JPH0767231A - Heat dissipation structure for electric joint box - Google Patents

Abstract

PURPOSE:To prevent functional trouble and fusion due to heat without increasing cost or occupying space by suppressing temperature rise through a simple structure of substantially same size as conventional one. CONSTITUTION:In the heat dissipation structure for electric joint box containing an electric circuit, i.e., a heat source, the front cover 31 to be fixed detachably to the opening of the body employs a double structure having inner hollow section 31a. A cooling liquid 35 is encapsulated in the hollow section 31a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric junction box having an electric circuit serving as a heat source contained therein, and more particularly to a heat dissipation structure for effectively discharging the generated heat to the outside.

[0002]

2. Description of the Related Art An electrical connection box used for wiring automobiles, for example, has an electric component internally provided therein and accommodates an electric circuit connected to the electric component. FIG. 5 is a perspective view of a conventional electric junction box. Parts such as a fuse 3 and a relay 5 are internally provided in the box-shaped main body 1, and a front cover 7 for waterproofing and dustproofing is detachably attached to an opening of the main body. An electric wire 9 for input and output for forming a predetermined circuit is connected to the fuse 3, the relay 5, etc., and the electric wire 9 is drawn out from a through hole 13 formed in the back cover 11 to the outside. However, in the electrical junction box configured in this way, as the number of electrical components increases, the packing density increases due to restrictions on the mounting space,
There is a possibility that heat may be generated from the electric circuit body, the electric wire connecting portion, the fusible portion of the fuse, the coil, and the like, and functional damage or melting damage may occur in the component and the main body 1.

For solving this kind of problem, for example,
An electric connection box equipped with an electric fan is proposed in Japanese Utility Model Laid-Open No. 3-91014. FIG. 6 is a perspective view of a back cover to which an electric fan is attached. In this conventional example,
An electric fan 15 for intake or exhaust is provided on the back cover 11. According to the electrical junction box according to this conventional example,
When the electric fan 15 is driven, the air passes through the gaps and the through holes 13, and the air heated in the main body 1 is forcibly replaced with outside air having a low temperature, so that the temperature in the main body 1 may be lowered. did it.

As another conventional example, an actual flat type 3
There is an electric junction box using a heat pipe described in Japanese Patent Publication No. -97318. FIG. 7 is a sectional view of a conventional electric junction box using a heat pipe. In this example, the through hole 1 is formed in the front cover 7.
7 is bored, and the heat pipe 1 is penetrated through the through hole 17.
9 is attached. The heat pipe 19 is a heat collecting plate 21.
The heat absorbing portion 19a having the heat radiation portion 19a is arranged inside the main body 1, while the heat radiation portion 19b having the heat radiation fins 23 is arranged outside the main body 1. According to the conventional electrical junction box, the working fluid in the heat pipe 19 absorbs the heat generated in the main body 1 by the heat absorbing portion 19a and is vaporized, and is liquefied by radiating the heat in the heat radiating portion 19b, and the heat absorbing portion 19a is again formed. By repeating this process, the heat could be efficiently discharged to the outside.

[0005]

However, in the electric junction box to which the electric fan is attached, the driving of the electric fan 15 may cause noise, and the use of the driving parts causes a problem of life. Further, in this conventional example, since the outside air is forced to flow into the main body 1 by the electric fan 15, there is a drawback that dust, water, etc. easily enter, and the electric fan 15 must be additionally installed. Therefore, there is also a drawback that the volume of the electric junction box becomes large. On the other hand, in the electric junction box using the heat pipe, the expensive heat pipe 19 is used, which increases the cost and secures the cooling space for disposing the heat dissipation portion 19b outside the electric junction box. I had to do it, which was against the space saving. The present invention has been made in view of the above situation, provides a heat dissipation structure for an electric connection box that is substantially the same size as a conventional electric connection box, and that can suppress a temperature rise with a simple structure. The purpose is to prevent functional damage and melting damage due to heat generation without significantly increasing the occupied space.

[0006]

To achieve the above object, a heat dissipation structure for an electric junction box according to the present invention is an electric connection in which an electric circuit serving as a heat source is housed inside a box-shaped main body having an opening. In the heat dissipation structure of the box, the front cover detachably attached to the opening of the main body is formed in a double structure having a hollow part inside, and the cooling liquid is enclosed in this hollow part. is there. Further, the heat dissipation structure may be a double structure in which at least a part of the front cover has a hollow portion, and the cooling liquid is enclosed in the hollow portion. Furthermore, in the heat dissipation structure, it is preferable that heat dissipation fins be provided on the outer peripheral surface of the front cover.

[0007]

When heat is generated in the main body, the heat of that portion is conducted to the cooling liquid and is conducted to the entire cooling liquid. As a result, the entire cooling liquid reaches the thermal equilibrium temperature, and the heat generated in a certain part of the main body is diffused and cooled. At the same time, the cooling liquid is moved by heat convection, and the new low-temperature cooling liquid is constantly in contact with the heat transfer surface.
The effect of heat dissipation is obtained. If a part of the front cover has a double structure, it is possible to more easily configure the structure having the above-described operation. Further, if the fins for heat dissipation are provided on the outer peripheral surface of the front cover, the efficiency of heat dissipation to the outside air becomes higher.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a heat dissipation structure for an electric junction box according to the present invention will be described in detail below with reference to the drawings. 1 is a sectional view showing a heat dissipation structure of an electric junction box of the present invention, FIG. 2 is a perspective view of the electric junction box, FIG. 3 is a sectional view taken along the line AA of FIG. 2, and FIG. is there. As shown in FIG. 3, the box-shaped front cover 31 has a double structure having a hollow portion 31a inside, and the outer surface of the front cover 31 has a hollow portion 31a.
Is provided with a cooling liquid inlet 33 (see FIG. 2). As shown in FIG. 1, the cooling liquid 35 is injected into the hollow portion 31a, and the cooling liquid 35 is sealed in the hollow portion 31a by fixing the rubber plug 37 to the cooling liquid injection port 33. ing. In addition, as a method for manufacturing the above-mentioned front cover 31 in a double structure, as shown in FIG.
The method of inserting the inner wall 31c into b and performing the injection molding, or the outer wall 3
A method of heat welding the inner wall 31c and the inner wall 31c may be considered. Further, as the above-mentioned cooling liquid 35, water (H ₂ O), which has a large thermal conductivity and is easy to handle, is one of the preferable liquids among the liquids. The front cover 31 thus configured is detachably attached to the opening of the main body 1 (see FIG. 5),
The heat dissipation structure of the electrical junction box according to this embodiment is configured.

Next, the operation of the heat dissipation structure of the electrical junction box thus constructed will be described below. When heat is generated in a certain part in the main body 1, the heat in that part passes through the inner wall 31c and is conducted to the cooling liquid 35 in that part. As a result, the heat conducted to that portion is conducted to the entire cooling liquid 35. That is, when high-temperature molecules and low-temperature molecules are formed in the cooling liquid 35, the molecular motion of the high-temperature molecules is transmitted to the adjacent low-temperature molecules, the kinetic energy of the high-temperature molecules is reduced accordingly, and the temperature is lowered. On the other hand, the low-temperature molecule receives kinetic energy, and the temperature rises accordingly. This occurs during the entire volume of the cooling liquid 35 (for example, between the heat generating portion and the side wall portion distant from the heat generating portion), so that the whole becomes the thermal equilibrium temperature. And this heat is applied to the outer wall 3
As a result, the main body 1
The heat generated in a certain part of the inside is diffused and cooled. Further, the above-described action is only from the viewpoint of heat conduction, but if the heat generating portion is located below in the gravitational field, the cooling liquid 35 will move due to heat convection at the same time. That is, the cooling liquid 35 in the high temperature portion expands and its density decreases, so that it becomes lighter and moves upward. After that, the low-temperature cooling liquid 35 near by flows in and fills up the after. In this way, the new low-temperature cooling liquid 35 is constantly in contact with the heat transfer surface to exchange heat with the heat transfer surface.
The effect of heat dissipation will be obtained.

According to the heat dissipation structure of the electrical junction box according to the above-mentioned embodiment, the temperature rise is suppressed and the front cover 31 has the double structure, so that the warpage of the product seen in the conventional front cover is alleviated. In addition, the rigidity of the cover itself can be improved. Further, in the unlikely event that a fire occurs from inside the electrical junction box, the resin of the front cover 31 is melted, and the enclosed cooling liquid 35 flows out to bring about an effect of extinguishing the fire.

Although the cooling liquid inlet 33 is provided on the upper surface of the front cover 31 in the drawing, it may be provided on the side portion, the inner surface of the upper portion, or the inner surface of the side portion. Furthermore, front cover 3
The double structure portion 1 has the same effect as described above even when only the upper surface or only the side surface is provided. Also, front cover 3
Although a large amount of heat transfer can be obtained by heat conduction and convection in the inside of No. 1, the outer surface and the inner surface of the front cover 31 have a normal heat transfer mode. It is also conceivable to provide a heat radiation / heat absorption means such as fins on the inner surface.

In the heat dissipation structure of the electrical junction box according to the above-described embodiment, the cooling liquid 35 is enclosed in the double structure of the front cover 31 to obtain the heat dissipation effect by heat conduction and heat convection. In the front cover 31, if a high-temperature portion close to the heat generating portion and a low-temperature portion that is not so can be determined in advance, a so-called wick is provided in the double structure of the front cover 31 to transport the cooling liquid 35. It is also possible to improve efficiency. That is, a transport path for the cooling liquid 35 is formed in the double structure of the front cover 31 with a fibrous or porous substance, and one end of this transport path is opened to a high temperature portion in the double structure and the other end is formed. To the low temperature part and open the wick on the front cover 3
It is formed within 1. With such a structure, the heat transmitted from the high temperature portion is cooled by the cooling liquid 35 in the wick.
Is boiled and evaporated, and the cooling liquid 35 is transported in the form of vapor at high speed to the low temperature part, where it is condensed and becomes a liquid, permeates into the wick, and flows into the high temperature part again due to the capillary action to operate. You can get great heat transfer. That is, the same action as that of the heat pipe can be obtained within the double structure of the front cover 31, and in this case, the transportation efficiency can be improved without being affected by gravity.

[0013]

As described above in detail, according to the heat dissipation structure of the electric junction box of the present invention, when heat is generated in the main body, the heat in that part is conducted to the entire cooling liquid by heat conduction and heat convection. Will be diffused into and cooled. As a result, it is possible to suppress the temperature rise with a size that is almost the same as the conventional electrical junction box and with a simple structure, and prevent functional failures and melting damage due to heat generation without significantly increasing cost and occupied space. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a heat dissipation structure of an electric junction box of the present invention.

FIG. 2 is a perspective view of an electric junction box.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is an explanatory diagram for manufacturing a front cover.

FIG. 5 is a perspective view of a conventional electrical junction box.

FIG. 6 is a perspective view of a back cover to which an electric fan is attached.

FIG. 7 is a cross-sectional view of a conventional electric junction box using a heat pipe.

[Explanation of symbols]

 1 Body 31 Front Cover 31a Hollow 35 Liquid for Cooling

Claims (3)

[Claims] 1. In a heat dissipation structure of an electric connection box in which an electric circuit serving as a heat source is housed inside a box-shaped main body having an opening, a front cover detachably attached to the opening of the main body is hollow. A heat dissipating structure for an electric connection box, wherein the heat dissipating structure is formed in a double structure having a portion, and a cooling liquid is enclosed in the hollow portion. 2. The heat dissipation structure for an electrical junction box according to claim 1, wherein at least a part of the front cover is formed in a double structure having a hollow portion, and a cooling liquid is enclosed in the hollow portion. . 3. The heat dissipation structure for an electrical junction box according to claim 1, wherein heat dissipation fins are provided on an outer peripheral surface of the front cover.