CN215638972U

CN215638972U - Heat pipe

Info

Publication number: CN215638972U
Application number: CN202121089789.4U
Authority: CN
Inventors: 王证都; 高尾征志; 多田清志
Original assignee: Nidec Chaun Choung Technology Corp
Current assignee: Nidec Chaun Choung Technology Corp
Priority date: 2020-05-20
Filing date: 2021-05-20
Publication date: 2022-01-25
Anticipated expiration: 2031-05-20
Also published as: JP2021181872A

Abstract

The utility model provides a heat pipe, which is provided with a tubular container for accommodating a working medium and a porous core structure for conveying the working medium. The container has a bottom wall portion and an upper wall portion that are vertically opposed to each other in a cross section perpendicular to an extending direction of the container. The side wall portion connects both side end portions of the bottom wall portion and both side end portions of the upper wall portion, respectively. The core structure has a lower core structure and a pair of side core structures. The lower core structure is formed in contact with the bottom wall portion, and the upper surface thereof is disposed facing the internal space. The side core structures extend upward from both ends of the lower core structure along the side wall portions.

Description

Heat pipe

Technical Field

The present invention relates to a heat pipe as a heat conductive member.

Background

A conventional heat pipe includes a working medium such as water, a wick structure, and a container. The container is formed in a tubular shape, and accommodates the working medium and the core structure. The core structures are formed to face each other in the vertical direction from the upper and lower portions of the inner peripheral surface of the container.

The container is disposed in contact with the heating element. The working medium is heated by the heating element and vaporized from the side surface portion extending in the longitudinal direction of the core structure. The vaporized vapor moves to the heat radiation side in the heat pipe. On the heat radiation side, the vapor is cooled by heat radiation and liquefied. The working medium that becomes liquid moves toward the heat generating body side in the core structure by capillary phenomenon. Thereby, heat is transferred from the heat generating body side to the heat radiating side (see, for example, international publication No. WO 2017/115771).

However, in the heat pipe as described above, the internal space of the container is partitioned by the wick structure, and the flow path of the vapor is narrowed. Therefore, there is a problem that heat transfer efficiency is lowered. In addition, when the heat pipe is thinned, the area of the side surface portion of the core structure is reduced. Therefore, the working medium is less likely to evaporate, and the heat transfer efficiency may be reduced.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a thin heat pipe with high heat transfer efficiency.

An exemplary heat pipe of the present invention includes a tubular container having an internal space for accommodating a working medium and a porous wick structure for transporting the working medium. The container includes a bottom wall portion and an upper wall portion that are vertically opposed to each other in a cross section perpendicular to an extending direction of the container. The side wall portion connects both side end portions of the bottom wall portion and both side end portions of the upper wall portion, respectively. The core structure has a lower core structure and a pair of side core structures. The lower core structure is formed in contact with the bottom wall portion, and the upper surface thereof is disposed facing the internal space. The side core structures extend upward from both ends of the lower core structure along the side wall portions.

In the above embodiment, the upper end portion of the side core structure is formed to be separated radially inward from the side wall portion.

In the above embodiment, the core structure includes the upper core structure extending radially inward from the upper end of the side core structure along the lower surface of the upper wall.

In the above embodiment, the upper surface of the lower core structure is formed to be upwardly convex.

According to the exemplary embodiment of the present invention, a heat pipe with a reduced thickness and high heat transfer efficiency can be provided.

The foregoing and other features, elements, steps, features and advantages of the utility model will be apparent from the following more particular description of preferred embodiments of the utility model, as illustrated in the accompanying drawings.

Drawings

Fig. 1 is a sectional view showing a schematic configuration of a heat pipe according to an exemplary embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing a heat pipe of an exemplary embodiment of the present invention.

Fig. 3 is an explanatory view for explaining a method of manufacturing a heat pipe according to an exemplary embodiment of the present invention.

Fig. 4 is a cross-sectional view schematically illustrating a heat pipe according to an exemplary embodiment of the present invention.

Fig. 5 is an explanatory view for explaining a method of manufacturing a heat pipe according to an exemplary embodiment of the present invention.

Detailed Description

Hereinafter, the heat pipe 1 as a heat conduction member according to an exemplary embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, XYZ coordinates are appropriately expressed as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction represents the vertical direction (i.e., the vertical direction), + Z direction is the upward direction (the opposite side to the direction of gravity), and-Z direction is the downward direction (the direction of gravity). The Z-axis direction is also a facing direction of the bottom wall 11 and the upper wall 12, which will be described later. The X-axis direction is a direction orthogonal to the Z-axis direction, and one direction and the opposite direction are the + X direction and the-X direction, respectively. The Y-axis direction is a direction orthogonal to both the Z-axis direction and the X-axis direction, and one direction and the opposite direction are the + Y direction and the-Y direction, respectively.

< first embodiment >

(1. Structure of Heat pipe)

Fig. 1 is a sectional view showing a schematic configuration of a heat pipe 1 according to an embodiment, and fig. 2 is a sectional view schematically showing the heat pipe 1. Fig. 2 shows a cross section of the heat pipe 1 perpendicular to the extending direction (X-axis direction), which is the extending direction. The heat pipe 1 is a heat conduction member that transports heat of the heating element H. Examples of the heating element H include an electronic component that generates heat and a substrate on which the electronic component is mounted. The heat generating body H is cooled by the heat pipe 1 for heat transfer. The heat pipe 1 is mounted on an electronic device having a heat generating body H, such as a smartphone or a notebook computer.

The heat pipe 1 includes a heated portion 101 and a heat radiating portion 102. The heated portion 101 is disposed in contact with the heating element H, for example, and is heated by heat generated by the heating element H. The heat radiating section 102 radiates heat of the working medium 30, which will be described later, heated by the heated section 101 to the outside. In order to improve heat dissipation, a heat exchange unit (not shown) such as a heat sink or a radiator is thermally connected to the heat dissipation portion 102.

The heat pipe 1 includes a container 10, a working medium 30, and a core structure 20. The heated portion 101 is formed by a part of the container 10. The heat sink 102 is formed from another portion of the container 10.

(2. Structure of Container)

The container 10 is formed in a flat tubular shape and is made of metal such as copper. The container 10 may be formed of a metal other than copper. The container 10 may be formed by plating the inner peripheral surface with copper and combining it with another metal. Examples of metals other than copper include stainless steel.

The container 10 has a bottom wall 11, an upper wall 12, and a pair of side walls 13. The bottom wall 11 and the upper wall 12 are flat and arranged to face each other in the Z-axis direction. That is, the container 10 includes a bottom wall portion 11 and an upper wall portion 12 that are opposed to each other in the vertical direction (Z-axis direction) in a cross section perpendicular to the extending direction (X-axis direction), and a pair of side wall portions 13 that connect both side end portions of the bottom wall portion 11 and both side end portions of the upper wall portion 12, respectively.

The heating element H (see fig. 1) is in contact with the lower surface of the bottom wall 11. By forming the bottom wall 11 in a flat shape, the contact area between the lower surface of the bottom wall 11 and the heating element H can be increased. Therefore, the heat generated by the heating element H is efficiently transmitted to the bottom wall portion 11. The shape of the bottom wall 11 may be changed according to the shape of the heating element H.

The side wall portion 13 connects both side end portions of the upper wall portion 12 and both side end portions of the bottom wall portion 11, respectively. The upper end and the lower end of the side wall 13 are formed to be convexly curved outward in the radial direction. The thickness of the container 10 in the Z-axis direction is, for example, 1mm to 3 mm.

The container 10 has an internal space 10a surrounded by a bottom wall portion 11, an upper wall portion 12, and a side wall portion 13. The working medium 30 and the core structure 20 are disposed in the internal space 10 a. The liquefied working medium 30 moves in the porous core structure 20. The vaporized working medium 30 moves in the internal space 10 a. That is, the tubular container 10 accommodates the working medium 30 and the porous core structure 20 that transports the working medium 30 in the internal space 10 a.

The internal space 10a is a closed space and is maintained in a negative pressure state, for example, in which the air pressure is lower than the atmospheric pressure. Since the internal space 10a is in a negative pressure state, the working medium 30 accommodated in the internal space 10a is easily evaporated. The working medium 30 is, for example, water, but may be other liquid such as alcohol. The core structure 20 is made of a porous sintered copper body that transports the working medium 30.

(3. Structure of core Structure)

The core structure 20 is porous and has a void (not shown) that forms a flow path for the working medium 30. The core structure 20 extends in the extending direction (X-axis direction) of the container 10. The thickness of the core structure 20 in the radial direction from the inner peripheral surface of the container 10 is 0.02mm to 0.1 mm.

The core structure 20 is formed with a uniform thickness from the inner surface of the bottom wall portion 11 across the inner surface of the side wall portion 13, and has a lower core structure 21 and a pair of side core structures 23. The lower core structure 21 is formed in contact with the bottom wall 11 and is disposed such that the upper surface thereof faces the internal space 10 a. The side core structures 23 extend upward from both side ends of the bottom wall 11 along the side walls 13. In the present specification, "face" the internal space 10a means "face to face" with the internal space 10 a.

The lower core structure 21 has a vaporization surface 21a of the working medium 30 formed on the upper surface. The vaporizing surface 21a is disposed facing the internal space 10a, and the area of the vaporizing surface 21a does not change even when the container 10 is thinned in the Z-axis direction. Therefore, the heat pipe 1 can be thinned, and the decrease in heat transfer efficiency can be reduced.

Further, the lower core structure 21 does not contact the upper wall portion 12, and the vapor flow path in the internal space 10a is not blocked by the core structure 20.

The side core structure 23 is in contact with the inner surface of the side wall portion 13, and reinforces the side wall portion 13. This makes it difficult for the side wall 13 to bend when pressed in the Z-axis direction. Therefore, deformation of the container 10 can be prevented. This can prevent the steam flow path in the internal space 10a from being narrowed, which can reduce the heat transfer efficiency.

The upper end 23a of the side core structure 23 is formed to be radially inwardly spaced from the side wall 13. When the upper wall portion 12 of the container 10 is pressed downward and the side wall portion 13 is bent outward in a convex shape, the upper inner surface of the side wall portion 13 is supported in contact with the upper end portion 23 a. This ensures a vapor flow path, and reduces a decrease in heat transfer efficiency.

The core structure 20 is formed by, for example, applying a metal powder 40 (see fig. 3) containing fine copper particles, a copper body, and a resin to the inner circumferential surface of the container 10 by blowing, and then firing. In the present specification, "coating" means that the metal powder 40 is attached to the inner peripheral surface of the container 10. In addition to the blow coating method, the metal powder 40 may be directly coated. Further, a plug may be inserted into the container 10, and the metal powder 40 may be filled into a gap formed between the outer peripheral surface of the plug and the inner peripheral surface of the container 10. At this time, the metal powder 40 can be attached to the inner peripheral surface of the container 10 by pulling out the mandrel from the container 10 after the metal powder 40 is filled.

The fine copper particles are particles in which a plurality of copper atoms are aggregated or bonded. The particle diameter of the fine copper particles is 1 μm or more and less than 1 mm. The fine copper particles are porous, for example.

The copper body is a molten copper body obtained by sintering, melting and solidifying submicron copper particles smaller than the fine copper particles. The submicron copper particle is a particle in which a plurality of copper atoms are aggregated or bonded. The submicron copper particles before melting have a particle diameter of 0.1 μm or more and less than 1 μm.

The resin is a volatile resin that volatilizes at a temperature not higher than the melting point of copper constituting the fine copper particles and the copper bodies. Examples of the volatile resin include cellulose resins such as methyl cellulose and ethyl cellulose, acrylate resins, butyral resins, alkyd resins, epoxy resins, and phenol resins. Among them, an acrylic resin having high thermal decomposition property is preferably used.

(4. method for manufacturing Heat pipe)

Fig. 3 is an explanatory diagram for explaining a method of manufacturing the heat pipe 1. The method for manufacturing the heat pipe 1 includes a coating step, a metal powder heating step, a container pressing step, and a sealing step.

(4-1. coating Process)

In the coating step, the metal powder 40 is applied by blowing to a predetermined range in the circumferential direction of the lower portion of the inner peripheral surface of the container 10 having a circular tube shape with a uniform thickness of 0.02mm to 0.1mm (see fig. 3). The metal powder 40 includes metal particles and a volatile resin. The metal particles include a plurality of micro copper particles and a plurality of sub-micro copper particles.

(4-2. Metal powder heating Process)

In the metal powder heating step, the metal powder 40 applied in the application step is placed in a heating furnace together with the container 10 and heated. The heating temperature in this case is, for example, 400 ℃ and the heating time is, for example, 1 hour. By heating the metal powder 40, the resin contained in the metal powder 40 is volatilized, and the submicron copper particles are melted and sintered by sintering. Thereby, the porous core structure 20 is formed on the inner peripheral surface of the container 10.

(4-3. Container punching Process)

In the container pressing step, the central portion in the circumferential direction of the core structure 20 is arranged downward in the metal powder heating step, and pressing is performed while sandwiching the container 10 from the Z-axis direction (vertical direction). Thus, the container 10 is formed flat in a cross section perpendicular to the extending direction, and includes a bottom wall 11, an upper wall 12, and a side wall 13. The upper end portion 23a of the side core structure 23 is formed so as to be separated from the side wall portion 13 without following the bending of the side wall portion 13 when the container 10 is pressed (see fig. 2). Therefore, the upper end portion 23a separated radially inward from the side wall portion 13 can be easily formed.

(4-4. sealing Process)

In the sealing step, the core structure 20 inside the container 10 is sealed together with the working medium 30. Thereby, the heat pipe 1 is completed.

(5. action of Heat pipe)

In the heat pipe 1 having the above-described configuration, the heated portion 101 is heated by the heat generated by the heating element H. When the temperature of the heated portion 101 increases, the working medium 30 accommodated in the internal space 10a of the container 10 is vaporized. The vaporized vapor moves toward the heat radiating portion 102 side in the internal space 10 a. The heat dissipation section 102 dissipates heat, thereby cooling the vapor and liquefying the vapor. The liquefied working medium 30 moves toward the heated portion 101 in the core structure 20 by the capillary phenomenon. In fig. 1, the flow of vapor generated by vaporizing the working medium 30 is indicated by black arrows, and the flow of the liquid working medium 30 is indicated by hollow arrows. As described above, the working medium 30 moves with a change in state, and heat is continuously transferred from the heated portion 101 side to the heat radiating portion 102 side.

Next, another embodiment of the present invention will be explained. Fig. 4 is a sectional view schematically showing a heat pipe 1 of a second embodiment. For convenience of explanation, the same components as those of the first embodiment shown in fig. 1 to 3 are denoted by the same reference numerals. In the second embodiment, the shape of the core structure 20 is different from that of the first embodiment. The other portions are the same as those of the first embodiment.

The core structure 20 has an upper core structure 22. The upper core structure 22 extends radially inward from the upper end of the side core structure 23 along the lower surface of the upper wall 12. By forming the upper core structure 22, the surface area of the entire core structure 20 is increased, and vaporization of the working medium 30 can be promoted, thereby improving heat transfer efficiency. In addition, by forming the upper core structure 22, the contact area between the side core structure 23 and the inner surface of the side wall 13 is increased, and the side wall 13 is further reinforced. This makes it more difficult for the side wall portion 13 to bend against the pressing in the Z-axis direction.

The upper surface of lower core structure 21 is formed to be convex upward, and is formed to increase in thickness toward the Y-axis direction center portion. This increases the porosity of the core structure 20 at the center portion of the lower core structure 21 in the Y axis direction, and the working medium 30 smoothly flows through the core structure 20. Thus, by disposing the heating element H so as to face the Y-axis direction central portion of the lower core structure 21 in the Z-axis direction, the heat transport efficiency of the working medium 30 can be improved.

Fig. 5 is an explanatory view for explaining a method of manufacturing the heat pipe 1, and the metal powder 40 is formed so that the thickness in the radial direction increases toward the lower end of the container 10 in the coating step. Thus, in the container pressing step, pressing is performed with the container 10 sandwiched from the Z-axis direction (vertical direction), so that the upper surface of the bottom wall portion 11 formed as the lower core structure 21 is easily formed to be convex upward. In addition, lower core structure 21 is formed to have a thickness that increases toward the Y-axis direction center portion.

While the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications can be added without departing from the spirit of the present invention. The above embodiments and modifications thereof can be combined as appropriate.

The heat pipe of the present invention can be used as a substrate mounted on an electronic device or a member for dissipating heat from an electronic element, for example.

Claims

1. A heat pipe comprising a tubular container having an internal space for accommodating a working medium and a porous wick structure for transporting the working medium,

the container comprises:

a bottom wall portion and an upper wall portion that are vertically opposed to each other in a cross section perpendicular to an extending direction that is an extending direction of the container; and

a pair of side wall parts respectively connecting both side end parts of the bottom wall part and both side end parts of the upper wall part,

it is characterized in that the preparation method is characterized in that,

the core structure includes:

a lower core structure formed in contact with the bottom wall portion and having an upper surface disposed to face the internal space; and

and a pair of side core structures extending upward from both ends of the lower core structure along the side wall portions.

2. A heat pipe according to claim 1,

the upper end portion of the side core structure is formed to be separated radially inward from the side wall portion.

3. A heat pipe according to claim 1,

the core structure includes an upper core structure extending radially inward from an upper end of the side core structure along a lower surface of the upper wall.

4. A heat pipe according to any one of claims 1 to 3,

the upper surface of the lower core structure is formed to be upwardly convex.