JP2000174468A - Cooling structure of electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissipate effectively heat from a microcomputer which is subjected to surface mounting on a printed board inside a case of a bag structure, constituting an electronic control unit(ECU) to the outside of a case. SOLUTION: A heat-absorbing part 40 is formed in an inner wall surface 11c of a case 11 facing opposite and proximate to an electronic component (microcomputer) 17b with heat-generating property, which is subjected to surface mounting on a printed board 16 of an electronic control circuit 15 stored inside the case 11 of a bag structure of an ECU. Heat from the electronic component 17b with heat generating property can be cooled effectively through the heat- absorbing part 40. Reliability of an ECU can be improved by fixing the tip side of the printed board 16 by a projection part 50 and properly holding positioning relation between the heat absorbing part 40 and a surface of the electronic component 17b with heat generation property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for electronic components, and more particularly to a cooling structure for electronic components mounted in an engine room of a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a prior art document relating to a cooling structure of an electronic component, one disclosed in Japanese Patent Publication No. 5-505702 is known. In this device, heat-generating electronic components (output components such as power transistors) in an electronic control unit are replaced with heat sinks (cooling bodies).
A technique is disclosed in which the heat from an electronic component is radiated to the outside of a metal case (casing) through a frame and a plate-shaped portion.

[0003]

By the way, a microcomputer for generating a control signal for an output component is provided in the electronic control unit. This microcomputer is a one-chip type which is surface-mounted on a printed circuit board (printed wiring board). In recent years, there has been a tendency to increase the operation speed in order to increase the processing speed. For this reason, heat generation from the microcomputer has also become a problem, and when an electronic control unit incorporating this microcomputer is placed in an engine room where the thermal environment is poor, further consideration is required, and the control from the microcomputer is required. If the heat is not effectively dissipated, there is a possibility that a malfunction may occur.

To cope with this, for example, Japanese Patent Application Laid-Open
As disclosed in JP-A-125699, it is conceivable to provide a heat transfer member having good heat conductivity in close contact between the case and the surface of the microcomputer (power IC). Here, when a case having a bag structure is adopted, a printed circuit board on which a microcomputer is mounted and a heat transfer body attached to the surface of the microcomputer are inserted through an opening of the case in a process of assembling the electronic control unit. Then, the heat transfer body is pushed in contact with the inner wall surface of the case, and if the heat transfer body attached to the microcomputer surface is displaced at this time, a desired heat radiation effect cannot be obtained as a result. There was a defect.

Accordingly, the present invention has been made to solve such a problem, and the heat from a microcomputer surface-mounted on a printed circuit board in a case of a bag structure constituting an electronic control unit is transferred to a heat transfer member or the like. It is an object of the present invention to provide a cooling structure for an electronic component that can efficiently radiate heat to the outside of a case without using a separate member.

[0006]

According to the electronic component cooling structure of the present invention, the heat generation mounted along the surface of the board of the electronic control circuit housed in the case of the bag structure of the electronic control unit. A heat absorbing portion is formed inside the case so as to face and be close to the electronic component having the. For this reason, the electronic component having heat generation is efficiently cooled via the heat absorbing portion. At this time, the front end side of the substrate is fixed by the fixing portion formed inside the case, and the positional relationship between the heat absorbing portion and the surface of the heat-generating electronic component is appropriately maintained. Therefore, when the board on which the electronic components forming the electronic control circuit are mounted is housed in the case of the bag structure of the electronic control unit, the electronic control circuit does not come into contact with the inside of the case. Then, heat from the heat-generating electronic components mounted along the surface of the board of the electronic control circuit is efficiently cooled through the heat absorbing portion formed inside the case.

In the electronic component cooling structure of the present invention, the heat absorbing portion and the fixing portion are formed at the same time when the case of the electronic control unit is formed, so that the structure is not complicated.
There is no increase in cost due to an increase in the number of parts. According to the heat absorbing portion and the fixing portion formed at the same time as the case, the heat absorbing portion efficiently mounts the heat-generating electronic components mounted along the surface of the board of the electronic control circuit on the substrate, and the heat absorbing portion fixes the electronic control circuit to the board by the fixing portion. Accurate positioning is achieved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a sectional view showing a storage state of a storage box and an electronic control unit to which an electronic component cooling structure according to an embodiment of the present invention is applied. FIG.
FIG. 2 is an exploded perspective view illustrating a main configuration of the electronic control unit in FIG. 1.

1 and 2, reference numeral 10 denotes an electronic control unit (hereinafter, referred to as "ECU"). The ECU 10 is mounted on a printed circuit board 16 in a case 11 having a bag structure made of aluminum alloy die-cast. It has a substantially rectangular parallelepiped shape incorporating an electronic control circuit 15 including various electronic components 17a, 17b, and 17c. A flange 12 is formed on an outer wall surface of a case 11 of the ECU 10. The storage box 20 includes a plastic bottomed rectangular cylindrical box body 21 for housing the ECU 10 and a plastic lid 25 on the upper side thereof, both of which are sealed via a seal packing 26. A wire harness 31 penetrates the lid 25 through a rubber wire harness grommet 32 in a sealed state, and a connector 33 at the tip of the wire harness 31 is connected to the external connector 19 at the top of the ECU 10. In addition, 19a
Is a plastic case lid formed so as to cover the periphery of the external connection connector 19 arranged in the opening 11b of the case 11 of the ECU 10, and is omitted in FIG.

The ECU 21 is provided in the box 21 of the storage box 20.
The ten cases 11 are accommodated, and the flange 12 formed on the outer wall surface of the ECU 10 and the flange 22 formed on the inner wall surface of the box body 21 are in close contact with each other via a seal packing 23, and formed on the case 11 of the ECU 10. Flange 12
On the upper side, the case 11 and the box 21 of the storage box 20 are fixed by screws (not shown). With this, the ECU
A cooling airflow for cooling the ECU 10 having a waterproof property flows between an outer wall surface of the case 11 and an inner wall surface of the box 21 of the storage box 20, and an air passage 2 as a region to which the cooling air hits
4 are formed. In addition, the two flanges 1
Inside the upper lid 25 isolated by 2 and 22, there is formed an area 27 to which the cooling air does not directly hit.

FIG. 3 shows a case 11 of the ECU 10 of this embodiment.
FIG. 4 is a cross-sectional view showing a fixed state of the electronic control circuit 15 in FIG.

As shown in FIGS. 2 and 3, a printed circuit board 16 forming an electronic control circuit 15 has various electronic components 1 on it.
7a, 17b and 17c are mounted. Among them, the heat-generating electronic components (such as power transistors) 17a
Is mounted substantially vertically on the printed circuit board 16, is made of an aluminum plate or the like located near the opening 11 b side of the case 11 of the ECU 10, and is tightly fixed to the surface of the heat sink 18 having good heat dissipation properties with screws, adhesive or the like. I have. The heat sink 18 is screwed and fixed to the printed circuit board 16. Further, an electronic component (microcomputer) 17 b having a heat generating property is surface-mounted on the printed circuit board 16 so as to be located on the back side of the case 11 of the ECU 10.
Electronic components (capacitors, resistance elements, etc.) 17c that generate relatively little heat and have little thermal effect are printed circuit boards 16
The electronic components 17a and 17b having heat generation on the surface are mounted using the area where the electronic components 17a and 17b are not mounted. Furthermore, EC
An external connector 19 is soldered to the printed board 16 on the side of the opening 11b of the case 11 of U10.

The printed circuit board 16 is the case 1 of the ECU 10.
A region where the heat sink 18 is inserted into the slit grooves 13a and 13b formed so as to face the inner wall surface 11c of the ECU 1 and the cooling air above the flange 12 of the case 11 of the ECU 10 does not directly hit by using the screw holes 18a. It is fixed with a screw 14 through a through hole 11a drilled facing 27.

Next, the case 11 of the ECU 10 according to the present embodiment will be described.
The cooling structure for the heat-generating electronic component (microcomputer) 17b surface-mounted on the printed circuit board 16 will be described in detail with reference to FIGS. 3, 4, 5, and 6. FIG. Here, FIG. 4 is a sectional view showing the internal structure of the case 11 alone of the ECU 10 of the present embodiment, FIG. 5 is a top view showing the internal structure of the case 11 alone of FIG. 4, and FIG. 6 is a line AA of FIG. FIG. 6 is a partial detailed cross-sectional view showing an internal structure of the case 11 on the inner side along the line.

In FIGS. 3, 4, 5 and 6, opposed slit grooves 13a and 13b are formed in the inner wall surface 11c of the case 11 of the ECU 10 as described above. Also, on the inner wall surface 11c of the case 11 of the ECU 10, a plurality (three in this embodiment) of the surface mounted on the printed circuit board 16 is provided.
A plurality (12 in this embodiment) of heat absorbing portions 4 are opposed to the surface of the electronic component 17b having a heat generating property so as to have a slight gap.
Zeros are formed at predetermined intervals. And ECU1
A plurality (five in this embodiment) of projections 50 are provided on the bottom side of the case 11 at predetermined intervals to substantially separate the printed board 16 from the bottom of the case 11 at predetermined intervals. It is formed so as to be alternated on the front and back of the sixteen.

The reason why the heat absorbing fins 40 are formed only in the portion corresponding to the electronic component 17b having a heat generating property is so as not to hinder the mounting of other tall electronic components. The heat absorbing fins 40 and the projections 50 in the case 11 of the ECU 10 are formed at the same time when the case 11 is formed by die-casting aluminum alloy. Also,
The heat absorbing fins 40 are formed only in the portion corresponding to the heat-generating electronic component 17b on the back side of the case 11 in order to facilitate molding by aluminum alloy die casting, and are removed from the back side of the case 11 toward the opening 11b. It has a tapered shape with a gradient. Also, the slit groove 13
When the printed board 16 is inserted into the case 11 and assembled using the a and 13b, the heat-generating electronic components (microcomputer) 17b surface-mounted on the printed board 16 and the end surfaces of the heat absorbing fins 40, etc. Are not in contact with each other. Therefore, the electronic control circuit 15 does not come into contact with the inner wall surface 11c of the case 11, and the reliability in the assembly process can be improved. According to the arrangement of the ECU 10 configured as described above,
It is also effective against vibrations during running of the vehicle after being stored in the storage box 20 and mounted in the engine room.

Next, the cooling operation in this embodiment will be described with reference to FIGS. 1, 2 and 3. FIG.

The storage box 20 in which the ECU 10 of this embodiment is stored is mounted in an engine room of a vehicle (not shown), and the outside air flowing under the vehicle is stored in the storage box 2 by a duct or the like.
The cooling air flows in the direction of the arrow shown in FIG. 1 by being guided into the air passage 24 from the lower part of the zero box 21. Then, using the negative pressure near the front side of the cooling fan (not shown) of the radiator, the cooling wind in the air passage 24 is
Air is forcibly exhausted from a lateral portion of the device 1 by a duct or the like. Then, the outer wall surface of the case 11 of the ECU 10 housed in the storage box 20 is cooled by the cooling air flowing through the air passage 24, and the electronic control circuit 15 built in the case 11 is cooled.
Will be cooled. At this time, in particular, the heat-generating electronic components (such as power transistors) 17a of the electronic control circuit 15 are efficiently cooled through the heat sink 18 which is tightly fixed to the inner wall surface 11c of the case 11, and
Further, the heat-generating electronic component (microcomputer) 17b is efficiently cooled via the heat absorbing portion 40 formed on the inner wall surface 11c of the case 11.

As described above, the cooling structure of the electronic component of the present embodiment has an ECU (electronic control unit) 10 having an electronic control circuit 15 inside a case 11 having a bag structure and a print forming the electronic control circuit 15 of the ECU 10. Among the electronic components 17a, 17b and 17c mounted on the substrate 16, a heat-generating electronic component (microcomputer) 17b mounted (surface mounted) along the surface of the printed circuit board 16 and a heat-generating electronic component 17b Heat absorbing portion 40 formed inside case 11 of ECU 10 so as to face and approach the surface of
And a protrusion 50 as a fixing portion formed inside the case 11 of the ECU 10 so as to fix the printed circuit board 16 while maintaining the positional relationship between the heat absorbing portion 40 and the surface of the electronic component 17b having heat generation properties. Things.

That is, the case 11 of the bag structure of the ECU 10
Printed circuit board 16 of electronic control circuit 15 housed inside
A heat absorbing portion 40 is formed on an inner wall surface 11c of the case 11 so as to face and be close to an electronic component (microcomputer) 17b having a heat-generating property, which is surface-mounted. Therefore, heat from the heat-generating electronic component (microcomputer) 17 b is efficiently cooled through the heat absorbing portion 40 formed on the inner wall surface 11 c of the case 11. At this time, the protrusion 50 formed on the inner wall surface 11c of the case 11
As a result, the front end of the printed circuit board 16 is fixed, and the positional relationship between the heat absorbing portion 40 and the surface of the heat-generating electronic component 17b is appropriately maintained, so that the reliability of the ECU 10 can be improved.

Further, the cooling structure of the electronic component of this embodiment is as follows.
The heat absorbing unit 40 and the protrusion 50 as a fixing unit
It is formed at the same time as the case 11 is formed. That is, the case 11 of the ECU 10 is formed by aluminum alloy die casting. However, since the heat absorbing portion 40 and the protruding portion 50 are formed at the same time, the structure is not complicated, and the number of parts is increased to increase the cost. Not even. The heat absorbing portion 40 formed simultaneously with the case 11
According to the projections 50, the heat-absorbing portion 40 achieves efficient cooling of the heat-generating electronic component (microcomputer) 17b, and accurate positioning of the projections 50 with respect to the printed circuit board 16 is achieved.

By the way, in the above embodiment, the shape of the heat absorbing portion 40 is a fin shape having irregularities. However, the present invention is not limited to this, and the inner wall surface 11c of the case 11 is not limited to this. The outer shape of the case 11 may be made thinner in a step-like manner by bringing it close to the shape of the electronic component (microcomputer) 17b having heat generation properties.

Further, in the above embodiment, the projection 50 is provided on the bottom surface side of the case 11 of the ECU 10. However, the present invention is not limited to this, and the vicinity of the slit grooves 13a, 13b is not limited thereto. May be provided on the inner wall surface 11c of the case 11. At this time, the protruding portion 50 is connected to the heat-generating electronic component 17 so that the printed circuit board 16 vibrates due to the vibration during traveling of the vehicle and the heat-generating electronic component (microcomputer) 17 b does not contact the heat absorbing fin 40.
It is preferable to provide it on the back side of the case 11 from the surface mounting position of b.

Then, when the present invention is carried out, the heat absorbing portion 4
0 may be a fin shape or a substantially rectangular parallelepiped. In particular, it is desirable to have a shape that increases the surface area on the inner surface side and the outer surface side. However, when dirt or the like adheres to the outer surface, Since cooling is possible by heat conduction, it is not always necessary to stick to increasing the area of the outer surface.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a storage state of an ECU and a storage box to which an electronic component cooling structure according to an embodiment of the present invention is applied.

FIG. 2 is an exploded perspective view showing a main configuration of an ECU according to an example of the embodiment of the present invention.

FIG. 3 is a sectional view showing a fixed state of an electronic control circuit in a case of the ECU of FIG. 2;

FIG. 4 is a sectional view showing the internal structure of a single case of the ECU in FIG. 3;

FIG. 5 is a top view showing the internal structure of the case unit of FIG. 4;

FIG. 6 is a partial detailed cross-sectional view taken along line AA of FIG.

[Explanation of symbols]

 Reference Signs List 10 ECU (Electronic control unit) 11 Case 15 Electronic control circuit 16 Printed circuit board 17a, 17b Heat-generating electronic component 40 Heat absorbing part 50 Projecting part (fixing part)

Claims (2)

[Claims] An electronic control unit having an electronic control circuit inside a case having a bag structure, and an electronic component mounted on a substrate forming the electronic control circuit of the electronic control unit, mounted along a surface of the substrate. An electronic component having a heat generating property, a heat absorbing portion formed inside the case of the electronic control unit opposed to and close to the surface of the electronic component having the heat generating property, A fixing part formed inside the case of the electronic control unit for holding the positional relationship with the surface of the electronic component and fixing the substrate. 2. The cooling structure for an electronic component according to claim 1, wherein said heat absorbing portion and said fixing portion are formed simultaneously with formation of said case of said electronic control unit.