Abstract:
The electric terminal includes a press surface, which is formed as a flat surface extending from the outer circumferential section towards the inside, on the edge of the case in the direction in which the through hole extends. The electric terminal is inserted into the through hole with the insulating member therebetween, and the press surface of the electric terminal is pressed. As a consequence, a portion of the outer circumferential section of the electric terminal expands towards the inner circumferential surface side of the through hole, thereby forming an expanded portion. The electric terminal is secured to the through hole by means of the surface pressure applied by the expanded section. As a result, it is possible to provide a battery which exerts excellent sealing properties at the position in which the case and the electric terminal are secured.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a battery, especially to the battery including an electric terminal fixed to a case with penetrating therethrough and projecting therefrom, in which the sealing property at the fixed portion is improved. 
       BACKGROUND ART 
       [0002]    The case as a housing of the battery includes a box and a lid. The box contains an electrode body as a power generating element and has an opening to form a closed-end shape. The plate lid has a shape in accordance with the opening of the box to cover it. 
         [0003]    The lid has a pair of through holes from which electric terminals are projected outward. The terminals work as the positive and negative electrode terminal for transmitting the electric power from the element. 
         [0004]    The case is provided with a safety unit such as a relief valve penetrating therethrough in the thickness direction. For example, the relief valve works in the case that the defect such as a short circuit results in generation of large volume of gas, communicating the inside of the battery with the outside to prevent the internal pressure from increasing. 
         [0005]    When the battery is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery, the contamination of water into the battery has an influence on the battery performance, so that the sealing property has to be secured. Furthermore, considering when the inner pressure raises caused by the inside defect, it is worth to seal the other portions to operate the safety unit securely. 
         [0006]    Regarding the case of the battery, the box and lid are firmly fixed by welding or the like, so that in the fixed portion of the terminal into the lid, it is required to keep the fitting property of the terminal not to slip out from the lid, the sealing property for preventing from leaking the electrolytes contained in the case and gases generated in the battery, and the insulating property between the terminal and the case. 
         [0007]    In the battery manufacturing process, particularly when fitting the terminal into the through hole formed in the lid, it is important to secure the sealing property of the fixed portion. 
         [0008]    JP 2005-302625 A discloses a battery having an electric terminal projecting from a lid of the battery, in which an insulating member is arranged between the lid and terminal, and the lid is provided with a flanged portion standing out around the insulating member, enabled to keep the sealing property between the lid and the terminal by pressing the flanged portion from the direction parallel to the lid, that is perpendicular to the thickness direction of the lid. 
         [0009]    Unfortunately, using the battery, a temperature cycle including heating and cooling is repeated, whereby the pressed portion is loosened to return the former shape and the sealing property is degraded. 
         [0010]    [Patent Literature 1] JP 2005-302625 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0011]    The objective of the present invention is to provide an unexpected battery including a case and an electric terminal fixed to the case with projecting therefrom, provided with high sealing property at the fixed portion between the case and terminal. 
       Technical Solution 
       [0012]    The first aspect of the invention is a method of manufacturing a battery, which includes a case provided with a through hole; an electric terminal fixed to the through hole with projecting outward from the case, the electric terminal including a press surface formed as a flat surface at one end thereof; and an insulating member interposed between the case and the electric terminal. In the embodiment of the method as the first aspect, the electric terminal surrounded by the insulating member is inserted into the through hole and the press surface of the electric terminal is pressed to expand the outer portion of the electric terminal toward the inside of the through hole, whereby the electric terminal is fixed to the through hole. 
         [0013]    Advantageously, the case is made of iron. 
         [0014]    In the preferable embodiment, a flanged portion is formed around the through hole, standing out from the case. 
         [0015]    The second aspect of the present invention is a battery, which includes a case provided with a through hole; an electric terminal fixed to the through hole with projecting outward from the case, the electric terminal comprising a press surface formed as a flat surface at one end thereof; an insulating member interposed between the case and the terminal, and with the terminal and the insulating member inserted in the through hole, the press surface of the electric terminal is pressed to expand the outer portion of the electric terminal toward the inside of the through hole, whereby the electric terminal is fixed to the through hole. 
         [0016]    Advantageously, the case is made of iron. 
         [0017]    In the preferable embodiment, the case includes a flanged portion around the through hole, standing out from the case. 
       Advantageous Effects of Invention 
       [0018]    According to the present invention, the battery is obtained that includes a case and an electric terminal fixed to the case with projecting therefrom, provided with high sealing property at the fixed portion between the case and terminal. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  depicts a battery according to the invention. 
           [0020]      FIG. 2  depicts a lid of a case provided with through holes. 
           [0021]      FIG. 3  illustrates an electric terminal. 
           [0022]      FIG. 4  is an enlarged section view illustrating a fixing portion of the case and the electric terminal. 
           [0023]      FIG. 5  shows a pressing method for fixing the electric terminal to the lid of the case, (a) illustrates the position relationship between those members, and (b) illustrates the state after pressing. 
           [0024]      FIG. 6  depicts the alternative embodiment of the lid of the case. 
           [0025]      FIG. 7  depicts the other embodiment of the lid of the case. 
           [0026]      FIG. 8  shows the alternative embodiment of the pressing method. 
           [0027]      FIG. 9  illustrates a battery module as the second embodiment of the battery. 
           [0028]      FIG. 10  illustrates a battery pack as the third embodiment of the battery. 
       
    
    
     REFERENCE SIGNS LIST 
       [0029]      10 : battery,  30 : case,  32 : lid,  33 : through hole,  40 : electric terminal,  43 : press surface,  44 : expanded portion,  50 : insulating member 
       DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0030]    Referring to  FIG. 1 , the structure of a battery  10  as a first embodiment of the present invention is explained below. 
         [0031]    The battery  10  is a single cell composed as a rechargeable secondary battery such as a lithium ion secondary battery, nickel-metal hydride battery or the like. 
         [0032]    As shown in  FIG. 1 , the battery  10  includes a power generating element  20  contained in a case  30 . The case  30  is penetrated by two electric terminals  40  projecting outward. 
         [0033]    The element  20  is made of an electrode body with electrolyte impregnation, which is formed by laminating or winding a positive electrode, a negative electrode and a separator. When charging or discharging the battery  10 , a chemical reaction is occurred in the element  20  (in detail, the ion moves between the positive and negative electrodes through the electrolytes), and thus the battery  10  works as the rechargeable secondary battery. 
         [0034]    The case  30  includes a box  31  and a lid  32 , and is made of iron (more specifically, nickel coated iron). The box  31  has a closed-end shape and an opening at one side, and contains the element  20 . The lid  32  has a shape corresponding to the opening of the box  31 , which covers the opening of the box  31  and is fixed to the box  31 . 
         [0035]    It should be noted that the materials of the box  31  and the lid  32  composing of the case  30  are not limited to the iron. In the embodiment, employing iron as the materials of the box  31  and the lid  32  from the viewpoint of strength, the materials such as aluminum which is used in the common batteries may be employed. Though, the metal having the strength (e.g. not less than 100 MPa) not less than that of iron is preferable. 
         [0036]    The terminals  40  are configured as a positive terminal or a negative terminal, each of which is fitted into the case  30  projecting from the outer periphery of the case  30 . For instance, the positive terminal  40  is made of aluminum and the negative terminal  40  is made of copper. 
         [0037]    The terminals  40  are electrically connected to the positive electrode or negative electrode of the element  20  via suitable wires such as lead terminals, and the electrodes  40  transmit the electric power between the inside and outside of the battery  10 . The terminals  40  are electric paths to the outside. The terminal  40  has a thread portion formed at the periphery, configured by thread rolling. 
         [0038]    Referring to  FIGS. 2 to 4 , the fixing embodiment among the case  30  and the terminals  40  is explained in detail. 
         [0039]    The terminals  40  are fixed to the lid  32  of the case  30  interposing insulating members  50  therebetween, which secure the insulating property between the terminals  40  and the case  30 . When fixing the terminals  40 , parts of the terminals  40  are pressed and the terminals  40  are compressed outward to fit the lid  32  and the insulating members  50  firmly. Thus, the sealing property between the lid  32  and the terminals  40  is secured. 
         [0040]    As shown in  FIG. 2 , the lid  32  has a pair of through holes  33  through which the terminals  40  pass. 
         [0041]    The holes  33  are drilled at predetermined diameters and penetrate the lid  32  in the thickness direction (in the vertical direction shown in drawings). 
         [0042]    The terminal  40  is round terminals, and has a projecting portion  41  and a fixing portion  42 . 
         [0043]    The projecting portion  41  is a columnar portion of the terminal  40  (formed at the outer side end of the battery  10 , that is the upper end in the drawings), which projects outward from the case  30 . The projecting portion  41  is used to connect with the external equipment such as the power resource, the device using the electric power of the battery  10  and the other batteries. The connecting terminal of the external equipment is connected and fixed to the projecting portion  41 . Because the projecting portion  41  works as the connector with the external devices, it has the thread portion at a part of the periphery or at the whole periphery. 
         [0044]    The fixing portion  42  has a columnar shape formed continuously to the projecting portion  41  and projects toward the axial direction of the projecting portion  41 . The outer diameter of the fixing portion  42  is larger than that of the projecting portion  41 . 
         [0045]    The outer diameter of the fixing portion  42  is set in accordance with the inner diameter of the insulating member  50 . With the fixing portion  42  inserted into the insulating member  50 , the electrode terminal  40  is fixed to the through hole  33  of the lid  32  (see  FIG. 4 ). 
         [0046]    The fixing portion  42  is formed at the other end of the terminal  40  (the end disposed at the inner side of the battery  10  and the lower end in the drawings). The fixing portion is fixed to the lid  32  and connected to the lead terminal of the power generating element  20 . The axial length of the fixing portion  42  is larger than the thickness of the lid  32  and the axial length of the insulating member  50 . 
         [0047]    At the one end of the terminal  40  (the end inside of the battery  10 , or the lower end in the drawings), or the connection portion between the projecting portion  41  and the fixing portion  42  where the diameter of the terminal changes, there is a press surface  43  having the desired width. The press surface  43  is a flat surface formed at the upper end of the fixing portion  42  and formed inward from the outside of the terminal  40 . The press surface  43  is pressed with a pressing tool  60 . The width of the press surface  43  is set such that the pressing area by the pressing tool  60  is sufficiently obtained. 
         [0048]    The press surface  43  of the terminal  40  has the deformation area deformed during the pressing, and therefore the deformation area is not used for the electrical connection with the external equipment. If the terminal  40  is large, the width of the press surface  43  may be large, so that the non-pressed portion of the press surface  43  may be used as the seat for the nut when connecting with the external equipment. 
         [0049]    As mentioned above, the terminal  40  has a stepped shape having the press surface  43  formed by the projecting portion  41  and the fixing portion  42 . When fixing the terminal  40  to the through hole  33  of the lid  32 , the outer side of the press surface  43  is pressed from outside of the battery  10  and thus the fixing portion  42  is plastic deformed and expanded outward (toward the insulating member  50 ), thereby fixing the terminal to the through hole. 
         [0050]    As depicted in  FIG. 4 , between the through hole  33  of the lid  32  and the fixing portion  42  of the terminal  40 , the insulating member  50  for insulating the case  30  with the terminal  40  is interposed. 
         [0051]    The insulating member  50  is an insulator having the shape corresponding to the fixing portion  42 , cylinder shape in the embodiment. The insulating member  50  wraps the fixing portion  42 . 
         [0052]    The axial length of the insulating member  50  is not shorter than that of the fixing portion  42 . That is, the axial length of the insulating member  50  is set such that there exist the enough length to insulate the outside of the terminal  40  (particularly the fixing portion  42 ) with the inside of the lid  32  when the terminal  40  is fixed to the lid  32 . 
         [0053]    The insulating member  50  is preferably made of a material with high temperature creek characteristics, or with long-term creep resistance against the temperature cycle of the battery  10 , for example, PEEK (poly (etheretherketone)). 
         [0054]    The insulating member  50  also acts as the sealing member for securing the sealing property in the battery  10 . 
         [0055]    As shown in  FIG. 4 , the outer portion of the press surface  43  of the terminal  40  is press-fitted all over the periphery, or the material plastically moves in response to the pressing, from the outside of the battery  10  (upper side of the drawings). 
         [0056]    Thus, an expanded portion  44  is formed such that the outer portion of the fixing portion  42  expands outward (more specifically, from the lower portion of the press surface  43  to be pressed). The expanded portion  44  is surrounded by the insulating member  50  which is made of softer material than the terminal  40 , so that the expanded portion  44  expands toward the insulating member  50  (toward the inside of the through hole  33 ). 
         [0057]    The expanded portion  44  expanded outside presses the insulating member  50 , and the pressure is applied to the insulating member  50  as contact surface pressure. The portion in the insulating member  50  to which the contact surface pressure applied by the expanded portion  44  is elastically deformed outward, and the force in accordance with the elastic deformation is applied to the inside of the through hole  33  as contact surface pressure. 
         [0058]    Thus, the press surface  43  of the terminal  40  is press-fitted from the upper side, forming the expanded portion  44  expanded outward, thereby the contact surface pressure is transmitted to the inside of the through hole  33  of the lid  32  via the insulating member  50 . By the pressure, the lid  32  is pressed and the terminal  40  is fixed to the lid  32  of the case  30 . 
         [0059]    Due to the plastic deformation of the expanded portion  44  and the elastic deformation of the insulating member  50 , there is no gap among the inside of the hole  33 , the insulating member  50  and the fixing portion  42 , occurring high bonding force therebetween. The sealing property between the lid  32  of the case  30  and terminal  40  is secured, thereby keeping the sealing property of the battery  10 . The expanded portion  44  is press-fitted in the direction perpendicular to the expansion direction, so that the press-fitted portion does not return (loosen) according to the high contact surface pressure and friction force acting on the expanded portion, namely, the expanded portion is not easy to loosen. 
         [0060]    Referring to  FIG. 5 , the pressing embodiment where the terminal  40  is fixed to the lid  32 . 
         [0061]    As depicted in  FIG. 5(   a ), the insulating member  50  is arranged at the outside of the fixing portion  42  of the terminal  40 , and the terminal  40  and the insulating member  50  are inserted into the through hole  33 . 
         [0062]    The terminal  40  and the lid  32  are arranged such that the expanded portion  44  to be formed after pressing faces the inside of the hole  33 . 
         [0063]    As depicted in  FIG. 5(   b ), using the pressing tool  60 , the outer area of the press surface  43  of the terminal  40  is pressed by the predetermined amount from the outside of the battery  10 , thereby forming the expanded portion  44  below the press surface  43  (inner side of the case  30 ). The expanded portion  44  expands toward the radially outwardly and therefore the surface pressure is occurred at the inside of the through hole  33  and insulating member  50 . The surface pressure makes the terminal  40  and the insulating member  50  held and fixed to the lid  32 . 
         [0064]    The pressing tool  60  has a cylinder shape in which the part of the terminal  40  passes, and has a pressing blade  61  for pressing the press surface  43  provided at the end thereof. The pressing tool  60  is movable to approach/separate from the terminal  40  with a proper actuator. 
         [0065]    During the pressing using the pressing tool  60 , the proper jig is used to hold the lid  32 , the terminal  40  and the insulating member  50 . 
         [0066]    The battery  10  includes the terminal  40  formed in stepped shape with the press surface  43  having the predetermined width, in which the press surface  43  is pressed from the outside and the area beneath the press surface  43  (pressed area) plastically moves outward, thereby forming the expanded portion  44 . Thus, the sufficient surface pressure acts on the insulating member  50  surrounding the terminal  40  and the inside of the hole  33  disposed at the outside of the insulating member. Therefore, the terminal  40  and the insulating member  50  are solidly fixed in the hole  33 , securing the bonding property therebetween. With respect to the battery  10  in which the terminal  40  projecting outward from the case  30  is fixed to the hole  33  of lid  32 , the sealing property at the hole  33  as the fixing portion is improved. 
         [0067]    Moreover, the expanded portion  44  is expanded outward, that is to expand the insulating member  50  and the lid  32  outwardly, thereby preventing the wrinkles at the insulating member  50  and the lid  32 , and therefore the sealing property is maintained. 
         [0068]    The lid  32  is made of iron that is high strength material, so that the high rigidity along the elongation direction of the lid  32  (the left-right direction in the drawings) is obtained. 
         [0069]    Therefore, if the inner pressure rises, the battery  10  has resistance against the pressure acted on the lid  32  from the terminal  40  (around the through hole  33 ), so that the lifetime of the battery is improved. 
         [0070]    In the embodiment, the through hole  33  is true circle, but the shape of the hole is not limited to that. For instance, the hole  33  may be shaped as an ellipse, rectangular, polygon or the like, in which the distance from the center of the hole to the inside is not even. In such structure, the expansion shape (viewed from the pressing direction) of the expanded portion  44  may be controlled to form the shape corresponding to the hole shape. In this case, the expanded portion  44  may be formed in the non-circular shape, thereby providing the terminal  40  with torque resistance and avoiding the defects caused by the rotation of the terminal  40  occurred during the connection with the outer equipment. 
         [0071]    As the shape of the hole  33 , the terminal  40  having stepped shape by the press surface  43  may be formed in non-circular shape, for example, forming the projecting portion  41  in circular shape and the fixing portion  42  in non-circular shape. 
         [0072]    As depicted in  FIG. 6 , in the preferable alternative embodiment of the lid  32  of the case  30 , the through hole  33  is formed with a flanged portion  34 , thereby improving the rigidity around hole  33  of the lid  32 . 
         [0073]    The flanged portion  34  is formed at the edge of the hole  33  and stands out from the case  30  from inside to outside thereof (in the vertical direction shown in drawings). The flanged portion  34  is projected from the outer face of the lid  32 , and defines the hole  33  at the inner wall thereof. 
         [0074]    The part of the lid  32  (around the hole  33 ) is plastically deformed to form the flanged portion  34 , which is formed by burring processing, deep drawing, damming, or the like. It should be noted that the lower end of the inside of the flanged portion  34  facing the hole  33  is formed in right angle, shown in  FIG. 6 , by die forming or the like. 
         [0075]    Due to the flanged portion  34  formed around the hole  33  of the lid  32 , the portion of the lid  32  around the terminal  40  may be increased, so that the holding force of the hole  33  for the terminal  40  is increased. The sealing property of the battery  10  is maintained when the vibration of the like occurs while using the battery  10 , and therefore, the lifetime of the battery  10  can be improved. 
         [0076]    Furthermore, as shown in  FIG. 7 , the flanged portion  34  projecting from the top of the lid  32  may be surrounded by a reinforcing ring  35 . 
         [0077]    The reinforcing ring  35  is a ring member formed in a shape corresponding to the flanged portion  34 , made of metal having not less strength than the material of the lid  32 . Arranging the reinforcing ring  35  at the periphery of the flanged portion  34 , the thickness in the expanding direction of the expanded portion  44  at the side of lid  32  is increased and the flanged portion  34  is prevented from deforming outward, whereby the terminal  40  is held rigidly. As described above, the sealing property at the through hole  33  may be improved. 
         [0078]    In the embodiment, the pressing direction to the terminal  40  is the direction from outside to inside of the battery  10 , but, as shown in  FIG. 8 , the pressing may be operated from inside of the battery  10 . 
         [0079]    In this case, the projecting portion  41  of the terminal  40  may be continued to a seating surface  45  for connection to the external equipment, and thus the conductive area between the battery  10  and the external terminal is enlarged, thereby improving the conductive efficiency. 
       Second Embodiment 
       [0080]    Referring to  FIG. 9 , a battery module  110  as a second embodiment of the invention will be described. The battery module  110  is an assembled battery composed of multiple batteries connected in series or in parallel. 
         [0081]    As shown in  FIG. 9 , the battery module  110  includes multiple battery cells  120  and a pair of electric terminals  140 . 
         [0082]    The battery cells  120  are configured as a lithium ion secondary battery, nickel-metal hydride battery or the like, arranged contacting adjacently to each other and connected in series or in parallel. Each of the battery cells  120  is electrically connected in the case thereof, and the battery cells  120  that are disposed at both ends in the arrangement direction have the positive terminal  140  and the negative terminal  140  projecting outward. 
         [0083]    The electric power is transmitted between inside and outside of the battery module  110  (or the battery cells  120 ) through the terminals  140 . 
         [0084]    The terminals  140  have the same structure as the electric terminals  40  in the first embodiment, including the press surfaces. Each terminal  140  is fixed to the through hole  133  formed at the case of the battery cell  120 . The fixing method of the terminal  140  to the hole  133  may be performed as that of the first embodiment. 
         [0085]    As the result, the battery module  110  obtains the same effects as the battery  10 , thereby improving the sealing property at the holes  133  through which the electric terminals  140  pass. 
       Third Embodiment 
       [0086]    Referring to  FIG. 10 , a battery pack  210  as the third embodiment of the invention will be described. The battery pack  210  is an assembled battery housing multiple batteries connected in series or in parallel in a case. 
         [0087]    As shown in  FIG. 10 , the battery  210  includes multiple battery cells  220 , a case  230  housing the battery cells  220  and a pair of electric terminals  240 . 
         [0088]    The battery cells  220  configured as a lithium ion secondary battery, nickel-metal hydride battery or the like. Each of the battery cells  220  is electrically connected in the case  230 . 
         [0089]    The case  230  contains the battery cells  220 , in which the cooling medium such as oil is filled. The terminals  240  are projected outward from the one side of the case  230 . 
         [0090]    The terminals  240  are electrically connected to the battery cells  220  via lead terminals. 
         [0091]    The electric power is transmitted between inside and outside of the battery pack  210  (or the battery cells  220 ) through the terminals  240 . 
         [0092]    The terminals  240  have the same structure as the electric terminals  40  in the first embodiment, including the press surfaces. Each terminal  240  is fixed to the through hole  233  formed at the case  230 . The fixing method of the terminal  240  to the hole  233  may be performed as that of the first embodiment. 
         [0093]    As the result, the battery pack  210  obtains the same effects as the battery  10 , thereby improving the sealing property at the holes  233  through which the electric terminals  240  pass. 
         [0094]    As described in the first to third embodiments, in which the method for fixing the electric terminal to the case is employed, the terminals  40 ,  140  and  240  are pressed from the outside to inside of the batteries  10 ,  110  and  210 , and plastically deformed outward (toward the inside of the through hole of the case), whereby the terminals are rigidly fixed to the holes, however, the fixing method is not limited to the battery. For instance, it is applicable to the case where the electrical terminals for taking out the electric power from the metal case are penetrated to the case, securing the sealing structure of the case and fixing the terminals rigidly. 
       INDUSTRIAL APPLICABILITY 
       [0095]    The present invention is applicable to a battery including a case and an electric terminal projecting from the case, particularly to the technique of securing sealing property in the through hole formed in the case through which the terminal penetrates.