JPH09329394A - Cooling structure of electronic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the cooling structure of an electronic element which is compact in size and high in cooling capacity. SOLUTION: A heat-generating electronic element 7 is set up inside a casing 5 under the cooling structure of this electronic element. In the case when a heat sink 17 to the electronic element 7 is set up so that it may be exposed to the outside from the casing 5, a first connector 11 is provided on the electronic element 7 so that it may receive the heat while a second connector 13 is provided on the heat sink 17 so that it may receive the heat. One end of a connection heat pipe 12 which is small-sized and flexible, is held with the first connector 11 so as to receive the heat while the other end of the connection heat pipe 12 is held with the second connector 13 so as to receive the heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for an electronic element, which uses a heat pipe for transporting heat as a latent heat of a working fluid to prevent overheating of the electronic element.

[0002]

2. Description of the Related Art In the field of computers, the output of electronic elements such as arithmetic processing units has been increasing with the increase in functions and processing speed. On the other hand, there is a strong demand for smaller and lighter computers, and of course,
The space that can be occupied by a device for cooling an arithmetic processing unit or the like in the internal space of the case is also extremely limited. Therefore, conventionally, a heat pipe having an excellent heat transport ability has been used as an example of a cooling device.

FIG. 4 is a computer for personal use (hereinafter referred to as a personal computer) described in the book "Practical Heat Pipe" (issued by Nikkan Kogyo Shimbun) distributed in Japan on October 25, 1960. An example of the heat pipe for use is shown. This heat pipe 1 is a so-called flat heat pipe, and the container is formed in a rectangular cross section.
The lower surface in the drawing of the container is a heating unit 1a, and the upper surface is a heat radiation unit 1b. A large number of heat radiation fins 1c are provided outside the heat radiation part 1b. Then, a predetermined amount of condensable working fluid 3 such as water is sealed inside the container after being sucked to a vacuum.

On the other hand, a central processing unit (hereinafter referred to as CPU) 2 is attached to a predetermined portion of a circuit formed on the printed circuit board 4, and the heat pipe 1 is attached to the upper surface of the CPU 2. Is attached with the heating portion 1a in close contact.

In the heat pipe 1, when the CPU 2 generates heat when the circuit is energized and the heating unit 1a is heated by the heat, the enclosed working fluid 3 is heated and boiled to generate steam. Then, the vapor of the working fluid 3 moves upward and condenses in the low-temperature radiator 1b. That is, the heat carried in the latent heat of vaporization of the working fluid 3 is dissipated from the heat radiation fins 1c provided outside the heat radiation portion 1b.

Therefore, the heat radiation fins 1c can be efficiently radiated by exposing the heat radiation fins 1c to the flow path of the cooling air by the cooling fan (not shown) in the housing of the personal computer. As described above, by using the heat pipe 1 for cooling the CPU 2, a large amount of heat can be transported in the state of latent heat of evaporation, so that the CPU 2 can be effectively cooled. As a result, it is possible to prevent the personal computer from becoming inoperable or deteriorating in function due to overheating of the CPU 2.

[0007]

According to the above-mentioned conventional heat pipe 1, in addition to its extremely high thermal conductivity, it comes into direct contact with the CPU 2, which is a heat source, over a wide area. The cooling efficiency of the CPU 2 can be improved. However, since the container is a hollow body having a rectangular cross section, the area of contact with the CPU 2 can be increased, but the area of the heat radiation portion 1b is relatively small.

That is, since the working fluid 3 is a liquid in the heating portion 1a, it suffices if the heating portion 1a has an area substantially equal to the upper surface of the CPU 2. However, since the working fluid 3 is vapor in the heat radiating portion 1b and the volume thereof is extremely increased, the vapor of the working fluid 3 is used in the conventional heat pipe 1 in which the heat radiating portion 1b has the same area as the heating portion 1a. The area of the heat radiating portion 1b in direct contact with each other is relatively small, and as a result, the amount of heat radiated is small and the substantial cooling capacity is limited.

Therefore, if the area of the heat radiating portion 1b is set to be large, the area of the heating portion 1a is inevitably enlarged and the heat pipe 1 itself becomes large in size, so that there is almost no extra space and the degree of freedom in arranging parts is low. It is not suitable for installation in the restricted PC case. As described above, a cooling device having a compact structure and a high cooling capacity has not been developed so far.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a cooling structure for an electronic element, which has a compact overall structure and a high cooling ability for the electronic element.

[0011]

In order to achieve the above-mentioned object, the invention of claim 1 is such that an electronic element which generates heat is installed inside a housing, and a heat sink for the electronic element is provided. In a cooling structure for an electronic element installed so as to be exposed to the outside from a housing, a first connector is provided to the electronic element so that heat can be transferred, and a second connector can be transferred to the heat sink. One end of the connecting heat pipe that is arranged and has a small diameter and flexibility is held by the first connector so that heat can be transferred, and the other end of the connecting heat pipe is the second connector. It is characterized by being held so that heat can be transferred.

Therefore, according to the invention described in claim 1, when the electronic element generates heat, the heat is transmitted to the first connector and further transmitted to one end of the connecting heat pipe. Then, the working fluid in the liquid phase is heated and evaporated, and the working fluid vapor flows toward the end portion of the container of the connecting heat pipe, which is disposed in the second connector with low internal pressure, and the second connector Is deprived of heat and condensed. The heat is conducted through the second connector, transferred to the heat sink, and released therefrom. As described above, since the heat sink is exposed to the outside of the housing, heat is not collected in the internal space of the housing, and the electronic element is cooled well.

Since the connecting heat pipe for connecting the first connector and the second connector inside the housing is flexible and has a small diameter, It can be arranged so as to pass through a gap between the provided parts, a so-called dead space.

Further, in the invention described in claim 2, in addition to the structure described in claim 1, the mounting groove for fitting the end portion of the connecting heat pipe in a state of closely adhering to each other,
It is characterized in that it is formed on each of the first connector and the second connector.

Therefore, according to the second aspect of the invention, since the container of the connecting heat pipe has a large area in direct contact with the first connector and the second connector, the heat transfer between the two can be performed well. Also, by moving the coupling heat pipe in the radial direction and fitting it in the mounting groove,
Since it can be removed, the connecting / disconnecting heat pipe can be easily attached / detached to / from the first connector and the second connector.

Further, in addition to the constitution described in claim 1 or 2, the invention described in claim 3 is such that a flat heating part and a heating part which are spaced apart from each other so as to face the heating part. Vacuum degassing inside a container formed in a hollow flat shape by a heat dissipation part having a large area and side wall parts connecting the peripheral parts of the heating part and the heat dissipation part to each other over the entire circumference. The first connector and the second connector are respectively constituted by a heat pipe in which a condensable fluid is sealed as a working fluid, and the electronic element is arranged in the heating portion of the first connector, and the heat dissipation of the first connector is further improved. End portions of the coupling heat pipes are respectively arranged in the heating section and the heating section of the second connector, and the heat sink is arranged in the heat radiation section of the second connector. It is intended.

Therefore, according to the third aspect of the present invention, when the electronic element generates heat, the heat is transmitted to the heating portion of the first connector having the heat pipe structure, thereby starting the heat pipe operation. It That is, the liquid-phase working fluid evaporates on the inner surface of the heating portion of the container, the working fluid vapor flows toward the heat radiating portion, and the heat is deprived and condensed on the inner surface of the heat radiating portion. The heat is transmitted from the heat dissipation portion to the connecting heat pipe.

In this case, since the first connector has the above-mentioned hollow flat shape, a large amount of working fluid vapor comes into contact with the heat radiating portion and the condensed working fluid is transmitted through the inclined side wall portion. Reflux to the heating part so that it concentrates from almost all directions. Therefore, the evaporation / condensation cycle of the working fluid is actively performed. That is, most of the heat applied to the first connector is transported by the working fluid, so that the thermal resistance between the electronic element and the coupling heat pipe is reduced as compared with the configurations according to the first and second aspects.

On the other hand, the heat transferred to one end of the connecting heat pipe is transferred to the other end by the working fluid enclosed in the heat pipe container, and then transferred to the heating part of the second connector. It Then, the heat pipe operation of the second connector is started. Even in that case, since a large amount of working fluid vapor is condensed on the inner surface of the heat radiating portion and the condensed working fluid is returned to the heating portion from almost all directions, heat transfer is actively performed. Therefore, the thermal resistance between the coupling heat pipe and the heat sink is reduced as compared with the configurations according to claims 1 and 2, and as a result, the cooling capability for the electronic device is further improved.

Further, since the first connector and the second connector are formed in a hollow flat shape in which the heat radiating portion is wider than the heating portion, for example, a general flat heat heat radiating portion and the heating portion have the same area. Occupies less space than pipes.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to specific examples. The example shown here is an example applied to cooling a CPU mounted on a personal computer (hereinafter referred to as a personal computer). The personal computer case 5, which corresponds to the housing of the present invention, is a hollow container formed of a plastic panel or a metal panel such as a magnesium alloy, and a printed circuit board 6 is provided substantially horizontally in the vicinity of the bottom inside thereof. . A CPU 7 corresponding to the electronic element of the present invention is attached to the upper surface of the printed circuit board 6 in FIG.

A heat collecting heat pipe 8 is attached to the upper surface of the CPU 7. This heat collecting heat pipe 8
Has a shape like a truncated pyramid with a low height container. More specifically, the heat collecting heat pipe 8 has a heating portion 8a having a square and flat surface and a heating portion 8a having a square area about four times as large as that of the heating portion 8a.
made of copper, which is composed of a heat radiating portion 8b which is spaced apart from the upper side of a and faces in parallel, and an inclined side wall portion 8c which connects the four sides of the heat radiating portion 8b and the respective four sides of the corresponding heating portion 8a. A closed container is used as a container, and a predetermined amount of pure water (not shown) is enclosed as a working fluid in a vacuum deaerated state inside the container.

The size and shape of the heating section 8a are
The shape and size are substantially the same as the top surface of the CPU 7. And this heat collecting heat pipe 8 and CP
U7 is fixed by an appropriate means (not shown) in a state where the heating portion 8a is in close contact with the upper surface of the CPU 7. Therefore, the CPU 7 and the heat collecting heat pipe 8 can transfer heat to each other.

On the upper surface of the heat radiating portion 8b of the heat collecting heat pipe 8, there is a heat transfer plate 9 made of copper or aluminum alloy.
Is attached. The heat transfer plate 9 is a square flat plate body having substantially the same size as the heat radiating portion 8b, and a large number of linear mounting grooves 10 which are substantially parallel to each other (six in the figure) are provided on the upper surface in FIG. Has been formed. On the other hand, the lower surface of each heat transfer plate 9 is formed into a flat surface. In addition, each mounting groove 10 has a U-shaped cross section in which the groove opening portion has a width substantially equal to the outer diameter of the connecting heat pipe described later, and the groove bottom portion is an arc surface that follows the cross sectional shape of the connecting heat pipe. It is a groove. Furthermore, each mounting groove 10 is formed to a depth about the radius of the connecting heat pipe. Therefore,
In this specific example, the heat collecting heat pipe 8 and the heat transfer plate 9 constitute a main connector 11 corresponding to the first connector of the present invention.

Each mounting groove 10 has an outer diameter of 3 as an example.
One end (lower end) of the connecting heat pipe 12 in which pure water W is sealed is tightly fitted in a copper container having a circular cross section of about 4 mm. That is, each coupling heat pipe 12 is held by the heat transfer plate 9 with the lower surface of the container along the groove bottom of the mounting groove 10. Therefore, it is possible to attach and detach by moving in the direction indicated by the arrow (radial direction). The connecting heat pipes 12 are flexible, and the middle portion of the container can be freely bent.

The other ends of the six connecting heat pipes 12 are appropriately bent so as to pass through a gap between parts (not shown) provided inside the personal computer case 5, that is, a so-called dead space. Have been extended to.

On the other hand, on the upper wall portion of the personal computer case 5, the sub connector 1 corresponding to the second connector of the present invention is provided.
Two 3 are provided in a state of being shifted left and right in FIG. Each sub-connector 13 is composed of a set of heat dissipation heat pipes 14 and a heat transfer plate 15. More specifically, each heat transfer plate 15 is a square flat plate body made of copper, aluminum alloy, or the like. In addition, each heat transfer plate 15 has a flat upper surface in FIG. 3, and a plurality of linear mounting grooves 16 (three in the drawing) that are substantially parallel to each other on the lower surface.

Each mounting groove 16, like the mounting groove 10 provided in the main connector 11, has a groove bottom portion which is an arcuate surface following the cross-sectional shape of the coupling heat pipe 12, and the groove releasing portion is a coupling heat pipe. The groove has a U-shaped cross section and has a width substantially equal to the outer diameter of 12. The mounting grooves 16 are formed to a depth of about the radius of the connecting heat pipe 12.

The upper ends of the connecting heat pipes 12 are tightly fitted in the respective mounting grooves 16 (only one connecting heat pipe 12 is shown). In other words, each coupling heat pipe 12 is held by the heat transfer plate 15 in a state where the upper surface of the container is in close contact with the bottom of the groove. Of course, both can exchange heat. In addition, if necessary, the outer peripheral portion of the intermediate portion of each coupling heat pipe 12 that does not contact the heat transfer plates 9 and 15 may be heat-insulated. With this configuration, it is possible to reduce the heat released from the container to the internal space of the personal computer case 5 during the operation of the heat pipe.

On the upper surface of each heat transfer plate 15, a heat dissipation heat pipe 14 having a shape of a truncated pyramid smaller than the heat collecting heat pipe 8 is integrally attached. That is, the heat radiating heat pipe 14 has a square heat radiating portion 14b which is larger than the heating portion 14a and faces a heat radiating portion 14b having a square shape and a flat surface. Pure water (not shown) is enclosed in a container constructed by connecting the entire circumference of the above with an inclined side wall portion 14c, and the heating portion 14a is in close contact with each heat transfer plate 15.

Further, radiating fins 17 corresponding to the heat sink of the present invention are attached to the radiating portion 14c of each radiating heat pipe 14, respectively. The heat radiation fins 17 are heat radiation plates 17 made of, for example, a thin aluminum alloy.
A large number of a are arranged in parallel at narrow intervals, and the lower ends of these are integrated by welding or the like with an aluminum alloy base plate 17b having the same shape and size as the heat radiating portion 14c. The base plate 17b is the heating unit 14a.
Is the contact surface against. In addition, each radiation fin 17
Is fixed to the personal computer case 5 with the base plate 17b being flush with the upper wall surface of the personal computer case 5 and the heat radiating plate 17a being exposed to the outside of the personal computer case 5.

Next, the operation of the cooling structure for the electronic element constructed as described above will be described. When the CPU 7 generates heat due to the energization accompanying the use of the personal computer, the heat is first transferred to the heating portion 8a of the heat collecting heat pipe 8, and the working fluid accumulated at the bottom of the container is heated and evaporated. Therefore, the inner surface of the heating portion 8a is an evaporation portion. Further, the working fluid that has become vapor flows toward the heat radiating portion 8b having a low internal pressure, and the heat is removed from the inner surface of the heat radiating portion 8b to be condensed. Therefore, the inner surface of the heat radiating portion 8b becomes the condensing portion.

In this case, in the heat collecting heat pipe 8, since the area of the heat radiating portion 8b is formed to be about four times as large as the area of the heating portion 8a, a large amount of working fluid vapor is condensed. And has high heat transport capability.

The working fluid that has condensed and adhered to the inner wall surface of the heat radiating portion 8b is dropped onto the wall surface of the heating portion 8a directly or is transmitted to the inner surface of each inclined side wall portion 8c to reach the heating portion 8a. Bring to reflux. As described above, the inclined side wall portion 8c
Since all four sides of the heat radiating portion 8b are connected to the four sides of the heating portion 8a, the working fluid in the liquid phase circulates on the upper surface of the heating portion 8a so as to concentrate from almost all directions. To do. Therefore, the evaporation / condensation cycle of the working fluid is smoothly performed.

On the other hand, the heat of the CPU 7 radiated from almost the entire area of the heat radiating portion 8b is transmitted to the lower surface of the heat transfer plate 9 and also conducted through the heat transfer plate 9 itself, and from the inner surface of each mounting groove 10. It is transmitted to each coupling heat pipe 12. In that case, the lower surface of each coupling heat pipe 12 is closely adhered along the inner surface of each mounting groove 10 to ensure a large direct contact area between the two, and to the mounting groove 10 on the heat radiation side. Since the connecting heat pipe 12, which is the heat receiving side, is located on the upper side, the heat resistance between the two is small, so that the heat of the CPU 7 is absorbed by the six heat collecting heat pipes 8 and the heat transfer plate 9. Good transmission to the connecting heat pipe 12.

Then, each connecting heat pipe 12 starts its operation. These connecting heat pipes 12
The working fluid vapor W generated at the lower end portion of the ascends toward the upper end portion where both the internal pressure and the temperature are low, that is, the end portion provided in the sub-connector 15, and the heat is removed by the heat transfer plate 15 there. To condense. In that case, the upper surface of the container of each connection heat pipe 12 is closely adhered along the inner surface of each mounting groove 16, and the direct contact area between the two is large, and in addition to the connection heat pipe 12 on the heat radiation side, On the other hand, since the heat transfer plate 15 on the heat receiving side is located on the upper side, the heat resistance between the two is small, and therefore heat is efficiently transferred to each of the two heat transfer plates 15.

Then, the heat is conducted through the heat transfer plate 15 itself, and from the upper surface in FIG.
Is transmitted to the heating unit 14a. In that case, the heating unit 14a
, And the entire upper surface of the heat transfer plate 15 are in surface contact with each other, so that the thermal resistance between them is small.

As described above, when heat is input to the heating section 14a, the two heat radiating heat pipes 14 respectively start operating. The working fluid that has become vapor on the inner surface of the heating portion 14a flows upward, and the heat is deprived and condensed on the inner surface of the heat radiating portion 14b. In that case, each heat radiation heat pipe 14
Similar to the heat collecting heat pipe 8, the heat radiating portion 14b is larger than the heating portion 14a in a hollow flat shape, and a large amount of working fluid vapor is condensed, and the working fluid in the liquid phase is heated by the heating portion 14a. Since it is refluxed so as to be concentrated in, the evaporation / condensation cycle of the working fluid is smoothly performed, and as a result, the heat transport capacity is high.

Therefore, heat is satisfactorily transferred from the upper surface of each heat radiation portion 14b to the lower surface of the base plate 17b of each heat radiation fin 17. Then, the heat of the CPU 7 is conducted toward the upper ends of the large number of heat dissipation plates 17a and is radiated into the air outside the personal computer case 5. Therefore, the CPU 7 is appropriately cooled, and overheating during use of the personal computer is prevented.

Here, in the heat collecting heat pipe 8 and the heat radiating heat pipe 14, even if the heat radiating portions 8b, 14b are set to have the same area as that of the conventional flat type heat pipe, the heating portion 8 is formed.
Since the area of a and 14a is small, it becomes a small container, and the occupied space is small. In addition, each heat transfer plate 9, 15
Is formed in a so-called half shape, so that the heat transfer plate covers the entire outer circumference of the connecting heat pipe 12, that is, the heat transfer has a circular hole into which the connecting heat pipe 12 is inserted. The plate thickness is thinner than the plate. That is, the heat transfer plates 9 and 15 shown in this specific example are configured to have the smallest possible contact area with the coupling heat pipe 12 and the smallest possible thickness.

By the heat transfer plates 9 and 15 and the heat collecting heat pipe 8 and the heat radiating heat pipe 14 configured as described above, the main connector 11 and the sub connector 13 are provided.
In addition to the above structure, the six connecting heat pipes 12 are all disposed in the dead space. Therefore, in the cooling structure of this specific example, the entire structure is made smaller than the conventional cooling structure. However, the cooling capacity can be improved. There is also an advantage that the main connector 11 and the connecting heat pipe 12 can be easily attached and detached, and the sub-connector 13 and the connecting heat pipe 12 can be easily attached and detached.

In the above specific example, the sub connector 13
Although the two heat dissipation fins 17 are exposed to the outside of the personal computer case 5 as an example, the present invention is not limited to the above specific example, and any number of sub-connectors 13 may be installed. Alternatively, the heat radiation heat pipe 12 may be exposed to the outside of the personal computer case 5. Further, the mounting grooves 10 and 16 formed on the heat transfer plates 9 and 15 may be replaced with U-shaped cross sections and formed into a circular hole shape that covers the entire outer circumference of the coupling heat pipe 12.

[0043]

As is apparent from the above description, according to the invention described in claim 1, the electronic device installed inside the housing is provided with the first connector so as to be able to exchange heat, and has a small diameter. The flexible connector heat pipe has one end that is capable of exchanging heat with the first connector, and the heat sink provided so as to be exposed to the outside of the housing is provided with the second connector capable of exchanging heat. In addition, since the other end of the connecting heat pipe is held by the second connector so that heat can be transferred, a cooling structure for an electronic element having a high cooling capacity for the electronic element and a compact structure can be obtained.

Further, as described in claim 2, if the mounting groove is formed so that the end portion of the connecting heat pipe is closely fitted to the first connector and the second connector, the connecting groove is formed. Since the direct contact area between the heat pipe and the first connector and the second connector is increased, the cooling capacity for the electronic element can be further improved.
Further, the connecting / disconnecting operation of the connecting heat pipe and the first connector and the second connector can be easily performed.

Further, as described in claim 3, the container is provided with a flat heating portion, a heat radiating portion having a larger area than the heating portion and spaced apart so as to face the heating portion. The first connector and the second connector are constituted by the heat pipe which is hollow and flat by the side wall portions which are connected to each other along the circumference, and the electronic element is disposed in the heating portion of the first connector, and the first connector is further arranged. By disposing the end of the connecting heat pipe in the heat dissipating part and the heating part of the second connector, and disposing the heat sink in the heat dissipating part of the second connector, between the first connector and the connecting heat pipe, Also, since the thermal resistance between the connection heat pipe and the second connector is reduced, the cooling capacity can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a specific example of the present invention.

FIG. 2 is a schematic view showing a main connector and a connecting heat pipe.

FIG. 3 is a schematic view showing a sub-connector and a connecting heat pipe.

FIG. 4 is a schematic view showing a conventional heat pipe for cooling a personal computer.

[Explanation of symbols]

5 ... PC case, 7 ... CPU, 10 ... Mounting groove, 11 ... Main connector, 12 ... Heat pipe for connection, 13 ... Sub connector, 16 ... Mounting groove,
17 ... Radiating fins.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuuji Saito 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Ltd. (72) Inventor Hitoshi Hasegawa 1-1-5 Kiba, Koto-ku, Tokyo Shareholders In Fujikura Ltd. (72) Inventor Katsuo Eguchi 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Ltd. (72) Inventor Tan Newen 1-1-5 Kiba, Koto-ku, Tokyo Incorporation Fujikura Ltd.

Claims (3)

[Claims] 1. A cooling structure for an electronic element, wherein an electronic element that generates heat is installed inside a housing, and a heat sink for the electronic element is installed so as to be exposed to the outside from the housing. A first connector is arranged so that heat can be exchanged, a second connector is arranged at the heat sink so that heat can be exchanged, and one end of a flexible connecting heat pipe having a small diameter is A cooling structure for an electronic element, which is held by one connector so that heat can be transferred, and the other end of the connecting heat pipe is held by the second connector so that heat can be transferred. 2. A mounting groove is formed in each of the first connector and the second connector so as to fit the ends of the connecting heat pipes in a state of closely adhering to each other. 1. A cooling structure for an electronic device according to 1. 3. A flat heating part, and a heat radiating part which is spaced apart so as to face the heating part and has a larger area than the heating part.
Inside the container formed into a flat hollow shape by the side wall portions that connect the peripheral portions of the heating portion and the heat radiating portion to each other over the entire circumference, the condensable fluid in the vacuum degassed state is the working fluid. The first connector and the second connector are respectively constituted by the heat pipe enclosed as the above, the electronic element is arranged in the heating portion of the first connector, and the heat radiating portion of the first connector and the heating of the second connector are further arranged. 3. The electronic device according to claim 1 or 2, wherein an end portion of the connecting heat pipe is provided in the portion and the heat sink is provided in the heat radiating portion of the second connector. Element cooling structure.