Abstract:
A rechargeable battery pack and a method for separating a core pack from a case make it possible to easily separate the core pack from the case without causing any damage to the surface of the core pack. A core pack may need to be separated from the case during a process for forming a battery pack if it is improperly or insecurely fastened initially. The rechargeable battery pack includes a core pack that has an electrode assembly composed of a positive electrode plate, a separator, and a negative electrode plate. The core pack further comprises a sheath member for sealing the electrode assembly together with an electrolyte and a protective circuit module that is fastened on the exterior of the sheath member while being coupled to the electrode assembly. The rechargeable battery pack also includes a case that is adapted to seat and fix the core pack thereon that has at least one trench formed on the bottom surface on which the core pack is seated. In addition, the battery pack includes an adhesive for gluing the core pack to the bottom surface of the case and a cover for covering the case and protecting the core pack from its external surroundings.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to and the benefit of Korean Patent Application No. 2004-0039167 filed on May 31, 2004, which is hereby incorporated by reference for all purposes as if fully set forth herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the invention  
         [0003]     The present invention relates to a rechargeable battery pack and a method for easily separating a core pack from a case without causing any damage to the surface of the core pack.  
         [0004]     2. Description of the Prior Art  
         [0005]     As generally known in the art, a rechargeable battery pack refers to a battery that is used as a power source in a device and is also called an “auxiliary battery.” 
         [0006]     A battery pack generally comprises a core pack that has an electrode assembly, an electrolyte, a sheath member for sealing the electrode assembly and the electrolyte, and a protective circuit module that is positioned on the surface of the core pack. A battery pack further comprises a case on which the core pack is seated, an adhesive for gluing the core pack to the case, and a cover for the case.  
         [0007]     The core pack of a battery pack may be glued to its casein an incorrect position due to a defect of the gluing equipment, an error in positioning the adhesive, or an error in the alignment of the core pack and the case. If incorrectly glued to the case, the core pack may vibrate inside the case after the battery pack fully assembled and may generate a noise.  
         [0008]     When the core pack is improperly glued to the case, the core pack must be separated from the case and glued again. However, the separation process is hard to perform because the adhesion force of the adhesive is very strong. Even after the separation process, remnants of the used adhesive may remain on the core pack and the case. This makes the regluing processes more difficult.  
         [0009]     Furthermore, the surface of the core pack may be damaged during the separation process. This may degrade the appearance of the core pack or render it unusable. In addition, the surface of the sheath member may bulge or deform because it is not easily separated from the adhesive. Alternatively, the sheath member may fracture and cause the internal electrolyte to leak.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention provides a rechargeable battery pack that allows the core pack to easily be separated from the case.  
         [0011]     The present invention also provides a method for easily separating the core pack from the case.  
         [0012]     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.  
         [0013]     The present invention discloses a rechargeable battery pack that comprises a core pack that has an electrode assembly that comprises a positive electrode plate, a separator, and a negative electrode plate, a sheath member that seals the electrode assembly together with an electrolyte, and a protective circuit module that is fastened to the exterior of the sheath member while being coupled to the electrode assembly. The battery pack further comprises a case that is adapted to seat and fix the core pack thereon and has at least one trench formed on its bottom surface on which the core pack is seated. In addition, the battery pack comprises an adhesive for gluing the core pack to the bottom surface of the case and a cover for covering the case and protecting the core pack from external environments.  
         [0014]     The present invention also discloses a rechargeable battery pack comprising a voltage generation means for generating a predetermined voltage, a casing means for seating the voltage generation means on its bottom surface which has at least one trench formed thereon, a gluing means for gluing the voltage generation means to the bottom surface of the casing means, and a covering means for covering the casing means and protecting the voltage generation means from external environments.  
         [0015]     The present invention also discloses a method for separating a core pack from a case that comprises the steps of preparing a core pack that has an electrode assembly, an electrolyte, a sheath member for sealing the electrode assembly and the electrolyte. A protective circuit module is positioned on the exterior of the sheath member while being coupled to the electrode assembly. Then the core pack is glued to the bottom surface of a case using an adhesive that is interposed between them. The adhesive strength of the bond between the core pack and the case is tested. If the test result is out of an acceptable range, the core pack and the case are dipped into a solution to a predetermined depth to decrease the adhesion force of the adhesive so that the core pack may be separated from the case.  
         [0016]     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.  
         [0018]      FIG. 1A  is a perspective view that shows a rechargeable battery pack according to an exemplary embodiment of the present invention.  
         [0019]      FIG. 1B  is an exploded perspective view of the rechargeable battery pack shown in  FIG. 1A .  
         [0020]      FIG. 1C  is an exploded perspective view that shows only a core pack of the rechargeable battery pack shown in  FIG. 1B .  
         [0021]      FIG. 2A  is a perspective view that shows a rechargeable battery pack according to another exemplary embodiment of the present invention.  
         [0022]      FIG. 2B  is an exploded view of the rechargeable battery pack shown in  FIG. 2A .  
         [0023]      FIG. 3A  is a sectional view taken along line  1 - 1  of  FIG. 1A .  
         [0024]      FIG. 3B  is a sectional view that magnifies area  2  of  FIG. 3A .  
         [0025]      FIG. 3C  is a top view that shows a rechargeable battery pack according to an exemplary embodiment of the present invention.  
         [0026]      FIG. 4  is a top view that shows a rechargeable battery pack according to another exemplary embodiment of the present invention.  
         [0027]      FIG. 5  is a top view that shows a rechargeable battery pack according to another embodiment of the present invention.  
         [0028]      FIG. 6A  illustrates a method for separating a core pack from a case according to an exemplary embodiment of the present invention, wherein a rechargeable battery pack is dipped into a solution.  
         [0029]      FIG. 6B  is a sectional view taken along line  3 - 3  of  FIG. 6A . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]      FIG. 1A  is a perspective view that shows a rechargeable battery pack according to an exemplary embodiment of the present invention.  FIG. 1B  is an exploded perspective view of the rechargeable battery pack shown in  FIG. 1A .  FIG. 1   c  is an exploded perspective view that shows only a core pack of the rechargeable battery pack shown in  FIG. 1B .  
         [0031]      1 A 1 B 1 A 1 B As shown in  FIG. 1A ,  FIG. 1B , and  FIG. 1C , a rechargeable battery pack  100  according to an exemplary embodiment of the present invention generally comprises a core pack  110 , a case  120  on which the core pack  110  is seated, an adhesive  130  for gluing the core pack  110  to the case  120 , and a cover  140  for covering the upper portion of the case  120 .  
         [0032]     The core pack  110  includes an electrode assembly  114  that is formed by winding or laminating a positive electrode plate  111 , a separator  112 , and a negative electrode plate  113 . It also comprises a sheath member  115  for sealing the electrode assembly  114  while it is impregnated with an electrolyte (not shown), and a protective circuit module  117  that is positioned on the exterior of the sheath member  115  and is coupled to the electrode assembly  114 . The electrode assembly  114  and the protective circuit module  117  are coupled to each other by electrode tabs  118 . The protective circuit module  117  includes lead wires  119  that extend to the exterior of the case  120  that may be coupled to external devices.  
         [0033]     Although the edge  116  of the sheath member  115  is shown to bend upward and the protective circuit module  117  is shown to lie down in  FIG. 1B , the present invention is not limited to such a configuration of the core pack  110 . For example, the shape of or the type of bend at the edge  116  of the sheath member  115  of the core pack  110  may be modified in various ways as can the shape or position of the protective circuit module  117 . In addition, although the core pack  110  is shown to be glued to the case  120  while the protective circuit module  117  is positioned on the upper portion of the core pack  110  in  FIG. 1C , the method of gluing is not limited in the present invention. For example, the core pack  110  may be glued to the case  120  upside down, in contrast to the position shown in the  FIG. 1B . The present invention can use any manufactured core pack  110  and all kinds of sheath members  115 .  
         [0034]     For example, the sheath member  115  may be a flexible pouch that has a metallic layer  115   a , a first insulating layer  115   b  that is formed on a surface of the metallic layer  115   a , and a second insulating layer  115   c  that is formed on the other surface thereof. The metallic layer  115   a  may be made of any material including, but not limited to steel, stainless steel, aluminum, and an equivalent thereof. The first insulating layer  115   b  may be made of any material such as nylon, polyethylene terephthalate (PET), and an equivalent thereof. The second insulating layer  115   c  may be made of any material including, but not limited to cast polypropylene (CPP) and an equivalent thereof. The first and second insulating layers  115   b  and  115   c  become the external and internal surfaces of the sheath member  115 , respectively.  
         [0035]     The case  120  includes a bottom surface  121  that has the shape of a substantially rectangular plate and lateral walls  123  and  124  that extend up to a predetermined height from the four sides of the bottom surface  121 . The lateral walls  123  and  124  include a longitudinal lateral wall  123  and a traverse lateral wall  124 . The case  120  may be made of a conventional plastic resin or an equivalent thereof, but is not limited herein.  
         [0036]     The case  120  has at least one trench  122  that is formed on the bottom surface  121  to which the core pack  110  is glued with the adhesive  130 . The trench  122  may be formed with a predetermined spacing along the longitudinal direction of the bottom surface  121 . Particularly, the trench  122  may be formed parallel to the longitudinal lateral wall  123 . The depth of the trench  122  may correspond to 10-90% of the thickness of the case  120 , specifically the thickness of the bottom surface  121 .  
         [0037]     The traverse lateral wall  124  has a through-hole  125  that is formed thereon so that the lead wire  119  can be drawn to the exterior from the core pack  110 .  
         [0038]     The adhesive  130  is used to firmly glue the core pack  110  to the bottom surface  121  of the case  120 . Specifically, the adhesive  130  directly fastens the surface of the sheath member  115  of the core pack  110  to the bottom surface  121 , thereby preventing the core pack  110  from vibrating or escaping from inside the case  120 . The adhesive  130  may be a double-faced adhesive tape that has both surfaces coated with any sticky substance including, but not limited to non-woven fabric, acrylic, foam, and film or an equivalent thereof. For example, a conventional epoxy-based substance may be used for the adhesive  130 .  
         [0039]     The adhesive  130  is preferably made of material that has an adhesion force that decreases, and which dissolves when it is contacted with a solution such as xylene, toluene, methyl ethyl ketone, or an equivalent thereof. This property of the adhesive  130  allows the solution to easily separate the core pack  110  from the case  120 .  
         [0040]     Although the overall area of the adhesive  130  is shown to be smaller than the area of the core pack  110 , the present invention is not limited thereto. For example, the area of the adhesive  130  may be larger than that of the core pack  110  or equal to that of the bottom surface  121  of the case  120 .  
         [0041]     The cover  140  has the shape of a substantially rectangular plate and is fastened to the lateral walls  123  and  124  of the case  120  by an adhesive  141 . The sealing of the core pack  110  by the case  120  and the cover  140  in this manner protects the core pack  110  from the  5  external environment and allows the case  120  to be mounted on external devices.  
         [0042]      FIG. 2A  is a perspective view of a rechargeable battery pack according to another exemplary embodiment of the present invention.  FIG. 2B  is an exploded view of the rechargeable battery pack shown in  FIG. 2A .  
         [0043]     As shown in  FIG. 2A  and  FIG. 2B , a rechargeable battery pack  200  according to another exemplary embodiment of the present invention generally comprises a core pack  210 , a case  120  on which the core pack  210  is seated, an adhesive  130  for gluing the core pack  210  to the case  120 , and a cover  140  for covering the upper portion of the case  120 .  
         [0044]     The configuration of the case  120 , the adhesive  130 , and the cover  140  is similar to that mentioned above and the differences will mainly be described herein.  
         [0045]     As shown in the drawings, a sheath member  215 , which constitutes the exterior of the core pack  210  of the rechargeable battery pack  200  according to the present invention, may be a metallic can. The metallic can may be made of steel, stainless steel, aluminum, or an equivalent thereof, but is not limited herein. When the sheath member  215  is made of a metallic can, a protective circuit module  217  may be glued and fixed to a lateral surface of the sheath member  215  by a resin  219 . The protective circuit module  217  is provided with terminals  218 .  
         [0046]     The case  120  has a number of through-holes  125  that are formed on a surface  124  of the case  120  at locations that correspond to the terminals  218  that are formed on the protective circuit module  217 . The terminals  218  are exposed to the exterior of the case  120  via the through-holes  125 .  
         [0047]      FIG. 3A  is a sectional view taken along line  1 - 1  of  FIG. 1A .  FIG. 3B  is a sectional view that magnifies area  2  of  FIG. 3A .  FIG. 3C  is a top view that shows a case of a rechargeable battery pack according to an exemplary embodiment of the present invention.  
         [0048]     As shown in  FIG. 3A ,  FIG. 3B , and  FIG. 3C , the case  120  has a number of trenches  122  that are formed on the bottom surface  121  of the case  120  along the longitudinal lateral wall  123 . The trenches  122  act as passages through which a xylene, toluene, methyl ethyl ketone, or similar solution can pass in order to decrease the adhesion force of the adhesive  130 , if the adhesion is poor. Therefore, the more trenches there are, the easier it is to correct a poor adhesion.  
         [0049]     However, the trenches  122  reduce the adhesion area of the adhesive  130  and may degrade the adhesion force themselves. Accordingly, the number of trenches  122  must be carefully determined in consideration of such conditions. Although the sectional shape of the trenches  122  that are formed on the bottom surface  121  is shown to be a rectangle, this does not limit the shape of the trenches  122 . For example, the trenches  122  may have a semi-circular, inverted triangle, or polygonal cross-sections.  
         [0050]      FIG. 4  is a top view of a rechargeable battery pack according to another exemplary embodiment of the present invention.  
         [0051]     As shown in  FIG. 4 , the trenches  222  may be formed on the bottom surface  221  of the case  220  with a predetermined spacing while crossing one another along both diagonal directions, i.e., in a substantially “X”-shaped configuration. Such a configuration of the trenches  222  enables the solution to reach every region of the adhesive faster and more uniformly when separating the core pack from the case.  
         [0052]      FIG. 5  is a top view that shows a rechargeable battery pack according to another exemplary embodiment of the present invention.  
         [0053]     As shown in  FIG. 5 , the trenches  322  may be formed on the bottom surface  321  of the case  320  with a predetermined spacing while crossing one another along the longitudinal and traverse directions of the bottom surface  321  (i.e., along the longitudinal lateral wall  323  and the traverse lateral wall  324  thereof) in a substantially “+”-shaped configuration. Such a configuration of the trenches  322  enables the solution to reach every region of the adhesive faster and more uniformly when separating the core pack from the case.  
         [0054]      FIG. 6A  shows a method for separating a core pack from a case according to the present invention, wherein a rechargeable battery pack is dipped into a solution.  FIG. 6B  shows a sectional view taken along line  3 - 3  of  FIG. 6A .  
         [0055]     After a core pack  110  is glued to a case  120  with an adhesive  130  interposed between them, a test is generally performed to verify that the core pack  110  has been firmly glued to the case  120  in the correct position. If the test results confirm that the core pack  110  is out of the correct position or if it vibrates inside the case  120 , the core pack  110  is separated from the case  120  and the gluing process is repeated.  
         [0056]     According to the present invention, the core pack  110  and the case  120  are dipped into a solution  150  for a period of time to separate the core pack  110  and the case  120 , instead of forcibly removing the core pack  110  from the case  120 .  
         [0057]     The core pack  110  and the case  120  are dipped into a solution  150  comprising xylene, toluene, methyl ethyl ketone, or an equivalent thereof, for example, for a period of time so that the adhesion force of the adhesive  130  decreases or the adhesive  130  dissolves. Any material may be used in the solution  150  as long as it does not react with the core pack  110  and the case  120 .  
         [0058]     Furthermore, the bottom surface  121  of the case  120 , to which the adhesive  130  adheres, has at least one trench  122  that is formed along the longitudinal direction of the case  120 . It also has at least one trench  122  that is formed while crossing another trench  122  along the diagonal direction of the case  120 , or at least one trench  122  that is formed on the case  120  while crossing another trench  122  along the longitudinal and traverse directions thereof, so that the solution  150  can reach every region of the adhesive  130  faster and more uniformly.  
         [0059]     The depth of the trench  122  corresponds to 10-90% of the thickness of the case  120 . The adhesive  130  may be a double-faced adhesive tape that has both surfaces coated with any sticky substance including, but not limited to non-woven fabric, acrylic, foam, and film. The features of the trench  122  of the case  120  and the adhesive  130  have been described with reference to the second battery pack  100  and repeated descriptions thereof will be omitted.  
         [0060]     The protective circuit module  117  must face upward when dipping the core pack  110  and the case  120  into the solution  150  to prevent the protective circuit module  117 , which is fastened on the core pack  110 , from being contaminated by the solution  150 .  
         [0061]     After the dipping, the adhesion force of the adhesive  130  decreases or the adhesive  130  dissolves in the solution  150 . This allows the core pack  110  to easily be separated from the case  120 . The adhesive  130  can also be easily peeled off from the case  120  and the core pack  110 .  
         [0062]     In addition, any damage to the core pack  110 , specifically bulges, deformation, or fracture of the surface of the sheath member  115  can be avoided by reducing the adhesion force of the adhesive  130  or by the dissolving the adhesive  130  itself. This makes it possible to reglue the core pack  110  to the case  120  conveniently without any decrease in production yield of the battery pack  100 .  
         [0063]     It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.