JPH0539657Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat dissipation structure for an in-vehicle electronic device covered with a case such as a resin case.

[Prior Art] As a conventional heat dissipation structure of this type, there is a structure as shown in FIG. 6, for example. In the figure, reference numeral 1 denotes an on-vehicle electronic meter equipped with a fluorescent display tube 2 inside, and inside a resin case 3 of this electronic meter 1, there is a circuit board 4 to which the fluorescent display tube 2 is attached, and a circuit board 4 on which the fluorescent display tube 2 is attached. A circuit unit 5 connected to the lower surface of the circuit board 4 and a power transistor 6 for driving the fluorescent display tube 2 are provided, and a heat sink 7 in contact with the power transistor 6 is fixed to the circuit board 4 by mounting screws 8. ing. Reference numeral 9 indicates a cover that is attached to the opening of the resin case 3. Heat sink 7 of the power transistor 6
The resin case 3 has a shape that is housed in a resin case 3, and in order to air-cool the heat sink plate 7, a heat radiation through hole 10 is bored in the resin case 3.

[Problems to be Solved by the Invention] However, in the case of such an air cooling means for the heat sink 7, a relatively large amount of heat is applied to the resin case 3 in order to increase the contact between the heat sink 7 inside the resin case and the outside air. Although it is desirable to form the through hole 10, by increasing the diameter of the through hole 10, foreign matter can easily enter the case 3 through the through hole. Further, if the strength of the resin case 3 decreases, problems such as irritation may occur. If the diameter of the through hole 10 is made smaller in order to improve this problem, a problem arises in that the cooling effect of the heat sink 7 is reduced.

[Means for Solving the Problems] The present invention has been made by focusing on such conventional problems, and its first purpose is to solve the problem by The purpose of this is to pull out the other end of the heat sink to the outside of the case and expose it, increasing contact with the outside air and increasing the air cooling effect. The second purpose is to provide a protective wall close to the protrusion of the heat sink in order to prevent the protrusion of the heat sink from being damaged. Third
The purpose of this is to prevent dust from entering the case and reducing the strength of the case by making the diameter of the hole for drawing out the heat sink provided in the case relatively small.

[Example] The present invention will be explained in detail below based on the example shown in FIGS. 1 to 5. The same parts between the structure of this example and the structure explained in the conventional example The reference numerals used will be given and the explanation of the same structural parts will be omitted.

1 to 3, reference numeral 11 denotes a resin case for an in-vehicle electronic device, and this resin case 11
A through hole 12 is formed in the housing for allowing the heat dissipating plate 7, whose one end is in contact with the power transistor 6 and is fixed to the circuit board 7, to protrude to the outside of the case. It is desirable that the hole diameter L of the through hole 12 is approximately three times the thickness l of the heat sink plate 7. Reference numeral 13 denotes a protective wall provided in parallel with and close to the heat sink 7 protruding from the resin case 11, and this protective wall 13 is formed integrally with the resin case 11. Further, the height H of the protective wall 13 is set to be larger than the protrusion length h of the heat sink 7 that protrudes from the resin case 11. Furthermore, ventilation holes 14 are provided at appropriate locations in the protective wall 13 to enhance the air cooling effect of the heat sink plate 7. In this embodiment, the power transistor 6 is mounted so that the direction is parallel to the circuit board 4, but the power transistor 6 is mounted so that the direction is perpendicular to the circuit board 4. A mounting hole 15 is formed in the heat sink 7 to be used when mounting the heat sink 7 on the heat sink 7 .

In this way, in this embodiment, the resin case 1
Since the tip of the heat sink 7 that is in contact with the power transistor 6 inside the power transistor 1 protrudes to the outside of the resin case 11, the heat dissipation effect of the heat sink 7 is enhanced by the air cooling effect of the protrusion. . Further, a protective wall 13 is provided in the vicinity of the protrusion of the heat sink 7 that protrudes from the resin case 11 and is arranged in parallel with the protrusion. Since the heat dissipation plate 7 is set to be hidden on one side, the protruding portion of the heat dissipation plate 7 can be effectively protected externally, and damage to the heat dissipation plate 7 can be prevented. Also, a through hole 1 for causing the heat dissipation plate 7 to protrude outward from the inside of the resin case 11.
Since the diameter L of the hole 2 is set to about three times the thickness l of the heat sink 7, the diameter L of the hole is not so large and there is no problem that dust may enter into the resin case 11 through the through hole 12. It can be resolved. Also, through hole 1
By setting the hole diameter L of No. 2 to approximately 3L, it is also effective to allow the hot air that is convecting inside the resin case 11 to protrude outside through the through hole 12, thereby preventing hot air from being trapped inside the resin case 11. This prevents deformation of the resin case 11, and as shown in FIG. This has the advantage of improving assembly workability. Furthermore, by providing ventilation holes 14 in the protective wall 13, even if the protective wall 13 is close to the heat sink 7, the air cooling effect of the heat sink 7 can be enhanced.

FIG. 5 shows another embodiment of the present invention. In this embodiment, a relatively tall power supply circuit 16 such as a capacitor or transformer is housed inside the resin case 11. Inevitably, an upright wall 17 is formed to increase the depth of the resin case 11. Therefore, in the case of the resin case 11 having such a shape, the upright wall 17
By using the heat dissipation plate 7 as a protective wall in the embodiment described above, damage to the heat sink plate 7 can be effectively prevented.

[Effects of the invention] As described above, the present invention provides the case 11 with the through hole 12 for protruding the heat sink, and allows the heat sink 4 installed in the circuit board 4 housed in the case 11 to be inserted through the through hole 12. 7 protrudes outside the case, and a protective wall 13 or 17 is provided adjacent to the through hole 12 to protect the heat sink plate 7 from external forces. Since the tip of the heat sink 7 that is in contact with the power transistor 6 is projected outside the case 11, the heat dissipation effect of the heat sink 7 is enhanced by the air cooling effect of the protrusion. Further, since the protective wall 13 is provided in the vicinity of the protrusion of the heat sink 7 that protrudes from the case 11 and is arranged in parallel with the protrusion, the protrusion of the heat sink 7 can be effectively protected externally. You can get the same effect.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the heat dissipation structure according to the present invention, FIGS. 2 and 3 are enlarged front sectional views and side sectional views of the main parts thereof, and FIG. 4 is an explanatory diagram of its operation.
FIG. 5 is an explanatory diagram showing another embodiment of the present invention, and FIG. 6 is an explanatory diagram of a conventional example. 11...Resin case, 12...Through hole, 13...
Protection wall, 14... Through hole, 15... Mounting hole, 16...
...power supply circuit, 17...standing wall.

Claims (1)

[Scope of utility model registration request] A through hole 12 for protruding a heat sink is provided in the case 11, and the heat sink 7, which is erected on the circuit board 4 housed in the case 11, is provided to protrude from the through hole 12 to the outside of the case. A heat dissipation structure characterized in that a protective wall 13 or 17 is provided adjacent to the heat dissipation plate 12 to protect the heat dissipation plate 7 from external force.