Patent Publication Number: US-6670727-B2

Title: Timed switch

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a timed switch, and more particularly, to a timed switch, which can be fitted to all sorts of appliances, and can work together with other types of protective switches such as temperature switches to provide double protection so as to prevent accident from happening if the other types of protective switches fail to work properly. 
     Over the years, many protective switches have been developed to satisfy the need for a automatically turning off the appliances, such as timed switches which can turn off the appliances, after they have been actuated for a preselected time such that the appliances will not work too long and cause danger. 
     Other protective switches include temperature switches, which can automatically turn off the appliances when the same overheat. All of these protective switches are easy to use, and prevent many dangerous events from happening but people often neglect to maintain the protective switches while continuing to rely on them just because they are very convenient. An accident is likely to happen when the protective switches break down without anybody being aware of it. 
     Therefore, it would be a good idea to have a timed switch which can be easily fitted to an appliance and connected to the original protective switch of the appliance such that the appliance is provided with double protection. 
     SUMMARY OF THE INVENTION 
     Therefore, it is a main object of the present invention to provide a timed switch, which can be easily fitted to an appliance, and connected to other protective switches of the appliance to provide double protection. And, it is another object of the present invention to provide a timed switch, which is easy to use and doesn&#39;t have the drawbacks of conventional ones. 
     The timed switch of the present invention includes a housing member, first, second, and third connecting legs, a control button, and a circuit board. 
     The housing member has a front part and a rear part. The first connecting leg has a front end contacting portion disposed behind the front part, and have a rear end connecting portion sticking out from the rear part of the housing member for electrical connection with a power supply. 
     The circuit board includes an electromagnet and a timing device. The circuit board is received in the housing member, and is electrically connected to a second connecting leg having a rear end sticking out from the rear part of the housing member. The timing device can make the circuit of the circuit board become open at a preselected time after same has been energized. 
     The third leg has a connecting part having a rear end sticking out from the housing member for electrical connection with the input terminal of an appliance, and a vertical part disposed behind the front part of the housing member; the vertical part has an upper end, and a lower end disposed behind the contacting portion of the first leg, and in front of the electromagnet respectively. The third leg is further electrically connected to the circuit board. 
     The control button has a power-off upper end, and a power-on lower end, and is pivoted to the front part of the housing member at a middle with an upper, and a lower pushing protrusions passing through the front part to abut the upper, and the lower ends of the vertical part. 
     Thus, the appliance can be energized when said power-on end is pushed so as to make the lower end of the vertical part come into contact with the electromagnet plus make the upper end of the vertical part come into contact with the contacting portion of the first leg; the circuit board becomes complete for both the electromagnet, and the timing device to be actuated to attract the lower end of the vertical part thereto, and to automatically turn off the appliance at the preselected time respectively. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood by reference to the accompanying drawings, wherein: 
     FIG. 1 is an exploded perspective view of the timed switch according to the present invention. 
     FIG. 2 is a front view of the timed switch according to the present invention. 
     FIG. 3 is a cross-sectional view of the timed switch according to the present invention. 
     FIG. 4 is another timed switch according to the present invention. 
     FIG. 5 is view of an appliance with the timed switch of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a timed switch of the present invention includes a housing member  1 , a first metallic connecting leg  2 , a control button  18 , a circuit board  4 , a second metallic connecting leg  41 , and a third metallic connecting leg  3 . 
     The housing member  1  has a front part  19 , a rear part (not numbered) and a receiving room  11 ; the rear part is provided with a first elongated gap  15 , a second elongated gap  16  and a third elongated gap  17 . The housing member  1  further has a first separating board  12 , a second separating board  13 , and a third separating board  14  secured to the inner side thereof, the first separating board  12  is arranged below the top of the housing member  1  with a space in between; the second and the separating boards  13  and  14  are arranged such that the space in between is just opposite the third elongated gap  17 . The front part  19  has an upper through hole communicating with a space defined by both the separating boards  12  and  13 , and a lower through hole communicating with a space defined by both the third separating board  14  and the bottom of the housing member  1 . 
     The first connecting leg  2  has a contacting portion  21  at the front thereof, and an engaging gap  22  at the middle part, and is inserted into the first elongated gap  15  with the engaging gap  22  closely mounted on the edge of the inner end of the first elongated gap  15  such that the contacting portion  21  faces the front part  19 , and the rear end portion of first connecting sticks out from the rear part of the housing member for electrical connection to the power supply. 
     The third connecting leg  3  has a horizontal connecting part and a vertical part; the horizontal part has a connecting portion  34  at the front portion and an engaging gap  35  at the middle portion; the middle portion of the vertical part is pivoted to the front end of the horizontal part, and has a contacting portion  33  at the upper end, resilient strip portions  31  sticking frontward therefrom, and an attracted portion  32  at the lower end. The horizontal part of the third connecting leg  3  is inserted into the third elongated gap  17  as well as the space between the second and the third separating boards  13  and  14  with the engaging gap  35  closely mounted on the edge of the inner end of the gap  17  such that the vertical part faces the front part  19  of the housing member  1  in a substantially parallel orientation, and the rear end portion of the third connecting leg  3  sticks out from the rear part of the housing member  1  as an out put terminal. The resilient strips  31  abut the inner side of the front part  19  to keep the upper end contacting portion  33  away from the contacting portion  21  when the power-on end  181  is not pressed to actuate the circuit board  4 . 
     The circuit board  4  has an indicating light  44 , a gap  42  at the middle portion and an electromagnet  43  at the lower end. The second connecting leg  41  is fixed, and electrically connected, to the circuit board  4 , and has an engaging gap  411 . The circuit board  4  joined to the second connecting leg  41  is fitted into the housing member  1  with the engaging gap  411  of the second connecting leg  41  closely mounting on the edge of the inner end of the second elongated gap  16 ; a rear end portion of the second connecting leg  41  sticks out from the rear part of the housing member  1  for electrical connection with the power supply; the gap  42  is mounted around the connecting portion  34  of the third connecting leg  3  such that solder can be applied thereto to electrically connect both together; the electromagnet  43  faces, and is relatively close to, the attracted portion  32  of the third connecting leg  3 . In addition, the circuit board  4  is provided with a timing device (not shown) such that it will be automatically disconnected from the power supply at a preselected time after it has been energized. 
     The control button  18  has the same size and specification as ordinary switches, and has a power-on end  181 , a power-off end  182  on the outer side, and a first, and a second pushing protrusions  184 , and  185  on the inner side, and has a transparent cover  183  mounted on a through hole formed thereon. The control button  18  is pivoted to a middle part of the front part  19  of the housing member  1  from a middle part thereof with the first, and the second pushing protrusions  184 , and  185  passing through the upper, and the lower through holes of the front part  19  respectively to face the contacting portions  33 , and the attracted portion  32  of the third connecting leg  3 . 
     Referring to FIG. 5, in using the timed switch after the same has been fitted to an appliance with the first and the second connecting legs  2  and  41  being electrically connected to the wires from the power supply, and the third connecting leg  3  to the input terminal of the appliance, the power-on end  181  of the control button  18  is pushed towards the front part  19  such that the second pushing protrusion  185  makes the attracted portion  32  of the third leg  3  move towards, and get into contact with, the electromagnet  43 , and makes the upper end contacting portion  33  move towards, and get into contact with, the contacting portion  21  of the first connecting leg  2 , thus completing the circuit of the circuit board  4  in other words, now electricity can travel through the circuit board  4  from the first and the second connecting legs  2  and  41  because the connecting portion  34  is already electrically connected to the circuit board  4 . And, the electromagnet  43  is now energized to attract the attracted portion  32  of the third leg  3  so as to make the upper end contacting portion  33  of the third leg  3  continue to contact the contacting portion  21  of the first leg  2 . Thus, electricity can travel through the third leg  3  to energize the appliance. The indicating light  44  also emit light through the transparent cover  183  as a sign. In addition, the timing device on the circuit boards  4  is also activated when the circuit board  4  is completed; thus, the flow of the electricity on the circuit board  4  can be automatically cut after preselected time for the timing device, and the electromagnet  43  can no longer attract the attracted portion  32 , allowing the upper end contacting portion  33  of the flexible vertical part to be biased away from the contacting portion  21  of the first leg  2  by the resilient strip portions  31 . Therefore, the appliance can be automatically turned off after it has been energized for the preselected time. 
     To turn off the appliance with the timed switch manually before it is automatically turned off at the preselected time, the power-off end  182  of the control button  18  is pushed so that the first pushing protrusion  184  makes the upper end contacting portion  33  of the third leg  3  separate from the contacting portion  21 . Thus, the circuit of the circuit board  4  becomes open, and the electromagnet  43  can no longer attract the attracted portion  32 , i.e. the attracted portion  32  no longer contacts the electromagnet  43  and the contacting portion  33  no longer contacts the contacting portion  21 . 
     From of the above description, it can be easily understood that the time switch of the present invention has desirable features as follows: 
     1. The timed switched can be easily used by means of pushing the power-on end, and the power-off end of the control button to energize the appliance and at the same time actuate the timing device for automatically cutting same off at the preselected time, and to manually turn off the appliance respectively. 
     2. The timed switch can be fitted to appliances that are already equipped with protective switches such as temperature switches so as to provide the appliances with double protection. 
     3. The control button of the timed switch has the same size, and specification as ordinary switch; therefore it can be easily fitted to all sorts of appliances.