JP2717865B2 - Heat dissipation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention effectively radiates heat generated by a heat radiating device (heat sink), particularly active devices such as power transistors connected on a circuit board, which generate a large amount of heat. It relates to a so-called heat sink.

[Conventional technology and its problems]

2. Description of the Related Art As electronic device technology such as integrated circuits (ICs) advances, electronic devices become increasingly denser and faster, and as a result, generate a large amount of heat. Efficiently dissipating such heat to lower the temperature of the active device is essential for improving the reliability of electronic circuits. When electronic devices are miniaturized, the problem of heat generation becomes more apparent. In particular, when it is necessary to cover an electronic circuit, for example, in an engine control unit of an automobile or the like, it is an urgent problem how to solve a heat generation problem of various active devices used in the electronic circuit.

Conventionally, an active device is generally attached to a metal heat radiating plate made of aluminum or the like by means of screws or other means, and radiates heat naturally. However, when such a heat sink is also housed in a narrow cover, it does not function effectively because the ambient temperature in the cover increases. In such a case, it is conceivable to attach only the active device that generates heat to the outside and connect the active device to the main body with a lead wire or the like, but connecting to a physically distant position significantly reduces the operation speed. In addition to the problem, the method is not only reduced, but also faces problems such as noise, and cannot be applied to a detachable modular electronic circuit connected to the electric apparatus main body via a connector.

[Object of the invention]

Accordingly, it is an object of the present invention to provide a new auxiliary heat radiating device which is detachably attached to a main heat radiating plate to which an active device (heating element) is fixed, and improves a heat radiating effect of the main heat radiating plate.

It is another object of the present invention to provide a novel heat radiating device capable of easily and reliably radiating heat generated by an active device substantially surrounded by a cover.

[Summary of the Invention]

The heat-dissipating device of the present invention comprises a relatively large plate-like portion having a fork-like clamping portion which is clamped at an end of a main heat-radiating plate to which an active device mounted on a circuit board is fixed and which is mounted in a heat conductive relationship. It has a heat sink.

The main radiator plate is held vertically to the circuit board, and the auxiliary radiator plate is preferably held on the bottom surface of the circuit board via a fork-shaped holding portion. This auxiliary heat radiator forms a part of a cover surrounding the circuit board. The covered circuit board and the electronic circuit formed thereon are preferably modules connected to the electronic device body via an electrical connector. The auxiliary heat radiating plate which forms the bottom of the module is fixed to a heat radiating member such as a chassis of the electronic device body by, for example, screws.

When the circuit board to which the active device is connected is completely surrounded by an insulating cover or the like, an elongated opening is formed in the cover outer wall corresponding to the end of the main heat sink inside the cover, and through this opening. By inserting the holding portion of the auxiliary radiator plate into the main radiator plate and connecting them in a heat conductive relationship, the heat of the main radiator plate is conducted to the auxiliary radiator plate outside the cover to radiate heat.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings showing preferred embodiments of the present invention.

FIG. 1 is an exploded perspective view showing a preferred embodiment of a heat dissipation device according to the present invention. FIG. 1A shows the upper cover 10,
FIG. 1 (B) shows the electronic circuit main body, and FIG. 1 (C) shows the bottom cover and auxiliary heat radiating portion 24.

The main body is made of, for example, a rectangular aluminum thick plate, which is connected to the circuit board 12, an active device 14 which is a heating element such as a plurality of power transistors connected to the circuit board 12, and which is thermally connected to the active device 14. The main heat radiating plate 16 is included. Although not shown, a large number of active and passive circuit devices (components) other than these active devices 14 are connected to the circuit board 12 as a matter of course. In this embodiment, the main heat radiating plate 16 is mounted in a substantially vertical relationship with the circuit board 12. A fixed block 18 for interconnecting (interface) with an external circuit is fixed to the front (left) end of the circuit board 12 by a known means.
A power supply contact tab 20 and a large number of signal contacts 22 are arranged and fixed to the power supply contact tab. Although not shown, these contacts 20 and 22 are interconnected with external circuits by separate receptacle-type connectors. It should be noted that the active devices 14 are mounted with sufficient space at both ends of the main heat sink 16.

The upper cover 10 has a substantially rectangular parallelepiped shape having a low height with an open bottom surface and a front surface, and may be made of metal, plastic, or plastic covered with a metal coating. The main body in which the electronic components are assembled and wired is accurately positioned and stored in the upper cover 10 by a guide groove (not shown) or the like.

However, as described above, since the electronic unit is miniaturized by surrounding the main body with a low-profile upper cover, the volume of the cover 10 is limited, and even when the main heat sink 16 is used, the heat is sufficiently radiated. And the temperature inside the cover 10, especially the active device 14, becomes high. Therefore, in the present invention, as shown in FIG. 1 (C), under the circuit board 12, that is, the bottom surface (wall) of the cover 10.
A bottom plate / auxiliary heat radiating plate 24 which can use a tin-plated iron plate or an aluminum plate is used. This auxiliary heat sink 24
Has, for example, two fork-shaped elastic holding portions 26, and a slit 30 is formed in the holding portion 26 to form a fork shape.
The auxiliary heat sink 24 is elastically sandwiched between both ends of the main heat sink 16.
And a mechanical connection between the auxiliary radiator plate 24 and another portion, that is, the main body portion and the cover portion 10. Since this auxiliary heat radiating plate 24 has a sufficient surface area and is exposed to the outside, it is possible to effectively conduct the heat of the high-temperature main heat radiating plate 16 to the outside through the holding portion 26 and to radiate and cool the heat. . Furthermore, to effectively dissipate this electronic unit,
A device using this electronic unit, for example, an auxiliary heat radiating plate 24 of a vehicle body or the like is directly contacted and fixed. For that,
The auxiliary heat sink 24 has a mounting hole 28 such as a screw. In order to maximize the effect of the auxiliary heat sink 24, the thickness of the holding part 26 is made sufficiently thick to increase the contact area with the end of the main heat sink 16 and to increase the elasticity so as to hold with sufficient contact pressure. It is preferable to provide. Further, it is preferable that the width of the holding portion 26 is sufficiently large.

FIG. 2 is a perspective view showing an assembled state of the electronic unit shown in FIG. 1. A part of the cover 10 is shown in order to show a thermally and mechanically connected state of the main radiator plate 16 and the auxiliary radiator plate 24. Notched. In this embodiment, the slits 30 are formed in the holding portions 26 so as to hold both surfaces of each end of the main heat radiating plate 16, but when the main heat radiating plate 16 is relatively short and sufficiently thick. It is also possible to form the groove 30 without forming the slit 30 in each of the holding portions 26 or simply form a concave groove so that the end face of the main heat radiating plate 16 is brought into contact between the pair of holding portions 26 and held. Furthermore, if there is a gap in the middle portion of the main heat sink 16 in addition to the both ends, three or more holding portions 26 are formed, and a large number of holding portions of the auxiliary heat sink 24 are formed through openings in the circuit board. 26 may be coupled in a heat conductive relationship. In this case, the holding portion 26 is the auxiliary heat sink 24
It may be formed by punching a plate-shaped part of the above.

FIG. 3 is an exploded perspective view showing another embodiment of the heat dissipation device according to the present invention. FIG. 3 (B) shows an electronic unit main body, which is basically the same as the electronic unit of FIG. 1, except that substantially the entire surface is surrounded by a cover 10 'except for a connector at the front end. In particular, electronic control units for vehicles and the like require a completely enclosed configuration for waterproofness, drip-proofness, dustproofness, electromagnetic shielding, and the like. Cover in such a configuration
The temperature rise inside the 10 'further increases.

Therefore, in this embodiment, an elongated slot 32 is formed on a part of the cover 10 ', for example, an upper wall surface, in alignment with an end of a main heat sink (not shown) in the cover 10'. As shown in FIG. 3 (A), a pair of holding portions 36 of an auxiliary heat radiating plate 34 are inserted into the slots 32 to perform thermal coupling between the heat radiating plates 16 and 34. The dimensions of the auxiliary heat radiating plate 34 can be freely designed as required. However, since the auxiliary heat radiating plate 34 is exposed to the outside of the cover (or the case) 10 ', the heat of the main heat radiating plate 16 is effectively conducted and radiated to the outside. The temperature inside the cover 10 'is lowered to a safe allowable temperature.

When the auxiliary heat radiating plate 34 shown in FIG. 3 (A) is attached to the upper surface of the cover 10 'of the electronic unit shown in FIG. 3 (B), it projects outside the cover 10' by the thickness of the plate. Although such a slight protrusion is not a problem for most practical purposes, if this is a problem, the thickness of the upper wall surface of the cover 10 'is complementarily reduced in accordance with the shape of the auxiliary heat sink 34, It may be formed so as to have a substantially uniform upper surface.

The slot 32 of the cover 10 'is a holding portion of the auxiliary heat sink 34.
When 36 is inserted, it is substantially completely closed, so that waterproofness, dustproofness, etc. are sufficiently held for practical use. Also, the auxiliary heat sink
34 is not limited to the upper surface and may be disposed on both side surfaces, and may be disposed on the bottom surface as needed.

〔The invention's effect〕

As can be understood from the above description, according to the heat radiating device of the present invention, since the auxiliary heat radiating plate that is thermally coupled to the main heat radiating plate inside the cover (case) and is exposed to the outside is used, the electronic unit is compact and waterproof. Even if it is formed, it is possible to effectively reduce the internal temperature rise. In addition, the auxiliary radiator plate can be a part of the cover of the electronic unit.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an embodiment of an electronic unit using the heat radiator of the present invention, FIG. 2 is a partially cutaway perspective view showing an assembled state of FIG. 1, and FIG. 3 is a heat radiator of the present invention. FIG. 10 is an exploded perspective view showing another embodiment. 10, 10 '... cover, 12 ... circuit board 14 ... active device (heating element) 16 ... main radiator plate (member) 24, 34 ... auxiliary radiator plate (member) 26, 36 ... clamping part, 32 …… Aperture

Claims (3)

(57) [Claims] 1. At least one clamping portion clamped to an end of a main heat sink mounted substantially perpendicular to the circuit board in a heat conductive relationship with at least one active device connected to the circuit board; A heat radiating device comprising an auxiliary heat radiating portion formed integrally with the holding portion. 2. A radiator for at least one active device connected to a circuit board substantially enclosed within a cover, wherein the heat radiating device is mounted substantially vertically to the circuit board in a heat conductive relationship with the active device. A heat radiating device comprising: a heat radiating member; and a plate-shaped auxiliary heat radiating member having a holding portion detachably held at an end of the main heat radiating member, wherein the auxiliary heat radiating member is a part of the cover. . 3. A heat radiating device for at least one active device connected to a circuit board substantially enclosed in a cover, comprising: a thick plate-shaped main heat radiating member mounted in a heat conductive relationship with said active device. At least one opening formed at a position of the cover facing the main heat radiating member, and a holding portion disposed on the outer surface of the cover and attached to the main heat radiating member through the opening in a heat conductive relationship. A heat dissipating device comprising: an auxiliary heat dissipating member.