Patent Publication Number: US-2012045665-A1

Title: Battery pack

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/374,563, filed Aug. 17, 2010, entitled Battery Pack which is hereby incorporated in its entirety by reference herein. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The embodiment relates to a battery pack, in more detail, a battery pack having improved durability and safety. 
     2. Discussion of Related Art 
     In general, a battery pack composed of a plurality of battery cells connected in parallel and/or in series is used for devices, such as laptops and electric vehicles. The battery cells are connected by connection tabs with adjacent battery cells. Further, the battery cells are mounted in a case. 
     SUMMARY OF THE INVENTION 
     In one embodiment the invention provides a battery pack that can protect a plurality of battery cells against vibration, shock, and drop, by having fixing ribs that fix the battery cells in a holder case mounted on the battery cells. 
     The present invention, in one embodiment, also provides a battery pack that includes a means for fixing a lead wire to the holder case. 
     According to an aspect of the present invention, there is provided a battery pack that includes: a plurality of battery cells electrically connected by connection tabs; a holder case covering a portion of the outer surfaces of the battery cells; a protection circuit module mounted on the holder case; and a lead wire connecting the protection circuit module with the battery cells, in which the holder case has at least one fixing rib that fixes the battery cells and guides the lead wire. 
     The holder case, in one embodiment, includes a cover covering at least a portion of the battery cells, and a first extender and a second extender that extend from the cover, adjacent to both ends of the battery cells, in which the fixing ribs are disposed on the first extender and the second extender. 
     The battery cells, in one embodiment, are electrically connected by the connection tabs. 
     The fixing ribs, in one embodiment, are disposed outside the connection tabs, on the first extender and the second extender, to prevent the battery cells from moving. 
     The fixing rib, in one embodiment, is formed on the first extender and the fixing rib formed on the second extender are alternately disposed, in a zigzag shape when seeing the holder case from above. 
     The fixing rib, in one embodiment, is shaped to be divided left and right with a gap therebetween and the gap may be a lead wire-through hole. 
     Further, in one embodiment, a protrusion is formed outside the fixing rib to prevent the lead wire from protruding outside. 
     Further, in one embodiment, the first extender and the second extender may contact the upper portion and the lower portion of the battery cells and match with the outer circumference of the battery cells. 
     Further, in one embodiment, the lead wire is connected with the connection tab at one end and with the protection circuit module at the other end. 
     Further, in one embodiment, a guide groove that guides the lead wire passing through the lead wire-through hole may be further formed on the first extender and the second extender. 
     In this configuration, a protruding rib fixing the lead wire may be formed on the inner surface of the guide groove. In this configuration, the protruding rib may protrude in a constant thickness on both inner sides of the guide groove. Further, the protruding rib may protrude only at the inlet of the guide groove. 
     The holder case, in one embodiment, may be divided left and right and fastened to each other. 
     An external case, in one embodiment, may be provided on the holder case. 
     The external case, in one embodiment, may be composed of a first case and a second case, which are fastened to each other. 
     The inner surface, in one embodiment, of any one of the first case and the second case that contact an anti-interference portion of the holder case may be formed in order not to interfere with the guide groove. 
     According to the present invention, it is possible to better protect the battery cell from external vibration, shock, and drop by forming the fixing ribs in the holder case, such that it is possible to improve durability of the battery pack. 
     Further, it is possible to prevent or at least inhibit the lead wire from being cut by fixing the lead wire through the lead wire-through hole of the fixing rib, such that it is possible to improve safety of the battery pack. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention. 
         FIG. 1A  is a front perspective view showing when a holder case is mounted on a plurality of battery cells according to the present invention; 
         FIG. 1B  is a rear perspective view showing when the holder case is mounted on the battery cells according to the present invention; 
         FIG. 1C  is a view schematically showing when the holder case is mounted and fixed to the battery cells according to the present invention; 
         FIG. 2  is a perspective view of the holder case according to the present invention; 
         FIG. 3  is a perspective view enlarging the portion A of  FIG. 2 ; 
         FIG. 4A  is a perspective view enlarging the portion B of  FIG. 2 ; 
         FIG. 4B  is a perspective view showing a protruding rib different from that shown in  FIG. 4A ; 
         FIG. 5A  is a perspective view enlarging the portion C of  FIG. 2 ; 
         FIG. 5B  is a perspective view showing a guide member different from that shown in  FIG. 5A ; 
         FIG. 6  is a perspective view showing when an insulating sheet according to the present invention is attached; and 
         FIG. 7  is a perspective view showing a battery back equipped with an external case according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1A  is a front perspective view showing when a holder case is mounted on a plurality of battery cells according to the present invention and  FIG. 1B  is a rear perspective view showing when the holder case is mounted on the battery cells according to the present invention. 
     Referring to  FIGS. 1A and 1B , a battery pack according to one embodiment of the present invention includes a plurality of battery cells  10 , a holder case  20 , a protection circuit module  30 , a lead wire  50 , and fixing ribs  21 . 
     First, the battery cells  10  are chargeable/dischargeable cylindrical lithium ion batteries. The battery cells  10  according to an embodiment of the present invention are arranged in a five-series and two-parallel structure (5 S*2 P). That is, five sets of battery cell group which has a set of two battery cells connected in parallel are connected by connection tabs. The connection tabs  40  are conductive devices made, for example, of copper etc. and electrically connect the battery cell groups. 
     Hereinafter, connection relationship of the battery cell groups is described in more detail with reference to  FIG. 1A . Basically, two battery cells are connected in parallel. One end of each of the battery cells connected in parallel has a first pole and the other end has a second pole. The first poles of the battery cells are electrically connected to the protection circuit module by the connection tab  42  in  FIG. 1A . T he second poles of the battery cells are electrically connected with the first poles of the adjacent battery cells by the connection tab  40   d  in  FIG. 1B . The battery cells having the second poles at the other end are electrically connected with the first poles of the next battery cells by the connection tab  40   b . Therefore, total five groups of battery cells are connected in series and the second poles of the last battery cells are electrically connected with the protection circuit module  30  by the connection tab  42 . Meanwhile, it should be understood that the five-series and two-parallel structure (5 S*2 P) is exemplified, but the structure is not limited thereto and various connection structures may be used, if needed. 
     Meanwhile, the holder case  20  of the present invention may be formed to cover at least a portion of the battery cells  10 . In an embodiment of the present invention, the holder case  20  includes a cover  20   a  that covers the outer surfaces of the battery cells  10 , and a first extender  20   b  and a second extender  20   c  disposed close to both ends of the battery cells  10 , in the cover  20   a . The first and second extenders  20   b ,  20   c  may extend to the spaces defined between adjacent battery cell groups. That is, the ends of the first and second extenders  20   b ,  20   c  may be formed in a shape matching with the circumference of the cylindrical battery cells  10 , in which it is possible to prevent the battery cells from moving due to external shock. 
     Further, the first and second extenders  20   b ,  20   c  have at least one or more fixing ribs  21  at both ends of the battery cells  10  to maintain and fix the position of the battery cells  10 . Further, the fixing ribs  21  also have a function of guiding the lead wire  50  electrically connecting the battery cells  10  with the protection circuit module  30 . 
     The fixing ribs  21  are formed to contact the ends of the battery cells  10  and may be formed between the battery cells  10 . Referring to  FIG. 1A , the fixing rib  21  may be formed on the first extender  20   b  at the positions corresponding to the positions of the connection tabs  40   a ,  40   b . Referring to  FIG. 1B , the fixing rib  21  may be formed on the second extender  20   c  at the positions corresponding to the positions of the connection tabs  40   c ,  40   d . That is, the first extender  20   b  extending from the cover  20   ab  is positioned at the ends of the battery cells  10  and the second extender  20   c  is positioned at the other ends of the battery cells  10 , such that the fixing ribs are alternately formed at both ends of the battery cells  10 , thereby firmly fixing the battery cells  10  at their positions. 
     The positions where the fixing ribs  21  are formed may construct a zigzag shape, when seeing the holder case  20  from above.  FIG. 1C  is a plan view schematically showing the top of the holder case  20 , seen from above as described above. That is, as shown in  FIG. 1C , the fixing ribs  21  may be formed on the first extender  20   b  and the second extender  20   c  while being positioned on the first, second, third, and fourth connection tabs  40   a ,  40   b ,  40   c ,  40   d . Further, the battery cells ( 10  in  FIG. 1A ) fixed by welding with the first, second, third, and fourth connection tabs  40   a ,  40   b ,  40   c ,  40   d  are supported by the fixing ribs  21 . Therefore, the fixing ribs  21  disposed in a zigzag shape prevent or inhibit the battery cells ( 10  in  FIG. 1A ) from moving and also prevent the connection tabs  40  fixed to the battery cells from separating. That is, it is possible to improve durability of the battery pack against shock, drop, and vibration. Meanwhile, referring to  FIG. 1C , the battery cells are fixed in a zigzag shape in order not to be moved by the first, second, third, and fourth connection tabs  40   a ,  40   b ,  40   c ,  40   d  formed on the first extender  20   b  and the second extender  20   c . Further, the lead wire (not shown) passes through the first and second extenders  20   b ,  20   c  of the holder case, through the fixing rib  21  and a lead wire-through hole  23  formed in the fixing rib  21 . In this configuration, guide grooves  24  are formed on the first and second extenders  20   b ,  20   c  such that the lead wire  50  can be guided without protruding outside. This is described in detail below. 
       FIG. 2  is a perspective view of the holder case according to one embodiment of the present invention,  FIG. 3  is a perspective view enlarging the portion A of  FIG. 2 ,  FIG. 4A  is a perspective view enlarging the portion B of  FIG. 2 ,  FIG. 4B  is a perspective view showing a protruding rib different from that shown in  FIG. 4A ,  FIG. 5A  is a perspective view enlarging the portion C of  FIG. 2 , and  FIG. 5B  is a perspective view showing a guide member different from that shown in  FIG. 5A . 
     As shown in  FIGS. 2 to 3 , the fixing rib  21  is formed on the first extender  20   b  of the holder case ( 20 , see  FIG. 1 ) to support the connection tabs  40   a ,  40   b ,  40   c ,  40   d  positioned at the ends of the battery cells  10 . The fixing rib  21  may be divided left and right with a predetermined gap therebetween and the gap may be the lead wire-through hole  23  for guiding the lead wire  50 . Further, protrusions  22  may be formed to protrude from both sides facing the lead wire-through hole of the fixing rib  21 . The protrusions  22  function as locking member that prevent the lead wire passing through the lead wire-through hole  23  from being pulled out. 
     Further, the fixing rib  21  may be formed with the smallest area contacting the lead wire  50 . That is, it is possible to minimize or at least reduce the contact area between the lead wire  50  and the fixing rib  21  by making the middle portion of the fixing rib  21  where the lead wire-through hole  23  is formed, smaller than the side of the fixing rib  21  which contacts the connection tab  40 . This is because the coating of the lead wire  50  may peels off by the fixing rib  21 , when shock is applied to the battery cells due to drop etc. 
     Further, the guide grooves  24  through which the lead wire  50  adjacent the fixing ribs  21  can pass may be further formed on the first extender and the second extender  20   b ,  20   c . That is, the guide grooves  24  for guiding the lead wire  50  from the first extender and the second extender  20   b ,  20   c  of the holder case  20  when connecting the lead wire  50  passing through the lead wire-through hole  23  from the battery cells  10  to the protection circuit module  30  may be further formed. Protruding ribs  25 ,  25 ′ fixing or supporting the lead wire  50 , which passes through, may be further formed inside the guide grooves  24 . 
     The protruding rib  25  shown in  FIG. 4A  may protrude at a constant thickness on both inner sides of the guide groove  24 . Therefore, it is possible for the lead wire  50  inserted in the guide groove  24  to be inhibited from being separated outside. The protruding rib  25 ′ shown in  FIG. 4B  may have a shape that decreases in thickness toward the inside of the guide groove  24 . Therefore, the lead wire  50  press-fitted in the guide groove  24  can be seated inside the guide groove  25  without contacting the protruding rib  25 ′. That is, the lead wire  50  can move inside the protruding rib  25 ′, but cannot be separated outside from the guide groove  24  by the protruding rib  25 ′. Further, though not shown, the protruding rib may protrude only at the inlet of the guide groove. 
     A guide member  26  fixing the lead wire  50  not to be horizontally move may be further formed at the cover  20   a  of the holder case  20 . The guide members  26 ,  26 ′ described above are show in detail in  FIGS. 5A and 5B . First, referring to  FIG. 5A , the guide member  26  that guides the lead wire  50  is further formed at the cover  20   a  (see  FIG. 1 ) of the holder case  20 . The guide member  26  is formed in a T-shape to fix the lead wire  50  not to horizontally move.  FIG. 5B  is a perspective view showing a guide member different from that shown in  FIG. 5A . Referring to  FIG. 5B , the guide member  26 ′ may be formed in an inverse L-shape with a hook  27  at the end. Therefore, similar to the guide member  26  of  FIG. 5A , it can fix the lead wire  50  not to horizontally move while guiding the lead wire. 
     Further, the lead wire  50 , in one embodiment, is coated with a vinyl tube and connects the protection circuit module  30  with the battery cell  10 . In this configuration, the lead wire  50  may be a monitoring lead wire that can measure cell balancing. The lead wire  50  may be connected with the connection tab  40  at one end and with the protection circuit module  30  at the other end. In this configuration, one end of the lead wire  50  may be connected with the connection tab  40  by soldering. It is possible to check whether current flows well to the battery cells  10 , using the lead wire  50 . 
       FIG. 6  is a perspective view showing the battery pack with an insulating sheet according to one embodiment of the present invention. 
     Referring to  FIG. 6 , the insulating sheet  60  is provided to prevent or inhibit contact between the connection tab  40  (see  FIG. 1 ) connected with the first an second poles of the battery cells  10  by welding and the external case  100  (see  FIG. 7 ) which is the finish material. It is preferable that the insulating sheet  60  is made of a material having high thermal resistance in order to be prevented from being damaged by heat generated when current flows through the connection tab  40  or the lead wire  50 . 
     Further, the protection module  30  may be installed at the cover  20   a  of the holder case  20 . Electronic components are mounted on the protection circuit module  30 , thereby implementing a protection circuit. The protection circuit module  30  is fixed to the holder case  20  by bolts, but may be fixed by other fasteners. 
       FIG. 7  is a perspective view showing a battery back equipped with an external case according to one embodiment of the present invention. 
     Referring to  FIG. 7 , an external case  100  may be further provided around the holder case  20  covering the battery cell  10 . The external case  100  may be divided into a first case  100   a  and a second case  100   b , which are fastened to each other. The first case  100   a  and the second case  100   b  may be fastened by a groove  101   a  and a protrusion  101   b , which are formed at the cases, respectively. 
     Though not shown in the figures, the first case  100   a  and the second case  100   b  may be fixed by bolts or fitting. Further, a groove and a protrusion for combination may be formed on the inner sides facing each other of the first case  100   a  and the second case  100   b.    
     In this configuration, the inner surface of the case  100   a  which contacts the first extender  20   b  of the holder case  20  may be formed in order not to interfere with the guide groove  24 . That is, it is formed such that the lead wire  50  inserted in the guide groove  24  does not directly contact the first case  100   a . Therefore, it is possible to prevent the coating of the lead wire  50  from peeling off. 
     Although the cylindrical battery cells are used in the embodiments of the present invention, it should be noted that other shapes of battery cells may be used. 
     Although the spirit of the present invention was described in detail with reference to the preferred embodiments, it should be understood that the embodiments are provided only for explaining the present invention and the present invention is not limited thereto. Further, it should be understood that the present invention may be modified in various ways by those skilled in the art, without departing from the scope of the present invention. 
     The scope of the present invention described above is determined by the following claims and not limited to the detailed description described herein, and equivalent changes and modifications within claims are included in the spirit and scope of the present invention.