JP6843560B2 - Heat hole type heat dissipation mechanism - Google Patents

Description

The present invention relates to a heat dissipation mechanism for naturally air-cooling the inside of a box having a heating element inside.

In electronic devices in which a plurality of integrated circuits serving as heating elements are mounted inside a box, many of the electronic components including the integrated circuits generate a large amount of heat and require cooling in order to maintain their performance. In addition, not only other electronic devices but also boxes having a heating element inside often need to maintain the internal temperature below a predetermined temperature.

As a cooling method, there is a method of forcibly cooling by blowing cooling air directly to the heat generating part with an air cooling fan, but if there is no space for installing the air cooling fan or to ensure quietness, it is cooled by natural air cooling without using a fan. There is also a way to do it.

In the cooling method by natural air cooling, a method of increasing heat dissipation efficiency by attaching a heat sink (radiator) to a heating element such as an electronic component that generates heat is common. For example, as in Patent Document 1, a heat sink provided with fins for increasing the contact area with air is disclosed. In addition, there are many devices in which a water channel is further provided in the heat sink and the heating element is water-cooled via the heat sink.

Further, as a structure for radiating heat inside the sealed housing (box body) to the outside, a heat sink having hollow fins provided in the box body is penetrated as in Patent Document 2, and outside air is introduced to the hollow portion of the heat sink. A structure is also disclosed in which the heat inside the box is transferred to a heat sink so that the heat inside the box can be distributed and the heat inside is released mainly through the outer wall of the box.
As shown in Patent Document 2, it is very common to use both a heat sink and an air cooling fan in combination.

Jikkensho 55-126657 JP-A-2002-57479

Patent Document 1 and Patent Document 2 have a heat transfer cooling design that cools by transferring heat energy to the outer wall of the box body. However, since heat is transferred to the outer wall of the box, the outer wall becomes hot depending on the usage conditions, and there is a risk of burns when the user touches it.

In addition, as a method of securing the surface area of the box for the purpose of radiant heat, one is to provide a heat sink to expand the surface area of the exterior of the box according to the amount of heat generated, and the second is to consume the volume inside the box. It can be increased according to the power consumption. However, with these methods, if the product dimensions are limited, there is a high possibility that cooling will be insufficient.
Further, since the heat sink forms fins for increasing the contact area with air, it may lead to an increase in space and cost.

In view of the above-mentioned problems, in the natural air cooling of a box having a heating element inside, the present invention suppresses an increase in the temperature of the outer wall of the box due to the transfer of heat energy from the inside of the box to the outer wall, and the product dimensions are limited. It is an object of the present invention to provide a heat dissipation mechanism that sufficiently exhibits cooling performance by natural air cooling even in such a case.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 has a plurality of openings serving as an outside air intake port or a heat dissipation port on the outer wall of a box body having a heating element inside. A hollow heat hole having a hollow structure is provided so as to penetrate the inside of the box body, and in the heat hole, two types of heat plates having a U-shaped cross section with different web dimensions project from each other's flanges. The shape is such that the web of the first heat plate having the larger web size is brought into contact with the web of the second heat plate having the smaller web size so as to face each other in the direction, and the heat inside the box is formed. Is transferred to the air inside the hollow structure of the heat hole, air is convected due to the difference in temperature distribution inside the hollow structure of the heat hole, and the heated air is naturally radiated to the outside through the opening serving as a heat dissipation port. It is a heat hole type heat dissipation mechanism characterized by being used.

The invention according to claim 2 is the heat hole type heat dissipation mechanism according to claim 1, wherein the material of the heat hole is pure copper having a purity of 99.9% by mass or more.

The invention according to claim 3 is the heat hole type heat dissipation mechanism according to claim 1 or 2 , wherein the shape of the opening gradually expands toward the outer wall of the box body.

The invention according to claim 4 is characterized in that the cross-sectional area of the portion of the opening facing the outer wall of the box is 1.5 to 2 times that of the inside of the heat hole. The heat hole type heat dissipation mechanism according to any one of items 3 to 3.

The heat hole type according to any one of claims 1 to 4 , wherein the invention according to claim 5 has a cross-sectional area on the intake side of the opening larger than a cross-sectional area on the heat dissipation side. It is a heat dissipation mechanism.

The invention according to claim 6 is the heat hole type heat dissipation mechanism according to any one of claims 1 to 5 , wherein the heat hole is inclined at a predetermined angle.

The invention according to claim 7 is the heat hole type heat dissipation mechanism according to any one of claims 1 to 6 , wherein the inner wall of the heat hole is mirror-finished.

The invention according to claim 8 is the invention according to any one of claims 1 to 7 , wherein the openings of the heat holes are provided in pairs on the facing surfaces of the box body. It is a heat hole type heat dissipation mechanism.

The invention according to claim 9 is the invention according to any one of claims 1 to 8 , wherein the heat holes are provided so that the openings are vertically positioned when the box is placed. It is a heat hole type heat dissipation mechanism.

According to the invention of claim 1, since the heat sink type heat dissipation mechanism that enables highly efficient natural heat dissipation air cooling eliminates the need for a heat sink, the device can be miniaturized, and the high heat dissipation characteristics of the heathole type heat dissipation mechanism have been conventionally used. It is not necessary to rely on cooling by heat transfer to the outer wall of the box, which is the cooling method of the above, and the risk of injury can be eliminated. In addition, since the heat dissipation characteristics are high, a normally used fan is not required, and the manufacturing cost and running cost are very low. Further, it is very effective for heat dissipation of electronic devices, and can be used for various structures because it can be applied to other structures having a heating element inside the box body. Further, in the heat hole, two types of heat plates having a U-shaped cross section with different web dimensions face each other in the flange protrusion direction, and the web dimension of the first heat plate, which is the larger web dimension, is the web dimension. Since the shape is such that the flanges of the second heat plate, which is the smaller one, are brought into contact with each other and joined, the heat transfer performance of the first heat plate is improved. Since the performance is high, the heat hole can be configured more compactly.

According to the second aspect of the present invention, the heat dissipation characteristics can be further improved by using pure copper having a heat hole having a purity of 99.9% by mass or more.

According to the inventions of claims 3 to 5 , the efficiency of intake and heat dissipation can be improved without increasing the volume of the hollow structure portion inside the heat hole.

According to the sixth aspect of the present invention, since the heat hole is inclined at a predetermined angle, it is possible to facilitate convection of heat in the heat hole regardless of the mounting direction of the box body.

According to the invention of claim 7 , since the inner wall of the heat hole is mirror-finished, radiant heat reflection is generated inside the heat hole and heat convection is promoted to improve heat dissipation efficiency. be able to.

According to the invention of claim 8 , since the openings of the heat holes are provided in pairs on the facing surfaces of the box body, convection of intake air and heat dissipation can be smoothly performed.

According to the invention of claim 9 , since the heat holes are provided so that the openings are located vertically when the box is placed, the convection of intake and heat dissipation can be smoothly performed.

A schematic view of heat dissipation of the heat hole type heat dissipation mechanism according to the present invention is shown, (a) is a front view, and (b) is a partial cross-sectional view of the bottom surface. An embodiment of a heat hole type heat radiating mechanism according to the present invention is shown, (a) is a front view, (b) is a bottom view, (c) is a side view, and (d) is a perspective view. An embodiment of a first heat plate which is a component of a heat hole type heat dissipation mechanism according to the present invention is shown, (a) is a front view, (b) is a bottom view, (c) is a side view, and (d) is a side view. A perspective view is shown. An embodiment of a second heat plate which is a component of a heat hole type heat dissipation mechanism according to the present invention is shown, (a) is a front view, (b) is a bottom view, (c) is a side view, and (d) is a side view. A perspective view is shown. An embodiment in which the heat hole type heat dissipation mechanism according to the present invention is applied to an optical transmission device is shown, (a) is a front view, (b) is a bottom view, (c) is a plan view, and (d) is a left side view. , (E) show the right side view. The perspective view of FIG. 5 is shown. The schematic diagram of another embodiment of the heat hole type heat dissipation mechanism which concerns on this invention is shown. The schematic diagram of another embodiment of the heat hole type heat dissipation mechanism which concerns on this invention is shown. The temperature distribution by thermography at the time of the heat dissipation experiment by one embodiment of the heat hole type heat dissipation mechanism according to the present invention is shown, (a) shows the temperature distribution around the heat hole part, and (b) is the heat exhausted state from the heat hole part. The temperature distribution when a transparent film is attached to the back to observe is shown.

Hereinafter, an example of the embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic diagram of heat dissipation of the heat hole type heat dissipation mechanism according to the present invention, FIG. 2 shows an embodiment of the heat hole according to the present invention, and FIG. 3 shows components of the heat hole according to the present invention. 1 Embodiment of a heat plate is shown, FIG. 4 shows an embodiment of a second heat plate which is a component of a heat hole according to the present invention, and FIG. 5 shows an optical transmission of a heat hole type heat dissipation mechanism according to the present invention. An embodiment applied to the apparatus is shown, FIG. 6 shows a perspective view of FIG. 5, and FIG. 7 shows a schematic view of another embodiment of the heat hole type heat dissipation mechanism according to the present invention. An example of the case where the portions are installed so as to be in the horizontal direction is shown, and FIG. 8 shows a schematic view of another embodiment of the heat hole type heat dissipation mechanism according to the present invention. It shows two formed mechanisms. FIG. 9 shows the temperature distribution by thermography at the time of the experiment.

The heat hole type heat dissipation mechanism 10 is a mechanism for performing natural heat dissipation air cooling for internal cooling of a box body 30 such as an electronic device having a heating element 31 inside, and the heat hole 20 is a first heat plate 21 and a second heat plate. A hole 23 having a hollow structure is formed by 22 and penetrates the box body 30, and heat generated from the heating element 31 is transferred from the outer wall of the heat hole 20 to the air in the hole 23, and the intake opening 24 and the heat dissipation opening Heat is dissipated to the outside by natural heat convection by 25. In FIG. 1, it is mounted in the embodiment (a), and the lower part of the box body 30 is the intake opening 24 and the upper part is the heat dissipation opening 25.

As shown in FIGS. 2 to 4, the heat hole 20 has a structure in which two types of heat plates having a U-shaped cross section with different web dimensions are joined so as to face each other in the flange protruding direction. When the larger first heat plate 21 is the bottom view of FIG. 1 (b) or FIG. 2 (b), the flanges are arranged so as to project downward, and the second heat plate 22 having the smaller web size is a flange. Projects upward and the flange is joined so as to contact the lower surface of the web of the first heat plate 21 to form a hole 23 having a hollow structure. In the heat hole type heat radiating mechanism 10, air is convected inside the hollow structure of the heat hole, that is, due to the difference in the temperature distribution of the air transferred inside the hole 23, and the heated air rises from the opening serving as the heat radiating port to the outside. Because of the heat dissipation air cooling mechanism that utilizes the natural convection of heat that is naturally dissipated and the cold outside air is taken in from the opening that becomes the intake port, the opening provided on the lower side naturally becomes the intake port and is called the intake opening 24. The opening provided on the upper side serves as a heat dissipation port and is referred to as a heat dissipation opening 25.
In this embodiment, the first heat plate 21 and the second heat plate 22 are joined by screw using the screw holes 26 provided in the second heat plate 22. However, other joining methods such as welding using a laser or the like or bonding using a thermal conductive adhesive may be used.

When the heat holes 20 have the configurations shown in FIGS. 2 to 4, the flange shape of the first heat plate 21 can increase the strength of the heat holes 20 and further increase the heat transfer area, thus saving more space and achieving a heat dissipation effect. Can be enhanced. The shape of the heat hole 20 may be a commercially available hollow square bar, but the heat dissipation efficiency may be lower than that of the configuration shown in FIG.

If a material having high thermal conductivity such as copper or aluminum is used as the material used for the heat hole 20, heat dissipation is enhanced. In particular, the heat dissipation characteristics can be further improved by using pure copper with a purity of 99.9% by mass or more, which allows heat dissipation by natural convection even for a box with a calorific value that could not be cooled without using a fan in the past. It becomes possible to do.

Further, if the inner wall of the heat hole 20, that is, the wall surface on the side of the hole 23 is mirror-finished, radiant heat reflection is generated inside the heat hole and heat convection is promoted, so that heat dissipation efficiency can be improved. Mirror finishing is performed by methods such as buffing, plating, and alumite treatment.

The shape of the opening of the heat hole 20 may be the same as the internal cross-sectional shape of the hole 23 as shown in FIG. 2, and the openings 24 and 25 may be used as they are, but the cross-sectional area gradually expands toward the outer wall as shown in FIG. If the structure is such that the intake and heat dissipation efficiency is improved. In particular, if the intake opening 24 on the intake side is made larger than the heat dissipation opening 25, the natural heat dissipation air cooling effect including the chimney effect is enhanced.
If the cross-sectional area of the end of the opening is 1.5 to 2 times the cross-sectional area of the inside of the hole 23, the effect of natural heat dissipation air cooling can be easily obtained.

As shown in FIG. 1B, when the heat hole 20 is arranged so as to be sandwiched between the upper surface of the first heat plate 21 and the lower surface of the second heat plate 22 so that the heating element 31 is in close contact with the heat hole 20, the heat transfer efficiency is improved. It can be used effectively. In this embodiment, the heating elements 31 are arranged so as to be sandwiched between the circuit boards A32 and B33 of the optical transmission device having the structures of FIGS. 1, 5, and 6, and the heating element 31 is arranged downward on the substrate A32 to generate the first heat. The heating element 31 is arranged upward on the substrate B33 so as to be in close contact with the upper surface of the plate 21, and is arranged in close contact with the lower surface of the second heat plate 22. The heating element 31 is applicable not only to parts used in electronic devices such as integrated circuits but also to objects that require cooling. Further, the heating element 31 and the heat hole 20 may be brought into close contact with each other directly, or may be brought into close contact with each other via a heat transfer member 34 such as a heat transfer gel.

If the heat holes 20 have a pair of openings in the vertical direction as shown in FIGS. 1, 5, and 6, heat dissipation by natural heat convection can be smoothly performed, but the openings are formed as shown in FIG. There may be situations where it can only be installed in the horizontal direction. Therefore, by installing the intake opening 24 on the intake side as a fulcrum at an angle α upward as in the heat hole 20 of FIG. 7, it becomes possible to utilize natural heat convection due to the heat rise of the gas. The advantage of the heat hole type heat dissipation mechanism 10 of the present invention can be utilized. As described above, since the lower side of the opening naturally becomes the intake side, it is described that the intake opening 24 is inclined upward by an angle α with the intake opening 24 as a fulcrum for convenience, but it may be inclined.

Further, as shown in FIG. 8, it is also possible to use a heat hole type heat radiating mechanism 10 having three or more openings. As shown in FIG. 8, the intake opening 24 can be provided on the lower surface, but the heat dissipation opening 25 cannot be provided on the upper surface. For example, when another device is connected to the upper surface, the side surface other than the upper surface It is also possible to provide the heat dissipation opening 25. It is also possible to provide three or more openings depending on the amount of heat generated by the device. In FIG. 8, two heat dissipation openings 25 are provided, but not only that, but also a plurality of intake openings may be provided. It is also possible to provide an intake opening on the side surface.

A heat dissipation experiment was performed with the configuration of the box body 30 of FIGS. 1, 5 and 6, and the thermal resistance value and the allowable power value were measured and calculated by measuring the temperature. FIG. 9 shows the temperature distribution by thermography at the time of the experiment, FIG. 9 (a) shows the temperature distribution around the heat hole portion, and FIG. 9 (b) is transparent on the back surface for observing the heat exhaust state from the heat hole portion. This is the temperature distribution when the film is attached. A to D in FIG. 9 represent a remarkable part of the temperature change, and the temperature is A>B>C> D. The measurement points are inside the box, the outer wall of the box, and the surface of the integrated circuit. The temperature display in FIG. 9 is a reference value.
In the temperature distribution by thermography in FIG. 9 (a), the heat radiation opening 25 outlet portion A is the highest at about 40 ° C. The intake portion D of the intake opening 24 is about 30 ° C., and the temperature is A>B>C> D. As a result, the heat exhaust effect of the heat hole type heat dissipation mechanism 10 was confirmed. Also in FIG. 9B, it can be confirmed that the heated air rises from the heat dissipation opening 25.
The results of the thermal resistance values were 0.98 ° C./W inside the box, 0.90 ° C./W on the outer wall of the box, and 1.38 ° C./W on the surface of the integrated circuit.
The allowable power values were 20.4 W for the inside of the box, 22.2 W for the outer wall of the box, and 21.7 W for the surface of the integrated circuit.
As described above, the heat hole type heat dissipation mechanism 10 can secure the cooling performance inside the box and can suppress the temperature rise of the outer wall of the box, particularly the side surface.

In this embodiment, the configuration of the heat hole type heat dissipation mechanism has been described using an optical transmission device as an electronic device as a box body, but the present invention is not limited to this, and a box body having a heating element inside such as a handy camera, a storage device, or an experimental device is used. It can also be used as a cooling mechanism.

10 Heat hole type heat dissipation mechanism 20 Heat hole 21 1st heat plate 22 2nd heat plate 23 hole 24 Intake opening 25 Heat dissipation opening 26 Screw hole 30 Box body 31 Heating element 32 Board A
33 Board B
34 Heat transfer member

Claims (9)

A hollow heat hole having a plurality of openings serving as an outside air intake port or a heat dissipation port is provided on the outer wall of the box body having a heating element inside so as to penetrate the inside of the box body.
In the heat hole, two types of heat plates having a U-shaped cross section with different web dimensions face each other in the flange protrusion direction, and the web is formed on the web of the first heat plate having the larger web dimension. The shape is such that the flanges of the second heat plate, which has the smaller size, are brought into contact with each other and joined.
The heat inside the box is transferred to the air inside the hollow structure of the heat hole,
Air is convected due to the difference in temperature distribution inside the hollow structure of the heat hole.
A heat hole type heat radiating mechanism characterized in that heated air is naturally radiated to the outside through the opening serving as a heat radiating port and air-cooled. The heat hole type heat dissipation mechanism according to claim 1, wherein the material of the heat hole is pure copper having a purity of 99.9% by mass or more. The heat hole type heat dissipation mechanism according to claim 1 or 2 , wherein the shape of the opening gradually expands toward the outer wall of the box body. The heat according to any one of claims 1 to 3 , wherein the cross-sectional area of the portion of the opening facing the outer wall of the box is 1.5 to 2 times that of the inside of the heat hole. Hall type heat dissipation mechanism. The heat hole type heat radiating mechanism according to any one of claims 1 to 4 , wherein the cross-sectional area of the opening on the intake side is larger than the cross-sectional area of the heat radiating side. The heat hole type heat dissipation mechanism according to any one of claims 1 to 5 , wherein the heat hole is inclined at a predetermined angle. The heat hole type heat dissipation mechanism according to any one of claims 1 to 6 , wherein the inner wall of the heat hole has a mirror finish. The heat hole type heat radiating mechanism according to any one of claims 1 to 7 , wherein the openings of the heat holes are provided in pairs on opposite surfaces of the box body. The heat hole type heat dissipation mechanism according to any one of claims 1 to 8 , wherein the heat holes are provided so that the openings are vertically positioned when the box is placed.