Abstract:
A rolling press member for power switch includes a metal roller capable of free rolling movements and disposed at an end portion of the press member, with the roller pressing against an internal contact plate. When turning on and off the switch, the roller displaces at the contact plate using rolling movements thereof, thereby enabling smoother operations of the power switch.

Description:
BACKGROUND OF THE INVENTION 
   (a) Field of the Invention 
   The invention relates to a rolling press member for power switch, and more particularly, to a rolling press member having a roller at an end portion of the press member placed in a center column of a button, thereby elevating displacement smoothness of a contact plate at an interior of a switch housing. 
   (b) Description of the Prior Art 
   Switches are generally provided for various kinds of electric appliances or mechanical apparatus as controlling means for shutting down or conducting power supplies. To be more precise, these switches are utilized for facilitating turning on or off power supplies of these equipments. Referring to  FIG. 7  showing a conventional fundamental structure of a common switch, a switch housing A is pivotally disposed with a button B at an upper portion thereof. The button B has a center column B 1  at a bottom center thereof. An interior of the center column B 1  is provided with an elastic member B 2  for pushing against an elastic press member B 3 , which is pressed against and joined with an arched contact plate C at a bottom portion of the switch housing A. The contact plate C has symmetrical apertures C 1  at edges of a middle section thereof, and is erected at a live wire conducting strap D disposed at the bottom portion of the switch housing A via the apertures C 1 . The contact plate C further has a contact point C 2  at one end thereof, and the contact point C 2  is in contact with another live wire conducting strap E when being moved downward. As shown in the diagram, in occurrence that the button B is provided with an additional power indication lamp F, the elastic member B 2  has two ends thereof in contact with the power indication lamp F and the arch contact plate C along with the press member B 3  to form a live wire route. The button B is also provided with an elastic member G connected with the power indication lamp F. The elastic member G is in contact with an earth wire conducting strap H to serve as an earth route of the power indication lamp F. Using the aforesaid structure, pressing of the button B impels swaying of the center column B 1  to change a contact status of the contact point C 2  of the contact plate C relative to the live wire conducting strap E using the elastic and contractible press member B 3 , so as to appropriately control conducting or shutting off of the switch. In addition, under a conducted status, the power indication lamp F in the button B is lit up. 
   However, after thorough study, it is observed that elastic contraction of the press member B 3  relative to the contact plate C is performed from swaying of the center column B 1  from pressing the button B. Wherein, before being impelled, a status of the hollow press member B 3  being contact with the contact plate C is regarded as a “direct contact”, meaning that a resistance against sliding movements is comparatively larger with more likely wear from abrasion. Meanwhile, in order to maintain the press member B 3  remaining in contact with the elastic member B 2  when being pushed downward, it is essential that contraction displacements of the press member B 3  relative within the center column B 1  be quite smooth in all time, and thus the press member B 3  is applied with grease I. Nevertheless, as shown in the diagram, the grease I is often accumulated between a lower end of the center column B 1  and the outer surfaces of the press member B 3 , and therefore reliable lubricating effects between an inner wall of the center column B 1  and the press member B 3  can hardly be accounted. Above all, when such type of switch is electrically conducted, temperatures of the press member B 3  and the contact plate C are elevated. The elevated temperatures melt and drain away the grease I accumulated between the lower end of the center column B 1  and the outer surfaces of the press member B 3 , and thus lubricating effects are made even more unsatisfactory. Similarly, referring to  FIG. 8 , another type of press member B 4  having a solid column also has the aforesaid drawback. 
   Referring to  FIG. 9 , the aforesaid press member B 3  for switching is replaced by a ball bearing B 5  made of metal materials. However, to assemble the ball bearing B 5 , grease is necessarily applied to outer surfaces of the elastic member B 2  after placing the elastic member B 2  into the center column B 1 , so as to temporarily adhere to the ball bearing B 5 . After placing the contact plate C into the switch housing A, the button B together with the elastic member B 2  and the ball bearing B 5  are placed into the switch housing A. During the assembly process, the ball bearing B 5  not only is prone to fall off due to any slight contact, but may also be easily bounced away when sliding the ball bearing B 5  into the center column B 1  by pressing the elastic member B 2 . Therefore, assembly process of this structure is quite complicated while being time consuming. 
   SUMMARY OF THE INVENTION 
   The object of the invention is to provide a rolling press member for power switch having an inlayed roller at an end portion of the press member. Using the roller, displacements of a contact plate an interior of a switch housing are made smoother. The invention is characterized that, a metal roller capable of free rolling movements is disposed at an end portion of the press member, with the roller pressing against the internal contact plate. When turning on and off the switch, the roller displaces at the contact plate using rolling movements thereof, thereby enabling smoother operations of the power switch. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a structural schematic view of a first embodiment according to the invention. 
       FIG. 2  shows a sectional view of a first embodiment according to the invention. 
       FIG. 3  shows a schematic view showing motions of a first embodiment according to the invention. 
       FIG. 4  shows a sectional view of a second embodiment according to the invention. 
       FIG. 5  shows a sectional view of a third embodiment according to the invention. 
       FIG. 6  shows a sectional view of a fourth embodiment according to the invention. 
       FIG. 7  shows a conventional sectional view of a first prior art. 
       FIG. 8  shows a conventional sectional view of a second prior art. 
       FIG. 9  shows a conventional sectional view of third prior art. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   To better understand the invention, detailed descriptions shall be given with the accompanying drawings below. 
   Referring to  FIGS. 1 and 2 , a fundamental structure of a switch in a first embodiment according to the invention comprises: 
   a switch housing  1 ; 
   a button  2  pivotally disposed at the switch housing  1 ; and having a center column  21  formed at a bottom center thereof, and an elastic member  22  disposed at an interior thereof and for pressing against a press member  23  for forming an elastically contractible end; 
   an arched contact plate  3  being in contact at a bottom portion; and 
   having symmetrical apertures  31  at edges of a middle section thereof that are connected to a conducting strap  4 , so as to erect the contact plate  3  at a bottom portion of the switch housing  1 , and a contact point  32  at one end thereof, wherein the contact point  32  is in communication with another live wire conducting strap  5  when moving in a downward direction; and 
   an elastic member  6  having one end thereof pushed against a bottom portion of the button  2  to connect with a power indication lamp  7  in the button  2 , and the other end pressed against an earth wire conducting strap  8 . 
   Using a hollow tube structure, the press member  23  forms a contracted segment  231  at an outer end of the contact plate  3 . An interior of the press member  23  is placed with a roller  24  made of a metal material, such that the roller  24  is partially extended out of the contracted segment  231  without being entirely bounced out to an exterior while being capable of free rolling movements. Furthermore, the elastic member  23  is pushed against the roller  24  to further displace the press member  23 , thereby having the partially extended roller  24  at an end portion of the press member  23  come into contact with the contact plate  3 . To lubricate the roller  24 , grease is injected into the hollow press member  23 . 
   Referring to  FIG. 3 , according to the aforesaid structure, when pressing the button  2  to impel swaying of the center column  21 , the extended roller  24  at the end portion of the press member  23  at an interior thereof rolls against the contact plate  3 , and the press member  23  forms an elastic contraction mode with the roller  24  due to movements of the elastic member  22  being pressed. Wherein, the roller  24  rolls against the contact plate  3 , and a resistance of the rolling movements is rather insignificant for avoiding rapid wear from abrasion. Moreover, according to the aforesaid design, the roller  24  is first disposed in the press member  23  and then placed into the elastic member  22 . An assembled structure is installed in the center column  21  followed by fastening of the button  2  in the switch housing  1 , and therefore assembly process of the entire structure is made convenient without causing concerns of elements being bounced out. 
   Apart from the first embodiment, the following designs provide other embodiments in conjunction with the novel characteristics of the roller  24 .
     1. Referring to  FIG. 4  showing a second embodiment, without being capable of displacements, the roller  24  is located in a fixed position to perform rolling movements relative to the press member  23 . A shrunk stop ring  232  is formed at an upper portion of the contracted segment  231  at a front end of the press member  23  and corresponding to an upper side of the roller  24 . The roller  24  is retained between an opening of the contracted segment  231  and the ring  232 , so as to perform rolling movements in a located region thereof. At the same time, the elastic member  22  has one end thereof pressed against the ring  232  instead of being directly pressed against the roller  24 , thereby offering the roller  24  with even more smooth rolling movements relative to the contact plate  3 .   2. Referring to  FIG. 5  showing a third embodiment, a press member  25  having a solid column is adopted. The press member  25  has a roller recess  251  at one end thereof for accommodating the roller  24 . This design locates the roller  24  relative to the press member  24  for rolling movements without allowing the roller  24  with displacements.   3. Referring to  FIG. 6  showing a fourth embodiment derived from the third embodiment, to enhance lubricating effects, the solid press member  25  is further provided with a lubrication channel  252  that is in communication with the roller recess  251 , so as to lubricate the roller  25  with injected grease.   

   Moreover, in the aforesaid embodiments, the button  2  is provided with a power indication lamp  7  at an interior thereof. However, the press members  23  and  25  having the roller  24  may also applied in common power switches without the power indication lamp  7 , so as to eliminate components of the elastic member  6  and the earth wire conducting strap  8 . 
   Conclusive from the above, according to the rolling press member for power switch, a metal roller is disposed at an end portion of the press member in a hollow or a solid form, and is for coming into contact with a contact plate at an interior of a switching housing using rolling movements thereof. The design not only offers smoother switching of a button, but also minimizes abrasion and wear of internal parts as well as facilitating assembly of all the parts. 
   It is of course to be understood that the embodiments described herein are merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.