JPH08275338A - Electric junction box with built-in electronic-circuit unit - Google Patents

Abstract

PURPOSE: To radiate inner heat effectively outside an electric junction box, in which a bus bar made of blanked metallic plate is joined to an electronic circuit unit, by providing a heat sink made of blanked metallic plate in a place other than the bus bar, and joining the heat sink with a heating electric apparatus. CONSTITUTION: In a junction box 11, each bus bar 22 is laminated with an insulating plate 21 in between in all spaces from an upper case 12 to a lower case 13. An electronic circuit unit 32 is provided on an upper side above the bus bar 22, and a projected stage part 12a is formed there. In an electronic circuit unit 32, a power transistor 17, and a capacitor 31 mounted on a board 19 are connected to an electronic circuit on the rear face of the board 19. The heat from the power transistor 17 is radiated through a small heat sink 18 for joining the power transistor 17 and a heat sink 14 put at a place other than the position of the bus bar 22 on the insulating plate 21. As a result, an increase in temperature at the capacitor 31 and inside the junction box can be prevented effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric connection box containing an electronic circuit unit, and more particularly, to efficiently dissipate heat generated by an electronic device mounted on a substrate of the electronic circuit unit. is there.

[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. 7, the heat dissipation block 1 surrounds the 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.

Further, 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.

The present invention is intended to solve the above-mentioned drawbacks, and a heat dissipation plate is provided by effectively utilizing the space which has been conventionally empty inside the electric junction box to prevent the electric junction box from becoming large in size. The purpose is to form the heat sink at a low cost.

[0008]

In order to achieve the above object, the present invention according to claim 1 provides an electronic circuit unit, in which an electronic device mounted on a substrate is connected to a conductive circuit on the substrate, in an electrical connection box. In the case built in the case, inside the electric connection box, a bus bar formed by punching out a metal plate is housed as an internal circuit, connected to the conductive circuit of the electronic circuit unit, and the internal circuit of the bus bar is connected. Place a heat sink formed by punching out from the metal plate in a place not provided, and contact a part of the heat sink with the heat-generating electronic device to conduct heat generated by the electronic device to the heat sink. The electric junction box with a built-in electronic circuit unit is provided.

Of the above electronic devices, a small heat dissipation plate may be attached to an electronic device such as a power transistor which generates a large amount of heat, and the heat dissipation plate may be connected to the small heat dissipation plate. (Claim 2)

Specifically, the contact portion formed by refracting from the heat radiating plate arranged on the insulating plate on which the bus bar is not arranged is projected through the through hole formed in the substrate of the electronic circuit unit, and It is preferable that a part of the electronic device or a small heat radiating plate attached to the electronic device is sandwiched between the sandwiching portions formed at the tip and connected with one touch.
(Claim 3)

The heat radiating plate is formed by punching a metal plate forming a bus bar arranged in the same layer at a portion where the bus bar is not punched. (Claim 4)

Further, according to the present invention, in claim 5, the electronic circuit unit in which an electronic device mounted on a board is connected to a conductive circuit on the board is built in a case of an electric connection box. The bus bar housed inside the connection box is connected to the conductive circuit of the electronic circuit unit, and a contact portion coated with an insulating agent is provided on a part of the circuit of the bus bar that is used only momentarily. Connect it to an electronic device or a small heat sink attached to the electronic device,
(EN) Provided is an electric connection box with a built-in electronic circuit unit configured to conduct the heat generated from an electronic device to a bus bar to radiate the heat.

[0013]

According to the electric junction box with a built-in electronic circuit unit according to the first aspect of the present invention, the heat generated in the electronic device is conducted to the heat radiating plate and has a large volume in which the bus bar is arranged from the electronic circuit unit side. The heat is transmitted to the inside of the electrical junction box and radiated. Therefore, overheating of the electronic circuit unit side can be prevented.
Further, since the heat dissipation plate is arranged at a position where the bus bar is not arranged, and the heat dissipation plate is arranged by utilizing the empty space in the past, the electric junction box does not become large.

According to the electric connection box with the built-in electronic circuit unit according to the second aspect, the heat sink is connected to a small heat sink attached to the heat-generating electronic device. Therefore, the contact area can be increased at the contact portion between the small heat sink and the heat sink. As a result, the heat conductivity from the heat-generating electronic device to the heat dissipation plate is increased, and it is possible to cope with an electronic device having a larger heat generation amount.

According to the electrical connection box of the third aspect, the projecting portion of the heat dissipation plate arranged in the same layer as the bus bar is projected onto the board through the through hole provided in the board of the electronic circuit unit, and is provided at the tip thereof. Since the sandwiching portion sandwiches and connects a part of the electronic device or a small heat sink attached to the electronic device, the heat sink can be connected with one touch. Further, it is only necessary to provide a through hole in the substrate, and it is possible to prevent the substrate from becoming larger than in the conventional case where a heat dissipation block and a large heat dissipation plate are mounted on the substrate.

According to the electrical connection box of the fourth aspect, the bus bar and the heat radiating plate arranged in the same layer are formed of a single metal plate, and the heat radiating plate is a portion where the bus bar is not punched, the bus bar. It is formed by punching from an unnecessary place for forming. Therefore, since the heat dissipation plate is formed from the portion of the metal plate which has been conventionally discarded, the metal plate can be effectively used without waste. Further, the heat sink can be formed by punching at the same time as the bus bar.

According to the electric connection box of the fifth aspect, since the circuit of the bus bar which is used only momentarily and the electronic device are brought into contact with each other through the insulating agent, the heat of the electronic device is brought into contact with the bus bar through the contact portion. Can be conducted to radiate heat. In this way, when a part of the bus bar is used as the heat dissipation plate, the heat generated by the electronic device can be effectively dissipated without providing a separate heat dissipation plate. In addition, more effective heat dissipation can be performed by using the heat dissipation plate according to the first to fourth aspects together.

[0018]

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.

In the electronic circuit unit 32, electronic devices such as the power transistor 17 and the capacitor 31 are mounted on the substrate 19, and these are connected to an electronic circuit (not shown) formed on the lower surface of the substrate 19. The electronic circuit may also be formed on the upper surface. The electronic circuit is the bus bar 2
2 and is connected to an external circuit such as a wire harness via the bus bar 22.

To connect the electronic circuit and the bus bar, specifically, a required circuit 22e of the bus bar 22 is extended to one lower surface side of the substrate 19, and a tab 22a is formed by bending the tab 22a upward at the tip thereof. The connector 2 in which these tabs 22a are mounted on the upper surface of the board 19 through the mounting holes formed in the board 19.
3 is inserted in each tab insertion portion. The connector 23 accommodates a terminal (not shown) connected to an electronic circuit,
Electrical connection is established by fitting these terminals in contact with the tabs 22a.

The power transistor 17 has a structure in which fuse elements and the like are densely integrated in addition to relay elements 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 connected to the small heat radiating plate 18 connected to the power transistor 17 with the heat radiating plate 14 arranged on the upper surface of the upper insulating plate 21 where the bus bar 22 is not arranged. Radiates heat.

As shown in FIG. 2, the heat dissipation plate 14 is a flat plate portion 1.
4a and a pair of sandwiching pieces 14b, 14c for refracting upward from one end of the flat plate portion 14a. In the example shown in FIG.
Although the flat plate portion 14a has a substantially rectangular plate shape,
Any shape may be used as long as it has a required area necessary for heat dissipation, and it is formed according to the shape of the metal plate at a portion unnecessary as a bus bar.

The pair of sandwiching pieces 14b and 14c are offset from each other 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 thickness of the small heat sink 18 is small. It is formed by shifting the following dimensions.
Therefore, the sandwiching pieces 14b and 14c are arranged so as to be displaced and abutted on the side surfaces of the small heat dissipation plate 18, and also to sandwich and fix the small heat dissipation plate from both sides in a manner having a large contact area. You can connect with.

The heat radiating plate 14 is formed by punching from the same metal plate as the upper bus bar 22 arranged in the same layer, as shown in FIG. At this time, the heat dissipation plate 14 is formed by punching out an unnecessary portion of the metal plate on which the bus bar 22 is not formed. Therefore, it is possible to effectively use the above-mentioned portion of the metal plate that has been conventionally discarded without waste. Further, since the heat dissipation plate 14 is arranged in an empty area where the bus bar 22 is not arranged, the space can be effectively used, and it is not necessary to increase the size of the junction box 11. If necessary, a heat radiating plate formed by punching the same metal plate as the bus bar is also arranged in the lower bus bar arranging layer, and the protrusion 14b is inserted through the upper insulating plate so as not to interfere with the upper bus bar. , 14c may be located and connected to the power transistor 17.

The flat plate portion 14a of the heat radiating plate 14 has the bus bar 2
The sandwiching pieces 14b and 14c, which are arranged along with the surface of the upper insulating plate 21 together with the second circuit portion, are projected onto the board 19 through the through holes 19a provided in the board 19 of the electronic circuit unit, and the small heat radiation is achieved. The plate 18 is clamped. The flat plate part 1
Since 4a is arranged in a region where the bus bar 22 is not provided, the heat dissipation plate 14 and the bus bar 22 are electrically insulated.

The size of the small heat sink 18 and the heat sink 1
The size of the sandwiching pieces 14b and 14c of 4 is set according to the amount of heat generation of the power transistor 17, and the larger the small heat sink 18 and the sandwiching pieces 14b and 14c,
The contact area between the sandwiching pieces 14b, 14c 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 of the power transistor 17 is conducted to the flat plate portion 14a on the insulating plate 21 via the small radiator plate 18 and the sandwiching pieces 14b and 14c of the radiator plate 14, and to the space on the side where the large-capacity bus bar is arranged. Heat is dissipated. Therefore, it is possible to efficiently dissipate heat without providing a large heat dissipation block or a large heat dissipation plate on the substrate 19 as in the conventional case.

FIG. 4 shows a second embodiment in which the shape of the connecting portion of the heat sink to the small heat sink is changed. In the heat radiating plate 24 of the second embodiment, a contact piece 24b that is in surface contact with one side of the small heat radiating plate 18 is formed by bending upward from one edge of the flat plate portion 24a and is formed at a right angle from one edge of the contact piece 24b. An L-shaped holding piece 24c that bends to the
A pressing portion 24d is provided on the inner surface of the upper end of c.

The connection between the heat sink 24 and the small heat sink 18 is
The small heat dissipation plate 18 is sandwiched between the contact piece 24b of the heat dissipation plate 24 and the sandwiching piece 2
4c is inserted from above in FIG. 4, and the inserted small heat dissipation plate 18 is pressed by the pressing portion 24d toward the contact piece 24b side to be sandwiched.

FIG. 5 shows a third embodiment, in which a heat radiating plate is not provided separately from the bus bar 22 and the circuit portion 22b of the bus bar 22 which is used only momentarily is used as a heat radiating plate.
That is, at one end of the circuit portion 22b, a pair of sandwiching pieces 22c, 22c, similar to the sandwiching pieces 14b, 14c of the heat dissipation plate 14 of the first embodiment.
22d is provided, the small heat dissipation plate 18 is sandwiched by the sandwiching pieces 22c, 22d to connect the bus bar 22 and the small heat dissipation plate 18, and the heat of the power transistor 17 is transferred to the circuit portion 22b of the bus bar 22.
It conducts heat to and radiates heat. An insulating agent 33 is applied to the contact surfaces of the sandwiching pieces 22c and 22d with respect to the small heat dissipation plate 18, so that the sandwiching pieces 22c and 22d and the power transistor 17 are insulated from each other.

By using a part of the bus bar 22 as described above, the heat of the power transistor 17 can be radiated by using the bus bar 22 even when there is no space for providing the heat dissipation plate 14.

FIG. 6 shows a fourth embodiment in which the power transistor connecting portion 34a of the heat sink 34 is directly connected to the power transistor 17 without the small heat sink 18. The connecting portion 34a of the heat dissipation plate 34 has a contact area as large as possible and is projected from the flat plate portion 34b. The connecting portion 34a is fixed by a bolt 35 in a state of being in close contact with the entire side surface of the power transistor 17.

As described above, since the heat dissipation plate 34 is directly connected to the power transistor 17, it is not necessary to connect a small heat dissipation plate to the power transistor 17, and the number of parts and the number of mounting steps can be reduced.

In the fourth embodiment, the heat sink 34 and the power transistor 17 are connected by the bolt 35. However, when the side surface of the power transistor 17 is a metal surface, the heat sink 34 and the power transistor 17 are connected to each other. You may connect by welding.

In each of the above-described first to fourth embodiments, the heat sink is connected to the power transistor 17, but the heat sink is not limited to the power transistor and is also connected to an electronic device that generates a large amount of heat. It goes without saying that heat dissipation can be achieved.

[0037]

As is apparent from the above description, in the electric connection box with the built-in electronic circuit unit according to claim 1 of the present invention,
Since it is not necessary to attach a large-sized heat dissipation block or a large heat dissipation plate to a heat-generating electronic device as in the related art, the electronic circuit unit and the electric junction box can be downsized.
Further, since the heat sink of the present invention is arranged in a place where the circuit portion of the bus bar is not provided, that is, in an empty area, the heat sink can be provided without enlarging the electric junction box, and the electric junction box becomes large. Can be prevented. In addition, the large number of parts can be reduced by eliminating the need for large heat dissipation blocks and large heat dissipation plates as in the past.
Cost reduction can be achieved.

In the electric connection box with the built-in electronic circuit unit according to the second aspect, since the heat sink is connected to the small heat sink attached to the heat-generating electronic device, at the contact portion between the small heat sink and the heat sink. The contact area can be increased. As a result, the heat conductivity from the heat-generating electronic device to the heat dissipation plate is increased, and it is possible to cope with an electronic device having a larger heat generation amount.

In the electric connection box with the built-in electronic circuit unit according to the third aspect of the present invention, the heat dissipation plate is a sandwiching portion provided in the protruding portion protruding through the through hole provided in the substrate, and is a part of the electronic device or the electronic device. It is connected to electronic equipment by sandwiching a small heat sink attached to the board, so it is only necessary to provide a through hole in the board, space can be saved on the board, and the heat sink can be downsized with one touch. It can be connected to a heat sink.

In the electric connection box with the built-in electronic circuit unit according to the fourth aspect, since the heat sink is formed from the portion of the metal plate which has been conventionally discarded, the metal plate can be effectively used without waste. Therefore, the material cost can be reduced, and the heat sink can be manufactured at low cost.

In the electric connection box with the built-in electronic circuit unit according to the fifth aspect, since a part of the bus bar is used as a heat dissipation plate, it is not necessary to provide a special heat dissipation plate.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a configuration of a heat dissipation plate provided in the junction box of FIG.

FIG. 3 is a plan view showing a state where a bus bar and a heat dissipation plate are punched out from a metal plate.

FIG. 4 is a perspective view showing a configuration of a heat dissipation plate according to a second embodiment of the present invention.

FIG. 5 is a partially cutaway perspective view showing a configuration of a sandwiching piece provided on a bus bar according to a third embodiment of the present invention.

FIG. 6 is a perspective view showing a connected state of a heat sink and a power transistor according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a configuration of a conventional large heat dissipation block and a large heat dissipation plate attached to a power transistor.

[Explanation of symbols]

 11 junction box 14,24,34 heat sink 17 power transistor 18 small heat sink 19 substrate 19a through hole 21 insulating plate 22 bus bar 32 electronic circuit unit

Claims (5)

[Claims] 1. An electronic circuit unit in which an electronic device mounted on a board is connected to a conductive circuit on the board is built in a case of an electric connection box, wherein a metal plate is provided inside the electric connection box. A bus bar formed by punching is housed as an internal circuit, and is connected to a conductive circuit of the electronic circuit unit, and at a location where the internal circuit of the bus bar is not provided, a heat dissipation plate formed by punching from the metal plate is arranged, An electric connection box with a built-in electronic circuit unit, wherein a part of the heat dissipation plate is brought into contact with the electronic device having heat generation to conduct heat generated from the electronic device to the heat dissipation plate. 2. The electric circuit with a built-in electronic circuit unit according to claim 1, wherein a small heat radiating plate is attached to the electronic device having a large heat generation amount, and the heat radiating plate is connected to the small heat radiating plate. Connection box. 3. A contact portion formed by refracting from the heat dissipation plate is projected through a through hole formed in a substrate of an electronic circuit unit, and a holding portion formed at a tip of the projection portion is provided with a part of the electronic device or The electrical connection box with a built-in electronic circuit unit according to claim 1 or 2, wherein a small heat dissipation plate attached to an electronic device is sandwiched and connected. 4. The heat radiating plate according to claim 1, wherein the heat radiating plate is formed by punching from a metal plate forming a bus bar arranged in the same layer at a portion where the bus bar is not punched. Electrical connection box with built-in electronic circuit unit. 5. In a case where an electronic circuit unit in which an electronic device mounted on a board is connected to a conductive circuit on the board is built in a case of an electric connection box, a bus bar to be housed inside the electric connection box is provided. , A small-sized part which is connected to the conductive circuit of the electronic circuit unit and is provided with a contact part coated with an insulating agent on a part of the circuit of the bus bar which is used only momentarily, and the contact part is attached to the electronic device or the electronic device. An electrical junction box with a built-in electronic circuit unit that is connected to a heat sink to conduct the heat generated by electronic equipment to the bus bar and dissipate the heat.