JPH08275339A - Radiating structure of electric junction box with built-in electronic circuit unit - Google Patents

Abstract

PURPOSE: To make an electronic circuit board and an electric junction box small and to radiate heat effectively from an exothermic electronic device, a power transistor or the like. CONSTITUTION: An electronic circuit unit 32, in which an electronic device mounted on an electronic circuit board 19 is joined with a conductive member, is stored in an automobile junction box. Then, a metallic member 14 with high heat conductivity is joined with an exothermic electronic device like a power transistor 17 on the circuit board 19. The other end of the metallic member 14 is joined with a volt 16a for fixing the junction box 11 to a car body to radiate the heat outside from the electronic device through the volt 16a and the metallic member 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipation structure for an electric junction box having an electronic circuit unit built therein, and more particularly to efficiently dissipate heat generated by an electronic device mounted on a substrate of the electronic circuit unit. It is a thing.

[0002]

2. Description of the Related Art An electric connection box used for a wire harness for an automobile has an electronic circuit unit in which electronic equipment is mounted inside a case, and an internal circuit such as a bus bar housed inside the case is connected to an electronic circuit. In some cases, the branch circuits are densely and intensively configured. Conventionally, many electronic circuits built into this kind of electrical junction box are signal system circuits such as alarm circuits for forgetting to turn off the lamp, the electronic devices mounted on the board generate a small amount of heat, and the electronic circuits are also small current circuits. Since the calorific value was small, it was not necessary to take any heat dissipation measures.

However, in recent years, in many cases, a power transistor having functions such as a fuse and a relay integrated is mounted on a substrate of an electronic circuit, and the power transistor has a large amount of heat generation and the power transistor is large. Since the electronic circuit connected to is also a large current circuit, the amount of heat generated is large.

Therefore, it is necessary to take measures against heat dissipation. As shown in FIG. 6, the heat dissipation block 1 surrounds an electronic device A such as a power transistor which generates a large amount of heat,
A large radiator plate 2 is attached to the electronic device B.

[0005]

However, when the heat dissipation block 1 or the large heat dissipation plate 2 is attached to each electronic device on the substrate 4 of the electronic circuit unit 3 as described above, the heat dissipation block 1 and the large heat dissipation plate are provided. If there are a large number of 2, the mounting area must be taken and the substrate 4 must be enlarged, and the installation area becomes large, and since the heat dissipation block 1 and the large heat dissipation plate 2 are also large in height, the electric circuit unit 3 A large volume is required inside the electrical junction box for installation,
There is a problem that the electric junction box itself becomes large. In particular, since the electric connection box is often mounted in a narrow space of an automobile, there is a demand for downsizing the electric connection box. Furthermore, if a heat dissipation block or a large heat dissipation plate is used for each electronic device, the number of parts increases and the cost increases.

Further, even if the heat generated in the power transistor is conducted to the heat dissipation block and the large heat dissipation plate, since the heat dissipation block and the large heat dissipation plate are also housed inside the case of the electric junction box, the heat dissipation block and the large heat dissipation block are large. The heat conducted to the heat sink is only radiated to the inside of the case of the electrical junction box, and the heat is trapped inside the case and the temperature inside the case cannot be prevented from rising.

The present invention aims to solve the above-mentioned drawbacks by conducting heat generated by an electronic device having a large heat generation and radiating heat without using the above-mentioned large heat dissipation block and large heat dissipation plate. The purpose of the present invention is to prevent the junction box from increasing in size, and also to prevent heat from being accumulated in the electrical junction box and rising in temperature by radiating heat to the outside of the case of the electrical junction box.

[0008]

In order to achieve the above object, the present invention provides an electronic circuit unit having an electronic device mounted on an electronic circuit board and connected to a conductive material according to claim 1, a junction box or the like. Which is built into an electric connection box for automobiles, wherein one side of a metal piece having a high thermal conductivity is connected to the heat generating electronic equipment such as a power transistor among the above electronic equipment and the other side of the metal piece is connected. Is connected to a metal stopper that attaches the electric connection box to the vehicle body, and the heat generated in the electronic device is conducted to the vehicle body through the metal piece and the metal stopper to radiate heat. A heat dissipation structure for an electric connection box with a built-in electronic circuit unit is provided. The metal stopper also includes a reinforcing stopper that connects the electric connection box and the vehicle body.

According to a second aspect of the present invention, the heat-radiating electronic device is provided with a small radiator plate, and one side of the metal piece is connected to the small radiator plate. Provides the structure.

According to a third aspect of the present invention, the metal piece is projected to the outside of the electric connection box through a through hole provided in the case of the electric connection box, and a mounting hole for the metal stopper is formed in the protruding portion. The mounting hole is communicated with a mounting hole formed in the case of the electric junction box, the metal stopper such as a bolt is passed through the communicating mounting hole, and the metal piece is coupled to the metal stopper. The heat dissipation structure according to claim 1 or claim 2 is provided.

As the metal piece, a metal having a high thermal conductivity such as aluminum is used. Further, it is preferable that the metal piece and an electronic device such as a power transistor are connected by one-touch by sandwiching a part of the electric device between the holding pieces formed on the metal piece. It goes without saying that they may be connected by bolting, welding or the like.

[0012]

According to the heat dissipating structure of the present invention, since the electronic device having a large amount of heat generation, such as the power transistor, is connected to the metal vehicle body through the metal piece and the metal stopper, the generated heat is not generated. Heat is dissipated through the above-mentioned members, and finally the vehicle body acts as a heat dissipation plate to dissipate heat to the atmosphere outside the electrical junction box. Therefore, the generated heat does not stay inside the electric junction box, and the heat can be efficiently dissipated. Also,
Since it is not necessary to mount a large heat dissipation block and a large heat dissipation plate on the board of the electronic circuit unit as in the conventional case, it is possible to reduce the size of the board and prevent the electric junction box itself from increasing in size.

When a small heat sink is attached to the electronic device according to the second aspect and the small heat sink is connected to the metal piece, the flat small heat sink and the metal piece can be easily connected and contact is made. The area can be increased, the thermal conductivity can be improved, and heat can be dissipated more efficiently.

According to the heat dissipating structure of the present invention, the metal piece is fixed to the electric connection box by the metal stopper for fixing the electric connection box to the vehicle body. Is done. As described above, as a means for fixing the metal piece to the electric junction box and a means for bringing the metal piece into contact with the vehicle body, a metal stopper made of bolts or the like for fixing the vehicle body without requiring a special member. Since only the metal pieces are specially provided, the number of parts for heat dissipation can be reduced.

[0015]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. In the junction box 11 of the first embodiment shown in FIG. 1, the bus bars 22 are laminated and arranged over the entire area of the case consisting of the upper case 12 and the lower case 13 via the insulating plate 21. The electronic circuit unit 32 is arranged on one upper side (the upper right side in the figure) of the bus bar arrangement portion, and therefore, the upper case 12
Has a shape having a stepped protrusion 12a on the upper right side as shown in the figure.

The junction box 11 is locked with the upper case 12 and the lower case 13 assembled together. In this state, the pair of mounting arms 1 protruding from both sides of the edge of the step-like protruding portion 12a of the upper case 12
The mounting hole 12c formed at the tip of 2b is brought into contact with the metal frame 15 forming a part of the vehicle body, and the metal bolt 1
6a is fixed by being screwed into a bolt hole formed in the metal frame 15 via a washer 16b.

An electronic circuit unit 32 arranged inside the stepped protrusion 12a on the side where the vehicle body mounting arm 12b is provided.
As shown in FIGS. 2 and 4, the electronic device such as the power transistor 17 is mounted on the substrate 19, and these are connected to the electronic circuit 20 formed on the lower surface and the upper surface of the substrate 19. The electronic circuit 20 is connected to a bus bar 22 and is connected to an external circuit such as a wire harness via the bus bar 22. The connection between the electronic circuit 20 and the bus bar 22 is
A required circuit 22c of the bus bar 22 is extended to one side of the lower surface of the substrate 19, and tabs 22a are formed by bending the tabs 22a upward at the tip thereof, and these tabs 22a are mounted on the upper surface of the substrate 19 through mounting holes formed in the substrate 19. It is inserted into each tab insertion portion of the connector 23 mounted on. The connector 23 accommodates terminals (not shown) connected to an electronic circuit, and these terminals are brought into contact with the tabs 22a to make electrical connection.

The power transistor 17 has a structure in which a fuse element and the like are densely integrated in addition to a relay element for performing switching control, is connected to a high-current electronic circuit, and generates a large amount of heat when energized. .

The heat generated by the power transistor 17 is, as shown in FIGS. 2 and 3, a small heat radiating plate 18 attached to the power transistor 17, a metal piece 14 connected to the small heat radiating plate 18, and the above metal-made metal. It conducts to the metal frame 15 of the vehicle body through the bolt 16a and radiates heat to the atmosphere.

As shown in FIG. 3, the metal piece 14 is made of a metal having a high thermal conductivity, such as aluminum,
A flat portion 14a arranged on the upper surface of the step-like protruding portion 12a of the upper case 12, and an inclined portion 1 arranged along one surface of one side of the flat portion 14a along the upper surface of one mounting arm 12b.
4b and a pair of holding pieces 14 that are bent downward from the other side of the projecting portion 14c and the flat portion 14a.
The holding pieces 14d and 14e are sandwiched and attached to a small heat sink 18 attached to the power transistor 17. The metal piece 14 having the above shape is formed by bending one metal plate. A mounting hole 14f is formed in the inclined portion 14b at a position communicating with the mounting hole 12c of the mounting arm 12b. The small radiator plate 18 is a rectangular flat plate made of aluminum or the like, and is attached to the power transistor 17 so as to rise vertically from the upper surface of the substrate 19.

The protruding portion 14c of the metal piece 14 is exposed to the outside of the case, and the pair of holding pieces 14d and 14e are inserted into the case through a through hole 12e provided in the upper surface of the upper case 12. Insert the holding pieces 14d and 14e into the through hole 12
It is set so that when it is inserted from e, it is located at the arrangement position of the small heat dissipation plate 18.

The pair of sandwiching pieces 14d and 14e are displaced in the longitudinal direction X of the small heat sink 18 attached to the power transistor 17 and in the Y direction orthogonal to X, the plate thickness of the small heat sink 18. It is formed by shifting the following dimensions. Therefore, the sandwiching pieces 14d and 14e contact the small heat dissipation plate 18 on both sides while being displaced from each other, and press and sandwich the small heat dissipation plate 18 from both sides to fix the sandwiching pieces in a large contact area. Can be connected with one touch.

The size of the small heat sink 18 and the heat sink 1
The size of the sandwiching pieces 14d and 14e of No. 4 is set according to the amount of heat generation of the power transistor 17, and the larger the small radiator plate 18 and the sandwiching pieces 14d and 14e are,
The contact area between the sandwiching pieces 14d, 14e and the small heat dissipation plate 18 is increased, and as a result, the thermal conductivity can be increased and the heat dissipation effect can be enhanced.

The heat conducted from the power transistor 17 to the metal piece 14 via the small heat sink 18 is applied to the bolt 16a.
Is transmitted to the vehicle body via. The connection between the metal piece 14 and the metal bolt 16a and the attachment of the metal piece 14 to the junction box 11 are performed by the junction box 11
This is performed in accordance with the work of mounting the vehicle body on the metal frame 15. That is, the small heat sink 18 is sandwiched and connected by the sandwiching pieces 14d and 14e of the metal piece 14 inserted in the case, and the mounting hole 14f of the metal piece 14 and the mounting hole 12c of the upper case 12 are communicated with each other. State, mounting holes 14f, 12c
When the bolt 16a is screwed into the screw hole of the metal frame 15 through the washer 16b, the washer 16b, into which the bolt 16a is inserted, comes into close contact with the inclined portion 14b of the metal piece 14.

With the above configuration, the power transistor 1
Since the heat of 7 is conducted to the vehicle body through the small heat sink 18, the metal piece 14, and the metal bolt 16a to be radiated,
It is possible to efficiently dissipate heat without being trapped in the junction box 11 as in the conventional case. Further, since the protruding portion 14c of the metal piece 14 is exposed to the outside of the case, heat can be radiated into the air at the protruding portion 14c as well, and the heat radiation efficiency can be further improved. The size of the protruding portion 14c is set to an appropriate size in consideration of the amount of heat to be radiated and the material cost.

Further, since the vehicle body mounting side of the junction box 11 is the side on which the board 19 of the electronic circuit unit 32 is installed, the distance between the power transistor 17 and the mounting hole 12c of the upper case 12 becomes short. ,
As a result, heat can be quickly radiated to the vehicle body, and the metal piece 14 can be made smaller, so that the material cost can be reduced.

FIG. 5 shows a second embodiment, in which the power transistor connecting portion 24a of the metal piece 24 is directly connected to the power transistor 17 without a small heat sink. The connecting portion 24a of the metal piece 24 is fixed to the power transistor 17 with the bolt 25 so as to be in contact with the power transistor 17 with the largest possible contact area. In the second embodiment, since the metal piece 24 is directly connected to the power transistor 17, it is possible to eliminate the conventional heat radiating plate and heat radiating block, and the substrate 19 and the junction box 11 are miniaturized accordingly. can do.

Although the metal piece 24 and the power transistor 17 are connected by the bolt 25 in the second embodiment, when the side surface of the power transistor 17 is a metal surface, the metal piece 24 and the power transistor 17 are connected to each other. May be connected by welding.

[0029]

As is apparent from the above description, in the heat dissipation structure of the electric connection box with the built-in electronic circuit unit according to claim 1 of the present invention, the heat of the electronic device is transmitted through the metal piece and the metal stopper to the vehicle body. It can be dissipated into the atmosphere by being used as a heat sink for the vehicle body. Therefore, it is possible to prevent heat from staying inside the electric junction box. Moreover, unlike the conventional case, it is not necessary to provide a large heat dissipation block or a large heat dissipation plate, and as a result,
Space can be saved and the electronic circuit board and the electric junction box can be downsized by the size of the heat sink, or by the removal of the heat sink block and the heat sink.

In the heat dissipation structure according to the second aspect of the present invention, by attaching the small heat dissipation plate to the electronic device, it is possible to increase the contact area at the connecting portion between the small heat dissipation plate and the metal piece, and further improve the heat dissipation efficiency. You can Further, for example, even in the case of an electronic device having a complicated shape in which it is difficult to connect the metal pieces, a small heat dissipation plate is attached to the electronic device in advance, and the metal piece is connected to the small heat dissipation plate. The connecting work can be facilitated.

In the heat dissipation structure according to the third aspect of the present invention, the connection of the metal piece and the metal stopper and the attachment of the metal piece are performed together with the work of attaching the electric junction box to the vehicle body. Can be converted. Further, in the attached state, the metal piece and the metal stopper do not separate, and the connected state can be reliably retained,
The reliability can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a junction box according to a first embodiment of the present invention.

FIG. 2 is a perspective view partially showing the internal structure of FIG.

FIG. 3 is a perspective view of the metal piece of FIG.

FIG. 4 is a perspective view showing the internal configuration of FIG. 1.

FIG. 5 is a perspective view showing a partial configuration of a junction box according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing an internal configuration of a conventional junction box.

[Explanation of symbols]

 11 Junction Box 12 Upper Case 12c, 14f Mounting Hole 13 Lower Case 14, 24 Metal Piece 15 Frame 16a Metal Bolt 17 Power Transistor 18 Small Heat Sink 19 Electronic Circuit Board 20 Circuit 21 Insulation Board 22 Bus Bar

Claims (3)

[Claims] 1. An electronic circuit unit in which an electronic device is mounted on an electronic circuit board and connected to a conductive material is built in an electric connection box for automobiles such as a junction box, wherein the power transistor is one of the electronic devices. To one side of a metal piece having a high thermal conductivity, and the other side of the metal piece is connected to a metal stopper for attaching an electric connection box to a vehicle body. A heat dissipation structure for an electric junction box with a built-in electronic circuit unit, characterized in that the heat generated in (1) is conducted to the vehicle body through the metal piece and the metal stopper to dissipate the heat. 2. The heat dissipation structure according to claim 1, wherein a small heat dissipation plate is attached to the heat-generating electronic device, and one side of the metal piece is connected to the small heat dissipation plate. 3. The metal piece is projected to the outside of the electric connection box through a through hole provided in the case of the electric connection box, and a mounting hole for the metal stopper is formed in the protruding portion, and the mounting hole is formed. To communicate with the mounting hole formed in the case of the electrical junction box, and the metal stopper such as a bolt is passed through the communicating mounting hole,
The heat dissipation structure according to claim 1 or 2, wherein the metal piece is connected to the metal stopper.