JP2023127010A - Heat conductive member - Google Patents

Abstract

To provide a heat conductive member that has improved efficiency of heat transport by vaporization of working fluid in a porous sheet on a heat generating side and condensation of the working fluid in the porous sheet on a heat radiation surface side.SOLUTION: A housing 10 includes a first metal plate 11 and a second metal plate 12. The second metal plate 12 is disposed opposed to the first metal plate 11. A heating element H is disposed on the external surface of the second metal plate. A pillar part is disposed between the first metal plate 11 and the second metal plate 12. A working medium 20, a first wick structure 31, and a second wick structure 32 are stored in an internal space 10a. The first wick structure 31 is disposed on the inner surface of the first metal plate 11. The second wick structure 32 is disposed on the inner surface of the second metal plate 12. The second wick structure 32 includes a convex part 32a protruding in a vertical direction from the inner surface, and at least part of the convex part is positioned in a first region U1 that overlaps with the heating element H in a vertical direction of the first metal plate 11 and the second metal plate 12.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to thermally conductive members.

A conventional heat conductive member includes a flat closed container, a porous sheet, and a working fluid. The porous sheet is placed on the inner surface of the flat sealed container. The working fluid is contained inside the flat sealed container.

The flat closed container is placed in contact with the heating element. A porous sheet is disposed on the inner surface of the flat sealed container on the side of the heating element and on the inner surface of the flat sealed container on the side of the heat radiation surface which is opposite to the side of the heating element. The working fluid is heated by the heating element and vaporized from the porous sheet on the heating side. The vaporized working fluid condenses on the porous sheet on the heat radiation surface side. As a result, heat is transported from the heating element side to the heat radiation surface side (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2002-62072

However, the heat conducting member as described above has a problem in that the working fluid in the vicinity of the heating element is less likely to evaporate, resulting in low heat transport efficiency.

The present disclosure aims to provide a heat conductive member that can improve heat transport efficiency.

An exemplary heat-conducting member of the present disclosure includes a housing having an internal space, a first wick structure, a second wick structure, a working medium, and a column. The housing includes a first metal plate and a second metal plate. The second metal plate is disposed opposite to the first metal plate, and a heating element is disposed on the outer surface of the second metal plate. The pillar portion is arranged between the first metal plate and the second metal plate. The working medium, the first wick structure, and the second wick structure are housed in the internal space. The first wick structure is arranged on the inner surface of the first metal plate. The second wick structure is arranged on the inner surface of the second metal plate. The second wick structure has a convex portion vertically protruding from the inner surface, and at least a portion of the convex portion is located in a first region of the first metal plate and the second metal plate overlapping the heating element in the vertical direction. do.

According to the present disclosure, it is possible to provide a heat conductive member in which evaporation of the working fluid near the heating element is likely to occur and the heat transport efficiency can be improved.

FIG. 1 is a perspective view of a heat conductive member according to this embodiment. FIG. 2 is a schematic side sectional view of the heat conductive member according to this embodiment. FIG. 3 is a schematic side sectional view of a heat conductive member according to a modification of the present embodiment.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. In addition, in the drawings, an XYZ coordinate system is shown as a three-dimensional orthogonal coordinate system as appropriate. In the XYZ coordinate system, the Z-axis direction indicates the vertical direction (that is, the up-down direction), the +Z direction is the upper side (opposite to the direction of gravity), and the -Z direction is the lower side (the direction of gravity). The Z-axis direction is also the vertical direction of the first metal plate 11 and the second metal plate 12, which will be described later. The X-axis direction refers to a direction perpendicular to the Z-axis direction, and one direction and the opposite direction are defined as the +X direction and the −X direction, respectively. The Y-axis direction refers to a direction perpendicular to both the Z-axis direction and the X-axis direction, and one direction and the opposite direction are defined as the +Y direction and the −Y direction, respectively. However, this direction is defined only for convenience of explanation, and does not limit the orientation during manufacture and use of the heat conductive member 1 according to the present disclosure. In addition, when expressed as parallel in this application, it does not refer only to the case where the objects are strictly parallel mathematically, but also includes the case where the objects are parallel to the extent that the effects of the present disclosure are achieved, for example.

Further, in this specification, "sintering" refers to a technique of heating metal powder or metal powder to a temperature lower than the melting point of the metal to sinter and solidify the metal particles. Furthermore, the term "sintered body" refers to an object obtained by sintering.

<1. Configuration of heat conductive member>
FIG. 1 is a perspective view of a heat conductive member 1 according to an exemplary embodiment of the present disclosure (hereinafter referred to as the present embodiment), and FIG. 2 is a schematic side sectional view of the heat conductive member 1. The heat conductive member 1 is also called a vapor chamber, and transports the heat of the heating element H. Examples of the heating element H include a power transistor of an inverter included in a traction motor for driving wheels of a vehicle. The power transistor is, for example, an IGBT (Insulated Gate Bipolar Transistor). In this case, the heat conductive member 1 is mounted on a traction motor. The calorific value of an IGBT is generally 100W or more.

A heating element H is placed in contact with the lower surface of the thermally conductive member 1 . The heat generated by the heating element H is radiated from the upper surface of the heat conductive member 1. In addition, in order to improve heat dissipation performance, heat dissipation fins such as stacked fins and pin fins may be provided on the upper surface of the heat conductive member 1. In that case, a cooling medium is flowed between the heat radiation fins. The cooling medium may be water, oil, or air, for example.

In addition, in the structure shown in FIG. 1 and FIG. 2, one heating element H is arrange|positioned at the center part of the lower surface of the rectangular-shaped heat conductive member 1 as an example. However, the heating element H may be arranged at the lower edge of the heat conductive member 1. Further, a plurality of heating elements H may be arranged on the lower surface of the heat conductive member 1.

The thermally conductive member 1 includes a housing 10 , a working medium 20 , a column 15 , a first wick structure 31 , a second wick structure 32 , and a third wick structure 33 . The column portion includes at least one of the first column portion 15 and the second column portion 33. The thickness of the heat conductive member 1 in the Z direction is, for example, 5 mm or more.

<1-1. Housing configuration>
The housing 10 has an internal space 10a. The column portion 15, the working medium 20, the first wick structure 31, and the second wick structure 32 are arranged in the internal space 10a. The casing 10 includes a first metal plate 11 and a second metal plate 12 that is disposed opposite to the first metal plate 11 and has a heating element H disposed on its outer surface. The column portion 15 is arranged between the first metal plate 11 and the second metal plate 12. The column portion 15 is arranged in the internal space 10a and supports the first metal plate 11 and the second metal plate 12. As the first metal plate 11 and the second metal plate 12, for example, a metal with high thermal conductivity such as copper is used. Alternatively, the surface of a metal other than copper may be plated with copper. For example, stainless steel can be considered as a metal other than copper.

The first metal plate 11 and the second metal plate 12 are made of a highly thermally conductive metal such as copper, for example. Alternatively, the surface of a metal other than copper may be plated with copper. For example, stainless steel can be considered as a metal other than copper.

The first metal plate 11 and the second metal plate 12 are rectangular plates that extend in the horizontal direction when viewed from above. A heating element H is placed in contact with the outer surface of the second metal plate 12 . The first metal plate 11 covers the upper surface of the second metal plate 12. Note that although the first metal plate 11 and the second metal plate 12 of this embodiment are square in top view, the shape is not limited to this. For example, it may be a polygon having a plurality of corners when viewed from above, or a circle.

The first metal plate 11 has a first side wall portion 13a extending downward from the periphery. The second metal plate 12 has a second side wall portion 13b extending upward from the periphery. The lower surface of the first side wall portion 13a and the upper surface of the second side wall portion 13b are joined at a joint portion 14. Note that the second side wall portion 13b may be omitted and the lower surface of the first side wall portion 13a and the upper surface of the second metal plate 12 may be joined. Alternatively, the first side wall portion 13a may be omitted, and the upper surface of the second side wall portion 13b and the lower surface of the first metal plate 11 may be joined.

The internal space 10a is surrounded by a first metal plate 11 and a second metal plate 12. The internal space 10a is a closed space, and is maintained in a reduced pressure state, for example, where the pressure is lower than atmospheric pressure. Since the internal space 10a is in a reduced pressure state, the working medium 20 accommodated in the internal space 10a easily evaporates. The working medium 20 is, for example, water, but may also be other liquids such as alcohol.

The joint portion 14 is located around the first wick structure 31 and the second wick structure 32 when viewed from above. The method of joining the first side wall portion 13a and the second side wall portion 13b is not particularly limited. For example, any joining method may be used, such as joining by applying heat and pressure, diffusion joining, or joining using a brazing material.

Note that the joint portion 14 may include a sealing portion. The sealing portion is, for example, a location where an injection port for injecting the working medium 20 into the housing 10 is sealed by welding during the manufacturing process of the heat conductive member 1.

In this embodiment, the column part 15 is a separate member from the first metal plate 11 and the second metal plate 12, and is arranged between the first metal plate 11 and the second metal plate 12 in the internal space 10a, This is a member that supports the first metal plate 11 and the second metal plate 12. The column portion 15 has, for example, a circular cylindrical shape when viewed from above. The pillar portions 15 are two-dimensionally and regularly aligned in the XY plane. The thickness of the casing 10 in the Z-axis direction is kept constant by the pillar portion 15 directly or indirectly supporting the first metal plate 11 and the second metal plate 12 in the Z-axis direction. Thereby, it is possible to suppress the inner space 10a from becoming narrower due to deformation of the housing 10 in the Z-axis direction.

In this embodiment, at least a portion of the column 15 includes a first column 16 that is a solid member. The first column part 16 is arranged between the first metal plate 11 and the second metal plate 12 in the internal space 10a, and supports the first metal plate 11 and the second metal plate 12. Thereby, deformation of the housing 10 in the Z-axis direction is suppressed, and narrowing of the internal space 10a can be suppressed. Note that a "solid" member means a so-called solid member, and refers to a member that is densely packed and made of a non-porous material. For example, a "solid" member may be a member that has no internal cavity, or may be a member that has one or more macroscopic cavities within it. Note that as the solid member, for example, a metal with high thermal conductivity such as copper is used.

In this embodiment, at least a portion of the columnar portion 15 includes a second columnar portion 33 that is a porous sintered body. Here, the second column portion 33 is the third wick structure 33. The third wick structure 33 is disposed between the first wick structure 31 and the second wick structure 32 in the internal space 10a, and supports the first wick structure 31 and the second wick structure 32. The third wick structure 33 supports the first metal plate 11 and the second metal plate 12 via the first wick structure 31 and the second wick structure 32. Thereby, deformation of the housing 10 in the Z-axis direction can be further suppressed, and narrowing of the internal space 10a can be suppressed.

That is, in this embodiment, the columnar section 15 each has a first columnar section 16 that is a solid member and a second columnar section 33 that is a porous sintered body. As described above, the second column portion 33 is the third wick structure 33. Hereinafter, the second pillar portion 33 will be described as a third wick structure 33. It is preferable that the third wick structure 33 is arranged between adjacent first column parts 16.

Among the pillar parts 15, the first pillar part 16, which is a solid member, extends in the Z-axis direction, and the upper and lower ends of the first pillar part are connected to the lower surface of the first metal plate 11 and the second metal plate. 12 using brazing filler metal. Note that the first column portion 16 may be joined to the first metal plate 11 and the second metal plate 12 by welding or the like instead of joining using a brazing material. Note that the first column portion 16 may be integrated with one of the first metal plate 11 and the second metal plate 12. At this time, the first column part 16 can be formed by etching or cutting the first metal plate 11 or the second metal plate 12.

<1-2. Configurations of the first wick structure, second wick structure, and third wick structure>
The first wick structure 31 , the second wick structure 32 , and the third wick structure 33 are porous and have voids (not shown) that form flow paths for the working medium 20 .

The first wick structure 31 is a plate-shaped member arranged on the inner surface of the first metal plate 11, and is arranged on the cooling side opposite to the heating element H side. The second wick structure 32 is a plate-shaped member arranged on the inner surface of the second metal plate 12, and is arranged on the heating element H side. The first wick structure 31 and the second wick structure 32 are arranged to face each other. A vapor space S is formed between the first wick structure 31 and the second wick structure 32. The vapor space S is a space for diffusing the vapor of the working medium 20.

The third wick structure 33 is disposed within the internal space 10a and connects the first wick structure 31 and the second wick structure 32. The third wick structure 33 extends in the Z-axis direction and is configured, for example, as a circular column when viewed from above. Further, the third wick structures 33 are two-dimensionally and regularly aligned in the XY plane. It is preferable that the third wick structure 33 is arranged between adjacent first column parts 16.

The third wick structure 33 supports the first metal plate 11 and the second metal plate 12 via the first wick structure 31 and the second wick structure 32. Thereby, the third wick structure 33 can reinforce the first pillar portion 16 and further suppress deformation of the housing 10 in the Z-axis direction.

Further, the first wick structure 31, the second wick structure 32, and the third wick structure 33 are each a porous sintered body and are integral. By making the first wick structure 31, the second wick structure 32, and the third wick structure 33 a porous sintered body, they can be manufactured more easily than mesh materials, and the manufacturing cost of the heat conductive member 1 is reduced. can be lowered. Further, by providing the third wick structure 33, the number of flow paths for the working medium 20 from the first wick structure 31 to the second wick structure 32 can be increased.

Here, the working medium 20 vaporized from the second wick structure 32 on the side of the heating element H is condensed in the first wick structure 31 disposed on the side of the heat radiation surface opposite to the heating element H. In other words, the first wick structure 31 can further promote condensation of the working medium 20. In other words, the first wick structure 31 disposed on the heat radiation surface side opposite to the heating element H promotes condensation of the vaporized working medium 20 more than the second wick structure 32. Therefore, it is preferable that the first wick structure 31 has a higher cooling efficiency for the working medium 20 than the second wick structure 32.

Further, the second wick structure has a convex portion 32a that protrudes from the inner surface in the vertical direction.
At least a portion of the convex portion 32a is located in a first region U1 that overlaps the heating element H in the vertical direction of the first metal plate 11 and the second metal plate 12.

At this time, the thickness W2a of the second wick structure 32 at the convex portion 32a is formed to be larger than the thickness W2b of the second wick structure 32 in the area other than the convex portion 32a. By increasing the thickness of the second wick structure 32, the working medium can be reduced in at least a portion of the first region U1 that overlaps with the heating element H in the Z direction (the direction in which the first metal plate 11 and the second metal plate 12 face each other). The evaporation of 20 is accelerated. Thereby, the efficiency of heat transport by the working medium 20 can be improved.

Normally, condensation of the working medium 20 is most promoted in the first region U1 facing the heating element H in the Z direction. Here, by increasing the thickness of the wick structure, it is possible to contain a large amount of the condensed working medium 20. That is, by providing the convex portion 32a on the second wick structure 32 in the first region U1 as in the present embodiment, retention of the condensed working medium 20 in the vicinity of the heating element H can be improved. Thereby, sufficient working medium 20 is supplied in the first region U1, and evaporation of working medium 20 can be further promoted. Therefore, the heat generated by the evaporation of the working medium 20 can be efficiently radiated to the heat radiation surface side throughout the first metal plate 11. Thereby, the efficiency of heat transport by the working medium 20 can be improved.

In this embodiment, the upper surface of the convex portion 32a is formed in a plane parallel to the second metal plate 12, but it may be formed in a mountain shape. That is, the thickness W2a of the second wick structure 32 at the convex portion 32a is gradually increased toward a predetermined position within the first region U1. This makes it easier to evaporate at a predetermined position within the first region U1.

Further, the entire convex portion 32a does not need to overlap the first region U1 in the Z direction. In this case, the end of the convex portion 32a may overlap the second region U2 in the Z direction. Even in this case, by increasing the thickness of the second wick structure near the heating element H, the retention of the working medium 20 condensed near the heating element H can be improved. Sufficient working medium 20 is supplied near the heating element H, and evaporation of working medium 20 can be further promoted. Thereby, the heat generated by the evaporation of the working medium 20 can be efficiently radiated to the heat radiation surface side by the entire first metal plate 11. Thereby, the efficiency of heat transport by the working medium 20 can be improved.

The convex portion 32a of the second wick structure 32 has a larger area than the first region U1 in plan view, and the convex portion 32a overlaps the entire area of the first region U1 in the vertical direction.

By providing the convex portion 32a on the second wick structure 32 throughout the first region U1, the ability to retain the condensed working medium 20 near the heating element H can be further improved. Thereby, sufficient working medium 20 is supplied throughout the first region U1, and evaporation of working medium 20 can be further promoted. Therefore, the heat generated by the evaporation of the working medium 20 can be efficiently radiated to the heat radiation surface side throughout the first metal plate 11. Thereby, the efficiency of heat transport by the working medium 20 can be improved.

Further, the thickness W2a of the second wick structure 32 at the convex portion 32a of the first region U1 is larger than the thickness W1 of the first wick structure 31 in the Z direction. The second wick structure 32 disposed on the heating element H side accelerates the vaporization of the liquid working medium 20 more than the first wick structure 31. By making the thickness W2a of the second wick structure 32 at the convex portion 32a of the first region U1 larger in the Z direction than the thickness W1 of the first wick structure 31, the second wick structure 32 can hold the working medium 20. The holding capacity of the working medium 20 of the first wick structure 31 can be made higher than that of the first wick structure 31. Note that the average thickness of the second wick structure 32 is preferably larger than the average thickness of the first wick structure 31. This further improves the ability of the second wick structure 32 to hold the working medium.

Furthermore, the ability of the second wick structure 32 to retain the working medium 20 is improved, so that the liquid working medium 20 held by the second wick structure 32 is improved in the first region U1 overlapping with the heating element H in the Z direction. It is possible to suppress the occurrence of so-called dry-out, in which the water completely evaporates.

Further, in the Z direction (the vertical direction of the first metal plate 11 and the second metal plate 12), the thickness W1 of the first wick structure 31 in the first region U1, the thickness W2a of the second wick structure 32, and the thickness W2a of the second wick structure 32 are It is preferable that the length W3 of the gap between the first wick structure 31 and the second wick structure 32 satisfies Expression (1).

W3>W2a+W1...(1)

By providing a large gap in the Z direction between the first wick structure 31 and the second wick structure 32 in the internal space 10a, the working medium 20 vaporized from the second wick structure 32 can be moved in the XY direction within the internal space 10a. It becomes easier to diffuse within the plane. This promotes condensation of the working medium 20 in the first wick structure 31. Note that the same effect can be obtained by applying the thickness W2b of the first wick structure 32 in the second region U2 to equation (1) instead of the thickness W2a of the second wick structure 32 in the first region U1.

Further, in the first region U1, the thickness W1 of the first wick structure 31 and the thickness W of the second wick structure 32 in the Z direction (vertical direction of the first metal plate 11 and the second metal plate 12)
2a and the length W3 of the gap between the first wick structure 31 and the second wick structure 32 more preferably satisfy Expressions (2) to (4).

4W1≧W2a≧2W1...(2)
7W1≧W3≧5W1...(3)
W3+W2a=9W1...(4)

That is, the thickness W2a of the second wick structure 32 is set to be at least 2 times and at most 4 times the thickness W1 of the first wick structure 31 in the first region U1, so that the thickness W2a of the second wick structure 32 is It is preferable that the length W3 of the gap is 5 times or more and 7 times or less the thickness W1 of the first wick structure 31 in the first region U1. Thereby, condensation of the working medium 20 in the first wick structure 31 can be further promoted while ensuring the ability of the second wick structure 32 to retain the working medium 20. Note that the same effect can be obtained by applying the thickness W2b of the second wick structure 32 in the second region U2 to equations (2) to (4) instead of the thickness W2a of the second wick structure 32 in the first region U1. is obtained.

Further, the second wick structure 32 has a higher porosity than the first wick structure 31. Thereby, the capillary force of the second wick structure 32 becomes larger than the capillary force of the first wick structure 31.

Here, the ratio of the volume of the space to the total volume of the first wick structure 31 and the second wick structure 32 is called porosity. The unit of porosity is %. The porosity is determined by the following method. For example, the porosity can be determined by measuring the area of the space from a cross-sectional photograph of the wick structure and calculating the ratio of the area of the space to the whole. In observing the cross sections of the first wick structure 31 and the second wick structure 32, it is preferable to use a scanning electron microscope with a deep depth of field. Note that the method for observing the cross section is not particularly limited as long as it can easily distinguish between metal parts and spaces.

In this embodiment, the first wick structure 31 and the second wick structure 32 are made of porous sintered bodies, but the first wick structure 31 or the second wick structure 32 is made of a plurality of porous sintered bodies. It may also be a mesh member in which metal wire members are woven. By constructing the second wick structure 32 with a mesh material and constructing the first wick structure 31 with a porous sintered body, the capillary force of the second wick structure 32 is absorbed by the first wick structure 31. It is larger than capillary force and can be easily formed.

Further, the first wick structure 31 or the second wick structure 32 may be constituted by a plurality of grooves formed on the inner surface of the first metal plate 11 and the inner surface of the second metal plate 12. Thereby, the first wick structure 31 or the second wick structure 32 can be formed thinner than when constructed from a mesh material and a sintered body. Therefore, the internal space 10a can be expanded in the Z-axis direction. Further, the casing 10 can be made thinner in the Z-axis direction without narrowing the internal space 10a. Furthermore, by configuring either the first wick structure 31 or the second wick structure 32 with a groove, the thickness of the first wick structure 31 or the second wick structure 32 in the Z-axis direction can be reduced without narrowing the internal space 10a. can be made larger.

The first wick structure 31, the second wick structure 32, and the third wick structure 33 are formed, for example, as follows. First, a mixed powder containing micro copper particles, a copper body, and a resin is spray coated on the lower surface of the first metal plate 11 and the upper surface of the second metal plate 12 before being bonded. Next, the first metal plate 11 and the second metal plate 12 are joined with the mixed powder formed into a columnar shape sandwiched therebetween. Thereafter, the casing 10 is heated to bake the mixed powder. Thereby, the first wick structure 31, the second wick structure 32, and the third wick structure 33 can be easily formed integrally in the internal space 10a of the housing 10. Thereby, the manufacturing cost of the heat conductive member 1 can be suppressed. Note that the first metal plate 11 and the second metal plate 12 may be joined after the first wick structure 31, the second wick structure 32, and the third wick structure 33 are fired separately.

Note that in this specification, "coating" refers to attaching the mixed powder to the lower surface of the first metal plate 11 and the second metal plate 12. In addition to spray coating, a paste containing mixed powder may be applied.

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

The copper body is a molten copper body in which sub-micro copper particles smaller than micro copper particles are melted and solidified by sintering. Sub-micro copper particles are particles in which a plurality of copper atoms are aggregated or combined. The particle size of the sub-micro copper particles before melting is 0.1 μm or more and less than 1 μm.

The resin is a volatile resin that evaporates at a temperature below the melting point of the copper that constitutes the micro copper particles and the copper body. Examples of such volatile resins include cellulose resins such as methyl cellulose and ethyl cellulose, acrylic resins, butyral resins, alkyd resins, epoxy resins, and phenol resins. Among these, it is preferable to use an acrylic resin with high thermal decomposition properties.

<2. Operation of heat conductive member>
In FIG. 2, the flow of steam generated by vaporizing the working medium 20 is shown by black arrows in the heat conduction member 1, and the flow of the liquid working medium 20 is shown by white arrows in the heat conduction member 1.

In the heat conductive member having the above configuration, when the temperature of the second metal plate 12 rises due to the heat generated by the heating element H, the liquid working medium 20 contained in the second wick structure 32 vaporizes.

The working medium 20 that has been vaporized into vapor diffuses in the vapor space S. Note that the steam space S is a space obtained by excluding the space occupied by the first column part 16 and the third wick structure 33 from the gap space between the first wick structure 31 and the second wick structure 32. .

At this time, a part of the vaporized working medium 20 comes into contact with the first wick structure 31, is cooled, and is condensed. The first wick structure 31 has a larger surface area than the lower surface of the first metal plate 11 and has higher cooling efficiency. Therefore, by providing the first wick structure 31, the cooling efficiency of the vaporized working medium 20 is improved and condensation is promoted.

A part of the working medium 20 condensed on the first wick structure 31 drips and is absorbed into the second wick structure 32 . Further, a part of the working medium 20 condensed in the first wick structure 31 moves through the first wick structure 31 and the third wick structure 33 and is absorbed into the second wick structure 32 . Further, a part of the working medium 20 condensed in the first wick structure 31 moves along the outer surface of the first column part 16 and is absorbed into the second wick structure 32 .

The condensed working medium 20 moves through the second wick structure 32 toward the first region U1 due to capillary action. Further, the working medium 20 absorbed from the first wick structure 31 to the second wick structure 32 also moves through the second wick structure 32 toward the first region U1 due to capillary action.

At this time, since the capillary force of the second wick structure 32 is higher than the capillary force of the first wick structure 31, the heating element H is arranged to collect the working medium 20 condensed through the second wick structure 32. It can be moved to the desired position more quickly. Therefore, the efficiency of heat transport by the working medium 20 is improved.

Further, the thickness W2 of the second wick structure 32 is made larger in the Z direction than the thickness W1 of the first wick structure 31, thereby suppressing the occurrence of dryout in the region facing the heating element H in the Z direction. Thereby, the liquid working medium 20 can be continuously and smoothly moved toward the first region U1 in the second wick structure 32. Therefore, a decrease in heat transport efficiency of the working medium 20 due to occurrence of dryout can be suppressed.

As the working medium 20 moves while changing its state as described above, heat is continuously transported from the heating element H side to the cooling side.

<3. About steam space＞
As mentioned above, the steam space S is the gap space between the first wick structure 31 and the second wick structure 32 excluding the space occupied by the first column part 16 and the third wick structure 33. It is space. That is, the steam space S is a space other than the first wick structure 31, the second wick structure 32, the third wick structure 33, and the first column part 16 in the internal space 10a.

In this embodiment, the following formula (5) is satisfied.
V1>V2...(5)
However, V1: Volume of steam space S, V2: Total volume

At this time, the total volume is the sum of the volumes of the first wick structure 31, the second wick structure 32, and the third wick structure 33. That is, in this embodiment, the total volume further includes the volume of the third wick structure 33 in the total volume of the first wick structure 31 and the second wick structure 32.

Note that when the third wick structure 33 is not provided, the total volume is calculated by summing the respective volumes of the first wick structure 31 and the second wick structure 32.

By doing so, the volume of the vapor space S can be secured and the diffusion of the vapor of the working medium 20 can be promoted. Therefore, the heat transport efficiency of the heat conductive member 1 can be improved.

Further, although the first column portion 16 can ensure the strength of the housing 10, its placement causes the steam space S to become narrower, and even when such a first column portion 16 is provided, the above formula ( By satisfying 5), vapor diffusion can be promoted.

Furthermore, from the above equation (5), the volume of the steam space S is larger than the sum of the volumes of the first wick structure 31, the second wick structure 32, and the third wick structure 33, so that It can promote diffusion.

<4. First pillar part and third wick structure>
In this embodiment, it is preferable that the first column part 16 and the third wick structure 33 have the following configuration.

The total bonding area where the top surface of the first column part 16 and the bottom surface of the first metal plate 11 are bonded is the bonding area where the top surface of the third wick structure 33 and the bottom surface of the first wick structure 31 are bonded. greater than the sum of In addition, the total joint area where the lower surface of the first column part 16 and the upper surface of the second metal plate 12 are joined is equal to the total joint area where the lower surface of the third wick structure 33 and the upper surface of the second wick structure 32 are joined. It is larger than the total joint area. Note that the total joint area is the sum of the joint areas for all the first column parts 16 or third wick structures 33.

However, as shown in a modified example in FIG. 3, the third wick structure 33 penetrates the first wick structure 31 and is joined to the first metal plate 11, and also penetrates the second wick structure 32 It may be joined to the second metal plate 12. In such a case, the total joint area where the upper surface of the first column part 16 and the lower surface of the first metal plate 11 are joined is the upper surface of the third wick structure 33 and the lower surface of the first metal plate 11. is larger than the total joint area to be joined. In addition, the total joint area where the lower surface of the first column part 16 and the upper surface of the second metal plate 12 are joined is equal to the total joint area where the lower surface of the third wick structure 33 and the upper surface of the second metal plate 12 are joined. greater than the sum of the areas.

That is, the total contact area where one side end of the first column part 16 is in contact with the first metal plate 11 is the total contact area where one side end of the third wick structure 33 is in contact with the first wick structure 31 or the first metal plate 11. The sum of the contact areas where the other side end of the first column part 16 is in contact with the second metal plate 12 is larger than the total contact area where the other side end of the third wick structure 33 is in contact with the second metal plate 12. It is wider than the total contact area with the wick structure 32 or the second metal plate 12.

The strength of the solid column portion 15 is higher than the strength of the third wick structure 33. Therefore, even in a configuration using the third wick structure 33, the strength of the casing 10 can be sufficiently ensured by the first pillar portion 16 due to the size relationship of the contact area as described above.

<5. Others>
The embodiments of the present disclosure have been described above. Note that the scope of the present disclosure is not limited to the above-described embodiments. The present disclosure can be implemented by adding various changes to the above-described embodiments without departing from the spirit of the invention. Moreover, the matters described in the above embodiments can be combined as appropriate and arbitrarily within a range that does not cause any contradiction.

For example, the first wick structure 31 may be made of a mesh material, and the second wick structure 32 may be made of a porous sintered body. Alternatively, at least one of the first column portion 16 and the third wick structure 33 may not be provided.

Further, the first wick structure 31 has a recess in at least a part of the first region U1 that overlaps with the heating element H in the Z direction (the vertical direction of the first metal plate 11 and the second metal plate 12). Also good. In that case, the effect is that condensation is suppressed, making it easier for vapor to diffuse.

In the embodiment of the present disclosure, it is assumed that the columnar portion 15 includes a mixture of the first columnar portion 16 and the third wick structure 33; But that's fine.

The present disclosure can be used to cool various heating elements.

1 Heat conductive member 10 Housing 10a Internal space 11 First metal plate 12 Second metal plate 13a First side wall portion 13b Second side wall portion 14 Joint portion 15 Column portion 16 First column portion 20 Working medium 31 First wick structure 32 Second wick structure 32a Convex portion 33 Second column, third wick structure H Heating element S Steam space U1 First region U2 Second region

Claims (15)

a casing having an internal space;
a first wick structure;
a second wick structure;
a working medium;
comprising a pillar part;
The casing is
a first metal plate; a second metal plate disposed opposite to the first metal plate and having a heating element disposed on the outer surface;
The pillar portion is
disposed between the first metal plate and the second metal plate,
The working medium, the first wick structure, and the second wick structure are housed in the internal space,
the first wick structure is disposed on the inner surface of the first metal plate,
the second wick structure is arranged on the inner surface of the second metal plate,
The second wick structure has a convex portion protruding from the inner surface in the vertical direction,
A heat conductive member, wherein at least a portion of the convex portion is located in a first region of the first metal plate and the second metal plate that overlaps with the heating element in the vertical direction. The pillar portion is arranged in the internal space,
a solid first pillar portion that supports the first metal plate 11 and the second metal plate 12;
The heat conductive member according to claim 1, comprising at least one of a second column part that supports the first wick structure and the second wick structure and is a porous sintered body. According to claim 1 or 2, the first wick structure is a porous sintered body.
The heat conductive member described. The heat conductive member according to any one of claims 1 to 3, wherein the second wick structure is a mesh member in which a plurality of metal wire members are woven. The heat conductive member according to any one of claims 1 to 3, wherein the second wick structure is a porous sintered body. The convex portion of the second wick structure has a larger area than the first region in plan view,
The heat conductive member according to any one of claims 1 to 5, wherein the convex portion overlaps the entire area of the first region in the vertical direction. The heat conductive member according to any one of claims 1 to 6, wherein the thickness of the second wick structure in the convex portion is gradually increased toward a predetermined position in the first region. The heat conductive member according to any one of claims 1 to 5, wherein the first wick structure, the second wick structure, and the second pillar portion are integral. The heat conductive member according to any one of claims 1 to 8, wherein the second wick structure has a higher porosity than the first wick structure. The heat conductive member according to any one of claims 1 to 9, wherein the capillary force of the second wick structure is higher than the capillary force of the first wick structure. The heat conductive member according to any one of claims 1 to 10, wherein the average thickness of the second wick structure is larger than the average thickness of the first wick structure. In the first region, the length of the gap between the first wick structure and the second wick structure in the vertical direction, the thickness of the second wick structure, and the thickness of the first wick structure. 12. The heat conductive member according to claim 11, which satisfies the following formula (1).
W3>W2a+W1...(1)
W1: Thickness of the first wick structure W2a: Thickness of the second wick structure
W3: Length of the gap between the first wick structure and the second wick structure In the first region, the length of the gap between the first wick structure and the second wick structure in the vertical direction, the thickness of the second wick structure, and the thickness of the first wick structure. 13. The heat conductive member according to claim 12, which satisfies the following formulas (2) to (4).
4W1≧W2a≧2W1...(2)
7W1≧W3≧5W1...(3)
W3+W2a=9W1...(4) a volume of a vapor space that is included in a space other than the first wick structure, the second wick structure, the first column part, and the second column part in the internal space and in which vapor of the working medium can exist; The heat conductive member according to any one of claims 1 to 13, wherein the total volume of the first wick structure and the second wick structure satisfies the following formula (5).
V1>V2...(5)
V1: Volume of a vapor space that is included in a space other than the first wick structure, the second wick structure, the first pillar part, and the second pillar part in the internal space, and in which the vapor of the working medium can exist. V2: Total volume of the first wick structure and the second wick structure The thermally conductive member according to claim 14, wherein the total volume further includes a volume of the second pillar portion.

Images