Circuit unit

Abstract

To provide a circuit unit in which thermal effects on a current sensor and effects on a magnetic field by a current-carrying path are suppressed.SOLUTION: A circuit unit 10 includes a current sensor 12, a current-carrying path 16 including a sensing conductor part 14 whose current value is detected by the current sensor 12, and noncurrent-carrying heat transfer members 20a, 20b including heat transfer parts 18a, 18b thermally connected to the current-carrying path 16 and capable of contacting a heat-dissipating target 26 in a thermally conductive manner.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses a circuit unit that is mounted on a vehicle and disposed in a power supply path from a power source to a load. The circuit unit includes a current sensor that measures a current flowing through an electric current path housed inside. As the current in vehicles has become larger in recent years, the amount of heat generated by the current passing through the electric current path has also increased, raising concerns about the thermal effect on the current sensor. For this reason, in Patent Document 1, extensions that are bent in the same direction (downward) perpendicular to the detection conductor are provided on both sides of the detection conductor of the electric current path in which the current value is detected by the current sensor, and a heat transfer portion provided on the tip side of the extensions is thermally contacted with a heat dissipation target, thereby ensuring a heat dissipation path for the electric current busbar. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-015959 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when an electric current path is routed in this manner, it is likely that noise will be generated due to the strengthening of magnetic fields caused by the extending portions on both sides of the current sensor, which may lead to malfunction of the current sensor.

[0005] Therefore, a circuit unit is disclosed in which the thermal effect and the effect on the magnetic field of the current sensor due to the current path are suppressed. [Means for solving the problem]

[0006] The circuit unit of the present disclosure comprises a current sensor, an electric path including a detection conductor portion whose current value is detected by the current sensor, and a non-electrically conductive heat transfer member that is thermally connected to the electric path and includes a heat transfer portion that is in thermally conductive contact with a heat dissipation target. Effect of the Invention

[0007] According to the circuit unit of the present disclosure, it is possible to suppress the thermal effects and the effects of the magnetic field on the current sensor due to the current path. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional perspective view of a circuit unit according to a first embodiment, with a part of the case removed. [Diagram 2] FIG. 2 is an enlarged partial longitudinal sectional view of the II-II section in FIG. [Diagram 3] FIG. 3 is a vertical cross-sectional perspective view of the circuit unit according to the second embodiment, with a part of the case removed. [Figure 4] FIG. 4 is an enlarged partial longitudinal sectional view of the IV-IV section in FIG. [Diagram 5] FIG. 5 is a perspective view showing a model of a modified example of the circuit unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Description of the embodiments of the present disclosure> First, embodiments of the present disclosure will be listed and described. The circuit unit of the present disclosure includes: (1) A heat transfer device comprising: a current sensor; an electric path including a detection conductor portion whose current value is detected by the current sensor; and a non-electrically conductive heat transfer member that is thermally connected to the electric path and includes a heat transfer portion that is in thermally conductive contact with a heat dissipation target.

[0010] According to the circuit unit of this aspect, the non-electrically conducting heat transfer member includes a heat transfer part that is thermally connected to the electric current path including the detection conductor part sensed by the electric current sensor and is in contact with the heat dissipation target in a thermally conductive manner. This allows the non-electrically conducting heat transfer member to be arranged in a region separate from the wiring path of the electric current path, and the heat transfer part of the non-electrically conducting heat transfer member to be in thermally conductive contact with the heat dissipation target to ensure a heat dissipation path for the electric current path. Moreover, since the non-electrically conducting heat transfer member is non-conductive, no magnetic field is generated due to current flow, and the influence of the non-electrically conducting heat transfer member on the magnetic field of the current sensor is advantageously avoided or suppressed. This allows the heat dissipation of the electric current path to be promoted and the thermal influence on the current sensor to be suppressed even when a large current flows through the electric current path, and furthermore, even if a heat dissipation path using the non-electrically conducting heat transfer member is used, the influence on the magnetic field of the current sensor can be suppressed.

[0011] As the current sensor, either a type with a core or a type without a core can be used as long as it is a magnetic field detection type.

[0012] (2) In the above (1), it is preferable that the electric current path has a pair of parallel parts extending from both sides of the extension direction of the detection conductor in a direction away from the current sensor in parallel with the detection conductor, and the non-electrically conductive heat transfer member is thermally connected to the electric current path at the base end side of at least one of the parallel parts. Since the electric current path has a pair of parallel parts extending from both sides of the extension direction of the detection conductor in parallel with the detection conductor, it is advantageously possible to avoid forming an electric current region extending in the same direction intersecting the detection conductor in the vicinity of the detection conductor. As a result, it is possible to advantageously suppress the generation of noise accompanied by magnetic field coupling due to the electric current path in the vicinity of the current sensor, and the magnetic resistance of the current sensor can be improved. In addition, since the non-electrically conductive heat transfer member is thermally connected to the electric current path at the base end side of the parallel parts, it is possible to ensure a heat dissipation path of the electric current path in the vicinity of the current sensor, and the heat resistance of the current sensor can also be improved.

[0013] (3) In the above (2), it is preferable that the heat transfer portion of the non-electrically conducting heat transfer member is in contact with the heat dissipation target on the current sensor side of the protruding end of the parallel portion. The heat transfer portion of the non-electrically conducting heat transfer member is in contact with the heat dissipation target closer to the current sensor than the protruding end of the parallel portion. This allows heat from the current path to be dissipated quickly near the current sensor, and further improves the heat resistance and magnetic resistance of the current sensor.

[0014] (4) In the above (2) or (3), it is preferable that the current sensor has a housing that houses the detection conductor and a pair of terminals that are connected to both sides of the detection conductor and protrude from both sides of the housing, each of the parallel parts of the electric current path and the non-electrically conductive heat transfer member is formed by a bus bar made of a metal plate, the base end of the parallel parts is fastened to the pair of terminal parts of the current sensor, and the non-electrically conductive heat transfer member is fastened to the terminal part together with the base end of at least one of the parallel parts. Since the current sensor has a pair of terminal parts on both sides of the housing that houses the detection conductor, it is possible to easily and efficiently configure an electric current path that has parallel parts protruding from both sides of the detection conductor by simply fastening each parallel part of the electric current path formed by a bus bar to the pair of terminal parts. Furthermore, it is possible to easily and efficiently configure a heat dissipation path of the electric current path near the current sensor by simply fastening the non-electrically conductive heat transfer member formed by a bus bar together with the parallel part to at least one of the terminal parts.

[0015] (5) In the above (1), it is preferable that the current path has a first intersection protruding from one end of the detection conductor to one side in the plate thickness direction of the detection conductor and a second intersection protruding from the other end of the detection conductor to the other side in the plate thickness direction of the detection conductor, and the non-electrically conductive heat transfer member is thermally connected to the current path at the base end side of at least one of the first intersection and the second intersection. Since the current path has the first intersection and the second intersection protruding on both sides of the detection conductor to one side and the other side in the plate thickness direction of the detection conductor, magnetic fields generated by the first intersection and the second intersection in the vicinity of the detection conductor cancel each other out. This makes it possible to advantageously suppress the generation of noise accompanied by magnetic field coupling due to the current path in the vicinity of the current sensor, and improve the magnetic resistance of the current sensor. In addition, since the non-electrically conducting heat transfer member is thermally connected to the electric path at the base end side of at least one of the first intersection and the second intersection, a heat dissipation path for the electric path can be secured in the vicinity of the current sensor, thereby improving the heat resistance of the current sensor.

[0016] (6) In the above (5), it is preferable that at least one of the first intersection and the second intersection is provided with a current-side heat transfer part that is in contact with the heat dissipation target so as to be capable of thermal conduction. The current-side heat transfer part can be advantageously provided at the first intersection or the second intersection that faces the case side, which may be the heat dissipation target, from the current sensor, while utilizing the cancellation of magnetic fields caused by the first intersection and the second intersection protruding to one side and the other side in the plate thickness direction of the detection conductor. This makes it possible to secure a heat dissipation path for the additional current path, thereby further improving the heat resistance and magnetic resistance of the current sensor.

[0017] (7) In the above (5) or (6), it is preferable that the current sensor has a housing that houses the detection conductor and a pair of terminals that are connected to both sides of the detection conductor and protrude to both sides of the housing, the first intersection and the second intersection of the current path and the non-electrically conductive heat transfer member are each formed by a bus bar made of a metal flat plate, the base end of each of the first intersection and the second intersection is fastened to the pair of terminals of the current sensor, and the non-electrically conductive heat transfer member is fastened to the terminal together with the base end of at least one of the first intersection and the second intersection. Since the current sensor has a pair of terminals on both sides of the housing that houses the detection conductor, the current path extending to one side and the other side in the plate thickness direction of the detection conductor can be easily and easily assembled by simply fastening the first intersection and the second intersection of the current path formed by the bus bar to the pair of terminals. Furthermore, by simply fastening a non-electrically conducting heat transfer member consisting of a bus bar to at least one of the terminal portions together with the first intersection portion and / or the second intersection portion, a heat dissipation path for the electric current path can be easily and efficiently configured near the current sensor.

[0018] (8) In any one of the above (1) to (3), (5) and (6), it is preferable that the non-electrically conductive heat transfer member is branched off from a part of the electric current path and provided integrally with the electric current path. By branching off a part of the electric current path and providing the non-electrically conductive heat transfer member integrally with the electric current path, it is possible to reduce the number of parts and simplify the manufacturing process.

[0019] (9) In any one of the above (1) to (8), it is preferable that the device further includes a case that houses the current sensor, the electric path, and the non-electrically conductive heat transfer member, the case constitutes the heat dissipation target, and the heat transfer part of the non-electrically conductive heat transfer member is in contact with the case so as to be capable of thermal conduction. By using the case of the circuit unit as the heat dissipation target, the heat transfer part of the non-electrically conductive heat transfer member can be brought into contact with the heat dissipation target in the vicinity of the current sensor, which is expected to reduce the size of the non-electrically conductive heat transfer member and dissipate heat more quickly in the electric path.

[0020] <Details of the embodiment of the present disclosure> Specific examples of the circuit unit 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 of the claims.

[0021] <Embodiment 1> A circuit unit 10 according to a first embodiment of the present disclosure will be described below with reference to Figures 1 and 2. The circuit unit 10 is mounted on a vehicle (not shown), such as an electric vehicle or a hybrid vehicle, and supplies and controls electric power from a power source (not shown), such as a battery, to a load (not shown), such as a motor. The circuit unit 10 can be arranged in any orientation, but for convenience, the following description will use the arrows in Figure 1 as up, down, left, right, front, and rear.

[0022] 1 and 2, the circuit unit 10 has a structure in which a current sensor 12, an electric current path 16 including a detection conductor 14 whose current value is detected by the current sensor 12, and non-electrically conductive heat transfer members 20a, 20b including heat transfer portions 18a, 18b that are thermally connected to the electric current path 16 and are in thermally conductive contact with a heat dissipation target (a bottom wall 26 of a first case member 22 described later) are housed in a case 24 including a first case member 22. Although not shown, the first case member 22 is combined with a second case member (not shown) to form a case 24 that defines an accommodation space therein. The second case member may house and hold electrical components such as relays and fuses (not shown) to which the electric current path 16 is conductively connected, as well as connectors.

[0023] <First case member 22> The first case member 22 is formed by injection molding an insulating synthetic resin into a predetermined shape. The synthetic resin constituting the first case member 22 may contain a filler such as glass fiber. As shown in FIG. 1, the first case member 22 has a generally rectangular box shape that opens upward as a whole, and has a bottom wall 26 and a peripheral wall 28 that protrudes upward from an edge of the bottom wall 26. In the first embodiment of the present disclosure, the outer shape of the first case member 22 is generally rectangular when viewed from above. The shape of the first case member 22 is not limited to that of the first embodiment.

[0024] As shown in Figs. 1 and 2, a pair of support bases 30a, 30b are protrudingly provided at the right end of the bottom wall 26 of the first case member 22, with a gap between them in the left-right direction. The pair of support bases 30a, 30b have the same rectangular cross section and extend in the front-rear direction. Nut accommodating sections 32a, 32b that open upward are provided in the center portions of the pair of support bases 30a, 30b in the front-rear direction, and nuts 34a, 34b are accommodated therein. A current sensor accommodating section 36 that is concave and opens upward is provided between the pair of support bases 30a, 30b.

[0025] <Current sensor 12> As shown in FIG. 2, the current sensor 12 includes a housing 38 that houses the detection conductor 14 that constitutes a part of the electric current path 16 and detects a current value by the current sensor 12, and a pair of terminals 40a, 40b that are connected to both sides in the extension direction (left and right direction in FIG. 2) of the detection conductor 14 and protrude to both sides in the left and right direction of the housing 38. The pair of terminals 40a, 40b are respectively provided with bolt insertion holes 41a, 41b through which fastening bolts 60a, 60b described later are inserted. The current sensor 12 also includes a magnetic detection unit 42 that is placed on the detection conductor 14 housed inside the housing 38 and detects a magnetic field corresponding to the current flowing through the detection conductor 14. Although not shown, an output signal detected by the magnetic detection unit 42 is sent to an external electric control device or the like via an electric wire connected to the magnetic detection unit 42. The current sensor 12 of this embodiment is of a magnetic field detection type.

[0026] The pair of terminals 40a, 40b of the current sensor 12 are supported by being overlapped on the upper surfaces of the pair of support bases 30a, 30b of the first case member 22. At this time, the bolt insertion holes 41a, 41b provided in the pair of terminals 40a, 40b are aligned approximately coaxially with the nut accommodating portions 32a, 32b opening on the upper surfaces of the pair of support bases 30a, 30b. In this state, the housing 38 of the current sensor 12 is disposed with a part of it accommodated in the current sensor accommodating portion 36 provided between the pair of support bases 30a, 30b.

[0027] <Electrical path 16> The electric path 16, which is the object of current detection, has a pair of parallel parts 44a, 44b connected to the detection conductor 14 housed in the housing 38 of the current sensor 12 and a pair of terminal parts 40a, 40b of the current sensor 12, and extends in a direction away from the current sensor 12 in a state parallel to the detection conductor 14 from both sides in the extension direction of the detection conductor 14. The pair of parallel parts 44a, 44b are each formed of a bus bar formed by press-punching a metal plate into a predetermined shape. The base ends 46a, 46b of the pair of parallel parts 44a, 44b, which are the ends on the current sensor 12 side, are provided with bolt insertion holes 48a, 48b through which fastening bolts 60a, 60b, which will be described later, are inserted (see FIG. 2). Bolt insertion holes 52a, 52b used for fastening to other members (not shown) are also formed through protruding ends 50a, 50b which are ends of the pair of parallel portions 44a, 44b that are away from the current sensor 12.

[0028] The base ends 46a, 46b of the pair of parallel portions 44a, 44b are respectively placed on the upper surfaces of the pair of terminal portions 40a, 40b of the current sensor 12. At this time, the bolt insertion holes 48a, 48b provided in the base ends 46a, 46b are aligned substantially coaxially with the bolt insertion holes 41a, 41b of the pair of terminal portions 40a, 40b and the nut accommodating portions 32a, 32b.

[0029] <Non-electrically-conductive heat-transfer members 20a, 20b> A pair of non-electrically conductive heat transfer members 20a, 20b are thermally connected to the base ends 46a, 46b of the pair of parallel parts 44a, 44b constituting the electric path 16. Specifically, the pair of non-electrically conductive heat transfer members 20a, 20b are configured by bus bars formed by press-punching a metal plate into a predetermined shape. In the first embodiment, the pair of non-electrically conductive heat transfer members 20a, 20b have fastening parts 54a, 54b at one end in the length direction, which are fastened to the pair of terminal parts 40a, 40b of the current sensor 12 together with the base ends 46a, 46b of the pair of parallel parts 44a, 44b. At the other end in the length direction of the pair of non-electrically conductive heat transfer members 20a, 20b, heat transfer parts 18a, 18b are provided, which are in contact with the first case member 22 (case 24) to be dissipated heat in a heat-conductive manner. The fastening portions 54a, 54b of the pair of electrically non-conductive heat transfer members 20a, 20b are provided with bolt insertion holes 56a, 56b through which fastening bolts 60a, 60b, which will be described later, are inserted (see FIG. 2).

[0030] 2, the pair of non-electrically conducting heat transfer members 20a, 20b are formed in a crank shape in which the fastening parts 54a, 54b and the heat transfer parts 18a, 18b on both sides in the length direction extend parallel to the detection conductor 14, and the intermediate region therebetween extends perpendicular to the extension direction of the detection conductor 14. The fastening parts 54a, 54b of the pair of non-electrically conducting heat transfer members 20a, 20b are respectively superimposed on the lower surfaces of the pair of terminal parts 40a, 40b of the current sensor 12. At this time, the bolt insertion holes 56a, 56b provided in the fastening parts 54a, 54b are aligned approximately coaxially with the bolt insertion holes 48a, 48b of the parallel parts 44a, 44b, the bolt insertion holes 41a, 41b of the pair of terminal parts 40a, 40b, and the nut accommodating parts 32a, 32b. In addition, the pair of non-electrically conducting heat transfer members 20a, 20b are arranged in an axisymmetrical orientation in the longitudinal cross-sectional view (or projection in the front-to-rear direction) shown in Figure 2 so that their intermediate regions and heat transfer portions 18a, 18b are respectively accommodated within the current sensor accommodating portion 36.

[0031] In the first embodiment, the pair of non-electrically conducting heat transfer members 20a, 20b are fastened and thermally connected to the electric path 16 at the respective base ends 46a, 46b of the pair of parallel parts 44a, 44b extending from both sides of the detection conductor 14, but the present invention is not limited thereto, and one of the non-electrically conducting heat transfer members 20a or 20b may be thermally connected to the base end 46a or 46b of one of the parallel parts 44a or 44b. Specifically, the base end 46a or 46b of one of the parallel parts 44a or 44b may be fastened to one of the terminal parts 40a or 40b of the current sensor 12 together with one of the non-electrically conducting heat transfer members 20a or 20b by a fastening bolt 60a or 60b described later.

[0032] The heat transfer parts 18a, 18b of the pair of non-electrically conducting heat transfer members 20a, 20b are in thermally conductive contact with the bottom wall 26 of the first case member 22 constituting the bottom of the current sensor housing 36 via the heat conductive members 58a, 58b. That is, the heat transfer parts 18a, 18b of the non-electrically conducting heat transfer members 20a, 20b are in thermal contact with the heat dissipation target (the bottom wall 26 of the first case member 22) on the current sensor 12 side from the protruding ends 50a, 50b of the parallel parts 44a, 44b via the heat conductive members 58a, 58b. The heat conductive members 58a, 58b are both in the form of a flat sheet having insulating properties, and are made of synthetic resin having a higher thermal conductivity than air. Specifically, silicone-based resin, non-silicone-based acrylic resin, ceramic resin, etc. can be used. More specifically, examples of the heat dissipation gap filler, heat conductive grease, heat conductive silicone rubber, etc., made of silicone-based resin, can be mentioned. The heat conductive members 58a, 58b are flexible and can change their thickness depending on the force applied in the vertical direction. In the first embodiment, the heat conductive members 58a, 58b are both sheet-shaped, but are not limited to this and can be of any shape. As is clear from the above-mentioned structure, the pair of non-electrically conductive heat transfer members 20a, 20b are thermally connected to the electric path 16 at the fastening parts 54a, 54b, but the other parts are not connected to the electric path 16 or other electric members, so they are non-electrically conductive members.

[0033] <Assembly process of the circuit unit 10> Next, a description will be given of an example of an assembly process for the circuit unit 10. The assembly process for the circuit unit 10 is not limited to the following description.

[0034] First, the first case member 22 constituting the case 24 is prepared. Next, two heat conductive members 58a, 58b are cut into a predetermined shape by a known method such as Thompson die cutting. The heat conductive members 58a, 58b thus formed are placed at predetermined positions on the bottom of the current sensor housing 36.

[0035] Next, the pair of parallel portions 44a, 44b and the pair of non-electrically conducting heat transfer members 20a, 20b are prepared by press-punching the metal plate into a predetermined shape. The pair of non-electrically conducting heat transfer members 20a, 20b are oriented so that their intermediate regions and heat transfer portions 18a, 18b are respectively accommodated in the current sensor accommodating portion 36, and the fastening portions 54a, 54b of the pair of non-electrically conducting heat transfer members 20a, 20b are placed on the upper surfaces of the pair of supports 30a, 30b with their respective bolt insertion holes 56a, 56b aligned approximately coaxially with the nut accommodating portions 32a, 32b.

[0036] Thereafter, the pair of terminal portions 40a, 40b of the current sensor 12, which has been separately prepared, are placed on the fastening portions 54a, 54b of the pair of non-electrically conducting heat transfer members 20a, 20b in a state in which the bolt insertion holes 41a, 41b are aligned approximately coaxially with the bolt insertion holes 56a, 56b and the nut accommodating portions 32a, 32b. Next, the pair of parallel portions 44a, 44b are arranged in their respective wiring locations, and the pair of terminal portions 40a, 40b of the current sensor 12 are placed on the upper surfaces of the pair of terminal portions 40a, 40b in a state in which the bolt insertion holes 48a, 48b of the pair of parallel portions 44a, 44b are aligned approximately coaxially with the bolt insertion holes 41a, 41b, the bolt insertion holes 56a, 56b, and the nut accommodating portions 32a, 32b. Finally, the separately prepared fastening bolts 60a, 60b are inserted through the bolt insertion holes 48a, 48b, the bolt insertion holes 41a, 41b, and the bolt insertion holes 56a, 56b in order into the nut accommodating parts 32a, 32b, and fastened to the nuts 34a, 34b accommodated in the nut accommodating parts 32a, 32b. As a result, the base ends 46a, 46b of the parallel parts 44a, 44b are fastened to the terminal parts 40a, 40b of the current sensor 12 together with the fastening parts 54a, 54b of the non-electrically conductive heat transfer members 20a, 20b by the fastening bolts 60a, 60b. Then, the first case member 22 to which the current sensor 12, the electric path 16 including the detection conductor 14, and the non-electrically conductive heat transfer members 20a, 20b having the heat transfer parts 18a, 18b are assembled is completed. In response to this, a second case member (not shown) that houses and holds electrical components such as relays, fuses, and connectors (not shown) is combined to form a case 24 inside which the electrical components, etc. are housed, and the circuit unit 10 is completed.

[0037] Next, the operation and effect of the circuit unit 10 of the first embodiment will be described. According to the first embodiment, the pair of non-electrically conducting heat transfer members 20a, 20b are thermally connected to the electric path 16 including the detection conductor 14 sensed by the current sensor 12 and the pair of parallel parts 44a, 44b. That is, the fastening parts 54a, 54b of the pair of non-electrically conducting heat transfer members 20a, 20b are fastened to the terminal parts 40a, 40b of the current sensor 12 together with the base ends 46a, 46b of the parallel parts 44a, 44b, so that the pair of non-electrically conducting heat transfer members 20a, 20b are thermally connected to the electric path 16. The heat transfer parts 18a, 18b provided on the pair of non-electrically conducting heat transfer members 20a, 20b are in contact with the bottom wall 26 of the first case member 22, which is the heat dissipation target, in a manner that allows heat conduction. As a result, the non-electrically conducting heat transfer members 20a, 20b are disposed in a region separate from the wiring path of the electric current path 16, and a heat dissipation path of the electric current path 16 can be efficiently secured in space via the non-electrically conducting heat transfer members 20a, 20b. Moreover, since the non-electrically conducting heat transfer members 20a, 20b are non-conductive, no magnetic field is generated due to current flow, and the influence of the non-electrically conducting heat transfer members 20a, 20b on the magnetic field of the current sensor 12 is advantageously avoided or suppressed. As a result, even when a large current flows through the electric current path 16, the heat dissipation of the electric current path 16 can be promoted to suppress the thermal influence on the current sensor 12, and further, even if the heat dissipation path by the non-electrically conducting heat transfer members 20a, 20b is used, the influence on the magnetic field of the current sensor 12 can be suppressed.

[0038] In particular, in this embodiment, since the current path 16 has a pair of parallel parts 44a, 44b extending parallel to the detection conductor 14 from both sides in the extension direction of the detection conductor 14, it is advantageously possible to avoid forming a current-carrying area extending in the same direction in a direction intersecting the detection conductor 14 near the detection conductor 14. As a result, it is possible to advantageously suppress the generation of noise accompanying magnetic field coupling due to the current path near the current sensor 12, and improve the magnetic resistance of the current sensor.

[0039] In addition, since the non-electrically conducting heat transfer members 20a, 20b are fastened together to the base ends 46a, 46b of the parallel portions 44a, 44b and thermally connected to the electric path 16, a heat dissipation path for the electric path 16 can be secured in the vicinity of the current sensor 12, and the heat resistance of the current sensor 12 can be improved. In particular, by using the first case member 22 constituting the case 24 of the circuit unit 10 as the heat dissipation target, the heat transfer portions 18a, 18b of the non-electrically conducting heat transfer members 20a, 20b can be brought into contact with the heat dissipation target in the vicinity of the current sensor 12, and it is expected that the non-electrically conducting heat transfer members 20a, 20b can be made smaller and the heat can be dissipated more quickly in the electric path 16.

[0040] Furthermore, the heat transfer portions 18a, 18b of the non-electrically conducting heat transfer members 20a, 20b are in contact with the bottom wall 26 of the first case member 22, which is the heat dissipation target, on the side closer to the current sensor 12 than the protruding ends 50a, 50b of the parallel portions 44a, 44b to which they are connected. This allows heat to be dissipated quickly near the current sensor 12 via the non-electrically conducting heat transfer members 20a, 20b of the electric path 16, and further improves the heat resistance and magnetic resistance of the current sensor 12.

[0041] In addition, the current sensor 12 has a pair of terminals 40a, 40b on both sides (both sides in the extending direction of the detection conductor 14) of the housing 38 that houses the detection conductor 14. Therefore, by simply fastening the pair of parallel parts 44a, 44b formed of bus bars to the pair of terminal parts 40a, 40b, the current path 16 in which the pair of parallel parts 44a, 44b protrude on both sides of the detection conductor 14 can be configured easily and with good assembly workability. Furthermore, by simply fastening the pair of non-current-carrying heat transfer members 20a, 20b formed of bus bars to the respective terminal parts 40a, 40b together with the respective parallel parts 44a, 44b, a heat dissipation path of the current path 16 can be configured easily and with good assembly workability near the current sensor 12.

[0042] <Embodiment 2> A second embodiment in which the technology disclosed in this specification is applied to a circuit unit 70 will be described with reference to Figs. 3 and 4. The circuit unit 70 of the second embodiment has a structure similar to that of the circuit unit 10 of the first embodiment as a whole, but differs from the circuit unit 10 in the layout shape of the current path 72 and in that the current path 72 is provided with a current-side heat transfer portion that is in contact with a heat dissipation target so as to be capable of thermal conduction, as shown in Fig. 4. In the second embodiment, the same members and parts as those of the first embodiment are denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted.

[0043] 3 and 4, in the circuit unit 70, a first intersection 74 and a second intersection 76 each formed of a bus bar made of a metal flat plate are connected to a pair of terminals 40a and 40b of the current sensor 12 instead of the pair of parallel parts 44a and 44b. That is, in the circuit unit 70, the current path 72 is configured to include the detection conductor 14, the first intersection 74 protruding from one end side (left side in FIG. 4) of the detection conductor 14 to one side (upper side in FIG. 4) in the plate thickness direction of the detection conductor 14, and the second intersection 76 protruding from the other end side (right side in FIG. 4) of the detection conductor 14 to the other side (lower side in FIG. 4) in the plate thickness direction of the detection conductor 14. In the circuit unit 70, the fastening portion 54a of the non-electrically conducting heat transfer member 20a, together with the base end portion 78 of the first intersecting portion 74, is thermally connected to the electric path 72 on the side of the base end portion 78 of the first intersecting portion 74. Specifically, the base ends 78, 79 of the first intersecting portion 74 and the second intersecting portion 76 are fastened to the terminal portions 40a, 40b of the electric current sensor 12 by the fastening bolts 60a, 60b, respectively. The non-electrically conducting heat transfer member 20a, together with the base end portion 78 of the first intersecting portion 74, is fastened to the terminal portion 40a of the electric current sensor 12. The heat transfer portion 18a of the non-electrically conducting heat transfer member 20a is in contact with the bottom wall 26 of the first case member 22 constituting the case 24 via the heat conductive member 58a in a thermally conductive manner, as in the first embodiment. As a result, a first heat dissipation path of the electric path 72 is secured in the vicinity of the current sensor 12 (on the side of the terminal portion 40a).

[0044] In the circuit unit 70, although the non-current-carrying heat transfer member 20b is not provided on the second intersection 76 side, the second intersection 76 has a current-carrying heat transfer portion 82 that is in thermally conductive contact with the bottom wall 26 of the first case member 22, which is the heat dissipation target, via a heat conductive member 80 (see FIG. 4). This ensures that the second discharge path of the current path 72 is in the vicinity of the current sensor 12 (on the terminal portion 40b side). Note that any of the heat conductive members 58a and 58b exemplified above can be used as the heat conductive member 80.

[0045] In the circuit unit 70 having such a structure, the current path 72 has the first intersection 74 and the second intersection 76 that protrude from both sides of the extension direction of the detection conductor 14 to one side and the other side in the plate thickness direction of the detection conductor 14, so that the magnetic fields generated by the first intersection 74 and the second intersection 76 in the vicinity of the detection conductor 14 cancel each other out. This makes it possible to advantageously suppress the generation of noise associated with magnetic field coupling by the current path 72 in the vicinity of the current sensor 12, and improve the magnetic resistance of the current sensor 12. Furthermore, since the heat dissipation path of the current path 72 on the first intersection 74 side using the non-current-conducting heat transfer member 20a and the heat dissipation path from the current-conducting heat transfer part 82 provided at the second intersection 76 to the first case member 22 are secured, the heat resistance of the current sensor 12 can also be improved.

[0046] In the circuit unit 70, the current sensor 12 has a pair of terminal portions 40a, 40b on both sides of the housing 38 that houses the detection conductor 14, so that the current path 72 extending to one side and the other side in the plate thickness direction of the detection conductor 14 can be easily and efficiently assembled by simply fastening the first intersection portion 74 and the second intersection portion 76 formed of a bus bar to the pair of terminal portions 40a, 40b. Furthermore, a heat dissipation path in the current path 72 in the vicinity of the current sensor 12 can be easily and efficiently assembled by simply fastening the non-current-carrying heat transfer member 20a formed of a bus bar to the terminal portion 40a together with the first intersection portion 74.

[0047] <Modification> Although the first and second embodiments have been described above as specific examples of the present disclosure, the present disclosure is not limited to these specific descriptions. Modifications, improvements, etc. within the scope of the present disclosure that can achieve the object of the present disclosure are included in the present disclosure. For example, the following modified examples of the embodiments are also included in the technical scope of the present disclosure.

[0048] (1) In the first and second embodiments, the current paths 16, 72 and the non-electrically conductive heat transfer members 20a, 20b are formed by fastening the separate parallel parts 44a, 44b or the first and second intersecting parts 74, 76 formed by the bus bar to the terminal parts 40a, 40b of the current sensor 12, but the present invention is not limited thereto. For example, as shown in a model diagram in FIG. 5, the current path 84 may be formed by one continuous bus bar, and a separate current sensor 86 may be assembled to the current path 84. In addition, the non-electrically conductive heat transfer member 88 may be provided integrally by branching off from a part of the current path 84, and may have a heat transfer part 90 at its end. This can reduce the number of parts and simplify the manufacturing process.

[0049] (2) In embodiment 1, the non-electrically conductive heat transfer members 20a, 20b are thermally connected to both of the pair of parallel portions 44a, 44b of the electric current path 16. However, the number of non-electrically conductive heat transfer members may be one or three or more.

[0050] (3) In the second embodiment, the non-electrically conducting heat transfer member 20a is thermally connected only to the first intersection 74 of the electric current path 72. However, instead of or in addition to the first intersection 74, the non-electrically conducting heat transfer member 20b may be thermally connected to the second intersection 76. Specifically, for example, the non-electrically conducting heat transfer members 20a, 20b may be fastened to the terminal portions 40a, 40b of the current sensor 12 together with the base ends 78, 79 of the first and second intersections 74, 76. In addition, in the second embodiment, the electric current side heat transfer portion 82 is provided only at the second intersection 76. However, instead of or in addition to the second intersection 76, the electric current side heat transfer portion 82 may be provided at the first intersection 74.

[0051] (4) The heat dissipation target was case 24 of the circuit unit, but heat transfer sections 18a, 18b and current-carrying side heat transfer section 82 may be in thermally conductive contact with a heat dissipation target outside the case (such as a metal casing of another component) through an opening provided in case 24. [Explanation of symbols]

[0052] 10 Circuit unit (embodiment 1) 12 Current Sensor 14 Detecting conductor part 16 Current-carrying path 18a, 18b Heat transfer section 20a, 20b Non-conductive heat transfer member 22 First case member 24 cases 26 Bottom wall (heat dissipation target) 28 Peripheral wall 30a, 30b A pair of support bases 32a, 32b Nut receiving section 34a, 34b Nut 36 Current sensor housing 38 Housing (current sensor) 40a,40b terminal section 41a, 41b Bolt insertion hole (terminal part) 42 Magnetic detection unit 44a, 44b Parallel section 46a,46b Base end 48a, 48b Bolt insertion hole (parallel part) 50a,50b Projecting end 52a, 52b Bolt insertion holes 54a, 54b Fastening parts 56a, 56b Bolt insertion hole (non-electrically conductive heat transfer member) 58a, 58b Thermal conductive member 60a, 60b Fastening bolt 70 Circuit unit (embodiment 2) 72 Current-carrying path 74 First Intersection 76 Second Intersection 78,79 Proximal end 80 Thermal Conductive Materials 82 Current-carrying heat transfer section 84 Current-carrying circuit (variation) 86 Current sensor (modification) 88 Non-electrically conductive heat transfer member (modified version) 90 Heat transfer section (variation)

Claims

1. A current sensor; an electric current path including a detection conductor portion whose current value is detected by the current sensor; and a non-electrically conductive heat transfer member including a heat transfer portion that is thermally connected to the electric current path and in contact with a heat dissipation target so as to be capable of thermal conduction. Circuit unit.

2. the current path has a pair of parallel portions extending from both sides of the detection conductor in an extending direction in a direction away from the current sensor in parallel with the detection conductor, The circuit unit according to claim 1 , wherein the non-electrically conductive heat transfer member is thermally connected to the electric path on a base end side of at least one of the parallel portions.

3. 3 . The circuit unit according to claim 2 , wherein the heat transfer portion of the non-electrically conducting heat transfer member is in contact with the heat dissipation target on a side closer to the current sensor than the protruding end of the parallel portion.

4. The current sensor includes a housing that houses the detection conductor and a pair of terminals that are connected to both sides of the detection conductor and protrude to both sides of the housing, each of the parallel portions of the electric current path and the non-electrically conductive heat transfer member is formed of a bus bar made of a metal flat plate, 4. The circuit unit according to claim 2, wherein the base ends of the parallel portions are fastened to a pair of terminal portions of the current sensor, and the non-electrically conductive heat transfer member is fastened to the terminal portions together with the base ends of at least one of the parallel portions.

5. The current path has a first intersecting portion protruding from one end side of the detection conductor to one side in the plate thickness direction of the detection conductor, and a second intersecting portion protruding from the other end side of the detection conductor to the other side in the plate thickness direction of the detection conductor, The circuit unit according to claim 1 , wherein the non-electrically conductive heat transfer member is thermally connected to the electric path on a base end side of at least one of the first intersecting portion and the second intersecting portion.

6. The circuit unit according to claim 5 , wherein at least one of the first intersection portion and the second intersection portion is provided with a current-carrying heat transfer portion that is in thermally conductive contact with the heat dissipation target.

7. The current sensor has a housing that houses the detection conductor and a pair of terminals that are connected to both sides of the detection conductor in an extension direction and protrude to both sides of the housing, the first intersection portion and the second intersection portion of the current-carrying path and the non-current-carrying heat-transfer member are each formed of a bus bar made of a metal flat plate, The circuit unit described in claim 5 or claim 6, wherein the base end of each of the first intersection portion and the second intersection portion is fastened to a pair of terminal portions of the current sensor, and the non-electrically conductive heat transfer member is fastened to the terminal portions together with the base end of at least one of the first intersection portion and the second intersection portion.

8. The circuit unit according to claim 1 , wherein the non-electrically conductive heat transfer member is branched off from a portion of the electric current path and is provided integrally therewith.

9. a case that accommodates the current sensor, the current path, and the non-current-conducting heat transfer member, the case configuring the heat dissipation target; 3. The circuit unit according to claim 1, wherein the heat transfer portion of the non-electrically conducting heat transfer member is in thermally conductive contact with the case.

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