Patent Document

BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the internal mechanism of a motor and more particularly, to a carbon brush holder for motor. 
   2. Description of the Related Art 
   Taiwan utility model no. 290200 discloses a carbon brush holder, which comprises a copper conducting receptacle and a holder base. The copper conducting receptacle is made from a copper sheet material by stamping, having an upwardly protruded lead wire connection strip. The holder base has a vertical receiving hole. The copper conducting receptacle is fastened to the receiving hole of the holder base, keeping the lead wire connection strip extended to the outside of the holder base. Because the copper conducting receptacle is made from a copper sheet material by stamping, the wall thickness of the copper conducting receptacle is limited. Therefore, this design of carbon brush holder is not suitable for large current application. 
   Taiwan utility model no. 292024 discloses another structure of carbon brush holder. According to this design, the carbon brush holder comprises a copper conducting receptacle and a holder base holding the copper conducting receptacle. The copper conducting receptacle is made from a copper sheet material by stamping, having a lead wire connection upwardly protruded from the top side and a locating portion protruded from the outside4 wall. The holder base has a stop portion for stopping against the locating portion of the copper conducting receptacle after insertion of the copper conducting receptacle into the holder base. Similar to the aforesaid prior art design, this structure of carbon brush holder is not suitable for large current application. 
     FIGS. 11 and 12  show a conventional carbon brush holder  1  that fits for large current application. The carbon brush holder  1  comprises a copper conducting receptacle  2 , which is extruded from copper and has a tubular configuration, a lead wire terminal  3  which is fastened to the top side of the outside wall of the copper conducting receptacle  2  with a rivet  4  and has a rectangular configuration, and an electrically insulative holder base  5 , which comprises a upwardly extended vertical receiving hole  6  fitting the copper conducting receptacle  2 . The wall thickness of the copper conducting receptacle  2  is determined subject to the required large current load. During actual practice, the upper part of the lead wire terminal  3  protruding over the top side of the copper conducting receptacle  2  is bent outwards for the connection of a lead wire. However, because the lead wire terminal  3  is fastened to the copper conducting receptacle  2  with a rivet  4 , bending the upper part of the lead wire terminal  3  outwards causes loosening of the lead wire terminal  3  (see FIG.  12 ). Loosening of the lead wire terminal  3  may result in a short circuit. 
   SUMMARY OF THE INVENTION 
   The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a carbon brush holder, which keeps the lead wire terminal positively positioned in position against biasing force. 
   To achieve this and other objects of the present invention, the carbon brush holder comprises an electrically insulative holder base, the electrically insulative holder base comprising an upwardly extended vertical receiving hole; a copper conducting receptacle tightly press-fitted into the vertical receiving hole of the electrically insulative holder base, the copper conducting receptacle having a tubular configuration; and a lead wire terminal riveted to an outside wall of an upper part of the copper conducting receptacle; wherein the electrically insulative holder base comprises an inside locating groove upwardly extended to a top side thereof for the positioning of the lead wire terminal upon insertion of the copper conducting receptacle into the vertical receiving hole of the electrically insulative holder base. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded view of a carbon brush holder according to a first embodiment of the present invention. 
       FIG. 2  is a plain assembly view of the carbon brush holder according to the first embodiment of the present invention. 
       FIG. 3  is a sectional view taken along line  3 — 3  of FIG.  2 . 
       FIG. 4  is a plain assembly view of a carbon brush holder according to a second embodiment of the present invention. 
       FIG. 5  is a plain assembly view of a carbon brush holder according to a third embodiment of the present invention. 
       FIG. 6  is a plain assembly view of a carbon brush holder according to a fourth embodiment of the present invention. 
       FIG. 7  is a plain assembly view of a carbon brush holder according to a fifth embodiment of the present invention. 
       FIG. 8  is a perspective assembly view of a carbon brush holder according to a sixth embodiment of the present invention. 
       FIG. 9  is a perspective assembly view of a carbon brush holder according to a seventh embodiment of the present invention. 
       FIG. 10  is a plain assembly view of a carbon brush holder according to an eighth embodiment of the present invention. 
       FIG. 11  is an exploded view of a carbon brush holder according to the prior art. 
       FIG. 12  is a plain assembly view of the prior art carbon brush holder shown in FIG.  11 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a carbon brush holder  10  in accordance with the first embodiment of the present invention is shown comprising a copper conducting receptacle  20 , which is extruded from copper and has a tubular configuration, a lead wire terminal  30 , which is fastened to the top side of the outside wall of the copper conducting receptacle  20  with a rivet  31  and has a rectangular configuration, and an electrically insulative holder base  40  injection-molded from plastics, which comprises a upwardly extended vertical receiving hole  41  fitting the copper conducting receptacle  20 , and a rectangular locating groove  42  formed inside the receiving hole  41  and extended to the top. 
   The copper conducting receptacle  20  is press-fitted into the receiving hole  41  of the electrically insulative holder base  40 , keeping the lower part of the lead wire terminal  30  engaged in the locating groove  42  and the upper part of the lead wire terminal  30  protruding over the topmost edge of the electrically insulative holder base  40 . 
   As indicated above, the locating groove  42  holds the lead wire terminal  30  firmly in place, preventing loosening of the lead wire terminal  30  from the copper conducting receptacle  20  upon stretching of the lead wire, which is connected to the lead wire terminal  30 . Therefore, the invention prevents electric shock due to loosening of the lead wire terminal  30 . Further, because the electrically insulative holder base  40  is injection-molded from plastics, it is easy to make a cavity in the mold for the locating groove  42 . Therefore, the manufacturing of the carbon brush holder  10  is simple, and its manufacturing cost is low. 
   The lead wire terminal and the locating groove may be made in a different form to have the lead wire terminals positively secured to the copper conducting receptacle  20 . 
   In the carbon brush holder, referenced by  50 , of the second embodiment of the present invention as shown in  FIG. 4 , the lead wire terminal, referenced by  51 , has a bottom positioning notch  52 , and the electrically insulative holder base, referenced by  56 , has an inside locating groove  53  at the top and an inside locating rod  54  suspended in the locating groove  53 . Upon insertion of the copper conducting receptacle, referenced by  55 , into the electrically insulative holder base  56 , the lead wire terminal  51  is plugged into the inside locating groove  53  to force the bottom positioning notch  52  into engagement with the inside locating rod  54 . 
   In the carbon brush holder, referenced by  60 , of the third embodiment of the present invention as shown in  FIG. 5 , the lead wire terminal, referenced by  61 , has a bottom protruding portion  62 , and the electrically insulative holder base of the carbon brush holder  60  has an inside locating groove  63  at the top and a recessed portion  64  in the locating groove  63  for receiving the bottom protruding portion  62  of the lead wire terminal  61  upon insertion of the bottom end of the lead wire terminal  61  into the inside locating groove  63 . 
   In the carbon brush holder, referenced by  70 , of the fourth embodiment of the present invention as shown in  FIG. 6 , the lead wire terminal, referenced by  71 , has a pointed bottom end  72 , and the electrically insulative holder base of the carbon brush holder  70  has an inside locating groove  73  with a bottom end  74  made gradually reduced toward the bottom side to fit the pointed bottom end  72  of the lead wire terminal  71 . 
   In the aforesaid embodiments, the bottom end of the lead wire terminal fits the configuration of the inside locating groove of the electrically insulative holder base so that the lead wire terminal can positively be positioned in the inside locating groove of the electrically insulative holder base. 
   In the carbon brush holder, referenced by  80 , of the fifth embodiment of the present invention as shown in  FIG. 7 , the electrically insulative holder base of the carbon brush holder  80  has an inside locating groove  81  and a raised portion  82  suspended in the inside locating groove  81 ; the lead wire terminal, referenced by  83 , has a guide groove  84  upwardly extended from the bottom end for receiving the raised portion  82  upon insertion of the lead wire terminal  83  into the inside locating groove  81 . 
   In the carbon brush holder, referenced by  90 , of the sixth embodiment of the present invention as shown in  FIG. 8 , the lead wire terminal, referenced by  91 , is fastened to the copper conducting receptacle  95  with a rivet  93 , having a narrow thin-wall portion  92  transversely disposed on the middle above the rivet  93 . Making a transverse groove  94  on the lead wire terminal  91  by stamping forms the thin-wall portion  92 . The thin-wall portion  92  stops or reduces transmission of biasing force to the rivet  93  when the lead wire terminal  91  is bent 
   In the carbon brush holder, referenced by  96 , of the seventh embodiment of the present invention as shown in  FIG. 9 , making a narrow transverse cut  99  on the lead wire terminal, referenced by  97 , forms a thin-wall portion  98  in the lead wire terminal  97 . The narrow transverse cut  99  can be made on either of the two opposite sides of the lead wire terminal  97 . 
   In the carbon brush holder, referenced by  100 , of the eighth embodiment of the present invention as shown in  FIG. 10 , the lead wire terminal, referenced by  101 , is fastened to the copper conducting receptacle, referenced by  103 , with a rivet  102 , having two bonding points  104  disposed at two opposite lateral sides above the rivet  102  and respectively welded to the copper conducting receptacle  103 . Because the lead wire terminal  101  is welded to the copper conducting receptacle  103  after having been riveted, the bonding strength between the lead wire terminal  101  and the copper conducting receptacle  103  is reinforced, and electric current can be transmitted to the copper conducting receptacle  103  through the lead wire terminal  101  stably. 
   Further, after the lead wire terminal has been riveted to the copper conducting receptacle and inserted with the copper conducting receptacle into the electrically insulative holder base, the distance between an outer side of said lead wire terminal and an inner side of said inside locating groove is smaller than 0.1 mm. 
   A prototype of carbon brush holder has been constructed with the features of FIGS.  1 ˜ 10 . The carbon brush holder functions smoothly to provide all of the features discussed earlier. 
   Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.

Technology Category: h