JP6928841B2 - heat pipe - Google Patents

Description

The present invention relates to a heat pipe having a good maximum heat transfer amount, a small thermal resistance, and excellent heat transfer characteristics.

Electronic components such as semiconductor elements mounted on electrical and electronic devices such as desktop personal computers and servers increase the amount of heat generated due to high-density mounting due to higher functionality, and its cooling is becoming more important. Heat pipes may be used as a cooling method for electronic components.

In addition, heat pipes may be installed in cold regions. If the heat pipe is installed in a cold region, the working fluid enclosed in the container may freeze and the heat pipe may not operate smoothly. Therefore, when the working fluid is frozen by a heat pipe type cooler in which the amount of the working fluid of at least one of the plurality of heat pipes is 35 to 65% of the amount of the working fluid of the other heat pipes, First, it has been proposed to shorten the time required for activation by first melting the working fluid of a heat pipe having a small amount of working fluid and a small heat capacity (Patent Document 1).

However, in Patent Document 1, since the working fluid is still liable to freeze in a cold region, there is a problem that the volume expands when the working fluid freezes, and the container may be deformed or destroyed. Further, if the container is deformed, there is a problem that it may hit other members such as a liquid crystal display and a battery arranged around the heat pipe and damage the container. Further, since the clearance inside the container of the heat pipe is narrow, there is a problem that the deformation and destruction of the container may become more remarkable due to the volume expansion due to the freezing of the working fluid.

Further, in a cold region, the heat pipe may be installed in a bottom heat state in which the longitudinal direction of the container is substantially parallel to the direction of gravity. When the heat pipe is installed in the bottom heat position, the working fluid of the liquid phase accumulates at the bottom of the container, especially when the heat pipe is not in operation. In cold regions, when the working fluid of the liquid phase stored at the bottom of the container freezes and the volume of the working fluid expands, there is a problem that the container is deformed and destroyed more frequently. In addition, if antifreeze is used to prevent the working fluid from freezing, or if the wall thickness of the container is increased to prevent deformation or destruction of the container due to freezing of the working fluid, the heat transport characteristics of the heat pipe will deteriorate. There was a problem that it would end up.

Japanese Unexamined Patent Publication No. 10-274487

In view of the above circumstances, the present invention is installed in a cold region in a bottom heat posture in which the longitudinal direction of the container is substantially parallel to the direction of gravity, and even if the working fluid freezes, the container can be prevented from being deformed. , It is an object of the present invention to provide a heat pipe having excellent heat transport characteristics.

Aspects of the present invention include a container having a tube shape in which an end face of one end and an end face of the other end are sealed and having an inner wall surface in which a groove is formed, and one end of the container. A heat pipe provided with a sintered body layer in which powder is sintered and a working fluid sealed in a cavity of the container, which is provided on the inner wall surface of the container. It has a first sintered portion located on the end face side of the one end portion and a second sintered portion continuous with the first sintered portion and located on the other end side. , The average primary particle size of the first powder used as the raw material of the first sintered portion is smaller than the average primary particle size of the second powder used as the raw material of the second sintered portion. Is.

In the above aspect, the sintered body layer is provided at at least one end of the inner wall surface of the container. Further, the inner wall surface of the container has a portion where the groove portion is exposed and a portion covered with the sintered body layer. A boundary portion between the first sintered portion and the second sintered portion is formed in the sintered body layer having the first sintered portion and the second sintered portion. Further, since the average primary particle size of the first powder which is the raw material of the first sintered portion is smaller than the average primary particle size of the second powder which is the raw material of the second sintered portion, the first The capillary force of the first sintered portion is larger than the capillary force of the second sintered portion, and the flow path resistance of the liquid phase to the working fluid inside the second sintered portion is the first sintered portion. Smaller than the inside.

Further, in the above aspect, the first sintered portion of one end of the container in which the longitudinal direction of the container is installed in a bottom heat posture substantially parallel to the gravity direction and the sintered body layer is provided. When the part corresponding to the above is made to function as a heat receiving part and the other end as a heat radiating part, the working fluid of the liquid phase recirculated from the radiating part to the end face of one end of the container and its vicinity has a relative capillary force. Due to the capillary action of the first sintered portion having a large size, the inside of the first sintered portion is smoothly diffused from the end face of one end and its vicinity in the direction of the second sintered portion (approximately opposite to the direction of gravity). I will do it. The working fluid of the liquid phase diffused inside the first sintered portion receives heat from the object to be cooled and undergoes a phase change from the liquid phase to the gas phase. The working fluid whose phase has changed from the liquid phase to the gas phase flows from the heat receiving portion to the heat radiating portion, and releases latent heat at the heat radiating portion. The working fluid that releases latent heat and undergoes a phase change from the gas phase to the liquid phase is returned from the heat radiation portion of the container to the end face of one end and its vicinity by the capillary force and gravity of the groove. Further, when the heat pipe is not in operation, the working fluid of the liquid phase that has flowed back to the end face of one end of the container and its vicinity does not collect in the end face of one end and its vicinity. A working fluid that smoothly diffuses inside the first sintered portion in the direction of the second sintered portion (in a direction substantially opposite to the direction of gravity), and further diffuses from the inside of the first sintered portion to the inside of the second sintered portion. Diffuses inside the second sintered portion at a diffusion rate faster than that inside the first sintered portion. Therefore, when the heat pipe is not in operation, the working fluid in the liquid phase smoothly diffuses inside the second sintered portion.

Aspects of the present invention include a container having a tube shape in which an end face of one end and an end face of the other end are sealed and having an inner wall surface in which a groove is formed, and a central portion in the longitudinal direction of the container. A heat pipe provided with a sintered body layer in which powder is sintered and a working fluid sealed in a cavity of the container, which is provided on the inner wall surface of the container. A first sintered portion located in the central portion of the sintered body layer and a second sintered portion connected to the first sintered portion and located at both ends of the sintered body layer. The average primary particle size of the first powder, which is the raw material of the first sintered portion, is smaller than the average primary particle size of the second powder, which is the raw material of the second sintered portion. , The sintered body layer is not provided at both ends in the longitudinal direction of the container, and the grooves are exposed at both ends in the longitudinal direction of the container.

An aspect of the present invention is a heat pipe in which the ratio of the average primary particle size of the first powder to the average primary particle size of the second powder is 0.3 to 0.9.

An aspect of the present invention is a heat pipe further provided with a convex sintered body in which powder is sintered, which protrudes from the sintered body layer in a cross section perpendicular to the longitudinal direction of the container.

An aspect of the present invention is a heat pipe in which the wall thickness (T1) of the container at the bottom of the groove / the thickness (T2) of the sintered body layer at the top of the groove is 0.30 to 0.80. be.

An aspect of the present invention is a heat pipe in which the area of the sintered body layer (A1) / the area of the cavity (A2) is 0.30 to 0.80 in a cross section perpendicular to the longitudinal direction of the container. be.

In an aspect of the present invention, in a cross section perpendicular to the longitudinal direction of the container, (area of the sintered body layer (A1) + area of the convex sintered body (A3)) / area of the cavity portion (A2). Is a heat pipe of 1.2 to 2.0.

An aspect of the present invention is a heat pipe in which the length of the first sintered portion / the length of the second sintered portion is 0.2 to 3.0 in the longitudinal direction of the container.

According to the aspect of the present invention, the average primary particle size of the first powder which is the raw material of the first sintered portion is the average primary particle diameter of the second powder which is the raw material of the second sintered portion. Since it is smaller than, the capillary force of the first sintered portion is larger than the capillary force of the second sintered portion. Therefore, by using the first sintered portion as the heat receiving portion, the longitudinal direction of the container becomes gravity. Even if it is installed in a bottom heat posture substantially parallel to the direction, it is possible to reliably prevent the working fluid of the liquid phase from drying out in the heat receiving portion, and it is possible to exhibit excellent heat transport characteristics. Further, since the flow path resistance of the liquid phase to the working fluid inside the second sintered portion is smaller than that inside the first sintered portion, the liquid phase operates even when the heat pipe is not operating. The liquid rapidly diffuses inside the second sintered portion through the first sintered portion. Therefore, even when the heat pipe is not in operation, it is possible to prevent the liquid phase working fluid from accumulating in the end face of one end of the container and its vicinity, so that freezing of the liquid phase working fluid is suppressed. Further, even if the working fluid of the liquid phase freezes, the local liquid accumulation of the working fluid of the liquid phase is prevented, so that the local volume expansion of the working fluid is alleviated and the deformation of the container can be prevented. ..

In addition, it is not necessary to use antifreeze, and a thin container can be used, so that excellent heat transport characteristics are exhibited.

According to the aspect of the present invention, the ratio of the average primary particle size of the first powder to the average primary particle size of the second powder is 0.3 to 0.9, so that the first sintering It is possible to improve the capillary force inside the portion and the reduction performance of the flow path resistance inside the second sintered portion in a well-balanced manner.

According to the aspect of the present invention, since the convex sintered body protruding from the sintered body layer is further provided, the local liquid pool of the working fluid of the liquid phase is further reduced, so that the container Deformation can be prevented more reliably.

According to the aspect of the present invention, the thickness of the container at the bottom of the groove (T1) / the thickness of the sintered body layer at the top of the groove (T2) is 0.30 to 0.80, so that the liquid phase It is possible to obtain excellent flowability of the working fluid in the gas phase while surely preventing the liquid accumulation of the working fluid.

According to the aspect of the present invention, the area of the sintered body layer (A1) / the area of the cavity (A2) is 0.30 to 0.80, or (the area of the sintered body layer (A1) + convex). Since the area of the state sintered body (A3)) / the area of the cavity (A2) is 1.2 to 2.0, the working fluid of the liquid phase is surely prevented from accumulating, and the gas phase is operated. Excellent fluid flowability can be obtained.

(A) is a side sectional view of the heat pipe according to the first embodiment of the present invention, and (b) is a sectional view taken along the line AA of FIG. (A). It is a front sectional view of the heat pipe which concerns on 2nd Embodiment of this invention. It is a front sectional view of the heat pipe which concerns on 3rd Embodiment of this invention. It is a front sectional view of the heat pipe which concerns on 4th Embodiment of this invention. It is a front sectional view of the heat pipe which concerns on 5th Embodiment of this invention. It is a front sectional view of the heat pipe which concerns on 6th Embodiment of this invention. It is a side sectional view of the heat pipe which concerns on 7th Embodiment of this invention. It is explanatory drawing of the usage example of the heat pipe which concerns on embodiment of this invention.

Hereinafter, the heat pipe according to the first embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1A, the heat pipe 1 according to the first embodiment includes a tube-shaped container 10 in which the end face of one end 11 and the end face of the other end 12 are sealed. The powder provided on the inner wall surface of the inner wall surface of the container 10 and the groove portion 13 formed of a plurality of fine grooves formed along the longitudinal direction of the container 10 and the inner wall surface of one end portion 11 of the container 10 was sintered. It includes a sintered body layer 14 and a working fluid (not shown) sealed in the cavity 17 of the container 10.

The container 10 is a sealed, substantially straight pipe material, and has a substantially circular cross-sectional shape in a direction orthogonal to the longitudinal direction (that is, perpendicular to the longitudinal direction). The wall thickness of the container 10 is not particularly limited, but is, for example, 50 to 1000 μm. The radial dimension of the container 10 is not particularly limited, but is, for example, 5 to 20 mm.

As shown in FIGS. 1 (a) and 1 (b), the inner wall surface of the container 10 has a groove portion composed of a plurality of fine grooves along the longitudinal direction of the container 10 from one end 11 to the other end 12. 13, that is, a groove is formed. Further, the groove portion 13 is formed on the entire inner peripheral surface of the container 10.

Of the inner wall surface of the container 10 in which the groove portion 13 is formed, one end portion 11 is provided with a sintered body layer 14 in which powder is sintered. The sintered body layer 14 is formed on the entire inner peripheral surface of the container 10. Therefore, on the inner wall surface of one end portion 11, the groove portion 13 is covered with the sintered body layer 14. In the heat pipe 1, the sintered body layer 14 is not provided at the other end portion 12 and the central portion 19 of the container 10. Therefore, in the other end portion 12 and the central portion 19 of the container 10, the groove portion 13 is exposed to the internal space (cavity portion 17) of the container 10.

Further, the sintered body layer 14 is continuous with the first sintered portion 15 adjacent to the end face of one end portion 12 and the first sintered portion 15, and is located on the other end portion 12 side. It has a sintered portion 16 of the above. A boundary portion 18 is formed at the boundary between the first sintered portion 15 and the second sintered portion 16. In the heat pipe 1, a first sintered portion 15 is also provided on the end face of one end portion 12.

The first sintered portion 15 is a first powder sintered body, and the second sintered portion 16 is a second powder sintered body. The average primary particle size of the first powder, which is the raw material of the first sintered portion 15, is smaller than the average primary particle size of the second powder, which is the raw material of the second sintered portion 16. Therefore, the average value of the cross-sectional areas of the voids formed inside the second sintered portion 16 is larger than the average value of the cross-sectional areas of the voids formed inside the first sintered portion 15. ing. That is, since the average primary particle size of the first powder is smaller than the average primary particle size of the second powder, the capillary force of the first sintered portion 15 is larger than the capillary tube force of the second sintered portion 16. The flow path resistance of the working fluid of the liquid phase inside the second sintered portion 16 is smaller than the flow path resistance of the working fluid of the liquid phase inside the first sintered portion 15.

The ratio of the average primary particle size of the first powder to the average primary particle size of the second powder is not particularly limited, but the capillary force inside the first sintered portion 15 and the second sintered portion 16 From the viewpoint of reducing the internal flow path resistance, 0.3 to 0.9 is preferable, and 0.4 to 0.8 is particularly preferable. If the average primary particle size of the first powder is smaller than the average primary particle size of the second powder, the average primary particle size of the first powder and the average primary particle size of the second powder The particle size is not particularly limited, but for example, the average primary particle size of the first powder is preferably 10 μm or more and less than 90 μm, and the average primary particle size of the second powder is preferably 90 μm or more and 250 μm or less. For example, by separating the powder with a sieve, a powder in the above average primary particle size range can be obtained.

As shown in FIGS. 1 (a) and 1 (b), the internal space of the container 10 is a hollow portion 17, and the hollow portion 17 is a vapor flow path for the working fluid of the gas phase. That is, at one end 11 of the container 10, the surface of the sintered body layer 14 and at the other end 12 and the central 19 of the container 10, the inner wall surface of the container 10 in which the groove 13 is formed are vapors, respectively. It is the wall surface of the flow path.

The value of the wall thickness (T1) of the container 10 at the bottom of the fine groove forming the groove 13 / the thickness (T2) of the sintered body layer 14 at the top of the fine groove forming the groove is not particularly limited, but is a liquid phase. 0.30 or more is preferable, 0.40 or more is more preferable, and 0.45 or more is particularly preferable, from the viewpoint of surely preventing the liquid accumulation of the working fluid. On the other hand, the upper limit of (T1) / (T2) is preferably 0.80 or less from the viewpoint of the flowability of the working fluid in the gas phase.

The value of the area (A1) of the sintered body layer 14 / the area (A2) of the cavity 17 in the cross section perpendicular to the longitudinal direction of the container 10 is not particularly limited, but ensures that the working fluid of the liquid phase collects. From the viewpoint of prevention, 0.30 or more is preferable, 0.40 or more is more preferable, and 0.45 or more is particularly preferable. On the other hand, the above (A1) / (A2) is preferably 0.80 or less from the viewpoint of the flowability of the working fluid in the gas phase.

The value of the length (L1) of the first sintered portion 15 / the length (L2) of the second sintered portion 16 in the longitudinal direction of the container 10 is not particularly limited, but at one end portion 11, the value is not particularly limited. From the viewpoint of reliably preventing the working fluid of the liquid phase from drying out and collecting liquid, 0.2 to 3.0 is preferable, and 0.7 to 1.7 is particularly preferable.

The material of the container 10 is not particularly limited, and for example, copper or copper alloy may be used from the viewpoint of excellent thermal conductivity, aluminum or aluminum alloy from the viewpoint of light weight, stainless steel or the like from the viewpoint of improving strength. .. In addition, tin, tin alloy, titanium, titanium alloy, nickel, nickel alloy and the like may be used depending on the usage conditions. The materials of the first powder and the second powder, which are the raw materials of the sintered body layer 14, are not particularly limited, and examples thereof include powders containing metal powders. Specific examples thereof include copper powders. And metal powder such as stainless steel powder, mixed powder of copper powder and carbon powder, nanoparticles of the above powder, and the like can be mentioned. Therefore, as the sintered body layer 14, a sintered body of powder containing metal powder can be mentioned, and specific examples thereof include a sintered body of metal powder such as copper powder and stainless steel powder, and copper powder and carbon powder. Examples thereof include a sintered body of a mixed powder with and a sintered body of the above-mentioned powder nanoparticles. The material of the first powder and the material of the second powder may be the same or different.

The working fluid to be sealed in the container 10 can be appropriately selected depending on the compatibility with the material of the container 10, and examples thereof include water, CFC substitutes, perfluorocarbons, and cyclopentane.

Next, the mechanism of heat transport of the heat pipe 1 according to the first embodiment of the present invention will be described. When the heat pipe 1 receives heat from a heating element (not shown) thermally connected at a portion of the one end portion 11 where the first sintered portion 15 is provided, the heat pipe 1 receives heat from the one end portion 11. The portion provided with the first sintered portion 15 functions as a heat receiving portion, and the working fluid undergoes a phase change from the liquid phase to the gas phase at the heat receiving portion. The working fluid that has undergone a phase change to the gas phase flows through the steam flow path, which is the cavity 17, from the heat receiving portion to the heat radiating portion, which is the other end 12, in the longitudinal direction of the container 10, so that heat from the heating element is generated. It is transported from the heat receiving part to the heat radiating part. The heat from the heating element transported from the heat receiving part to the heat radiating part is released as latent heat by the phase change of the working fluid of the gas phase to the liquid phase at the heat radiating part provided with the heat exchange means (not shown). Will be done. The latent heat released by the heat radiating section is released from the heat radiating section to the external environment of the heat pipe 1 by the heat exchange means provided in the heat radiating section. The working fluid whose phase has changed to a liquid phase in the heat radiating portion is returned from the heat radiating portion to the heat receiving portion by the capillary force of the groove portion 13.

In the heat pipe 1 according to the first embodiment, the average primary particle size of the first powder which is the raw material of the first sintered portion 15 is the second powder which is the raw material of the second sintered portion 16. Since it is smaller than the average primary particle size of the body, the capillary force of the first sintered portion 15 is larger than the capillary force of the second sintered portion 16. Therefore, by using the first sintered portion 15 as the heat receiving portion, even if the container 10 is installed in a bottom heat posture substantially parallel to the gravitational direction, the working fluid of the liquid phase in the heat receiving portion Dry-out can be reliably prevented and excellent heat transport characteristics can be exhibited. Further, since the flow path resistance of the liquid phase to the working fluid inside the second sintered portion 16 is smaller than that inside the first sintered portion 15, the liquid phase operates even when the heat pipe 1 is not operating. The liquid quickly diffuses from the end face of one end 11 of the container 10 and its vicinity to the inside of the second sintered portion 16 via the first sintered portion 15. Therefore, even when the heat pipe 1 is not in operation, it is possible to prevent the liquid phase working fluid from accumulating in the end face of one end 11 of the container 10 and its vicinity, so that freezing of the liquid phase working fluid is suppressed. NS. Further, even when the working fluid of the liquid phase freezes, local liquid pooling of the working fluid of the liquid phase (liquid pooling at the end face of one end 11 and its vicinity) is prevented, so that the working fluid is locally located. Volume expansion is alleviated, and deformation of the container 10 can be prevented.

Further, in the heat pipe 1, since the local volume expansion due to freezing of the working fluid is alleviated, it is not necessary to use an antifreeze liquid, and the thin container 10 can be used, which is also excellent in heat transport characteristics. Demonstrate.

Next, the heat pipe according to the second embodiment of the present invention will be described with reference to the drawings. The same components as the heat pipe according to the first embodiment will be described with reference to the same reference numerals.

As shown in FIG. 2, in the heat pipe 2 according to the second embodiment, in a cross section perpendicular to the longitudinal direction of the container 10, a convex sintering in which powder is sintered protruding from the sintered body layer 14 A body 24 is further provided. The sintered body layer 14 and the convex sintered body 24 are in a continuous manner. In the heat pipe 2, one convex sintered body 24 is provided, and the tip (top) of the convex sintered body 24 is not in contact with the opposing sintered body layer 14.

In the heat pipe 2, the convex sintered body 24 extends from the first sintered portion 15 to the second sintered portion 16. That is, the convex sintered body 24 is provided in the first sintered portion 15 and the second sintered portion 16. The convex sintered body 24 in the first sintered portion 15 is a sintered body made from the first powder. The convex sintered body 24 in the second sintered portion 16 is a sintered body made from the second powder.

In the cross section perpendicular to the longitudinal direction of the container 10, (the area of the sintered body layer 14 (A1) + the area of the convex sintered body 24 (A3)) / the area of the cavity 17 (A2) is not particularly limited. , 1.2 or more is preferable, and 1.3 or more is particularly preferable, from the viewpoint of surely preventing the liquid accumulation of the working fluid in the liquid phase. On the other hand, the upper limit of the values of ((A1) + (A3)) / (A2) is preferably 2.0 or less from the viewpoint of the flowability of the working fluid in the gas phase.

By further providing the convex sintered body 24, the working fluid of the liquid phase is not only the sintered body layer 14 arranged near the outer periphery of the container 10, but also its cross section perpendicular to the longitudinal direction of the container 10. Since it also diffuses into the convex sintered body 24 extending toward the central portion, local liquid pooling can be further reduced, and deformation of the container can be prevented more reliably.

Next, the heat pipe according to the third embodiment of the present invention will be described with reference to the drawings. The same components as the heat pipes according to the first and second embodiments will be described with reference to the same reference numerals.

The heat pipe according to the second embodiment is provided with one convex sintered body, but instead, as shown in FIG. 3, the heat pipe 3 according to the third embodiment is convex. A plurality of shaped sintered bodies (two in FIG. 3) are provided. That is, in the heat pipe 3, the convex sintered body 24 is a second convex sintered body facing the first convex sintered body 24-1 and the first convex sintered body 24-1. It consists of 24-2. In the heat pipe 3, the first convex sintered body 24-1 and the second convex sintered body 24-2 are not in contact with each other.

Since the convex sintered body 24 is further provided in the heat pipe 3, the working fluid of the liquid phase is not only the sintered body layer 14 near the outer periphery of the container 10, but also the cross section perpendicular to the longitudinal direction of the container 10. Since it also diffuses into the convex sintered body 24 extending toward the central portion thereof, local liquid pooling can be further reduced, and deformation of the container can be prevented more reliably.

Next, the heat pipe according to the fourth embodiment of the present invention will be described with reference to the drawings. The same components as the heat pipes according to the first to third embodiments will be described with reference to the same reference numerals.

In the heat pipe according to the first embodiment, the cross-sectional shape in the direction orthogonal to the longitudinal direction of the container is substantially circular, but instead, as shown in FIG. 4, the fourth embodiment is used. In the heat pipe 4, the cross-sectional shape of the container 10 in the direction orthogonal to the longitudinal direction is a flat shape including a flat portion and a semi-elliptical portion. That is, the container 10 is flattened. Even in the heat pipe 4 or in the state where the heat pipe 4 is not in operation, it is possible to prevent the liquid phase working fluid from accumulating in the end face of one end 11 of the container 10 and its vicinity. Further, since the container 10 of the heat pipe 4 has a flat portion, the thermal connectivity with the heating element to be cooled is improved.

Next, the heat pipe according to the fifth embodiment of the present invention will be described with reference to the drawings. The same components as the heat pipes according to the first to fourth embodiments will be described with reference to the same reference numerals.

In the heat pipe according to the second embodiment in which one convex sintered body is provided, the cross-sectional shape in the direction orthogonal to the longitudinal direction of the container is substantially circular. As shown in 5, in the heat pipe 5 according to the fifth embodiment, the cross-sectional shape in the direction orthogonal to the longitudinal direction of the container 10 is a flat shape including a flat portion and a semi-elliptical portion. .. Even in the heat pipe 5 or in the state where the heat pipe 5 is not in operation, it is possible to prevent the liquid phase working fluid from accumulating in the end face of one end 11 of the container 10 and its vicinity. Further, since the container 10 of the heat pipe 5 has a flat portion, the thermal connectivity with the heating element to be cooled is improved.

Next, the heat pipe according to the sixth embodiment of the present invention will be described with reference to the drawings. The same components as the heat pipes according to the first to fifth embodiments will be described with reference to the same reference numerals.

In the heat pipe according to the third embodiment in which two convex sintered bodies are provided, the cross-sectional shape in the direction orthogonal to the longitudinal direction of the container is substantially circular. As shown in 6, in the heat pipe 6 according to the sixth embodiment, the cross-sectional shape in the direction orthogonal to the longitudinal direction of the container 10 is a flat shape including a flat portion and a semi-elliptical portion. .. Even in the heat pipe 6 or in the state where the heat pipe 6 is not in operation, it is possible to prevent the liquid phase working fluid from accumulating in the end face of one end 11 of the container 10 and its vicinity. Further, since the container 10 of the heat pipe 6 has a flat portion, the thermal connectivity with the heating element to be cooled is improved.

Next, the heat pipe according to the seventh embodiment of the present invention will be described with reference to the drawings. The same components as the heat pipes according to the first to sixth embodiments will be described with reference to the same reference numerals.

In each of the above embodiments, the sintered body layer is provided at one end of the heat pipe, but instead, as shown in FIG. 7, in the heat pipe 7 according to the seventh embodiment, the heat pipe 7 is provided. The sintered body layer 14 is provided at the central portion in the longitudinal direction of the container 10, and the sintered body layer 14 is not provided at both ends in the longitudinal direction of the container 10. In the heat pipe 7 according to the seventh embodiment, the shape of the container 10 in the longitudinal direction is substantially U-shaped, and the sintered body layer 14 is provided at the bent portion and its vicinity. Further, the first sintered portion 15 is provided in the central portion in the longitudinal direction of the sintered body layer 14, and the second sintered portion 16 continuous with the first sintered portion 15 is the sintered body layer 14. It is provided at both ends in the longitudinal direction of the. In the heat pipe 7, the same effect as described above is obtained when the central portion of the container 10 in the longitudinal direction serves as a heat receiving portion that is thermally connected to the heating element 100 and both ends of the container 10 in the longitudinal direction serve as heat radiating portions. Demonstrate.

Next, an example of a method for manufacturing a heat pipe of the present invention will be described. First, an example of a method for manufacturing a heat pipe according to the first embodiment will be described. The manufacturing method is not particularly limited, but for example, in the heat pipe according to the first embodiment, a core having a predetermined shape is formed at one end of a circular pipe material having a groove formed on an inner wall surface in the longitudinal direction. Insert the stick. In the gap formed between the inner wall surface of the pipe material and the outer surface of the core rod, the first powder which is the raw material of the first sintered portion and the second powder which is the raw material of the second sintered portion are formed. The powder is sequentially filled. Next, the pipe material filled with the first powder and the second powder is heat-treated, and the core rod is pulled out from the pipe material, so that the first sintered portion and the second sintered portion are separated from each other at one end. It is possible to manufacture a heat pipe having a part.

Further, in the heat pipe provided with the convex sintered body, a core rod having a predetermined cutout portion is inserted, and not only the gap portion formed between the inner wall surface of the pipe material and the outer surface of the core rod, but also the gap portion is formed. The first powder, which is the raw material of the first sintered portion, and the second powder, which is the raw material of the second sintered portion, are also formed in the gaps formed between the inner wall surface of the pipe material and the notch portion. It can be produced by sequentially filling the powder and then heat-treating it.

Next, an example of how to use the heat pipe of the present invention will be described. Here, as shown in FIG. 8, in the heat pipe 1 according to the first embodiment, the container 10 having a substantially linear shape in the longitudinal direction is replaced with a container having a substantially L-shape in the longitudinal direction. A heat pipe 8 using 10 and further provided with a plurality of heat radiation fins 30 at the other end portion 12 (heat sink) will be described.

When cooling the heating element in the heat pipe 8, for example, the size of the first sintered portion 15 in the longitudinal direction of the container 10 is such that heat is generated from one end 11 of the container 10 to the other end 12. If the dimension is set to the end of the body 100, or 10 to 50% of the dimension of the heating element 100 in the longitudinal direction of the container 10 even if it exceeds the end of the heating element 100 on the other end 12 side, the liquid is liquid. The effect of preventing liquid accumulation and the effect of heat transport of the working fluid of the phase can be exhibited more efficiently. Further, when the heat pipe 8 is thermally connected to the heating element 100 via the heat receiving plate 101, at least a part of the second sintered portion 16 is applied to the heat receiving plate 101 in the longitudinal direction of the container 10. When the dimensions of the sintered body layer 14 are set as described above, the effect of preventing liquid accumulation of the working fluid in the liquid phase and the effect of heat transport can be more efficiently exhibited.

Next, the heat pipe according to another embodiment of the present invention will be described. In the heat pipe according to the first to sixth embodiments, the sintered body layer is provided only at one end of the container, but instead, it extends from one end of the container to the center. It may be an existing aspect. Further, in the heat pipe according to the first to sixth embodiments, the shape of the container in the longitudinal direction is substantially linear, but the shape is not particularly limited, and for example, a U shape, an L shape, or the like. , The shape may have a bent portion.

In the heat pipe according to the third and sixth embodiments, the first convex sintered body and the second convex sintered body were not in contact with each other. The tip portions) may be in contact with each other. In this case, one steam flow path (cavity) is formed on each side of the convex sintered body. Further, in the heat pipes according to the second, third, fifth, and sixth embodiments, the convex sintered body extends from the first sintered portion to the second sintered portion. Instead, the convex sintered body may be provided only in the second sintered portion.

Next, examples of the present invention will be described, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

Examples 1-3
As the heat pipe, the heat pipe according to the first embodiment shown in FIG. 1 was used. Copper powder with an average primary particle diameter of 75 μm as the first powder that is the raw material of the first sintered portion (length 20 mm), and the second powder that is the raw material of the second sintered portion (length 25 mm). A copper powder having an average primary particle size of 140 μm was used as the powder. As the container, a pipe material (stainless steel) having a length of 200 mm and a circular cross section was used. Water was used as the working fluid to be sealed in the container. The heat pipe is installed so that the longitudinal direction is vertical and the sintered body layer is on the gravity direction side, and after being subjected to a heat shock test at -40 ° C × 23 minutes → 85 ° C × 23 minutes, it is visually formed into a container shape. The percentage of those with no deformation was measured as the OK rate (%).

Example 4
As the heat pipe, the same as in Examples 1 to 3 except that the heat pipe according to the second embodiment shown in FIG. 2 is used instead of the heat pipe according to the first embodiment shown in FIG. And said.

Comparative Examples 1 to 3
The same procedure as in Examples 1 to 3 was applied except that the first powder was used instead of the second powder as the raw material powder for the second sintered portion.

Specific test conditions and test results of Examples and Comparative Examples are shown in Table 1 below.

From Table 1, in Examples 1 to 4 in which two types of sintered portions, a first sintered portion and a second sintered portion, were provided as the sintered body layer, an excellent heat shock OK rate was obtained even in 100 cycles. Obtained. In particular, in Examples 1 and 2 in which T1 / T2 is 47 to 56% (0.47 to 0.56) and A1 / A2 is 58 to 69% (0.58 to 0.69), T1 / T2 The heat shock OK rate was further improved as compared with Example 3 in which the value was 68% (0.68) and A1 / A2 was 47% (0.47).

On the other hand, in Comparative Examples 1 to 3 in which one type of sintered portion was formed without providing the second sintered portion, T1 / T2 and A1 / A2 were T1 / T2 and T1 / T2 of Examples 1 to 3, respectively. Even if it was almost the same as A1 / A2, a good heat shock OK rate could not be obtained even in 50 cycles.

The heat pipe of the present invention is installed in a bottom heat posture in which the longitudinal direction of the container is substantially parallel to the direction of gravity, can prevent deformation of the container even if the working fluid freezes, and has excellent heat transport characteristics. For example, it has high utility value in the field of use in cold regions.

1, 2, 3, 4, 5, 6, 7 Heat pipe 10 Container 11 One end 13 Groove 14 Sintered body layer 15 First sintered part 16 Second sintered part 17 Hollow part 24 Convex firing Bound

Claims (7)

A container having a tube shape in which the end face of one end and the end face of the other end are sealed and having an inner wall surface on which a groove is formed,
A sintered body layer in which powder is sintered, which is provided on the inner wall surface of the central portion in the longitudinal direction of the container.
The working fluid sealed in the cavity of the container and
It is a heat pipe equipped with
The sintered body layer is continuous with the first sintered portion located in the central portion of the sintered body layer and the first sintered portion, and is located at both ends of the sintered body layer. With a sintered part,
The average primary particle size of the first powder, which is the raw material of the first sintered portion, is smaller than the average primary particle size of the second powder, which is the raw material of the second sintered portion.
The sintered body layer is not provided at both ends in the longitudinal direction of the container, and the grooves are exposed at both ends in the longitudinal direction of the container .
The shape of the container in the longitudinal direction is a shape having a bent portion, the first sintered portion is provided in a heat receiving portion thermally connected to a heating element, and the first sintered portion is provided inside and outside the bent portion. 2 sintered parts are provided,
A heat pipe in which the flow path resistance of the working fluid of the liquid phase inside the second sintered portion is smaller than the flow path resistance of the working fluid of the liquid phase inside the first sintered portion. The heat pipe according to claim 1, wherein the ratio of the average primary particle size of the first powder to the average primary particle size of the second powder is 0.3 to 0.9. The heat pipe according to claim 1 or 2, wherein a convex sintered body in which powder is sintered, which protrudes from the sintered body layer in a cross section perpendicular to the longitudinal direction of the container, is further provided. Any one of claims 1 to 3 in which the wall thickness (T1) of the container at the bottom of the groove / the thickness (T2) of the sintered body layer at the top of the groove is 0.30 to 0.80. The heat pipe described in the section. The heat according to claim 1 or 2, wherein the area of the sintered body layer (A1) / the area of the cavity (A2) is 0.30 to 0.80 in a cross section perpendicular to the longitudinal direction of the container. pipe. In the cross section perpendicular to the longitudinal direction of the container, (the area of the sintered body layer (A1) + the area of the convex sintered body (A3)) / the area of the cavity (A2) is 1.2 to The heat pipe according to claim 3, which is 2.0. The item according to any one of claims 1 to 6, wherein the length of the first sintered portion / the length of the second sintered portion is 0.2 to 3.0 in the longitudinal direction of the container. The heat pipe described.

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