIGS. 4 and 4A . When current overload occurs, the binary alloy conductive plate  41  would deform due to high temperature and leading the present invention back to the off status illustrated in  FIG. 3 . The first connecting point  421  is therefore detached from the second connecting point  511 , turning off the switch, so as to form a switch module  30  comprised mainly by an overcurrent protection switch. However, such structure belongs to the prior art already. 
     The features of the present invention lies in the upper section  51  of the second conductive plate  50  having a gap  52  near the side of the second connecting point  511  in an applicable embodiment, and an anti-surge disconnection structure  70  being built inside the housing  31  under the spring leaf  42 , including at least one metal oxide varistor  71 , a spring  73 , a band  74 , at least one thermo-sensitive piece  72 , and a pushing rod  75 . 
     The metal oxide varistor  71  has a top surface and a bottom surface  711 , and a set of conductive elements  712 ; the conductive elements  712  can be a conductive wire, a flexible piece, or an element extended from the metal oxide varistor  71 . 
     The spring  7   3  is disposed on the top surface  71   1  of the metal oxide varistor  71 . The band  74  compresses the spring  73  on the metal oxide varistor  71  with a first end  741  and a second end  742  arranged correspondingly, making it stayed in a shorter length than usual; it can be a banding, a cord, or a string. 
     The thermo-sensitive piece  72  is a solid colloid to be adhered on the surface of the metal oxide varistor  71  and to bond the first end  741  and the second end  742  for girdling and fixing the spring  73 . In the embodiment, it can be made of non-metal thermo-sensitive materials or metal compounds that are fast-acting in low temperature, but is not limited to such application. In other words, the materials that would melt in certain degree which is lower than the high degree the metal dioxide varistor  71  would reach would work, whether conductive or not. Such compounds have firm melting point and the feature of fast-acting. On the other hand, the band  74  and the thermo-sensitive piece  72  are made of either metal or non-metal materials; for instance, a non-metal band  74  combing with a metal thermo-sensitive piece  72  would work, or both of them are made of the same thermo-sensitive materials. Such structure is already well known in the field. 
     The pushing rod  75  has the upper end thereof being disposed through the gap  52  of the upper section  51  of the second conductive plate  50 , under the bottom of the spring leaf  42  when the first connecting point  421  of the spring leaf  42  is contacting the second connecting point  511 . In this embodiment, it further includes a bottom  751  to be disposed against the top of the spring  73  but is not limited to such application; the pushing rod  75  having a wider contacting area than the top surface of the spring  73 , or being combined or fixed with the spring  73  for synchronous upward displacement would be workable. The main function of the pushing rod  75  is to push and displace the spring leaf  42 , and force the first connecting point  421  detaching from the second connecting point  511  when the switch module  30  is in unusual status. 
     Further referring to  FIGS. 5 and 5A , when the first connecting point  421  is contacting the second connecting point  511  and an overvoltage occurs, the temperature of said metal oxide varistor  71  would suddenly rise up to a degree higher than the melting point of the thermo-sensitive piece  72 , and the thermo-sensitive piece  72  would melt, then the band  74  would loosen, counterbalancing the compressing force on the spring  73  and further displacing the pushing rod  75  upwardly, therefore forcing the first connecting point  421  detaching from the second connecting point  511  and turning off the switch without having the binary alloy conductive plate  41  deformed or being displaced. 
       FIG. 6  is an exploded view of the main elements of the present invention. The anti-surge disconnection structure  70  mainly comprises at least one metal oxide varistor  71 , at least one thermo-sensitive piece  72 , at least one spring  73 , at least one band  74 , and a pushing rod  75 . Meanwhile, with reference to  FIGS. 3-5 , the anti-surge disconnection structure  70  is arranged between the first conductive plate  40  and the second conductive plate  50 . In the embodiment, the housing  31  has a vertical holding surface  34  and a horizontal positioning surface  35  arranged therein for the upper section  51  of the second conductive plate  50  to be disposed on the positioning surface  35 , and the positioning surface  35  has a passage  36  arranged corresponding to the gap  52  of the upper section  51  for the pushing rod  75  to pass through. Furthermore, the housing  31  has two corresponding narrow grooves  37  arranged between the first and second conductive plates  40 ,  50  for both sides of the metal oxide varistor  71  to be engaged in position, so that the entire anti-surge disconnection structure  30  is steadily built inside the housing  30 . 
     When an overvoltage occurs to the switch module  30  of the present invention, the temperature of the metal oxide varistor  71  instantly rises up to a pre-determined degree, melting the thermo-sensitive piece  72  on the upper surface  711  of the metal oxide varistor  71 . A metal oxide varistor is an non-ohmic conductive component. The electric resistance of a metal oxide varistor depends on the external voltages. Therefore, the V-I characteristic curve of it is obviously non-linear, making it popularly used in the practical field for preventing the power supply system from the damages caused by sudden overvoltage. The thermo-sensitive piece  72  of the present invention would melt immediately when an overvoltage occurs and results in the instant rising of temperature of the metal oxide varistor  71 , loosening the band  74 , counterbalancing the compressing force on the spring  73  and further displacing the pushing rod  75  upwardly, therefore forcing the first connecting point  421  detaching from the second connecting point  511  and turning off the switch in a short time without having the binary alloy conductive plate  41  deformed or being displaced. 
     In the disclosed embodiment, there is one metal oxide varistor  71  but it is not limited to such application. In  FIG. 7A , the present invention includes two parallel connected metal oxide varistors  71   a ,  71   b  to be combined with the band  74 , enhancing the anti-surge function and enabling more rapid melting of the thermo-sensitive piece  72  with two heating surfaces when an overvoltage occurs. This also ensures more safety. Apart from this structure, in an applicable embodiment, one of the metal oxide varistors  71   a ,  71   b  could be connected to the ground with an end as well; in this way, there is another protection structure for the present invention. 
       FIG. 7B  illustrates the present invention including three metal oxide varistors  71   a ,  71   b ,  71   c  to be combined with the band  74  for a three-wire circuit protection. The difference between the embodiments disclosed above is that a first thermo-sensitive piece  72   a  is fixing the first end  741  of the band  74  between the first and the second metal oxide varistors  71   a ,  71   b , and a second thermo-sensitive piece  72   b  is fixing the second end  742  of the band  74  between the second and the third metal oxide varistors  71   b ,  71   c . Each metal oxide varistor is connected to the live wire, neutral wire, and ground wire individually so that when an overvoltage occurs to any of which, it is able to disconnect the circuit. In addition, it is also applicable to parallel connect three metal oxide varistors for triple anti-surge and apply in two-wire circuit. In sum, the present invention may include one or more metal oxide varistors inside the housing  31 . 
       FIG. 8  is a top perspective view of the present invention in a preferred embodiment. In the embodiment, the housing  31  further includes a display unit  38  on the outside. After the thermo-sensitive piece  72  in the switch module  30  melted and turned it off, the display unit  38  would show the status of the switch module  30  by a LED bulb or a block; also, it is applicable to have the pushing rod  75  pushing the other negative electrode for simultaneously separating both the positive and negative electrodes and disconnect. Such structures can be easily achieved by a person who is familiar with the art. 
       FIG. 9  is a bottom perspective view of  FIG. 8 . In this embodiment, the housing  31  not only has the first conductive plate  40  as the positive electrode for input, the second conductive plate  50  as the positive electrode for output, and third conductive plate  60  as the negative electrode for input, but also has a fourth conductive plate  61  as the negative electrode for output and a fifth conductive plate  62  as the terrestrial pole G for the conductive elements  712  of the metal oxide varistor  71  to connect, so as to enhance the completeness of the present invention. 
     With structures disclosed above, the present invention complements the defect of a conventional overcurrent protection switch that it has to connect to a metal oxide varistor and a thermal fuse from the outside by having an anti-surge disconnection structure  70  ingeniously built inside so that when receiving exceedingly high voltages, the heating metal oxide varistor  71  would instantly melt the thermo-sensitive piece  72 , loosening the band  74 , counterbalancing the compressing force on the spring  73  and further displacing the pushing rod  75  upwardly, therefore forcing the connecting points to detach and turning off the switch immediately. Hence, the present invention has the original function of overcurrent protection and further has the overvoltage protection and anti-surge disconnection structures built inside, ensuring more electricity safety and conveniences in using. 
     Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.