JPH07312491A - Naturally cooled housing and convection heat control mechanism - Google Patents

Abstract

PURPOSE:To prevent a heat-sensitive device generating no heat from being heated by a heat generating device by disposing a convection suppressing means for increasing the resistance of the wall surface against the air flow to suppress the updraft above a high heat generation electronic device mounted on a printed board thereby restraining time convectional diffusion of heat. CONSTITUTION:A high heat generation electronic device 2, e.g. an LSI, mounted on a printed board 1 is housed in a housing 4 along with a device generating no heat, e.g. a battery 3. Convection suppressing frictional plates 6 for increasing the resistance of the wail surface against the air flow to restrain the updraft are combined into a grid and disposed above the high heat generation electronic device 2, e.g. an LSI, mounted on the printed board 1. When the convection suppressing frictional plates 6 are made of a thermal conductor, the plates themselves serve as a heat channel to enhance heat transfer onto the surface of the housing 4 and heat dissipation effect. Consequently, convectional diffusion of heat is restrained i,n the housing 4 and a heat-sensitive device generating no heat is protected against a heat generating device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to control convection in a casing in a naturally air-cooled casing and control heat generated inside the casing.

[0002]

2. Description of the Related Art In the conventional natural air-cooling system, a ventilation port for taking in outside air for cooling the inside of the housing and for discharging warm air in the housing is provided in the housing for heat treatment generated from electronic parts. With the provision, heat transfer by natural convection is promoted, and the high heat generating element is cooled by convection so that the temperature of the air inside the housing and the parts become uniform.

Next, the operation will be described with reference to the drawings. FIG. 12 is a cross-sectional view showing a mounting structure inside a conventional natural air-cooled housing (Conventional Example 1) for conceptually showing a heat transfer mechanism, and FIG. 13 is a perspective view of the housing. In the figure, 1 is a printed circuit board on which an electronic component such as LSI is mounted, 2 is a high-heat-generating electronic component such as LSI, 3 is a non-heat-generating component such as a battery, 4 is a housing, and 5 is heat generated from the electronic component 2 that generates heat. The flow of air warmed by
That is, the arrow indicates natural convection. Note that natural convection is caused by the thermal expansion of air near the heating element and the generation of buoyancy due to the difference in fluid density. Particularly, it is actively generated near the high heat-generating components on the printed circuit board 1 and causes the air inside to flow, It acts to equalize the temperature due to internal heat diffusion.

FIG. 14 is a view showing an example of an improvement of the above-mentioned conventional example, and is a cross-sectional view of a case (conventional example 2) in which a natural air-cooled case is provided with a ventilation port. FIG. 15 is a perspective view of this housing. In the figure, reference numeral 12 is a ventilation port newly provided in the conventional example. The cool air outside the housing is taken in through the ventilation port 12, and the air inside the housing 4 that has been warmed by the heat generated from the LSI, which is a high heat-generating component, exits from the ventilation port 12 to exchange heat between the inside air and the outside air. It is aimed at promotion.

[0005]

As described above, in the conventional internal structure of the natural air-cooled housing, the air temperature in the housing is made uniform, so that the heat-sensitive parts such as the battery, which are non-heat generating parts, are heated. As a result, there has been a problem that deterioration of parts that are susceptible to heat is promoted and the reliability of the electronic device is lowered.

The present invention has been made to solve the above problems, and when a high heat generating element such as an LSI and a non-heat generating and heat weak device such as a battery are mounted in the same housing, An object of the present invention is to provide a structure that prevents heat generation from a heat-generating component to a non-heat-generating component that is weak against heat by suppressing internal convective heat diffusion and effectively functions for heat control inside the housing.

[0007]

A natural air-cooled housing according to the present invention is a housing for accommodating a printed circuit board, wherein wall resistance when air flows over an electronic component mounted on the printed circuit board and having a high calorific value. And a convection suppressing means for suppressing the ascending airflow.

Further, the convection suppressing means is formed as a convection suppressing component separated from the housing.

Further, the convection suppressing means is formed of a good heat conductor.

Further, the convection suppressing means is constituted by a convection heat suppressing friction plate constituted by plates combined in a lattice shape.

Further, the convection suppressing means is constituted by a ventilation area control plate in which the plates combined in a lattice form are angled.

Further, the convection suppressing means is constituted by a convection suppressing friction plate with knurls in which uneven plates are provided on a plate combined in a grid pattern.

Further, the convection suppressing means is constituted by a convection outflow suppressing plate provided in a coronal shape substantially at right angles to the convection direction of the electronic component.

Furthermore, the convection heat control mechanism of the present invention is such that the electronic components mounted on the printed circuit board and having a high heat generation amount are surrounded by convection inflow shielding walls.

[0015]

In the natural air-cooled housing of the present invention, the convection suppression means provided on the upper part of the high heat-generating electronic component such as LSI, in the board on which the electronic component having a high heat generation amount is mounted, has a frictional resistance against the wall surface when air flows. , Which suppresses the upward airflow, suppresses the occurrence of convection and suppresses the diffusion of convective heat.

Further, the convection suppressing component provided separately from the housing increases the frictional resistance with the wall surface when the air flows and suppresses the upward air flow.

Further, since the convection suppressing means is formed of a good conductor of heat, the convection suppressing means itself serves as a heat passage, and the effect of transferring the heat generated from the electronic components to the upper part of the housing and the upper part of the housing to the outside of the housing. The heat radiation effect to

Further, a convection heat suppressing friction plate constituted by plates combined in a lattice shape suppresses convection.

Further, the ventilation area control plate in which the plates combined in a lattice shape are provided with an angle increases or decreases the width of the ventilation passage to increase the ventilation resistance.

Further, the convection-suppressing friction plate with knurls, in which the plates combined in a grid pattern are provided with uneven undulations, further increases the frictional resistance with the wall surface during air flow.

Further, the convection outflow suppressing plate provided in a coronal shape substantially at right angles to the convection direction of the electronic component suppresses an ascending airflow when natural convection occurs near the convection generating surface.

Further, in the convection heat control mechanism according to the present invention, the convection inflow shielding walls which surround the electronic component having a large heat generation amount in four directions block the inflow of air from the surroundings when natural convection occurs.

[0023]

【Example】

Example 1. Hereinafter, description will be given with reference to the drawings. Figure 1
FIG. 2 is a sectional view showing a mounting image of a natural air-cooled housing provided with a convection suppressing means which is an embodiment of the present invention, and FIG. 2 is a perspective view showing the mounting image. In FIG. 1, 1 is a printed circuit board on which electronic components are mounted, and 2 is a printed circuit board 1.
Highly heat-generating electronic components such as LSI mounted in the above, 3 is a battery which is a non-heat generating component, 4 is a housing, and each device 1 to 3 is mounted in the housing 4. Reference numeral 5 is an arrow indicating the flow of air generated from heat-generating electronic components, that is, natural convection, and 6 is a convection suppressing friction plate configured by combining plates as a convection control means for suppressing natural convection. The convection-suppressing friction plate 6 may be made of the same resin as that of the housing or a metal made of a material different from that of the housing. Further, when the material of the convection suppressing means is a good conductor of heat, the convection suppressing means itself functions as a heat passage, and the heat transfer to the upper surface of the housing and the heat radiation effect are increased.

In this embodiment, the plates are combined in a grid pattern on the printed circuit board to provide a large number of small chambers, but the plates may be installed in parallel.

Further, it is not necessary to provide it on the entire surface of the printed circuit board, and it may be installed only in a portion where convection is actively occurring, and the same effect can be expected.

Example 2. FIG. 3 is a view showing a cross section of a natural air-cooled housing provided with a convection suppressing means which is another embodiment of the present invention, and FIG. 4 is a perspective view showing a mounting image inside the housing. In the figure, the same or equivalent parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the convection suppressing friction plate 6 as the convection suppressing means of the first embodiment is manufactured as a convection suppressing friction component 7 which is a separate component as shown in FIG. Since it is attached to the housing 4 by adhesion or screwing, the convection suppressing friction component 7 can be easily manufactured and the same effect as that of the first embodiment can be obtained.

Example 3. FIG. 5 is a view showing a cross section of a natural air-cooled housing provided with a convection suppressing means which is another embodiment of the present invention. In the figure, the same or equivalent parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the convection suppression plates 6 of the first embodiment are not parallel to each other, but are angled as shown in FIG.
By using as a convection suppressing means, the ventilation passage cross-sectional area changes in the air flow direction to increase the ventilation resistance, thereby further improving the effect.

Example 4. FIG. 6 is a view showing a cross section of a natural air-cooled housing provided with a convection suppressing means which is another embodiment of the present invention. In the figure, the same or equivalent parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the convection suppressing friction plate 6 of the first embodiment is replaced by a knurled convection suppressing friction plate 9 having a rugged surface as shown in FIG. It was something that I was supposed to do. The length of the convection suppressing friction plate 9 with knurls may be different for each plate.

Example 5. FIG. 7 is a sectional view showing a mounting image of a further embodiment of the present invention, and FIG. 8 is a perspective view thereof. In the figure, the same or equivalent parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the figure, 10 is a convection inflow shielding wall which prevents the inflow of air by convection. In this embodiment, in a printed circuit board 1 on which an electronic component 10 having a high calorific value such as an LSI is mounted, convection inflow shielding walls 10 are provided around the electronic component 2 having a high calorific value, and air from the surroundings in natural convection is provided. The inflow is blocked so that the heat is prevented from diffusing to the heat-sensitive device, and the same effect as that of the above embodiment can be obtained.

Example 6. FIG. 9 is a sectional view showing a mounting image of a natural air-cooled housing provided with a convection suppressing means which is still another embodiment of the present invention, and FIG. 10 is a perspective view thereof. In the figure, the same or equivalent parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the figure, 11 is a convection outflow suppression plate as a convection suppression means. In this embodiment, in the printed circuit board 1 on which the electronic component 2 having high heat generation such as LSI is mounted, the electronic component 2
A plate (convection outflow suppression plate) maintained at an angle close to the convection direction at a short distance above the upper part of the convection is provided to suppress the ascending air current at the time of occurrence of natural convection in the vicinity of the convection generation surface. It is designed to be effective. It should be noted that the convection outflow suppression plate 11 is more effective in suppressing the fluid movement if it is not a simple flat plate as shown in FIG.

Example 7. FIG. 11 is a diagram showing still another embodiment of the present invention. In the figure, the same or equivalent parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the figure, 6a is a convection-suppressing friction plate 6 of the first embodiment made of a good heat conductor such as Al. Thus, by making the convection suppressing friction plate 6a a good heat conductor, the convection suppressing friction plate 6a itself serves as a heat passage, and the heat is transferred to the upper surface of the housing and radiated from the upper surface of the housing through the plate of the convection suppressing friction plate 6a. The effect is improved and the local high temperature is alleviated.

The above embodiments may be implemented in combination, and the effect is further enhanced.

In addition to the effect of controlling convection heat, the surface of the convection suppressing means is subjected to conductive plating, so that noise generated from electronic components and the like is shielded and the noise propagation to devices and the like in the vicinity is weakened. There is also.

Since the natural air-cooled housing according to the present invention is constructed as described above, it has the following effects.

The convection suppressing means provided on the upper part of the electronic component having a high calorific value increases the wall surface frictional resistance during the air flow to suppress the ascending air current, so that the convection of the heat generated from the electronic component is suppressed to suppress the heat generation. Since the diffusion is suppressed, it is possible to protect a heat-sensitive component such as a battery from being heated.
In addition to the effect of suppressing convection, the rigidity of the housing is increased, and the mechanical strength is increased.

Further, since the convection suppressing means is structured to be separated from the housing, the convection suppressing means can be easily manufactured.

Further, since the material of the convection suppressing means is a good conductor of heat, heat transfer and heat dissipation are improved.

Further, the convection suppressing friction plate formed in a lattice shape suppresses heat convection.

Further, since the ventilation area control plate changes the flow passage cross-sectional area in the air flow direction, the fluid flow (ventilation) resistance is increased and the convection suppression effect is further increased.

Further, since the surface of the convection-suppressing friction plate is provided with knurls having unevenness, the flow friction coefficient between the wall surface and the fluid surface increases, and the convection suppression effect increases.

Further, a convection outflow suppressing plate provided so as to be maintained at a distance near the upper part of the electronic component at an angle close to a right angle to the convection direction,
The upward airflow when natural convection occurs is suppressed near the convection generation surface, and the diffusion of convection heat is suppressed.

Further, the wall (convection inflow shielding plate) provided around the electronic components blocks the inflow of air from the surroundings in natural convection, and therefore the same effect can be obtained, and the battery heating due to the convection heat diffusion can be prevented. it can

Further, if the surface of the convection suppressing means is subjected to conductive plating, in addition to the heat control effect, it also has the effect of blocking noise generated from the LSI or the like and weakening the noise propagation to devices or the like in the vicinity thereof.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view of the first embodiment shown in FIG.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a perspective view of the second embodiment shown in FIG.

FIG. 5 is a sectional view showing Embodiment 3 of the present invention.

FIG. 6 is a sectional view showing Embodiment 4 of the present invention.

FIG. 7 is a sectional view showing Embodiment 5 of the present invention.

FIG. 8 is a perspective view of a fifth embodiment of the present invention.

FIG. 9 is a sectional view showing Embodiment 6 of the present invention.

FIG. 10 is a perspective view of Embodiment 6 of the present invention.

FIG. 11 is a sectional view showing Embodiment 7 of the present invention.

FIG. 12 is a cross-sectional view showing a mounting structure in a housing of Conventional Example 1.

FIG. 13 is a perspective view showing a mounting structure in a housing of Conventional Example 1.

FIG. 14 is a cross-sectional view showing a mounting structure in a housing of Conventional Example 2.

FIG. 15 is a perspective view showing a mounting structure in a housing of Conventional Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 printed circuit board 2 electronic component 3 battery 4 housing 5 convection 6 convection suppression friction plate 6a convection suppression friction plate 7 convection suppression component 8 ventilation area control plate 9 knurled convection suppression friction plate 10 convection inflow shielding wall 11 convection outflow suppression plate 12 ventilation mouth

Claims (8)

[Claims] 1. A housing for accommodating a printed circuit board,
A natural air-cooled housing, comprising convection suppressing means for increasing wall surface resistance during air flow to suppress an ascending air current above an electronic component having a high heating value mounted on the printed circuit board. 2. The natural air-cooled housing according to claim 1, wherein the convection suppressing means is formed separately from the housing. 3. The natural air-cooled housing according to claim 2, wherein the convection suppressing means is formed of a good heat conductor. 4. The natural air-cooled housing according to claim 1, wherein the convection suppressing means is a convection heat suppressing friction plate composed of plates combined in a lattice shape. 5. The natural air-cooled housing according to claim 1, wherein the convection suppressing means is formed by angling plates combined in a grid pattern. 6. The convection suppressing friction plate is a convection suppressing friction plate in which plates combined in a lattice shape are provided with uneven undulations. Natural air-cooled housing. 7. The natural environment according to claim 1, wherein the convection suppressing means is a convection outflow suppressing plate provided in a coronal shape substantially at right angles to a convection direction of the electronic component. Air-cooled housing. 8. Convection heat, comprising: a printed circuit board housed in a housing; and a convection inflow shielding wall surrounding four sides of an electronic component mounted on the printed circuit board and having a high heat generation amount. Control mechanism.