Circuit unit

Abstract

The present invention discloses a circuit unit that makes it possible to suppress a thermal effect on a battery module in a state in which the circuit unit is accommodated in the housing of a battery pack.　Provided is a circuit unit 10 in which a battery module 16 is mounted inside a battery pack 12 that is accommodated in a housing 20, said circuit unit 10 comprising: a circuit component part 30 that includes a heat generating component 14; a fan motor 32; a case 34 that accommodates the circuit component part 30 and the fan motor 32; air intake holes 36 that are provided upstream in the air blowing directions α, β of the fan motor 32 of the case 34; air exhaust holes 38 that are provided downstream in the air blowing directions α, β of the fan motor 32 of the case 34; and an exhaust direction restriction unit 40 that directs exhaust from the air exhaust holes 38 in a direction away from the battery module 16.

Description

Circuit Unit

[0001] The present disclosure relates to a circuit unit.

[0002] Patent Document 1 discloses a relay unit as a circuit unit mounted on a vehicle and arranged in a power supply path from a power source to a load. The relay unit in Patent Document 1 includes a fan motor, and employs a structure that promotes heat dissipation from the relay by using air blown by the fan motor to cool a heat-dissipating component fixed to the terminal of the relay, which is a heat-generating component.

[0003] Japanese Patent Application Laid-Open No. 2018-206601

[0004] In recent years, a battery pack, which is one of the power sources installed in a vehicle, may house a circuit unit equipped with a heat-generating component such as a relay, as exemplified in Patent Document 1. In such cases, since the battery pack housing also houses a battery module, it is necessary to minimize the thermal effect of the circuit unit housed in the housing on the battery module, and some kind of countermeasure has been sought.

[0005] Therefore, a circuit unit is disclosed that can suppress the thermal influence on the battery module while housed in the housing of the battery pack.

[0006] The circuit unit of the present disclosure is a circuit unit mounted inside a battery pack in which a battery module is housed within a housing, and comprises a circuit configuration section including heat-generating components, a fan motor, and a case that houses the circuit configuration section and the fan motor, wherein the case has an intake hole provided upstream of the air blowing direction of the fan motor and an exhaust hole provided downstream, and an exhaust direction regulating section that directs exhaust from the exhaust hole in a direction away from the battery module.

[0007] According to the circuit unit of the present disclosure, it is possible to suppress the thermal influence on the battery module while it is housed in the housing of the battery pack.

[0008] FIG. 1 is a perspective view showing a battery pack including a circuit unit according to the first embodiment, with a lid that constitutes a housing removed. FIG. 2 is an enlarged plan view showing a main portion of the battery pack shown in FIG. 1. FIG. 3 is a perspective view showing a positive electrode main body that constitutes a positive electrode circuit unit, which is one of the circuit units according to the first embodiment. FIG. 4 is a perspective view showing the positive electrode main body shown in FIG. 3 with an upper case that constitutes a case removed. FIG. 5 is a plan view showing the positive electrode main body shown in FIG. 3 with an upper case that constitutes a case removed. FIG. 6 is a longitudinal cross-sectional view of the positive electrode main body shown in FIG. 3, enlarging the VI-VI section in FIG. 5. FIG. 7 is a longitudinal cross-sectional view of the positive electrode main body shown in FIG. 3, enlarging the VII-VII section in FIG. 5. FIG. 8 is an exploded perspective view of the positive electrode main body shown in FIG. 3. FIG. 9 is an exploded perspective view showing the circuit components that constitute the positive electrode main body shown in FIG. 3 in an exploded state. FIG. 10 is a perspective view showing a negative electrode main body of a negative electrode circuit unit, which is another circuit unit according to embodiment 1, with the upper case constituting the case removed. FIG. 11 is a plan view showing the negative electrode main body shown in FIG. 10 with the upper case constituting the case removed. FIG. 12 is a longitudinal cross-sectional view of the negative electrode main body shown in FIG. 10, and is an enlarged view of the XII-XII cross section in FIG. 11. FIG. 13 is an exploded perspective view of the negative electrode main body shown in FIG. 10. FIG. 14 is an exploded perspective view showing the circuit components constituting the negative electrode main body shown in FIG. 10 in an exploded state. FIG. 15 is a perspective view showing a positive electrode main body constituting a positive electrode circuit unit, which is one of the circuit units according to embodiment 2. FIG. 16 is a perspective view showing the positive electrode main body shown in FIG. 15 with the upper case constituting the case removed. FIG. 17 is a perspective view showing the positive electrode main body shown in FIG. 16 from the rear side. FIG. 18 is a plan view of the positive electrode main body shown in FIG. 16. Fig. 19 is an enlarged longitudinal sectional view showing a cross section taken along line XIX-XIX in Fig. 18. Fig. 20 is an enlarged longitudinal sectional view showing a cross section taken along line XX-XX in Fig. 18.FIG. 21 is an exploded perspective view of the positive electrode main body shown in FIG. 15 . FIG. 22 is an enlarged perspective view of a main portion of the exploded perspective view of the positive electrode main body shown in FIG. 21 . FIG. 23 is an oblique view showing a state in which an upper case constituting a case in a positive electrode main body constituting a positive electrode circuit unit, which is one of the circuit units according to embodiment 3, is removed. FIG. 24 is an enlarged exploded perspective view of a main portion of the positive electrode main body shown in FIG. 23 in an exploded state. FIG. 25 is a longitudinal cross-sectional view of a positive electrode main body constituting a positive electrode circuit unit, which is one of the circuit units according to variation 1 of embodiment 3, and corresponds to FIG. 20 . FIG. 26 is an enlarged exploded perspective view of a main portion of the positive electrode main body shown in FIG. 25 in an exploded state. FIG. 27 is an oblique view showing a state in which an upper case constituting a case in a positive electrode main body constituting a positive electrode circuit unit, which is one of the circuit units according to variation 2 of embodiment 3, is removed. FIG. 28 is an enlarged exploded perspective view of a main portion of the positive electrode main body shown in FIG. 27 in an exploded state. FIG. 29 is a perspective view showing a state in which an upper case constituting a case in a positive electrode main body constituting a positive electrode circuit unit, which is one of the circuit units according to embodiment 4, is removed. FIG. 30 is a plan view of the positive electrode main body shown in FIG. 29. FIG. 31 is an exploded perspective view of the positive electrode main body shown in FIG. 29. FIG. 32 is an exploded perspective view showing the positive electrode main body shown in FIG. 29 from the rear side. FIG. 33 is a perspective view showing a circuit unit according to another aspect of the present disclosure, with the upper view showing the hinge opening / closing section in an open state and the lower view showing the hinge opening / closing section in a closed state. FIG. 34 is a plan view showing a circuit unit according to yet another aspect of the present disclosure housed in a battery pack. FIG. 35 is a perspective view showing a positive electrode circuit unit, which is one of the circuit units according to yet another aspect of the present disclosure, with the upper case constituting a case in the case removed.

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be listed and described. The circuit unit of the present disclosure is: (1) a circuit unit mounted inside a battery pack in which a battery module is housed in a housing, the circuit unit including a heat-generating component, a fan motor, a case that houses the circuit component and the fan motor, an intake hole provided in the case on the upstream side of the airflow direction of the fan motor, an exhaust hole provided in the case on the downstream side of the airflow direction of the fan motor, and an exhaust direction restrictor that directs exhaust air from the exhaust hole in a direction away from the battery module.

[0010] According to this aspect, even when the air inside the case heated by the heat-generating components is exhausted through the exhaust hole provided in the case by the fan motor, the exhaust from the exhaust hole is directed away from the battery module in the battery pack by the exhaust direction restrictor provided in the circuit unit, thereby making it possible to provide a circuit unit that can suppress the thermal effects on the battery module housed in the battery pack even when used in a state housed in the battery pack housing.

[0011] Here, the exhaust direction restricting portion may be provided separately from the case or may be provided on the case. For example, an exhaust direction restricting portion shaped like a wind deflector may be disposed opposite the exhaust hole, or an exhaust direction restricting portion shaped like a wind deflector may be integrally provided opposite the exhaust hole on the wall of the battery pack housing. Alternatively, the side of the exhaust hole provided on the case may be configured as an inclined surface inclined with respect to the airflow direction of the fan motor, or an air deflector positioned opposite the exhaust hole of the case may be integrally provided or assembled to the case.

[0012] (2) In the above (1), it is preferable that the heat-generating component includes a first heat-generating component having a heat sink thermally connected to a terminal portion, and the first heat-generating component and the heat sink are disposed downstream of the fan motor in the airflow direction. Heat from the heat-generating component is efficiently transferred to the heat sink from the terminal portion, through which heat is transferred most, and heat dissipation from the heat sink is further promoted by utilizing the airflow from the fan motor. This advantageously improves the heat dissipation of the heat-generating components in the circuit unit.

[0013] (3) In the above (2), it is preferable that the heat-generating component includes a second heat-generating component disposed upstream of the fan motor in the airflow direction, and that the heat generation amount of the second heat-generating component is smaller than the heat generation amount of the first heat-generating component. Due to requirements such as space and circuit configuration within the battery pack, it may not be possible to place the fan motor at an end of the circuit unit. Even in such a case, by arranging the second heat-generating component, which generates a smaller heat generation amount than the first heat-generating component, upstream of the fan motor in the airflow direction, the conditions on the intake side of the fan motor can be satisfactorily met, while the first heat-generating component, which generates a larger heat generation amount, can be efficiently dissipated by utilizing the airflow from the fan motor.

[0014] (4) In any one of (1) to (3) above, it is preferable that the heat-generating component is disposed downstream of the fan motor in the airflow direction, and not upstream of the fan motor. By disposing the heat-generating component downstream of the fan motor, but not upstream, it is possible to prevent problems such as the temperature of the intake side of the fan motor rising due to the heat-generating component and exceeding the upper operating temperature limit of the fan motor.

[0015] (5) In the above (2) or (3), it is preferable that the first heat-generating component is a relay, the heat sink includes a plurality of heat sink plates protruding from the terminal portion, and the protruding height of the heat sink plates from the terminal portion is greater than the protruding height of the insulating partition plate protruding from the terminal portion of the relay. Since the protruding height of the heat sink's heat sink plates from the terminal portion is greater than the protruding height of the insulating partition plate protruding from the terminal portion of the relay, it is possible to prevent a problem in which the air blown from the fan motor is blocked by the insulating partition plate and does not reach the heat sink located downstream of the insulating partition plate in the air blowing direction. As a result, all of the plurality of heat sink's heat sink's heat sink plates can be dissipated by the air blown by the fan motor, thereby further improving the heat dissipation efficiency of the circuit unit.

[0016] (6) In any one of (1) to (5) above, it is preferable that the circuit unit further includes an airflow path extending downstream from the fan motor in the airflow direction of the fan motor, the heat-generating component being disposed within the airflow path, and the airflow path includes a partition plate disposed within the case to separate the interior space of the case. The airflow path extends downstream from the fan motor in the airflow direction of the fan motor, and the heat-generating component is disposed within the airflow path. This allows the airflow from the fan motor to be stably directed toward the downstream heat-generating component. Furthermore, since the airflow path includes a partition plate that separates the interior space of the case, the airflow path can be configured to be separated from other areas within the case, allowing the airflow from the fan motor to be efficiently directed toward the heat-generating component within the airflow path. As a result, the heat dissipation efficiency of the circuit unit can be further improved.

[0017] (7) In (6) when citing any one of (2), (3), and (5) above, it is preferable that the upstream opening of the airflow path is large enough to surround the fan motor, and the downstream opening of the airflow path is large enough to surround the heat sink or the first heat-generating component including the heat sink. The airflow path surrounds the fan motor at its upstream opening and surrounds the heat sink or the first heat-generating component including the heat sink at its downstream opening. This allows the airflow from the fan motor to be stably directed to the entire heat sink or the entire first heat-generating component including the heat sink, further improving the heat dissipation performance of the circuit unit. In particular, by using the airflow path of this aspect, the entire heat sink can be reliably cooled by the airflow from the fan motor, even if the heat sink is larger than the fan motor.

[0018] (8) In any one of (2), (3), (5), and (7) above, it is preferable that the fan motor includes an airflow path extending from the fan motor toward the downstream side in the airflow direction of the fan motor, the heat-generating component is disposed within the airflow path, and the cross-sectional area of ​​the airflow path in a direction perpendicular to the airflow direction is constant in a region of the airflow path from the fan motor to the heat sink. The airflow path extends in the airflow direction of the fan motor and downstream from the fan motor, and the heat-generating component is disposed within the airflow path. This allows the airflow from the fan motor to be stably guided toward the downstream heat-generating component. Furthermore, by keeping the cross-sectional area of ​​the airflow path perpendicular to the airflow direction constant in the region from the fan motor to the heat sink, the airflow from the fan motor can be efficiently guided to the heat sink while suppressing loss, thereby further improving the heat dissipation performance of the circuit unit.

[0019] (9) In any one of (1) to (8) above, it is preferable that the fan motor includes an airflow path extending from the fan motor toward the downstream side in the airflow direction of the fan motor, the heat-generating component includes a relay having a coil housed in a case body, and the airflow path includes a body cooling path that blows air onto a surface of the case body of the relay. If the heat-generating component is a relay, including the body cooling path in the airflow path can cool the heat generated by the coil with airflow, and more effectively promote heat dissipation from the heat-generating component, which is the relay, by utilizing the airflow from the fan motor.

[0020] (10) In any one of (1) to (9) above, it is preferable that the intake hole of the case includes a plurality of intake slits penetrating the case, the exhaust hole of the case includes a plurality of exhaust slits penetrating the case, the total cross-sectional area of ​​the plurality of intake slits is equal to or greater than the cross-sectional area perpendicular to the axis of the fan motor, and the total cross-sectional area of ​​the plurality of exhaust slits is equal to or greater than the cross-sectional area perpendicular to the axis of the fan motor. This is because by making the total cross-sectional area of ​​the plurality of intake slits constituting the intake hole and the plurality of exhaust slits constituting the exhaust hole provided in the case equal to or greater than the cross-sectional area perpendicular to the axis of the fan motor, the fan motor can smoothly circulate air within the case.

[0021] (11) In (10) when any one of (2), (3), (5), (7), and (8) above is cited, it is preferable that the heat sink includes a plurality of heat sink plates arranged in parallel, and at least one of the exhaust slits is arranged opposite a gap between the heat sink plates. This is because air can be smoothly blown from the gap between the plurality of heat sink plates constituting the heat sink to the exhaust slit, and the heat dissipation performance of the heat sink and, ultimately, the heat-generating components due to the air blown by the fan motor can be more reliably improved.

[0022] (12) In any one of the above (2), (3), (5), (7), (8), and (11), it is preferable that the heat sink is integrally provided on the head of a bolt fastened to the terminal portion of the first heat-generating component. This is because, when a bolt for fastening, for example, a current-carrying bus bar or the like is fastened to the terminal portion of the first heat-generating component, providing the heat sink integrally on the bolt reduces the number of parts and the number of work steps.

[0023] The circuit unit arrangement structure of the present disclosure is (13) a pair of circuit units described in any one of (1) to (12) above are arranged inside the battery pack as a positive electrode circuit unit and a negative electrode circuit unit, the air intake hole of the positive electrode circuit unit and the air intake hole of the negative electrode circuit unit are arranged in a central region inside the battery pack, separated from each other by an air intake gap, and the exhaust hole of the positive electrode circuit unit and the exhaust hole of the negative electrode circuit unit are arranged in a peripheral region inside the battery pack.

[0024] According to the circuit unit arrangement structure of this aspect, when a pair of circuit units each equipped with a fan motor is used for the positive and negative poles, smooth air intake is ensured inside the battery pack, while exhaust air heated by the heat-generating components is exhausted to the peripheral area and then moved to the center where it is sufficiently cooled before being drawn in again, thereby ensuring stable operation of the circuit units equipped with fan motors housed inside the battery pack.

[0025] The present disclosure can also be considered as the following other aspects that can improve the heat dissipation of a circuit unit. For example, each of the above aspects (6), (7), (8), (9), and (10) does not necessarily have to include the exhaust direction restriction unit of aspect (1), and can be adopted in combination with a circuit unit that includes a circuit configuration including a heat-generating component, a fan motor, a case that houses the circuit configuration and the fan motor, an intake hole provided in the case on the upstream side of the fan motor in the airflow direction, and an exhaust hole provided in the case on the downstream side of the fan motor in the airflow direction, thereby improving the heat dissipation of the circuit unit.

[0026] <Details of Embodiments of the Present Disclosure> Specific examples of circuit units and circuit unit arrangement structures of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0027] First Embodiment A circuit unit 10 and a circuit unit arrangement structure 11 according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 14 . The circuit unit 10 is mounted inside a battery pack 12 in an electric vehicle or a hybrid vehicle and prevents air heated by a heat-generating component 14 provided inside the circuit unit 10 from adversely affecting the battery modules 16 in the battery pack 12. In particular, in the first embodiment, a pair of circuit units 10 (a positive-side circuit unit 10 a and a negative-side circuit unit 10 b described below) are arranged inside the battery pack 12 using a specific circuit unit arrangement structure 11. Note that the battery pack 12 can be arranged in any orientation within the vehicle. However, in the following description, the upper side will be referred to as the front side in the direction perpendicular to the plane of the page in FIG. 2 (upper side in FIG. 6 ), the lower side will be referred to as the rear side in the direction perpendicular to the plane of the page in FIG. 2 (lower side in FIG. 6 ), the left side will be referred to as the left side in FIG. 2 , the right side will be referred to as the right side in FIG. 2 , the front side will be referred to as the lower side in FIG. 2 , and the rear side will be referred to as the upper side in FIG. 2 . Furthermore, in the case of multiple identical components, reference numerals may be assigned to only some of the components, and the reference numerals may be omitted for the other components.

[0028] <Battery Pack 12> The battery pack 12 is configured by housing a battery module 16 including a plurality of battery cells (single cells) 18 in a housing 20. In the first embodiment, each battery cell 18 has a substantially rectangular parallelepiped shape and is arranged such that the left-right dimension is greater than the front-rear dimension. The battery cells 18 are arranged in parallel at a predetermined distance in the front-rear and left-right directions, and are electrically connected by, for example, a bus bar module (not shown) extending in the front-rear direction. The battery cells 18 may be electrically connected in series or in parallel by the bus bar module. The battery module 16 is configured by connecting the battery cells 18 by the bus bar module.

[0029] A BMS (Battery Management System) board 22 is housed in a case and placed on the top surface of at least one of the battery cells 18. This BMS board 22 is electrically connected via wires (not shown) to a bus bar module that electrically connects the battery cells 18. A known board may be used as the BMS board 22, and has functions such as eliminating voltage differences between the battery cells 18 connected in series within the battery module 16 to balance them, and measuring the voltage, current, temperature, etc. of each battery cell 18 to monitor for abnormalities.

[0030] The housing 20 has an overall hollow rectangular box shape and is composed of a housing main body 24 that opens upward and a lid 28 that covers an upper opening 26 of the housing main body 24. The housing 20 is made of metal, for example, aluminum or an aluminum alloy. The method of fastening the housing main body 24 and the lid 28 is not limited, but they are fastened with bolts, screws, or the like. In the first embodiment, when the battery module 16 is housed in the housing main body 24, a gap is provided between the battery module 16 and the front wall of the housing main body 24, and the circuit unit 10 is mounted between the battery module 16 and the front wall of the housing main body 24.

[0031] In particular, in the first embodiment, an exhaust direction restricting portion 40 (described later) in the circuit unit 10 is formed integrally with the housing body 24, and the exhaust direction restricting portion 40 is formed to protrude inward in the left-right direction from the wall portions on both the left and right sides of the housing body 24. The exhaust direction restricting portion 40 has a triangular shape in a plan view (viewed from the up-down direction), and the front end surface is configured as an inclined surface 42 that is inclined with respect to the left-right and front-rear directions.

[0032] <Circuit Unit 10> The circuit unit 10 includes a circuit unit main body 29. The circuit unit main body 29 includes a circuit configuration section 30 including the heat-generating component 14, a fan motor 32, and a case 34 that houses the circuit configuration section 30 and the fan motor 32. The case 34 has an intake hole 36 on the upstream side of the fan motor 32 in the airflow direction, and an exhaust hole 38 on the downstream side of the fan motor 32 in the airflow direction. The circuit unit 10 also includes an exhaust direction restricting section 40 that directs exhaust air from the exhaust hole 38 away from the battery module 16. As described above, in the first embodiment, the exhaust direction restricting section 40 is formed integrally with the housing main body 24 of the battery pack 12 and is formed separately from the circuit unit main body 29. In short, in the first embodiment, the circuit unit 10 includes the circuit unit main body 29 and the exhaust direction restricting section 40.

[0033] In particular, in the first embodiment, a pair of circuit units 10, 10 is provided, including a positive circuit unit 10a electrically connected to the positive electrode of the battery module 16 (bus bar module connecting each battery cell 18) via an electric wire or the like (not shown), and a negative circuit unit 10b electrically connected to the negative electrode of the battery module 16 (bus bar module connecting each battery cell 18) via an electric wire or the like (not shown). The positive circuit unit 10a is provided on the left side of the battery pack 12, and the negative circuit unit 10b is provided on the right side of the battery pack 12.

[0034] The positive circuit unit 10a is configured to include a positive main body 29a and a positive restriction portion 40a, and the negative circuit unit 10b is configured to include a negative main body 29b and a negative restriction portion 40b. The positive restriction portion 40a is provided on the left wall of the housing main body 24, and the negative restriction portion 40b is provided on the right wall of the housing main body 24. The positive main body 29a and the negative main body 29b are each cuboid-shaped and are arranged inside the housing main body 24 so as to extend in the left-right direction.

[0035] 3 to 9 show the positive pole main body 29a constituting the positive pole circuit unit 10a. The positive pole main body 29a includes a positive pole circuit configuration section 30a, a positive pole fan motor 32a, and a positive pole case 34a. The positive pole circuit configuration section 30a includes a heat-generating component 14, which includes a relay 44 as a first heat-generating component and a fuse 46 as a second heat-generating component.

[0036] <Heat-Generating Component 14 (Relays 44 and Fuse 46)> In the first embodiment, the first heat-generating component is a relay 44. Two relays 44, 44, are provided in the left portion of the positive-electrode main body 29a, spaced apart from each other in the left-right direction. Each relay 44 includes a case body 48 shaped like a substantially hollow rectangular box. A pair of terminals 50, 50 are exposed from the case body 48 on the front side of each relay 44 (the front side of the right relay 44 and the rear side of the left relay 44), spaced apart from each other in the left-right direction. Furthermore, insulating partition plates 52 are provided on the surface of the case body 48 around each terminal 50, specifically between the terminals 50, to separate the terminals 50. Each insulating partition plate 52 protrudes from each terminal 50 toward the front side of the relay 44 by a protrusion height A (see FIG. 7 ). The case body 48 of each relay 44 also houses a coil 54, which is shown by the two-dot chain line in FIGS.

[0037] A heat sink 56 is thermally connected to each terminal portion 50 of each relay 44. In the first embodiment, two heat sinks 56, 56 are provided contiguously in the left-right direction. As shown in FIG. 5 , each heat sink 56 is generally rectangular in plan view, and each heat sink 56 has a plate-like portion 58 extending horizontally (perpendicular to the up-down direction) at its lower end. Each heat sink 56 has a plurality of heat sink plates 60 protruding upward from the plate-like portion 58. The heat sinks 60 are arranged in parallel and spaced apart from each other in the front-to-rear direction, extending in the left-to-right direction. This provides gaps 62 extending in the left-to-right direction between the heat sinks 60 in the front-to-rear direction. In the first embodiment, the front-to-rear dimensions of each gap 62 are generally equal, and the front-to-rear dimension of each gap 62 is designated B (see FIG. 7 ).

[0038] The front-to-rear width of each heat sink 56 is larger than the front-to-rear width of the positive pole fan motor 32a, and the positive pole fan motor 32a and the heat sink 56 are connected by an exhaust duct 92 (described later). The front-to-rear width of the exhaust duct 92 increases toward the left, and the right end of the exhaust duct 92 has approximately the same front-to-rear width as the positive pole fan motor 32a, while the left end of the exhaust duct 92 has approximately the same front-to-rear width as the heat sink 56. This allows the air blown from the positive pole fan motor 32a to reach the entire front-to-rear of each heat sink 56.

[0039] 7, the terminal portion 50 of each relay 44 is connected to the later-described current-carrying bus bars 72d to 72g that constitute the positive-pole circuit configuration portion 30a by bolts 64. These current-carrying bus bars 72d to 72g extend upward from the fixed portion with each terminal portion 50 and then bend inward in the front-to-rear direction to cover the top of each relay 44, and each heat sink 56 is fixed via an insulating heat-conductive sheet 66 to the portion 72a of each current-carrying bus bar 72d to 72g that covers the top of each relay 44.

[0040] Each insulating thermally conductive sheet 66 is a sheet-like member having electrical insulation and good thermal conductivity, and known insulating thermally conductive sheets may be used. The insulating thermally conductive sheets 66 may be, for example, grease-like or gel-like, and may be applied to a predetermined location and then cured by heat, light (ultraviolet light), or the like. The portions 72a of each of the current-carrying bus bars 72d-72g that cover the relays 44 and the heat sink 56 may be fixed via the insulating thermally conductive sheets 66 with adhesive, bolts, or both adhesive and bolts. This fixes each relay 44 and each heat sink 56 via the current-carrying bus bars 72d-72g and the insulating thermally conductive sheets 66, and thermally connects each heat sink 56 to each terminal portion 50.

[0041] In the first embodiment, the second heat-generating component is a fuse 46, which is provided on the front side of the right portion of the positive electrode main body 29a. A pre-charge relay 68 and a pre-charge resistor 70 are provided on the rear side of the right portion of the positive electrode main body 29a. The fuse 46 generates less heat when energized than the relays 44, i.e., the second heat-generating component (fuse 46) generates less heat than the first heat-generating components (relays 44). The pre-charge relay 68 and the pre-charge resistor 70 may be included as the second heat-generating component in addition to the fuse 46. Because the pre-charge relay 68 and the pre-charge resistor 70 generate relatively little heat when energized, even if the pre-charge relay 68 and the pre-charge resistor 70 are included as the second heat-generating component, the heat generation of each of the second heat-generating components is smaller than that of the first heat-generating component.

[0042] <Circuit Configuration Unit 30 (Positive Pole Circuit Configuration Unit 30a)> The relays 44 and fuses 46 are electrically connected by a plurality of energizing bus bars 72. That is, the energizing bus bars 72 are overlapped with a pair of terminals 74, 74 of the fuse 46 and with each terminal 50 of each relay 44, and are fixed by bolts 76 (one is shown in FIG. 6 ). Specifically, an energizing bus bar 72b is fixed to the right terminal 74 of the fuse 46, and the left terminal 74 of the fuse 46 is connected to the right terminal 50 of the right relay 44 by energizing bus bars 72c, 72d. The left terminal 50 of the right relay 44 is connected to the right terminal 50 of the left relay 44 by an energizing bus bar 72e, and an energizing bus bar 72f is fixed to the left terminal 50 of the left relay 44. Furthermore, a separate energizing bus bar 72g, which is separate from the energizing bus bar 72e, is superimposed on and fixed to the left terminal portion 50 of the right relay 44, and extends out to the left.

[0043] As a result, an external connection portion 78 is formed at the right end of the positive electrode main body 29a by the end of the current-carrying bus bar 72b, and external connection portions 80 are formed at the left end of the positive electrode main body 29a by the ends of the current-carrying bus bars 72f, 72g. Terminal portions provided on the ends of external electric wires (not shown) are overlapped with these external connection portions 78, 80 and fixed with bolts or the like, thereby electrically connecting each of the current-carrying bus bars 72b to 72g and each of the relays 44 and fuses 46 to the external electric wires. While not limited thereto, for example, the external connection portion 78 is connected to the battery module 16 (particularly the bus bar module) to serve as a connection portion for inputting power to the positive electrode main body 29a, and each of the external connection portions 80 is connected to external electrical devices to serve as a connection portion for outputting power to the external electrical devices.

[0044] The precharge relay 68 and the precharge resistor 70 are, for example, electrically connected in series to form a precharge circuit that bypasses the right-side relay 44 by means of an electric wire or the like (not shown). That is, the terminal portions of the precharge relay 68 and the precharge resistor 70 on the side opposite to the side where they are connected to each other are connected by an electric wire or the like to, for example, the current-carrying bus bars 72d, 72e.

[0045] In embodiment 1, the positive pole circuit configuration section 30a in the positive pole main body 29a is configured to include each relay 44, which is a first heat-generating component, a fuse 46, which is a second heat-generating component, a pre-charge relay 68, a pre-charge resistor 70, and each current-carrying bus bar 72b to 72g.

[0046] In particular, in the first embodiment, a plurality of heat dissipation bus bars 82 are fixed at the fixed locations between the terminals 74 of the fuse 46 and the current-carrying bus bars 72b, 72c, and at the fixed locations between the terminals 50 of the relays 44 and the current-carrying bus bars 72d to 72g. Each heat dissipation bus bar 82 is generally L-shaped and has a heat dissipation portion 84 extending horizontally and a portion protruding upward from the heat dissipation portion 84. The upward-protruding portion of each heat dissipation bus bar 82 is fastened together with the current-carrying bus bars 72b to 72g to the terminals 74 of the fuse 46 and the terminals 50 of the relays 44 by bolts 76, 64. When assembling the positive electrode main body 29a, the heat dissipation portion 84 of each heat dissipation bus bar 82 is overlapped with a positive electrode lower case 100 (described later) constituting the case 34 (positive electrode case 34a) via an insulating heat-conductive sheet 86. The insulating heat conductive sheet 86 may be the same as the insulating heat conductive sheet 66 described above.

[0047] <Fan Motor 32 (Positive Pole Fan Motor 32a)> A known fan motor may be used as the positive pole fan motor 32a. An internal blade (not shown) rotates around a central axis L, generating an airflow from one axial direction of the positive pole fan motor 32a to the other. In the first embodiment, the airflow is generated from right to left in the positive pole main body 29a. The airflow (airflow direction α) generated by the positive pole fan motor 32a in the positive pole main body 29a is indicated by a two-dot chain line in FIG. 2. As shown in FIG. 5, the central axis L of the positive pole fan motor 32a is located at the center of each heat sink 56 in the front-to-rear direction in a plan view.

[0048] In the first embodiment, the positive pole fan motor 32a is disposed in the positive pole main body 29a between the first heat-generating components (relays 44) and the second heat-generating components (fuse 46, precharge relay 68, and precharge resistor 70). That is, the first heat-generating components (relays 44) are disposed on the left side of the positive pole fan motor 32a, and the second heat-generating components (fuse 46, precharge relay 68, and precharge resistor 70) are disposed on the right side of the positive pole fan motor 32a. In other words, in the first embodiment, the first heat-generating components (relays 44) and the heat sinks 56 fixed above the relays 44 are disposed downstream of the positive pole fan motor 32a in the airflow direction α. ​​Furthermore, the second heat-generating components (fuse 46, precharge relay 68, and precharge resistor 70) are disposed upstream of the positive pole fan motor 32a in the airflow direction α.

[0049] Specifically, in the positive pole main body 29a, the space extending downstream from the positive pole fan motor 32a is an air flow path 88 (shown by a two-dot chain line in FIG. 7) where airflow is generated as the blades of the positive pole fan motor 32a rotate. On the other hand, in the positive pole main body 29a, the space upstream of the positive pole fan motor 32a is a suction path 90 (shown by a two-dot chain line in FIG. 6) where airflow is generated in a direction in which air is sucked toward the positive pole fan motor 32a as air is blown by the positive pole fan motor 32a.

[0050] In particular, in the first embodiment, as shown in Figures 4 and 8, the central axis L of the positive pole fan motor 32a is inclined relative to the left-right direction, inclining upward as it moves to the left. An exhaust duct 92 is provided adjacent to the positive pole fan motor 32a on the downstream side (left side) of the positive pole fan motor 32a in the airflow direction α, and the exhaust duct 92 is continuous with the heat sink 56 on the right. The exhaust duct 92 has a bottom wall portion continuous with the plate-shaped portion 58 of each heat sink 56 and a pair of side walls 94, 94 provided on both sides of the bottom wall in the front-to-rear direction, the distance between them gradually increasing toward the left. The distance between each side wall 94 in the front-to-rear direction is approximately equal to that of the positive pole fan motor 32a at the right end and approximately equal to that of each heat sink 56 at the left end. As a result, the air blown by the positive pole fan motor 32a is applied to the entire front-to-back direction of each heat sink 56 through the area surrounded by the exhaust duct 92 and the positive pole upper case 98 (described later) in the positive pole case 34a.

[0051] The above-described air supply path 88 and suction path 90 are regions surrounded by, for example, the positive pole case 34a (a positive pole upper case 98 and a positive pole lower case 100, which will be described later). In the first embodiment, as described above, the central axis L of the positive pole fan motor 32a is inclined upward toward the left, and the space downstream of the positive pole fan motor 32a is partitioned in the vertical direction by the bottom wall of the exhaust duct 92 and the plate-like portions 58 of each heat sink 56. As a result, the air supply path 88 is particularly defined by the space above the positive pole case 34a downstream of the positive pole fan motor 32a (the portion above the bottom wall of the exhaust duct 92 and the plate-like portions 58 of each heat sink 56). In addition, the lower space downstream of the positive pole fan motor 32a is connected to the upper space, and although the airflow speed is slower than in the upper part, the air in the upper part and the air in the lower part flow together, so almost the entire space downstream of the positive pole fan motor 32a can be considered to be the air supply path 88.

[0052] The positive pole fan motor 32a, with its multiple blades (not shown) housed in a case, is fixed to a support frame 96, for example, by bolts. The support frame 96 is then fixed to a positive pole lower case 100 (described later) of the positive pole case 34a, for example, by bolts, so that the positive pole fan motor 32a is fixed to the positive pole circuit component 30a via the positive pole case 34a. The support frame 96 supporting the positive pole fan motor 32a and the exhaust duct 92 may be fixed by known fixing means, such as welding, adhesive, or recess-and-projection fitting. The exhaust duct 92 and the right-side heat sink 56 may also be fixed by known fixing means, such as welding, adhesive, or recess-and-projection fitting.

[0053] <Case 34 (Positive Electrode Case 34a)> The positive electrode case 34a is a hollow rectangular parallelepiped overall, and includes a positive electrode upper case 98 and a positive electrode lower case 100 that can be assembled and disassembled relative to each other in the vertical direction. The positive electrode upper case 98 and the positive electrode lower case 100 are formed from, for example, synthetic resin.

[0054] <Positive Electrode Upper Case 98> The positive electrode upper case 98 is generally box-shaped and opens downward. It includes an upper bottom wall 102 and an upper peripheral wall 104 that protrudes downward from the outer periphery of the upper bottom wall 102. Specifically, the upper peripheral wall 104 includes an upper front wall 104a that forms the front wall, an upper rear wall 104b that forms the rear wall, an upper left wall 104c that forms the left wall, and an upper right wall 104d that forms the right wall. The positive electrode upper case 98 is formed with a larger left-right dimension than a front-to-rear dimension. The left portion of the positive electrode upper case 98 has a larger vertical dimension than the right portion, allowing the positive electrode circuit component 30a, the positive electrode fan motor 32a, the heat sinks 56, and the like to be stably housed in the positive electrode upper case 98.

[0055] As described above, the case 34 has an intake hole 36 on the upstream side of the airflow direction of the fan motor 32, and an exhaust hole 38 on the downstream side of the airflow direction of the fan motor 32. Therefore, the positive pole case 34a has a positive pole intake hole 36a on the right side, which is upstream of the airflow direction α of the positive pole fan motor 32a, and a positive pole exhaust hole 38a on the left side, which is downstream of the airflow direction α of the positive pole fan motor 32a. In the first embodiment, these positive pole intake hole and exhaust holes 36a, 38a are both provided in the positive pole upper case 98. Furthermore, the suction path 90 in the positive pole case 34a is in communication with the outside space through the positive pole intake hole 36a, and the airflow path 88 in the positive pole case 34a is in communication with the outside space through the positive pole exhaust hole 38a.

[0056] In particular, in the first embodiment, the positive electrode air intake hole 36a is configured to include a plurality of air intake slits 106. These air intake slits 106 are formed in the right portions of the upper bottom wall 102, the upper front wall 104a, and the upper rear wall 104b, and in the upper right wall 104d, penetrating each wall in the thickness direction. The air intake slits 106 are aligned in the front-rear and / or left-right directions in each of these wall portions.

[0057] Similarly, in the first embodiment, the positive electrode exhaust hole 38a is configured to include a plurality of exhaust slits 108. These exhaust slits 108 are formed in the left portions of the upper bottom wall 102, the upper front wall 104a, and the upper rear wall 104b, and in the upper left wall 104c, penetrating each wall in the thickness direction. The exhaust slits 108 are aligned in the front-rear and / or left-right directions in each of these wall portions.

[0058] Although the size of each intake slit 106 and each exhaust slit 108 is not limited, it is preferable that the total cross-sectional area of ​​the intake slits 106 be equal to or greater than the axial cross-sectional area (cross-sectional area perpendicular to the central axis L) of the positive pole fan motor 32a. The total cross-sectional area of ​​the intake slits 106 refers to the total cross-sectional area in the thickness direction of the upper bottom wall 102, upper front wall 104a, upper rear wall 104b, and upper right wall 104d in which the intake slits 106 are provided. Similarly, it is preferable that the total cross-sectional area of ​​the exhaust slits 108 be equal to or greater than the axial cross-sectional area of ​​the positive pole fan motor 32a. The total cross-sectional area of ​​the exhaust slits 108 refers to the total cross-sectional area in the thickness direction of the upper bottom wall 102, upper front wall 104a, upper rear wall 104b, and upper left wall 104c in which the exhaust slits 108 are provided. Specifically, the opening width dimension C (see FIG. 7) of the exhaust slit 108 is preferably set to, for example, 3 mm or more. Similarly, the opening width dimension of the intake slit 106 is preferably set to, for example, 3 mm or more.

[0059] 7 , it is preferable that at least one of the plurality of exhaust slits 108 be provided at approximately the same position in the front-to-rear direction as the gaps 62 between the heat sinks 60, 60 provided in each heat sink 56, and be opposed in the left-to-right direction. In the first embodiment, some of the plurality of exhaust slits 108 are opposed in the left-to-right direction to some of the gaps 62 between the heat sinks 60, 60. Similarly, it is preferable that at least one of the plurality of intake slits 106 be provided at approximately the same position in the front-to-rear direction as the gaps 62 between the heat sinks 60, 60 provided in each heat sink 56.

[0060] In the first embodiment, a plurality of locking recesses 110, which engage with locking protrusions 122 (described later) of the positive electrode lower case 100, are provided at the lower end of each wall portion (upper front wall portion 104a, upper rear wall portion 104b, upper left wall portion 104c, and upper right wall portion 104d) constituting the upper peripheral wall portion 104 and are spaced apart in the circumferential direction. Furthermore, in the positive electrode case 34a, an electric wire insertion hole 112 through which an external electric wire connected to the external connection portion 78 is inserted is formed at a position corresponding to the external connection portion 78, and electric wire insertion holes 114 through which an external electric wire connected to each external connection portion 80 is inserted are formed at positions corresponding to each external connection portion 80. In the first embodiment, an upper insertion hole 112a constituting the wire insertion hole 112 is formed in the right end portion of the upper rear wall portion 104b, and upper insertion holes 114a constituting the wire insertion hole 114 are formed in the left end portions of the upper front wall portion 104a and the upper rear wall portion 104b. These upper insertion holes 112a, 114a, together with lower insertion holes 112b, 114b (described later) provided in the positive electrode lower case 100, respectively, constitute the wire insertion holes 112, 114.

[0061] <Positive electrode lower case 100> The positive electrode lower case 100 has a generally box-like shape that opens upward. It includes a bottom wall 116 and a lower peripheral wall 118 that protrudes upward from the outer periphery of the bottom wall 116. The positive electrode lower case 100 is formed with a larger left-right dimension than its front-to-rear dimension. When the positive electrode upper case 98 and the positive electrode lower case 100 are assembled, the open end of the lower peripheral wall 118 and the open end of the upper peripheral wall 104 are butted together in the vertical direction, so that the upper opening of the lower peripheral wall 118 is covered by the positive electrode upper case 98. The positive electrode lower case 100 also holds multiple nuts 120 in a generally embedded state. Each nut 120 is designed to be fastened by the aforementioned bolt 76, or by bolts (not shown) that are inserted through the support frame 96 supporting the positive electrode fan motor 32a and the external connection parts 78 and 80.

[0062] In the first embodiment, locking protrusions 122 that protrude outward are formed at the upper end of the lower peripheral wall portion 118 at positions corresponding to the locking recesses 110 in the positive-electrode upper case 98. Furthermore, lower insertion holes 112b that constitute the wire insertion holes 112 are formed in the lower peripheral wall portion 118 at positions corresponding to the external connection portions 78, and lower insertion holes 114b that constitute the wire insertion holes 114 are formed in positions corresponding to the external connection portions 80. In the first embodiment, the lower insertion hole 112b is formed in the right end portion of the rear wall portion of the lower peripheral wall portion 118, and the lower insertion holes 114b are formed in the left end portions of the front and rear wall portions of the lower peripheral wall portion 118.

[0063] <Negative electrode circuit unit 10b> The negative electrode main body 29b constituting the negative electrode circuit unit 10b is shown in Figures 10 to 14. The negative electrode main body 29b includes a negative electrode circuit configuration section 30b, a negative electrode fan motor 32b, and a negative electrode case 34b. The basic structure of the negative electrode main body 29b is similar to that of the positive electrode main body 29a, and only a brief explanation of the negative electrode main body 29b will be given. In the figures, components and parts of the negative electrode main body 29b that are substantially the same as those of the positive electrode main body 29a are designated by the same reference numerals as those of the positive electrode main body 29a.

[0064] The negative-electrode circuit configuration unit 30b also includes a relay 44 as a first heat-generating component and a fuse 46 as a second heat-generating component as heat-generating components 14. In the first embodiment, two relays 44, 44 are provided spaced apart from each other in the left-right direction in the right portion of the negative-electrode main body 29b. Each relay 44 includes a case body 48, and a pair of terminals 50, 50 are provided on the front side of each relay 44 (the front side of the right relay 44 and the rear side of the left relay 44). An insulating partition plate 52 is provided between the terminals 50 and extends over the entire vertical length of each relay 44. The case body 48 of each relay 44 houses a coil 54, shown by a two-dot chain line in FIG. 14 .

[0065] Furthermore, a heat sink 56 is thermally connected to each terminal portion 50 of each relay 44. The heat sinks 56 are provided at approximately the same position in the front-to-rear direction and are spaced apart from each other in the left-to-right direction. Current-carrying bus bars 72d to 72g are connected to each terminal portion 50 of each relay 44 with bolts 64, and each relay 44 and each heat sink 56 are fixed via each current-carrying bus bar 72d to 72g and each insulating heat-conducting sheet 66. As a result, heat generated by each relay 44 is transferred to each heat sink 56 via each current-carrying bus bar 72d to 72g and each insulating heat-conducting sheet 66.

[0066] A fuse 46 is provided in the left portion of the negative electrode main body 29b. The fuse 46 in the negative electrode main body 29b may be, for example, a pyro fuse. A monitoring and driving unit 124 is provided in the right portion of the negative electrode main body 29b. The monitoring and driving unit 124 is configured, for example, by housing a board or the like on which a microcomputer or the like (not shown) is mounted in a case, and monitors the internal condition of the negative electrode main body 29b and drives the positive electrode and negative electrode fan motors 32a, 32b as necessary.

[0067] That is, in the first embodiment, the monitoring and driving unit 124 includes a temperature sensor (not shown) and is electrically connected to the positive pole fan motor 32a and the negative pole fan motor 32b via wires (not shown). The monitoring and driving unit 124 monitors the temperature inside the negative pole main body 29b or the battery pack 12, and when the temperature exceeds a predetermined temperature, it sends a driving signal to the positive pole fan motor 32a or the negative pole fan motor 32b to drive the positive pole and negative pole fan motors 32a, 32b. Note that the monitoring and driving unit 124 may be configured to monitor, for example, the current flowing through the negative pole main body 29b and to send a driving signal to the positive pole fan motor 32a or the negative pole fan motor 32b when a current greater than a predetermined value flows. Therefore, the monitoring and driving unit 124 may be electrically connected to, for example, the current busbar 72 (current busbars 72b to 72g) in the negative pole main body 29b.

[0068] Alternatively, the monitoring and driving unit 124 may be electrically connected to the aforementioned BMS board 22 provided within the battery pack 12, and when the BMS board 22 detects that the temperature or current (or voltage) within the battery pack 12 has exceeded a predetermined value, the BMS board 22 may send a signal to the monitoring and driving unit 124 to drive the positive pole fan motor 32a and the negative pole fan motor 32b.

[0069] <Circuit configuration unit 30 (negative electrode circuit configuration unit 30b)> In the first embodiment, the negative electrode circuit configuration unit 30b in the negative electrode main body 29b includes the relays 44 as first heat-generating components, the fuses 46 as second heat-generating components, the current-carrying bus bars 72b to 72g, and the monitoring and driving unit 124. Heat-dissipating bus bars 82 are fixed to the current-carrying bus bars 72b to 72g with bolts 64, 76. The heat-dissipating portions 84 of the heat-dissipating bus bars 82 are overlapped with a negative electrode lower case 128 (described later) that constitutes the case 34 (negative electrode case 34b) via insulating thermally conductive sheets 86.

[0070] <Fan Motor 32 (Negative Pole Fan Motor 32b)> The negative pole fan motor 32b may have the same shape as the positive pole fan motor 32a. In the first embodiment, the blades (not shown) of the negative pole fan motor 32b rotate around the central axis M, generating an airflow from left to right in the negative pole main body 29b. The airflow (airflow direction β) generated by the negative pole fan motor 32b in the negative pole main body 29b is indicated by a two-dot chain line in FIG. 2. As shown in FIG. 11, the central axis M of the negative pole fan motor 32b is located at the center of each heat sink 56 in the front-to-rear direction in a plan view.

[0071] The negative pole fan motor 32b is disposed in the negative pole main body 29b between the first heat-generating component (relays 44) and the second heat-generating component (fuse 46). In other words, in the first embodiment, the first heat-generating component (relays 44) and the heat sinks 56 fixed above the relays 44 are disposed downstream of the negative pole fan motor 32b in the airflow direction β. The second heat-generating component (fuse 46) is disposed upstream of the negative pole fan motor 32b in the airflow direction β. In other words, an airflow path 88 is formed in the space on the right side of the negative pole main body 29b, through which airflow is generated as the blades of the negative pole fan motor 32b rotate. A suction path 90 (shown by a two-dot chain line in FIG. 12 ) is formed in the space on the left side of the negative pole main body 29b, through which airflow is generated in a direction that draws air toward the negative pole fan motor 32b.

[0072] In particular, in the first embodiment, as shown in FIG. 12 , the negative pole fan motor 32b is provided in the vertically middle portion of the negative pole main body 29b. Therefore, the airflow from the negative pole fan motor 32b is distributed not only to the upper portion of the negative pole main body 29b (e.g., the area where the heat sinks 56 are located) but also to the lower portion of the negative pole main body 29b (e.g., the area where the relays 44 are located). Therefore, the airflow path 88 extends downstream of the negative pole fan motor 32b and covers substantially the entire area enclosed by the negative pole case 34b (the negative pole upper case 126 and the negative pole lower case 128, described below). Similarly, the suction path 90 extends upstream of the negative pole fan motor 32b and covers substantially the entire area enclosed by the negative pole case 34b. As a result, in the negative electrode main body 29b, the air supply path 88 and the suction path 90 are formed with approximately the same cross-sectional area (cross-sectional area in a cross section perpendicular to the left-right direction), allowing air to flow with approximately a constant cross-sectional area.

[0073] The negative pole fan motor 32b is fixed to the support frame 96 by, for example, bolts. The support frame 96 is then fixed to a negative pole upper case 126 (described later) of the negative pole case 34b by, for example, bolts, so that the negative pole fan motor 32b is fixed to the negative pole circuit configuration unit 30b via the negative pole case 34b.

[0074] <Case 34 (Negative Electrode Case 34b)> The negative electrode case 34b is a hollow rectangular parallelepiped as a whole, and is configured to include a negative electrode upper case 126 and a negative electrode lower case 128 that can be assembled and disassembled relative to each other in the vertical direction. The negative electrode upper case 126 and the negative electrode lower case 128 are formed from, for example, synthetic resin.

[0075] <Negative electrode upper case 126> The negative electrode upper case 126 has the same shape as the positive electrode upper case 98, and includes an upper bottom wall portion 102 and an upper peripheral wall portion 104 that protrudes downward from the outer peripheral edge of the upper bottom wall portion 102. The upper peripheral wall portion 104 includes an upper front wall portion 104a, an upper rear wall portion 104b, an upper left wall portion 104c, and an upper right wall portion 104d.

[0076] The negative electrode case 34b has a negative electrode intake hole 36b on the left side, which is upstream of the airflow direction β of the negative electrode fan motor 32b, and a negative electrode exhaust hole 38b on the right side, which is downstream of the airflow direction β of the negative electrode fan motor 32b. In the first embodiment, these negative electrode intake hole and exhaust holes 36b, 38b are all provided in the negative electrode upper case 126. That is, the suction path 90 in the negative electrode case 34b communicates with the outside space through the negative electrode intake hole 36b, and the air flow path 88 in the negative electrode case 34b communicates with the outside space through the negative electrode exhaust hole 38b.

[0077] The negative electrode air intake hole 36b includes a plurality of air intake slits 106. Each of the plurality of air intake slits 106 is formed at the left end of the upper bottom wall 102 and the upper left wall 104c, penetrating each wall in the thickness direction. The air intake slits 106 are provided in parallel at the left end of the negative electrode upper case 126 and spaced apart from each other in the front-to-rear direction.

[0078] Similarly, the negative electrode exhaust hole 38b is configured to include a plurality of exhaust slits 108. Each of these exhaust slits 108 is formed at the right end of the upper bottom wall portion 102 and the upper right wall portion 104d, penetrating each wall portion in the plate thickness direction. The exhaust slits 108 are provided in parallel at the right end of the negative electrode upper case 126, spaced apart from each other in the front-to-rear direction.

[0079] The size of the negative electrode intake and exhaust holes 36b, 38b provided in the negative electrode upper case 126 is not limited, but may be similar in size to the positive electrode intake and exhaust holes 36a, 38a provided in the positive electrode upper case 98. Furthermore, it is preferable that at least one of the multiple exhaust slits 108 be provided at approximately the same position in the front-to-rear direction as the gap 62 between the heat sinks 60, 60 provided in each heat sink 56 and be opposed in the left-to-right direction. Similarly, it is preferable that at least one of the multiple intake slits 106 be provided at approximately the same position in the front-to-rear direction as the gap 62 between the heat sinks 60, 60 provided in each heat sink 56.

[0080] <Negative electrode lower case 128> The negative electrode lower case 128 has a shape similar to that of the positive electrode lower case 100 and includes a bottom wall 116 and a lower peripheral wall 118 that protrudes upward from the outer periphery of the bottom wall 116. The negative electrode upper case 126 and the negative electrode lower case 128 may be fixed to each other by a protrusion-recessed engagement between a locking projection and a locking recess, as in the case of the positive electrode case 34a, or by other known fixing means. Similarly to the positive electrode case 34a, the negative electrode case 34b may have a wire insertion hole formed therein through which an external wire (not shown) is inserted. This wire insertion hole may be provided in the negative electrode upper case 126, or may be provided across both the negative electrode upper case 126 and the negative electrode lower case 128.

[0081] <Circuit unit arrangement structure 11> As described above, the circuit units 10 (positive and negative electrode circuit units 10a, 10b) are arranged in the front portion of the housing main body 24. Specifically, as also shown in Fig. 2, the exhaust direction restriction portions 40 (positive and negative electrode restriction portions 40a, 40b) described above are provided in the front portion of the housing main body 24, and the circuit unit main bodies 29 (positive and negative electrode main bodies 29a, 29b) are arranged between the exhaust direction restriction portions 40a, 40b and the front wall portion of the housing main body 24.

[0082] The positive electrode main body 29a and the negative electrode main body 29b are arranged so that their respective air intake holes 36 (positive electrode air intake hole 36a and negative electrode air intake hole 36b) face each other. The positive electrode air intake hole 36a of the positive electrode main body 29a and the negative electrode air intake hole 36b of the negative electrode main body 29b are separated from each other by an air intake gap 130 within the housing main body 24. The positive electrode and negative electrode air intake holes 36a, 36b are each arranged in a central region 132 in the left-right direction within the battery pack 12.

[0083] In contrast, the positive electrode main body 29a and the negative electrode main body 29b are arranged so that their respective exhaust holes 38 (positive electrode exhaust hole 38a and negative electrode exhaust hole 38b) face the wall portions on both the left and right sides of the housing main body 24. In other words, these positive electrode and negative electrode exhaust holes 38a, 38b are respectively arranged in peripheral regions 134, 134 on both the left and right sides inside the battery pack 12. This constitutes the circuit unit arrangement structure 11 according to the present disclosure.

[0084] <Assembly of Circuit Unit 10 (Positive and Negative Circuit Units 10a, 10b)> A specific example of a method for assembling each of the positive and negative circuit units 10a, 10b will be described below. Note that the assembly methods for the positive and negative circuit units 10a, 10b are not limited to the embodiments described below.

[0085] First, a method for assembling the positive pole main body 29a in the positive pole circuit unit 10a will be described. First, the relays 44 and fuses 46 are bolted to the positive pole lower case 100 along with the current-carrying bus bars 72b-72g and the heat-dissipating bus bars 82. Note that insulating and heat-conducting sheets 86 are provided in advance on the upper surface of the bottom wall 116 of the positive pole lower case 100 and / or the underside of the heat-dissipating portion 84 of each heat-dissipating bus bar 82. The positive pole fan motor 32a and the exhaust duct 92 are then secured to each other, and the positive pole fan motor 32a and the exhaust duct 92 are then bolted to the positive pole lower case 100. Next, the heat sinks 56 are placed over the portions 72a of the current-carrying bus bars 72d-72g that cover the relays 44, with the insulating and heat-conducting sheets 66 interposed therebetween, and secured with bolts or the like. Thereafter, the pre-charge relay 68 and the pre-charge resistor 70 are electrically connected to a predetermined current-carrying bus bar 72 .

[0086] Next, a method for assembling the negative-electrode main body 29b in the negative-electrode circuit unit 10b will be described. First, the relays 44 and fuses 46 are bolted to the negative-electrode lower case 128 along with the current-carrying bus bars 72b-72g and the heat-dissipating bus bars 82. Note that insulating and heat-conducting sheets 86 are provided in advance on the upper surface of the bottom wall portion 116 of the negative-electrode lower case 128 and / or the lower surface of the heat-dissipating portion 84 of each heat-dissipating bus bar 82. The heat sinks 56 are then superimposed on the portions 72a of the current-carrying bus bars 72d-72g that cover the relays 44 via the insulating and heat-conducting sheets 66, and secured with bolts or the like. Meanwhile, the negative-electrode fan motor 32b is secured to the negative-electrode upper case 126 via a support frame 96. Thereafter, the monitoring and driving unit 124 is housed in the negative pole lower case 128, and the monitoring and driving unit 124 is electrically connected to the positive pole and negative pole fan motors 32a, 32b.

[0087] Next, the positive upper case 98 is brought close from above to fix the positive upper case 98 and the positive lower case 100 together, thereby completing the positive main body 29a. The negative upper case 126 is brought close from above to fix the negative upper case 126 and the negative lower case 128 together, thereby completing the negative main body 29b. The positive and negative main bodies 29a, 29b are disposed in the housing main body 24, on which the positive and negative restricting portions 40a, 40b are provided, between the positive and negative restricting portions 40a, 40b and the front wall of the housing main body 24. As a result, the positive main body 29a and the positive restricting portion 40a form the positive circuit unit 10a, and the negative main body 29b and the negative restricting portion 40b form the negative circuit unit 10b.

[0088] In this manner, the battery pack 12 is configured by housing a plurality of battery cells 18 and a BMS board 22 in the housing main body 24, which has the positive and negative circuit units 10a, 10b provided therein, and electrically connecting these together. In this battery pack 12, for example, when the monitoring and driving unit 124 detects that the temperature inside the negative main body 29b exceeds a predetermined temperature, a fan driving signal is sent to the positive and negative fan motors 32a, 32b, driving these positive and negative fan motors 32a, 32b. Alternatively, when the BMS board 22 detects that the temperature inside the battery pack 12 exceeds a predetermined temperature, a signal for driving the positive and negative fan motors 32a, 32b is sent to the positive and negative fan motors 32a, 32b via the monitoring and driving unit 124, driving these positive and negative fan motors 32a, 32b.

[0089] For example, in the positive circuit unit 10a, when the positive fan motor 32a is driven, air is drawn in through the positive air intake 36a adjacent to the battery cells 18, generating an airflow in the airflow direction α, which is then exhausted through the positive exhaust 38a. The air exhausted through the positive exhaust 38a is redirected by the inclined surface 42 of the positive restriction portion 40a and flows in a direction (forward) away from the battery cells 18. The air redirected by the inclined surface 42 then flows inward (to the right) in the left-right direction between the positive main body 29a and the front wall of the housing main body 24, reaching the central region 132 in the left-right center. The air that reaches the central region 132 is again drawn in through the positive air intake 36a and circulates.

[0090] The positive circuit configuration section 30a in the positive main body 29a includes heat-generating components 14, such as relays 44 and fuses 46. These components, which generate heat when energized, are cooled by the air blown by the positive fan motor 32a. Air passing through the positive main body 29a increases in temperature upon contact with the relays 44 and fuses 46. However, the inclined surface 42 of the positive restriction section 40a redirects the heated air away from the battery cells 18. This prevents air heated by the heat-generating components 14 (such as the relays 44 and fuses 46) from flowing toward the battery modules 16 (the battery cells 18) and adversely affecting the battery modules 16. The air exhausted from the positive exhaust hole 38a can also be cooled by contacting the wall of the housing main body 24 of the battery pack 12, allowing the air exhausted from the positive exhaust hole 38a to be drawn in through the positive intake hole 36a at a lower temperature. This allows for efficient cooling of the heat generated in the heat-generating component 14. The above-mentioned effect can be similarly achieved in the negative electrode circuit unit 10b.

[0091] The heat-generating component 14 includes relays 44 as first heat-generating components, each having a heat sink 56 thermally connected to a terminal portion 50, and each relay 44 and each heat sink 56 are arranged downstream of each fan motor 32 (positive and negative pole fan motors 32a, 32b) in the airflow directions α and β. This allows the heat generated at the terminal portion 50 of each relay 44, which generates a relatively large amount of heat, to be dissipated by the air blown from the positive and negative pole fan motors 32a, 32b, using each heat sink 56.

[0092] The heat-generating component 14 includes a fuse 46 (including, as an embodiment, a precharge relay 68 and a precharge resistor 70) as a second heat-generating component located upstream of each fan motor 32 (positive and negative fan motors 32a, 32b) in the airflow directions α, β, and the heat generation amount of the fuse 46 (and the precharge relay 68 and the precharge resistor 70) is smaller than the heat generation amount of each relay 44. That is, air passing through the upstream side (suction path 90) of each fan motor 32a, 32b flows downstream of each fan motor 32a, 32b (airflow path 88), but the second heat-generating component with a relatively small heat generation amount is located upstream of each fan motor 32a, 32b. Therefore, the temperature rise of the air due to the second heat-generating component upstream of each fan motor 32a, 32b is suppressed to some extent, and relatively low-temperature air can be blown downstream of each fan motor 32a, 32b, where the first heat-generating component (relays 44) with a relatively large heat generation amount is located. This prevents relatively high-temperature air from being blown downstream of the fan motors 32a and 32b, and allows stable heat dissipation from the relays 44, which generate a relatively large amount of heat.

[0093] Furthermore, in the first embodiment, the cross-sectional area of ​​the airflow path 88 downstream of the negative pole fan motor 32b in the negative pole main body 29b is substantially constant in a direction perpendicular to the airflow direction β (direction perpendicular to the left-right direction). In particular, in the first embodiment, the cross-sectional areas of the suction path 90 upstream of the negative pole fan motor 32b and the airflow path 88 downstream of the negative pole main body 29b in the direction perpendicular to the airflow direction β are substantially constant. This allows air to flow with a substantially constant cross-sectional area throughout substantially the entire negative pole main body 29b. As a result, the occurrence of portions in the negative pole main body 29b where the air flow is difficult is suppressed, and localized temperature increases, for example, can be avoided.

[0094] Each of the intake holes 36a, 36b of each of the cases 34a, 34b includes a plurality of intake slits 106 penetrating the respective case 34a, 34b, and each of the exhaust holes 38a, 38b of each of the cases 34a, 34b includes a plurality of exhaust slits 108 penetrating the respective case 34a, 34b. The total cross-sectional area of ​​the plurality of intake slits 106 is preferably equal to or greater than the cross-sectional area perpendicular to the axis of each of the fan motors 32a, 32b, and the total cross-sectional area of ​​the plurality of exhaust slits 108 is preferably equal to or greater than the cross-sectional area perpendicular to the axis of each of the fan motors 32a, 32b. This allows air from the external space of each of the circuit unit bodies 29a, 29b to be stably drawn in through the intake slits 106 and flow to each of the fan motors 32a, 32b, and allows air that has passed through each of the fan motors 32a, 32b to be stably discharged to the external space through the exhaust slits 108.

[0095] Each heat sink 56 includes a plurality of heat dissipation plates 60 arranged in parallel, and at least one exhaust slit 108 is arranged opposite the gap 62 between each of the heat dissipation plates 60, 60. This allows air that has passed through the gap 62 between each of the heat dissipation plates 60, 60 to flow into the exhaust slit 108 without changing the airflow directions α and β, and the air that has passed through each of the heat sinks 56 can be stably exhausted through the exhaust slit 108 to the external space of each of the circuit unit bodies 29 a, 29 b.

[0096] A positive electrode circuit unit 10a and a negative electrode circuit unit 10b are disposed inside the battery pack 12, and the intake holes 36a, 36b of each circuit unit main body 29a, 29b are disposed in a central region 132 inside the battery pack 12, spaced apart from each other across an intake gap 130. Furthermore, the exhaust holes 38a, 38b of each circuit unit main body 29a, 29b are disposed in peripheral regions 134 inside the battery pack 12. According to this circuit unit arrangement structure 11, exhaust from each circuit unit main body 29a, 29b can be stably achieved compared to, for example, a case where the exhaust holes 38a, 38b of each circuit unit main body 29a, 29b are directed toward the center inside the battery pack 12. Furthermore, by arranging each exhaust hole 38a, 38b in each peripheral region 134 of the battery pack 12, the air discharged from each exhaust hole 38a, 38b can be brought into stable contact with the wall portion constituting the housing main body 24, and air at a lower temperature than the discharged air can be drawn in again from each intake hole 36a, 36b.

[0097] Second Embodiment A circuit unit main body constituting a circuit unit according to a second embodiment of the present disclosure will be described below with reference to FIGS. 15 to 22 . This circuit unit main body is a positive electrode main body 140, and the circuit unit main body (positive electrode main body 140) and an exhaust direction restricting portion constitute a circuit unit (positive electrode circuit unit) according to the second embodiment. A positive electrode restricting portion 40a similar to that of the first embodiment may be employed as the exhaust direction restricting portion. Furthermore, a negative electrode circuit unit 10b similar to that of the first embodiment may be employed inside the battery pack 12. That is, the second embodiment differs from the first embodiment in the structure of the positive electrode main body constituting the positive electrode circuit unit. Therefore, in the second embodiment, the structure of the positive electrode main body 140 will be mainly described, and a description of other parts of the battery pack 12 will be omitted. Furthermore, in the positive electrode main body 140, components and parts that are substantially the same as those in the first embodiment will be designated by the same reference numerals in the drawings, and detailed description thereof will be omitted.

[0098] The basic structure of the positive pole main body 140 is the same as that of the first embodiment, and includes a circuit configuration section (positive pole circuit configuration section 142) configured to include the heat-generating component 14, a fan motor (positive pole fan motor 144), and a case (positive pole case 146) that houses the positive pole circuit configuration section 142 and the positive pole fan motor 144. The positive pole case 146 is provided with an intake hole (positive pole intake hole 148) provided upstream of the positive pole fan motor 144 in the airflow direction γ (see FIG. 18 ), and an exhaust hole (positive pole exhaust hole 150) provided downstream of the airflow direction γ.

[0099] In the second embodiment as well, the heat-generating component 14 includes a first heat-generating component and a second heat-generating component, the first heat-generating component being a relay 44, and the second heat-generating component being a fuse 46. In particular, in the second embodiment, a pair of relays 44, 44 are stacked and spaced apart from each other in the vertical direction, and each of these relays 44 is provided in the left portion of the positive electrode main body 140. The fuse 46 is provided in the front region in the right portion of the positive electrode main body 140.

[0100] A heat sink 152 is thermally connected to each terminal 50 of each relay 44. In the second embodiment, each pair of relays 44, 44 is disposed with its front side facing forward. As shown in FIGS. 16 and 21 , one heat sink 152a is fixed to each left-side terminal 50 of each of the upper and lower relays 44 by bolts 64. Also, one heat sink 152b, 152c is fixed to each right-side terminal 50 of each of the upper and lower relays 44 by bolts 64. The plate-shaped portion 58 of each of the heat sinks 152a to 152c extends in a direction perpendicular to the front-rear direction, and a plurality of heat sinks 60 protrude from each plate-shaped portion 58 toward the front side, which is the side of the terminal 50 of each relay 44. These heat sinks 60 are spaced apart from each other in the vertical direction and extend in the horizontal direction. This provides gaps 62 extending in the horizontal direction between the heat sinks 60 in the vertical direction. As mentioned above, the protruding height from each terminal portion 50 of the insulating partition plate 52 in each relay 44 is A, while the protruding height from each terminal portion 50 of each heat sink 60 is D (see Figure 20), and the protruding height D from each terminal portion 50 of each heat sink 60 is greater than the protruding height A from each terminal portion 50 of each insulating partition plate 52.

[0101] As described above, the fuse 46 is provided in the front region of the right part of the positive pole main body 140, and the precharge relay 68 and precharge resistor 70 are provided in the rear region of the right part of the positive pole main body 140.

[0102] <Circuit Configuration Section (Positive Pole Circuit Configuration Section 142)> The relays 44 and fuses 46 are electrically connected by a plurality of current-carrying bus bars 154. Specifically, current-carrying bus bars 154a, 154b are fixed to the terminals 74 of the fuses 46 with bolts 76. As shown in FIG. 22 , current-carrying bus bar 154c is fixed to the right terminal 50 of the lower relay 44 together with a heat sink 152c with bolts 64, and current-carrying bus bar 154d is fixed to the right terminal 50 of the upper relay 44 together with a heat sink 152b with bolts 64. Furthermore, current-carrying bus bar 154e is fixed to the left terminals 50 of the upper and lower relays 44 together with a heat sink 152a with bolts 64. The current-carrying bus bars 154b and 154c are electrically connected to each other.

[0103] As a result, the end of the current-carrying bus bar 154a forms an external connection portion 78 at the right end of the positive electrode main body 140. Furthermore, the ends of the current-carrying bus bars 154d and 154e form external connection portions 80 at the left end of the positive electrode main body 140.

[0104] Therefore, in embodiment 2, the positive pole circuit configuration section 142 in the positive pole main body 140 is configured to include each relay 44, which is the first heat-generating component, the fuse 46, which is the second heat-generating component, the pre-charge relay 68, the pre-charge resistor 70, and each current-carrying bus bar 154a to 154e.

[0105] In the second embodiment, a plurality of heat dissipation bus bars 82 are also fastened together with bolts 76 at the fastening points between the terminal portions 74 of the fuse 46 and the current-carrying bus bars 154a, 154b and at the connecting points between the current-carrying bus bars 154b, 154c. As shown in FIG. 22 , the upper end of the current-carrying bus bar 154c and the lower end of the current-carrying bus bar 154d each have a heat dissipation portion 155 that protrudes forward. When the heat sinks 152b, 152c are fixed to the relays 44, the heat dissipation portions 155 are arranged at approximately equal intervals in the up-down direction relative to the heat dissipation plates 60 of the heat sinks 152b, 152c. Therefore, the heat dissipation effect is achieved not only by the heat sinks 152a to 152c but also by the heat dissipation portions 155.

[0106] <Divider Plate 156> The interior space of the positive electrode case 146 is divided into front and rear sections by a partition plate 156. The partition plate 156 is a plate-shaped member extending in the left-right direction as a whole and is formed of metal or synthetic resin. This partition plate 156 is attached from above the positive electrode circuit component 142 and is provided across the current-carrying bus bar 154a and the heat-dissipating bus bars 82. The partition plate 156 can be fixed to a positive electrode lower case 170 (described later) that constitutes the positive electrode case 146, for example, with bolts (not shown). By providing this partition plate 156 inside the positive electrode case 146, the pre-charge relay 68, pre-charge resistor 70, etc. are located in an area behind the partition plate 156, and the relays 44, fuses 46, etc. are located in an area ahead of the partition plate 156. Although the partition plate 156 extends in the left-right direction overall, it has a crank-shaped portion that bends in the front-to-back direction on the left side, and gaps 158 of a predetermined size are formed between the partition plate 156 and each relay 44 and each heat sink 152b, 152c.

[0107] <Positive pole fan motor 144> The positive pole fan motor 144 is disposed in the front region of the internal space of the positive pole case 146, which is partitioned in the front-rear direction by a partition plate 156. In the second embodiment, the positive pole fan motor 144 is disposed at the right end of the positive pole case 146, and an internal blade (not shown) rotates around the central axis N, generating an airflow from right to left in the positive pole main body 140. The airflow (airflow direction γ) generated by the positive pole fan motor 144 in the positive pole main body 140 is indicated by a two-dot chain line in FIG. 18. In the second embodiment, the positive pole case 146 is provided with a partition plate 156 that partitions the internal space into front and rear sides, and the positive pole fan motor 144 is disposed in the region forward of the partition plate 156, so that the air blown by the positive pole fan motor 144 is applied to the region forward of the partition plate 156.

[0108] That is, in the second embodiment, the relays 44, which are the first heat-generating components, and the fuse 46, which is the second heat-generating component, are both arranged downstream (to the left) of the positive-pole fan motor 144 in the airflow direction γ, and are not arranged upstream (to the right). In other words, an airflow path 160 extending downstream from the positive-pole fan motor 144 in the airflow direction γ of the positive-pole fan motor 144 is formed by the space in front of the partition plate 156, and the relays 44, which are the first heat-generating components, and the fuse 46, which is the second heat-generating component, are arranged within this airflow path 160. Furthermore, this airflow path 160 is configured to include, in addition to the positive-pole case 146, the partition plate 156 that is arranged within the positive-pole case 146 and separates the internal space of the positive-pole case 146. In particular, within the airflow path 160, the fuse 46, which generates a relatively small amount of heat, is arranged upstream, and the relays 44, which generate a relatively large amount of heat, are arranged downstream.

[0109] More specifically, the airflow path 160 is a space through which airflow generated by driving the positive pole fan motor 144 can pass through the positive pole main body 140 in the left-right direction. An opening 162 on the upstream side (right side) of the airflow path 160 is large enough to surround the positive pole fan motor 144 when viewed in the left-right direction, and an opening 164 on the downstream side (left side) of the airflow path 160 is large enough to surround the relays 44 and the heat sinks 152a to 152c when viewed in the left-right direction. In particular, in the second embodiment, in the region of the airflow path 160 from the positive pole fan motor 144 to the heat sinks 152b, 152c, the cross-sectional area of ​​the airflow path 160 in a direction perpendicular to the airflow direction γ (direction perpendicular to the left-right direction) is approximately constant, and the cross-sectional area of ​​the airflow path 160 is increased at the crank-shaped bend in the partition plate 156.

[0110] Here, the air flowing downstream (leftward) from the positive pole fan motor 144 comes into contact with the heat sinks 152b, 152c and the relays 44, causing a portion of the air to change direction, and a portion of the air flows into the gap 158 between the partition plate 156 and the heat sinks 152b, 152c and the relays 44. The air flowing into this gap 158 flows along the surface of the case body 48 of each relay 44, inside which the coil 54 is housed, between the relay 44 and the partition plate 156. Therefore, in the second embodiment, the air flow path 160 is configured to include a body cooling path 166 that blows air onto the surface of the case body 48 of each relay 44.

[0111] The crank-shaped bent portion of the partition plate 156 (i.e., the main body cooling path 166) is not essential, and the air flow path 160 may extend substantially straight in the left-right direction. In this case, for example, the case main body 48 of each relay 44 is located rearward of the partition plate 156, and the opening 164 on the downstream side (left) of the air flow path 160 is formed with a size that surrounds each of the heat sinks 152a to 152c when viewed in the left-right direction. Even with this configuration, the air blown from the positive pole fan motor 144 acts on each of the heat sinks 152a to 152c, thereby achieving a good heat dissipation effect.

[0112] <Positive electrode case 146> The positive electrode case 146 of the second embodiment has the same shape as the positive electrode case 34a of the first embodiment and includes a positive electrode upper case 168 and a positive electrode lower case 170. A positive electrode intake hole 148 is formed in the right portion of the positive electrode upper case 168, and a positive electrode exhaust hole 150 is formed in the left portion of the positive electrode lower case 170. The positive electrode intake hole 148 includes a plurality of intake slits 106, which are aligned in the front-rear direction and / or the left-right direction. The positive electrode exhaust hole 150 includes a plurality of exhaust slits 108, which are aligned in the front-rear direction and / or the left-right direction.

[0113] The positive electrode main body 140 of embodiment 2, which has the above-described structure, is also combined with the positive electrode regulating portion 40a provided on the housing main body 24 of the battery pack 12 to form a positive electrode circuit unit, thereby achieving the same effects as in embodiment 1.

[0114] In particular, in the second embodiment, the relays 44 and fuses 46, which are heat-generating components 14, are arranged downstream of the positive pole fan motor 144 in the airflow direction γ, and are not arranged upstream of the positive pole fan motor 144 in the airflow direction γ. This prevents the positive pole fan motor 144 from being affected by air whose temperature rises due to heat generated by the heat-generating components 14. Furthermore, the air whose temperature rises as it passes through the heat-generating components 14 is cooled by coming into contact with the housing main body 24 while being discharged from the positive pole exhaust hole 150 and circulating to the positive pole intake hole 148. This reliably prevents high-temperature air from affecting the positive pole fan motor 144 and adversely affecting its operation. Furthermore, because the fuse 46, which generates a relatively small amount of heat, is arranged upstream within the airflow path 160, high-temperature air is not exposed to the downstream side, and heat dissipation from the relays 44, which generate a relatively large amount of heat, can be reliably achieved.

[0115] In each of the heat sinks 152a to 152c thermally connected to the terminal portion 50 of each relay 44, the protruding height D of each heat sink 60 from the terminal portion 50 is made larger than the protruding height A of each insulating partition plate 52 from the terminal portion 50 of each relay 44. This allows the air blown from the positive pole fan motor 144 to reach each heat sink 60 without being obstructed by each insulating partition plate 52, thereby preventing a decrease in heat dissipation efficiency.

[0116] The airflow path 160 is configured to include a partition plate 156 that is disposed within the positive electrode case 146 and separates the internal space of the positive electrode case 146. As a result, the relays 44 and fuses 46 that generate a relatively large amount of heat are disposed within the airflow path 160, while the pre-charge relays 68 and pre-charge resistors 70 that generate a relatively small amount of heat are disposed outside the airflow path 160. As a result, the air blown by the positive electrode fan motor 144 can be efficiently applied to the relays 44 and fuses 46, and heat dissipation from the relays 44 and fuses 46 that generate a relatively large amount of heat can be stably achieved.

[0117] An opening 162 on the upstream side of the airflow path 160 is large enough to surround the positive pole fan motor 144, and an opening 164 on the downstream side of the airflow path 160 is large enough to surround the heat sinks 152a to 152c and the relays 44. This prevents the air from passing through a narrow path when it is drawn in through the positive pole intake hole 148 and exhausted through the positive pole exhaust hole 150, preventing restriction of air circulation.

[0118] The air flow path 160 includes a body cooling path 166 that blows air to the surface of the case body 48 of each relay 44. This allows efficient heat dissipation not only from the terminal portion 50 of each relay 44 but also from the coil 54 of each relay 44, thereby improving the heat dissipation efficiency of each relay 44.

[0119] Third Embodiment A positive electrode main body 180, which is a circuit unit main body constituting a circuit unit according to a third embodiment of the present disclosure, will now be described with reference to Figures 23 and 24. Note that Figure 23 shows the positive electrode main body 180 with the positive electrode upper case 168 constituting the positive electrode case 146 removed. The basic structure of the positive electrode main body 180 in the third embodiment is similar to that of the positive electrode main body 140 in the second embodiment. However, in the third embodiment, as also shown in Figure 24, heat dissipation portions 155, 155 that protrude forward are also provided at both vertical ends of the portion of the energizing bus bar 154e that is fixed to the terminal portion 50 of each relay 44 (the right portion of the energizing bus bar 154e).

[0120] Furthermore, in the second embodiment, one heat sink 152a is fixed to each left terminal portion 50 of each relay 44 via the current-carrying bus bar 154e by the bolts 64, but in the third embodiment, one heat sink 182a, 182b is fixed to each left terminal portion 50 of each relay 44 via the current-carrying bus bar 154e by the bolts 64. As a result, in the third embodiment, a total of four heat sinks 182a to 182d, including the heat sinks 182c, 182d that are superimposed on and fixed to the current-carrying bus bars 154d, 154c, are thermally connected to each terminal portion 50 of each relay 44.

[0121] The positive pole body 180 in embodiment 3 differs from the positive pole body 140 in embodiment 2 only in the shape of the current-carrying bus bar 154e and the number of heat sinks 182a to 182d. Also in embodiment 3, heat generated at each terminal portion 50 of each relay 44 is dissipated by each heat sink 182a to 182d as well as by each heat dissipation portion 155 of each current-carrying bus bar 154c to 154e, so the positive pole body 180 in embodiment 3 can achieve the same effect as in embodiment 2.

[0122] <First Modification of Third Embodiment> A positive electrode main body 190 will be described below as a first modification of the third embodiment of the present disclosure with reference to Figures 25 and 26. In this first modification, a heat sink is integrally provided on the head 194 of a bolt 192 for fastening the current-carrying bus bars 154c to 154e and the heat sinks 184a to 184d to the terminal portion 50 of each relay 44. In other words, the head 194 of the bolt 192 is provided with a plurality of protrusions 196 that protrude forward and have an increased surface area and function as heat sinks. The protrusions 196 extend in the same direction (left-right direction) as the heat sinks 60 of the heat sinks 184a to 184d, and are spaced apart from each other in the up-down direction.

[0123] In this way, the projections 196 provided on the heads 194 of the bolts 192 extend in the left-right direction, thereby preventing obstruction to the airflow from the positive pole fan motor 144. Furthermore, heat generated at the terminal portions 50 of the relays 44 can be dissipated not only by the heat dissipation portions 155 of the heat sinks 184a to 184d and the current-carrying bus bars 154c to 154e but also by the bolts 192 that secure them, thereby improving heat dissipation efficiency.

[0124] <Modification 2 of Embodiment 3> A positive electrode main body 200 will be described below as Modification 2 of Embodiment 3 of the present disclosure with reference to Figures 27 and 28. In Modification 2, each of the current-carrying bus bars 202a, 202b, and 202c, which are overlapped with the terminal portions 50 of the relays 44 and secured by the bolts 64, includes a wavy portion 204 in a portion thereof. Specifically, for example, the current-carrying bus bar 202a is secured by bolts at both ends in the longitudinal direction (left-right direction). These ends are provided with flat portions 206 that extend flatly so that the fastening force of the bolts can be stably applied, and the wavy portion 204 is provided in a middle portion in the left-right direction outside the flat portions 206. Furthermore, the current-carrying bus bar 202b has the wavy portion 204 at its right end, and the current-carrying bus bar 202c has the wavy portion 204 in a middle portion in the left-right direction.

[0125] More specifically, the corrugated portion 204 has a shape in which peaks 208 that convex in one direction in the thickness direction and valleys 210 that convex in the other direction in the thickness direction are alternately repeated and continuous, and these peaks 208 and valleys 210 are connected by a smoothly curved surface. These peaks 208 and valleys 210 each extend in the left-right direction, which is the same direction as the airflow direction γ of the positive pole fan motor 144.

[0126] Each of the current-carrying bus bars 202a to 202c is fixed to the terminal portion 50 of each of the relays 44 by a bolt 64, and is in thermal contact with the terminal portion 50 of each of the relays 44. The surface area of ​​each of the current-carrying bus bars 202a to 202c is increased at each of the wavy portions 204, so that when the terminal portion 50 of each of the relays 44 generates heat, the air blown from the positive pole fan motor 144 acts on the wavy portions 204 of each of the current-carrying bus bars 202a to 202c, thereby efficiently dissipating the heat generated at the terminal portion 50 of each of the relays 44. In particular, because the peaks 208 and valleys 210 of each of the wavy portions 204 extend in the left-right direction, the air blown from the positive pole fan motor 144 is not obstructed, and stable heat dissipation can be achieved. In the second modification, the heat sinks 152a to 152c and 182a to 182d described in the second and third embodiments, and the bolts 192 having heat sinks may be used in combination.

[0127] 29 to 32, a circuit unit main body constituting a circuit unit according to a fourth embodiment of the present disclosure will be described. This circuit unit main body is a positive electrode main body 220, and its basic structure is similar to that of the positive electrode main body 29a of the first embodiment, but the positive electrode main body 220 of the fourth embodiment has a path branch portion 224 in the air flow path 222. In the following description, members and parts that are substantially the same as those of the first embodiment are denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted.

[0128] The positive pole main body 220 includes a circuit configuration section (positive pole circuit configuration section 226) configured to include the heat-generating component 14, a fan motor (positive pole fan motor 228), and a case (positive pole case 230) that houses the positive pole circuit configuration section 226 and the positive pole fan motor 228. The positive pole case 230 is provided with an intake hole (positive pole intake hole 232) provided upstream of the positive pole fan motor 228 in the airflow direction δ (see FIG. 30 ), and an exhaust hole (positive pole exhaust hole 234) provided downstream of the airflow direction δ.

[0129] In the fourth embodiment, a pair of relays 44, 44 are disposed laterally spaced apart on the left side of the positive electrode main body 220, and a fuse 46, a pre-charge relay 68, and a pre-charge resistor 70 are disposed on the right side of the positive electrode main body 220. These heat-generating components 14 are electrically connected by a plurality of energizing bus bars 236a-236f. ​​Therefore, in the fourth embodiment, the positive electrode circuit configuration unit 226 includes the relays 44, fuses 46, pre-charge relays 68, pre-charge resistors 70, and energizing bus bars 236a-236f. ​​Heat-dissipating bus bars 238a-238h are thermally connected to these energizing bus bars 236a-236f.

[0130] A positive pole fan motor 228 is disposed in the left-right center of the positive pole main body 220. The positive pole fan motor 228 generates an airflow from right to left by rotating a blade (not shown) provided inside the positive pole fan motor 228 around a central axis O. The airflow (airflow direction δ) generated by the positive pole fan motor 228 in the positive pole main body 220 is indicated by a two-dot chain line in Figure 30. That is, within the internal space of the positive pole main body 220, the space downstream (left) of the positive pole fan motor 228 is the airflow path 222, and the space upstream (right) of the positive pole fan motor 228 is the suction path 240.

[0131] The positive electrode case 230 includes a positive electrode upper case 242 and a positive electrode lower case 244. The positive electrode lower case 244 is provided with a path branching portion 224 that branches the air flowing through the air flow path 222. Specifically, the positive electrode lower case 244 is provided downstream (left) of the positive electrode fan motor 228 with a pair of outer guide walls 246, 246 whose opposing dimensions (front-to-rear dimension) gradually increase toward the left, and a pair of inner guide walls 248, 248 extending generally parallel to the outer guide walls 246 in the front-to-rear direction between the outer guide walls 246. The inner guide walls 248, 248 are connected to each other at their right ends, and the path branching portion 224 is formed at this connection. In other words, when the airflow generated by driving the positive pole fan motor 228 collides with the path branching section 224, the airflow branches to both the front and rear sides and flows downstream at both the front and rear ends of the positive pole case 230.

[0132] In the fourth embodiment, a wavy portion 250 is provided on at least one of the current-carrying bus bars 236c to 236f arranged in the airflow path 222 (i.e., downstream of the positive pole fan motor 228), and a wavy portion 250 is provided on at least one of the heat-dissipating bus bars 238e to 238h arranged in the airflow path 222. In particular, in the fourth embodiment, a wavy portion 250 is provided on the current-carrying bus bar 236f, and a wavy portion 250 is provided on the heat-dissipating bus bar 238g.

[0133] The wavy portion 250 of the current-carrying bus bar 236f and the wavy portion 250 of the heat-dissipating bus bar 238g are each located on airflow paths 222 that branch out on both sides in the front-rear direction. In the fourth embodiment, the wavy portion 250 of the current-carrying bus bar 236f is located in the front portion of the positive electrode case 230, and the wavy portion 250 of the heat-dissipating bus bar 238g is located in the rear portion of the positive electrode case 230. Each wavy portion 250 is configured by peaks 252 that convex on one side in the plate thickness direction and valleys 254 that convex on the other side in the plate thickness direction, which are alternately and continuously arranged in the up-down direction, and extends in the left-right direction with a predetermined length.

[0134] In this way, the positive electrode main body 220 having the branched airflow paths 222 can also achieve the same effects as in embodiment 1. In particular, in embodiment 4, the current-carrying bus bar 236f and the heat-dissipating bus bar 238g each have a wavy portion 250, and the increased surface area of ​​these wavy portions 250 can improve the heat dissipation effect when air is blown by the positive electrode fan motor 228. Furthermore, in each wavy portion 250, the peaks 252 and valleys 254 extend in the left-right direction, which is the same direction as the airflow direction δ, thereby preventing the airflow from being obstructed.

[0135] <Modifications> Although the first to fourth embodiments and the first and second modifications of the third embodiment have been described above as specific examples of the present disclosure, the present disclosure is not limited by these specific descriptions. Modifications, improvements, etc., within the scope of achieving the object of the present disclosure, are included in the present disclosure. For example, the following modifications of the embodiments are also included in the technical scope of the present disclosure.

[0136] (1) In a circuit unit main body constituting a circuit unit according to the present disclosure, a hinged opening / closing section may be provided in a portion of the case to facilitate replacement of a fan motor provided in the circuit unit. For example, as shown in FIG. 33 , a hinged opening / closing section 262 that can be opened and closed by rotating around an axis may be provided on the right end and front side of the positive pole upper case 168 in the positive pole main body 140 described in the second embodiment. The upper view in FIG. 33 shows the hinged opening / closing section 262 in an open state, and the lower view in FIG. 33 shows the hinged opening / closing section 262 in a closed state. By opening the hinged opening / closing section 262 as shown in the upper view in FIG. 33 , replacement of the positive pole fan motor 144 can be facilitated, and by closing the hinged opening / closing section 262 as shown in the lower view in FIG. 33 , the intrusion of dust and the like into the positive pole main body 260 can be prevented. This configuration may be applied to the first or fourth embodiment, and the hinge opening / closing portion may be provided in the center of the case in the left-right direction, so that the fan motor provided in the center of the case in the left-right direction can be easily replaced.

[0137] (2) For example, in the first embodiment, the exhaust direction restricting portions 40 (positive and negative pole restricting portions 40a, 40b) are provided separately from the circuit unit main body 29 (positive and negative pole main bodies 29a, 29b) on the left and right wall portions of the housing main body 24 of the battery pack 12. However, this is not limited to this. For example, the exhaust direction restricting portions 40 may be provided on the circuit unit main body 29, as in the circuit unit 270 (positive pole circuit unit 270a and negative pole circuit unit 270b) shown in FIG. 34 , and may be formed integrally with the case 34, or may be formed separately and then fixed thereto. The same applies to the second to fourth embodiments and the first and second modifications of the third embodiment.

[0138] Alternatively, as in the circuit unit (positive-electrode circuit unit 280) shown in FIG. 35 , the shape of the case (positive-electrode case 146) may be configured to control the direction of air blown from the fan motor 144 (restrict the direction of exhaust). In particular, in this embodiment, a partition plate 282 provided inside the positive-electrode case 146 has an inclined portion 284 that inclines forward at the left end of the positive-electrode case 146. As a result, the air that comes into contact with the heat sinks 152 b, 152 c and the relays 44 and branches into the rear main body cooling path 166 as in the second embodiment is guided by the inclined portion 284 and flows forward as it moves leftward. That is, in this embodiment, the fan motor 144 blows air in two directions γ1 and γ2: a blowing direction γ1 (shown by a two-dot chain line in FIG. 35 ) that travels substantially straight from right to left, and a blowing direction γ2 (shown by a two-dot chain line in FIG. 35 ) that branches off rearward midway along the blowing direction γ1 and is guided forward at the left end along the inclined portion 284. The air blown in these directions γ1 and γ2 joins together at the left end of the positive electrode case 146 and is exhausted forward (in a direction away from the battery cells 18 in the battery pack 12) through the positive electrode exhaust hole 150. As a result, air heated by the heat-generating components 14 (relays 44 and fuses 46) is prevented from flowing toward the battery modules 16 (battery cells 18) and adversely affecting the battery modules 16. Therefore, in this embodiment, the inclined portion 284 constitutes an exhaust direction restricting portion that directs exhaust air from the exhaust hole (positive electrode exhaust hole 150) in a direction away from the battery module 16. In particular, in this embodiment, the positive electrode exhaust hole 150 is provided only in the front portion of the positive electrode upper case 168, so that exhaust air in a direction away from the battery module 16 is stably discharged.

[0139] If the case does not include a partition, the left end of the case may include a wall that slopes forward as it extends from the rear wall to the left, and the wall may be used to define the exhaust direction restriction. Alternatively, the exhaust holes (exhaust slits) may be configured to slope forward as they extend to the left, thereby defining the exhaust direction restriction. When the above-described structure is adopted, the exhaust direction restriction is defined by the shape of the case (including the partition) and the exhaust holes, thereby avoiding the need for a separate exhaust direction restriction. Even when the exhaust direction restriction is provided on the battery pack, it is not limited to being provided on the left and right walls of the housing body, but may also be provided on the bottom wall or the lid.

[0140] (3) In the above embodiment, the intake holes (positive electrode intake holes 36a, 148, 232 and negative electrode intake holes 36b) and the exhaust holes (positive electrode exhaust holes 38a, 150, 234 and negative electrode exhaust holes 38b) are configured by a plurality of intake slits 106 and exhaust slits 108, respectively. However, this is not limited to this. The intake holes and exhaust holes according to the present disclosure may be a single hole that penetrates the case in the thickness direction. Furthermore, these intake holes and exhaust holes are not limited to being provided in the upper case that constitutes the case. They may also be provided in the lower case, or in both the upper and lower cases.

[0141] (4) For example, in the first embodiment, the bolt 192 having a heat sink described in the first modified example of the third embodiment may be employed, or the current-carrying bus bars 72d to 72g connected to the relays 44 in the first embodiment may be formed with the wavy portions described in the second modified example of the third embodiment or the fourth embodiment. That is, at least two of the first to fourth embodiments and the first and second modified examples of the third embodiment may be employed in combination, if possible.

[0142] (5) In the fourth embodiment, the path branching section 224 that branches the air flowing through the air supply path 222 is provided in the positive electrode lower case 244. However, the path branching section may be provided in the upper case that constitutes the case, or may be provided in both the upper case and the lower case.

[0143] REFERENCE SIGNS LIST 10 Circuit unit (first embodiment) 10a Positive electrode circuit unit 10b Negative electrode circuit unit 11 Circuit unit arrangement structure 12 Battery pack 14 Heat-generating component 16 Battery module 18 Battery cell 20 Housing 22 BMS board 24 Housing body 26 Upper opening 28 Lid 29 Circuit unit body 29a Positive electrode body 29b Negative electrode body 30 Circuit configuration section 30a Positive electrode circuit configuration section 30b Negative electrode circuit configuration section 32 Fan motor 32a Positive electrode fan motor 32b Negative electrode fan motor 34 Case 34a Positive electrode case 34b Negative electrode case 36 Intake hole 36a Positive electrode intake hole 36b Negative electrode intake hole 38 Exhaust hole 38a Positive electrode exhaust hole 38b Negative electrode exhaust hole 40 Exhaust direction restricting portion 40a Positive electrode restricting portion 40b Negative electrode restricting portion 42 Inclined surface 44 Relay (first heat-generating component) 46 Fuse (second heat-generating component) 48 Case body 50 Terminal portion 52 Insulating partition plate 54 Coil 56 Heat sink 58 Plate-shaped portion 60 Heat sink 62 Gap 64 Bolt 66 Insulating heat-conducting sheet 68 Pre-charge relay (second heat-generating component) 70 Pre-charge resistor (second heat-generating component) 72 Current-carrying bus bar 72a Portion of current-carrying bus bar covering the top of the relay 72b to 72g Current-carrying bus bar 74 Terminal portion 76 Bolt 78,80 External connection portion 82 Heat dissipation bus bar 84 Heat dissipation portion 86 Insulating heat conductive sheet 88 Air blowing path 90 Suction path 92 Exhaust duct 94 Side wall portion 96 Support frame 98 Positive electrode upper case 100 Positive electrode lower case 102 Upper bottom wall portion 104 Upper peripheral wall portion 104a Upper front wall portion 104b Upper rear wall portion 104c Upper left wall portion 104d Upper right wall portion 106 Intake slit 108 Exhaust slit 110 Lock recess 112 Electric wire insertion hole 112a Upper insertion hole 112b Lower insertion hole 114 Electric wire insertion hole 114a Upper insertion hole 114b Lower insertion hole 116 Bottom wall portion 118 Lower peripheral wall portion 120 Nut 122 Locking protrusion 124 Monitoring and driving portion 126 Negative pole upper case 128 Negative pole lower case 130 Intake gap 132 Central region 134 Peripheral region 140 Positive pole main body (circuit unit main body, embodiment 2) 142 Positive pole circuit configuration portion (circuit configuration portion) 144 Positive pole fan motor (fan motor) 146 Positive pole case (case) 148 Positive pole intake hole (intake hole) 150 Positive pole exhaust hole (exhaust hole) 152, 152a to 152c Heat sink 154,154a to 154e Current-carrying bus bars 155 Heat dissipation portion 156 Partition plate 158 Gap 160 Air flow path 162 Opening (upstream side of air flow path) 164 Opening (downstream side of air flow path) 166 Main body cooling path 168 Positive electrode upper case 170 Positive electrode lower case 180 Positive electrode main body (circuit unit main body, embodiment 3) 182a to 182d Heat sink 190 Positive electrode main body (circuit unit main body, modified example 1 of embodiment 3) 192 Bolt 194 Head 196 Protrusion 200 Positive electrode main body (circuit unit main body, modified example 2 of embodiment 3) 202a to 202c Current-carrying bus bars 204 Wave-shaped portion 206 Flat portion 208 Peak portion 210 Valley portion 220 Positive electrode main body (circuit unit main body, embodiment 4) 222 Air flow path 224 Path branching section 226 Positive electrode circuit configuration section (circuit configuration section) 228 Positive electrode fan motor (fan motor) 230 Positive electrode case (case) 232 Positive electrode intake hole (intake hole) 234 Positive electrode exhaust hole (exhaust hole) 236a to 236f Current-carrying bus bars 238a to 238h Heat-dissipating bus bars 240 Suction path 242 Positive electrode upper case 244 Positive electrode lower case 246 Outer guide wall section 248 Inner guide wall section 250 Wave-shaped section 252 Peak section 254 Valley section 260 Positive electrode main body (Figure 33) 262 Hinge opening / closing section 270 Circuit unit (Figure 34) 270a Positive electrode circuit unit 270b Negative electrode circuit unit 280 Circuit unit (Fig. 35) 282 Partition plate 284 Inclined portion (exhaust direction control portion) L, M, N, O Central axis α, β, γ, δ, γ1, γ2 Airflow direction,

Claims

1. A circuit unit mounted inside a battery pack in which a battery module is housed within a housing, comprising: a circuit configuration section including heat-generating components; a fan motor; a case that houses the circuit configuration section and the fan motor; an intake hole provided in the case on the upstream side of the air blowing direction of the fan motor; an exhaust hole provided in the case on the downstream side of the air blowing direction of the fan motor; and an exhaust direction regulating section that directs exhaust air from the exhaust hole in a direction away from the battery module.

2. The circuit unit according to claim 1, wherein the heat generating component includes a first heat generating component having a heat sink thermally connected to a terminal portion, and the first heat generating component and the heat sink are arranged downstream of the fan motor in the air blowing direction.

3. The circuit unit described in claim 2, wherein the heat-generating component includes a second heat-generating component arranged upstream of the fan motor in the air blowing direction, and the amount of heat generated by the second heat-generating component is smaller than the amount of heat generated by the first heat-generating component.

4. A circuit unit as claimed in any one of claims 1 to 3, wherein the heat-generating component is arranged downstream of the fan motor in the air blowing direction, and is not arranged upstream of the fan motor.

5. A circuit unit as described in claim 2 or claim 3, wherein the first heat-generating component is a relay, the heat sink includes a plurality of heat sink plates protruding from the terminal portion side, and the protruding height of the heat sink plates from the terminal portion is greater than the protruding height of an insulating partition plate protruding from the periphery of the terminal portion of the relay.

6. A circuit unit as described in any one of claims 1 to 3, including an air flow path extending from the fan motor toward the downstream side in the air flow direction of the fan motor, the heat-generating component being arranged within the air flow path, and the air flow path including a partition plate arranged within the case to divide the internal space of the case.

7. A circuit unit as described in claim 6 when claim 2 or claim 3 is cited, wherein the upstream opening of the air flow path is large enough to surround the fan motor, and the downstream opening of the air flow path is large enough to surround the heat sink or the first heat-generating component including the heat sink.

8. A circuit unit as described in claim 2 or claim 3, including an air flow path extending from the fan motor toward the downstream side in the air flow direction of the fan motor, the heat-generating component being arranged within the air flow path, and the cross-sectional area of ​​the air flow path in a direction perpendicular to the air flow direction is constant in a region of the air flow path from the fan motor to the heat sink.

9. A circuit unit as described in any one of claims 1 to 3, including an air flow path extending from the fan motor toward the downstream side in the air flow direction of the fan motor, the heat-generating component including a relay having a coil housed within a case body, and the air flow path including a body cooling path that blows air to a surface of the case body of the relay.

10. A circuit unit as described in any one of claims 1 to 3, wherein the air intake hole of the case includes a plurality of air intake slits penetrating the case, the exhaust hole of the case includes a plurality of exhaust slits penetrating the case, the total cross-sectional area of ​​the plurality of air intake slits is equal to or greater than the axial cross-sectional area of ​​the fan motor, and the total cross-sectional area of ​​the plurality of exhaust slits is equal to or greater than the axial cross-sectional area of ​​the fan motor.

11. A circuit unit as described in claim 10 when claim 2 or 3 is recited, wherein the heat sink includes a plurality of heat sink plates arranged in parallel, and at least one of the exhaust slits is arranged facing a gap between the heat sink plates.

12. The circuit unit according to claim 2 or 3, wherein the heat sink is provided integrally with a head of a bolt that is fastened to the terminal portion of the first heat generating component.

13. A circuit unit arrangement structure in which a pair of circuit units as described in any one of claims 1 to 3 are arranged inside the battery pack as a positive pole circuit unit and a negative pole circuit unit, the air intake hole of the positive pole circuit unit and the air intake hole of the negative pole circuit unit are arranged in a central region of the interior of the battery pack, separated from each other by an air intake gap, and the exhaust hole of the positive pole circuit unit and the exhaust hole of the negative pole circuit unit are arranged in the peripheral region of the interior of the battery pack.

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