Patent Publication Number: US-2022217865-A1

Title: Circuit structure

Description:
TECHNICAL FIELD 
     The present disclosure relates to a circuit structure. 
     BACKGROUND ART 
     For example, a circuit structure including a metal battery case that houses a relay therein is disclosed in JP 2018-93711A. This circuit structure includes a relay, a first bus bar connected to the relay, a heat conduction sheet arranged between the relay and the first bus bar, and a heat conduction sheet arranged between the first bus bar and the battery case. The heat conduction sheets are each sandwiched between the first bus bar and the relay or between the first bus bar and the battery case, whereby the efficiency with which the relay is cooled is improved due to heat from the relay being transferred from the relay to the first bus bar and from the first bus bar to the battery case. 
     CITATION LIST 
     Patent Documents 
     
         
         Patent Document 1: JP 2018-93711A 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     Incidentally, heat conduction sheets of this type can be in contact with members in a state in which the adhesion therebetween is high and enhance heat conduction efficiency by being sandwiched between the members and being appropriately compressed. 
     However, there are cases in which a heat conduction sheet is excessively compressed due to the manufacturing tolerance of members forming a circuit structure or the assembly tolerance when the members are attached to each other. If a heat conduction sheet is excessively compressed, there is a concern that members may be damaged as a result of high stress being applied to portions where the members are connected to one another due to the resilience of the heat conduction sheet. 
     The present specification discloses a technique for preventing stress from being applied to members while improving cooling efficiency. 
     Solution to Problem 
     A circuit structure according to the present disclosure is a circuit structure including: a heat-generating member; at least one connection conductor; at least one insulative heat transfer member; and an insulative base member, wherein the heat-generating member generates heat as a result of being energized, the connection conductor is connected to the heat-generating member in a heat-transferable state, the heat transfer member is formed in the shape of a heat-transferable sheet, the base member includes a base main body and a positioning portion, the base main body, together with the connection conductor, sandwiches the heat transfer member, and the positioning portion is formed so as to protrude from the base main body, and positions the connection conductor relative to the base main body as a result of coming into contact with the connection conductor. 
     Advantageous Effects of Invention 
     According to the present disclosure, the application of stress to members can be suppressed while improving cooling efficiency. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exploded perspective view of a circuit structure pertaining to an embodiment. 
         FIG. 2  is a perspective view of the circuit structure. 
         FIG. 3  is a partial plan view of the circuit structure. 
         FIG. 4  is a cross-sectional view taken along line A-A in  FIG. 3 . 
         FIG. 5  is a cross-sectional view taken along line B-B in  FIG. 3 . 
         FIG. 6  is a perspective view of a base member. 
         FIG. 7  is a perspective view in which first heat transfer sheets have been attached to the base member. 
         FIG. 8  is a perspective view in which connection conductors have been attached to the base member. 
         FIG. 9  is a perspective view in which a relay has been attached to the base member. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Description of Embodiments of Present Disclosure 
     First, embodiments of the present disclosure will be listed and described. 
     (1) A circuit structure including: a heat-generating member; at least one connection conductor; at least one insulative heat transfer member; and an insulative base member, wherein the heat-generating member generates heat by being energized, the connection conductor is connected to the heat-generating member in a heat-transferable state, the heat transfer member is formed in the shape of a heat-transferable sheet, the base member includes a base main body and a positioning portion, the base main body, together with the connection conductor, sandwiches the heat transfer member, and the positioning portion is formed so as to protrude from the base main body, and positions the connection conductor relative to the base main body as a result of coming into contact with the connection conductor. 
     Due to the connection conductor coming into contact with the positioning portion, the gap between the connection conductor and the base member can be prevented from becoming less than or equal to a predetermined dimension. That is, the connection conductor and the base main body can be brought in contact with the heat transfer member while preventing the heat transfer member sandwiched between the base main body and the connection conductor from being excessively compressed. Thus, the efficiency with which the heat-generating member is cooled can be improved due to the heat from the heat-generating member being transferred from the heat-generating member to the connection conductor and from the connection conductor to the base member. Furthermore, since the heat transfer member is not excessively compressed by the connection conductor, stress originating from the resilience of the heat transfer member can be prevented from being applied to the members and the members can be prevented from being damaged. 
     (2) The positioning portion is arranged in the outer periphery of the heat transfer member. The positioning portion can also be used as a guide for attaching the heat transfer member to the base main body. 
     (3) The connection conductor includes a member connection portion and an extending portion, the member connection portion can be connected to the heat-generating member, the extending portion extends in the shape of a plate from the member connection portion, and the positioning portion is formed so as to be capable of coming into contact with the entire outer peripheral edge portion of the extending portion. 
     Since the positioning portion comes into contact with the entire outer peripheral edge portion of the extending portion, the connection conductor can be more reliably positioned by the positioning portion compared to a case in which the positioning portion comes into contact with one end of the extending portion, for example. Thus, the heat transfer member can be reliably prevented from being excessively compressed by the connection conductor. 
     (4) The heat transfer member is formed so as to be elastically compressible, and the protruding length of the positioning portion from the base main body is set to be equal to the thickness of the heat transfer member when compressed by a predetermined amount. Here, the term “equal” is used to include both a case in which the protruding length of the positioning portion from the base main body and the thickness of the heat transfer member when compressed by the predetermined amount are equal and a case in which, even if the two dimensions are not equal, the two dimensions can be regarded as being substantially equal. 
     The heat transfer member can be prevented from being excessively compressed by the predetermined amount or more when the connection conductor is pressed toward the base main body. 
     (5) The base member further includes a plurality of locking portions, and the plurality of locking portions lock, from the side opposite from the heat transfer member, the connection conductor compressing the heat transfer member. 
     Due to the retaining portions locking, from the side opposite from the heat transfer member, the connection conductor compressing the heat transfer member, the heat transfer member can be kept in a state in which the heat transfer member is compressed by the predetermined amount by the connection conductor and the base main body. Thus, a state in which the heat transfer member is brought in close contact with the connection conductor and the base main body in an appropriate manner can be maintained, and the heat transfer efficiency of the heat transfer member can be improved. 
     (6) The heat-generating member and the connection conductor are connected in a heat-transferable state by a fastening member, the connection conductor has an insertion hole into which a shaft portion of the fastening member is inserted, and the insertion hole is formed so as to be elongated in the direction in which the connection conductor comes into contact with the positioning portion. 
     The shaft portion of the fastening member can move inside the insertion hole in the direction in which the connection conductor comes into contact with the positioning portion. That is, the assembly tolerance occurring between the heat-generating member, the connection conductor, and the positioning portion can be absorbed by the insertion hole. Thus, stress originating from the assembly tolerance can be prevented from being applied to the members and the members can be prevented from being damaged. 
     (7) A metal bracket and at least one second heat transfer member are further included, the base member is fixed to the bracket, the second heat transfer member is formed in the shape of a heat-transferable sheet and sandwiched between the base main body and the bracket, the base main body further includes a second positioning portion, and the second positioning portion is formed so as to protrude toward the bracket side from the base main body, and positions the bracket relative to the base main body as a result of coming into contact with the bracket. 
     The heat from the heat-generating member transferred to the base member can be released to the bracket via the second heat transfer member. Furthermore, the second heat transfer member is similar to the heat transfer member in that the gap between the bracket and the base main body can be prevented from becoming less than or equal to a predetermined dimension due to the bracket coming into contact with the second positioning portion. Thus, the second heat transfer member can be prevented from being excessively compressed. 
     That is, since the second heat transfer member is not excessively compressed by the bracket, stress originating from the resilience of the second heat transfer member can be prevented from being applied to the members and the members can be prevented from being damaged. 
     Details of Embodiment of Present Disclosure 
     A specific example of a circuit structure  10  according to the present disclosure will be described with reference to the drawings below. Note that the present disclosure is not limited to these examples, and is intended to include all modifications that are indicated by the claims and are within the meaning and scope of equivalents of the claims. 
     Embodiment 
     One embodiment of the present disclosure will be described with reference to  FIGS. 1 to 9 . 
     [Circuit Structure  10 ] 
     The circuit structure  10  in the present embodiment is attached to a frame of an unillustrated battery pack that is mounted in a vehicle such as an electric automobile or a hybrid automobile, for example, and controls the electric power of the battery pack. 
     While the circuit structure  10  can be oriented in any direction, in the following description, the direction indicated by arrow Z is regarded as the upward direction, the direction indicated by arrow Y is regarded as the rearward direction, and the direction indicated by the arrow X is regarded as the rightward direction. Furthermore, when more than one of the same member is provided, the reference symbol therefor may be provided to only some of the members and may be omitted for the rest. 
     As illustrated in  FIG. 1 , the circuit structure  10  includes a relay (one example of a “heat-generating component”)  20 , a pair of connection conductors  30 , a pair of first heat transfer sheets (one example of the “heat transfer member”)  40 , a base member  50 , a pair of second heat transfer sheets (one example of the “second heat transfer member”)  70 , and a bracket  80 . 
     [Relay  20 ] 
     The relay  20  is a mechanical relay and includes a rectangular solid-shaped relay main body  22 , a pair of terminal portions  24 , and a plurality of fixing portions  26 , as illustrated in  FIGS. 1 to 3 . 
     The relay main body  22  has an unillustrated contact portion and coil portion therein. On the front surface of the relay main body  22 , the pair of terminal portions  24  are arranged side by side in the left-right direction. 
     When a current is applied between the pair of terminal portions  24  via the contact portion of the relay main body  22 , heat generated by the contact portion is transferred to the pair of terminal portions  24  and the pair of terminal portions  24  emit heat. The terminal portions  24  each have a bolt hole  25  that extends rearward. 
     The plurality of fixing portions  26  are formed so as to protrude in the shape of plates. Two fixing portions  26  are formed on each of the two side surfaces on the two sides of the relay main body  22  in the left-right direction. The fixing portions  26  have insertion holes  27  penetrating the fixing portions  26  in the top-bottom direction. The relay  20  is fixed to the base member  50  as a result of bolts  28  being inserted into the insertion holes  27  and the bolts  28  being fastened to later-described bolt fastening portions  52  of the base member  50 . 
     [Connection Conductors  30 ] 
     The pair of connection conductors  30  are each formed by machining an electroconductive metal plate member. As illustrated in  FIGS. 1 to 4 , the connection conductors  30  each include a member connection portion  32  and an extending portion  34 . 
     The member connection portions  32  have the shape of rectangular flat plates that extend from the positions of the terminal portions  24  of the relay  20  to below the relay main body  22 . 
     The member connection portions  32  are arranged so as to extend in the top-bottom direction along the front surfaces of the terminal portions  24  of the relay  20 . The member connection portions  32  have bolt insertion holes (one example of the “insertion hole”)  33  that penetrate the member connection portions  32  in the front-rear direction, which is the plate thickness direction thereof. The bolt insertion holes  33  are long holes that are elongated in the top-bottom direction, which is the direction in which the relay  20  and the connection conductors  30  are attached to the base member  50 . The connection conductors  30  are heat conductively connected to the terminal portions  24  of the relay  20  by inserting shaft portions T 1  of bolts T that are fastening members into the bolt insertion holes  33  of the member connection portions  32  and fastening the shaft portions T 1  to the bolt holes  25  of the terminal portions  24 . 
     The extending portions  34  are formed in the shape of rectangular plates extending rearward from the bottom edges of the member connection portions  32 . The extending portions  34  are arranged below the relay main body  22  in a state in which the outer peripheral edge portions of the extending portions  34  protrude slightly from the projection plane of the relay main body  22 , as illustrated in  FIG. 3 . 
     Accordingly, when the connection conductors  30  are attached to the relay  20 , heat from the terminal portions  24  of the relay  20  is transferred to the extending portions  34  via the member connection portions  32  of the connection conductors  30 . The first heat transfer sheets  40  are attached to the bottom surfaces of the extending portions  34 , which are on the opposite side from the relay main body  22  side. 
     [First Heat Transfer Sheets  40 ] 
     The first heat transfer sheets  40  transfer heat from the connection conductors  30  to the base member  50 . The first heat transfer sheets  40  are formed in the shape of rectangular sheets that are elongated in the front-rear direction and that are flat with a small thickness in the top-bottom direction using an insulative synthetic resin having greater heat conductivity than air. 
     As illustrated in  FIGS. 4 and 5 , the first heat transfer sheets  40  have unillustrated adhesive layers provided on the two surfaces thereof on both sides in the top-bottom direction, and are affixed to the bottom surfaces of the extending portions  34  of the connection conductors  30  and the top surfaces of later-described mounting portions  51 A of the base member  50  using these adhesive layers. 
     The first heat transfer sheets  40  can be elastically compressed in the top-bottom direction, which is the thickness direction thereof. The first heat transfer sheets  40  are in close contact with the extending portions  34  and the mounting portions  51 A due to being compressed by a predetermined amount from both sides in the top-bottom direction by the extending portions  34  and the mounting portions  51 A, as illustrated in  FIGS. 4 and 5 . 
     [Base Member  50 ] 
     As illustrated in  FIGS. 4 and 5 , the relay  20 , the pair of connection conductors  30 , and the first heat transfer sheets  40  are attached to the base member  50  from above, and the second heat transfer sheets  70  and the bracket  80  are attached to the base member  50  from below. The base member  50  is formed using an insulative synthetic resin. As illustrated in  FIG. 6 , the base member  50  includes a base main body  51 , first positioning portions (one example of the “positioning portion”)  54 , second positioning portions  55 , a plurality of locking portions  56 , rear stopping portions  58 , and a protective wall  59 . 
     The base main body  51  is formed in the shape of a rectangular flat plate on which the relay  20  and the pair of connection conductors  30  can be arranged. 
     Two bolt fastening portions  52  extending upward from the base main body  51  are formed on each of the two sides of the base main body  51  in the left-right direction. The relay  20  is fixed to the base member  50  as a result of the fixing portions  26  of the relay  20  being fastened by bolts to these bolt fastening portions  52 . 
     A pair of through holes  53  penetrating the base main body  51  in the top-bottom direction are formed between the regions of the base main body  51  where the bolt fastening portions  52  are arranged and the side edges of the base main body  51  on both sides in the left-right direction. 
     The base member  50  is fixed to the bracket  80  as a result of later-described screw fastening portions  86  of the bracket  80  being inserted into these through holes  53 , as illustrated in  FIG. 5 , and screws  87  being fastened to the screw fastening portions  86 . 
     As illustrated in  FIGS. 5 and 6 , a through hole  53 A, which is one of the pair of through holes  53 , is a long hole that is elongated in the left-right direction. The through hole  53 A can absorb the difference in expansion between the base main body  51  and the bracket  80  if the base main body  51  undergoes thermal expansion due to heat from the relay  20 . 
     As illustrated in  FIGS. 4 to 6 , the center of the base main body  51  is configured as a pair of mounting portions  51 A on which the pair of first heat transfer sheets  40  and the later-described pair of second heat transfer sheets  70  are arranged. 
     The pair of mounting portions  51 A are arranged so that they are side by side in the left-right direction. The mounting portions  51 A are each formed in the shape of a rectangle that is slightly larger in the front-rear and left-right directions than the first heat transfer sheets  40  and the second heat transfer sheets  70 . The pair of first heat transfer sheets  40  are placed on the top surfaces of the pair of mounting portions  51 A, and the pair of later-described second heat transfer sheets  70  are arranged on the bottom surfaces of the pair of mounting portions  51 A. 
     In the outer periphery of each mounting portion  51 A in the base main body  51 , a first positioning portion  54  that protrudes upward from the base main body  51  and a second positioning portion  55  that protrudes downward from the base main body  51  are provided. 
     As illustrated in  FIGS. 4 to 6 , the first positioning portions  54  are formed in the shape of continuous rectangular frames that are elongated in the front-rear direction so as to surround the mounting portions  51 A continuously over the entire periphery thereof. The long-side length of the first positioning portions  54  is slightly longer than the long-side length of the extending portions  34  of the connection conductors  30 , and the short-side length of the first positioning portions  54  is equal to the short-side length of the extending portions  34 . Here, the term “equal” is used to include both a case in which the short-side length of the first positioning portions  54  and the short-side length of the extending portions  34  are equal and a case in which, even if the two dimensions are not equal, the two dimensions can be regarded as being substantially equal. 
     Accordingly, when the first heat transfer sheets  40  affixed to the connection conductors  30  are placed on the mounting portions  51 A, the first positioning portions  54  continuously surround the outer periphery of the first heat transfer sheets  40  and the first positioning portions  54  are arranged below the extending portions  34  to as to extend along the outer peripheral edge portions of the extending portions  34 . 
     The protruding length of the first positioning portions  54  from the base main body  51  is set to be equal to the thickness of the first heat transfer sheets  40  when sandwiched by the extending portions  34  and the mounting portions  51 A and compressed by the predetermined amount. Here, the term “equal” is used to include both a case in which the protruding length of the first positioning portions  54  from the base main body  51  and the thickness of the first heat transfer sheets  40  when compressed by the predetermined amount are equal and a case in which, even if the two dimensions are not equal, the two dimensions can be regarded as being substantially equal. 
     That is, even if the first heat transfer sheets  40  are compressed due to being sandwiched from both sides in the top-bottom direction by the extending portions  34  and the mounting portions  51 A the first positioning portions  54  come into contact with the entire outer peripheral edge portions of the extending portions  34  in the top-bottom direction and the extending portions  34  are positioned in the top-bottom direction relative to the base main body  51 , as illustrated in  FIGS. 4 and 5 . Thus, the first heat transfer sheets  40  are prevented from being excessively compressed. 
     As illustrated in  FIGS. 4 and 5 , the second positioning portions  55  are formed in the shape of rectangular frames that are elongated in the front-rear direction so as to surround the second heat transfer sheets  70  attached to the bottom surfaces of the mounting portions  51 A continuously over the entire periphery thereof. The long-side and short-side lengths of the second positioning portions  55  are set to be equal to the long-side and short-side lengths of the first positioning portions  54 . 
     The protruding length of the second positioning portions  55  from the base main body  51  is set to be equal to the thickness of the second heat transfer sheets  70  attached to the bottom surfaces of the mounting portions  51 A when the second heat transfer sheets  70  are sandwiched from both sides in the top-bottom direction by the mounting portions  51 A and a later-described bracket main body  82  of the bracket  80  and compressed by a predetermined amount. Here, the term “equal” is used to include both a case in which the protruding length of the second positioning portions  55  from the base main body  51  and the thickness of the second heat transfer sheets  70  when compressed by the predetermined amount are equal and a case in which, even if the two dimensions are not equal, the two dimensions can be regarded as being substantially equal. 
     As illustrated in  FIG. 6 , the plurality of locking portions  56  are formed so that one locking portion  56  is present at each of the two sides of each first positioning portion  54  in the left-right direction. The two locking portions  56  positioned between the pair of first positioning portions  54  are arranged so as to be displaced from one another in the front-rear direction. 
     As illustrated in  FIG. 5 , the locking portions  56  each include an elastic piece  56 A that extends upward from the base main body  51 , and a locking projection  56 B that protrudes from the upper end of the elastic piece  56 A toward the inner side, which is the first positioning portion  54  side. 
     The elastic pieces  56 A are elastically displaceable away from the first positioning portions  54 . The locking projections  56 B are formed so as to protrude to positions above the first positioning portions  54 . The bottom surfaces of the locking projections  56 B are locking surfaces  56 C that face the first positioning portions  54  in the top-bottom direction. The locking surfaces  56 C lock, in the top-bottom direction, to the extending portions  34  of the connection conductors  30  arranged above the first positioning portions  54 , and thereby hold the connection conductors  30  compressing the first heat transfer sheets  40  by the predetermined amount. 
     That is, the first heat transfer sheets  40  are compressed by the predetermined amount due to the connection conductors  30  being held by the locking portions  56 . Thus, the first heat transfer sheets  40 , the extending portions  34 , and the mounting portions  51 A are brought in close contact with one another in an appropriate manner, and the heat transfer efficiency of the first heat transfer sheets  40  is improved. 
     As illustrated in  FIGS. 3 and 4 , the rear stopping portions  58  are formed in the shape of flat plates that extend in the left-right direction so as to continue from the rear portions of the first positioning portions  54 . 
     The rear stopping portions  58  stop the connection conductors  30  from the rear by coming into contact with rear end edges  34 A of the extending portions  34  of the connection conductors  30  arranged on the first positioning portions  54 . 
     As illustrated in  FIG. 6 , the protective wall  59  is formed extending upward from the outer peripheral edge of the base main body  51  so as to extend along the outer peripheral edge of the base main body  51 . As illustrated in  FIG. 5 , the height position of the upper end portion of the protective wall  59  is substantially the same as the height position of the lower end portions of the terminal portions  24  of the relay  20 . Thus, the lower end portion of the relay  20 , the connection conductors  30 , and the first heat transfer sheets  40  are protected from other members by the protective wall  59 . 
     [Second Heat Transfer Sheets  70 ] 
     As illustrated in  FIG. 1 , the second heat transfer sheets  70  are provided with a configuration similar to that of the first heat transfer sheets  40 , and thus description of the configuration of the second heat transfer sheets  70  will be omitted. The second heat transfer sheets  70  transfer heat from the base member  50  to the bracket  80 . 
     The second heat transfer sheets  70  are affixed to the bottom surfaces of the mounting portions  51 A of the base member  50  and to the bracket main body  82  of the bracket  80  using unillustrated adhesive layers. 
     As illustrated in  FIGS. 4 and 5 , the second heat transfer sheets  70  are in close contact with the mounting portions  51 A and the bracket main body  82  of the bracket  80  due to being sandwiched from both sides in the top-bottom direction by the mounting portions  51 A and the bracket main body  82  and being compressed by a predetermined amount. 
     [Bracket  80 ] 
     The bracket  80  is a member to which the base member  50  is attached and which is attached to a battery pack frame, and is formed from a heat conductive metal. As illustrated in  FIG. 1 , the bracket  80  includes the bracket main body  82 , and an outer peripheral plate  84  that extends upward from the outer peripheral edge portion of the bracket main body  82 . 
     The bracket main body  82  is formed in the shape of a rectangular flat plate. As illustrated in  FIGS. 4 and 5 , the second heat transfer sheets  70  and the second positioning portions  55  of the base member  50  are placed on the top surface of the bracket main body  82 . 
     As illustrated in  FIG. 5 , the screw fastening portions  86 , which form a pair and extend upward, are formed on the two sides of the bracket main body  82  in the left-right direction. 
     The base member  50  is fixed to the bracket  80  as a result of the pair of screw fastening portions  86  being inserted into the through holes  53  in the base main body  51  of the base member  50  when the base member  50  is arranged on the bracket main body  82  and the screws  87  being fastened to the pair of screw fastening portions  86 . 
     When the base member  50  is fixed to the bracket main body  82 , the second positioning portions  55  continuously surround the outer periphery of the second heat transfer sheets  70 , and the second heat transfer sheets  70  are compressed by the predetermined amount under the weight of the members attached to the base member  50  from above. Thus, the second heat transfer sheets  70  are brought in close contact with the mounting portions  51 A and the bracket main body  82 . 
     The present embodiment has a configuration as described above, and an example of a process for assembling the circuit structure  10  will be described next. 
     First, the base member  50  is prepared, as illustrated in  FIG. 6 , and the two first heat transfer sheets  40  are placed on the pair of mounting portions  51 A of the base member  50 , as illustrated in  FIG. 7 . Here, the first heat transfer sheets  40  are arranged on the mounting portions  51 A without misalignment due to the first heat transfer sheets  40  being arranged inside the first positioning portions  54  using the first positioning portions  54  as guides. Furthermore, in a state in which the first heat transfer sheets  40  have been arranged on the mounting portions  51 A, the first heat transfer sheets  40  protrude slightly upward past the first positioning portions  54 . 
     Next, as illustrated in  FIG. 8 , the connection conductors  30  are attached to the first positioning portions  54  of the base member  50 . In this assembly process, the extending portions  34  are arranged on the first positioning portions  54  due to the extending portions  34  of the connection conductors  30  interfering with the locking projections  56 B of the locking portions  56  of the base member  50  and the elastic pieces  56 A undergoing elastic deformation. When the extending portions  34  are arranged on the first positioning portions  54 , the extending portions  34 , together with the mounting portions  51 A, compress the first heat transfer sheets  40  from both sides in the top-bottom direction by the predetermined amount, and the first heat transfer sheets  40  are brought in close contact with the extending portions  34  and the mounting portions  51 A. Furthermore, when the extending portions  34  are arranged on the first positioning portions  54 , the interference between the extending portions  34  and the locking projections  56 B is released, and the elastic pieces  56 A elastically return to their original positions. Then, the extending portions  34  and the locking surfaces  56 C of the locking projections  56 B of the locking portions  56  lock to one another in the top-bottom direction, and the extending portions  34  are held in a state in which the extending portions  34 , together with the mounting portions  51 A, compress the first heat transfer sheets  40  by the predetermined amount. 
     Next, the relay  20  is fixed to the base member  50  as a result of the relay  20  being attached to the base member  50  so that the fixing portions  26  of the relay  20  are placed on the bolt fastening portions  52  of the base member  50 , and the fixing portions  26  being fastened by bolts to the bolt fastening portions  52 . 
     Next, the bolt insertion holes  33  in the member connection portions  32  of the connection conductors  30  and the bolt holes  25  in the terminal portions  24  of the relay  20  are positioned relative to one another, and the shaft portions T 1  of the bolts T, which are fastening members, are fastened to the bolt holes  25 , as illustrated in  FIG. 9 . Thus, the terminal portions  24  of the relay  20  and the member connection portions  32  of the connection conductors  30  are connected in a heat-transferable state. 
     Here, when the extending portions  34  are pressed downward as the bolt insertion holes  33  and the bolt holes  25  are positioned relative to one another, the extending portions  34  are positioned relative to the base main body  51  in the top-bottom direction due to the extending portions  34  and the first positioning portions  54  coming into contact with one another in the top-bottom direction, as illustrated in  FIGS. 4 and 5 . Thus, the first heat transfer sheets  40  are prevented from being excessively compressed. Note that in the present embodiment, the bolts T are fastened to the bolt holes  25  in a state in which the extending portions  34  are pressed downward, as illustrated in  FIGS. 4 and 5 . Accordingly, clearances are formed between the extending portions  34  and the locking surfaces  56 C of the locking portions  56 . 
     Next, the second heat transfer sheets  70  are affixed to the bottom surfaces of the mounting portions  51 A of the base member  50 . Here, the second heat transfer sheets  70  are arranged on the mounting portions  51 A without misalignment due to the second positioning portions  55  guiding the second heat transfer sheets  70 . 
     Next, the base member  50  is fixed to the bracket  80  as a result of the screw fastening portions  86  of the bracket  80  being inserted into the through holes  53  in the base member  50  and the screws  87  being fastened to the screw fastening portions  86 . Here, when the base member  50  is fixed to the bracket  80 , the second heat transfer sheets  70  are compressed by the predetermined amount under the weight of the members attached to the base member  50  from above, and the mounting portions  51 A and the bracket main body  82  are brought in close contact, as illustrated in  FIGS. 4 and 5 . 
     Furthermore, in the case in which the base member  50  is fixed to the bracket  80  as well, the base main body  51  is positioned relative to the bracket main body  82  in the top-bottom direction due to the second positioning portions  55  and the bracket main body  82  coming into contact with one another in the top-bottom direction. Thus, the second heat transfer sheets  70  are prevented from being excessively compressed. 
     The circuit structure  10  is produced in such a manner. 
     Subsequently, the actions and effects of the circuit structure  10  will be described. 
     For example, in a case in which the extending portions  34  are pressed downward due to the manufacturing tolerance of the relay  20 , the connection conductors  30 , and the base member  50  or the assembly tolerance when the members are attached to each other, the first heat transfer sheets  40  may be excessively compressed by the connection conductors  30 . If the first heat transfer sheets  40  are excessively compressed by the connection conductors  30 , there is a concern that the members may be damaged by high stress applied to portions where the members are connected to one another due to the resilience of the first heat transfer sheets  40 . 
     Thus, the present inventor, etc., conducted diligent investigations to solve the above-described problem and arrived at the configuration of the present embodiment. That is, the present embodiment is a circuit structure  10  including: a relay  20  (heat-generating member); at least one connection conductor  30 ; at least one insulative first heat transfer sheet (heat transfer member)  40 ; and an insulative base member  50 . The relay  20  generates heat as a result of being energized, the connection conductor  30  is connected to the relay  20  in a heat-transferable state, the first heat transfer sheet  40  is formed in the shape of a heat-transferable sheet, the base member  50  includes a base main body  51  and a first positioning portion (positioning portion)  54 , the base main body  51 , together with the connection conductor  30 , sandwiches the first heat transfer sheet  40 , and the first positioning portion  54  is formed so as to protrude from the base main body  51 , and positions the connection conductor  30  relative to the base main body  51  as a result of coming into contact with the connection conductor  30 . 
     As illustrated in  FIGS. 4 and 5 , due to the connection conductor  30  coming into contact with the first positioning portion  54 , the gap between the connection conductor  30  and the base member  50  can be prevented from becoming less than or equal to a predetermined dimension. That is, the connection conductor  30  and the base main body  51  can be brought in contact with the first heat transfer sheet  40  while preventing the first heat transfer sheet  40  sandwiched between the base main body  51  and the connection conductor  30  from being excessively compressed. 
     Thus, the efficiency with which the relay  20  is cooled can be improved due to the heat from the relay  20  being transferred from the relay  20  to the connection conductor  30  and from the connection conductor  30  to the base member  50  via the first heat transfer sheet  40 . Furthermore, since the first heat transfer sheet  40  is not excessively compressed by the connection conductor  30 , stress originating from the resilience of the first heat transfer sheet  40  can be prevented from being applied to the relay  20 , the connection conductor  30 , and the base member  50 . Thus, the relay  20 , the connection conductor  30 , and the base member  50  can be prevented from being damaged. 
     Furthermore, the first positioning portion  54  is arranged in the outer periphery of the first heat transfer sheet  40 , and thus the first positioning portion  54  can also be used as a guide for attaching the first heat transfer sheet  40  to the base main body  51 . 
     Furthermore, the connection conductor  30  includes a member connection portion  32  and an extending portion  34 , the member connection portion  32  can be connected to the relay  20 , the extending portion  34  extends in the shape of a plate from the member connection portion  32 , and the first positioning portion  54  is formed so as to be capable of coming into contact with the entire outer peripheral edge portion of the extending portion  34 . 
     Since the first positioning portion  54  comes into contact with the entire outer peripheral edge portion of the extending portion  34 , the connection conductor  30  can be more reliably positioned by the first positioning portion  54  compared to a case in which the first positioning portion comes into contact with one end of the extending portion, for example. Thus, the first heat transfer sheet  40  can be reliably prevented from being excessively compressed by the connection conductor  30 . 
     The first heat transfer sheet  40  is formed so as to be elastically compressible, and the protruding length of the first positioning portion  54  from the base main body  51  is set to be equal to the thickness of the first heat transfer sheet  40  when compressed by a predetermined amount. 
     The first heat transfer sheet  40  can be prevented from being excessively compressed by the predetermined amount or more when the connection conductor  30  is pressed toward the base main body  51 . 
     The base member  50  further includes a plurality of locking portions  56 , and the plurality of locking portions  56  lock, from the side opposite from the first heat transfer sheet  40 , the connection conductor  30  compressing the first heat transfer sheet  40 . 
     Due to the locking portions  56  locking, from the side opposite from the first heat transfer sheet  40 , the connection conductor  30  compressing the first heat transfer sheet  40 , the first heat transfer sheet  40  can be kept in a state in which the first heat transfer sheet  40  is compressed by the predetermined amount by the connection conductor  30  and the base main body  51 . Thus, a state in which the first heat transfer sheet  40  is brought in close contact with the connection conductor  30  and the base main body  51  in an appropriate manner can be maintained, and the heat transfer efficiency of the first heat transfer sheet  40  can be improved. 
     The relay  20  and the connection conductor  30  are connected in a heat-transferable state by a bolt (fastening member) T, the connection conductor  30  has a bolt insertion hole (insertion hole)  33  into which a shaft portion T 1  of the bolt T is inserted, and the bolt insertion hole  33  is formed so as to be elongated in the direction in which the connection conductor  30  comes into contact with the first positioning portion  54 , as illustrated in  FIG. 4 . 
     The shaft portion T 1  of the bolt T can move inside the bolt insertion hole  33  in the direction in which the connection conductor  30  comes into contact with the first positioning portion  54 . That is, the assembly tolerance occurring between the relay  20 , the connection conductor  30 , and the first positioning portion  54  can be absorbed by the bolt insertion hole  33 . Thus, stress originating from the assembly tolerance can be prevented from being applied to the relay  20 , the connection conductor  30 , and the base member  50 . Accordingly, the relay  20 , the connection conductor  30 , and the base member  50  can be prevented from being damaged. 
     A metal bracket  80  and at least one second heat transfer sheet  70  are further included, the base member  50  is fixed to the bracket  80 , the second heat transfer sheet  70  is formed in the shape of a heat-transferable sheet and sandwiched between the base main body  51  and the bracket  80 , the base main body  51  further includes a second positioning portion  55 , and the second positioning portion  55  is formed so as to protrude toward the bracket  80  side from the base main body  51 , and positions the bracket  80  relative to the base main body  51  as a result of coming into contact with the bracket  80 . 
     The heat from the relay  20  transferred to the base member  50  can be released to the bracket  80  via the second heat transfer sheet  70 . Furthermore, the second heat transfer sheet  70  is similar to the first heat transfer sheet  40  in that the gap between the bracket  80  and the base main body  51  can be prevented from becoming less than or equal to a predetermined dimension due to the bracket  80  coming into contact with the second positioning portion  55  as illustrated in  FIGS. 4 and 5 . Thus, the second heat transfer sheet  70  can be prevented from being excessively compressed. That is, since the second heat transfer sheet  70  is not excessively compressed by the bracket  80 , stress originating from the resilience of the second heat transfer sheet  70  can be prevented from being applied to the bracket  80  and the base member  50 , and the bracket  80  and the base member  50  can be prevented from being damaged. 
     Other Embodiments 
     (1) In the above-described embodiment, a configuration is adopted in which the base member  50  is fixed to a battery pack frame via the second heat transfer sheets  70  and the bracket  80 . However, there is no limitation to this, and a configuration in which the base member is directly fixed to a battery pack frame may be adopted. 
     (2) In the above-described embodiment, the relay  20  is described as one example of a heat-generating component. However, there is no limitation to this, and the heat-generating component may be any electronic component such as a semiconductor relay, a capacitor, or a diode. 
     (3) In the above-described embodiment, a configuration is adopted in which the first heat transfer sheets  40  and the second heat transfer sheets  70  are affixed to the base member  50 , the connection conductors  30 , and the bracket  80  using adhesive layers. However, there is no limitation to this, and a configuration may be adopted in which the heat transfer sheets are not affixed to the base member  50 , the connection conductors  30 , or the bracket  80  due to being held inside the first positioning portions and second positioning portions. 
     (4) In the above-described embodiment, a configuration is adopted in which the extending portions  34  of the connection conductors  30  are arranged below the relay  20 . However, there is no limitation to this, and a configuration may be adopted in which the extending portions extend in a direction away from the relay. 
     (5) In the above-described embodiment, a configuration is adopted in which the first positioning portions  54  and the second positioning portions  55  are formed so as to continuously surround the outer periphery of the first heat transfer sheets  40  or the second heat transfer sheets  70 , and the first positioning portions  54  and the second positioning portions  65  come into contact with the outer peripheral edge portions of the extending portions  34  or the bracket main body  82  continuously over the entire periphery thereof. However, there is no limitation to this, and a configuration may be adopted in which the first positioning portions and the second positioning portions are formed intermittently in the outer periphery of the first heat transfer sheets or second heat transfer sheets, and the first positioning portions and the second positioning portions intermittently come into contact with the outer peripheral edge portions of the extending portions or the bracket main body. 
     LIST OF REFERENCE NUMERALS 
     
         
         
           
               10 : Circuit structure 
               20 : Relay (one example of “heat-generating component”) 
               22 : Relay main body 
               24 : Terminal portion 
               25 : Bolt hole 
               26 : Fixing portion 
               27 : Insertion hole 
               28 : Bolt 
               30 : Connection conductor 
               32 : Member connection portion 
               33 : Bolt insertion hole (one example of “insertion hole”) 
               34 : Extending portion 
               34 A: Rear end edge 
               40 : First heat transfer sheet (one example of “heat transfer member”) 
               50 : Base member 
               51 : Base main body 
               51 A: Mounting portion 
               52 : Bolt fastening portion 
               53 : Through hole 
               53 A: Through hole 
               54 : First positioning portion (one example of “positioning portion”) 
               55 : Second positioning portion 
               56 : Locking portion 
               56 A: Elastic piece 
               56 B: Locking projection 
               56 C: Locking surface 
               58 : Rear stopping portion 
               59 : Protective wall 
               70 : Second heat transfer sheet (one example of “second heat transfer member”) 
               80 : Bracket 
               82 : Bracket main body 
               84 : Outer peripheral plate 
               86 : Screw fastening portion 
               87 : Screw 
             T 1 : Shaft portion 
             T: Bolt (one example of “fastening member”)