Abstract:
A battery module includes a plurality of unit batteries disposed apart at intervals and a plurality of barriers interposed between the unit batteries. Each of the barriers includes a base supported on the unit battery and a plurality of protrusions extending from the base and contacting the unit battery. The protrusions are formed of an insulation material. In addition, the protrusions may be fixed onto the base in a staggered arrangement along columns and rows so that a certain angular arrangement between the alignment of protrusions is achieved, thereby maximizing cooling efficiency.

Description:
CLAIM OF PRIORITY  
       [0001]     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for SECONDARY BATTERY MODULE AND WALL OF SECONDARY BATTERY MODULE earlier filed in the Korean Intellectual Property Office on the 14 th  of Apr. 2005 and there duly assigned Serial No. 10-2005-0030994.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Technical Field  
         [0003]     The present invention relates to a battery module and, more particularly, to a battery module having a plurality of unit batteries and interposed barriers.  
         [0004]     2. Related Art  
         [0005]     Unlike a primary battery, the rechargeable battery may be recharged. Lower power batteries are used for various portable electronic devices such as cellular phones, laptop computers, and camcorders. Bulk size batteries are used as the power source for motor drive, such as in hybrid electric vehicles.  
         [0006]     Depending on the external shape, rechargeable batteries may be classified into different types, for example, prismatic and cylindrical batteries. When they are used for motor drives for machines requiring a high power source, such as the hybrid electric vehicles, the rechargeable batteries may form a battery module of high power.  
         [0007]     The battery module is formed by serially connecting several rechargeable batteries (hereinafter “unit batteries”), and each of the unit batteries includes an electrode assembly in which a separator is interposed between a positive electrode and a negative electrode. The electrode assembly is inserted inside a case, and a cap assembly is assembled with the case to seal the case. The cap assembly can include terminals which are disposed so as to extend from the inside to the outside of the case, and which are electrically connected to the positive electrode and the negative electrode, respectively.  
         [0008]     If the unit batteries are prismatic type batteries, the unit batteries are arranged so as to alternate positive and negative terminals of one unit battery projected from the upper portion of the cap assembly with the positive and negative terminals of an adjacent unit battery. Adaptors of the electric conductor are typically mounted on the threaded negative and positive terminals so that they are electrically connected with each other to form the battery module.  
         [0009]     Since the battery module connects several to tens of unit batteries to form one battery module, there is a need to efficiently dissipate heat generated from each unit battery. In particular, when the unit batteries are used as bulk size rechargeable batteries for a motor drive, such as in electric vehicles, hybrid electric vehicles, motor scooters, and vacuum cleaners, heat dissipation is of significant importance.  
         [0010]     If heat dissipation does not occur properly in the battery module, the temperature of the battery module may increase excessively 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.  
         [0011]     Accordingly, when forming the battery module, a barrier is disposed between unit batteries, and the space formed by the barriers between the unit batteries is used not only for cooling the unit batteries, but also for preventing distortion due to heat expansion of the unit batteries.  
         [0012]     To perform such functions, the barrier needs sufficient strength, and structure for efficient heat dissipation.  
         [0013]     However, the barriers in the conventional battery module do not satisfy the above two conditions simultaneously so that there is difficulty in forming battery modules of the quality which consumers expect.  
         [0014]     That is, if the barriers provide sufficient strength, the manufacturing cost is increased and there is a restriction in designing a passage of cooling air. Alternatively, if the barriers are formed so as to have high cooling efficiency, they tend to exhibit structural weakness.  
       SUMMARY OF THE INVENTION  
       [0015]     The present invention provides a battery module including a barrier which has sufficient strength for maintaining a unit battery shape, and which can efficiently control the unit battery temperature.  
         [0016]     According to an embodiment of the present invention, a battery module comprises a plurality of unit batteries disposed apart at intervals, and a plurality of barriers interposed between the unit batteries, wherein each of the barriers includes a base supported on the unit battery and a plurality of protrusions extending from the base and contacting the unit battery, the protrusions being formed of an insulation material.  
         [0017]     The base may be a plate or a bar.  
         [0018]     Preferably, the protrusions are formed of ceramic or plastic, and/or are formed on only one surface of the plate.  
         [0019]     The base may be formed of a conductive material. Alternatively, the base may be formed of an insulation material.  
         [0020]     The protrusions may be separately formed and fixed on the base. In this case, the protrusions may be fixedly inserted in grooves formed on the base.  
         [0021]     Alternatively, the base may be integrally formed with the protrusions.  
         [0022]     Preferably, the protrusions have cross-sections which are circular, trapezoidal or rectangular in shape.  
         [0023]     Preferably, the battery module is used as a power source for driving a motor.  
         [0024]     Preferably, the protrusions are fixed on the base in a staggered arrangement along columns and rows. In this case, an angle between a first imaginary extending line, which connects a first protrusion disposed at an intersection point of a first column and a first row to a second protrusion disposed at an intersection point of a second column adjacent to the first column and a second row adjacent to the first row, and a second imaginary extending line, which connects the first protrusion to a third protrusion disposed at an intersection point of the second column and a third row adjacent to the first row at an opposite side of the second row, is preferably within a range of 30-150°. More preferably, the angle is within a range of 45-60°. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily apparent as the present invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:  
         [0026]      FIG. 1  is a cross-section side view of a battery module according to an embodiment of the present invention;  
         [0027]      FIG. 2  is a perspective view of a barrier of the battery module of  FIG. 1 ;  
         [0028]      FIG. 3  is a cross-section view of the barrier of  FIG. 2 ;  
         [0029]     FIGS.  4  thru  6 ,  7 A thru  7 D,  8 A thru  8 D, and  9 A thru  9 H are views of a variety of modified examples of the barrier of  FIG. 2 ; and  
         [0030]      FIG. 10  is a view illustrating the operation of the barrier depicted in  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     The present invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the present invention are shown.  
         [0032]      FIG. 1  is a cross-section side view of a battery module according to a first embodiment of the present invention.  
         [0033]     Referring to  FIG. 1 , a battery module  10  according to the present embodiment includes a plurality of unit batteries  11   1 ,  11   2  . . .  11   n  spaced predetermined intervals apart from one another.  
         [0034]     Each unit battery in the present embodiment is a prismatic type rechargeable battery which includes a case, an electrode assembly including a positive electrode, a negative electrode, and a separator to be inserted into the case, and a cap assembly installed on the case.  
         [0035]     Barriers  20   1 ,  20   2  . . .  20   n  are disposed between the unit batteries  11   1 ,  11   2  . . .  11   n  so as to allow a coolant (e.g., air in the present embodiment) to flow between the unit batteries  11   1 ,  11   2  . . .  11   n . The barriers  20   1 ,  20   2  . . .  20   n  are attached to the unit batteries  11   1 ,  11   2  . . .  11   n  so as to support them.  
         [0036]     Such unit batteries  11   1 ,  11   2  . . .  11   n  and the barriers  20   1 ,  20   2  . . .  20   n  can be attached by a fastener, that is, by end plates  13  disposed at both of the outermost sides of a unit battery aggregate comprised of the unit batteries  11   1 ,  11   2  . . .  11   n  and the barriers  20   1 ,  20   2  . . .  20   n , and by restraint rods  14  combined with the end plates  13  by a screw thread so as to fix the unit batteries  11   1 ,  11   2  . . .  11   n  and the barriers  20   1 ,  20   2  . . .  20   n  in place, thereby forming an assembly.  
         [0037]     The assembly is mounted in a housing  12  having an inlet  12   a  for receiving air which cools the unit batteries  11   1 ,  11   2  . . .  11   n , and an outlet  12   b  for discharging the air.  
         [0038]     The assembly is installed in the housing  12  by detachably fixing the end plates  13  to the housing  12  with fixing elements, for example, screws and/or nuts.  
         [0039]     The inlet  12   a  is disposed on one side of the upper portion of the housing  12 , and the outlet  12   b  is disposed on one side of the lower portion of the housing  12 , the outlet  12   b  being arranged opposite to the inlet  12   a . However, such a structure of the housing  12  is only one example of the structure which the present invention can adopt, and the present invention is not limited thereto.  
         [0040]     Such a battery module  10  enables the incoming air entering the housing  12  through the inlet  12   a  of the housing  12  to flow from the upper portion to the lower portion of the housing  12 , and to exit from the housing  12  through the outlet  12   b  of the housing  12 .  
         [0041]     During this process, the air passes through the barriers  20   1 ,  20   2  . . .  20   n , and the heat generated by the unit batteries  11   1 ,  11   2  . . .  11   n  is heat-exchanged by the air, thereby cooling the unit batteries  11   1 ,  11   2  . . .  11   n .  
         [0042]     Referring to  FIGS. 2 and 3 , the barrier  20  is described in more detail. Since the barriers  20   1 ,  20   2  . . .  20   n  are identical in shape with respect to each other, only one barrier  20  will be described as an example.  
         [0043]     The barrier  20  includes a base  21  and a plurality of protrusions  22  installed on the base  22 .  
         [0044]     In this embodiment, the base  21  is formed of a plastic material and has a surface area the same as a side surface of the unit battery  11 . Each protrusion  22  is formed in a spherical shape. The protrusions  22  are attached to a surface of the base  21 , and are spaced apart from each other by a predetermined distance. In addition, the protrusions  22  may be formed of an insulation material, such as ceramic.  
         [0045]     In order to attach the protrusions  22  to the base  21 , a plurality of grooves  23 , each having a shape corresponding to that of the protrusion  22 , are formed on the surface of the base  21 , and the protrusions  22  are fixedly inserted in the grooves  23 .  
         [0046]     The fixing of the protrusions  22  in the grooves  23  may be achieved by inserting the protrusions  22  in the grooves  23  in an interference fit manner or by adhesive.  
         [0047]     When the protrusions  22  are fixed in the grooves  23 , a height h ( FIG. 3 ) of the protrusion  22  directly affects a thickness t of the barrier  20 , i.e., an interval between the unit batteries  11 . Thus, the height h of the protrusion  22  may be properly adjusted according to the design of the battery module.  
         [0048]     Referring back to  FIG. 1 , when the battery module  10  is formed by disposing the barriers  20   1 ,  20   2  . . .  20   n  between the unit batteries  11   1 ,  11   2  . . .  11   n , first surfaces of the bases  21  closely contact first side surfaces of the unit batteries  11   1 ,  11   2  . . .  11   n  while protrusions  22  protruding from second surfaces of the bases  21  closely contact second side surfaces of the unit batteries  11   1 ,  11   2  . . .  11   n  so as to uniformly maintain intervals between the unit batteries  11   1 ,  11   2  . . .  11   n .  
         [0049]     Therefore, predetermined intervals are maintained between the unit batteries  11   1 ,  11   2  . . .  11   n , between the end plate  13  and the unit battery  11 , and between the end plate  13  and the unit battery  11   n . Thus, the incoming air entering the housing  12  passes through spaces defined between the protrusions  22  to dissipate the heat generated by the unit batteries  11   1 ,  11   2  . . .  11   n .  
         [0050]     Since the protrusions  22  of the barriers  20   1 ,  20   2  . . .  20   n  and the base  21  closely contact the unit batteries  11   1 ,  11   2  . . .  11   n , they can function to support the unit batteries  11   1 ,  11   2  . . .  11   n  against an expanding force which would otherwise deform the unit batteries  11   1 ,  11   2  . . .  11   n  when the battery module is being used.  
         [0051]     At this point, the protrusions  22  are uniformly distributed on the supporting portions of the unit batteries  11   1 ,  11   2  . . .  11   n  so as to support the unit batteries  11   1 ,  11   2  . . .  11   n , and the supporting force applied to the unit batteries  11   1 ,  11   2  . . .  11   n  is enhanced, thereby preventing the unit batteries  11   1 ,  11   2  . . .  11   n  and the barriers  20   1 ,  20   2  . . .  20   n  from being deformed.  
         [0052]     Furthermore, since the protrusions  22  are formed of insulation material, such as ceramic, there is no need to dispose separate insulation members for preventing a short circuit between the unit batteries  11   1 ,  11   2  . . .  11   n .  
         [0053]     If required, the bases  21  of the barriers  20   1 ,  20   2  . . .  20   n  may also be formed of an insulation material, such as ceramic.  
         [0054]      FIGS. 4 and 5  are cross-section views of modified examples of the barrier.  
         [0055]      FIG. 4  shows a case wherein a barrier  20 ′ includes a base  21 ′ and a plurality of protrusions  22 ′, each protrusion  22 ′ having a trapezoidal cross-section. The protrusions  22 ′ are fixedly inserted in grooves  23 ′ formed on the base  21 ′.  
         [0056]     The protrusions may be formed in a variety of other shapes in addition to the above shape.  
         [0057]      FIG. 5  shows a case wherein a barrier  20 ″ includes a base  21 ″ and a plurality of protrusions  22 ″, each protrusions  22 ″ having a rectangular cross-section. The protrusions  22 ″ are fixedly inserted in grooves  23 ″ formed on the base  21 ″.  
         [0058]      FIG. 6  is an exploded perspective view of another modified example of the barrier.  
         [0059]     In this modified example, the barrier  30  includes a base  32  formed of metal, such as aluminum or cooper, having a high thermal conductivity, and a plurality of bars  34  are attached to protrude from a surface of the base  32 . The bars  34  are spaced apart from each other by a predetermined distance. The bars  34  have circular cross-sections. The bars  34  may be formed of an insulation material, such as ceramic.  
         [0060]     In order to attach the bars  34  to the base  32 , a plurality of grooves  36 , each having a shape corresponding to that of the bar  34 , are formed on the surface of the base  32 , and the bars  34  are fixedly inserted in the grooves  36 .  
         [0061]     The fixing of the bars  34  in the grooves  36  may be achieved by inserting the bars  34  in the grooves  36  in an interference fit manner or by adhesive.  
         [0062]     The cross-sections of the bars may be formed in a variety of shapes, such as a trapezoidal shape, a rectangular shape or an oval shape, in addition to the circular shape. In this case, the grooves are formed to correspond to the shape of the bars.  
         [0063]     Since the function of the barriers  30  of this embodiment is identical to that of the barrier of the foregoing embodiments, a detailed description thereof will be omitted herein.  
         [0064]      FIGS. 7A  thru  7 D are cross-section views of other modified examples of the barrier.  
         [0065]     Referring to  FIGS. 7A  thru  7 D, barriers  42 ,  44 ,  46  and  48  have protrusions  42   a ,  44   a ,  46   a  and  48   a , respectively, and bases  42   b ,  44   b ,  46   b  and  48   b , respectively. The protrusions  42   a ,  44   a ,  46   a  and  48   a  are integrally formed with the bases  42   b ,  44   b ,  46   b  and  48   b , respectively. The bases and the protrusions are formed of an insulation material, such as ceramic or plastic.  
         [0066]     The protrusions  42   a ,  44   a ,  46   a , and  48   a  may be hollow as shown in the drawings or they may be solid.  
         [0067]      FIGS. 8A  thru  8 D are cross-section views of other modified examples of the barrier.  
         [0068]     Referring to  FIGS. 8A  thru  8 D, additional plates  50   b ,  52   b ,  54   b  and  56   b  are attached to front ends of protrusions  50   a ,  52   a ,  54   a , and  56   a , respectively, of barriers  50 ,  52 ,  54 , and  56 , respectively, which are identical to those depicted in  FIGS. 7A  thru  7 D.  
         [0069]     In this embodiment, since the plates  50   b ,  52   b ,  54   b , and  56   b , instead of the protrusions, contact the side surfaces of the unit batteries, the areas of contact with the unit batteries increase, thereby further enhancing the supporting force against the unit batteries. The plates  50   b ,  52   b ,  54   b , and  56   b  are preferably formed of the same material as the protrusions.  
         [0070]      FIGS. 9A  thru  9 H are cross-section views of other modified example of the barrier.  
         [0071]     Referring to  FIGS. 9A  thru  9 H, barriers  60 ,  62 ,  64 ,  66 ,  68 ,  70 ,  72 , and  74  are formed by combining two barriers of the foregoing embodiments to increase the strength thereof.  
         [0072]     When arranging the protrusions on the base, the protrusions are arranged to satisfy the following conditions. This will be described with reference to the barrier of  FIG. 10 .  
         [0073]     Referring to  FIG. 10 , the protrusions  22  are fixed on the base  21  in a staggered arrangement along columns and rows. At this point, an angle β between a first imaginary line X, which connects a first protrusion  22   a  disposed at an intersection point of a first column and a first row to a second protrusion  22   b  disposed at an intersection point of a second column adjacent to the first column and a second row adjacent to the first row, and a second imaginary line Y, which connects the first protrusion  22   a  to a third protrusion  22   c  disposed at an intersection point of the second column and a third row adjacent to the first row at an opposite side of the first row relative to the second row, is preferably set to satisfy the following condition: 
 
30°≦β≦150°
 
         [0074]     More preferably, the angle β is set to satisfy the following condition: 
 
45°≦β≦60°
 
         [0075]     With the above-described arrangement of the protrusions  22   a ,  22   b  and  22   c , the air flowing into the barrier  20  through the inlet  12   a  of the housing  12  of  FIG. 1  collides with the protrusions  22   a ,  22   b  and  22   c  of  FIG. 10 , and is dispersed toward both sides of the protrusions  22   a ,  22   b  and  22   c  (see arrows {circle around ( 1 )} and {circle around ( 2 )} of  FIG. 10 ).  
         [0076]     That is, the air collides with the protrusions  22   a ,  22   b  and  22   c , and changes its direction of flow toward both sides of the protrusions  22   a ,  22   b  and  22   c . At this point, the speed of air flow would normally be a factor affecting the cooling efficiency of the unit battery.  
         [0077]     That is, when the air passing through the barrier  20  cannot flow at a proper speed, the pressure drop in the barrier  20  would normally increase, and thus the air flow resistance in the housing  12  would normally increase. This would result in deterioration of the cooling efficiency for the unit battery. Furthermore, when the air cannot properly disperse in the barrier  20 , heat exchange cannot be effectively realized, and thus the cooling efficiency for the unit battery would normally deteriorate. Furthermore, when a unit, such as a cooling fan, is more strongly operated to increase the speed of flow of the air, the unit may be overloaded which would normally cause a variety of other problems.  
         [0078]     However, to avoid and solve these problems, in the present invention, the angle β is set within the above-described range so that the air flows at the proper speed, and thus the cooling efficiency for the unit battery is maximized.  
         [0079]     It has been observed through testing that, when the angle β is less than 30°, the heat exchange efficiency is too low, and when the angle β is greater than 150°, the air flow speed is too low. However, when the angle β is set to within 30° to 150°, and preferably to within 45° to 60°, these problems are avoided, and cooling efficiency is maximized.  
         [0080]     According to the present invention, since the barriers are improved in their structures and are formed of the insulation material, short circuit between the unit batteries can be prevented. Furthermore, there is no need to provide separate insulation members, and thus the manufacturing cost of the battery module can be reduced.  
         [0081]     Moreover, since the structure of the barrier and the air flow structure of the barrier are improved, a sufficient strength of the barrier can be achieved, thereby preventing the deformation of the barrier and improving the heat-exchange efficiency.  
         [0082]     In addition, since the direction of flow of the air passing through the barrier can be freely designed, the design range of the battery module can be expanded.  
         [0083]     The battery module can be used for motor drive of equipment requiring high power characteristics such as HEVs (Hybrid Electric Vehicles), EVs (Electric Vehicles), cordless vacuum cleaners, motorbikes, electric scooters, and so on.  
         [0084]     It should also be noted that the base of the barrier may be provided in the form of a plate, or in the form of a bar integrally formed with or assembled with the protrusions.  
         [0085]     While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the present 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.