Patent Publication Number: US-2005115927-A1

Title: Vacuum switch

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an electric power vacuum switch such as circuit breaker or conductor and, more particularly, relates to a radiating structure of a terminal conductor of the vacuum switch.  
      2. Description of the Related Art  
      Generally in a conventional vacuum switch, a fin-shaped radiator including a protrusion on an outer periphery is mounted on a terminal conductor thereof, thereby making a radiating area larger and suppressing a heat generation at the time of being conducted. Such an invention is proposed, for example, in the Japanese Patent Publication (unexamined) No. 40019/1999.  
      In the conventional vacuum switch, since a fin shape of a radiator forms protrusion outwardly, the protrusion, being a live part at a high voltage, is in the sate likely to discharge due to electrostatic focusing action. Normally, a vacuum switch is used in an electric power circuit of AC three-phase type, and three-phases of terminal conductors and radiators having an analogous configuration are located in the proximity. In order for the protrusion of a radiator to possess a predetermined satisfactory insulating performance between the phases, as well as between the phases and an earth electric potential, air clearance for the purpose of insulation becomes larger between one radiator and another, as well as between the radiators and a peripheral housing. As a result, a problem exists in that a vacuum switch comes to be larger.  
     SUMMARY OF THE INVENTION  
      The present invention was made to solve the above-discussed problem, and has an object of obtaining a vacuum switch in which an electrostatic focusing occurs relatively less at a radiator mounted on a terminal conductor thereby enabling to make smaller an air clearance between the radiator and a peripheral member.  
      A vacuum switch according to the invention is provided with a vacuum valve including a stationary-side terminal conductor and a moving-side terminal conductor, and the vacuum switch is further provided with a radiator that is fixed to the mentioned terminal conductor and includes a cover surrounding an outer periphery of a fin-shaped protrusion extending outwardly from the mentioned terminal conductor.  
      In the vacuum switch of the invention, it is possible to make smaller an air clearance between the radiator and a peripheral member thereby downsizing the vacuum switch.  
      Further, in the vacuum switch according to the invention, the plurality of fins provided with a cover making open the side face of the fins and surrounding the outer periphery thereof are integrally molded on the mentioned terminal conductor.  
      In the vacuum switch of the invention, since the fins provided with a cover are integrally molded on the terminal conductor, it is possible to reduce number of parts, make assembling easier, and improve effect of radiation.  
      The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a top view showing a vacuum switch according to a first preferred embodiment of the present invention.  
       FIG. 2  is a cross sectional view taken along the line A-A of  FIG. 1 .  
       FIG. 3  is a perspective view of a radiator for use in the vacuum switch in  FIG. 1 .  
       FIG. 4  is a cross sectional view taken along the line B-B of  FIG. 3 .  
       FIG. 5  is a perspective view showing a terminal conductor for use in a second embodiment.  
       FIG. 6  is a top view showing a vacuum switch according to the second embodiment on which the stationary-side terminal conductor is mounted.  
       FIG. 7  is a perspective view showing a terminal conductor for use in a third embodiment.  
       FIG. 8  is a top view showing a vacuum switch according to a fourth embodiment.  
       FIG. 9  is a perspective view of a radiator for use in the fourth embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     Embodiment 1  
       FIG. 1  is a top view showing a vacuum switch according to a first preferred embodiment of the invention,  FIG. 2  is a cross sectional view taken along the line A-A of  FIG. 1 ,  FIG. 3  is a perspective view of a radiator for use in  FIG. 1 , and  FIG. 4  is a cross sectional view taken along the line B-B of  FIG. 3 . It is to be noted that, in a three-phase vacuum switch, three pieces of one-phase vacuum switches having an analogous configuration are located in the proximity. The reference numerals are indicated with a, b, c in the drawings is to make a distinction between the phases. Referring to the drawings, a vacuum valve  1  forming a contact is housed in an insulating frame  2 . A stationary-side terminal conductor  3  of the vacuum valve  1  extends between a front mounting part  4  and a rear mounting part  5  of the insulating frame  2 , and fixedly mounted onto each mounting part  4 ,  5 . The stationary-side terminal conductor  3  consists of a T-shaped portion  6  of substantially T shape in cross section and which extends between the front mounting part  4  and the rear mounting part  5 , and a vertical strip portion  7  leading outwardly from the insulating frame  2 . An end face of a stationary electrode plate  8  of the vacuum valve  1  is in contact with a lower surface of the T-shaped portion  6 , and both faces are fixed to each other. A main circuit junction of the stationary-side terminal conductor  3  is provided at an end of the strip portion leading outwardly.  
      A moving-side terminal conductor  16  of the vacuum valve  1  includes a strip portion  18  one end of which is fixedly mounted onto a front mounting part  17  of the insulating frame  2 . A main circuit junction  19  of the moving-side terminal conductor  16  is provided at the other end of the strip portion  18 . A moving-side terminal fitting  20  is fixed to a moving portion of the vacuum valve  1  and forms a part of the moving-side terminal conductor  16 . A flexible conductor  21  is connected to the moving-side terminal fitting  20  at one end, and is connected to the strip portion  18  at the other end. An insulating rod  22  is connected to a moving portion of the vacuum valve  1  at one end, and is connected to an operating mechanism (not shown) of this vacuum valve  1  at the other end.  
      At the strip portion  7  of the stationary-side terminal conductor  3 , a radiator-mounting base  26  is integrally formed on both sides of the strip portion  7 , and a stationary-side radiator  27  is bonded or secured with a bolt to each base  26 . At a vertical part of the T-shaped portion  6  of the stationary-side terminal conductor  3 , a radiator-mounting base  28  is integrally formed on both sides of the vertical part. Further, a stationary-side radiator  29  as shown in  FIGS. 3 and 4  is bonded or secured with a bolt to each base  28 . Like manner, at the strip portion  18  of the moving-side terminal conductor  16 , a radiator-mounting base (not shown) is integrally formed on both sides of the strip portion  18 , and a moving-side radiator  30  is bonded or secured with a bolt to each base. A moving-side radiator  32  is fixed to the moving-side terminal fitting  20  via the mentioned radiator-mounting base  31 .  
      Each radiator  27 ,  29 ,  30 ,  32  is provided with a plurality of fin-shaped protrusions  36  (see  FIGS. 3 and 4 ) extending outwardly from the stationary-side terminal conductor  3  or the moving-side terminal conductor  16  respectively secured via a mounting base. Further, a cover  37  surrounding the protrusion  36  is provided on an outer periphery of the protrusion  36 . Each radiator  27 ,  29 ,  30 ,  32  is molded of copper, aluminum or the like of a high thermal conductivity along with the fin-shaped protrusion  36  and the cover  37 . As shown with  FIGS. 3 and 4 , in each radiator  27 ,  29 ,  30 ,  32 , a cover  37  surrounding a plurality of fin-shaped protrusions  36  is provided on the outer periphery of the protrusions  36 . However, side faces of each radiator  27 ,  29 ,  30 ,  32  are open to efficiently perform radiation of heat. In the vacuum switch of such a constitution, since the cover  37  is applied to ends of the fin-shaped protrusion  36  of the radiator  27 ,  29 ,  30 ,  32  and side faces of the fin-shaped protrusion  36  are open, not only radiation of heat is efficiently performed, but the electrostatic focusing is relieved thereby making discharge less likely to occur. Consequently, it is possible to make smaller an air clearance between the three-phases of radiators, and between the radiator and the peripheral housing thereby enabling to downsize a vacuum switch.  
     Embodiment 2  
       FIG. 5  is a perspective view showing a terminal conductor for use in a second embodiment of the invention. In the case of the foregoing first embodiment, the radiator  27  is fixed to the vertically located strip portion  7  of the stationary-side terminal conductor  3 , whereas in this second embodiment, a horizontally located strip portion  41  is used instead of the vertically located strip portion  7 . As shown in  FIG. 5 , by integrally molding a plurality of fins  43 , of which side face is open and which includes a cover  42  surrounding the outer periphery, on an outer periphery of the horizontally located strip portion  41  of the stationary-side terminal conductor  3 , number of parts is reduced and assembling becomes easy.  FIG. 6  is a top view of a vacuum switch on which the stationary-side terminal conductor according to this second embodiment is mounted. Since a heat resistance between the strip portion  41  of the stationary-side terminal conductor  3  and the fin  43  is reduced, the effect of radiation of heat is improved. Furthermore, application of such construction is not restricted to the stationary-side terminal conductor  3 , and the moving-side terminal conductor  16  may also be preferably constructed likewise.  
      In the drawings, like reference numerals indicate the same or like parts.  
     Embodiment 3  
       FIG. 7  is a perspective view showing a terminal conductor for use in a third embodiment of the invention. As shown in  FIG. 7 , by integrally molding a fin  48  of which side face is open and which includes a cover  47  surrounding an outer periphery in an internal part of a horizontally located strip portion  46  of the stationary-side terminal conductor  3 , the same effect as the second embodiment can be assured. Since a conductive current-carrying part having a large cross section is located at an outer peripheral portion, the terminal conductor possesses a skin effect that an AC current is likely to flow through a surface portion of the conductor. Further, such a terminal conductor allows lower decrease in high flexure rigidity as compared with flexure rigidity of a conductor having the same outside dimension without the fin  48 . Furthermore, in the terminal conductor according to this third embodiment, it is unnecessary to make an outer dimension of a conductor rather large as compared with a terminal conductor without the fin  48 , and as a result it is possible to make the stationary-side terminal conductor  46  lighter. In addition, application of such construction is not restricted to the stationary-side terminal conductor  3 , and the moving-side terminal conductor  16  may also be constructed likewise.  
     Embodiment 4  
       FIG. 8  is a top view showing a vacuum switch according to a fourth embodiment.  FIG. 9  is a perspective view of a radiator for use in this fourth embodiment. As a part of a stationary-side terminal conductor  3  according to this fourth embodiment, instead of the T-shaped portion  6  according to the foregoing first embodiment, a horizontal located strip portion  51  is employed. On a top surface of this strip portion  51 , an annular radiator  52  is secured with a bolt or adhesive. In the annular radiator  52 , a plurality of fin-shaped protrusions  54  are radially provided from a central part  53 , and there is provided an annular cover  55  making a side face of the fin-shaped protrusions open and surrounding an outer periphery. The annular radiator  52  is formed of copper, aluminum or the like of a high thermal conductivity. In the vacuum switch of such a constitution, since ends of the fin-shaped protrusion  54  of the annular radiator  52  is applied with the cover  55  and side faces of the fin-shaped protrusion  54  are open, satisfactory radiation of heat is achieved and the electrostatic focusing is relieved, thereby making the discharge less likely to occur. Consequently, it is possible to make smaller an air clearance between the three-phases of radiators and between the radiator and the peripheral housing, thereby enabling to downsize a vacuum switch.  
      While the presently preferred embodiments of the present invention have been shown and described. It is to be understood that these disclosures are for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.