Abstract:
A push-button switch having an overload protection function and a circular type actuation mechanism is disclosed. The switch comprises a conduction lead to be actuated by circularly rotating actuators. The actuators rotate in response of each sliding cycle of the button. Thus, a switch that occupies least space, reduces wearing and increases lifetime, is obtained.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a push-button switch, in particular, to a push-button switch having an overload protection function and a circular type actuation mechanism, in which a rotatable actuator is used to circularly actuate the connection of terminals so as to obtain a simple structure and a small volume. 
     2. Description of the Related Art 
     There are many types of push-button switches for various applications, such as one having a turn-on indicating lamp and one providing an overload protection function. As to one having an overload protection function, there are also several kinds of protection principles or mechanisms being adopted. For example, both the blowout of a fuse wire and the thermal deformation of a bimetal blade have ever been adopted as a trigger source for an overload protection. However, the fuse wire is not repetitive and thus its utility rate gradually decreases. As for the thermal bimetal blade, there are many kinds of mechanism, such as those disclosed in U.S. Pat. Nos. 5,786,742, 5,223,813, 4,937,548, 4,661,667, 4,931,762, 5,451,729, and 4,704,594. 
     Moreover, there has been disclosed a conventional switch in which a slide-to-rotate mechanism comprising a push-button and a rotatable slider is used. One end of the rotatable slider is installed with a pair of conduction pads for alternatively contacting with and thus conducting two terminals in the switch in response to the rotation of the slider. However, the contacts of such a kind of switch wear very soon due to the spark resulting form the friction between the conduction pads and the terminals. Moreover, such a kind of switch is not provided with a function of overload protection and thus does not meet the modern requirement of safety. 
     BRIEF SUMMARY OF THE INVENTION 
     The main object of the present invention is to provide a push-button switch having an overload protection function and a circular type actuation mechanism, which has a simple structure and occupies a small space. 
     To achieve its objects above, this invention provides a push button switch comprising a housing, an actuating mechanism, and a circuit mechanism with overload protection, wherein; 
     the housing is provided with a mechanism accommodation chamber and a button guide; 
     the actuating mechanism comprising: 
     a button having an upper end and a lower end as well as a cavity at its lower end guided by the button guide in sliding, 
     a transferring slider having an upper end slipped into the cavity of the button such that it can be rotated at a predetermined angle in response to the sliding of the button, a lower end, and a longitudinal recess opening to the lower end; 
     a push rod having an upper end slipped into the recess of the transferring slider such that it can be rotated along with the rotation of the transferring slider, a lower end, and a pair of first actuators located between the upper and the lower ends for actuating the circuit mechanism in response to the rotation of the transferring slider; 
     a biasing spring forcing the button and the transferring slider up; and 
     the circuit mechanism including a first terminal, a second terminal, and a conduction element for alternatively connecting the first and the second elements in response to the action of the pair of first actuators and disconnecting the first and the second elements in response to overload. 
     By means of the above structure, since the switch is turned on/off by a slide-to-rotate mechanism, and the circuit mechanism can provide an over-load protection function, the switch will have a compact volume, reduce wearing, and thus increase lifetime thereof. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     Following are preferred embodiments of the present invention described in detail in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an exploded schematic perspective view of a push-button switch having an overload protection function and a circular type actuation mechanism in accordance with a first embodiment of this invention; 
     FIG. 2 is an assembled elevation view partly in section of the push-button switch of FIG. 1 in an ON status; 
     FIG. 3 is a view similar to FIG. 2 but in a trip status; 
     FIG. 4 is a view similar to FIG. 2 but in an OFF status; 
     FIG. 5 is an exploded schematic perspective view of a push-button switch having an overload protection function and a circular type actuation mechanism in accordance with a second embodiment of this invention; 
     FIG. 6 is an assembled elevation view partly in section of the push-button switch of FIG. 5 in an ON status; 
     FIG. 7 is a view similar to FIG. 6 but in a trip status before the pressing stem returns to its reset position. 
     FIG. 8 is a view similar to FIG. 6 but in an OFF status; 
     FIG. 9 is an exploded schematic perspective view of a push-button switch having an overload protection function and a circular type actuation mechanism in accordance with a third embodiment of this invention; 
     FIG. 10 is an assembled elevation view partly in section of the a push-button switch of FIG. 9 in an ON status; 
     FIG. 11 is a view similar to FIG. 10 but in a trip status before the pressing stem returns to its reset position; 
     FIG. 12 is a view similar to FIG. 11 but in an OFF status; 
     FIG. 13 is an exploded schematic perspective view of a push-button switch having an overload protection function and a circular type actuation mechanism in accordance with a fourth embodiment of this invention; 
     FIG. 14 is an assembled elevation view partly in section of the push-button switch of FIG. 13 in an ON status; 
     FIG. 15 is a view similar to FIG. 14 but in a trip status before the pressing stem returns to its reset position; 
     FIG. 16 is a view similar to FIG. 14 but in an OFF status; 
     FIG. 17 is an exploded schematic perspective view of a push-button switch having an overload protection function and a circular type actuation mechanism in accordance with a fifth embodiment of this invention; 
     FIG. 18 is an assembled elevation view partly in section of the push-button switch of FIG. 17 in an ON status; 
     FIG. 19 is a view similar to FIG. 18 but in a trip status before the pressing stem returns to its reset position; and 
     FIG. 20 is a view similar to FIG. 18 but in an OFF status. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Following is a push-button switch having an overload protection function and a circular type actuation mechanism in accordance with some preferred embodiments of this invention described in reference to the drawings. 
     FIGS. 1 to  4  show a push-button switch  100  having an overload protection function and a circular type actuation mechanism in accordance with a first preferred embodiment of the present invention. As shown in FIG. 1, the push-button switch  100  comprises a housing  110 , an actuating mechanism  120 , and a circuit mechanism  130 . The housing  110  is comprised of a front shell  111  and a back shell  112  by which a lower mechanism accommodation space  113  and an upper button guider  114  are defined therein. 
     The actuating mechanism  120  comprises a button  121  being able to slide in the button guider  114  and having an upper end, a lower end, and a cavity opening to the lower end, a transferring slider  122  slipped into the cavity of the button with one end and being able to be rotated at a predetermined angle in response to the sliding of the button  121 , a push rod  123  slipped into the transferring slider with one end and being able to rotate along with the rotation of the transferring slider, and a biasing spring  123  for biasing the button  121  and the transferring slider  122  up. The push rod  123  includes in longitude a square pillar  123   a  at upper portion, a disk  123   b  at middle portion, and a stand leg  123   c  at lower portion. The disk  123   b  is provided with a pair of actuators  123   d  longitudinally extending downward from the opposite portions of the periphery of the disk  123   b . Each of the two actuators  123   d  is provided with a tapered lower end facing the rotation direction of the push rod  123 . The structure and relationship between the button guider  114 , button  121 , the transferring slider  122 , and the biasing spring  124  are similar to the configuration of a push-type extension ball pen, except that a square recess  122   a  opening to the lower end of the transferring slider  122  is provided therein for receiving and rotating the square pillar  123   a  of the push rod  123 . The biasing spring  124  is installed between the disk  123   b  of the push rod  123  and the transferring slider  122  so as to bias the stand leg  123   c  of the push rod  123  downward to rest on a button wall of the mechanism accommodation space  113 , and to bias the transferring slider  122  and the button  121  upward. The transferring slider  122  can rotate to four fixed points in a circle and to each fixed point in response to an up-down reciprocation of the button  121 . Thus, each rotation of the transferring slider  122  would be at 90 degree and so would the push rod  123 . 
     Circuit mechanism  130  mainly comprises a first terminal  131  fixed on the housing  110 , a second terminal  132  fixed on the housing  110 , and a conduction element comprising a conduction leaf  133  and a thermal couple  134  located between the first and the second terminals  131  and  132 . The conduction leaf  133  has one end fixed on the housing  110  and the other end for releasably contacting the first terminal  131 . The thermal couple  134  has a fixed end permanently connected to the second terminal  132  and a movable end for releasably contacting the one end of the conduction leaf  133 . The movable end of the thermal couple  134  is loosely coupled by a promoting leaf  135 , which is loosely mounted on the housing  110  and used to promote the escape of the movable end of the thermal couple  134  from the conduction leaf  133  to a trip position in sudden when the circuit mechanism is overloaded and goes to trip, as well as to keep the movable end of the thermal couple  134  in the trip position. The thermal couple  134  and the conduction leaf  133  extend in a direction substantially vertical to each other and vertical to the longitudinal direction of the push rod  123  so that they can be alternatively triggered by the two opposite actuators  123   d , respectively. 
     By means of the above configuration, in case the thermal couple  134  is not overloaded and tripped, the push rod  123  will rotate at 90 degree in response to a single push reciprocation of the button  121 , and the two actuators  123   d  will alternatively and discontinuously pass over the thermal couple  134  and push the conduction leaf  133  into a conduction position contacting with the first terminal  131 . Thus, the conduction leaf  133  will be alternatively located at a conduction position contacting the first terminal  131  and the thermal couple  134  and an open position escaping from the first terminal  131 , and thus make the switch alternatively into an ON state as shown in FIG.  2  and an OFF (reset) state as shown in FIG.  4 . 
     Since the two actuators  123   d  are opposite to each other at 180 degree and thus the thermal couple  134  will not be pushed when the conduction leaf  133  is pushed by one of the actuators  123   d . In case the circuit mechanism is overloaded, thus, the thermal couple  134  will trip to a trip position and thus make the circuit mechanism into an open-circuit state as shown in FIG. 3 even though the conduction leaf  133  is in a conduction position. 
     When the thermal couple tripped, by means of the promoting leaf  135 , the thermal couple  134  will be kept at its trip position even after being cold down. Once the button  121  is pushed, the push rod  123  will rotate at 90 degree and the other one of the actuators  123   d  will push the thermal couple back to its normal position, as shown in FIG. 4, in which the one end of the conduction leaf  133  is contacted, while the one of the actuators  123   d  will release the conduction leaf  133  into an open position. Thus, the first terminal  131  and the second terminal  132  still fail to conduct each other and the switch  100  is in an OFF (reset) state. However, if the button  121  is pushed once again, the conduction leaf  133  will be pushed by the actuator  123   d  into a conduction position again and make the switch into an ON state due to the fact that the thermal couple  134  has been in a normal position. 
     According to the above, the switch  100  will be circularly turned ON or OFF and is provided with overload protection function occupying a small space. 
     FIGS. 5 to  8  show a push-button switch  200  having an overload protection function and a circular type actuation mechanism in accordance with a second preferred embodiment of the present invention. As shown in the explored perspective view of FIG. 5, the push-button switch  200  comprises a housing  210 , an actuating mechanism  220 , and a circuit mechanism  230 . The arrangement of the housing  210  and the actuating mechanism  220  is substantially the same with that in the first embodiment and thus its details are omitted herein. 
     The circuit mechanism  230  is similar to that in the first embodiment and comprises an isolating blade  235  and a biasing spring  236  as well as a first terminal  231  fixed on the housing  210 , a second terminal  232  fixed on the housing  210 , and a conduction element comprising a conduction leaf  233  and a thermal couple  234  located between the first and the second terminals  231  and  232 . The shape of the thermal couple  234  is different from that in the first embodiment. The isolating blade  235  is located between a pad at a movable end of the thermal couple  234  and a pad at one end of the conduction leaf  233 , and is slidably mounted on the housing  210  such that it can be biased by the biasing spring  236  toward an isolating position in which the pads of the thermal couple  234  and the conduction leaf  233  are separated. Moreover, the isolating blade  235  is provided with a tab  235   a  to be pushed by the actuators  223   d  and a notch  235   b  for the pass of the pad of the thermal couple  234  so as to be contacted by the pad of the conduction leaf  233 . 
     In the second embodiment, in normal state, the actuator  223   d  will alternatively and discontinuously push the conduction leaf  233  into a conduction position, i.e., ON state, as shown in FIG. 6, at which the first terminal is electrically contacted, and an open position, i.e., OFF state. As to the thermal couple  234 , its pad in normal state will pass through the notch  235   b  and be in contact with the pad of the conduction leaf  233  if the isolating blade  235  is pushed by the actuator  223   d  on its tab  235   a  into a pass position. In such a pass position, the movement of the isolating blade  235  into an isolating position is prevented. This is because in such a pass position the pad of the thermal couple  235  will rest on the sidewall of the pad of the conduction leaf  233  and thus they themselves resist the forward moving of the isolating blade  235  under counteracting the biasing spring  236 . 
     When the circuit mechanism is overloaded, the thermal couple  234  will be deformed and thus the pad thereof separates away from the pad of the conduction leaf  233 . Thus, under the action of the biasing spring  236 , the portion of the isolating blade  235  which surrounds the notch  235   b  will move into the gap formed between the pads of the thermal couple  234  and the conduction leaf  233 , and thus into the isolating position, as shown in FIG. 7, in which the two pads are separated thereby. Subsequently, even if the thermal couple  234  is cold down and recovers to its normal state, the circuit mechanism will keep open-circuit. This is because the isolating blade  235  will be interposed between the pads of the thermal couple  234  and the conduction leaf  233  if the button is not pushed again. 
     For resetting the switch  200 , the button  221  should be pushed down once after overload. Meanwhile, the actuator  223   d  is rotated and pushes the tab  235   a , under counteracting the biasing spring  236 . Thus, the isolating blade  235  will be in a pass position in which the pads of the thermal couple  234  and the conduction leaf  233  go through the notch  235   b  and contact each other. Under such a contact, the two pads will not be pushed away by the isolating blade  235 . Thus, thermal couple  234  contacts the conduction leaf  233  and the reset operation is finished. However, since the conduction leaf  233  is not pushed down by any actuator  223   d , the circuit mechanism will be circuit-opened, as shown in FIG.  8 . However, if the button  221  is pushed down twice, the switch  200  will return to an ON state as shown in FIG.  6 . 
     FIGS. 9 to  12  show a push-button switch  200  having an overload protection function and a circular type actuation mechanism in accordance with a third preferred embodiment of the present invention. As shown in the explored perspective view of FIG. 9, the push-button switch  300  comprises a housing  310 , an actuating mechanism  320  and a circuit mechanism  330 . The configuration of the housing  310  and the actuating mechanism  320  is similar to that in the first embodiment except for the push rod  323 . The push rod  323  comprises, in longitude a square pillar  323   a  at upper portion two disks  323   b  and  323   d  spaced longitudinally at middle portion, and a stand leg  323   c  at lower portion. The two opposite portions of the disks  323   b  and  323   d  in peripheral are respectively provided with a pair of reset actuators  323   e  and a pair of turn-on actuators  323   f  all radially extending outward. The two pairs of actuators are staggered at right angle around the periphery of the push rod  323 . 
     The circuit mechanism  330  is similar to that in the first embodiment except that the thermal couple  334  and the conduction leaf  333  extend in parallel and are located in a position respectively corresponding two disks  323   b  and  323   d  so that they can be pushed thereby. A conduction strip  337  is additionally provided so as to conduct movable ends of the thermal couple  334  and the conduction leaf  333 . Moreover, the fixed end of the conduction leaf  333  is connected with the first terminal  331 . The fixed end of the thermal couple  334  is connected with the second terminal  332 . The longitudinal axis of the push rod  323  is vertical to the extending directions of the thermal couple  334  and the conduction leaf  333 . 
     By means of the third embodiment, the turn-on actuators  323   f  and the reset actuators  323   e  will be alternatively located in an actuating position, i.e., a position capable of pushing either the thermal couple  334  or the conduction leaf  333  down into a conduction position, in response to each rotation of the push rod  323 . Thus, the conduction leaf  333  will be actuated one time to an ON state as shown in FIG. 10 per twice of pushing button. If the circuit mechanism is overloaded during ON state, the thermal couple  334  will be deformed to a trip position and make the switch into an open state as shown in FIG. 11 because the reset actuator  323   e  is not in a position to push the thermal couple  334 . In such an open state, the turn-on actuator  323   f  will leave from its actuating position and the reset actuator  323   e  will push the thermal couple  334  back into its reset position, i.e., conduction state, once the button  321  is pushed down. Thus, conduction leaf  333  is in an open position and the thermal couple  334  is in conduction position, and thus the circuit mechanism  330  comes into a reset state, i.e., OFF state, as shown in FIG. 12, 
     FIGS. 13 to  16  show a push-button switch  400  having an overload protection function and a circular type actuation mechanism in accordance with a fourth preferred embodiment of the present invention. As shown in the explored perspective view of FIG. 13, the push-button switch  400  also comprises a housing  410 , an actuating mechanism  420 , and a circuit mechanism  430 . The arrangement of the housing  410  and the actuating mechanism  420  is substantially the same with that in the third embodiment and thus its details are omitted herein. 
     The circuit mechanism  430  is similar to that in the third embodiment except having a thermal couple  434  similar to that in the second embodiment. That is, the thermal couple  434  is similar to the thermal couple  234  except that one end of the thermal couple  434  is fixed onto the conduction strip  437  while the other end thereof gets in touch with the second terminal  432  movably. Moreover, the circuit mechanism  430  includes an isolating blade  435  and a biasing spring  436  like in the second embodiment. The isolating blade  435  is located between a pad at one end of the thermal couple  434  and a pad at one end of the conduction leaf  433  and is slidably mounted on the housing  410  such that it can be biased by the biasing spring  436  toward an isolating position in which the pads of the thermal couple  434  and the conduction leaf  433  are separated. Moreover, the isolating blade  435  is provided with a tab  435   a  to be pushed by the actuators  423   e  into a pass position and a notch  435   b  for allowing the pad of the thermal couple  434  to pass there through to contact the pad of the conduction leaf  433 . The conduction leaf  433  has one fixed end permanently connected to the first terminal  431  and a movable end for contacting the conduction strip  437 . 
     By means of the above structure, once the push rod  423  is rotated at 90 degree, the turn-on actuator  423   f  and the reset actuator  423   e  will be in actuating position in turns. Thus, the conduction leaf  433  will be pushed into an ON state as shown in FIG. 14 per twice of pushing the button  421 . When the circuit mechanism is overloaded during ON state, the thermal couple  434  will go into a trip position and the isolating blade  435  will go into an isolating position by the fact that in that meanwhile the thermal couple  434  is not pushed down by the reset actuator  423   e . Accordingly, the switch  400  is circuit-opened and goes into an OFF state as shown in FIG.  15 . Consequently, if the button  421  is pushed again, the turn-on actuator  423   f  will leave from its actuating position and the reset actuator  423   e  will push the tab  435   a  of the isolating blade  435  so as to make the isolating blade  435  go into a pass position from the isolating position. In the pass position, the pads of the thermal couple  434  and the second terminal  432  will pass through the notch provided in the isolating blade  435  and electrically contact together. Thus, the switch  400  goes into a reset (OFF) state as shown in FIG. 16 in which the thermal couple  434  is closed and the conduction leaf  433  is open. 
     FIGS. 17 to  20  show a push-button switch  500  having an overload protection function and a circular type actuation mechanism in accordance with a fifth preferred embodiment of the present invention. As shown in the explored perspective view of FIG. 17, the push-button switch  500  comprises a housing  510 , an actuating mechanism  520  and a circuit mechanism  530 . The configuration of the housing  510  and the actuating mechanism  520  is similar to that in the first embodiment except for the push rod  523 . The push rod  523  comprises in longitude a square pillar  523   a  at upper portion and a stand leg  523   c  at lower portion, as well as a pair of turn-on actuators  523   f  and a pair of isolating actuators  523   e  substantially at the middle portion. The turn-on actuator  523   f  is of a shape of plate while the isolating actuators  523   e  is of a shape of a right triangular section bar having a slope facing its rotation direction. The two pars of actuators are staggered at right angle around the periphery of the push rod  523  in substantially the same plane. 
     The circuit mechanism  530  is similar to that in the second embodiment except that the so-called conduction element is comprised of a thermal couple  534  only. Moreover, an isolating blade  535  is not provided with a notch like in the second embodiment. In detail, the thermal couple  534  of the circuit mechanism  530  has one end being permanently connected to a first terminal  531  and a movable end for contacting a second terminal  532 . The isolating blade  535  can be pushed by a biasing spring  536  into an isolating position in which the movable end of the thermal couple  534  is isolated from the second terminal  532 . The isolating blade  535  is provided with a tab  535   a  extending into a space being able to be actuated by the turn-on actuator  523   f  into a pass position in which the thermal couple  534  is connected with the second terminal  532 . Moreover, the isolating actuator  523   e  is provided on the push rod  523  such that it can push an edge  534   a  of the thermal couple  534  during its rotating course so as to make the thermal couple depart from the second terminal  532 . 
     By means of the above structure, once the button  521  rotates the push rod  523  at 90 degree so as to force the turn-on actuator  523   f  to push the isolating blade  535  into a pass position departing from the pads of the thermal couple  534  and the second terminal  532 , those two pads will contact each other and thus the switch  500  is turned ON. It is understood that a peripheral end  535   b  of the isolating blade  535  will rest on the side surfaces of the pads of the thermal couple  534  and the second terminal  532 , as shown in FIG. 18, after the turn-on actuator  523   f  rotates, pushes and passes over the tab of the isolating blade  535  and into a fixed point. In other words, the tab  535   a  is not always pushed by the turn-on actuator  523   f.    
     Under the above turn-on state, the isolating actuator  523   e  will push the side edge  534   a  of the thermal couple  534  if the button  521  is pushed once. Thus, a gap will come out between the pads of the thermal couple  534  and the second terminal  532  so as to allow the isolating blade to slide thereunto, under the biasing of the biasing spring  536 , to an isolating position and thus to separate those two pads. Thus, a reset state, i.e., OFF state, as shown in FIG. 20 is obtained. However, it should be noted that the status in FIG. 20 shows the process when the isolating actuator  523   e  is pushing the thermal couple  534  away from the second terminal  532 . 
     In case the circuit is overloaded, the thermal couple  534  will be deformed and thus depart away from the second terminal  532 . Therefore, a gap is formed between the pads of the thermal couple  534  and the second terminal  532  and thus the isolating blade slides into the gap and isolates those two pads. The switch  500  is thus circuit-opened and into a configuration as shown in FIG.  19 . After such an overload, the isolating blade  535  will keep those pads being isolated even the thermal couple  534  is cold down and returns to its normal status. In the next rotation of the push rod  523 , what passes through those pads will be the isolating actuator  523   e  rather than the turn-on actuator  523   f , and thus such a rotation makes the switch  500  enter into a stand-by state to be turned on. Thus, after overload, a twice pushing is necessary to turn on the switch  500 , and the isolating actuator  523   e  also functions as a reset actuator to reset the switch  500  after overload. 
     In sum, while the present invention is described by way of preferred embodiments, it is understood that the embodiments are used only to illustrate the technical concept of the present invention without limiting the scope thereof. It is therefore intended to show that all modifications and alterations that are readily apparent to those skilled in the art are within the scope as defined in the appended claims.