JP2003087934A - Electric junction box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To let out heat produced in the internal circuit of an electric junction box and improve the operating environment for the circuit. SOLUTION: A circuit plate 13 for current distribution through which a large or medium current is passed and a printed board 14 as a circuit for control through which a small current is passed are laminated with an insulating plate 16 in-between to constitute the internal circuit of the electric junction box 10. The insulating plate 16 comprises a heat sink 17 provided with a first insulating layer 18 on the surface 17a thereof on one side and a second insulating layer 19 on the surface 17b thereof on the other side. The first insulating layer 18 and the second insulating layer 19 are so set that the first insulating layer is higher in heat transfer coefficient than the second insulating layer. When the insulating plate 16 is installed, the first insulating layer 18 is positioned on the side of the circuit plate 13 for current distribution, and the second insulating layer 19 is positioned on the side of the printed board 14. Thus, heat produced in the circuit board 13 for current distribution is transferred to the heat sink 17 through the first insulating layer 18, and the heat is then let out of the case of the electric junction box through the heat sink 17.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrical junction box,
Specifically, it is intended to improve the heat dissipation performance against heat generated inside the electric junction box.

[0002]

2. Description of the Related Art An electric connection box mounted on an automobile receives only an internal circuit corresponding to a current distribution function or the like, under the influence of an increase in the number of vehicle-mounted electric components and wire harnesses and progress of electronic control, A form in which an electronic unit of a separate control unit controls the internal circuit is widely used. However, in order to meet the recent increasing demand for miniaturization of electric junction boxes, a circuit for large current or medium current (current value in amperes) having a current distribution function and a small current (several tens of minutes). The one that houses the control circuit in which the current value in milliamperes) flows in the same electrical junction box is beginning to be used. This kind of electrical junction box has been devised in various ways so that the heat generated by the circuit such as a large current is not transferred to the control circuit.

FIG. 6 shows an electric junction box 1 disclosed in Japanese Patent Application Laid-Open No. 2000-83310 in consideration of prevention of heat transfer, which is formed by an upper case 2 and a lower cover 3 which covers the inside. In the space, the base substrate 4 through which a large current or the like for mounting electric components such as the relay R flows, and the electric element 5 for control.
A control board 6 for mounting the above components is housed. The control board 6 on which the electric element 5 having a low heat resistant temperature is mounted is the base board 4
It is fixed in a substantially vertical direction with respect to the inside of the case 2, and a partition wall 2a is provided inside the case 2 to partition the control board 6 from the electric components such as the relay R.

In the electric junction box 1, since the base board 4 and the control board 6 are placed in the above-described positional relationship, heat generated by the base board 4 is difficult to be transferred to the control board 6.
Further, by projecting the partition wall 2, the heat generated by the relay R and the like is prevented from being transmitted, and the reliable operation of the electric element 5 such as the microcomputer is ensured.

[0005]

However, even in the electrical junction box 1 of FIG. 6, if the electrical junction box 1 is used for a long period of time, the heat generated by the relay R or the like causes the bulkhead 2 to be entirely warmed up.
When is heated, heat is also transferred to the control board 6. When the heat is transferred in this way, the operation of the electric element 5 and the like may become unstable, and there is a problem that the reliability of the electric junction box 1 cannot be maintained.

Further, since the base board 4 and the control board 6 are arranged in a positional relationship orthogonal to each other, a wasteful space is inevitably produced, and the height dimension of the electric junction box 1 is controlled by the control board 6.
Since it cannot be made smaller than the length dimension of one side, there is a certain limit to miniaturization of the electric junction box 1, and there is a problem that it is physically impossible to make it smaller than the above dimension. Further, since the partition wall 2 is provided so as to project inside the case 5, a size for providing the partition wall 2 is also required, which is a factor that hinders downsizing of the electrical junction box 1.

The present invention has been made in view of the above problems, and an object thereof is to improve the heat dissipation of the internal circuit without hindering the downsizing of the electrical junction box.

[0008]

In order to solve the above-mentioned problems, the present invention has a current distribution circuit board through which a large current or a medium current flows and a control circuit board through which a small current flows with an insulating plate interposed. In an electric junction box that is housed inside a space formed by an upper case and a lower case in a state of being stacked vertically, the insulating plate is a heat dissipation plate having a first insulating layer on one surface and a second insulating layer on the other surface. And the first insulating layer has a higher heat transfer coefficient than the second insulating layer, the first insulating layer is on the side of the current distribution circuit board, and the second insulating layer is on the control circuit board. The insulating plate is disposed on the side, the heat generated in the current distribution circuit board is transferred from the first insulating layer to the heat dissipation plate, and the transferred heat is released from the heat dissipation plate. We provide an electrical junction box characterized by.

As described above, according to the present invention, the heat is radiated by using the insulating plate which is interposed between the circuit boards and electrically insulates the upper and lower circuit boards from each other. This is different from the idea of only isolating the circuit board for use from heat, and the heat generated is radiated to fundamentally eliminate the heat transmitted to the circuit board for control. By interposing the insulating plate between the current distribution circuit board and the control circuit board, it abuts on one surface of the current distribution circuit board that generates heat over a substantially entire area, and mounts electrical parts to generate a large current. Alternatively, the heat generated in the current distribution circuit board through which the medium current flows can be reliably transferred to the insulating board.

Particularly, since the first insulating layer located on the side of the current distribution circuit board of the insulating plate has a higher thermal conductivity than the second insulation layer on the other surface, it is generated in the current distribution circuit board. The generated heat can be smoothly transferred to the first insulating layer, and the transferred heat can be further transferred to the heat dissipation plate and released from the heat dissipation plate. In addition, since the second insulating layer has a low thermal conductivity, the heat transferred to the heat dissipation plate does not move to the second insulating layer, and is easily affected by the heat with which the second insulating layer is in contact. The heat transfer to the control circuit board is cut off to ensure stable circuit operation by heat insulation. Therefore, basically, the first insulating layer is formed of a material having excellent heat transfer characteristics, and the second insulating layer is formed of a material having poor heat transfer characteristics.

Further, in the electric junction box of the present invention, since the internal circuit is formed by the laminated structure of the circuit boards, the height of the electric junction box can be kept lower than that of the conventional electric junction box 1. Since it is not necessary to project a partition wall or the like inside, it is only necessary to configure a minimum internal space, and it is possible to meet the demand for miniaturization.

The heat dissipation plate of the insulating plate is made of a metal plate material,
It is preferable that the first insulating layer and the second insulating layer are formed by resin coating both surfaces of the metal plate material. As described above, when the heat dissipation plate is formed of the metal plate material, the metal material generally has excellent thermal conductivity, so that the heat transferred from the first insulating layer can be efficiently released.
Metals applicable to the heat dissipation plate in consideration of the balance between heat dissipation and cost include aluminum, copper, silver, aluminum alloy, copper alloy, and silver alloy. Also, each insulating layer can be easily formed by coating a metal plate material, which is a heat dissipation plate, with a resin.

In the current distribution circuit board, an electric component is mounted on one surface and the insulating plate is arranged on the other surface. The insulating plate is provided at a portion corresponding to a mounting portion of the electric component. It is preferable to provide an opening in the first insulating layer. When the opening is provided in the first insulating layer in this way, the lead terminals of the electrical component protruding from the back surface of the mounting surface of the current distribution circuit board can be located inside the opening, and the first insulating layer can be stabilized. Then, it can come into contact with the circuit board for current distribution. Further, in the opening portion, the heat generated by the electric component can be surely transmitted to the heat dissipation plate and released by efficient air transmission. In addition, the second insulating layer is not provided with an opening, and the heat sink and the control circuit board are thermally insulated.

The insulating plate extends from the heat radiating plate to form a heat radiating portion without a first insulating layer and a second insulating layer on each surface, and the heat radiating portion is formed by the upper case and the lower case. The heat protruding from the inner space to the outside and generated in the circuit board for current distribution is radiated to the outside from the heat dissipation portion. By forming the heat dissipation part as described above and projecting the formed heat dissipation part to the outside of the case, the heat transmitted to the heat dissipation plate can be released from the heat dissipation part to the outside of the case, preventing heat from staying inside the electrical junction box. As a result, an internal atmosphere suitable for operating conditions of electronic parts such as a microcomputer can be secured. The heat radiating portion may be provided integrally with the heat radiating plate or may be provided separately. Further, the heat radiating portion may be formed in such a shape that the surface area is as large as possible to enhance the heat radiating property. Good.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An electrical junction box according to an embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show an electric connection box 10 according to an embodiment of the present invention, which is a large-sized device in which electric components such as a relay R and a fuse F are mounted as an internal circuit in a space formed by an upper case 11 and a lower case 12. A current distribution circuit board 13 through which a current and a medium current flow, and a printed circuit board 14 as a control circuit board through which a small current flows are housed in a vertically stacked state with an insulating plate 16 interposed.

The current distribution circuit board 13 is a bus bar 15 formed by punching into a desired circuit shape and mounted and fixed on an insulating substrate 13a. One surface 13b, which is a mounting surface, includes a relay R, a fuse F, and the like. The electric parts are directly mounted on the bus bar 15, and a large number of plug-in type relays, fuses, and tabs 15a for connecting connectors of external circuits, which are attached from the outside, are also projected from the one surface 13b. In addition, various electrical components to be mounted are provided with lead terminals for conductive connection, and by mounting the electrical components from one surface 13b, the lead terminals are projected on the other surface 13c.

Further, the circuit formed by the bus bar 15 has a function of distributing a current, and when the current flows through the circuit, the relay R or the like operates to generate a large amount of heat. In addition, in the vicinity of one side 13d of the current distribution circuit board 13, a large number of connecting portions 13e with the printed board 14 are arranged in parallel.

On the other hand, as shown in FIG. 3, various control circuits are formed on the printed circuit board 14, and a large number of electronic components 20, such as FETs and microcomputers, which are easily affected by heat, are mounted on the one surface 14a. There is. It should be noted that, in the vicinity of one side 14b of the printed circuit board 14, a connection portion 14 with the current distribution circuit board 13 is formed.
c is formed, and one end 21a of the jumper wire 21 is joined to the connecting portion 14c by soldering or the like, and the other end 21b is soldered to the connecting portion 13e of the current distribution circuit board 13 or the like. And the required circuit of the current distribution circuit board 13 and the printed circuit board 1 through the jumper wire 21.
4 required circuits are connected to form an internal circuit.

After connecting the jumper wires 19 in this way, the printed circuit board 14 is folded back to the other surface 13c side which is the lower surface of the current distribution circuit board 13 in the direction of the white arrow in the drawing,
An insulating plate 16 is interposed between the current distribution circuit board 13 and the printed circuit board 14 so as to surely insulate the circuits of the current distribution circuit board 13 and the printed circuit board 14 from inadvertent conduction.

The insulating plate 16 is formed by coating the upper surface 17a of the heat radiating plate 17 from one side 17c to a region equivalent to the area of the circuit board 13 for current distribution with a resin to form a first insulating layer 18. Printed circuit board 1 from one side 17c of 17b
The second insulating layer 19 is formed by resin-coating a region equivalent to the area of No. 4.

The heat dissipation plate 17 of the insulating plate 16 is formed of an aluminum plate having a high heat transfer coefficient as a metal plate material, and the width dimension W thereof is substantially equal to the width dimensions of the current distribution circuit board 13 and the printed circuit board 14. It is set to, but one side 17
The dimension from c is set so as to extend beyond the longitudinal dimensions of the current distribution circuit board 13 and the printed circuit board 14, and the extended portion is used as the heat dissipation portion 17d. This heat dissipation part 17d
When the insulating plate 16 is housed in the space inside the upper case 11 and the lower case 12, it projects outside the case.

On the other hand, the first insulating layer 18 formed on the upper surface 17a is made of an insulating resin, and the resin of the first insulating layer 18 has a heat transfer coefficient higher than that of the resin forming the second insulating layer 19. It is expensive. That is, the first insulating layer 18 is made of a resin that can transfer heat very easily. Further, on the first insulating layer 18, one side 13d of the current distribution circuit board 13 and one side 17c of the heat radiating plate 17 and the relay R of the one surface 13b of the current distribution circuit board 13 in a state of being laminated with the widths aligned. An opening 18a is provided at a location corresponding to a mounting location of an electric component such as, and the upper surface 17a of the heat dissipation plate 17 is exposed in the opening 18a. In the present embodiment, since the electrical components such as the relay R are mounted on the current distribution circuit board 13 in three rows, the openings 18a are also formed in three rows.

On the other hand, as shown in FIG. 4, the second insulating layer 19 on the lower surface 17b of the heat dissipation plate 17 is also formed to have a size substantially equal to the outer shape of the printed board 14, and the second insulating layer 19 is formed. The insulating resin has a characteristic that the heat transfer coefficient is very low, and as a result, the second insulating layer 19 functions as a heat insulating layer. The second insulating layer 19 does not have the opening 18a like the first insulating layer 18, and covers the entire area where it abuts the printed circuit board 14 when laminated.

The upper case 11 is resin-molded so as to have an internal space with vertical and horizontal dimensions slightly larger than the outer shapes of the current distribution circuit board 13 and the printed circuit board 14, and the upper surface 11a is of a plug-in type. A relay mounting portion 11b, various fuse accommodating portions 11c, and a connector accommodating portion 11d for connecting to an external circuit are provided. Further, a notch 11f for projecting the heat dissipation portion 17d of the insulating plate 16 is formed on one end side 11e, and a rib 11e for holding an internal circuit is also provided in the internal space.

On the other hand, the lower case 12 is also the upper case 1.
1 is a resin molded product having vertical and horizontal dimensions approximately equal to 1 and having a space inside, a notch 12b for projecting a heat dissipation portion 17d is formed on one end side 12a, and a rib for holding an internal circuit is formed in the internal space. 12c is provided. The upper case 11 and the lower case 12 are lock-coupled to each other. In this coupled state, the current distribution circuit boards 13 and the like that form the internal circuit are housed in a stacked state, so that the conventional electrical junction box 1 of FIG. The height is low and the size is small.

Assembling of the electric junction box 10 is carried out by the current distribution circuit board 1 connected by jumper wires 21 as shown in FIGS.
Insulating plate 16 is interposed between 3 and printed circuit board 14,
The insulating plate 16 is placed on the printed board 14 with the second insulating layer 19 facing downward, and the first insulating layer 18 of the insulating plate 16 is placed.
The current distribution circuit board 13 is placed and laminated on the above. At this time, the other side 17c of the insulating plate 16 is one side 14b of the printed board 14 and one side 13 of the current distribution circuit board 13.
The heat radiating portion 17d is in a protruding state in accordance with d.

These current distribution circuit board 13 and insulating board 1
6. The printed circuit board 14 is housed inside the lower case 12, and the upper case 11 is covered from above and fitted to the lower case 12. At this time, the protruding heat dissipation portion 17
The assembly of the electric junction box 10 is completed by projecting d from the notches 11f and 12b of the upper case 11 and the lower case 12 to the outside.

In the assembled electrical junction box 10, after the required plug-in type relays, fuses, and external circuit connectors have been attached to the relay mounting portion 11b, fuse accommodating portion 11c, and connector accommodating portion 11d of the upper case 11. The electric junction box 10 itself is fixed to a required place in the engine room of the automobile. Since the electric junction box 10 is downsized, the degree of freedom in the layout of attachment to the vehicle body is also improved.

In the electric connection box 10 mounted on the vehicle body as described above, when the internal circuit is energized, the relay R, which is an electric component of the current distribution circuit board 13, is appropriately operated,
Although heat is generated from the relay R and the like, the generated heat is transferred to the heat radiating plate 17 by the first insulating layer 18 in contact with the current distribution circuit board 13 and the air inside the opening 18a. At this time, the first insulating layer 18 has a high heat transfer coefficient, and the air is also excellent in heat transfer, so that the generated heat smoothly moves to the heat dissipation plate 17.

The heat transferred to the heat radiating plate 17 is aluminum, which is also excellent in heat transfer coefficient, so that the heat radiating from the high temperature inside part to the outside air is low based on the principle of heat balance. It moves to the portion 17d and is emitted outward from the heat radiating portion 17d. On the other hand, since the heat transferred to the heat dissipation plate 17 is insulated from the printed board 14 by the second insulating layer 19, the heat is not transferred, and the operation reliability of the microcomputer mounted on the printed board 14 is improved. Is maintained.

Even if a current flows through the internal circuit for a long time to activate the relay R, the heat is continuously released,
The internal temperature of the electric junction box 10 does not rise more than necessary, and the operation of the microcomputer or the like is not disturbed.

The electrical junction box 10 of the present invention is not limited to the above-described embodiment, and for example, like the electrical junction box 10 'of the modified example of FIG. The portion 17e ′ and the lower heat radiation portion 17f ′ may be attached by welding or the like to increase the surface area and further improve the heat radiation performance. In addition to aluminum, silver, copper, aluminum alloys, copper alloys, silver alloys, etc. can be applied to the material of the heat dissipation plate itself. The heat radiating part may be attached to a heat radiating plate provided with the first insulating layer and the second insulating layer.

[0033]

As is apparent from the above description, when the electric junction box of the present invention is used, heat is radiated to the outside of the case, so that even if it is driven for a long time, no heat is trapped inside.
In addition, since the printed circuit board is insulated by an insulating layer with low heat transfer, a stable operating environment can be secured even for electronic components that are weak to heat, and the reliability of the electrical junction box itself can be maintained. Further, according to the present invention, since the internal circuit has a structure in which various circuit boards are laminated, the size in the height direction can be made smaller in comparison with the conventional one, and the degree of freedom of the mounting position on the vehicle body can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an electrical junction box according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the electrical junction box of the embodiment.

FIG. 3 is a perspective view showing a state in which a current distribution circuit board and a printed board are connected by jumpers.

FIG. 4 is a perspective view from the second insulating layer side of the insulating plate.

FIG. 5 is a cross-sectional view of a modified electrical junction box.

FIG. 6 is a cross-sectional view of a conventional electrical junction box.

[Explanation of symbols]

10 electrical junction box 11 upper case 12 lower case 13 Current distribution circuit board 14 Printed circuit board 15 bus bars 16 Insulation plate 17 Heat sink 18 First insulating layer 19 Second insulating layer 21 jumper

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsuyoshi Hosokawa             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd. (72) Inventor Takao Nozaki             1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi             Auto Network Technical Laboratory Co., Ltd. F-term (reference) 5E322 AA03 AA11 AB06 AB08                 5E348 AA02 AA08 AA31 CC08 CC09                       EE38 EE39                 5G361 BA01 BB02 BC01 BC02

Claims (4)

[Claims] 1. A space formed by an upper case and a lower case in which a current distribution circuit board through which a large current or a medium current flows and a control circuit board through which a small current flows are stacked one above the other with an insulating plate interposed therebetween. In the electrical connection box to be housed inside, the insulating plate is a heat dissipation plate having a first insulating layer on one surface and a second insulating layer on the other surface, and the first insulating layer is the second insulating layer. The heat transfer coefficient is set higher, the first insulating layer is arranged on the side of the circuit board for current distribution, and the second insulating layer is arranged on the side of the circuit board for control, and the insulating plate is arranged to form a circuit for current distribution. An electrical junction box, characterized in that heat generated in the plate is transferred from the first insulating layer to the heat dissipation plate, and the transferred heat is released from the heat dissipation plate. 2. The electrical insulation according to claim 1, wherein the heat dissipation plate of the insulating plate is made of a metal plate material, and the first insulating layer and the second insulating layer are formed by resin coating both surfaces of the metal plate material. Connection box. 3. The circuit board for current distribution has an electric component mounted on one surface and the insulating plate disposed on the other surface, and the insulating plate corresponds to a mounting location of the electric component. The electrical junction box according to claim 1 or 2, wherein an opening is provided in the first insulating layer at the location. 4. The insulating plate extends from the heat radiating plate to form a heat radiating part without a first insulating layer and a second insulating layer on each surface, and the heat radiating part is formed by the upper case and the lower case. 4. The electrical junction box according to claim 1, wherein the electrical connection box projects outward from the internal space and discharges the heat generated in the current distribution circuit board outward from the heat dissipation portion.