Patent Publication Number: US-6713697-B2

Title: Dust and moisture free switch

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dust and moisture free switch and, particularly, to a switch, which has an isolation part disposed between a control plate and a casing to prevent the dust or the moisture from disturbing the contact pole device at the bottom of the casing. 
     2. Description of Related Art 
     It is known that the switch has been used for years in the field of power supply as a required device for controlling the power on or off and avoiding accidents caused by continuing supplying the power. The switch usually can be classified into a constant on switch, which is off at the time of the current being not taken, and a constant off switch, which is on at the time of the current being taken. Thus, products powered by the electricity have provided with a switch and the basic principle for operating a switch is in that two electric poles are utilized to connect with each other as a close circuit for constituting a state of current taking and the two electric poles disconnect from each other as an open circuit to form a state of current not taking. 
     Generally, safety is also an important factor has to be considered in addition to an accurate operation of power on or power off. For instance, the switch has to be not leakage of electricity and not incorrect connection. Besides, the switch has to be free from dust or moisture in special locations such as a working environment with floating powder dust or heavy moisture such that it can prevent the contact pole device in the switch from short circuit or corrosion and prolong the life span of the switch. Currently, a treatment with regard to anti-dust or anti-moisture is done with a soft cover being attached to the top of the switch and a projecting rectangular frame enclosing the control plate thereof so as to conceal the switch at the top thereof. However, the efficiency of the wrap up type switch is in that both arc ends of the control plate just corresponds to both end edges of the rectangular frame so that it has to overcome a resistance force at each end edge due to the rectangular frame having a height during an operation of pressing and it is hard to operate smoothly. Besides, the wrap up type switch at the rectangular frame thereof is easy to result in breaking because of being repeatedly pressed and lose the function of ant-dust or anti-moisture. 
     SUMMARY OF THE INVENTION 
     The crux of the present invention is to provide a dust and moisture free switch, which includes a hollow casing, a contact pole device, a control plate and an isolation part. The contact pole device is inserted to the bottom of the casing with a stationary pole and a support pole being inserted into and locating at a respective pole hole and an arc pole being attached to the top of the support pole such that the arc pole can swing leftward and rightward. The control plate is joined to the upper portion of the casing and has the bottom thereof being arranged with a central hollow post to fit with an extensible stir lever, which has a bottom thereof contacting with the arc pole. The isolation part is made of soft high molecular plastic material and passed through by and fitting with the stir lever so as to be located at and closely joined to the inner wall of the casing to perform a function of blocking dust or moisture to enter the bottom of the casing. The stir lever can slide on the arc pole in case of an end of the control plate being pressed such that the arc pole can touch or detach from the stationary pole selectively to perform power on or off. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can be more fully understood by reference to the following description and accompanying drawings, in which: 
     FIG. 1 is an exploded perspective view of a dust or moisture free switch according to the present invention; 
     FIG. 2 is a sectional view of the switch according to the present invention illustrating the switch being in a state of off; and 
     FIG. 3 is a sectional view similar to FIG. 2 illustrating the switch being in a state of on. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, basically, a dust or moisture free switch according to the present invention includes a casing  1 , a contact pole device  2 , a control plate  3  and an isolation part  4 . 
     Wherein, the casing  1  is a hollow base with two pole holes  11 ,  12  at the bottom thereof for being inserted and locating the contact pole device  2 . The casing  1  at the top thereof extends a casing frame  13  as a stopper while the contact pole device  2  is inserted into preset holes of an electric appliance. In order to be capable of joining and locating the control plate  3  easily, the casing  1  at the front and the rear sides thereof has an axial hole  14  respectively to be disposed oppositely and at the left and right sides thereof has a bow-shaped elastic lock  15  respectively to be disposed oppositely. The elastic lock  15  at the upper bent half thereof is a transverse track section  151  and at the lower bent half thereof is a flat section  152  such that the flat section  152  provides a guide function and the transverse track section  151  can perform an engaging function with the respective rim of the preset holes in the electric appliance as soon as the elastic lock  15  is inserted into the preset holes. The casing  1  at the inner wall surface  16  thereof has a middle spacing wall  17  so that a wall gap  171  can be formed between the inner wall surface  16  and the middle spacing wall  17  for locating the isolation part  4 . Thus, a plurality of vertical locating ribs  172  are arranged between the inner wall surface  16  and the spacing wall  17 . 
     The contact pole device  2  is prior art and has a stationary pole  21  inserted in the pole hole  11  and a support pole  22  inserted in another pole  12 . Further, an arc pole  23  is crossly inserted in the recess opening  221  of the support pole  22  such that two opposite engaging recesses  231  at the middle of the arc pole  23  engage with the recess opening  221 . Hence, the arc pole  23  can perform a leverage movement on the support pole  22  so that a movable joint  232  of the arc pole  23  can selectively touch or detach from a fixed joint  211  at the top of the stationary pole  21  to perform power on or off. 
     The control plate  3  at the top thereof has a curve plane between two lateral sides  31  thereof and provides with two opposite juts  32  corresponding to the two axial holes  14  and the control plate  3  can swing leftward and rightward with respect to the casing  1  to facilitate pressing once the juts  32  engage with the axial holes  14 . The control plate  3  at the bottom thereof has a central hollow post  33  for receiving and locating an extensible stir lever  34  and, for instance, a spring  35  can be disposed between the hollow post  33  and the stir lever  34  to allow the stir lever  34  contacting with the arc pole  23  constantly such that the stir lever  34  moves with the control plate  3  to actuate the arc pole  23  for controlling the power on/off. Besides, the hollow post  33  has a lever ring  36  additionally with a ring clearance  361  in between. 
     The isolation part  4  is a plate made of high molecular plastic material such as PVC and at the center thereof protrudes a fitting ring  41  corresponding to the ring clearance  361  such that the fitting ring  41  can be inserted into the ring clearance  361 . The stir lever  34  is arranged to pass through a ring hole  411  of the fitting ring  41  and the periphery of the isolation part  4  has a joining edge  42  and engaging recesses  43  corresponding to the clearance  171  and locating ribs  172  respectively for being able to engage with each other so that the upper side of the contact pole device  2  can be covered in the casing  1  to prevent the dirt and the moisture from entering the bottom of the casing  1 . Therefore, it is possible to obtain a dust and moisture free effect. 
     Referring to FIGS. 2 and 3, while the switch of the present invention is in use, the only thing has to be done is to press the control plate  3  and then the contact pole device  2  can move relatively in the casing  1  to actuate the power on or off. The isolation part  4  is located between the control plate  3  and the casing  1  to keep the dirt and the moisture out of the bottom of the casing so as not to influence the normal function of the contact pole device  2 . 
     It is appreciated that the isolation part in the switch of the present invention is fixedly disposed between the control plate and the casing so that the control plate can be free from being disturbed during the operation of pressing. Further, the fitting ring of the isolation part can be actuated synchronously with the stir lever to avoid break resulting from repeated operations so that it is possible to extend the life span of the switch. 
     While the invention has been described with reference to the a preferred embodiment thereof, it is to be understood that modifications or variations may be easily made without departing from the spirit of this invention, which is defined by the appended claims.