JP2001244664A - Heat dissipation structure of electronic equipment installed outdoors - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the heat radiation efficiency of an electronic device installed aerial outdoors. SOLUTION: This is a heat radiation structure of an electronic device installed outdoors, in which an electronic component 6 that generates heat by operating is housed inside a casing 1 installed overhead in an outdoor manner, wherein a metal frame 7 on which the electronic component 6 is mounted is provided. A first mounting part which is disposed inside the casing 1 and has a part of an outer surface of the metal frame 1 serving as a heat radiating surface 12 and assembles the electronic component 6 by approaching or contacting the rear surface side of the heat radiating surface 12. The casing 1 is provided with an opening 5 for exposing the heat radiating surface 12 to the outside, and a heat sink 18 is joined to the heat radiating surface 12 exposed from the opening 5 so as to be able to conduct heat. ing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiation structure of an electronic device installed outdoors and overhead, such as an optical-electrical conversion / multiplexing device used in an optical network unit (Optical Network Unit).

[0002]

2. Description of the Related Art As is well known, electronic devices used for data communication and data processing are designed to have a higher degree of integration to reduce the size and at the same time to increase the capacity. For this reason, the heat generation amount of the entire electronic device is increased, and heat is easily trapped inside. On the other hand, electronic components used in such electronic devices tend to have relatively low heat resistance due to miniaturization of circuits and the like.
Therefore, a heat dissipation function of dissipating heat from the inside of the electronic device to the outside has become an important factor for increasing the capacity and improving the reliability of the electronic device.

Electronic equipment installed indoors such as a computer and operated by hand is practically always under control, so that a heat dissipation structure having a movable part such as an air-cooling fan is provided. Can be adopted. On the other hand, electronic devices that are installed aerial outdoors generally operate constantly and are difficult to be monitored by workers. No structure is required. In particular, since the air-cooling condition is established by being installed outdoors, it is desirable that the heat of the internal electronic components be transferred to the outer surface of the electronic device and dissipated to the outside.

One example is described in Japanese Patent Application Laid-Open No. 10-308586. The invention described in this publication relates to an optical-to-electrical conversion / multiplexing / demultiplexing device, in which a plurality of electronic components (subscriber channel units) housed inside a cabinet and a top plate of the cabinet are heated. A pipe is arranged, heat generated in the electronic components is transported to the top plate by a heat pipe, and the heat is radiated to the outside using the top plate as a heat dissipation surface. Therefore, in the heat dissipation structure described in this publication, since a part of the outer surface of the cabinet becomes a heat dissipation surface, the cabinet is made of aluminum die-casting in order to efficiently generate and conduct heat on the heat dissipation surface.

[0005]

In the above-described conventional heat dissipation structure, since the outer surface of the cabinet that directly contacts the outside air is formed as a heat dissipation surface, heat transfer to the outside air, that is, heat dissipation can be positively generated. However, for this purpose, the cabinet must be made of a metal having a high heat conductivity or heat transfer coefficient, and the weight of the entire electronic device increases accordingly. In particular, in an electronic device which is installed overhead, such as the above-described optical-electrical conversion / multiplexing separator, the installation workability is greatly impaired due to the large weight, and the mounting structure for the installation has a high strength. Need to do so, which can be a cost driver.

In the conventional heat radiation structure, since the heat is radiated from a part of the outer surface of the cabinet, the material of the cabinet is limited to the metal as described above, or the thermal characteristics are limited to those close to this. Therefore, weather resistance may be poor depending on the installation environment. Furthermore, if the integration degree is further increased and the whole is downsized, the cabinet itself also becomes smaller, so that the outer surface area, that is, the area of the heat radiating surface becomes smaller, and the heat radiating amount decreases in contrast to the increase in the heat generating amount. There is a disadvantage that the thermal characteristics deteriorate.

[0007] The present invention has been made in view of the above technical problem, and has as its object to improve the heat radiation characteristics of an electronic device installed outdoors.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, an electronic component which generates heat when operated is accommodated in a casing which is installed aerial outdoors. A heat dissipation structure for an outdoor electronic device, wherein a metal frame for mounting the electronic component is disposed inside the casing, and a part of an outer surface of the metal frame is a heat dissipation surface, and a back side of the heat dissipation surface. A first part for assembling the electronic component by approaching or making contact with
The casing is provided with an opening for exposing the heat radiating surface to the outside, and a heat sink is joined to the heat radiating surface exposed from the opening so that heat can be transferred. It is a characteristic heat dissipation structure.

Therefore, according to the first aspect of the present invention, the heat generated in the electronic component is transmitted to the heat radiating surface through the metal frame, through the air layer inside the casing, and further by heat radiation. Although this metal frame is installed inside the casing, its heat radiation surface is exposed to the outside through the opening, and a heat sink is attached to the exposed portion, so that the heat generated from the electronic components eventually becomes The heat is transmitted to the heat sink and is radiated to the outside. That is, the electronic components are naturally cooled.

According to a second aspect of the present invention, in the configuration of the first aspect, a second mounting portion for mounting an electronic component is provided on a side opposite to the back surface across the first mounting portion,
A heat pipe is provided between the second mounting portion and the heat radiating surface, wherein a heat pipe for transporting heat as latent heat of the working fluid sealed in the container is provided.

Therefore, according to the second aspect of the present invention, the heat generated from the electronic components in the second mounting portion that is not in contact with or joined to the heat radiating surface is radiated through the metal frame and the heat pipe and through the air layer. Transmitted to the surface.
Then, the heat is radiated from the heat sink to the outside air in the same manner as in the first aspect of the invention.

Further, according to a third aspect of the present invention, in the configuration of the first or second aspect, a surface of the heat sink facing the outer surface of the casing is formed larger than an opening area of the opening, and the heat sink and the casing are formed. And a sealing material surrounding the opening and maintaining liquid tightness.

Therefore, according to the third aspect of the present invention, even if an opening is formed in the casing, the opening is
It is sealed in a liquid-tight state by the heat sink and the sealing material. Therefore, even if the casing is installed outdoors and overhead, moisture does not enter the inside of the casing containing the electronic components, and the insulation is poor. An accident or failure due to a short circuit or short circuit can be prevented beforehand.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to a specific example shown in the drawings. FIG. 1 is a view schematically showing a specific example of the present invention. A casing 1 attached to support wires (not shown) stretched between telephone poles and installed overhead is made of a synthetic resin having weather resistance. For example, a horizontally long side surface is formed as a door 3 that can be opened and closed by a hinge 2. A packing (not shown) for maintaining watertightness is provided between the peripheral portion of the door 3 and the main body portion 4 to which the door 3 is attached. The door 3 is closed by a buckle (not shown). A rectangular opening 5 is formed in the upper surface of the casing 1 in the installed state.

The electronic components housed inside the casing 1 are, for example, line cards 6 for optical-electrical conversion. The line cards 6 are held inside the casing 1 by a metal frame 7. I have. That is, the metal frame 7 has three upper, middle, and lower metal plates 8, 9,
10 are arranged in parallel with each other at a predetermined interval and connected by a plurality of card rails 11 inserted between them. It is designed to be attached to.

The upper plate 8 constituting the metal frame 7
The upper surface (the upper surface in the installed state and the state shown in the drawing) 12 of the casing 1 is brought into close contact with the inner surface of the upper surface of the casing 1 in which the opening 5 is formed.
A plurality of ridges 13 are formed in a range corresponding to the opening 5 of the casing 1 among the two. The portion where the ridge 13 is formed is exposed to the outside from the opening 5,
In addition, the ridge 13 slightly projects above the casing 1. That is, the portion where the ridge 13 is formed is the heat radiation surface 12.

The back surface of the upper plate 8, ie, the ridge 13
Fins 14 for increasing the heat transfer area are integrally formed on the surface opposite to the surface on which is formed. Therefore, the heat generated from the line card 6 held between the upper plate 8 and the middle plate 9 by the card rail 11 is transferred to the upper plate 8, that is, the heat radiation surface 12 by heat transfer or heat radiation through the card rail 11 or the air layer. To be transmitted. The portion between the upper plate 8 and the middle plate 9 is a first mounting portion in the present invention.

Fins 15 for increasing the heat transfer area are integrally formed on the lower surface of the intermediate plate 9, that is, on the surface opposite to the first mounting portion, similarly to the upper plate 8. The line card 6 is inserted between a plurality of card rails 11 arranged between the middle plate 9 and the lower plate 10. Therefore, a portion between the middle plate 9 and the lower plate 10 is a second mounting portion in the present invention.

A heat pipe 16 is arranged between the middle plate 9 and the upper plate 8 forming a heat radiating surface. The heat pipe 10 is a heat conducting (heat transporting) member in which a thin pipe whose both ends are crushed flat is used as a container, and a condensable fluid such as water is sealed therein as a working fluid in a degassed state. , Configured to transport heat in the form of the latent heat of the working fluid. The heat pipe 16
Is arranged and fixed on the upper surface (the surface on the first mounting portion side) of the middle plate 9 along the longitudinal direction thereof. As an example, a groove is formed along the longitudinal direction on the upper surface of the intermediate plate 9, and one end of the heat pipe 16 is fitted into the groove and fixed.

Further, an intermediate portion of the heat pipe 16 protrudes from one end of the intermediate plate 9 in the longitudinal direction, the portion is bent upward by 180 degrees, and the other end of the heat pipe 16 is It is arranged along the upper surface (heat radiating surface) of the upper plate 8 and is fixed. As an example, the upper plate 8
A groove is formed on the upper surface of the heat pipe 16 along the longitudinal direction, and the other end of the heat pipe 16 is fitted into the groove and fixed.

Accordingly, heat generated from the line card 6 of the second mounting portion provided on the opposite side of the first mounting portion from the heat radiating surface may be used for heat transfer via the card rail 11 or the air layer, or The heat is transmitted to the middle plate 9 by heat radiation, and the heat is transferred to the heat dissipation surface 12 by the heat pipe 16 from here. In addition, one end of the second heat pipe 17 is disposed along the lower surface of the lower plate 10, and the other end of the second heat pipe 17 is bent upward in an L-shape to form the metal frame 7. It is along the side.

The above-described metal frame 7 is inserted into the casing 1 and fixed to the upper surface thereof. In this state, the upper surface 12 of the metal frame 7 is exposed from the opening 5 to the outside.
In addition, the ridge 13 slightly protrudes. On the other hand, a heat sink 18 is arranged on the upper side of the casing 1 and is joined to the upper surface 12 of the metal frame 7 as a heat radiating surface so that heat can be transmitted. The heat sink 18 is made of a material having good heat conduction and heat transfer such as aluminum die casting, and has a large number of fins 19 integrally formed on the upper surface. On the lower surface, a ridge 20 having a shape corresponding to the ridge 13 is formed. And this heat sink 1
8 is a ridge 20 on the lower surface of the metal frame 7
Meshing with the ridge 13 formed on the
The protrusions 20 are fitted between the metal frames 7, and are integrated with the metal frame 7 by fixing means such as screws.

The lower surface of the heat sink 18, that is, the surface facing the outer surface of the casing 1 has an area larger than the opening area of the opening 5, so that the lower surface of the heat sink 18 is And the surrounding area. An annular sealing member 21 surrounding the opening 5 is sandwiched between the lower surface of the heat sink 18 and the upper surface of the casing 1, and as a result, the opening 5 is sealed in a liquid-tight state, and from the outside. Water has been blocked.

Next, the operation of the heat radiating structure according to the present invention having the above structure will be described. The casing 1 containing the metal frame 7 and the line card 6 attached thereto accommodates other devices (not shown) such as a power supply device and a battery, and is exposed from the opening 5 on the upper surface. A heat sink 18 is joined to the upper surface (heat radiating surface) of 7 so that heat can be transferred. The electronic device (for example, an optical-electrical conversion / multiplexing separator) configured in this way is attached to a support line between utility poles and installed aerial outdoors. In this case, it is necessary to lift and hang the casing 1 containing the electronic components. However, the casing 1 does not need to have a heat radiation function itself, and therefore is made of a lightweight material such as a synthetic resin. As a result, the installation work becomes easy and the support structure can be simplified. Further, since there is no thermal restriction on the casing 1, not only the degree of freedom in selecting materials is improved, but also the degree of freedom in selecting shapes and colors is increased. Although it is exposed to the wind and rain by being installed aerial outdoors, since the opening 5 of the casing 1 is sealed in a liquid-tight state by a sealing material 21 sandwiched between the casing 1 and the heat sink 18, the line card 6 and the like are provided. It is possible to prevent a situation such as infiltration of electronic components inside the device.

The line card 6 mounted on the first mounting portion between the upper plate 8 and the middle plate 9 of the metal frame 7 and the second mounting portion between the middle plate 9 and the lower plate 10 are provided. The assembled line card 6 generates heat by being energized and operating. Since the line card 6 assembled to the first mounting portion is close to or in contact with the upper surface 12 which is a heat radiation surface, heat generated from the line card 6 of the first mounting portion is directly transmitted to the heat radiation surface 12. Or transmitted to the heat dissipation surface via the card rail 11 or the air layer,
Furthermore, it is transmitted by thermal radiation. In this case, since the fins 14 are formed on the lower surface of the upper plate 8 constituting the metal frame 7 and the fins 14 have an increased surface area, heat transfer through the air layer is performed efficiently.

The heat of the heat radiating surface 12 is transmitted from this to the heat sink 18, and the heat is radiated from the heat sink 18 to the outside air. In this case, the heat radiating surface 12 and the heat sink 18 are joined by engaging the respective ridges 13 and 20 with each other, and the contact area between them is large. Thermal resistance is small and heat is efficiently transferred. Also,
Since the protrusions 13 and 20 are formed, the thickness of the portion is large and the heat capacity is large. Therefore, even when the heat generation density of the line card 6 is high, the heat resistance of the heat radiation surface and the heat sink 18 is low. It is small and can efficiently dissipate heat at that point. Further, heat radiation to the outside air is generated by the heat sink 18 and its heat radiation area is
Alternatively, since the shape or structure of the metal frame 7 is not restricted, the heat radiation capacity can be increased as required.

The line card 6 attached to the second mounting section also generates heat when energized and operates.
Since the first mounting portion and the middle plate 9 are interposed between the line card 6 and the heat radiating surface, the heat generated from the line card 6 is directly transmitted to the heat radiating surface, that is, the upper plate 8 of the metal frame 7. Never. The heat generated from the line card 6 in the second mounting portion is transmitted to the intermediate plate 9 via the card rail 11, and further transmitted to the intermediate plate 9 via the air layer and further by heat radiation. In this case, since a large number of fins 15 are formed on the lower surface of the middle plate 9 (the surface on the side of the line card 6), heat transfer via the air layer is favorably performed.

Since the temperature is increased by transferring the heat to the middle plate 9 in this manner, a temperature difference occurs in the heat pipe 16 disposed between the middle plate 9 and the heat radiation surface. That is, since the temperature on the middle plate 9 side of the heat pipe 16 increases,
This serves as an evaporator, and the working fluid evaporates. On the other hand, the temperature at the end of the heat pipe 16 on the heat radiating surface side is relatively low, so that the working fluid vapor flows to the end on the heat radiating surface side due to the pressure difference, and then radiates and condenses. . Therefore, the end on the side of the heat radiating surface is a condensing portion. By operating the heat pipe 16 in this manner, heat is transported from the middle plate 9 side (that is, the second mounting portion) to the heat radiation surface (that is, the upper surface 12 of the metal frame 7) as latent heat of the working fluid of the heat pipe 16. Is done. Since the heat transfer amount, that is, the apparent thermal conductivity is, for example, several tens to one hundred and several tens times that of copper, the heat transfer amount from the second mounting portion to the heat radiation surface is
This is comparable to the amount of heat transfer from the first mounting portion to the heat radiation surface. That is, even if the second mounting portion is located away from the heat radiating surface and close to the center of the casing 1 (so-called deep position), the heat of the line card 6 in this portion is transferred to the heat radiating surface in a necessary and sufficient manner. It is possible to prevent or suppress a rise in the temperature of the mounting portion or the line card 6 attached thereto. In other words, since the heat-generating electronic components can be arranged in a deep portion of the casing 1 without causing a thermal problem, the size of the electronic device housing the casing 1 or the heat-generating electronic components can be reduced.

In the above specific example, the light-to-electricity conversion
Although the demultiplexer has been described as an example, the electronic device of the present invention is not limited to the above-described specific example, and may be any device that is installed outdoors and has an electronic component that generates heat inside. I just need. In addition, the casing of the electronic device to which the present invention is applied does not need to be a rectangular parallelepiped as described above, and may have an appropriate shape. Furthermore, the shape of the opening of the casing, the shape of the heat sink, or the material thereof in the present invention is not limited to those described in the above specific examples, and may be any appropriate shape and material as needed.

[0030]

As described above, according to the first aspect of the present invention, the heat generated by the electronic component is radiated through the metal frame or through the air layer inside the casing, and further by the heat radiation. Although the metal frame is installed inside the casing, the heat dissipation surface is exposed to the outside through the opening, and a heat sink is attached to the exposed part, so that heat is transmitted to the outside from here. The heat is dissipated, and eventually, the heat generated from the electronic component is transmitted to the heat sink, and is dissipated from the heat sink to the outside, so that the electronic component can be efficiently cooled by natural air. In addition, the casing does not perform the heat dissipation function, and the heat sink attached to the heat dissipation surface exposed to the outside of the casing directly dissipates heat, so a wide heat dissipation surface can be secured even if the casing is downsized. Therefore, according to the first aspect of the invention, it is possible to reduce the size of the casing and the overall configuration without lowering the heat radiation capacity. Furthermore, since the casing is not required to have a thermal function, the degree of freedom in selecting the shape, material, color, and the like is increased, and other functions such as weather resistance and bird and beast driving performance can be imparted or increased.

According to the second aspect of the present invention, the heat generated from the electronic component in the second mounting portion that is not in contact with or joined to the heat radiation surface is transmitted through the metal frame and the heat pipe and through the air layer. Since the heat is transmitted to the heat radiating surface through the heat radiating surface, it is possible to efficiently cool the electronic components located at a position distant from the heat radiating surface. The storage efficiency is improved, and the overall size and weight of the electronic device can be reduced.

According to the third aspect of the present invention, even if an opening is formed in the casing, the opening is sealed in a liquid-tight state by the heat sink and the sealing material. Even if it is installed outdoors and overhead, moisture does not enter the inside of the casing housing the electronic components, and accidents and breakdowns due to poor insulation or short circuits can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic exploded perspective view showing an example of the present invention.

[Explanation of symbols]

1 ... casing, 5 ... opening, 6 ... line card,
7 ... metal frame, 12 ... upper surface (radiation surface), 16 ...
Heat pipe 18 Heat sink 21 Sealing material

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masataka Mochizuki 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Yuji Saito 1-5-1, Kiba, Koto-ku, Tokyo Stock Company (72) Inventor Hirofumi Inoue 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (72) Inventor Tosumi Suenaga 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation Within the company (72) Inventor Shiro Soma 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (72) Inventor Hironobu Goto 7-1-1, Shiba 5-chome, Minato-ku, Tokyo NEC Corporation (72) Inventor Hitoya Nakamura 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (72) Inventor Makoto Ito 5-7-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation F-term (reference) 4E360 AB02 AB13 AB33 AB54 AB64 BB12 BB16 BC05 BD03 EA05 EB02 GA24 GA29 GB94 5E322 AA01 AA03 AB11 DB10

Claims (3)

[Claims] 1. A heat radiation structure for an electronic device installed outdoors in which an electronic component that generates heat by operating is housed inside a casing that is installed aerial outdoors. A metal frame for mounting the electronic component is provided inside the casing. And a first mounting portion for assembling the electronic component by approaching or contacting the rear surface side of the heat radiating surface is provided, and a part of the outer surface of the metal frame is a heat radiating surface. An opening for exposing the heat radiating surface to the outside is formed, and a heat sink is joined to the heat radiating surface exposed from the opening so as to be able to transfer heat. 2. A second mounting portion for mounting an electronic component is provided on a side opposite to the back surface across the first mounting portion, and a second mounting portion is provided between the second mounting portion and the heat radiating surface. 2. A heat pipe for transferring heat as latent heat of the working fluid sealed in the container.
The heat radiation structure of the electronic equipment installed outdoors described in. 3. A surface of the heat sink facing the outer surface of the casing is formed to be larger than an opening area of the opening, and surrounds the opening between the heat sink and the casing to maintain liquid tightness. The heat dissipating structure for an outdoor electronic device according to claim 1, wherein a sealing material is sandwiched.