Abstract:
A cell block including a metal case including a plurality of pipe-shaped members and a plurality of single cells housed in each of the pipe-shaped members. Each of the pipe-shaped members is joined at joining surfaces, and the pipe-shaped members are joined and integrated. A member for housing single cells is provided, and the housing member is molded with a high degree of accuracy and is capable of being manufactured at low cost and in a simple manner.

Description:
TECHNICAL FIELD 
     The present invention relates to a battery block and a method of manufacturing the same. 
     BACKGROUND ART 
     It is known that a plurality of unit cells are accommodated in one accommodation member to obtain a battery block, and this battery block is used as a high-capacity storage battery. As the accommodation member, an assembly in which cylindrical metallic pipes are spot-welded, an assembly in which a plurality of cases having an accommodation hole are integrally surface-joined, and the like are known (refer to PTL 1). 
     In addition to this, various related technologies are disclosed (for example, refer to PTLs 2 to 8). 
     For example, PTL 2 discloses a high-temperature storage battery in which a plurality of storage battery cells are disposed in a predetermined arrangement, and adjacent storage battery cells are partially joined to each other by an external case. PTL 3 also discloses the same invention as PTL 2. However, according to the invention disclosed in PTLs 2 and 3, the storage battery cell is joined to the external case only at several points, and thus it is difficult to suppress local temperature increase by diffusing heat. 
     In addition, PTL 4 discloses a sodium secondary battery module in which a container main body of an accommodation container assembly is disposed so as to be inserted between thin plates having a semicircular cross section in a lateral direction. However, a joining area between the container main body and the thin plates is small, and thus it is difficult to effectively diffuse heat. 
     PTL 5 discloses a method of manufacturing a brazing pipe that is used in a header of a heat exchanger, and a method of manufacturing a heat exchanger, but problems in common with the battery block are not mentioned. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: Japanese Patent Application Laid-Open No. 2-256174 
         PTL 2: Japanese Patent Application Laid-Open No. 60-119084 
         PTL 3: Japanese Patent Application Laid-Open No. 4-284370 
         PTL 4: Japanese Patent Application Laid-Open No. 2004-265743 
         PTL 5: Japanese Patent Application Laid-Open No. 2009-297722 
         PTL 6: U.S. Pat. No. 4,546,056 
         PTL 7: US Patent Application Laid-Open No. 2009-0255656 
         PTL 8: U.S. Pat. No. 5,763,116 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In a member that accommodates unit cells of a storage battery, high shaping accuracy is required in order to quickly make a temperature distribution of each of the unit cells uniform, or in order to suppress a local temperature increase by diffusing heat in a case where abnormal heat generation (that may occur due to short-circuit inside the unit cell) occurs in the unit cell. In addition, shaping accuracy of a portion in which the unit cell is accommodated is important. When the shaping accuracy of the portion in which the unit cell is accommodated is poor, in a case where a storage battery is installed at a location susceptible to vibration, the accommodated unit cell may vibrate. When the accommodate unit cell vibrates, the unit cell may not exhibit a sufficient cell function, deterioration of the unit cell is advanced, or a cell interconnection is cut. Accordingly, a performance of the storage battery may deteriorate. 
     In addition, in recent years, high capacity of the storage battery has been strongly requested. It is necessary to accommodate many unit cells in the accommodation member so as to realize high capacity of the storage battery. To accommodate relatively many unit cells for a unit volume, it is necessary to reduce an interval between unit cells. It is necessary for the accommodation member to be relatively thin so as to reduce the interval between the unit cells. When the accommodation member is made to be thin, there is a tendency for the shaping accuracy of the accommodation member to decrease. 
     Therefore, an object of the invention is to provide a member accommodating a plurality of unit cells, which has high shaping accuracy. 
     Solution to Problem 
     A first aspect of the invention relates to a battery block described below. 
     [1] A battery block, including: 
     a metallic case that includes a plurality of pipe-shaped members; and 
     a plurality of unit cells that are accommodated in the pipe-shaped members, respectively, 
     wherein the pipe-shaped members are joined at mating faces, respectively, and 
     the plurality of pipe-shaped members are joined to each other and are integrated with each other. 
     [2] The battery block according to [1], 
     wherein the joining of the pipe-shaped members at the mating faces and the joining between the pipe-shaped members are realized by brazed joints. 
     [3] The battery block according to [1] or [2], 
     wherein the pipe-shaped member is a member that is obtained by bending a metallic plate including a core material and a brazing material layer into a pipe shape, and performing brazing at the mating faces. 
     [4] The battery block according to [1], 
     wherein the pipe-shaped member is a member that is obtained by bending a metallic plate into a pipe shape, and performing bonding with an adhesive, metal welding, or diffusion joining at the mating faces. 
     [5] The battery block according to any one of [1] to [4], 
     wherein the pipe-shaped member is formed from aluminum, copper, brass, or stainless steel. 
     [6] The battery block according to any one of [1] to [5], 
     wherein the pipe-shaped member is a circular pipe or a polygonal pipe. 
     [7] The battery block according to any one of [1] to [6], 
     wherein the pipe-shaped member has a penetration slot or a notch portion. 
     [8] The battery block according to [1], 
     wherein a gap between the mating faces is 0.05 to 0.2 mm. 
     [9] The battery block according to [1], 
     wherein the pipe-shaped member has a protrusion at the mating faces, the protrusion protruding into a hollow of the pipe-shaped member. 
     A second aspect of the invention relates to a method of manufacturing a battery block, which is described below. 
     [10] A method of manufacturing a battery block, the method including: 
     a step of obtaining a plurality of pipe-shaped metallic plates having a brazing material layer on an outer circumferential surface by bending a metallic plate including a core material and the brazing material layer to constitute mating faces; 
     a step of obtaining an assembly of the pipe-shaped metallic plates by bringing the plurality of pipe-shaped metallic plates into contact with each other and fixing the plates to each other; and 
     a step of obtaining a battery case by heating the assembly of the pipe-shaped metallic plates, brazing the mating faces of each of the pipe-shaped metallic plates to form a pipe-shaped member, and brazing the pipe-shaped metallic plates with each other. 
     [11] A method of manufacturing a battery block, the method including: 
     a step of obtaining a plurality of pipe-shaped metallic plates by bending a metallic plate to constitute mating faces; 
     a step of obtaining an assembly of the pipe-shaped metallic plates by bringing the plurality of pipe-shaped metallic plates into contact with each other and fixing the plates to each other; 
     a step of disposing a brazing material on an outer circumferential surface of the assembly; and 
     a step of obtaining a battery case by heating the assembly on which the brazing material is disposed, brazing the mating faces of each of the pipe-shaped metallic plates to form a pipe-shaped member, and brazing the pipe-shaped metallic plates with each other. 
     [12] The method of manufacturing the battery block according to [10] or [11], further including: 
     a step of accommodating a unit cell in a hollow portion of the pipe-shaped member of the battery ease. 
     Advantageous Effects of Invention 
     According to the battery block of the invention, since shaping accuracy of a metallic case, which is an accommodation container of a unit cell, is high, a temperature distribution of the unit cell quickly becomes uniform, and in a case where abnormal heat generation occurs in the unit cell, a local temperature increase is suppressed by diffusing heat. In addition, since shaping accuracy of a portion in which the unit cell is accommodated is high, vibration of the accommodated unit cell is suppressed. Accordingly, a performance as a storage battery does not deteriorate. As a result, even in a case of a storage battery that is used under a circumstance that is susceptible to vibration, an effective battery block is provided. For example, the storage battery, which is used under a circumstance susceptible to vibration, is for a vehicle. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a perspective diagram of a battery block of the invention; 
         FIG. 1B  is an exploded perspective diagram of the battery block of the invention; 
         FIGS. 2A and 2B  are diagrams illustrating an example of a shape of a pipe-shaped member; 
         FIGS. 3A and 3B  are diagrams illustrating an arrangement state of the pipe-shaped member; 
         FIG. 4A  is a diagram illustrating mating faces of the pipe-shaped member; 
         FIG. 4B  is a diagram illustrating the mating faces of the pipe-shaped member; 
         FIGS. 5A, 5B, and 5C  are diagrams illustrating a method of obtaining a pipe-shaped member in which a brazing material is disposed on an outer circumferential surface thereof, and  FIG. 5D  is a diagram illustrating a protrusion that is formed by junction at the mating faces; 
         FIG. 6A  is a diagram illustrating a gap between mating faces of the pipe-shaped member; 
         FIG. 6B  is a diagram illustrating the gap between the mating faces of the pipe-shaped member; 
         FIG. 6C  is a diagram illustrating the gap between the mating faces of the pipe-shaped member; 
         FIG. 7A  is a diagram illustrating a pipe-shaped member having a penetration slot; 
         FIG. 7B  is a diagram illustrating a pipe-shaped member having a notch; 
         FIGS. 8A and 8B  are diagrams illustrating a position of mating faces in a plurality of pipe-shaped members constituting a metallic case; 
         FIG. 9A  is a diagram illustrating a state in which an assembly of the plurality of pipe-shaped members is temporarily fixed by a frame body; 
         FIG. 9B  is a diagram illustrating a state in which the assembly of the plurality of pipe-shaped members is temporarily fixed by the frame body; 
         FIGS. 10A, 10B, and 10C  are diagrams illustrating a metallic case including the plurality of pipe-shaped members and a metallic member inserted in a gap between the pipe-shaped members; 
         FIG. 11  is a diagram illustrating flowing of a coolant through the gap between the pipe-shaped members in the metallic case; 
         FIGS. 12A, 12B, 12C, and 12D  are diagrams illustrating an example of a manufacturing flow of the metallic case of the battery block of the invention; and 
         FIG. 13  is a diagram illustrating a state in which a plurality of unit cells are accommodated in the metallic case. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A battery block of the invention includes a metallic case and a plurality of unit cells. The metallic case includes a plurality of pipe-shaped members, and each of the unit cells is accommodated in a hollow portion of each of the pipe-shaped members. The unit cell that is included in the battery block has an electricity storage performance. Therefore, it is preferable that the battery block function as a high-capacity storage battery. 
     Battery Block 
     In  FIGS. 1A and 1B , summery of an example of the battery block of the invention is shown.  FIG. 1A  shows a perspective diagram of battery block  100  of the invention.  FIG. 1B  shows an exploded perspective diagram of battery block  100 . As shown in  FIG. 1B , battery block  100  includes electrode plate  10 , holder  20 , assembly  31  of pipe-shaped members  31   a ,  31   b , . . . ,  31   t , a plurality of unit cells  40  ( 40   a ,  40   b , . . . ,  40   t ), holder  50 , and electrode plate  60 . 
     Unit cells  40   a ,  40   b , . . . ,  40   t  are accommodated in corresponding pipe-shaped members  31   a ,  31   b , . . . ,  31   t , respectively. Unit cells  40  that are accommodated are supported by holders  20  and  50 . One electrode  41  of each of unit cells is connected to electrode plate  10  and the other electrode  42  is connected to electrode plate  60 . 
     As shown in  FIG. 1B , unit cells  40   a ,  40   b , . . . ,  40   t  are accommodated in corresponding pipe-shaped members  31   a ,  31   b , . . . ,  31   t , respectively. Assembly  31  including the plurality of pipe-shaped members constitutes a metallic case of the battery block of the invention. It is preferable that pipe-shaped members  31   a ,  31   b , . . . ,  31   t  be fixed in a state of being brought into contact with each other and be integrated with each other. 
     It is preferable that the plurality of pipe-shaped members  31   a ,  31   b , . . . ,  31   t , which constitute the metallic case, be joined to each other and be integrated to form an assembly. More specifically, respective side surfaces of the plurality of pipe-shaped members  31   a ,  31   b , . . . ,  31   t  are joined to each other to be integrated. Assembly  31  of the pipe-shaped members that is included in one battery case may be constructed by two or more pipe-shaped members, and the upper limit is not particularly limited. In addition, the metallic case may further include frame body  400  surrounding assembly  31  of the pipe-shaped members (refer to  FIG. 9A  to be described later). 
     Pipe-shaped member  31  may be, for example, circular pipe  31 - 1  as shown in  FIG. 2A , or polygonal pipe  31 - 2  such as a tetragon as shown in  FIG. 2B . The inside of each of pipe-shaped members  31   a ,  31   b , . . . ,  31   t  is constructed by a cavity along an axial direction of a pipe. In each of pipe-shaped members  31   a ,  31   b , . . . ,  31   t , each of unit cells  40   a ,  40   b , . . . ,  40   t  is accommodated. Commonly, each of unit cells  40   a ,  40   b , . . . ,  40   t  has a cylindrical shape. 
     It is preferable that the plurality of pipe-shaped members  31   a ,  31   b , . . . ,  31   t  be integrated in such a manner that these come into contact with each other. An arrangement aspect of pipe-shaped members  31   a ,  31   b , . . . ,  31   t  is not particularly limited. For example, in a case where respective pipe-shaped members  31   a ,  31   b , . . . ,  31   t  are circular pipes, as shown in  FIG. 3A , the circular pipes may be arranged in a close packing manner. In addition, as shown in  FIG. 3B , respective pipe-shaped members  31   a ,  31   b , . . . ,  31   u  may be squarely arranged. In  FIGS. 3A and 3B , mating faces  35  are not shown. 
     It is preferable that pipe-shaped member  31  be formed from a metal. It is preferable that a constituent metal of pipe-shaped member  31  be a metal having high heat conductivity. Specific examples include aluminum, copper, brass, stainless steel, an alloy thereof, and the like. Aluminum is preferable for realizing lightness of the pipe-shaped member. 
     It is preferable that the thickness of the plate constituting pipe-shaped member  31  be 0.2 to 0.8 mm, and for example, approximately 0.4 mm. The smaller the thickness is, the further the metallic case becomes light. Accordingly, this is preferable. However, when the thickness is too small, the strength that is necessary for the case may not be obtained. 
     A hollow size of pipe-shaped member  31  is set in accordance with the size of unit cell  40  that is accommodated therein. That is, it is preferable that a diameter of a hollow cross-section be slightly larger than a diameter of a cross-section of unit cell  40  that is accommodated in the hollow. This is because it is necessary to accommodate the unit cell in a hollow portion. It is preferable that a difference (clearance) between the diameter of the hollow cross-section of pipe-shaped member  31  and the diameter of the cross-section of unit cell  40  (including an insulating sheet in a case of covering the unit cell with the insulation sheet) that is accommodated therein be 0.01 to 0.38 mm. When the clearance is too large, the unit cell that is accommodated vibrates, and thus this is not preferable. When the clearance is too small, the unit cell may not be accommodated. 
     As shown in  FIGS. 2A and 2B , pipe-shaped member  31  has mating faces  35 , and is joined at the mating faces. “Mating faces  35 ” represents mating faces  35  to be joined when one sheet of metal flat plate  200 , for example, as shown in  FIG. 4A  is bent into a pipe shape. In addition, “Mating faces  35 ” represents mating faces  35  to be joined when two half-pipe-shaped metal plates  300 , for example, as shown in  FIG. 4B  are joined into a pipe shape. 
     As described above, pipe-shaped member  31  may be obtained by bending a metallic flat plate and joining the mating faces (refer to  FIG. 4A ), or by joining half-pipe-shaped members (refer to  FIG. 4B ). Examples of joining means at mating faces  35  include brazing, bonding with an adhesive, metal welding, diffusion joining, and the like, and among these, brazing is preferable. According to the brazing, the mating faces may be joined by the same process as a joining process (described later) between pipe members. 
     Relationship Between Joining Method and Protrusion 
     As shown in  FIGS. 2A and 2B , each of pipe-shaped members  31  ( 31 - 1  and  31 - 2 ) may have protrusion  38  that is formed on a hollow inner surface of the pipe at mating faces  35 . Although not particularly limited, it is preferable that protrusion  38  be a protrusion generated due to joining at mating faces  35 . Hereinafter, a relationship between the joining method and protrusion  38  will be described with reference to  FIGS. 5A to 5D . 
     1) Case of Joining by Brazing 
     Pipe-shaped member  31  may be obtained by disposing a brazing material on an outer circumferential surface of non-joined pipe-shaped member (pipe-shaped metallic plate)  30   a  having mating faces  35 , and heating the brazing material to braze pipe-shaped member  30   a . For example, non-joined pipe-shaped member  30   a  in which the brazing material is disposed on the outer circumferential surface thereof may be manufactured by the following methods a), b), or c). The “brazing material” represents an alloy having a melting point lower than that of a metal constituting a core material. 
     a) As shown in  FIG. 5A , metal plate  230  including core material  210  and brazing material layer  220  may be bent into a pipe shape. 
     b) As shown in  FIG. 5B , metal flat plate  200  may be bent into a pipe shape, and then brazing sheet (thin brazing material)  240  may be wound around the resultant pipe-shaped member. 
     c) As shown in  FIG. 5C , metal flat plate  200  may be bent into a pipe shape, and then brazing paste (brazing paste)  250  may be applied to the resultant pipe-shaped member. 
     In this manner, non-joined pipe-shaped member (pipe-shaped metallic plate)  30   a  in which the brazing material is disposed on the outer circumferential surface thereof is prepared. In addition, a method of manufacturing non-joined pipe-shaped member (pipe-shaped metallic plate)  30   a  is not particularly limited to the above-described method. 
     At mating faces  35  of pipe-shaped metallic plate  30   a  having mating faces  35 , it is preferable that ends of pipe-shaped metallic plate  30   a  in a lateral direction do not come into completely contact with each other, and a gap be provided between mating faces  35 . In addition, pipe-shaped metallic plate  30   a  in which the brazing material is disposed on the outer circumferential surface thereof is heated to braze the mating faces. The brazing is performed by heating the pipe to a temperature higher than the melting point of the brazing material. In the brazing process, it is preferable that the brazing material flow into the gap between the mating faces, and the brazing material further leak to a hollow inner to form a protrusion. In this manner, the joining at mating faces  35 , and formation of protrusion  38  that is formed from the remainder of the brazing material may be performed (refer to  FIG. 5D ). 
     As shown in  FIG. 6A , it is preferable that interval t 1  of the gap between mating faces  35  of pipe-shaped metallic plate  30   a  be 0.05 to 0.2 mm. This is because the brazing material easily intrudes into the gap with a capillary phenomenon. When the gap is too narrow, it is difficult for the brazing material to flow into the gap, and thus the protrusion may not be formed. On the other hand, when the gap is too broad, the capillary phenomenon does not occur, and thus the brazing may not performed. 
     In addition, a shape of the gap between mating faces  35  may be adjusted to allow the brazing material to easily flow into the gap so as to reliably form the protrusion. For example, as shown in  FIG. 6B , mating faces  35  may be formed to be inclined with respect to a main surface of pipe-shaped metallic plate  30   a . In this case, it is preferable that an interval t 2  of the gap of pipe-shaped metallic plate  30   a  be 0.05 to 0.2 mm. This is due to the same reason as  FIG. 6A . 
     In addition, as shown in  FIG. 6C , each of mating faces  35  may be formed in a multi-step. This is because when the shape of the gap between mating faces  35  is adjusted, the brazing material easily flows into the gap, and thus an appropriate protrusion is formed. In this case, it is preferable that interval t 3  of the gap be 0.2 mm or less. In addition, it is preferable interval t 4  of the gap be 0.05 to 0.2 mm. In addition, it is preferable that interval t 5  of the gap be 0.5 mm or less. 
     2) Case of Joining by Adhesive 
     Pipe-shaped member  31  may be obtained by applying an adhesive to mating faces  35  of pipe-shaped metallic plate  30   a  having mating faces  35  to bond mating faces  35  with each other. In this bonding, the applied adhesive leaks to the hollow inner surface to form a protrusion. That is, a protrusion formed from the remainder of the adhesive is formed. 
     3) Case of Joining by Welding 
     Pipe-shaped member  31  may be obtained by metal-welding mating faces  35  of pipe-shaped metallic plate  30   a  having mating faces  35 . Means for the metal welding is not particularly limited, and TIG welding, laser welding, or the like may be exemplified. In a ease of performing the metal welding, it is preferable to bring mating faces  35  of the metallic plate into close contact with each other. When mating faces  35 , which are brought into close contact with each other, are welded by metal melting, a protrusion called “welding protrusion” may be formed. When this welding protrusion is positively formed, a protrusion protruding into the hollow is formed. 
     4) Case of Joining by Diffusion Joining 
     Pipe-shaped member  31  may be obtained by diffusion-joining mating faces  35  of pipe-shaped metallic plate  30  having mating faces  35 . The diffusion joining is performed by pressing and heating metal plates that overlap each other at mating faces  35 . When the metal plates are pressed, a protrusion may be pressure-molded at the mating faces. 
     It is preferable that the height of protrusion  38  (refer to  FIGS. 2A and 2B ) at the mating faces of pipe-shaped member  31  be set in accordance with a difference (clearance) between the diameter of the hollow cross-section of pipe-shaped member  31  and the diameter of the cross-section of the unit cell (including an insulating sheet in a case of covering the unit cell with the insulation sheet) that is accommodated therein. The height may be set to be larger than the clearance. The height of protrusion  38  as a reference may be equal to or more than “the sum of the clearance and ⅕ of the thickness of the insulation sheet that covers the unit cell”, and may be equal to or less than “the sum of the clearance and ⅓ of the thickness of the insulation sheet that covers the unit cell.” Protrusion  38  suppresses vibration or rotation of the unit cell accommodated in the hollow portion of pipe-shaped member  31 . 
     As shown in  FIG. 7A , penetration slot  32  may be provided in a part of the side surface of pipe-shaped metallic plate  30   a . As shown in  FIG. 7B , notch  33  may be provided at each of both ends in a longitudinal direction. This is because an external member (a temperature sensor or the like) may be connected to the unit cell (not shown) through penetration slot  32  or notch  33 , the unit cell being accommodated in the inside. 
     As described above, the metallic case constituting the battery block includes the plurality of pipe-shaped members. The plurality of pipe-shaped members come into contact with each other and are integrated with each other. Specifically, the respective pipe-shaped members are joined to each other at a side surface of the respective pipe-shaped member and are integrated with each other. 
     The joining between the pipe-shaped members is performed by brazing, bonding with an adhesive, metal welding, or the like, but the joining is preferably performed by brazing. For example, a plurality of pipe-shaped metallic plates, in which a brazing material is disposed on an outer circumferential surface thereof, are brought into contact with each other and are temporarily fixed to form an assembly, and the resultant assembly is heated to join the pipe-shaped members (pipe-shaped metallic plates) to each other. 
     Each of the pipe-shaped members that are to be temporarily fixed to form the assembly may be a member after the joining at mating faces  35  or a member before the joining. In a case of temporarily fixing the plurality of pipe-shaped members (pipe-shaped metallic plates) having mating faces  35  before the joining to form the assembly, the joining at mating faces  35  and the joining between pipe-shaped metallic plates  30  that become pipe-shaped members  31  may be performed in the same process, and thus this case is preferable. 
     As shown in  FIG. 8A , mating faces  35  of pipe-shaped metallic plates  30  ( 30   a ,  30   b , . . . ,  30   e ) that become the plurality of pipe-shaped members may be regularly arranged in the same direction, or may be randomly disposed as shown in  FIG. 8B . In  FIG. 8A , mating faces  35  are disposed on an upper side in the drawing. When mating faces  35  are disposed in the same direction, for example, an effect in which the brazing material easily flows into the gap between mating faces  35  may be obtained. 
     When pipe-shaped metallic plates  30  ( 30   a ,  30   b , . . . ,  30   e ) are intended to be temporarily fixed, as shown in  FIG. 9A , an assembly may be fixed with frame body  400  as a jig. The brazing material may be disposed on an inner surface of frame body  400  or may not be disposed. Frame body  400  as the jig may be detached after joining the pipe-shaped members, or may be used as one member of the metallic case of the battery block. 
     Frame body  400  is used as a jig during the brazing between the pipe-shaped members. Therefore, it may be preferable that a coefficient of linear expansion of frame body  400  be the same as that of the pipe-shaped members. This is in order for an assembly of the pipe-shaped members to be reliably maintained by the frame body during the heating of the brazed joints and in order for stress not to be applied to pipe-shaped metallic plates  30  ( 30   a ,  30   b , . . . ,  30   e ). Therefore, for example, as shown in  FIG. 9B , the coefficient of linear expansion of the frame body is adjusted by using a frame body obtained by assembling stainless steel plate  400 - 1  and aluminum frame  400 - 2 . Stainless steel plate  400 - 1  prevents pipe-shaped member  30  and aluminum frame  400 - 2  from joining to each other. 
     As shown in  FIGS. 10A to 10C , in addition to the plurality of the pipe-shaped members, the assembly may also include metallic member  450  ( 450   a ,  450   b , or  450   c ) that is inserted in the gap between the pipe-shaped members. This is because, when metallic member  450  inserted in the gap is provided, thermal capacity of the metallic case may be increased. Specifically, as shown in  FIG. 10A , the gap may be completely filled with inserting metallic member  450   a  in the gap. In addition, when the thermal capacity of the metallic case can be increased, the gap may not be completely filled. For example, the gap may not be completely filled with inserting metallic member  450   b  having a triangular prism shape in the gap as shown in  FIG. 10B  or with inserting columnar metallic member  450   c  in the gap as shown in  FIG. 10C . 
     On the other hand, the gap between the pipe-shaped members in the assembly may be left as is in a hollow state. This is because it is easy to heat or cool the battery block by allowing a coolant to flow through the gap or disposing a heater therein. For example, as shown in  FIG. 11 , coolant gas  500  may be allowed to flow through the gap. 
     After the metallic case is obtained by heating assembly  30  of pipe-shaped metallic plates  30   a ,  30   b , . . . to be brazed to each other, the unit cell is accommodated in each pipe-shaped member  31 , and other members necessary for a battery are added thereto, whereby the battery block is obtained. The unit cell is commonly covered with a metallic case, but may be further covered with an insulation sheet. The insulation sheet is commonly a resin film, and the thickness thereof is 45 to 75 μm. 
     Method of Manufacturing Battery Block 
     Hereinafter, as an example, a method of manufacturing the battery block (metallic case) of the invention will be described with reference to  FIGS. 12A to 12D , and  FIG. 13 . 
     (a) First, metallic plate  230  (refer to  FIG. 12A ) including core material  210  and brazing material layer  220  as shown in  FIG. 12A  is prepared. Then, metallic plate  230  is bent to constitute mating. faces  35  to obtain pipe-shaped metallic plate  30   a  in which brazing material layer  220  is arranged on an outer circumferential surface of core material  210  as shown in  FIG. 12B . This process is repetitively performed to obtain a plurality of pipe-shaped metallic plates  30   a ,  30   b , . . . ,  30   e.    
     (b) The plurality of pipe-shaped metallic plates  30   a ,  30   b , . . . ,  30   e  are brought into contact with each other and are fixed to obtain assembly  30  of pipe-shaped metallic plates  30   a ,  30   b , . . . ,  30   e . Specifically, pipe-shaped metallic plates  30   a ,  30   b , . . . ,  30   e  are brought into contact with each other and are temporarily fixed to obtain assembly  30 . Then, as shown in  FIG. 12C , assembly  30  is fixed with frame body  400 . 
     (c) Assembly  30  of the pipe-shaped metallic plates is heated. Mating surfaces  35  of pipe-shaped metallic plates  30   a ,  30   b , . . . ,  30   e  are brazed to obtain assembly  31  of pipe-shaped members  31   a ,  31   b , . . . ,  31   e . In addition, pipe-shaped metallic plates  30   a ,  30   b , . . . ,  30   e  are brazed to each other. According to this process, protrusion  38  formed from the brazing material as shown in  FIG. 12D  is formed. In this manner, the metallic case may be obtained. 
     (d) Furthermore, as shown in  FIG. 13 , unit cells  40   a ,  40   b , . . . ,  40   e  are accommodated in the plurality of pipe-shaped members  31   a ,  31   b , . . . ,  31   e  of the metallic case of  FIG. 12D , respectively. Then, members necessary for a battery are added. 
     In this manner, a battery block is manufactured. In addition, unit cell  40  may be provided with insulation sheet  45  that covers the unit cell. 
     Hereinbefore, the method of manufacturing the battery block was described, but the method of manufacturing the battery block is not limited to the above-described manufacturing method. For example, instead of the above-described process (a), as shown in  FIG. 5B , metallic plate  200  is bent to constitute mating faces  35 , thereby obtaining pipe-shaped metallic plate  30   a . In this case, it is preferable to dispose the brazing material on the outer circumferential surface of the assembly before proceeding to the (c) process after the above-described process (b). 
     Next, an operation effect of the method of manufacturing the battery block related to the invention will be described in comparison with a method of manufacturing a battery block in the related art. 
     In the related art, when the pipe-shaped member is formed from a cast metal, since a raw material of a mold is sand, surface accuracy of the mold is poor, and surface accuracy of a pipe-shaped member that is a transcript of the mold also decreases. In addition, in a case of obtaining an aluminum pipe-shaped member, due to a variation in components of an aluminum molten metal or the like, a cavity may occur. Therefore, in addition to necessity of a secondary processing to increase the surface accuracy, it is difficult to remove the occurred cavity. In addition, it may be considered that the pipe-shaped member is obtained by a drawing processing. However, when it is intended to decrease the thickness of the pipe-shaped member, shaping accuracy may decrease, and shaping itself is difficult. 
     Conversely, according to the method of manufacturing the battery block related to the invention, since the metallic plate is bent to obtain the pipe-shaped member, it is possible to simply increase shaping accuracy of a portion of the battery block, in which the unit cell is accommodated. Accordingly, in the battery block that is obtained by the method of manufacturing the battery block of the invention, since vibration of the unit cell that is accommodated may be suppressed, it is difficult for a performance as a battery block storage battery to deteriorate. In addition, this battery block is light and compact. Examples of use of the battery block utilizing this characteristic include a storage battery mounted in a vehicle. 
     The disclosure of Japanese Patent Application No. 2011-120473, filed on May 30, 2011, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. 
     INDUSTRIAL APPLICABILITY 
     The battery block of the invention includes a plurality of unit cells and a metallic case that accommodates the unit cells, and shaping accuracy of the metallic case is high. Therefore, vibration of the unit cells that are accommodated is suppressed, and a function of each of the unit cells is appropriately exhibited. Furthermore, the metallic case may be simply manufactured at a lower cost. 
     REFERENCE SIGNS LIST 
     
         
           10  Electrode plate 
           20  Holder 
           30  Pipe-shaped metallic plate 
           31 : Pipe-shaped member 
           30 - 1  Circular pipe 
           30 - 2  Polygonal pipe 
           32  Penetration slot 
           33  Notch 
           35  Mating face 
           38  Protrusion 
           40  Unit cell 
           41  Electrode 
           42  Electrode 
           45  Insulation sheet covering unit cell 
           50  Holder 
           60  Electrode plate 
           100  Battery block 
           200  Metallic flat plate 
           210  Core material 
           220  Brazing material layer 
           230  Metallic plate 
           240  Brazing sheet 
           250  Brazing paste 
           300  Half-pipe-shaped metallic plate 
           400  Frame body 
           400 - 1  Stainless steel plate 
           400 - 2  Aluminum frame 
           450  Metallic member 
           500  Coolant gas