JP2001298290A - Heat radiation structure of electronic unit box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost heat-radiation structure of an electronic unit box wherein assembling work is easy for stable heat-radiation effect. SOLUTION: Related to an electronic unit box 10, an electronic unit comprising a control board 20 and a relay electrically connected together is housed in a housing case where an upper case 11 is coupled with a lower cover 23. The relay is provided on a flat plate of a heat sink provided above the control board in the housing case. A heat-radiating side wall 15b provided upright on the flat plate part along the side surface of the relay provides a plurality of ventilation holes 30 which communicate with the outside of case through upper and lower openings 12 and 16, against a side wall 11a of the facing upper case 11.

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 electronic unit box in which an electronic unit having a control board and power circuit components electrically connected to each other is housed in a housing case.

[0002]

2. Description of the Related Art Conventionally, as an electronic control unit (ECU) used in an electric wiring system of a vehicle or the like, a circuit board in which an electrically connected control board and a power circuit component are housed in a housing case. Is used. The conventional electronic unit 1 shown in FIG. 7 includes a relay board 4 as a power circuit component and an IC chip on a connection board 3 in which a bus bar circuit 2 having a plurality of connection tab terminals 2a is integrally molded in an insulating resin. The control board 5 and the like on which the components are mounted are placed and electrically connected. The electronic unit 1 is an electronic unit box housed in a synthetic resin housing case (not shown) for protection from dust, water and the like, for example, an electric connection box (junction box) placed in an engine room. And so on.

Further, a plurality of components such as the relay 4 and the control board 5 mounted on the connection board 3 are arranged as close as possible to each other in order to reduce the size of the electronic unit 1. In particular, the power circuit components such as the relays 4 have a large volume in order to withstand a large current, and most of the portions on the connection board 3 are areas for mounting the plurality of relays 4. . Therefore, the rectangular flat control board 5
As shown in FIG. 7, is mounted on the connection board 3 so as to be sandwiched between a plurality of relays 4 arranged in two rows.

The electronic unit box in which the electronic unit 1 is housed in a sealed housing case as described above has a poor heat radiation property and the relay 4 as a power circuit component.
Becomes hot due to the heat generated by the relay. Therefore, conventionally, for example, the heat of the relay 4 is radiated to the outside of the case via the connection tab terminal 2a of the bus bar circuit 2.

[0005]

However, since the heat radiation from the bus bar circuit 2 in the electronic unit 1 is localized and it is difficult to radiate the heat at a uniform temperature, a sufficient heat radiation effect cannot be obtained. . Therefore, when assembling the relay 4 on the connection board 3 and electrically connecting the terminals of the relay 4 to the bus bar circuit 2, the terminals of the relay 4 inserted through the through holes of the bus bar circuit 2 are added. After tightening, it was necessary to solder or connect by welding.

That is, in the conventional electronic unit box in which the electronic unit 1 is housed, the terminal of the relay 4 is heated to a temperature higher than the reliable temperature of the solder due to the heat generated by the relay. As a result, reliable electrical connection between the terminal of the relay 4 and the bus bar may not be maintained. Further, even if the solder of the connection portion is not heated until it is melted, solder cracks may occur due to thermal shock due to the heat generated by the relay, and the reliability of the electrical connection may be reduced.

Further, the control board 5 mounted on the connection board 3 so as to be surrounded by the plurality of relays 4 is susceptible to the radiation heat of the relays 4, so that the IC chips and the like on the board are excessively heated. In order to prevent the fluctuation of characteristics and thermal destruction caused by the rise, it is necessary to take a thermal measure such as using a ceramic substrate which is more expensive than a normal glass epoxy substrate.

Therefore, the conventional electronic unit box is
In order to guarantee a stable operation corresponding to a temperature rise due to the heat generated by the relay 4, a complicated assembling work and a complicated structure as described above are required, and there is a problem that the cost is increased. That is, an object of the present invention is to solve the above-mentioned problems, and to provide an inexpensive heat radiating structure of an electronic unit box which can be easily assembled and has a stable heat radiating effect.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is a heat radiating structure for an electronic unit box in which an electronic unit having a control board and a power circuit component which are electrically connected is housed in a housing case. The power circuit component is disposed on a heat radiator disposed above the control board disposed in the housing case, and is erected on the heat radiator along a side surface of the power circuit component. Wherein the formed heat radiation side wall portion defines a ventilation space communicating with the outside of the case through upper and lower openings formed in the storage case between the opposing side walls of the storage case. This is achieved by the heat dissipation structure of the unit box.

According to the above configuration, the heat generated by the power circuit components is first radiated to the radiator plate provided, and is released from the radiating side wall portion of the radiator plate to the air flowing through the ventilation space. The ventilation space communicates with the outside of the case through upper and lower openings, and when air flow occurs due to heat generated by the power circuit components, a natural convection that causes air flowing in from the lower opening to flow out of the upper opening is generated.

Therefore, the heat radiating side wall is uniformly and stably cooled by the air flowing through the ventilation space, so that the efficiency of radiating the heat generated by the power circuit components to the outside of the case can be improved. That is, the electronic unit box can obtain a sufficient heat radiation effect, and the power circuit component is not heated to a temperature higher than the reliable temperature of the solder.
Therefore, troublesome assembling work such as soldering after crimping the terminals of the power circuit components or connection by welding is not required, and the occurrence of solder cracks due to thermal shock can be reduced. There is no danger of lowering the reliability of dynamic connection.

Further, since the power circuit component is disposed on the heat radiating plate disposed above the control board, the control board is less likely to receive the radiant heat generated by the power circuit component. Further, since the heat flows from the bottom to the top, the control board housed in the case below the power circuit component serving as the heat generation center is hardly affected by the heat. Therefore, in combination with the improvement of the efficiency of radiating the heat generated by the power circuit components to the outside of the case, it is not necessary to use a ceramic substrate having high heat resistance as a measure against heat as the control substrate.

Preferably, the ventilation space comprises a plurality of ventilation holes defined by a plurality of partition walls protruding from the inner surface of the side wall of the housing case. In this case, since the ventilation space is defined by a plurality of ventilation holes, the flow path in each ventilation hole is narrowed, and the air flowing in the ventilation holes increases in flow velocity and becomes substantially laminar. Convection can be promoted, and the heat radiation efficiency can be further increased.

More preferably, the power circuit component comprises:
At least the flexible printed circuit board having a connection portion that is attached to at least the back surface of the heat sink and electrically connected to and fixed to the terminal of the power circuit component is electrically connected to the control board. In this case, the heat transmitted to the terminal of the power circuit component is transmitted from the terminal to the connection portion of the flexible printed circuit board adhered to the radiator plate, and is radiated to the radiator plate. Therefore, the heat of the terminal of the power circuit component, which has the highest temperature, can be uniformly and stably radiated to the heat radiating plate through the connection portion of the flexible printed circuit board attached to the heat radiating plate. It can be suppressed efficiently.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a heat radiating structure of an electronic unit box according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 is an exploded perspective view of an electronic unit box according to an embodiment of the present invention, FIG. 2 is a perspective view of a heat sink and a control board shown in FIG. 1, and FIG. 3 is an assembled state of the electronic unit box shown in FIG. FIG. 4 is a partially broken perspective view showing
FIG. 5 is a vertical sectional view of the electronic unit box shown in FIG. 3, and FIG.
6 is a cross-sectional view of the electronic unit box shown in FIG. 3, and FIG.
FIG. 4 is a horizontal sectional view of the electronic unit box shown in FIG. 3.

Electronic unit box 10 of the present embodiment
As shown in FIG. 1, after storing the electronic unit 40 in a storage case combining the upper cover 11 and the lower cover 23 made of synthetic resin, a predetermined case such as a junction box placed in an engine room is used. It is attached to the attachment part 50.

The electronic unit 40 includes a control board 20 and a relay 14 that is a power circuit component, which are electrically connected to each other, and achieves electrical connection when the electronic unit 40 is mounted on the mounting portion 50. Terminal holder 17. Further, the relay 14 is disposed on the flat plate portion 15a of the heat radiating plate 15, and the through hole 1 of the flat plate portion 15a is provided.
The terminal 14a of the relay 14 penetrating through 5c is electrically connected to the control board 20 via a flexible printed circuit board (FPC) 21 described later (see FIG. 4).

As shown in FIGS. 1 and 2, the heat radiating plate 15 is made of an aluminum alloy plate or the like having a high thermal conductivity, and has a flat plate portion 15a on which a plurality of relays 14 arranged in two rows are arranged. Are bent at substantially right angles to form a pair of heat-radiating side walls 15b, 15b along the outer surfaces of the relays 14 in the column direction.
The heat radiating plate 15 is not limited to the aluminum alloy, and various materials having high thermal conductivity can be used. For example, the heat radiating plate 15 can be integrally formed of a synthetic resin to which a metal filler is added. When the heat radiating plate 15 is made of a conductive material such as an aluminum alloy, the surface is preferably coated with a black insulating coating (insulating coating).

As shown in FIGS. 2 and 4, the flexible printed circuit board 21 has a connecting portion 21a attached to the back surface (the lower surface in the figure) of the flat plate portion 15a on which the relay 14 is provided. Circuit part 21b on which an IC chip or the like is mounted
And a flexible connecting portion 21c for electrically connecting the connecting portion 21a and the circuit portion 21b. The circuit section 21b is attached to a rectangular board-shaped hard board 20a to form the control board 20.

Each land portion of the connection portion 21a is
And as shown in FIG. 5, the through-hole 1 of the flat plate portion 15a is formed.
The terminal 14a of each relay 14 and the connection tab terminal 18 of the terminal holder 17 that pass through 5c are appropriately soldered and electrically connected. Here, the connection tab terminal 1
Numeral 8 is integrally molded in a predetermined arrangement (in this embodiment, two rows) in a holder main body 17a made of insulating resin, and has a front end projecting below the holder main body 17a and a base end. Are exposed flush with the upper surface of the holder body 17a.

As shown in FIG. 4, the control board 20 is turned so as to be substantially parallel to the connecting portion 21a with the flat portion 15a interposed therebetween while bending the connecting portion 21c in a U-shape. After that, it is locked and fixed by locking claws 17b protruding from the lower surface of the holder main body 17a. That is, the relay 14 is placed on the flat plate portion 15a of the heat radiating plate 15 disposed above the control board 20.

The lower cover 23 is connected to the terminal holder 17.
The terminal accommodating portion 26 capable of accommodating each of the connection tab terminals 18 is provided. On the mounting surface side of the lower cover 23 to which the electronic unit 40 is mounted, a plurality of insertion ports 27 communicating with the terminal receiving chamber in the terminal receiving portion 26 are formed, and a locking and fixing member for locking the electronic unit 40 is provided. A stop claw 24 and a locking claw 25 for locking and fixing the upper cover 11 are protrudingly provided.

Then, when the electronic unit 40 is mounted on the mounting surface of the lower cover 23 by inserting the connection tab terminal 18 into the insertion opening 27,
The electronic unit 40 is integrally assembled to the lower cover 23 by locking both longitudinal edges of the flat plate portion 15a. In this state, when the lower cover 23 and the upper cover 11 are combined, as shown in FIG.
The engaging claw 25 is engaged with the engaging hole 19 of the upper cover 11, and the electronic unit box 10 is assembled.

Further, the electronic unit box 10 of the present embodiment accommodates the electronic unit 40 and combines the lower cover 23 and the upper cover 11 with each other.
As shown in FIG.
A heat radiation structure is defined in which a ventilation space composed of a plurality of ventilation holes 30 is defined between b and 15b facing the side walls 11a and 11a of the upper cover 11.

Each of the ventilation holes 30 is defined by a plurality of partition walls 13 projecting from the inner surface of the side wall 11a, and each of the upper openings 12 formed in the top plate of the upper cover 11.
And the lower opening 16 formed between the lower end edge of the side wall 11a and the butted portion of the lower cover 23, and communicates with the outside of the case. As shown in FIGS. 5 and 6, the end of the heat-radiating side wall portion 15b has a fitting groove 1 whose upper end is provided on the inner wall of the opposing top plate of the upper cover 11.
1b, the side edge thereof is in contact with the inner surface of the opposing side wall of the upper cover 11, and water droplets and the like entering from the upper opening 12 are discharged from the lower opening 16 without entering the relay 14 side. .

That is, according to the heat radiation structure of the electronic unit box 10 of the present embodiment, the heat generated by the relay 14 is
First, heat is radiated to the flat plate portion 15a of the radiator plate 15 provided, and each of the ventilation holes 3
It is released to the air flowing inside 0. The ventilation hole 30 communicates with the outside of the case through the upper and lower openings 12 and 16 as described above. When air flows due to the heat generated by the relay 14, the air flowing in from the lower opening 16 flows out of the upper opening 15. Causes natural convection. Therefore, the heat radiating side wall portion 15b is uniformly and stably cooled by the air flowing through the ventilation holes 30, so that the heat generated by the relay 14 can be efficiently radiated to the outside of the case.

Further, in this embodiment, the relay 14
Is attached to the back surface of the flat plate portion 15a and the relay 14
Connection part 2 electrically connected to and fixed to the terminal 14a of the
1a, the flexible printed circuit board 21 having
It is electrically connected to the control board 20. Therefore,
The heat transmitted to the terminal 14a of the relay 14 is
From 4a, the heat is transmitted to the connection portion 21a of the flexible printed circuit board 21 adhered to the flat plate portion 15a of the heat radiating plate 15, and is radiated to the flat plate portion 15a.

Therefore, the heat of the terminal 14a of the relay 14, which has the highest temperature, can be uniformly and stably radiated to the heat radiating plate 15 via the connecting portion 21a of the flexible printed circuit board 21 attached to the heat radiating plate 15. As a result, heat generation of the terminal 14a can be efficiently suppressed.

That is, the electronic unit box 10 can obtain a sufficient heat radiation effect, and the terminal 14 of the relay 14
a is not heated to a high temperature equal to or higher than the reliable temperature of the solder, and as shown in FIG.
It is only necessary to solder the terminal 14a to the land portion a.

Therefore, the electronic unit 40 of the present embodiment is
This eliminates the need for a troublesome assembling operation such as soldering after crimping the terminal 14a of the relay 14 or connection by welding, and also reduces the occurrence of solder cracks due to thermal shock. There is no danger of lowering the reliability of dynamic connection.

Further, since the relay 14 is disposed on the flat plate portion 15a of the heat radiating plate 15 disposed above the control board 20, the control board 20 is less likely to receive the radiant heat generated by the relay 14. . In addition, because the heat goes from bottom to top,
The control board 20 housed in the housing case below the relay 14, which is the center of heat generation, is hardly affected by heat.

Therefore, the control board 20 uses a ceramic board as a countermeasure against heat, as in the conventional control board 5 shown in FIG. 7, in combination with the improvement of the heat radiation efficiency of the heat generated by the relay 14 to the outside of the case. There is no need to do so, and cost increases can be suppressed.

The power circuit component, the control board, the housing case,
The configurations of the radiator plate and the ventilation space are not limited to the configurations of the above-described embodiment, and it goes without saying that various configurations can be adopted based on the gist of the present invention. For example, in the electronic unit box 21 of the above-described embodiment, the partition wall 13 serves as a ventilation space defined between the heat-radiating side wall portion 15b of the heat-radiating plate 15 and the side wall 11a of the upper cover 11 opposed thereto.
Are formed as a plurality of ventilation holes 30.

This is because the ventilation space has a plurality of ventilation holes 30.
Since the flow path in each ventilation hole 30 is narrowed and the air flowing in the ventilation hole 30 increases in flow velocity and becomes substantially laminar, the ventilation space is formed in a wide flow path without the partition wall 13. This is because the natural convection can be promoted and the heat radiation efficiency can be further improved as compared with the case where the above-mentioned configuration is adopted. Therefore, if the amount of heat generated by the power circuit components is not as large as the relay 14 in the above embodiment and it is not necessary to increase the heat radiation efficiency so much, the number of the partition walls 13 can be reduced or omitted.

A heat transfer medium such as silicon grease or mica is interposed between the lower surface of the relay 14 disposed on the flat plate portion 15a of the heat sink 15 and the surface of the flat plate portion 15a.
By bringing both members into close contact, the heat radiation efficiency from the relay 14 to the flat plate portion 15a can be increased. Furthermore, the heat sink 15 of the above-described embodiment is provided with black insulating coating to enhance heat absorption and enhance the heat dissipation efficiency of the relay 14, but is not necessarily limited to this.

The power circuit component is not limited to the relay 14, but is also effective for other heat-generating electronic components such as an FET (field effect transistor). Further, in the above-described embodiment, the connection portion 2 adhered to the back surface of the flat plate portion 15a.
Although the flexible printed circuit board 21 having the circuit board 1a, the circuit section 21b, and the connecting section 21c for electrically connecting them is used, at least the connecting section attached to the back surface of the flat plate section 15a is constituted by the flexible printed board. Alternatively, the connection portion and the control board can be electrically connected by a ribbon wire or the like. Further, it is not always necessary to use a flexible printed board.

In the above embodiment, the ventilation space formed by the plurality of ventilation holes 30 is formed by the side wall 1 of the upper cover 11.
1a and the heat-dissipating side wall 15b of the heat-dissipating plate 15, but when a deep-bottom lower cover is used for the housing case, the ventilation You can also define space.

[0038]

According to the heat dissipating structure of the electronic unit box of the present invention, the heat generated by the power circuit components is first dissipated to the heat dissipating plate provided, and the heat dissipating side wall of the heat dissipating plate is used for the ventilation space. Released into the air flowing inside. The ventilation space communicates with the outside of the case through upper and lower openings, and when air flow occurs due to heat generated by the power circuit components, a natural convection that causes air flowing in from the lower opening to flow out of the upper opening is generated.

Therefore, the heat radiating side wall is uniformly and stably cooled by the air flowing through the ventilation space, so that the heat generated by the power circuit components can be efficiently radiated to the outside of the case. That is, the electronic unit box can obtain a sufficient heat radiation effect, and the power circuit component is not heated to a temperature higher than the reliable temperature of the solder.
Therefore, troublesome assembling work such as soldering after crimping the terminals of the power circuit components or connection by welding is not required, and the occurrence of solder cracks due to thermal shock can be reduced. There is no danger of lowering the reliability of dynamic connection.

Further, since the power circuit component is disposed on the heat radiating plate disposed above the control board, the control board is less likely to receive the radiant heat generated by the power circuit component. Further, since the heat flows from the bottom to the top, the control board housed in the case below the power circuit component serving as the heat generation center is hardly affected by the heat. Therefore, in combination with the improvement of the efficiency of radiating the heat generated by the power circuit components to the outside of the case, it is not necessary to use a ceramic substrate as a heat countermeasure for the control substrate, thereby suppressing an increase in cost.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a heat sink and a control board shown in FIG.

FIG. 3 is a partially broken perspective view showing an assembled state of the electronic unit box shown in FIG. 1;

4A is a longitudinal sectional view of the electronic unit box shown in FIG. 3, and FIG. 4B is an enlarged view of a main part thereof.

5A is a cross-sectional view of the electronic unit box shown in FIG. 3, and FIG. 5B is an enlarged view of a main part thereof.

FIG. 6 is a horizontal sectional view of the electronic unit box shown in FIG. 3;

FIG. 7 is an overall perspective view of a conventional electronic unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electronic unit box 11 Upper cover 11a Side wall 12 Upper opening 13 Partition wall 14 Relay (power circuit component) 15 Heat sink 15b Heat dissipation side wall part 16 Lower opening 17 Terminal holder 20 Control board 21 Flexible printed board 23 Lower cover 30 Ventilation hole (ventilation) Space) 40 electronic unit

Claims (3)

[Claims] 1. A heat dissipation structure for an electronic unit box in which an electronic unit including a control board and a power circuit component electrically connected to each other is housed in a housing case, wherein the power circuit component is provided in the housing case. The heat-dissipating side wall portion, which is provided on the heat-dissipating plate disposed above the control board disposed on the heat-dissipating plate along the side surface of the power circuit component, faces the heat-dissipating plate. A heat dissipation structure for an electronic unit box, wherein a ventilation space communicating with the outside of the case through upper and lower openings formed in the storage case is defined between the housing unit and a side wall of the storage case. 2. The electronic unit box according to claim 1, wherein the ventilation space includes a plurality of ventilation holes defined by a plurality of partition walls protruding from an inner surface of a side wall of the housing case. Heat dissipation structure. 3. The control device according to claim 1, wherein the power circuit component is attached to at least a back surface of the heat radiating plate and electrically connected to and fixed to a terminal of the power circuit component. The heat dissipation structure for an electronic unit box according to claim 1, wherein the heat dissipation structure is electrically connected to a substrate.