JP4234245B2 - Electrical junction box - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrical junction box mounted on, for example, an automobile.
[0002]
[Related background]
In recent years, the need for comfort has increased in automobiles, for example, various electrical components such as audio, navigation systems, televisions, electric antennas, air conditioners, rear window heaters, seat heaters, power seats, suspension hardness control, etc. Has been. And the number and kind of such electrical components mounted on the automobile tend to increase.
[0003]
Such electrical components are supplied with power from a battery power source via an electrical junction box. In this electrical junction box, in conjunction with a fuse that prevents a large current from flowing when the wire harness and body are short-circuited or when a load such as a motor breaks down, or an operation switch for electrical components, etc. Electrical components such as relays that control power supply to electrical components are mounted.
[0004]
As an electrical junction box, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-28818, a circuit portion is known in which a bus bar is disposed between insulating plates made of a resin such as plastic. This bus bar is formed by punching or bending a copper, copper alloy, or brass plate material into a desired circuit pattern, and the plurality of bus bars processed into the desired circuit pattern include the circuit pattern and the bus bar. It is placed between compatible plastic insulation plates to maintain insulation. And a fuse, a relay, etc. are attached to the terminal piece of the bus bar extended from the predetermined position of the said insulating board via a connector.
[0005]
In an electrical junction box using a bus bar, a plurality of bus bars are stacked in order to cope with an increase in circuits accompanying an increase in electrical components mounted on an automobile.
As described above, when a plurality of bus bars are stacked, a mold for punching and bending the bus bar and a mold for forming the insulating plate are required for each layer, which increases the manufacturing cost of the mold. In addition, since the number of components increases as the entire electrical junction box, it is difficult to reduce the size of the electrical junction box. Even if it is desired to change the specification, it takes a long time to change the design of the mold of the bus bar or the plastic insulating plate, so in reality, it is necessary to give up the change of the specification.
[0006]
In view of this, an electronic junction box in which the bus bar circuit is replaced by a printed circuit board mainly made of glass epoxy resin, which is generally used in an electronic unit, has been proposed in, for example, Japanese Patent Application Laid-Open No. 9-180831. In manufacturing such a printed circuit board, a mold is not required and the circuit pattern can be changed relatively easily.
[0007]
When the circuit of the bus bar is replaced with a printed circuit board, for example, a relatively thick copper of 70 μm or more is formed on the circuit board in order to form a large current circuit or a medium current circuit electrically connected to the battery or the alternator. It is necessary to form a circuit pattern of foil on the circuit board. On the other hand, when an electrical junction box having a printed circuit board having such a circuit pattern is mounted in the engine room of a vehicle, the glass epoxy resin and the circuit pattern constituting the printed circuit board are affected by the heat effect in the engine room. There is a difference in thermal expansion between the copper foil and the copper foil, and as a result, thermal stress is generated in the circuit pattern, and the copper foil may be peeled off from the glass epoxy resin, or a solder crack may occur in the soldered part. .
[0008]
In order to prevent such problems, a core material made of a metal plate is sandwiched between glass epoxy resins, the thermal expansion of the printed circuit board itself is suppressed by the core material, and the copper foil is peeled off from the glass epoxy resin. It is also conceivable to take a configuration to prevent.
[0009]
[Problems to be solved by the invention]
When a printed circuit board is used instead of a conventional bus bar, heat generated in a large current circuit or a medium current circuit in the electrical junction box cannot be radiated through the bus bar as in the conventional case. Further, as described above, in the case of a printed circuit board having a metal plate as a core material, the heat generated by each heat generating electrical component is collected on the core material via a glass epoxy resin which is an insulating layer. Although the temperature is equalized, heat is stored in the core without being radiated from the core to the outside.
[0010]
Furthermore, as shown in FIG. 4, a method of attaching the radiation fins 1f to each of the heat generating electrical components 1 is also conceivable, but the heat of the entire substrate cannot be drawn only by the radiation fins 1f. In addition, since a large number of heat generating electrical components 1 are mounted on the printed circuit board, if the number of heat generating electrical components 1 increases, the number of heat dissipating fins 1f increases accordingly, leading to an increase in the number of components and the number of assembly steps. A problem arises in terms of cost. Also, the electrical junction box itself cannot be reduced in size. Furthermore, the amount of heat dissipated by the heat radiating fins 1f still exists inside the electric junction box and cannot be efficiently transferred to the outside of the electric junction box.
[0011]
Further, as shown in FIG. 5, a heat pipe 2 is attached to the surface of the printed circuit board, that is, a portion made of glass epoxy resin via a bracket 2b or the like, and an electrical component (not shown) in the vicinity thereof is attached. Although it is conceivable to dissipate the heat generated outside the electrical junction box, this configuration can still transfer heat only from the local heat transferred from the electrical component to the nearby glass epoxy resin, resulting in poor heat collection efficiency. It is enough.
[0012]
An object of the present invention is to provide an electrical junction box that can efficiently dissipate heat generated by electrical components mounted on a printed circuit board to the outside of the electrical junction box.
[0013]
[Means for Solving the Problems]
To achieve the above object, an electrical connection box according to the present invention, the core portion and the core portion of the metal circuit board and an insulating portion sandwiching the sandwich in an electric connection box which is accommodated in an enclosure there are, the insulating portion of the circuit board, the core portion exposed by partially removing toward from the circuit board edge on the inside, a crank in accordance with the step between the core portion which has the exposed and the insulating portion The heat absorption part of the heat pipe bent into a shape is directly adhered .
[0014]
The heat generated by the electrical components such as the fuse holder and the relay mounted on the circuit board is collected in the core part of the circuit board to equalize the heat, and the heat is radiated from the exposed core part. In the electrical junction box according to the present invention , the heat absorbing portion of the heat pipe bent into a crank shape is directly adhered to the exposed core portion in accordance with the step between the insulating portion and the exposed core portion. It is a feature. Heat generated by various electrical components mounted on the circuit board is collected at the core portion of the circuit board to equalize the heat and efficiently radiated through the heat pipe.
[0015]
Moreover, the electrical junction box according to claim 2 of the present invention uses a locking member having good thermal conductivity that makes contact between the exposed core portion and the heat pipe to contact the exposed core portion and the heat pipe. It is characterized by that. Heat transfer is performed not only through the close contact portion between the exposed core portion and the heat pipe, but also through a locking member with good thermal conductivity, so that heat is efficiently dissipated.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an electrical junction box 10 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an electrical junction box 10 according to an embodiment of the present invention includes printed circuit boards 11 and 12 on which heat generating electrical components and other electrical components are mounted, and partially on the printed circuit boards 11 and 12. The heat pipes 21 and 22 that are in close contact, the board cases 13 and 14 that are attached to the printed circuit boards 11 and 12, the printed circuit boards 11 and 12, and the board cases 13 and 14, respectively, The lower case 15 is configured to extend and hold the heat dissipating part, the upper case 16 fitted to the lower case 15, the upper cover 17 attached to the upper portion of the upper case 16, and the like.
[0017]
As shown in FIG. 2, the printed circuit boards 11 and 12 include a plurality of heat generating electrical components such as a plurality of fuse holders 23 and relays (only the fuse holder shown) on one side of the rectangular circuit board 11 and Other electrical components are mounted, and a mounting bracket 11b for mounting to the board case 13 is mounted on the other side. In addition, the heat absorption part 21a of the heat pipe 21 is attached along a part of the peripheral edge of the printed circuit board 11, and the heat dissipation part 21b of the heat pipe 21 is attached with an elongated bent heat dissipation plate 21p. Yes. In addition, the heat sink 22p of the heat pipe 22 shown in FIG. 1 is provided with attachment holes, and attachment holes are also provided in the holder portion 15h of the lower case 15 and the holder portion 16h of the upper case 16 that hold the heat sink. The heat radiating plates 21p and 22p are attached to a vehicle body panel (not shown) and the like together with the holder portions 15h and 16h by bolts having good thermal conductivity.
[0018]
The heat pipes 21 and 22 used here are those in which the working fluid is sealed in a metal tube sealed at both ends under reduced pressure. The inside working fluid is attached to the heat absorption part (attached to the printed circuit board). Side), the vaporized working fluid moves to the low-temperature heat-dissipating part side (heat-dissipating plate mounting side), liquefies by heat dissipation in the heat-dissipating part, and then returns to the heat-absorbing part side. It is a heat pipe.
[0019]
As shown in detail in FIG. 3, the printed circuit board 11 includes a core portion 11c made of a metal plate, insulating layers 11a and 11b made of glass epoxy resin sandwiching the core portion 11c, and an insulating layer. It is comprised from the conductor pattern (not shown) etc. which were formed in the surface of 11a, 11b. The core portion 11c may be any metal material that is excellent in thermal conductivity, such as aluminum, aluminum alloy, copper, copper alloy, or the like.
[0020]
The insulating layers 11a and 11b covered on the surface of the core portion 11c are prepregs in which a glass cloth is impregnated with an epoxy resin. Preferably, alumina powder or the like is mixed in the epoxy resin. Thereby, the thermal conductivity of the insulating layer 11a is improved, and the heat generated by the electrical component can be efficiently transmitted to the core portion 11c.
The conductor pattern on the surface of the insulating layer is, for example, a copper foil of 18 to 210 μm, and a predetermined circuit pattern is formed on the surface of the insulating layer 11a. Further, a resist layer (not shown) made of an epoxy-based coating material is further formed to prevent oxidation of the conductive layer and soldering.
[0021]
One side of the printed circuit board 11 (on the side where the heat pipe is attached) is a predetermined place (four places in FIG. 2). As shown in FIG. 3, a part of the insulating layer 11a is removed, and a core made of a metal plate The part 11c is exposed. The heat pipe 21 is attached along a part of the peripheral edge of the printed circuit board 11 so that the heat absorbing portion 21a of the heat pipe 21 is in direct contact with the exposed core portion 11c. More specifically, as shown in FIG. 3, a flexible clip (locking member) 31 having a U-shaped cross section is fitted into each exposed core portion 11c shown in FIG. The heat pipe 21 is brought into close contact with the printed circuit board 11 by the holding force. The clip 31 is made of a metal material having excellent thermal conductivity, such as aluminum, an aluminum alloy, copper, or a copper alloy.
[0022]
Next, the operation based on this configuration will be described.
The heat generated by the electrical components such as the fuse holder 23 and the relay mounted at different positions on the printed circuit board 11 passes through the epoxy resin in the vicinity of the respective electrical components shown in FIG. Is transmitted to. Since the core part 11c is made of a metal plate having excellent thermal conductivity, the transmitted heat is soaked by the core part 11c and is transferred to the heat pipe 21 from the part where the insulating layer 11a is removed. Heat transfer is performed at the portion in close contact with the heat pipe 21, and at the same time, heat transfer is performed from the core portion 11 c to the heat pipe 21 via the clip 31 having excellent thermal conductivity, so that the heat of the core portion 11 c is heated. Heat can be efficiently transferred to the heat absorbing portion 21a of the pipe 21. The heat transmitted to the heat absorbing portion 21a of the heat pipe 21 is radiated to a vehicle panel (not shown) to which the heat radiating plate 21p is fixed via the heat radiating portion 21b and the heat radiating plate 21p of the heat pipe 21 shown in FIG. The
[0023]
On the other hand, also with respect to the printed circuit board 12, a core part (not shown) made of a metal plate is exposed by removing a part of the insulating layer in the same manner as the above-described printed circuit board 11, and the exposed core part is exposed to the exposed core part. The heat absorption part of the heat pipe 22 is in close contact with the clip. Then, the heat generated by the electrical components mounted on the printed circuit board 12 is radiated to the outside of the electrical junction box 10 via the heat pipe 22 and the heat radiating plate 22p in the same manner as described above.
[0024]
In this way, the heat generated by the electrical components such as the fuse holder and the relay mounted on the circuit board 11 is transferred to the core portion 11c of the circuit board 11 to equalize the heat, and directly or from the exposed core portion 11c. It can be transmitted to the heat pipe 21 through the excellent clip 31 and can be directly radiated from the heat radiating plate 21p attached to the heat pipe 21 to the vehicle panel or the like outside the electric junction box. Therefore, it is not necessary to perform heat transfer with poor heat collection efficiency such as heat transfer from the insulating layer of the printed circuit board to the heat pipe via the bracket. In addition, since it is not necessary to provide heat dissipating fins for each heat generating electrical component, the number of components can be reduced, which contributes to a reduction in assembly man-hours and cost reduction. Furthermore, since high-density mounting of electrical components on the printed circuit board is possible, the electrical junction box itself can be downsized.
[0025]
In addition, since the printed circuit board has a core portion made of a metal plate, it is difficult for the conductor pattern to peel off from the printed circuit board due to thermal effects, and the electrical connection box is Can be installed in harsh locations.
Unlike the above-described embodiment, the clip may be fixed to the printed circuit board with screws or the like. Needless to say, the heat-generating electrical components are not limited to fuse holders, relays, and the like, and may include various components such as capacitors and transformers.
[0026]
【The invention's effect】
As described above, the electrical junction box according to the present invention is an electrical junction box in which a circuit board having a metal core portion and an insulating portion sandwiching the core portion in a sandwich shape is housed in a casing , the insulating portion of the substrate, is characterized in that the core portion is partially removed toward from the circuit board edge on the inside is exposed.
[0027]
Heat generated by electrical components such as a fuse holder and a relay mounted on the circuit board is collected in the core part of the circuit board to equalize the heat, and the heat can be radiated from the exposed core part. Therefore, unlike the conventional electrical junction box, it is not necessary to provide the heat-generating fins for each heat generating electric component, and the high-density mounting of the electric components is possible, and the circuit pattern width can be reduced.
[0028]
The electrical junction box according to the present invention is characterized in that the heat absorption part of the heat pipe is directly adhered to the exposed core part. Heat generated by various electrical components mounted on the circuit board is collected at the core portion of the circuit board to equalize the heat and efficiently radiated through the heat pipe. Therefore, it is possible to reduce the size of the electrical junction box and improve durability.
[0029]
Moreover, the electrical junction box according to claim 2 of the present invention uses a locking member having good thermal conductivity that makes contact between the exposed core portion and the heat pipe to contact the exposed core portion and the heat pipe. It is characterized by that. Heat transfer is performed not only through the close contact portion between the exposed core portion and the heat pipe, but also through a locking member with good thermal conductivity, so that heat is efficiently dissipated. Therefore, the product quality of the electrical junction box can be further improved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view schematically showing an electrical junction box 10 according to an embodiment of the present invention.
2 is an enlarged perspective view showing a printed circuit board 11 of FIG. 1. FIG.
3 is a detailed perspective view partially showing a close contact portion between the printed circuit board 11 and the heat pipe 21 of FIG. 2;
FIG. 4 is a perspective view showing a conventional exothermic electrical component 1 provided with heat radiating fins 1f.
FIG. 5 is a perspective view showing a heat pipe 2 attached to a printed circuit board via a bracket 2b.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Electrical connection box 11 Printed circuit board 11a, 11b Insulating layer 11c Core part 12 Printed circuit board 21 Heat pipe 21b Heat radiating part 21p Heat radiating plate 23 Fuse holder 31 Clip

Claims (2)

An electrical junction box that houses a circuit board having a metal core and an insulating part sandwiching the core in a sandwich shape,
The insulating portion of the circuit board is, the core portion exposed by partially removing toward from the circuit board edge inwardly cranked in accordance with the step between the core portion which has the exposed and the insulating portion An electric junction box, wherein the heat absorption part of the heat pipe is directly adhered. The adhesion between the heat pipe and the exposed core portions, and performs with good thermal conductivity locking member in contact with both the heat pipes and the exposed core portions, in claim 1 The electrical junction box described.

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