JP2006074921A - Electric junction box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric junction box excellent in heat radiation, to solve the problem that, in a state that a substrate and a bus bar are bonded to each other, there is a possibility that the substrate and the bus bar are caused to warp due to a difference in a expansion coefficient arising from a difference in a material between them (for example, synthetic resin or the like and metal), in such a case that a gap formed between the bus bar and a lower case prevents heat from being sufficiently dissipated to the outside. <P>SOLUTION: The electric junction box is formed by placing a circuitry body 10 obtained by mounting elements on a substrate 11 in a housing 29 obtained by combining an upper case 30 and a lower case 20. It is so constructed that heat from the circuitry body 10 is dissipated through the lower case 20. The upper case 30 is provided with a retainer 36 that is protruded toward the lower case 20 and presses the circuitry body 10 against the bottom plate 21 of the lower case 20. A small-diameter stem 37 that is stepwise reduced in diameter is formed at the tip of the retainer 36 so that it is protruded. A through hole 24 for inserting the small-diameter stem 37 is formed in the circuitry body 10 and the lower case 20. The tip of the small-diameter stem 37 protruded on the side of the under surface of the lower case 20 has a coming-off preventing large diameter 24A formed by melting the tip on the side of the undersurface of the lower case 20 with the substrate 11 retained by the retainer 36. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrical junction box.

  Conventionally, as an electrical junction box used to distribute power from a common in-vehicle power source to various electronic units, a circuit structure (for example, a control circuit board (board), a switching element, and a bus bar) is used as an upper case and a lower case. There is what is accommodated in the housing which consists of (refer patent document 1).

  In this type of circuit structure, a circuit pattern is formed on the upper surface of the substrate. On this circuit pattern, a switching element for controlling conduction of power and a control circuit for controlling driving of the switching element. The element is mounted. On the other hand, a bus bar electrically connected to the circuit pattern is bonded to the lower surface of the substrate via an insulating layer, and a lower case is bonded to the lower surface of the bus bar via the insulating layer.

  And a circuit structure is accommodated in a case by fitting an upper case from the upper part of this lower case.

Here, since a large current flows through the power conduction path (such as a bus bar), the amount of heat generated from the switching element becomes relatively large accordingly, while the control circuit element malfunctions when it is affected by heat. Cheap. Therefore, it is desirable that the heat generated from the switching element is released to the outside (outside the case) without being transferred to the control circuit element.
JP 2003-164040 A

  By the way, the heat generated in the switching element is transferred to the lower case via the substrate and the bus bar, and then released to the outside. Here, when these members are not in close contact, that is, when a gap (air layer) is formed between these members, heat is trapped in the gap and heat is not sufficiently released to the outside. . In particular, in a state where the board and the bus bar are bonded, there is a possibility that the board and the bus bar are warped due to a difference in expansion coefficient due to the difference in these materials (for example, synthetic resin and metal). Heat is not easily released to the outside due to a gap formed between the upper case and the lower case.

  This invention is completed based on the above situations, Comprising: It aims at providing the electrical junction box with favorable heat dissipation.

  As a means for achieving the above object, the invention according to claim 1 is characterized in that a circuit structure in which an element is mounted on a substrate is accommodated in a housing in which an upper case and a lower case are combined. An electrical junction box that dissipates heat from a body through the lower case, wherein the upper case protrudes toward the lower case and presses the circuit component against a contact portion with the lower case It is characterized by a configuration in which a portion is provided.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the lower case includes a heat sink.

  The invention of claim 3 is characterized in that, in the invention of claim 1, the lower case is made of a synthetic resin.

  According to a fourth aspect of the present invention, in the circuit structure according to any one of the first to third aspects, the circuit structure is configured such that an element is mounted on a rectangular substrate, and a bus bar stacked on the lower surface of the substrate is the substrate. The circuit on the substrate and the bus bar form a conductive path by being bonded to each other, and the pressing portion is provided so as to press a substantially central portion in the longitudinal direction of the substrate. Have

The invention according to claim 5 is the one according to any one of claims 1 to 4,
A tip of the pressing portion is formed with a small-diameter shaft portion that is reduced in a stepped diameter, while a through-hole that penetrates the small-diameter shaft portion is formed in the circuit component and the lower case, At the tip of the small-diameter shaft portion that protrudes to the lower surface side of the lower case is provided with a large retaining diameter portion that is melted and crushed on the lower surface side of the lower case while the substrate is pressed by the pressing portion. Has features.

  According to a sixth aspect of the present invention, in the apparatus according to any one of the first to fourth aspects, the tip of the pressing portion is reduced in a stepped shape, and a small-diameter shaft portion having a screw hole on the front end surface is projected. In addition, the circuit structure and the lower case are formed with through-holes that pass through the small-diameter shaft portion, and further, the small diameter that protrudes to the lower surface side of the lower case in a state where the substrate is pressed by the pressing portion. It has a feature in that it has a screw screwed into the screw hole of the shaft portion, and a washer made of an elastic material sandwiched between a head portion of the screw and a peripheral edge of the through hole of the lower case.

<Invention of Claim 1>
According to this structure, since the holding | suppressing part presses a circuit structure to a contact site | part with a lower case, a clearance gap (air layer) does not arise easily between a board | substrate and a lower case, and can improve heat dissipation.

<Invention of Claim 2>
According to this configuration, heat can be released from the heat sink.

<Invention of Claim 3>
According to this configuration, heat is radiated to the outside from the lower case made of synthetic resin. Therefore, it is not necessary to provide a heat sink made of another member (metal or the like).

<Invention of Claim 4>
According to this configuration, since the pressing portion is provided so as to press the substantially central portion in the longitudinal direction of the board where a gap is more likely to be generated, a gap is hardly generated between the board and the lower case, and heat dissipation is improved. Can do.

<Invention of Claim 5>
According to this configuration, the separation between the circuit configuration body and the lower case can be restricted.

<Invention of Claim 6>
According to this configuration, the separation between the circuit configuration body and the lower case can be restricted. In addition, since the screw is screwed through the washer made of an elastic material, the washer can relieve the stress generated in the substrate due to the pressing of the pressing portion, and a crack or the like may occur in a joint portion between the circuit and the element on the substrate. Can be prevented.

<Embodiment 1>
A first embodiment of the present invention will be described below with reference to FIGS.
In the electrical junction box of this embodiment, the circuit component 10 is housed in a housing 29 formed by fitting the lower case 20 and the upper case 30 (see FIG. 1), and power is supplied to a vehicle (not shown). It distributes to the road, distributes the current from the power source and supplies it to each part of the vehicle, and dissipates heat generated from the circuit component 10 to the outside through the lower case 20 at this time.

  As shown in FIG. 2, the circuit structure 10 includes a rectangular substrate 11 (circuit substrate) formed by laying a pattern (circuit) on an insulating base, and a bus bar 13 formed by punching a metal plate into a predetermined pattern. And a switching element 12 (for example, a mechanical relay switch or a semiconductor switching element) is mounted on the surface of the substrate 11 side.

  In the present embodiment, the substrate 11 forms a control circuit that mainly controls the driving of the switching element 12, and the bus bar 13 forms a power circuit that supplies a power supply current.

  Here, the board | substrate 11 and the bus-bar 13 are integrated (adhered) via the thin adhesive sheet 19 which has insulation (refer the partial enlarged view of FIG. 3). The substrate 11 and the bus bar 13 are bonded to each other in a step before the switching element 12 is mounted on the substrate 11. Since the switching element 12 is not mounted on the substrate at the time of bonding, the adhesive sheet 19 is pressed against the entire back surface of the substrate 11 and the surface of the bus bar 13 by uniformly pressing the entire surface of the substrate 11 with a press or the like. The substrate 11 and the bus bar 13 are firmly bonded to each other without generating a gap between them by such a whole surface pressing.

  Further, the extending portion of the bus bar 13 extending to the left in FIG. 7 is bent vertically upward along the upright wall 22 at the rear portion of the lower case 20, and is again outward at the tip (upper end) of the upright wall 22. It is bent perpendicularly (to the left in FIG. 7) and bent in a crank shape as a whole. The distal end of the extended portion bent in a crank shape has one connector on the right side and two connectors on the left side of the connector block 28 comprising six connector housings 28A (see FIG. 1) connected to the rear end of the housing 29. The connector terminal portion 13A is formed by being accommodated in the housing 28A.

  Further, the circuit component 10 is provided with a control terminal 14 whose one end projects into the second to fourth connector housings 28A from the right of the connector block 28. As shown in FIG. 8, the control terminal 14 has an L shape, and is press-fitted at a predetermined interval in the width direction into a terminal support base 17 provided at the rear end portion in the housing 29. Then, the other end side of the control terminal 14 is passed through and soldered to a through hole 10C provided in the circuit structure 10 so as to be electrically connected to the control circuit, and the tip thereof is an upper surface 21B (surface) of the lower case 20 ) Is accommodated in a recess 21A. The terminal support 17 is fixed on the substrate 11 by being fastened with screws 18 across the substrate 11 and the bus bar 13.

  Further, as shown in FIG. 5, a power supply side terminal portion 15 connected to a power supply side terminal (not shown) is provided at a substantially central portion of the end of the housing 29 opposite to the connector block 28 side. Is formed so as to protrude upward, and a current from the power supply side is supplied from here to the circuit structure 10 in the housing 29, and this current is distributed and flows to the connector terminal portion 13 </ b> A of the bus bar 13 and the control terminal 14. It is like that.

  The lower case 20 is made of synthetic resin. As shown in FIGS. 2 and 3, the lower case 20 is a flat plate along the outer shape of the substrate 11 and has a rectangular bottom plate 21. The protruding upright wall 22 is integrally provided. In addition, among the standing walls 22 of the bottom plate 21, the left and right standing walls 22 are provided with engaging claw portions 23 protruding in a pair of front and rear. The engaging claw portion 23 is formed with a tapered surface 23A that becomes tapered toward the tip after the outer surface is enlarged in a stepped shape at an almost intermediate height. When the upper case 30 and the lower case 20 are fitted to each other, a taper surface 33A of the upper case 30 (to be described later) is brought into sliding contact with the taper surface 23A so that the engaging claw portion 23 bends inward. , 30 reaches the predetermined fitting position, the engaging claw portion 23 is restored and deformed to engage with the engaging portion 33 of the upper case 30, so that the fitting state of both cases 20, 30 is maintained. It has become.

  As shown in FIGS. 1 and 3, the upper case 30 is a flat top plate 31 that follows the outer shape of the substrate 11, and the upper case 31 extends downward from the peripheral edge of the top plate 31 (on the lower case 20 side). ) And the protruding wall portion 32 are integrally provided. The height of the wall portion 32 is a height at which the tip (lower end) of the wall portion 32 reaches the bottom plate 21 of the lower case 20 when the cases 20 and 30 are fitted together. The front end portion (lower end portion) on the inner surface side is formed into an engaging portion 33 having a tapered surface 33 </ b> A that is tapered toward the front end after the diameter is increased in a stepped shape inward.

  As shown in FIG. 1, the top plate 31 is provided with a plurality of fuse insertion openings 34 arranged on both sides of the power supply side terminal portion 15, and the current from the power supply is obtained by attaching the fuses 35 to the top plate 31. It is distributed to each part via the fuse 35 so that no overcurrent is supplied to each part.

In the present embodiment, as shown in FIGS. 2 and 3, the upper case 30 is formed with a pressing portion 36 that presses the circuit component 10.
The pressing portion 36 is formed so as to protrude downward at each corner portion of the lower surface of the top plate 31 of the upper case 30 and at the front end portion in the substantially central portion of the substrate 11 in the longitudinal direction, and is substantially the same length as the wall portion 32. The height (height) is a cylinder (bar) that is slightly thicker than a through-hole 24 described later.
The pressing portion 36 presses the surface of the substrate 11, thereby eliminating a gap (air layer) between the circuit structure 10 and the lower case 20, and radiating heat generated from the circuit structure 10. It comes to improve the nature.

  In addition, a stepped surface 36A having a stepped diameter reduced from the pressing portion 36 is formed at the tip of the pressing portion 36, and the tip of the stepped portion 36A is slightly longer than the thickness of the circuit component 10 and the lower case 20 overlapped. A small-diameter shaft portion 37 slightly narrower than 24 is formed so as to protrude. The material of the small-diameter shaft portion 37 is the same as that of other portions of the upper case 30, and a synthetic resin that is brought into a molten state by heat, such as a modified PPE resin, is used.

  On the other hand, in the circuit board 10 and the bottom plate 21 of the lower case 20, as shown in FIG. 3, a circular through hole 24 that passes coaxially in the vertical direction (direction perpendicular to the plate surface of the substrate 11) has a rectangular shape. Are formed at positions corresponding to the pressing portions 36 of the upper case 30 on the front end side of each corner portion of the substrate 11 and the substantially central portion of the substrate 11 in the longitudinal direction. When the bus bar 13 is present at the position where the through hole 24 is formed, the through hole 24 is also formed through the bus bar 13, but the bus bar 13 is not present at the position where the through hole 24 is formed. In this case, no through hole is formed in the bus bar 13.

  Further, a diameter-expanded hole portion 24A having a stepped diameter is formed at the back end portion of the through-hole 24 (lower end portion of the lower case 20), and a small-diameter shaft of the pressing portion 36 is formed in the diameter-expanded hole portion 24A. When the melted portion of the portion 37 is filled, the retaining diameter large portion 37A having a size corresponding to the diameter-enlarged hole portion 24A is formed so as to be flush with the lower surface (back surface) of the lower case 20 (FIG. 11 ( B)), the separation between the bus bar 13 (circuit structure 10) and the lower case 20 is regulated.

Next, functions and effects of this embodiment will be described.
First, as shown in FIG. 3, the circuit component 10 is placed inside the upright wall 22 on the lower case 20, and the small diameter shaft portion 37 of the pressing portion 36 is inserted into the through hole 24 of the circuit component 10 and the lower case 20. Then, the upper case 30 is fitted from above the lower case 20. Then, when the upper case 30 is moved downward as it is, the stepped surface 36A of the pressing portion 36 contacts and presses against the surface of the substrate 11 (circuit structure 10), and the lower surface 13B of the bus bar 13 is formed on the bottom plate 21 of the lower case 20. Adheres to the upper surface 21B without any gap (air layer). At this time, the tip of the small diameter shaft portion 37 protrudes from the lower surface of the lower case 20 (FIG. 11A).

  Here, the distal end portion of the small diameter shaft portion 37 is melted by heat to be expanded and deformed. Then, as shown in FIG. 11 (B), the tip of the small-diameter shaft portion 37 is fixed (thermally welded) to the enlarged-diameter hole portion 24A, and the circuit component 10 (the bus bar 13) and the lower case 20 are in close contact with each other. Retained. Thereby, even if it does not use an adhesive agent, the bus-bar 13 (circuit structure 10) and the lower case 20 can be closely_contact | adhered (separation of the circuit structure 10 and the lower case 20 is controlled) without a clearance gap (air layer).

Thereafter, the connector housing 28A is assembled, and the fuse 35 is inserted into the fuse insertion port 34, whereby the assembly of the electrical junction box is completed.
For example, this electrical junction box is placed vertically in the power supply path of the vehicle (in the direction in which the connector terminal portion 13A side is downward), and the power supply side terminal portion 15 is electrically connected to the power source (alternator, battery, etc.) of the vehicle. At the same time, the connector terminal portion 13A and the control terminal 14 are electrically connected to terminals (not shown) of the mating connector connected to each device of the vehicle, whereby the power source current of the vehicle is distributed to each device in the vehicle.

  As described above, according to the present embodiment, since the pressing portion 36 presses the circuit structure 10, no gap (air layer) is generated between the circuit structure 10 and the lower case 20, and heat dissipation is achieved. Can be improved. Even if the circuit structure 10 may be warped due to a change in ambient temperature or the like, since the pressing portion 36 suppresses deformation, a gap (air layer) is hardly generated between the circuit structure 10 and the lower case 20, The heat dissipation can be improved.

  Moreover, since the holding | suppressing part 36 closely_contact | adheres the circuit structure 10 to the lower case 20, it becomes possible to fully transmit heat to the lower case 20, and since heat is radiated outside from the lower case 20 made of synthetic resin, other members (metal or the like) The heat dissipating property is ensured without providing the heat dissipating means.

  Furthermore, since the pressing portion 36 presses the substantially central portion in the longitudinal direction of the substrate 11 where gaps are more likely to occur, a gap is less likely to occur between the circuit component 10 and the lower case 20, and heat dissipation can be improved. .

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIG.
In the above embodiment, the tip of the small diameter shaft portion 37 is melted so that the lower surface 13B of the bus bar 13 and the upper surface 21B of the bottom plate 21 of the lower case 20 are in close contact with each other without a gap (air layer).
In the second embodiment, the small-diameter shaft portion 37 is fastened with a screw 41 to bring the lower surface 13B of the bus bar 13 and the upper surface 21B of the lower case 20 into close contact with each other without a gap (air layer). In addition, about the same structure, the same code | symbol is attached | subjected and description is abbreviate | omitted.

Specifically, as shown in FIG. 12A, the length of the small-diameter shaft portion 37 is substantially the same as the thickness of the circuit structure 10 and the lower case 20 stacked without any gaps, and the small-diameter shaft portion 37 is formed. A screw hole 42 is provided in the front end surface of. The circuit structure 10 and the lower case 20 are each provided with a through hole 44 that continuously penetrates up and down with a uniform diameter.
Then, the screw 41 is screwed into the screw hole 42 via the annular washer 43 made of synthetic resin (made of elastic material) larger than the through hole 44, so that the washer 43 is formed as shown in FIG. The circuit component 10 and the lower case 20 are fixed while being sandwiched between the head 41 </ b> A of the screw 41 and the peripheral edge 44 </ b> A at the lower end of the through hole 44.

  In this way, the separation between the circuit structure 10 and the lower case 20 can be regulated. Further, since the screw 41 is screwed through the washer 43 made of synthetic resin (made of elastic material), the washer 43 can relieve the stress generated on the substrate 11 due to the pressing of the pressing portion 36. It is possible to prevent a crack or the like from occurring at the joint portion (soldered portion) between the circuit and the element.

<Embodiment 3>
In the above embodiment, the entire lower case 20 is molded from a synthetic resin. However, in the third embodiment, the bottom plate 21 of the lower case 20 is made of a metal (for example, aluminum alloy) heat radiating plate (for example, an aluminum alloy). The heat is dissipated from the heat radiating plate.
In this way, heat can be sufficiently dissipated from the lower case 20.

<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, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

  (1) In the above embodiment, the bus bar 13 of the circuit component 10 is stacked on the bottom plate 21 of the lower case 20 without using an adhesive, but the lower surface 13B of the bus bar 13 and the bottom plate of the lower case 20 are formed by an insulating adhesive sheet. It is good also as a structure which adhere | attaches 21 upper surface 21B.

  (2) In the above embodiment, the pressing portion 36 is provided on the front end portion side of each corner and the substantially central portion in the longitudinal direction of the substrate 11 in the lower surface of the upper case 30, but the present invention is not limited to these places. You may provide in a location. Moreover, although the number of the holding | suppressing parts 36 was five of the above-mentioned places, it may be less than this or more.

  (3) In the above embodiment, the distal end portion of the small diameter shaft portion 37 is melted and fixed in a state where the small diameter shaft portion 37 at the distal end of the pressing portion 36 is passed through the through hole 24 of the circuit configuration body 10. 10 and the lower case 20 are brought into close contact with each other so that the pressing portion 36 presses the substrate 11 (circuit structure 10). However, the small-diameter shaft portion 37 and the through hole 24 are not provided. It is good also as a structure which presses the board | substrate 11 (circuit structure 10) with the whole flat front end surface (lower end surface), and improves the heat dissipation outside the lower case 20. FIG.

  (4) In the above-described embodiment, the material of the small diameter shaft portion 37 is the modified PPE resin. However, the material is not limited to this, and other materials may be used. In this case, preferably, the material of the small-diameter shaft portion 37 is made of a material having a melting temperature lower than that of the lower case 20, so that the deformation of the lower case 20 at the time of heat welding can be prevented.

The top view of the electric junction box of a 1st embodiment of the present invention. Cross section of electrical junction box Sectional drawing which shows the state which fits an upper case to a lower case 2 is a schematic cross-sectional view of the AA plane in FIG. Front view of electrical junction box Rear view BB cross section Cross section of CC plane Cross section of DD Side view (A) Enlarged cross-sectional view of the holding part and circuit structure when the upper case is fitted to the lower case (B) Enlarged cross-sectional view showing a state where the small-diameter shaft part is thermally welded (A) Enlarged sectional view before the electrical junction box of the second embodiment of the present invention is screwed (B) Enlarged sectional view showing a state where the small diameter shaft portion is screwed

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Circuit structure 11 ... Board | substrate 12 ... Switching element 13 ... Bus bar 20 ... Lower case 21 ... Bottom plate 24 ... Through-hole 24A ... Expanded-hole part 29 ... Housing 30 ... Upper case 36 ... Holding part 37 ... Small diameter shaft part 37A ... Omission Large stop diameter 41 ... Screw 42 ... Screw hole 43 ... Washer

Claims (6)

An electrical junction box in which a circuit structure in which elements are mounted on a substrate is housed in a housing in which an upper case and a lower case are combined, and heat from the circuit structure is dissipated through the lower case. Because
The electrical connection box, wherein the upper case is provided with a pressing portion that protrudes toward the lower case and presses the circuit component against a contact portion with the lower case. The electrical connection box according to claim 1, wherein the lower case includes a heat sink. The electrical connection box according to claim 1, wherein the lower case is made of a synthetic resin. In the circuit structure, an element is mounted on a rectangular substrate, and a bus bar superimposed on the lower surface of the substrate is bonded to the substrate to form a conductive path between the circuit on the substrate and the bus bar. There,
The electrical junction box according to claim 1, wherein the pressing portion is provided so as to press a substantially central portion in a longitudinal direction of the substrate. A tip of the pressing portion is formed with a small-diameter shaft portion that is reduced in a stepped diameter, while a through-hole that penetrates the small-diameter shaft portion is formed in the circuit component and the lower case, The tip of the small-diameter shaft portion that protrudes to the lower surface side of the lower case is provided with a large retaining diameter portion that is melted and crushed on the lower surface side of the lower case while the substrate is pressed by the pressing portion. The electrical junction box according to any one of claims 1 to 4, wherein the electrical junction box is characterized. The tip of the pressing portion is reduced in a stepped shape, and a small-diameter shaft portion having a screw hole on the tip surface is formed to protrude, and a through-hole through which the small-diameter shaft portion penetrates is formed in the circuit component and the lower case. And a screw that is screwed into the screw hole of the small-diameter shaft portion that protrudes to the lower surface side of the lower case in a state where the substrate is pressed by the pressing portion, and the head of the screw and the lower case The electric junction box according to claim 1, further comprising a washer made of an elastic material sandwiched between a peripheral edge of the through hole.

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