JP7426844B2 - Heat transfer member and cooling device having heat transfer member - Google Patents

Description

The present invention relates to a heat transfer member that transfers heat from a heating element to change the phase of a first refrigerant from a liquid phase to a gas phase, and a cooling device that includes this heat transfer member.

With the increasing functionality of electronic devices in recent years, heating elements such as electrical and electronic components (hereinafter simply referred to as "heating elements") are mounted in a high density inside electronic devices. The amount of heat generated tends to increase. If the temperature of the heating element rises above a predetermined allowable temperature, it may cause the heating element to malfunction, so it is necessary to keep the temperature of the heating element always below the allowable temperature. Therefore, a cooling device for cooling the heating element is usually installed inside the electronic device. As such a cooling device, for example, a boiling cooling device that utilizes latent heat (heat of vaporization) by changing the phase of a refrigerant from a liquid phase to a gas phase is known.

As described above, heating elements such as electric/electronic components that constitute electronic devices tend to generate more heat, so there is a demand for further improvement in the cooling performance of boiling cooling devices. In order to further improve the cooling performance of the evaporative cooling device, it is useful to smooth the phase change of the refrigerant from the liquid phase to the gas phase, and in particular to smooth the heating and boiling of the refrigerant.

As a means for smoothing the heating and boiling of the refrigerant, for example, Patent Document 1 discloses a method in which a refrigerant liquid is accommodated inside and heat generated from a heating element is transferred to the refrigerant liquid via a heat transfer member. As a boiling cooling device equipped with a refrigerant tank that boils the refrigerant liquid by Disclosed is an evaporative cooling device in which a convex portion protruding toward the refrigerant liquid side is formed corresponding to all the heating elements, and the convex portion is in contact with only the refrigerant liquid. ing.

Patent Document 1 assumes that the shape of isothermal flux lines of heat transferred from a heating element to a heat transfer member is a spherical surface, and describes that the surface shape of the heat transfer member may be a spherical surface, a stepped shape or a weight based on the spherical shape. It is described that by forming the heat exchanger in a shape, burnout resistance can be improved and resistance to heat transmitted from the heating element to the heat transfer surface can be suppressed.

Japanese Patent Application Publication No. 2010-016277

However, when the surface of the heat transfer member that contacts the refrigerant (boiling surface) is configured to have a spherical shape, the heat flux upward from the center of the sphere tends to become too large. Furthermore, especially when the heating element is not circular, the heat flux at the boiling surface tends to be non-uniform. Here, the relationship between heat flux and heat transfer coefficient is that while heat flux increases from 0 to maximum heat flux, the heat transfer coefficient increases as heat flux increases; It is known that the heat transfer coefficient decreases even if the heat flux increases when the temperature exceeds . Here, the heat transfer member of Patent Document 1 cannot be said to have a high heat transfer coefficient because there are parts where the heat flux is low and parts where the heat flux exceeds the maximum heat flux, and the cooling efficiency of the heat transfer member is could not be said to have been sufficiently enhanced. Therefore, in the heat transfer member of Patent Document 1, there is a need for further improvement in the shape of the surface (boiling surface) that contacts the refrigerant.

An object of the present invention is to provide an inner surface of the bottom of a container that is capable of improving the transfer efficiency of latent heat and increasing the heat transfer coefficient when the first refrigerant changes phase from the liquid phase to the gas phase. It is an object of the present invention to provide a cooling device that improves cooling efficiency by having a heat member and this heat transfer member.

In order to achieve the above object, the gist of the present invention is as follows.
(1) It is formed on the inner surface of the bottom of the container at a position corresponding to the mounting position of at least one heating element thermally connected to the outer surface of the bottom, and the heat from the heating element is transferred to the bottom of the container. In the heat transfer member, the heat transfer member heats and boils the first refrigerant by transmitting the heat to the first refrigerant in a liquid phase sealed in a lower part of the internal space, and changes the phase of the first refrigerant from the liquid phase to the gas phase. The member has a protuberance that protrudes upward from a lower surface that is fixed to the inner surface of the bottom of the container, and has a contact area on at least a portion of the upper surface of the protrusion that increases the contact area with the first refrigerant. An increased area portion is formed, and the contour shape of the raised portion is seen in at least one cross section when cut along a plane passing through the maximum thickness position of the raised portion and including the thickness direction of the raised portion. , a heat transfer member having a substantially elliptical shape.
(2) The heat transfer member according to (1), wherein the contact area increasing portion includes a porous layer made of a metal sintered body, a metal powder aggregate, or a carbon particle aggregate.
(3) The contact area increasing portion includes a plurality of periodically arranged recesses, and the recess has the narrowest width at the opening when viewed in the depth direction of the recess. 2) The heat transfer member according to item 2).
(4) The raised portion is configured by a base portion having the lower surface and a fin portion formed of a plurality of plate-shaped or columnar fins extending upward from the base portion, as described in (1) above. The heat transfer member according to any one of (3) to (3).
(5) The raised portion is constituted by a base portion raised upward from the lower surface and a fin portion formed of a plurality of plate-shaped or columnar fins extending upward from the base portion. The heat transfer member according to any one of (1) to (4) above.
(6) The raised portion has a ratio (major/minor axis ratio B/A) of the length (B) of the lower surface to the maximum thickness (A) of 1.2 or more and 3 .9 or less, the heat transfer member according to any one of (1) to (5) above.
(7) a container in which at least one heating element is thermally connected to the outer surface of the bottom and a liquid-phase first refrigerant is sealed in the lower part of the inner space; , a cooling device including a condensing pipe extending through the container and through which a second refrigerant flows, the cooling device being connected to an inner surface of the bottom of the container and an outer surface of the bottom is formed at a position corresponding to the mounting position of at least one heating element thermally connected to the heating element, and transmits heat from the heating element to a liquid phase first refrigerant sealed in a lower part of the internal space of the container. a heat transfer member that heats and boils the first refrigerant and changes the phase of the first refrigerant from a liquid phase to a gas phase; a raised part raised upward from the raised part, a contact area increasing part for increasing the contact area with the first refrigerant is formed on at least a part of the upper surface of the raised part, and a contour of the raised part. A cooling device characterized in that the shape has a substantially elliptical shape when viewed in at least one cross section when cut on a plane passing through the maximum thickness position of the raised portion and including the thickness direction of the raised portion. .

According to the present invention, there is provided a heat transfer member that improves the transfer efficiency of latent heat when the first refrigerant undergoes a phase change from a liquid phase to a gas phase, thereby increasing the heat transfer coefficient, and cooling by having this heat transfer member. It becomes possible to provide a cooling device with improved efficiency.

FIG. 1 is a perspective view showing the main parts of a cooling device having a heat transfer member according to a first embodiment of the present invention. 2 is an enlarged view of only the heat transfer member extracted from the cooling device of FIG. 1, with FIG. 2(a) being a perspective view and FIG. 2(b) being a virtual plane of FIG. 2(a). It is a sectional view when cut along M1. FIG. 3A is a diagram illustrating step 1 of steps 1 to 6 performed when determining the shape of the raised portion. FIG. 3B is a diagram illustrating procedure 2. FIG. 3C is a diagram illustrating procedure 3. FIG. 3D is a diagram illustrating step 4. FIG. 3E is a diagram illustrating procedure 5. FIG. 3F is a diagram illustrating step 6. FIG. 3G is a diagram illustrating the approximately elliptical shape of the upper surface of the protuberance determined by steps 1 to 6. FIG. 4 is a diagram showing the structure of a heat transfer member according to a second embodiment of the present invention, with FIG. 4(a) being a perspective view and FIG. 4(b) being a virtual plane M2 of FIG. 4(a). It is a sectional view when cut. FIG. 5 is a diagram showing the structure of a heat transfer member according to a third embodiment of the present invention, in which FIG. 5(a) is a perspective view and FIG. 5(b) is a virtual plane M3 of FIG. 5(a). It is a sectional view when cut. FIG. 6 is a diagram showing the structure of a heat transfer member according to a fourth embodiment of the present invention, in which FIG. 6(a) is a perspective view and FIG. 6(b) is a virtual plane M4 of FIG. 6(a). It is a sectional view when cut. FIG. 7 is a diagram showing the structure of a heat transfer member according to a fifth embodiment of the present invention, in which FIG. 7(a) is a perspective view and FIG. 7(b) is a virtual plane M5 of FIG. 7(a). It is a sectional view when cut. FIG. 8 shows the measurement and calculation of heat flux and thermal resistance using a cooling device having a heat transfer member of an example of the present invention and a heat transfer member of a comparative example, and the horizontal axis is the calculated heat flux, and the calculated thermal resistance is FIG.

Next, heat transfer members according to some embodiments of the present invention will be described below.

<Heat transfer member>
(First embodiment)
FIG. 1 is a perspective view showing the main parts of a cooling device having a heat transfer member according to a first embodiment of the present invention, and is shown in a transparent state so that the internal structure of a container constituting the cooling device can be seen. 2 is an enlarged view of only the heat transfer member extracted from the cooling device of FIG. 1, with FIG. 2(a) being a perspective view and FIG. 2(b) being a virtual plane of FIG. 2(a). It is a sectional view when cut along M1.

As shown in FIG. 1, the heat transfer member 10 according to the first embodiment includes at least one heating element that is located on the inner surface 31a of the bottom 31 of the container 30 and is thermally connected to the outer surface 31b of the bottom 31. 4, and heats the first refrigerant R1 by transmitting heat from the heating element 4 to the liquid phase first refrigerant R1 sealed in the lower part of the internal space S of the container 30. and a heat transfer member 10 that boils and changes the phase of the first refrigerant R1 from a liquid phase to a gas phase. As shown in FIGS. 2(a) and 2(b), this heat transfer member 10 has a raised portion 11 raised upward from a lower surface 11a fixed to an inner surface 31a of a bottom portion 31 of a container 30. A contact area increasing portion 12 is formed on at least a portion of the upper surface 11b of the portion 11 to increase the contact area with the first refrigerant R1. Here, the contour shape of the raised portion 11 is approximately elliptical when viewed in at least one cross section when cut in a plane passing through the maximum thickness position 11c of the raised portion 11 and including the thickness direction of the raised portion 11. has.

Thereby, by making the cross-sectional shape of the surface (boiling surface) of the heat transfer member 10 in contact with the liquid-phase first refrigerant R1, that is, the upper surface 11b of the raised portion 11, into a substantially elliptical shape, it is possible to form a straight or circular shape. The heat flux on the boiling surface can be made more uniform than in the case where the Therefore, the heat transfer coefficient on the upper surface 11b of the raised portion 11 can also be made uniform. In addition, as the heat flux at the boiling surface approaches uniformity, it becomes possible to configure the structure so that there are no parts where the heat flux exceeds the maximum heat flux and the heat transfer coefficient decreases within the rated operating range. , the heat transfer coefficient in the heat transfer member 10 can be effectively increased, thereby improving the cooling performance of the cooling device. In particular, by providing the contact area increasing portion 12 on the raised portion 11, the contact area of the boiling surface with the first refrigerant R1 is expanded, thereby reducing the heat flux at the boiling surface and increasing the heat transfer coefficient in the heat transfer member 10. It is possible to further improve the cooling performance of the cooling device.

(heat transfer member)
The heat transfer member 10 is configured to be able to contact the first refrigerant R1 sealed in the internal space S of the container 30 and transfer heat through the first refrigerant R1. It can be used in various heat transfer devices such as. Note that the heat transfer member 10 of the first embodiment shown in FIG. 1 is used by being attached to a cooling device 1.

Here, the heat transfer member 10 is an inner surface 31a of the bottom 31 of the container 30 constituting the cooling device 1, and includes at least one heating element (not shown) that is thermally connected to the outer surface 31b of the bottom 31. It is formed at a position corresponding to the mounting position P, and heats and boils the first refrigerant R1 by transmitting heat from the heating element 4 to the liquid phase first refrigerant R1 sealed in the lower part of the internal space S of the container 30. to change the phase of the first refrigerant R1 from the liquid phase to the gas phase. Note that the first refrigerant R1 exists in the internal space S of the container 30 in a phase-changed state between a liquid phase state and a gas phase state. ), the first refrigerant in the gas phase may be given a different symbol from R1(g).

The interior space S of the container 30 in which the heat transfer member 10 is provided is a space that is sealed from the outside environment, and is depressurized by degassing. This prevents leakage of the liquid-phase first refrigerant R1 (L) and gas-phase first refrigerant R1 (g) from the container 30, and adjusts the pressure of the internal space S to operate at a desired operating temperature. is configured to do so.

The heat transfer member 10 is provided so that the lower surface 11a is fixed to the inner surface 31a of the bottom 31 of the container 30. Here, as a method of providing the heat transfer member 10 in the container 30, for example, a method of integrally molding the heat transfer member 10 on the inner surface 31a of the container 30 using a mold, a method of forming the heat transfer member 10 on the inner surface 31a of the container 30 using a mold, or a method of forming the heat transfer member 10 on the inner surface 31a of the container 30 using a mold; As another member, a method of attaching it to the inner surface of the container 30 can be mentioned.

(ridge)
The heat transfer member 10 has a protrusion 11 that protrudes upward from a lower surface 11a that is fixed to the inner surface 31a of the bottom 31 of the container 30. Here, the contour shape of the raised portion 11 is approximately elliptical when viewed in at least one cross section taken along a plane passing through the maximum thickness position 11c of the raised portion 11 and including the thickness direction Y of the raised portion 11. has. As a result, the direction in which the distance from each point of the heating element 4 to the upper surface 11b of the raised portion 11 is the shortest is a different direction for each point of the heating element 4, so that the heat received from the heating element 4 is , the lower surface 11a of the raised portion 11 can be made easier to spread in the surface direction X. In addition, since heat spreads easily in the surface direction X of the lower surface 11a in the raised portion 11, the heat flux on the upper surface 11b of the raised portion 11 can be made uniform, and furthermore, the heat transfer coefficient on the upper surface 11b can be made uniform. You can get close. Further, the raised portion 11 of the heat transfer member 10 of the present invention allows heat to spread easily in the surface direction X of the lower surface 11a, so that the heat flux at the upper surface 11b exceeds the maximum heat flux within the rated operating range. Since it becomes possible to configure the structure so that no portion where the heat transfer coefficient decreases occurs, the heat transfer coefficient in the heat transfer member 10 can be increased.

Here, the approximately elliptical shape that is the contour shape of the raised portion 11 is obtained according to the following steps 1 to 5 when viewed in a cross section cut along a plane including the thickness direction Y of the raised portion 11. It is preferable to have a substantially elliptical shape based on the shape.

(Step 1)
To determine the contour shape of the raised portion 11, first, a maximum height h of a substantially ellipse serving as a reference for the shape of the raised portion 11 and a coefficient k are set. Here, when the (cross-sectional) length of the heating element 4 is L, the coefficient k is the arc length of the half circumference of a substantially ellipse, as shown in FIG. 3A.

(Step 2)
After performing step 1, in this cross section, a point in contact with the heating element 4 and located at the center of the lower surface 11a of the raised portion 11 in the plane direction X is set as point _G0 , and one or the other end point of the heating element 4 is The point of contact is defined as a point _Gn , and the area between the point _G0 and the point _Gn , which are in contact with these heating elements 4, is divided into n sections at equal intervals (n is an arbitrary number, but a larger one is preferable). Further, the maximum thickness position 11c located above the point _G0 by the maximum height h along the thickness direction Y of the raised portion 11 is defined as a point _P0 on the substantially ellipse. Here, the positional relationship between the points G ₀ and G _n in contact with the heating element 4 and the point P ₀ on the substantially ellipse is as shown in FIG. 3B.

(Step 3)
After performing step 2, centering on the point _P0 on the approximate ellipse, set the radius to be the length d', which is k times the distance d between the point _G0 that touches the heating element 4 and the point _G1 next to it. Draw an arc C1. In addition, an arc C2 is drawn with the point _G0 as the center and the maximum height h as the radius. Here, the positional relationship between the point P ₀ on the substantially ellipse, the points G ₀ and G ₁ in contact with the heating element 4, and the arcs C1 and C2 is as shown in FIG. 3C.

(Step 4)
After performing step 3, a circular arc C3 is drawn centered on the point _G1 in contact with the heating element 4 and having a radius equal to the length h' of _the line segment _G1P0 . Here, the positional relationship between the point G1 in contact with the heating element ₄ and the circular arc C3 is as shown in FIG. 3D.

(Step 5)
After performing step 4, if the point where the arc C1 and the arc C2 intersect is set as the intersection q1, and the point where the arc C1 and the arc C3 intersect is set as the intersection q2, then the midpoint between the intersection q1 and the intersection q2 on the arc C1 Let be a point _P1 on a substantially ellipse. Here, the positional relationship among the arcs C1, C2, C3, the intersections q1, q2, and the point _P1 on the approximate ellipse is as shown in FIG. 3E.

(Step 6)
After performing step 5, the above steps 3 to 5 are performed centering on point P ₁ on the approximately ellipse to obtain an adjacent point P ₂ on the approximately ellipse. Thereafter, points on adjacent approximate ellipses are determined in the same manner until the approximate ellipse intersects with the heating element 4. At this time, the maximum height h of the approximate ellipse and the coefficient k in step 1 are adjusted so that the n-th point P _n on the approximate ellipse is found at the position where the approximate ellipse intersects with the heating element 4 . Here, the positional relationship between the points G ₀ to G _n in contact with the heating element 4 and the points P ₀ to P _n on the substantially ellipse is as shown in FIG. 3F.

As shown in FIG. 3G, the approximately elliptical shape of the upper surface 11b of the raised portion 11 determined by performing steps 1 to 6 is such that the shortest distance from each point of the heating element 4 to the upper surface 11b of the raised portion 11 is the maximum. The direction that is the same as the height h and has the shortest distance is a different direction for each point on the heating element 4, and the destination of that direction spreads over the entire upper surface 11b. Therefore, the heat received from the heating element 4 can be spread almost evenly over the entire upper surface 11b of the raised portion 11. Furthermore, since the heat flux on the upper surface 11b of the raised portion 11 can be made more uniform, the heat transfer coefficient on the upper surface 11b can also be made more uniform.

The raised portion 11 in the present invention is a plane including the thickness direction Y, and when viewed in at least one cross section when cut, the raised portion 11 is defined in the thickness direction Y based on the approximately elliptical shape obtained by steps 1 to 6. It is preferable that one or both of the surface direction X of the lower surface has a contour shape that falls within the range of ±10%, and more preferably that it has a contour shape that falls within the range of ±5%.

Further, the raised portion 11 in the present invention is a lower surface of the raised portion 11 with respect to the maximum thickness (A) of the raised portion 11 when viewed in at least one cross section when cut in a plane including the thickness direction Y. It is preferable that the ratio of the length (B) of 11a (major axis ratio B/A) is in the range of 1.2 or more and 3.9 or less. As a result, the shape of the raised portion 11 approaches the substantially elliptical shape obtained by steps 1 to 6 described above, so that the heat received from the heating element 4 is easily spread in the surface direction X of the lower surface 11a of the raised portion 11. be able to.

(Increased contact area)
A contact area increasing part 12 that increases the contact area with the first refrigerant R1 is formed on the raised part 11 of the heat transfer member 10 so as to constitute at least a part of the upper surface 11b. Thereby, the heat of the heating element 4 is transmitted from the inner surface 31a of the bottom 31 of the container 30 to the lower surface 11a of the raised portion 11, and is directed upward from the lower surface 11a of the raised portion 11 to the raised portion where the increased contact area 12 is formed. The refrigerant is transmitted from the upper surface 11b of the portion 11 to the first refrigerant R1. At this time, since the contact area increasing portion 12 is formed on the upper surface 11b of the raised portion 11, which is the boiling surface, the contact area between the heat transfer member 10 and the first refrigerant R1 is expanded, so that the heat flux at the boiling surface is reduced. The heat transfer coefficient in the heat transfer member 10 can be further increased.

Here, it is preferable that the contact area increasing portion 12 is provided so as to constitute the entire upper surface 11b of the raised portion 11. As a result, the contact area between the heat transfer member 10 and the first refrigerant R1 increases over the entire upper surface 11b of the raised portion 11, which becomes the boiling surface, so that variation in heat flux in the heat transfer member 10 is suppressed, and the heat transfer coefficient can be further enhanced.

In particular, in the heat transfer member 10 of this embodiment, the contact area increasing portion 12 is formed on the surface of the base material 13 by a fine structure. In particular, the contact area increasing portion 12 of this embodiment includes a porous layer made of a metal sintered body, a metal powder aggregate, or a carbon particle aggregate. Thereby, the contact area of the raised portion 11 with the first refrigerant R1 is increased by the porous layer, so that the heat transfer coefficient of the heat transfer member 10 can be increased. Further, a fine structure can be formed by a simple method such as applying metal powder to the upper surface of a member that is the base of the raised portion 11 and firing it.

Here, among the materials of the porous layer constituting the contact area increasing portion 12, the metal species constituting the metal sintered body or the metal powder may be a metal species that does not cause an electrochemical reaction with the first refrigerant R1. Examples include one or more of copper and copper alloys. Further, the form of the metal material before sintering the metal sintered body includes, for example, one or more of metal powder, metal fiber, metal mesh, metal braid, and metal foil. A metal sintered body can be formed by firing a metal material with a heating means such as a furnace. Further, the carbon particles constituting the carbon particle aggregate are not particularly limited, and examples thereof include carbon nanoparticles and carbon black.

On the other hand, a material that does not react with the first refrigerant R1 can be used as a material constituting the base material 13 on which the contact area increasing portion 12 is formed, such as a thermally conductive material. Specific examples of the material constituting the base material 13 include metal materials such as copper, copper alloy, aluminum, aluminum alloy, iron alloy (for example, stainless steel), and carbon materials such as graphite.

In the heat transfer member 10 of the present invention, when the heat generating element 4 generates heat and the temperature rises, the heat of the heat generating element 4 is transmitted to the raised portion 11 of the heat transfer member 10 via the bottom portion 31 of the container 30, and the raised portion Since the first refrigerant R1 (L) located around the outside of the raised portion 11 is also transmitted from the raised portion 11 of the heat transfer member 10 to the increased contact area portion 12, the first refrigerant R1(L) is heated by the raised portion 11 of the heat transfer member 10 and the increased contact area portion 12. The temperature increases and reaches boiling temperature, and the first refrigerant R1(g) in the gas phase is generated. In particular, in this embodiment in which the contact area increasing portion 12 is constituted by a porous layer, the liquid phase first refrigerant R1 (L) is caused to flow into the porous layer and is held for a period of time until bubbles grow. Therefore, the heat transfer characteristics can be further improved, and it can also contribute to suppressing the occurrence of dryout.

(Second embodiment)
FIG. 4 is a diagram showing the structure of a heat transfer member according to a second embodiment of the present invention, with FIG. 4(a) being a perspective view and FIG. 4(b) being a virtual plane M2 of FIG. 4(a). It is a sectional view when cut. In the heat transfer member 10A of the second embodiment, the contact area increasing portion 12A includes a plurality of periodically arranged recesses 14, and the recesses 14 are arranged at the openings 14a when viewed in the depth direction of the recesses 14. Constructed to have the narrowest width. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals to omit or simplify the description, and mainly differences will be described.

Here, the heat transfer member 10A includes a plurality of recesses 14 arranged periodically on the upper surface 11b of the raised portion 11A as a contact area increasing portion 12A. Thereby, the contact area between the heat transfer member 10 and the first refrigerant R1 is expanded, so that the heat flux at the boiling surface can be reduced. Further, since the recessed portion 14 formed in the upper surface 11b of the raised portion 11A functions as a boiling point for the first refrigerant R1(L) in the liquid phase, it is possible to further increase the heat transfer coefficient in the heat transfer member 10A. can.

Further, as shown in FIG. 4(b), the recess 14 on the upper surface 11b of the raised portion 11A becomes wider as it goes from the opening 14a toward the lower surface 11a when viewed in the depth direction of the recess 14. is preferred. This promotes the growth of bubbles of the gas phase first refrigerant R1(g) inside the recess 14, so that the heat transfer coefficient to the upper surface 11b of the raised portion 11A can be further increased.

The shape of the opening 14a of the recess 14 provided on the upper surface 11b of the raised portion 11A in plan view (viewed from the direction facing the upper surface 11b) is not particularly limited, and for example, as shown in FIG. 4(a). It can be made into a circular shape. Further, the opening width of the opening 14a of the recess 14 is not particularly limited, and may be in the range of 0.03 mm or more and 0.70 mm or less, for example.

(Third embodiment)
FIG. 5 is a diagram showing the structure of a heat transfer member according to a third embodiment of the present invention, in which FIG. 5(a) is a perspective view and FIG. 5(b) is a virtual plane M3 of FIG. 5(a). It is a sectional view when cut. In the following description, the same components as those in the first embodiment or the second embodiment are given the same reference numerals to omit or simplify the explanation, and mainly differences will be explained.

In the heat transfer member 10B of the third embodiment, the raised portion 11B is a fin portion consisting of a base portion 15B having a lower surface 11a and a plurality of plate-shaped or columnar fins 16 extending upward from the base portion 15B. 17. In this embodiment, the upper end surface 17a of the fin portion 17 forms the contour shape of the upper surface 11b of the raised portion 11B, which is similar to the upper surface of the raised portion in the first embodiment. In this way, the raised portion 11B in the present invention only needs to be provided on at least a portion of the heat transfer member 10, and does not necessarily need to be provided on the entire surface of the heat transfer member 10.

In this embodiment, the fins 16 expand the contact area between the heat transfer member 10B and the first refrigerant R1, and the first refrigerant R1 flows upward along the fins 16 due to convection, so that the first refrigerant R1 increases. Heating is accelerated, and furthermore, the tips of the fins 16 become foaming nuclei, making it easier for the first refrigerant R1 to undergo nucleate boiling. Therefore, heat transfer from the heating element 4 to the liquid phase first refrigerant R1 (L) can be facilitated.

Among these, the base portion 15B constitutes the lower surface 11a of the raised portion 11B. It is preferable that the planar shape of the base portion 15B (the shape of the lower surface 11a) corresponds to the shape of the contact surface of the heating element 4 attached to the mounting position P of the heating element 4. For example, when the contact surface of the heating element 4 attached at the attachment position P is rectangular, it is preferable that the planar shape of the base portion 15B is rectangular as shown in FIG. Note that the planar shape of the base portion 15B includes various shapes such as a rectangular shape, a circle, a triangle, and a polygon.

Moreover, it is preferable that the three-dimensional shape of the base portion 15B is a shape that bulges upward from the lower surface 11a. Among them, the contour shape of the raised portion of the base portion 15B may have a substantially elliptical shape when viewed in at least one cross section when cut along a plane passing through the maximum thickness position and including the thickness direction Y. More preferred. More preferably, it has a substantially elliptical shape based on the shape determined according to steps 1 to 5 above.

On the other hand, the fin portion 17 includes a plurality of plate-shaped or column-shaped fins 16 provided so as to extend upward from the base portion 15B. In the heat transfer member 10B according to the present embodiment, since the upper end surface of the fin portion 17 forms the contour shape of the raised portion 11B, the upper end surface of the fin portion 17 forms the contour shape of the raised portion 11B, so that , a contact area increasing portion 12B is configured.

Here, the plurality of fins 16 constituting the fin portion 17 are preferably aligned at intervals along the surface direction of the lower surface 11a of the raised portion 11B. The number of fins 16 provided is not limited to the number shown in FIGS. 5(a) and 5(b), and can be increased or decreased as necessary.

The fins 16 can be formed by, for example, attaching (fixing) plate-shaped fins made separately from the base portion 15B to the inner surface 31a of the container 30 by soldering, brazing, welding, sintering, etc.; Examples include a method of cutting the inner surface of 30, an extrusion method, an etching method, etc.

(Fourth embodiment)
FIG. 6 is a diagram showing the structure of a heat transfer member according to a fourth embodiment of the present invention, in which FIG. 6(a) is a perspective view and FIG. 6(b) is a virtual plane M4 of FIG. 6(a). It is a sectional view when cut. Note that the same components as those in the first embodiment, second embodiment, or third embodiment are given the same reference numerals, and the explanation thereof will be omitted or simplified, and differences will be mainly explained.

The heat transfer member 10C of the fourth embodiment has a raised portion 11C that includes a base portion 15C that is raised upward from the lower surface 11a, and a plurality of plate-shaped or columnar fins that extend upward from the base portion 15C. 16. The heat transfer member 10C of the fourth embodiment has the same basic structure as the heat transfer member 10B of the third embodiment, but the upper surface 15a of the base portion 15C forms the contour shape of the raised portion 11C. It is a feature.

In this embodiment, in addition to the effect of the fins 16 described above, the upper surface 15a of the base portion 15C has a substantially elliptical contour shape, so that the heat received from the heating element 4 is transferred to the surface of the lower surface 11a of the raised portion 11. Since it can be made easier to spread in the direction X, the heat transfer coefficient in the heat transfer member 10 can be further increased.

The heat transfer member 10C according to the present embodiment includes a plurality of plate-shaped or columnar fins 16 extending upward from a base portion 15C forming the outline shape of the raised portion 11C. . In the heat transfer member 10C according to the present embodiment, since the upper end surface of the base portion 15C forms the contour shape of the raised portion 11C, there are A contact area increasing portion 12C is configured.

(Fifth embodiment)
FIG. 7 is a diagram showing the structure of a heat transfer member according to a fifth embodiment of the present invention, with FIG. 7(a) being a perspective view and FIG. 7(b) being a virtual plane M5 of FIG. 7(a). It is a sectional view when cut. Note that the same components as in any of the first to fourth embodiments are given the same reference numerals, and the explanation thereof will be omitted or simplified, and the differences will be mainly explained.

In the first to fourth embodiments described above, the contour shape of the raised portion 11 has a substantially elliptical shape when viewed in cross section taken along a plurality of planes including the thickness direction Y of the raised portion 11. Although the configuration is shown, the present invention is not limited to this configuration. For example, as shown in FIG. 7B, the protrusion 11 may have a substantially elliptical shape when viewed in cross section along at least one plane including the thickness direction Y. At this time, the shape when cut along another plane including the thickness direction Y may be a different shape such as a rectangle.

<Cooling device>
Next, a cooling device according to an embodiment of the present invention will be described below.
The cooling device 1 of this embodiment includes a container 30 and a condensing pipe 50.

In the container 30, at least one heating element is thermally connected to the outer surface 31b of the bottom portion 31, and a liquid phase first refrigerant R1 (L) is sealed in the lower part of the internal space S.

The condensing pipe 50 is disposed at an upper position of the internal space S of the container 30 so as to penetrate the container 30 and extend both inside and outside the container 30, and the second refrigerant R2 flows through the inside of the condensing pipe 50. . The inside of the condensing pipe 50 and the internal space S of the container 30 are not communicated with each other. That is, the second refrigerant R2 passing through the condensing pipe 50 includes the first liquid refrigerant R1 (L) sealed in the lower part of the internal space S of the container 30 and the first refrigerant R1 (L) in the liquid phase. does not come into contact with any of the first refrigerant (g) that has boiled into a gas phase. The condensing pipe 50 flows through the second refrigerant R2 that absorbs heat from the first refrigerant (g) in the gas phase, condenses the first refrigerant R1 (g) in the gas phase, and converts the first refrigerant R1 in the liquid phase to the first refrigerant R1 in the liquid phase. This is a member provided to change the phase to (L). In order to improve the cooling efficiency, the condensing tube 50 may have a portion increasing the surface area, such as unevenness, on the outer surface of the condensing tube 50, but it may also have a smooth surface. Further, the inner surface of the condensing tube 50 may also have a portion that increases the surface area, such as an uneven surface, but may also be a smooth surface.

The cooling device 1 is provided with a plurality of condensing pipes, and in FIG. 1, two condensing pipes 50, 50 are provided. The condensing pipes 50 are arranged in parallel in two stages, upper and lower, in the interior space S of the container 30 so as to be substantially coplanar with each other. The cross-sectional shape of the condensing tube 50 is not particularly limited, and includes various shapes such as a circular shape as shown in FIG. 1, an elliptical shape, a flattened shape, a square shape, and a rounded rectangular shape.

The method for attaching the condensing pipes 50 to the container 30 is to provide two through holes 51, 51 for each condensing pipe 50 in the container 30, and to fit the condensing pipes 50 tightly into these through holes 51, 51. The condensing pipe 50 can be attached to the container 30 while keeping the internal space S in a sealed state.

A liquid-phase secondary refrigerant R2 flows through the condensing tube 50 in one direction (from right to left in FIG. 1) along the extending direction of the condensing tube 50. Therefore, the secondary refrigerant R2 flows through the wall surface of the condensing pipe 50 and through the upper part of the internal space S of the container 30. The secondary refrigerant R2 is cooled, for example, to a liquid temperature lower than the maximum allowable temperature of the heating element.

The material of the container 30 is not particularly limited, and a wide variety of materials can be used, such as copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, stainless steel, titanium, titanium alloy, etc. .

The material of the condensing tube 50 is not particularly limited, and examples thereof include copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, iron alloy (for example, stainless steel), titanium, titanium alloy, and the like.

The primary refrigerant R1 (L) is not particularly limited, and a wide variety of materials can be used, such as electrically insulating refrigerants. Specific examples include water, fluorocarbons, cyclopentane, ethylene glycol, and mixtures thereof. Among these primary refrigerants R1 (L), fluorocarbons, cyclopentane, and ethylene glycol are preferred from the viewpoint of electrical insulation, and fluorocarbons are particularly preferred.

The secondary refrigerant R2 is not particularly limited, and examples thereof include water, antifreeze (containing ethylene glycol as a main component, for example), and the like.

The cooling device 1 includes the heat transfer member 10 as described above.

<Cooling mechanism of cooling device>
Next, the cooling mechanism of the cooling device 1 of the present invention will be explained below.
First, when the heating element generates heat, the heat is transferred to the heat transfer member 10 through the bottom of the container 30 constituting the cooling device 1, the temperature of the heat transfer member 10 rises, and the heat transfer member 10 is sealed in the lower part of the internal space S of the container 30. The liquid-phase primary refrigerant R1 (L) is heated, and the liquid-phase primary refrigerant R1 (L) undergoes a phase change to the gas-phase primary refrigerant R1 (g), which releases heat from the heating element. is absorbed as latent heat. Next, the primary refrigerant R1 (g) that has changed to the gas phase moves upward through the internal space S of the container 30 and comes into contact with the condensing pipe 50. A low-temperature secondary refrigerant R2 flows inside the condensing pipe 50. Therefore, when the primary refrigerant R1 (g) that has changed to the gas phase comes into contact with or approaches the outer surface of the condensing tube 50, it releases latent heat due to the heat exchange action of the condensing tube 50, and changes from the gas phase to the liquid phase. The phase changes to During the phase change from the gas phase to the liquid phase, the latent heat released from the gas phase primary refrigerant R1 (g) is transferred to the secondary refrigerant R2 flowing through the condensing pipe 50. Further, the primary refrigerant R1 (L) that has undergone a phase change to the liquid phase flows back through the internal space S of the container 30 from the upper part to the lower part under the action of gravity. The primary refrigerant R1 (L) repeats a phase change from a liquid phase to a gas phase and from a gas phase to a liquid phase in the sealed internal space S of the container 30. In addition, in the cooling device 1, when the primary refrigerant R1 repeats a phase change from a liquid phase to a gas phase and a phase change from a gas phase to a liquid phase in the internal space of the container 30, a There is no need to form a circulation path for the next refrigerant R1. Therefore, the container 30 can be formed with a simple structure. The secondary refrigerant R2, which has received heat from the gas phase primary refrigerant R1 (g), flows from the inside of the cooling device 1 to the outside along the extending direction of the condensing pipe 50, thereby generating heat from the heating element. is transported to the outside of the cooling device 1.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and includes all aspects included in the concept of the present invention and the scope of the claims. It can be modified to .

The present invention will be explained in more detail below based on Examples, but the present invention is not limited thereto.

(Example of the present invention)
A cooling device 1 according to an example of the present invention has an internal structure shown in FIG. Among these, as the container 30, a rectangular parallelepiped copper container was used. Furthermore, the heat transfer member 10 used was one made of a copper material and having a raised portion 11 raised from a square lower surface 11a. Here, the contour shape of the raised portion 11 is approximately an ellipse with a maximum height h when viewed in two cross sections including the thickness direction Y and cut along a diagonal line of the square that constitutes the lower surface 11a. is 6 mm and the coefficient k is 2.27, it falls within a range of ±5% in both the thickness direction Y and the lower surface direction It is configured to have a contoured shape. Further, a copper powder sintered body was provided as a contact area increasing portion 12 on the entire upper surface 11b of the raised portion 11. Water was used as the first refrigerant R1 (L), and the interior space S of the container 30 was filled with the first refrigerant R1 (L), and the pressure was reduced and the water was sealed.

(Comparative example)
The cooling device 1 of the comparative example was configured in the same manner as the example of the present invention except that the contact area increasing portion 12 was not provided on the upper surface 11b of the raised portion 11.

(Performance evaluation)
Performance evaluation of the cooling device was performed under the following conditions.
For each of the cooling devices of the example and comparative example, a 50 to 400 W heater (heating element) is connected to the outer surface of the bottom of the container via thermal conductive grease to input heat, and a second The temperature difference between the refrigerant temperature and the heater temperature was measured. Then, the measured temperature difference was divided by the amount of heat input to calculate the thermal resistance (K/W), and the performance of the cooling device was evaluated. Note that water was used as both the first refrigerant and the second refrigerant sealed in the internal space of the container.

FIG. 8 is a diagram plotting the heat fluxes measured and calculated using the cooling devices of the inventive example and the comparative example on the horizontal axis and the calculated heat transfer coefficient on the vertical axis. From the results in FIG. 8, it can be seen that the cooling device according to the present invention has a lower thermal resistance at all heat fluxes than the cooling device according to the comparative example, so that the heat transfer coefficient is improved.

1 Cooling device 10, 10A to 10D Heat transfer member 30 Container 31 Bottom of the container 31a Inner surface of the bottom of the container 31b Outer surface of the bottom of the container 11 Raised portion 11a Lower surface of the raised portion 11b Upper surface of the raised portion 11c Maximum thickness position of the raised portion 12, 12A to 12D contact area increasing portion 13 base material 14 recess 14a opening of recess 15B, 15C base portion 15a upper surface of base portion 16 fin 17 fin portion 17a upper end surface of fin portion 4 heating element h reference for shape of raised portion Maximum height of the approximately ellipse P Mounting position of the heating element R1 First refrigerant R1 (L) First refrigerant in liquid phase R1 (g) First refrigerant in gas phase R2 Second refrigerant S Internal space X Lower surface of the raised part Planar direction Y Thickness direction of the raised part

Claims (6)

It is formed on the inner surface of the bottom of the container at a position corresponding to the mounting position of at least one heating element thermally connected to the outer surface of the bottom, and is configured to transfer heat from the heating element to the inner space of the container. A heat transfer member that heats and boils the first refrigerant by transmitting it to a liquid-phase first refrigerant sealed in a lower part, and changes the phase of the first refrigerant from a liquid phase to a gas phase,
The heat transfer member has a protuberance that protrudes upward from a lower surface that is fixed to the inner surface of the bottom of the container ,
The contour shape of the raised part has a substantially elliptical shape when viewed in at least one cross section when cut along a plane that passes through the maximum thickness position of the raised part and includes the thickness direction of the raised part ,
A contact area increasing portion that increases a contact area with the first refrigerant is formed on at least a portion of the upper surface of the raised portion;
The contact area increasing portion includes a plurality of periodically arranged recesses, and
The heat transfer member is characterized in that the recess has the narrowest width at the opening when viewed in the depth direction of the recess . The heat transfer member according to claim 1, wherein the contact area increasing portion includes a porous layer made of a metal sintered body, a metal powder aggregate, or a carbon particle aggregate. 3. The protruding portion is configured by a base portion having the lower surface and a fin portion including a plurality of plate-shaped or columnar fins extending upward from the base portion. heat transfer member. 1 . The raised portion is configured by a base portion raised upward from the lower surface and a fin portion formed of a plurality of plate-shaped or columnar fins extending upward from the base portion. 3. The heat transfer member according to any one of 3 to 3. The raised portion has a ratio of the length (B) of the lower surface to the maximum thickness (A) (major axis ratio B/A) of 1.2 or more and 3.9 or less, when viewed in the at least one cross section. The heat transfer member according to any one of claims 1 to 4 , which is in the range of. At least one heating element is thermally connected to the outer surface of the bottom, and a liquid-phase first refrigerant is sealed in the lower part of the inner space;
A cooling device comprising: a condensing pipe extending through the container at an upper position of the internal space of the container, and through which a second refrigerant flows;
The cooling device is formed on the inner surface of the bottom of the container at a position corresponding to the mounting position of at least one heating element thermally connected to the outer surface of the bottom, and the cooling device is configured to absorb heat from the heating element. The heat transfer member includes a heat transfer member that heats and boils the first refrigerant by transmitting the heat to the liquid phase first refrigerant sealed in the lower part of the internal space of the container, and changes the phase of the first refrigerant from the liquid phase to the gas phase. death,
The heat transfer member has a protuberance that protrudes upward from a lower surface that is fixed to the inner surface of the bottom of the container ,
The contour shape of the raised part has a substantially elliptical shape when viewed in at least one cross section when cut along a plane that passes through the maximum thickness position of the raised part and includes the thickness direction of the raised part ,
A contact area increasing portion that increases a contact area with the first refrigerant is formed on at least a portion of the upper surface of the raised portion;
The contact area increasing portion includes a plurality of periodically arranged recesses, and
The cooling device is characterized in that the recess has the narrowest width at the opening when viewed in the depth direction of the recess .

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