Abstract:
A battery module according to one aspect of the present invention includes: a plurality of rechargeable batteries; a housing configured to house the plurality of rechargeable batteries and having a first fastening portion; a cover configured to couple to the housing and having a second fastening portion configured to couple to the first fastening portion by a tight fitting; and an elastic member configured to fit between the first and second fastening portions.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0109806, filed in the Korean Intellectual Property Office on Nov. 5, 2010, the entire content of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The described technology relates to a battery module. More particularly, the described technology relates generally to a battery module having an improved housing structure. 
         [0004]    2. Description of Related Art 
         [0005]    A rechargeable battery differs from a primary battery in that it can be repeatedly charged and discharged, while the latter makes the irreversible conversion of chemical to electrical energy. The low-capacity rechargeable battery is used as the power supply for small electronic devices, such as cellular phones, notebook computers and camcorders, while the high-capacity rechargeable battery is used as the power supply for driving motors in hybrid vehicles and the like. 
         [0006]    Recently, a high power rechargeable battery that includes a non-aqueous electrolyte having a high energy density has been developed, and is constituted by a large capacity rechargeable battery in which a plurality of rechargeable batteries are coupled in series in order to use it to drive devices requiring a large amount of power, for example, motors such as for electric vehicles. 
         [0007]    In addition, a large capacity rechargeable battery generally includes a plurality of rechargeable batteries that are coupled in series, and the rechargeable battery may be formed to have cylindrical shapes or angular prismatic shapes. The rechargeable batteries are installed in a housing and thus the housing is sealed to prevent or block external foreign matter from entering thereinto. However, it is impossible to completely seal the housing because a cover is detachably formed for maintenance of the housing. 
         [0008]    An external short circuit may be caused when the external foreign matter such as water enters the housing, and instantaneous current flow may cause the rechargeable batteries to explode or catch fire. 
         [0009]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0010]    Aspects of embodiments of the present invention are directed toward a battery module with improved safety. 
         [0011]    A battery module according to one embodiment of the present invention includes: a plurality of rechargeable batteries; a housing configured to house the plurality of rechargeable batteries and having a first fastening portion; a cover configured to couple to the housing and having a second fastening portion configured to couple to the first fastening portion by a tight fitting; and an elastic member configured to fit between the first and second fastening portions. 
         [0012]    The first fastening portion may be formed in the shape of a protrusion along an upper side of a wall body of the housing, the second fastening portion may be formed in the shape of a groove, and the first fastening portion may have a first inclined side inclined to the upper side of the wall body. 
         [0013]    The second fastening portion may have a second inclined side contacting and inclined to the first inclined side, the second inclined side may have an incline angle that is greater than that of the first inclined side. The elastic member may be configured to be inserted between the first and second inclined sides. 
         [0014]    In addition, the first fastening portion may have an inclined side inclined to an inner side of the second fastening portion, the second fastening portion may be formed in the shape of a groove, and a root portion of the first fastening portion may be larger than an entrance portion of the second fastening portion. 
         [0015]    The first fastening portion may be formed in the shape of a groove, the second fastening portion may be formed in the shape of a protrusion along an upper side of a wall body of the housing. A cross-section of the second fastening portion may be gradually increased toward the wall body of the housing. 
         [0016]    The second fastening portion may have a cross-section that is gradually decreased toward the cover, and the second fastening portion may have an inclined side inclined to an inner side of the first fastening portion. The elastic member may be inserted between the inner side and the inclined side of the first fastening portion and the inclined side of the second fastening portion. 
         [0017]    The first fastening portion may be formed along a circumference of the housing, and the second fastening portion may be formed along a circumference of the cover. 
         [0018]    The battery module may further include a pressing member configured to press the cover to the housing. The first fastening portion and the second fastening portion may be configured to be coupled to each other by a tight fitting. 
         [0019]    The elastic member may include a material selected from the group consisting of natural rubber, silicon, polybutylene terephthalate (PBT), ethylene propylene diene monomer (EPDM), and polyamides. 
         [0020]    According to an embodiment, the elastic member is provided between the fastening portions that are coupled to each other by a tight fitting so that the housing can be stably sealed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a perspective view of a battery module according to a first embodiment of the present invention. 
           [0022]      FIG. 2  is an exploded perspective view of a housing and a cover of the battery module according to the first embodiment of  FIG. 1 . 
           [0023]      FIG. 3  is a cut-out perspective view of the cover according to the first embodiment of  FIG. 1 , viewed from the bottom thereof. 
           [0024]      FIG. 4A  is an exploded cross-sectional view of the housing and the cover according to the first embodiment of  FIG. 1 . 
           [0025]      FIG. 4B  is a partial cross-sectional view of the members shown in  FIG. 4A  in the combined state. 
           [0026]      FIG. 5A  is an exploded perspective view of a housing and a cover according to a second embodiment of the present invention. 
           [0027]      FIG. 5B  is a partial cross-sectional view of the members shown in  FIG. 5A  in the combined state. 
           [0028]      FIG. 6A  is an exploded sectional view of a housing and a cover according to a third embodiment of the present invention. 
           [0029]      FIG. 6B  is a partial cross-sectional view of the members shown in  FIG. 6A  in the combined state. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0030]    The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0031]    The drawings and description are to be regarded as illustrative in nature and not restrictive. Further, like reference numerals designate like elements throughout several embodiments. A first embodiment will be representatively described, and the components other than those of the first embodiment will be described in other embodiments. 
         [0032]    Throughout this specification and the claims that follow, when it is described that an element is “coupled” to another element, the element may be “directly coupled” to the other element or “electrically coupled” to the other element through one or more third elements. In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
         [0033]      FIG. 1  is a perspective view of a battery module according to a first embodiment of the present invention, and  FIG. 2  is an exploded perspective view of a housing and a cover of the battery module according to the embodiment of  FIG. 1 . 
         [0034]    Referring to  FIGS. 1 and 2 , a battery module  101  according to the first embodiment includes a plurality of rechargeable batteries  20 , a housing  30  in which the plurality of rechargeable batteries  20  are installed, and a cover  40  combined with the housing  30 . 
         [0035]    Each rechargeable battery  20  of the plurality of rechargeable batteries  20  installed in the housing  30  is exemplarily described as a quadrangle-type lithium ion rechargeable battery. However, without being limited thereto, the present invention may be applicable to various types of batteries such as a lithium polymer battery, a cylindrical battery, and the like. 
         [0036]    The rechargeable battery  20  includes a positive terminal  21 , a negative terminal  22 , and a vent member  27 , which is configured to open at a set or predetermined pressure to release gas. Also, the vent member  27  is configured to break when the internal pressure of the rechargeable battery is increased to or above a set or predetermined level to provide a path for releasing an internal gas to the outside atmosphere. The vent member  27  of the rechargeable battery  20  includes a notch that is opened at a set or predetermined pressure to release the gas therethrough. 
         [0037]    The rechargeable battery  20  includes a case  28  in which an electrode assembly is installed, and the positive terminal  21  and the negative terminal  22  protrude to the outside of the case  28 . 
         [0038]    The case  28  is formed in a substantially cubic prismatic shape. In one embodiment, the case  28  is formed from a metal such as aluminum or an aluminum alloy. The positive terminal  21  and the negative terminal  22  are formed in an upper portion of the rechargeable battery  20 . The positive terminal  21  is electrically connected with a positive electrode of the electrode assembly and the negative terminal  22  is electrically connected with a negative electrode of the electrode assembly. 
         [0039]    The plurality of rechargeable batteries  20  are stacked or layered in parallel with each other in a side direction (x-axis direction of  FIG. 1 ) such that wide front sides of the rechargeable batteries  20  are arranged opposite to each other. Positive and negative electrode terminals  21  and  22  of neighboring rechargeable batteries  20  are arranged in an alternating manner. 
         [0040]    The plurality of rechargeable batteries  20  arranged in parallel with each other are electrically coupled in series by a plurality of bus-bars  15 . That is, each bus-bar  15  of the plurality of bus bars is provided at a positive electrode terminal  21  of one rechargeable battery  20  and a negative electrode terminal  22  of an adjacent rechargeable battery  20 . The bus-bar  15  is formed in a plate shape, and is fixed to the positive and negative electrodes  21  and  22  by a nut secured to each electrode. 
         [0041]    As shown in  FIG. 2 , the housing  30  is formed in a substantially rectangular prismatic shape and defines an inner space. The housing  30  includes a bottom  31  formed in the shape of a rectangular plate and a wall body  32  extended from the bottom  31  to form an upper portion of the housing  30 . A first fastening portion  34  is formed protruding from the wall body  32 . The first fastening portion  34  is formed in the shape of a protrusion, and is extended circumferentially along the upper edge (upper side) of the wall body  32 . The first fastening portion  34  joins the upper edge of the wall body  32  at a root portion (e.g., as one body). A portion of the first fastening portion  34  farthest from the wall body  32  is an end portion. 
         [0042]    A first inclined side  341  that is at an incline to the upper side of the wall body  32  forms one side of the first fastening portion  34 , such that a cross-section of the first fastening portion  34  is gradually decreased in size from the root portion to the end portion. The first inclined side  341  forms an outward-facing side of the first fastening portion  34 . 
         [0043]    Referring to  FIGS. 2 and 3 , the cover  40  will be described. The cover  40  includes an upper plate  41 , a first rib  42  protruding from a bottom surface of the upper plate  41  along a peripheral portion of the upper plate  41 , and a second rib  43  protruding from the bottom surface of the upper plate  41 , parallel to and separated from the first rib  42 . A second fastening portion  45  is thus formed in the shape of a groove formed along a periphery of the cover  40  between the first rib  42  and the second rib  43 . 
         [0044]    The cover  40  seals the housing  30  by being combined thereto by the second fastening portion  45  being engaged with (or fitted to) the first fastening portion  34 . A second inclined side  451  that is at an incline to the upper plate  41  forms the outer-most wall of the second fastening portion  45 . A portion of the second fastening portion  45  farthest from the upper plate  41  is an entrance portion. The second fastening portion  45  meets the upper plate  41  at a bottom portion of the second fastening portion  45  (e.g., as one body). A cross-section of the second fastening portion  45  is gradually decreased in size from the entrance portion to the bottom portion. 
         [0045]    The second inclined side  451  is configured to contact the first inclined side  341  of the first fastening portion  34 , and the second inclined side  451  is steeper than the first inclined side  341 . Thereby, the thickness of the end portion of the first fastening portion  34  is smaller than that of a portion of the second fastening portion  45  that contacts the end portion of the first fastening portion  34  when the first fastening portion and the second fastening portion are engaged. Further, the thickness of the root portion of the first fastening portion  34  is larger than that of the entrance portion of the second fastening portion  45 . 
         [0046]    Accordingly, when the first fastening portion  34  engages the second fastening portion  45 , the root portion of the first fastening portion  34  may be tightly fitted to the entrance portion of the second fastening portion  45 . As the first fastening portion  34  and the second fastening portion  45  are further inserted, the first and second fastening portions  34  and  45  are more tightly fitted so that a stronger stress is applied between the first and second fastening portions  34  and  45 . Accordingly, sealing performance between the housing  30  and the cover  40  can be further improved. 
         [0047]    In one embodiment, an elastic member  46  is provided between the first fastening portion  34  and the second fastening portion  45 . For example, the elastic member is inserted into the second fastening portion  45 . The elastic member  46  is formed in the shape of a ring extended along a direction where the second fastening portion  45  is formed. The elastic member  46  is formed from an elastic material including at least one material selected from a group consisting of natural rubber, silicon, polybutylene terephthalate (PBT), ethylene propylene diene monomer (EPDM), and polyamides. 
         [0048]    The depth of the second fastening portion  45  is greater than the height of the first fastening portion  34 , and the elastic member  46  fills a space between the first fastening portion  34  and the second fastening portion  45  when the first fastening portion is fully engaged with the second fastening portion. Since the elastic member  46  is deformed when the first fastening portion  34  and the second fastening portion  45  are combined, the elastic member  46  fills a space between the first inclined side  341  and the second inclined side  451 . Accordingly, a firm seal can be made between the housing  30  and the cover  40 . 
         [0049]      FIG. 4A  is an exploded cross-sectional view of the housing  30  and the cover  40  according to the first embodiment of the present invention, and  FIG. 4B  is a partial cross-sectional view of the members shown in  FIG. 4A  in the combined state. 
         [0050]    As shown in  FIGS. 4A and 4B , since the cover  40  is pressured and fixed to the housing  30  by a pressing member  47 , the first and second fastening portions  34  and  45  are engaged with each other in a tight-fitting manner when the cover  40  is pressed to the housing  30 . Simultaneously or concurrently, the elastic member  46  is deformed and the root portion of the first fastening portion  34  is deformed and then further inserted into the second fastening portion  45 . In one embodiment, the pressing member  47  is in the form of a screw inserted and fixed to the housing  30  through the cover  40 . A boss  49  that guides the pressing member  47  is formed in the cover  40 . 
         [0051]    Accordingly, the space between the housing  30  and the cover  40  is sealed by the elastic member  46  filling the space between the first fastening portion  34  and the second fastening portion  45 , and a tight fit between the root portion of the first fastening portion  34  and the entrance portion of the second fastening portion  45 . Particularly, moisture cannot easily enter into the housing  30  because the first fastening portion  34  presses the elastic member  46  from below. As such, a path is extended due to an insertion structure between the first and second fastening portions so that moisture cannot enter into the housing  30 . 
         [0052]      FIG. 5A  is an exploded sectional view of a housing and a cover according to a second embodiment of the present invention, and  FIG. 5B  is a partial cross-sectional view of members shown in  FIG. 5A , in the combined state. 
         [0053]    Referring to  FIGS. 5A and 5B , a battery module according to the second embodiment is substantially the same as that of the battery module of the first embodiment, excluding configurations of a housing  50  and a cover  60 , and therefore a description for same structures will not be provided. 
         [0054]    The housing  50  is formed in the shape of a rectangular prism and defines an inner space. A first fastening portion  57  formed in the shape of a groove is formed on (into) an upper edge (upper side) of a wall body  52 . The first fastening portion  57  is formed between a first rib  53  and a second rib  54  at the upper edge (upper side) of the wall body  52 , and is formed circumferentially along a periphery of the housing  50 . 
         [0055]    A first inclined side  571  at an incline to the upper side of the wall body  52  is formed in an outer-most wall of the first fastening portion  57 . A portion of the first fastening portion  57  farthest from the wall body  52  is an entrance portion. The first fastening portion  57  meets the wall body  52  at a bottom portion of the first fastening portion  57 . A cross-section of the first fastening portion  57  is gradually decreased from the entrance portion to the bottom portion. 
         [0056]    The cover  60  is configured to combine with the housing  50 . A second fastening portion  65  extends circumferentially along the periphery of a bottom surface of the cover  60 . The second fastening portion  65  is formed in the shape of a protrusion, and is tightly fitted with the first fastening portion  57 . 
         [0057]    The cover  60  includes an upper plate  61  and the second fastening portion  65  formed in the shape of a protrusion that is extended circumferentially along the periphery of the upper plate  61  and protruded therefrom. A second inclined side  651  at an incline to the bottom surface of the upper plate  61  is formed in the second fastening portion  65 . A portion of the second fastening portion  65  farthest from the upper plate  61  is an end portion. The second fastening portion  45  meets the upper plate  61  at a root portion of the second fastening portion  65  (e.g., as one body). A cross-section of the second fastening portion  65  is gradually decreased from the root portion to the end portion. 
         [0058]    The second inclined side  651  is configured to contact the first inclined side  571  of the first fastening portion  57 , and the slope of the second inclined side  651  is less steep than that of the first inclined side  571 . Further, the root portion of the second fastening portion  65  is larger than the entrance portion of the first fastening portion  57 . In addition, the end portion of the second fastening portion  65  is larger than the bottom of the first fastening portion  57 . 
         [0059]    Thus, when the first fastening portion  57  and the second fastening portion  65  are engaged with each other, the root portion of the second fastening portion  65  may be tightly fitted to the entrance portion of the first fastening portion such that a stronger stress is applied between the first and second fastening portions  57  and  65 . 
         [0060]    An elastic member  56  provided between the first and second fastening portions  57  and  65 . In one embodiment, the elastic member  56  is inserted into the first fastening portion  57 . The elastic member  56  is formed in the shape of a ring extended along a direction where the first fastening portion  57  is formed, and is formed with an elastic material. The depth of the first fastening portion  57  is greater than the height of the second fastening portion  65 , and the elastic member  56  fills a space between the first fastening portion  57  and the second fastening portion  65  when the first fastening portion  57  and the second fastening portion  65  are engaged. Further, the thickness of a portion adjacent to the end portion of the second fastening portion  65  is smaller than the width of the first fastening portion  57  contacting same, and the thickness of the root portion of the second fastening portion  65  is larger than the width of the first fastening portion  57 , contacting the same. 
         [0061]    When the first fastening portion  57  and the second fastening portion  65  are engaged by inserting the second fastening portion  65  into the first fastening portion  57 , the elastic member  56  is deformed and thus the deformed elastic member  56  is inserted into a space between the first and second inclined sides  571  and  651 . Accordingly, a space between the housing  50  and the cover  60  can be stably sealed. 
         [0062]    The cover  60  is pressed and fixed to the housing  50  by a pressing member  67 . When the cover  60  is pressed to the housing  50 , the first and second fastening portions  57  and  65  are coupled to each other by a tight fitting such that the elastic member  56  is pressed by the first fastening portion  57  and the root portion of the second fastening portion  65  is deformed and then inserted into the entrance portion of the first fastening portion  57 . 
         [0063]    As described, according to the second embodiment, the first fastening portion  57  and the second fastening portion  65  are sealed to each other by the tight fitting and the compressed elastic member  56  fills the space between the first fastening portion  57  and the second fastening portion  65  so that the space between the housing  50  and the cover  60  can be stably sealed. 
         [0064]      FIG. 6A  is an exploded perspective view of a housing and a cover according to a third embodiment of the present invention, and  FIG. 6B  is a partial cross-sectional view of the members of  FIG. 6A , in the combined state. 
         [0065]    Referring to  FIGS. 6A and 6B , a battery module according to the third embodiment is substantially the same as the battery module according to the first embodiment, excluding configurations of a housing  70  and a cover  80 , and therefore a description for the same structures will not be provided. 
         [0066]    The housing  70  is substantially formed in the shape of a rectangular prism and defines an inner space. A first fastening portion  74  formed in the shape of a protrusion is formed circumferentially along an upper edge of a wall body  72 . The first fastening portion  74  joins the upper edge of the wall body  72  at a root portion. A portion of the first fastening portion  74  farthest from the wall body  72  is an end portion. An inclined side  741  formed at an incline to an inner side of a second fastening portion  85  is formed at a side of the first fastening portion  74  such that a cross-section of the inclined side  741  is gradually decreased toward the end portion thereof. In one embodiment, the inclined side  741  at an incline to the inner side of the second fastening portion  85 , contacting the inclined side  741 , forms an outward-facing side of the first fastening portion  74 . 
         [0067]    The cover  80  seals the housing  70  by being coupled to the housing, and the second fastening portion  85  that is coupled to the first fastening portion  74  by a tight fitting is formed in the cover  80 . The second fastening portion  85  is formed in the shape of a groove, and formed along a periphery of the cover  80 . 
         [0068]    The cover  80  includes an upper plate  81 , a first protruding rib  82  extended along the periphery of a bottom surface of the upper plate  81 , and a second protruding rib  82  parallel to and separated from the first rib  82 , such that the second fastening portion  85  is disposed between the first rib  82  and the second rib  83 . 
         [0069]    An inner side of the second fastening portion  85  is perpendicular to the upper plate  81 . A portion of the second fastening portion  85  farthest from the upper plate  81  is an entrance portion. The second fastening portion  85  meets the upper plate  81  at a bottom portion of the second fastening portion  85  (e.g., as one body). 
         [0070]    The root portion of the first fastening portion  74  is larger than the entrance portion of the second fastening portion. Accordingly, when the first and second fastening portions  74  and  85  are engaged with each other, the root portion of the first fastening portion  74  is coupled to the second fastening portion  85  by a tight fitting. In addition, the first fastening  74  is further closely sealed to the second fastening portion  85  as the first fastening portion  74  is deeply inserted into the second fastening portion  85 , and a stress applied between the first and second fastening portions  74  and  85  is further increased. 
         [0071]    An elastic member  86  is disposed between the first and second fastening portions  74  and  85 . In one embodiment, the elastic member  86  is inserted into the second fastening portion  85 . The elastic member  86  is extended in a direction to which the second fastening portion  85  is formed, and thus it has the shape of a ring. In one embodiment, the elastic member  86  is made of an elastic material. The depth of the second fastening portion  85  is larger than the height of the first fastening portion  74 , and the elastic member  86  fills a space between the first and second fastening portions  74  and  85  when the first and second fastening portions are engaged. 
         [0072]    In addition, a space between the inner side of the second fastening portion  85  and an inclined side  741  of the first fastening portion  74  is formed when the first and second portions are engaged, and the elastic member  86  is inserted into the spaced by being deformed. Accordingly, a space between the housing  70  and the cover  80  can be completely sealed. 
         [0073]    The cover  80  is pressed and fixed to the housing  70  by a pressing member  87 . When the cover  80  is pressed to the housing  70 , the first and second fastening portions  74  and  85  are coupled to each other by a tight fitting such that the elastic member  86  is deformed by being pressed by the first fastening portion  74  and the lower portion of the second fastening portion  85 , and then is inserted into the first fastening portion  74 . 
         [0074]    As described, according to the third embodiment, the first fastening portion  74  and the second fastening portion  85  are sealed to each other by the tight fitting and the compressed elastic member  86  fills the space between the first fastening portion  74  and the second fastening portion  85  so that the space between the housing  70  and the cover  80  can be stably sealed. 
         [0075]    While this invention has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 &lt;Description of certain symbols&gt; 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 101: battery module 
                 20: rechargeable battery 
               
               
                  15: bus-bar 
                 21: positive terminal 
               
               
                  22: negative terminal 
                 27: vent member 
               
               
                  28: case 
                 30, 50, 70: housing 
               
               
                  31: bottom 
                 32, 52, 72: wall body 
               
               
                 34, 57, 74: first fastening portion 
                 341, 571: first inclined side 
               
               
                 40, 60, 80: cover 
                 41, 61, 81: upper plate 
               
               
                 42, 53, 82: first rib 
                 43, 54, 83: second rib 
               
               
                 45, 65, 85: second fastening portion 
                 451, 651: second inclined side 
               
               
                 46, 56, 86: elastic member 
                 47, 67, 87: pressing member 
               
               
                 741: inclined side