Abstract:
A battery module includes unit batteries spaced apart from each other and a barrier arranged between neighboring ones of the unit batteries. The barrier includes protrusions formed on a front surface, a rear surface, or both of the barrier to form an airflow portion; and strength reinforcing portions formed on the barrier, each extending in a direction and having a channel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to and the benefit of Korean Patent Application No. 10- 2005-0034386  filed in the Korean Intellectual Property Office on Apr. 26, 2005, the entire content of which is incorporated herein by reference.  
       BACKGROUND  
       [0002]     Since several to tens of unit batteries are typically connected to each other to form one rechargeable battery module, there is a need to efficiently dissipate heat generated from each unit battery. In particular, when the battery module is applied to a hybrid electric vehicle (HEV), efficient heat dissipation is of significant importance.  
         [0003]     If the heat dissipation does not occur properly in the battery module, the temperature of the battery module may excessively increase due to the heat generated from each unit battery, and accordingly, not only the battery module but also the machines with the battery module, can malfunction. In the case of prismatic batteries, this problem will become more severe.  
         [0004]     Accordingly, when forming the battery module, barriers are disposed between unit batteries, and the space formed by the barriers between unit batteries is used not only for cooling unit batteries but also for preventing distortion due to heat expansion of the unit batteries.  
         [0005]     To perform such functions, the barriers need sufficient strength and structure for efficient heat dissipation.  
         [0006]     However, the barriers in the conventional battery module do not satisfy the above two conditions simultaneously so there is difficulty in forming battery modules of the quality which consumers expect.  
         [0007]     That is, if the barriers ensure the sufficient strength, its manufacturing cost is increased and there are limitations in designing a passage of cooling air. Alternatively, if the barriers are formed having high cooling efficiency, they tend to exhibit structural weakness.  
       SUMMARY  
       [0008]     A battery module includes unit batteries spaced apart from each other and a barrier arranged between neighboring ones of the unit batteries. The barrier includes protrusions formed on a front surface, a rear surface, or both of the barrier to form an airflow portion; and strength reinforcing portions formed on the barrier, each extending in a direction and having a channel.  
         [0009]     In one embodiment, the strength reinforcing portions are formed on opposite side edges of the barrier and the protrusions are formed between the strength reinforcing portions. Each protrusion may be formed in a truncated conical shape. In another embodiment, the protrusions are disposed apart from each other at predetermined intervals and protrude in a substantially identical direction to each other.  
         [0010]     An area where the strength reinforcing portions are formed may be about 10-30% of an overall area of the barrier.  
         [0011]     In one embodiment, the channel is formed on the front surface and the rear surface of the barrier. In another embodiment, the strength reinforcing portions include ribs arranged on the front surface, the rear surface, or both of the barrier, the ribs extending in the direction, and the channel is formed between the ribs. The ribs may protrude in a same direction as a direction in which the protrusions protrude, and a width of each of the ribs may be substantially identical to a maximum diameter of each of the protrusions.  
         [0012]     The barrier may be a first barrier, and the battery module may further include a second barrier substantially identical in structure to the first barrier. The first barrier and the second barrier may face each other such that the protrusions and strength reinforcing portions of the first barrier respectively contact the protrusions and strength reinforcing portions of the second barrier. The first barrier and the second barrier may be fixedly coupled to each other by welding.  
         [0013]     In another embodiment, at least one additional barrier has an area where a strength reinforcing portion is formed and the areas where the strength reinforcing portions of the barriers are formed gradually reduce as the respective barriers are disposed closer toward a center of the battery module. In another embodiment, at least one additional barrier has an airflow portion, and the airflow portions of the barriers gradually increase as the respective barriers are disposed closer toward a center of the battery module.  
         [0014]     The direction in which the strength reinforcing portions extend may be a substantially longitudinal or lateral direction of the battery module.  
         [0015]     The strength reinforcing portions and the airflow portion may span an entire surface of the barrier.  
         [0016]     The barrier may contact the neighboring ones of the unit batteries. In one embodiment, the protrusions contact at least one of the neighboring ones of the unit batteries. In another embodiment, the channel contacts at least one of the neighboring ones of the unit batteries. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a schematic perspective view of a battery module according to an exemplary embodiment of the present invention.  
         [0018]      FIG. 2  is a perspective view of a barrier shown in  FIG. 1 .  
         [0019]      FIG. 3  is a perspective view of a barrier according to another exemplary embodiment of the present invention.  
         [0020]      FIG. 4  is a side view of a barrier according to another exemplary embodiment of the present invention.  
         [0021]      FIG. 5  is a side view of a barrier according to another exemplary embodiment of the present invention.  
         [0022]      FIG. 6  is a side view of a barrier according to another exemplary embodiment of the present invention.  
         [0023]      FIG. 7  is a side view of a barrier according to another exemplary embodiment of the present invention.  
         [0024]      FIG. 8  is a side view of a barrier according to another exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0025]     The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.  
         [0026]      FIG. 1  shows a battery module according to an exemplary embodiment of the present invention.  
         [0027]     Referring to  FIG. 1 , a battery module  10  includes a plurality of unit batteries  11  disposed apart at predetermined intervals.  
         [0028]     Each unit battery  11  in this embodiment is a prismatic type rechargeable battery that includes an electrode assembly having a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes, and a prismatic case receiving the electrode assembly.  
         [0029]     Barriers  20  are disposed between the unit batteries  11  to maintain gaps between the unit batteries  11  and allow a coolant (e.g., air in the present embodiment) to flow between the unit batteries  11 .  
         [0030]     That is, the unit batteries  11  are spaced apart from each other by the barriers  20  to form a battery aggregate.  
         [0031]     The unit batteries  11  and the barriers  20  can closely contact each other by a fastener, that is, by end plates  13  disposed at both of the outermost sides of the battery aggregate and restraint rods  30  combined with the end plates  13  by nuts  31  to thereby form an assembly that will be received in a housing  12 .  
         [0032]     The housing  12  is provided with an air inlet  14  through which coolant (a temperature control air in this embodiment) is introduced and an air outlet  15  through which the introduced air is exhausted via the unit batteries  11 .  
         [0033]     That is, the temperature control air is introduced into the housing  12  through the air inlet  14  and passes through the barriers  20  disposed between the unit batteries  11 , in the course of which the temperature control air is heat-exchanged with the unit batteries  11 . The heat-exchanged air is then exhausted out of the housing  12  through the air outlet  15 .  
         [0034]     Such a structure of the housing  12  having the air inlet and outlet  14  and  15 , and an arrangement of the unit batteries  11  and the barriers  20  are only examples of embodiments of the battery modules that the present invention can adopt, and the present invention is not limited thereto as far as the above-described airflow can be realized.  
         [0035]     Referring to  FIG. 2 , the barrier  20  is formed of a plate  21  having an identical size to that of a side surface of the unit battery  11 . A plurality of protrusions  23  are formed on a first surface of the plate  21  to form an airflow portion  22 . The protrusions  23  are spaced apart from each other by a predetermined distance. Strength reinforcing portions  24  having a plurality of channels  25  are formed on both longitudinal side edges of the plate  21 .  
         [0036]     In this embodiment, the strength reinforcing portions  24  are formed by bending the plate  21  such that strips are formed along a longitudinal axis (X-axis as shown in the drawing) of the barrier  20 . The strips define the channels  25  on the first and second surfaces of the barrier  20 .  
         [0037]     Referring to  FIGS. 1 and 2 , when the barrier  20  is thus disposed between the unit batteries  11 , extreme ends of the protrusions  23 , surfaces of the strength reinforcing portion  24 , a second surface of the barrier  20 , which is opposite to the first surface, contact the surfaces of the adjacent unit batteries  11  to thereby support the adjacent unit batteries  11  and maintain an interval between the adjacent unit batteries. In this state, the air effectively flows through the airflow portion  22  defined between the protrusions  23 .  
         [0038]     Each protrusion  23  is formed in a truncated conical shape, a diameter of which increases toward the plate  21 . Since an interval between the adjacent unit batteries  11  is affected by a height of the protrusion  23 , the height of the protrusion  23  is properly set according to a design of the battery module.  
         [0039]     As described above, when the barrier  20  is disposed between the adjacent unit batteries  11 , the protrusions  23  of the barrier  20  support the unit battery  11  to prevent the unit battery  11  from deforming.  
         [0040]     In addition, the strength reinforcing portions  24  also support the adjacent unit batteries  11  and allow the air to effectively flow through the channels  25 , thereby efficiently dissipating the heat generated from the unit batteries  11 .  
         [0041]     With the above-described structure of the barrier  20 , not only the strength of the barrier  20  but also the cooling efficiency of the unit battery  11  can be enhanced as compared with a conventional barrier having only protrusions or only ribs.  
         [0042]      FIG. 3  is a perspective view of a barrier according to another exemplary embodiment of the present invention.  
         [0043]     Referring to  FIG. 3 , a barrier  120  is formed of a plate  121  having an identical size to a side surface of the unit battery. A plurality of protrusions  123  are formed on a first surface of the plate  121 . The protrusions  123  are spaced apart from each other by a predetermined distance to form an airflow portion therebetween.  
         [0044]     Strength reinforcing portions  124  each having ribs  126  are formed on longitudinal side edges of the first surface of the plate  121  and extend along a longitudinal axis (X-axis in the drawing). Channels  125  are formed between the ribs  126 .  
         [0045]     The rib  126  is not limited to a specific structure. For example, a width of the rib may be identical to a maximum diameter of the protrusion  123 . However, the widths of the ribs may be different from each other.  
         [0046]     In addition, distances between the ribs  126  may be identical to or different from each other.  
         [0047]     When the barrier  120  is disposed between the adjacent unit batteries, top surfaces of the ribs  126  and projections  123  contact a facing surface of the unit battery to support the unit battery. In this state, the air can effectively flow through the channels  125  and the airflow portion  122  to thereby efficiently dissipate the heat generated from the unit batteries.  
         [0048]     At this point, considering that an amount of heat generated at a center portion of the unit battery is greater than that of heat generated at a periphery portion of the unit battery when the unit battery is charged and discharged, the barrier  120  is designed such that an amount of air flowing through the airflow portion  122  is greater than that of air flowing through the channels  125 .  
         [0049]     However, since the strength reinforcing portion  124  formed on the longitudinal side edges of the barrier  120  is greater in a bending stress that the airflow portion  122  formed by the protrusions  123 , the deformation of the barrier  120 , which is caused by a stress concentration generated locally on the end plates by a restraint force of the nut fixing the restraint rod to the end plates, can be prevented.  
         [0050]     In this embodiment, an area where the protrusions  123  are formed is about 70-90% of an overall area of the first surface of the barrier  120  while an area of the longitudinal side edges where the ribs  124  are formed is about 10-30% of the overall area of the first surface of the barrier  120 .  
         [0051]     When the area where the protrusions  123  are formed is more than 90% of the overall area of the first surface, the overall strength of the barrier  120  may be deteriorated. When the area of the longitudinal side edges is more than 30% of the overall area of the first surface of the barrier  120 , the overall cooling efficiency of the barrier  120  may be deteriorated.  
         [0052]     With the above-described structure of the barrier  120 , not only the strength of the barrier  120  but also the cooling efficiency of the unit battery can be enhanced as compared with a conventional barrier having only protrusions or only ribs.  
         [0053]      FIGS. 4 and 5  show barriers according to other exemplary embodiments of the present invention.  
         [0054]     In these embodiments, two sub-barriers each having the airflow portion and the strength reinforcing portions that are described in the foregoing embodiments of  FIGS. 2 and 3  are disposed symmetrically and contact each other to form a barrier.  
         [0055]     In these embodiments, the facing sub-barriers are identical in the structure of the airflow portion and the strength reinforcing portions to each other.  
         [0056]     That is,  FIG. 4  shows an exemplary embodiment where a barrier  220  includes two sub-barriers  230 , each identical to that of  FIG. 2 . The sub-barriers  230  face symmetrically such that strength reinforcing portions  240  and protrusions  250  of one of the sub-barriers  230  respectively contact strength reinforcing portions  240  and protrusions  250  of the other of the sub-barriers  230 .  
         [0057]      FIG. 5  shows an exemplary embodiment where a barrier  320  includes two sub-barriers  330 , each identical to that of  FIG. 3 . The sub-barriers  330  face symmetrically such that strength reinforcing portions  340  and protrusions  350  of one of the sub-barriers  330  respectively contact strength reinforcing portions  240  and protrusions  250  of the other of the sub-barriers  330 .  
         [0058]     The sub-barriers  230  ( 330 ) are fixedly coupled to each other by laser-welding.  
         [0059]     According to the embodiments of  FIGS. 4 and 5 , the airflow passages are enlarged to more effectively dissipate the heat generated from the unit batteries.  
         [0060]      FIG. 6  shows a battery module according to another embodiment of the present invention.  
         [0061]     Referring to  FIG. 6 , a battery module  400  of this embodiment is basically identical to that of  FIG. 1 . However, in this embodiment, areas of longitudinal side edges where strength reinforcing portions  404  of barriers  402  are formed are gradually reduced from both sides of the battery module  400  toward a center of the battery module  400  while areas where protrusions  406  forming airflow portion of the barriers  402  are gradually increased toward the center of the battery module  400 .  
         [0062]     That is, since a stress applied to end plates  410  by nuts  408  is gradually reduced toward the center of the battery module  400 , the areas of the longitudinal side edges where the strength reinforcing portions  404  are formed are gradually increased toward the both sides of the battery module  400  to prevent the barriers  402  from deforming.  
         [0063]     Furthermore, since an amount of heat generated by unit batteries  412  is gradually increased toward the center of the battery module  400 , the areas where the protrusions  406  forming the airflow portion are gradually increased toward the center of the battery module  400 . Therefore, the unit batteries  412  of the battery module  400  can be uniformly cooled.  
         [0064]     As shown in  FIGS. 7 and 8 , strength reinforcing portions  500  and  502  may not be formed on the longitudinal side edges but on lateral side edges of barriers  504  and  506  along a lateral direction (Y-axis in the drawings).  
         [0065]     According to the embodiments of the present invention described above, by improving the structure of the barriers, the strength of the barriers can be enhanced to prevent the unit battery from deforming and the heat dissipation efficiency of the battery module can be improved.  
         [0066]     The battery module according to these embodiments of the present invention may be used as the power source for motor driving devices, such as the hybrid electric vehicles, electric vehicles, wireless vacuum cleaners, motorbikes, or motor scooters.  
         [0067]     Although exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.