JP5565608B2 - Circuit unit - Google Patents

Description

  The present invention relates to a circuit unit in which a circuit board is accommodated in a case.

  As a circuit unit in which a circuit board is accommodated in a case, for example, the one described in Patent Document 1 is known.

JP 7-176875 A

  In recent years, miniaturization of circuit units has been required. However, when a reduction in size is required, it may be required to reduce the volume of the case while maintaining the conventional scale of the circuit. For this reason, there exists a problem that the heat generation density of the electronic component etc. which were mounted in the circuit board will become larger than before.

  In the prior art, since there is a gap between the circuit board and the case, an air layer is formed in this gap. Since air has a relatively low thermal conductivity, heat is trapped in the air layer, and as a result, there is a concern that heat may be trapped in the case. Then, for example, there is a concern that the temperature of the solder portion between the conductive path of the circuit board and the terminal of the electronic component rises, and the electrical connection reliability decreases. In addition, there is a possibility that a malfunction such as malfunction occurs in the electronic component.

  This invention is completed based on the above situations, Comprising: It aims at providing the circuit unit by which heat was suppressed in the case.

The present invention is a circuit unit having a case in which an opening provided on one end surface is closed by a lid, and a first circuit board accommodated in the case, wherein the case includes: A heat-dissipating wall that has a wall surface parallel to the opening direction of the opening and receives heat generated in the first circuit board when energized and dissipates it to the outside of the case; and an opposing wall that faces the heat-dissipating wall. The first circuit board is accommodated in the case in such a manner that the plate surface of the first circuit board is along the wall surface of the heat radiating wall, and the first circuit board faces the first circuit board in the case. A holding member for holding the first circuit board located on the wall side is housed, and the holding member is provided on the first circuit board and an abutting portion that abuts against the opposing wall from the inside of the case. The first circuit board in contact with the inside of the case Wherein a pressing portion for pressing the heat radiation wall, have a, in the above case, the being the second circuit board disposed on the opposite wall side of the holding member is accommodated, said holding member, A heat shield wall that shields heat between the first circuit board and the second circuit board is provided .

According to the present invention, the first circuit board is pressed against the heat radiation wall by the pressing portion of the holding member. Thereby, it can suppress that a clearance gap arises between a 1st circuit board and a thermal radiation wall, and an air layer is formed. As a result, the heat generated in the first circuit board during energization is quickly transmitted from the first circuit board to the heat radiating wall, and is dissipated from the heat radiating wall to the outside of the case. Thus, according to this invention, it can suppress that an air layer intervenes in the heat-transfer path | route from an electronic component to a thermal radiation wall. In other words, no air layer is interposed, or the air layer can be reduced. Thereby, since heat conductivity from an electronic component to a heat radiating wall can be improved, it can suppress that heat is trapped in a case.
Moreover, according to said aspect, it can suppress that the heat | fever generate | occur | produced by one side of the 1st circuit board and the 2nd circuit board at the time of electricity supply is transmitted to the other. As a result, it is possible to suppress the occurrence of a malfunction such as a malfunction in the electronic component mounted on one of the first circuit board and the second circuit board due to the heat generated from the other circuit board. This aspect is effective when an electronic component that generates heat when energized is mounted on one of the first circuit board and the second circuit board, and an electronic component that is relatively weak against heat is mounted on the other. .

As embodiments of the present invention, the following embodiments are preferable.
Both or one of the heat radiating wall and the opposing wall are formed in a shape bent inward of the case before the first circuit board and the holding member are accommodated in the case. It is preferable.

  According to the above aspect, when the holding member and the first circuit board are accommodated in the case, the holding member and the first circuit board are sandwiched between the heat dissipation wall and the opposing wall. As a result, the contact portion of the holding member receives pressure from the opposing wall, and the first circuit board is pressed against the heat radiating wall by the pressing portion receiving the pressure. Thereby, compared with the case where the heat radiating wall and the opposing wall are not bent inward of the case, the first circuit board can be securely adhered to the heat radiating wall. Thereby, it can further suppress that heat is trapped in the case.

  Preferably, the first circuit board has a rectangular shape, and the pressing portion is provided so as to press a substantially central portion in the longitudinal direction of the first circuit board.

  When heat is generated in the first circuit board and the temperature of the first circuit board rises, the first circuit board extends in a direction parallel to the plate surface. However, since the first circuit board is accommodated in the case, the edge of the first circuit board extending in the direction parallel to the plate surface abuts on the inner wall of the case, and the first circuit board has a longitudinal direction. There is a concern that the vicinity of the center bends away from the heat radiating wall.

  According to said aspect, since a press part is provided so that the substantially center part of the longitudinal direction of the 1st circuit board which is easy to produce a clearance gap may be pressed, a clearance gap arises between a 1st circuit board and a thermal radiation wall. This can be further suppressed. Thereby, it can further suppress that heat is trapped in the case.

A space is formed between the first circuit board and the holding member, and a heat radiating window that exposes the inner wall of the case is opened in the space of the holding member facing the case. Are preferably provided.

  According to the above aspect, the heat generated in the first circuit board during energization is dissipated in the space surrounded by the holding member and the first circuit board, and then transferred to the inner wall of the case exposed in the heat dissipation window. Is done. Thereafter, heat is dissipated from the case to the outside. Thereby, it can further suppress that heat is trapped in the case.

  According to the present invention, it is possible to prevent heat from being trapped in the case of the circuit unit.

The perspective view which shows the electric junction box which concerns on one Embodiment of this invention. Exploded perspective view showing electrical junction box The perspective view which shows the electrical-connection box shown from the direction different from FIG. FIG. 2 is an exploded perspective view showing the electrical junction box, viewed from a direction different from FIG. Sectional view showing the electrical junction box Sectional drawing which shows the electrical junction box cut | disconnected in the cross section different from FIG. Flat cross section showing electrical junction box Plan view showing the first circuit board The perspective view which shows a 1st circuit board The perspective view which shows the state which connected the connection board to the 1st circuit board The perspective view which shows a holding member The perspective view which shows the state which assembled | attached the 1st circuit board to the holding member. The perspective view shown from a different direction about FIG. The top view which shows the state which attached the 2nd circuit board to the holding member The perspective view which shows the state which attached the 2nd circuit board to the holding member. The perspective view shown from a different direction about FIG. The side view which shows the state which attached the 1st circuit board and the 2nd circuit board to the holding member FIG. 17 is a side view showing from a different direction. The rear view which shows the state which attached the 1st circuit board and the 2nd circuit board to the holding member Sectional drawing which shows the state which attached the 1st circuit board and the 2nd circuit board to the holding member The perspective view which shows the state in which the cover part was attached to the holding member The perspective view shown from a different direction about FIG. Front view of the case Sectional drawing which shows the state in which the 1st circuit board, the 2nd circuit board, and the holding member were accommodated in the case

  An embodiment in which the present invention is applied to an in-vehicle electrical junction box 10 (corresponding to a circuit unit described in claims) will be described with reference to FIGS. The electrical junction box 10 is connected between a power source (not shown) such as a battery and vehicle electrical components (not shown) such as a headlamp and a wiper, and executes switching of various vehicle electrical components. The electrical junction box 10 according to this embodiment includes a case 11 and a first circuit board 12 and a second circuit board 13 accommodated in the case 11. The electric junction box 10 can be attached to the vehicle in any posture.

(Case 11)
The case 11 is made of synthetic resin and has a flat rectangular parallelepiped shape as a whole. As shown in FIG. 2, an opening 14 is formed on one end surface of the case 11 (the end surface on the left front side in FIG. 2). A synthetic resin lid 15 is attached to the opening 14 of the case 11, and the opening 14 is closed by the lid 15. A first lock protrusion 16 that protrudes outward is formed on the outer surface of the lid portion 15. A first lock receiving portion 17 is formed at a position corresponding to the first lock protrusion 16 in the case 11. The first lock receiving portion 17 is elastically engaged with the first lock protrusion 16 so that the lid portion 15 and the case 11 are assembled together.

  The lid 15 is formed with a fitting portion 18 that can be connected to a mating connector (not shown) that opens outward (toward the left front side in FIG. 2). The mating connector is connected to the in-vehicle electrical component via an electric wire (not shown). As shown in FIG. 5, one end of the connector terminal 19 is positioned and arranged inside the fitting portion 18. The other end of the connector terminal 19 passes through the lid 15 and is introduced into the case 11.

  As shown in FIG. 5, a synthetic resin wire cover 20 is attached to the end edge of the case 11 on the side where the opening 14 is formed to cover the wire led out from the mating connector. A plurality of second lock protrusions 21 protruding outward are formed on the outer surface of the case 11, and a plurality of second lock receiving portions 22 are formed at corresponding positions of the wire cover 20. The electric wire cover 20 is assembled to the case 11 by the second lock receiving portion 22 being elastically engaged with the second lock protrusion 21.

  Further, as shown in FIG. 4, a plurality of third lock protrusions 41 protruding outward are formed on the outer surface of the lid portion 15, and a plurality of third lock protrusions 41 are formed at corresponding positions of the wire cover 20. A lock receiving portion 42 is formed. The electric wire cover 20 is assembled to the lid portion 15 by the third lock receiving portion 42 being elastically engaged with the third lock protrusion 41.

  In a state where the wire cover 20 is attached to the case 11, the half lead-out portion 23 </ b> A provided on the side edge on the opening 14 side of the case 11 and the half lead-out portion 23 </ b> B provided on the wire cover 20 are combined. Thus, a lead-out portion 23 for leading the electric wire from the electric wire cover 20 is formed.

(First circuit board 12)
A first circuit board 12 is accommodated in the case 11. The first circuit board 12 has a substantially rectangular shape, and a conductive path is formed by a printed wiring technique. An electronic component 24A that generates heat when energized is mounted on the conductive path. As the electronic component 24, for example, any element such as a relay, a semiconductor switching element, or a fuse can be used as necessary. The first circuit board 12 is made of a fiber base material and a synthetic resin, and is configured to be bendable.

  As shown in FIG. 5, a portion of the first circuit board 12 positioned on the opening 14 side of the case 11 is bent at a substantially right angle to form a connector connection portion 25. The other end of the connector terminal 19 penetrates and is soldered to the connector connecting portion 25. Thereby, the connector terminal 19 and the conductive path of the connector connection part 25 are electrically connected. A part of the connector terminal 19 having a relatively long and narrow shape is attached to the base 26 made of synthetic resin and attached to the connector connecting portion 25. As a result, the alignment of the relatively elongated connector terminal 19 is maintained.

  The first circuit board 12 is accommodated in the case 11 while being held by a synthetic resin holding member 27. As shown in FIG. 11, the holding member 27 has a substantially rectangular parallelepiped shape. As shown in FIG. 12, the upper and lower walls of the holding member 27 in FIG. 12 are set to have approximately the same shape as the portion of the first circuit board 12 that has a substantially rectangular shape. Further, the height dimension in the vertical direction in FIG. 12 of the holding member 27 is set to be substantially the same as the height dimension in the vertical direction in FIG. 12 of the bent connector connection portion 25 in the first circuit board 12. . As shown in FIG. 15, the connector connecting portion 25 is fixed to the holding member 27 with bolts 28.

  A plurality (two in this embodiment) of positioning holes 29 are formed through the first circuit board 12. The holding member 27 is formed with a plurality of (two in this embodiment) positioning projections 30 protruding toward the first circuit board 12 (upward in FIG. 12) at positions corresponding to the positioning holes 29. The first circuit board 12 is positioned with respect to the holding member 27 by inserting the positioning protrusion 30 into the positioning hole 29.

(Second circuit board 13)
As shown in FIG. 5, the second circuit board 13 is accommodated in the case 11 in a posture substantially parallel to the plate surface of the first circuit board 12. Conductive paths are formed on the second circuit board 13 by a printed wiring technique. The second circuit board 13 is fixed to the holding member 27 with bolts 28 while being arranged at a position opposite to the first circuit board 12 with respect to the holding member 27. As shown in FIG. 14, the second circuit board 13 has a substantially rectangular shape and is set slightly smaller than the holding member 27. As shown in FIG. 12, the holding member 27 is formed with a receiving portion 31 for receiving the second circuit board 13.

  As shown in FIG. 5, an electronic component 24 </ b> B such as a microcomputer is mounted on the conductive path of the second circuit board 13. In addition, as shown in FIG. 6, one end of the connector terminal 19 is disposed in the fitting portion 18 of the lid 15, and the other end of the connector terminal 19 is connected to the lid 15. After being penetrated and introduced into the case 11, it is bent toward the second circuit board 13 and penetrated through the second circuit board 13. The other end of the connector terminal 19 is electrically connected to the conductive path of the second circuit board 13 by soldering or the like.

(Connection board 32)
As shown in FIG. 5, a connection substrate 32 is attached to a position of the first circuit board 12 and the second circuit board 13 that is closer to the end located on the side opposite to the opening 14 of the case 11. . The connection substrate 32 is made of a synthetic resin and has a foldable configuration such as a so-called FPC. The connection board 32 is arranged along the back wall 33 located on the opposite side of the opening 14 in the case 11, and the upper and lower ends in FIG. 5 are along the first circuit board 12 and the second circuit board 13. It is bent. The bent portions of the connection board 32 are connected to the first circuit board 12 and the second circuit board 13, respectively. A conductive path is formed in the connection substrate 32, and the conductive path is connected to the conductive paths formed in the first circuit board 12 and the second circuit board 13. The second circuit board 13 is electrically connected.

(Holding member 27)
The holding member 27 is made of a synthetic resin and has a substantially rectangular parallelepiped shape. As shown in FIG. 7, at the end of the holding member 27 opposite to the opening 14 of the case 11, there is a back wall contact portion 34 that comes into contact with the back wall 33 of the case 11 from the inside of the case 11. , Projecting toward the back wall 33 side. Further, the end portion of the holding member 27 located on the opening 14 side of the case 11 contacts the connector connecting portion 25 of the first circuit board 12 when the mating connector is fitted in the fitting portion 18. Thus, the force applied to the connector terminal 19 when the mating connector is fitted is transmitted to the holding member 27 via the connector connecting portion 25. The force transmitted to the holding member 27 is transmitted to the case 11 via the back wall contact portion 34. Thus, in the present embodiment, the case 11 can receive the force applied to the connector terminal 19 when the mating connector is fitted.

  As shown in FIGS. 4 and 5, the holding member 27 is formed with a heat shield wall 35 that separates the first circuit board 12 and the second circuit board 13. The heat shield wall 35 blocks heat generated from the electronic component 24 </ b> A mounted on the first circuit board 12 when energized, and suppresses heat from being transmitted to the second circuit board 13. .

(Heat dissipation structure)
As shown in FIG. 5, the plate surface of the first circuit board 12 is accommodated in the case 11 in a posture along the wall surface of the heat radiating wall 36 located on the lower side of the case 11 in FIG. 5. The heat radiating wall 36 receives heat generated in the first circuit board 12 when energized and dissipates it to the outside of the case 11.

  In the case 11, a wall (a wall positioned on the upper side in FIG. 5) facing the heat radiating wall 36 is a facing wall 37. The holding member 27 is disposed in the case 11 so as to be positioned on the opposite wall 37 side (the upper side in FIG. 5) with respect to the first circuit board 12.

(Abutting part 38)
As shown in FIG. 5, the holding member 27 has a plurality of abutting portions 38 that abut against the opposing wall 37 from the inside of the case 11 (downward in FIG. 5). As shown in FIG. 15, the abutting portion 38 is a wall surface (upper surface in FIG. 15) of the holding member 27 that faces the facing wall 37, and is provided in a region different from the housing portion 31.

(Pressing part 39)
In addition, the holding member 27 has a plurality of pressing portions 39 that come into contact with the first circuit board 12 from the inside of the case 11 (upper side in FIG. 5) and press it toward the heat radiating wall 36. By being pressed by the pressing portion 39, the first circuit board 12 and the heat radiating wall 36 are brought into close contact with each other.

  As shown in FIGS. 11 and 12, the pressing portion 39 is provided so as to protrude from the region on the first circuit board 12 side of the holding member 27 toward the first circuit board 12 side (upward in FIG. 11). Yes.

  As shown in FIG. 11, the pressing portion 39 includes first pressing portions 39 </ b> A that are discretely formed at the four corners of the holding member 27. The first pressing portion 39A has a prismatic shape. The first pressing portion 39A presses the four corners of the first circuit board 12 in a state where the first circuit board 12 is attached to the holding member 27. The positioning protrusion 30 described above is provided at the tip of the first pressing portion 39A.

  Further, the pressing portion 39 includes a second pressing portion 39B formed in an elongated rib shape located at a bent portion (a side edge on the left front side in FIG. 11) between the first circuit board 12 and the connector connecting portion 25. The second pressing portion 39B presses a portion of the first circuit board 12 corresponding to the bent portion with the connector connecting portion 25 in a state where the first circuit board 12 is attached to the holding member 27. Yes.

  Further, the pressing portion 39 includes a third pressing portion 39C provided at a substantially central portion in the longitudinal direction of the holding member 27 (the direction indicated by the arrow A in FIG. 11). The third pressing portion 39C has a prismatic shape. The third pressing portions 39C are provided discretely at positions near both ends and in the substantially central portion in the direction orthogonal to the longitudinal direction of the holding member 27 (the direction indicated by the arrow B in FIG. 11). The third pressing portion 39 </ b> C presses the substantially central portion in the longitudinal direction of the first circuit board 12 in a state where the first circuit board 12 is attached to the holding member 27.

(Shape of case 11)
As shown in FIG. 23, both the heat radiating wall 36 and the opposing wall 37 are formed in the case 11 in a state before the first circuit board 12, the second circuit board 13, and the holding member 27 are accommodated in the case 11. It is formed in a shape bent inward. When the first circuit board 12, the second circuit board 13, and the holding member 27 are not accommodated in the case 11, the distance between the facing wall 37 and the heat radiating wall 36 is determined by assembling the first circuit board 12 to the holding member 27. In this state, the dimension is set to be smaller than the dimension between the tip of the contact portion 38 (upper edge in FIG. 24) and the outer surface of the first circuit board 12 (lower surface in FIG. 24). Accordingly, when the holding member 27 in a state where the first circuit board 12 and the second circuit board 13 are assembled is accommodated in the case 11, the contact portion 38 is pressed inward of the case 11 by the opposing wall 37. The force is transmitted to the pressing portion 39 so that the first circuit board 12 is pressed toward the heat radiating wall 36.

(Heat dissipation window 40)
As shown in FIGS. 5 and 6, a space is formed between the first circuit board 12 and the holding member 27. Specifically, this space is formed between the first circuit board 12 and the heat shield wall 35 of the holding member 27. In this space, an electronic component 24A mounted on the first circuit board 12 is accommodated.

  As shown in FIGS. 17, 18, and 19, the side wall of the holding member 27 is formed with a heat radiating window 40 that is notched from the edge on the first circuit board 12 side. A space formed between the first circuit board 12 and the holding member 27 and an external space communicate with each other through the heat radiating window 40.

  In a state where the first circuit board 12 and the holding member 27 are accommodated in the case 11, the heat radiating window 40 provided in the holding member 27 is disposed to face the inner wall of the case 11. Thereby, the inner wall of the case 11 is exposed in the space between the first circuit board 12 and the holding member 27.

(Assembly process)
Then, an example of the manufacturing process of the electrical junction box 10 which concerns on this embodiment is demonstrated. In addition, the manufacturing process of the electrical junction box 10 is not limited to the following description. First, as shown in FIGS. 8 and 9, the electronic component 24A is mounted on the surface of the first circuit board 12 by a known method such as soldering. Further, the connector terminal 19 is connected to the connector connecting portion 25 by a known method such as soldering. Thereafter, the connector connecting portion 25 is bent.

  Subsequently, as shown in FIG. 10, one edge of the connection substrate 32 is connected to the edge of the first circuit substrate 12 by a known method such as soldering. Thereafter, the other edge of the connection board 32 is connected to the edge of the second circuit board 13 by a known method such as soldering.

  Subsequently, as shown in FIG. 12, the positioning protrusions 30 of the holding member 27 are inserted into the positioning holes 29 of the first circuit board 12 to perform relative positioning between the first circuit board 12 and the holding member 27. However, the first circuit board 12 is assembled to the holding member 27. Further, the bent connector connecting portion 25 is arranged along the wall surface of the holding member 27.

  Subsequently, the connection board 32 is bent into a predetermined shape, and the second circuit board 13 is housed in the housing portion 31 of the holding member 27 (see FIGS. 14 and 15). Thereafter, the second circuit board 13 is fixed to the holding member 27 with bolts 28.

  Subsequently, as shown in FIGS. 21 and 22, the lid 15 is screwed to the holding member 27 with bolts 28. At this time, one end portion of the connector terminal 19 is arranged in the fitting portion 18 of the lid portion 15.

  Thereafter, a structure in which the first circuit board 12, the second circuit board 13, the holding member 27, and the lid portion 15 are assembled into the case 11 is inserted from the opening portion 14 of the case 11. At this time, the above-described component is inserted in a posture in which the lid portion 15 is located on the rear side in the insertion direction. Then, after the first lock protrusion 16 formed on the case 11 is elastically deformed and rides on the first lock protrusion 16 formed on the lid portion 15, the first lock protrusion 16 is restored and deformed. As a result, the first lock receiving portion 17 is elastically engaged with the first lock protrusion 16, and the lid portion 15 and the case 11 are assembled together.

  Subsequently, although not shown in detail, the mating connector is fitted into the fitting portion 18 of the lid portion 15. Thereafter, the wire cover 20 is assembled to the case 11. Then, after the second lock receiving portion 22 formed on the electric wire cover 20 is elastically deformed and rides on the second lock projecting portion 21 formed on the outer surface of the case 11, the deformation is restored. As a result, the second lock receiving portion 22 is elastically engaged with the second lock protrusion 21, and the electric wire cover 20 is assembled to the case 11. Thus, the electrical junction box 10 is completed.

(Function, effect)
Then, the effect | action and effect of this embodiment are demonstrated. According to the present embodiment, the contact portion 38 is in contact with the opposing wall 37 from the inner surface of the case 11. As a result, a force directed from the facing wall 37 toward the inside of the case 11 is applied to the contact portion 38. This force is transmitted to the contact portion 38 via the holding member 27. Since the contact portion 38 is in contact with the first circuit board 12 from the inside of the case 11, the contact portion 38 makes contact with the first circuit board 12 from the inside of the case 11 to the outside. The power to go is added. Since the first circuit board is arranged along the heat radiating wall 36, the first circuit board 12 is pressed against the heat radiating wall 36 by the force applied to the first circuit board 12. As a result, it is possible to suppress the formation of an air layer due to a gap between the first circuit board 12 and the heat radiating wall 36.

  When energized in the above state, heat is generated from the electronic component 24A mounted on the first circuit board 12. This heat is transferred to the first circuit board 12. Heat is also generated from the first circuit board 12. As described above, since the formation of an air layer between the first circuit board 12 and the heat radiating wall 36 is suppressed, the heat generated in the first circuit board 12 when energized is generated by the first circuit board 12. From the heat radiating wall 36 to the outside of the case 11.

  Thus, according to the present embodiment, it is possible to suppress the air layer from intervening in the heat transfer path from the electronic component 24 </ b> A to the heat radiating wall 36. In other words, no air layer is interposed, or the air layer can be reduced. Accordingly, heat transfer from the electronic component 24 </ b> A to the heat radiating wall 36 can be improved, so that heat can be prevented from being trapped in the case 11.

  And according to this embodiment, both the heat radiating wall 36 and the opposing wall 37 are the case 11 in the state before the 1st circuit board 12, the 2nd circuit board 13, and the holding member 27 are accommodated in the case 11. It is formed in a shape bent inward. As a result, when the first circuit board 12, the second circuit board 13, and the holding member 27 are accommodated in the case 11, the holding member 27 and the first circuit board 12 are sandwiched between the heat radiating wall 36 and the opposing wall 37. . As a result, the abutting portion 38 of the holding member 27 receives pressure from the opposing wall 37, and the first circuit board 12 is pressed against the heat radiating wall 36 by the pressing portion 39 receiving this pressure. Thereby, compared with the case where the heat radiating wall 36 and the opposing wall 37 are not bent inward of the case 11, the first circuit board 12 can be securely adhered to the heat radiating wall 36. Thereby, it can further suppress that heat is trapped in the case 11.

  Further, when heat is generated in the first circuit board 12 during energization and the temperature of the first circuit board 12 rises, the first circuit board 12 extends in a direction parallel to the plate surface. However, since the first circuit board 12 is accommodated in the case 11, the edge of the first circuit board 12 extending in the direction parallel to the plate surface abuts on the inner wall of the case 11, and the first circuit board 12 Of these, there is a concern that the vicinity of the center in the longitudinal direction bends away from the heat radiating wall 36.

  According to the present embodiment, the first circuit board 12 has a rectangular shape, and the third pressing part 39 </ b> C of the pressing parts 39 is provided so as to press the substantially central part in the longitudinal direction of the first circuit board 12. It has been. Accordingly, the third pressing portion 39C is provided so as to press the substantially central portion in the longitudinal direction of the first circuit board 12 where a gap is more likely to be generated. Can be further suppressed. Thereby, it can further suppress that heat is trapped in the case 11.

  Further, in order to ensure that the first circuit board 12 is in close contact with the heat radiating wall 36, it is conceivable to increase the contact area where the pressing portion 39 and the first circuit board 12 come into contact. On the other hand, an electronic component 24 </ b> A is mounted on the first circuit board 12. If the contact area between the pressing portion 39 and the first circuit board 12 is excessively wide, there is a concern that the region where the electronic component 24A can be mounted becomes narrow.

  Therefore, in the present embodiment, by disposing the pressing portions 39 discretely, the first circuit board 12 can be brought into close contact with the heat radiating wall 36 and a mounting area for the electronic component 24A can be secured.

  In addition, according to the present embodiment, a space is formed between the first circuit board 12 and the holding member 27, and the first circuit board 12 and the portion of the holding member 27 facing the case 11 are A heat dissipation window 40 that exposes the inner wall of the case 11 is provided in an open space in the space between the holding member 27. Thereby, the heat generated in the first circuit board 12 or the electronic component 24A when energized is dissipated in the space surrounded by the holding member 27 and the first circuit board 12, and then exposed in the heat dissipation window 40. Is transmitted to the inner wall. Thereafter, heat is dissipated from the case 11 to the outside. Thereby, it can further suppress that heat is trapped in the case 11.

  Further, according to the present embodiment, the holding member 27 is provided with the heat shield wall 35 that shields heat between the first circuit board 12 and the second circuit board 13. Thereby, it is possible to suppress the heat generated in the first circuit board 12 during energization from being transmitted to the second circuit board 13. Similarly, the heat generated in the second circuit board 13 can be suppressed from being transmitted to the first circuit board 12. As a result, it is possible to prevent the electronic components 24A and 24B mounted on one of the first circuit board 12 and the second circuit board 13 from malfunctioning due to heat generated on the other circuit board. In this embodiment, one of the first circuit board 12 and the second circuit board 13 is mounted with a heat generating component that generates heat when energized, and the other is mounted with relatively heat-sensitive electronic components 24A and 24B. It is effective in the case.

  In the present embodiment, the end of the holding member 27 located on the opening 14 side of the case 11 is the connector of the first circuit board 12 when the mating connector is fitted in the fitting portion 18. The force applied to the connector terminal 19 when the mating connector is fitted is transmitted to the holding member 27 via the connector connecting portion 25 in contact with the connecting portion 25. The force transmitted to the holding member 27 is transmitted to the case 11 via the back wall contact portion 34. Thus, according to this embodiment, the case 11 can receive the force applied to the connector terminal 19 when the mating connector is fitted. Thereby, it is suppressed that the connection board 32 or the 1st circuit board 12 deform | transforms with the force added to the connector terminal 19. FIG.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In this embodiment, although the example which applied this invention to the electrical junction box 10 was shown, it is not restricted to this, This invention has the structure by which a circuit board is accommodated in case 11, such as what is called ECU. Applicable to any circuit unit.
(2) As the shape of the pressing portion 39, any shape such as a columnar shape, a plate shape, or a pin shape may be adopted as necessary.
(3) In the present embodiment, the first circuit board 12 is housed in the case 11 in a state in which the first circuit board 12 is assembled to the holding member 27. However, the present invention is not limited to this. The holding member 27 may be accommodated after accommodating the first circuit board 12 after the retaining member 27 is accommodated first.
(4) In the present embodiment, the heat radiation window 40 is opened in the holding member 27, but the heat radiation window 40 can be omitted.
(5) Although the heat shield wall 35 is provided between the first circuit board 12 and the second circuit board 13 in the present embodiment, the heat shield wall 35 may be omitted. Further, the second circuit board 13 may be omitted, and in this case, the heat shield wall 35 may be omitted.
(6) In the present embodiment, in the state before the first circuit board 12, the second circuit board 13, and the holding member 27 are accommodated in the case 11, both the heat radiation wall 36 and the opposing wall 37 are the case. However, the present invention is not limited to this, and only the heat radiating wall 36 may be formed to be bent, or only the opposing wall 37 is bent. It may be formed in an irregular shape.
Moreover, it is good also as a structure by which the thermal radiation wall 36 and the opposing wall 37 are mutually formed in parallel.
(7) The 1st circuit board 12 or the 2nd circuit board 13 is good also as a structure formed by sticking FPC (flexible printed circuit board) to one side of a bus bar. Moreover, it is good also as a structure formed by sticking FPC on the single side | surface or both surfaces of a copper thin film. Further, for example, a flexible substrate such as a rigid flexible substrate is bent twice at right angles to form a shape corresponding to the first circuit board 12, the connection board 32, and the second circuit board 13. May be. As described above, the first circuit board 12 and the second circuit board 13 may adopt any configuration as necessary.

10 ... Electrical junction box (circuit unit)
DESCRIPTION OF SYMBOLS 11 ... Case 12 ... 1st circuit board 13 ... 2nd circuit board 14 ... Opening part 15 ... Cover part 27 ... Holding member 35 ... Heat insulation wall 36 ... Radiation wall 37 ... Opposite wall 38 ... Contact part 39A ... 1st press Part (pressing part 39)
39B ... 2nd press part (press part 39)
39C ... 3rd press part (press part 39)
40 ... Radiating window

Claims (4)

A circuit unit having a case in which an opening provided on one end face is closed by a lid, and a first circuit board accommodated in the case;
The case has a wall surface parallel to the opening direction of the opening, receives a heat generated in the first circuit board when energized, and dissipates it to the outside of the case, and an opposing wall facing the heat dissipation wall And having
The first circuit board is housed in the case in a posture in which the plate surface of the first circuit board is along the wall surface of the heat radiating wall,
A holding member that holds the first circuit board and is located on the opposite wall side with respect to the first circuit board is accommodated in the case, and the holding member is disposed on the opposite wall within the case. A contact portion that contacts from the side, and a pressing portion that contacts the first circuit board from the inside of the case and presses the first circuit board against the heat radiating wall,
The case contains a second circuit board disposed on the opposite wall side with respect to the holding member, and the holding member is provided between the first circuit board and the second circuit board. A circuit unit that is provided with a heat shield wall that shields heat . Both or one of the heat radiating wall and the opposing wall are formed in a shape bent inward of the case before the first circuit board and the holding member are accommodated in the case. The circuit unit according to claim 1. The circuit according to claim 1, wherein the first circuit board has a rectangular shape, and the pressing portion is provided so as to press a substantially central portion in a longitudinal direction of the first circuit board. unit. A space is formed between the first circuit board and the holding member, and a heat radiating window that exposes the inner wall of the case is opened in the space of the holding member facing the case. The circuit unit according to any one of claims 1 to 3, wherein the circuit unit is provided.

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