JP2008281253A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve cooling performance of a cooling device by improving discharging efficiency of a vapor-phase refrigerant by increasing the supply of liquid-phase refrigerant, promoting heat diffusion to the inside of a porous member, and encouraging boiling. <P>SOLUTION: A projecting portion 115 is disposed in a region corresponding to a heating element 10, of an inner face 114 of a wall portion 111 constituting a refrigerant tank 110. In fixing the porous member to the refrigerant tank, a part 131 opposed to the projecting portion 115, of the porous member 130 is compressed by the projecting portion 115 to reduce its porosity in comparison with that of the other region. Thus effective heat conductivity of the region 131 opposed to the projecting portion 115 can be increased in comparison with that of the other region, and the heat diffusion to the inside of the porous member 130 from the heating element 10 can be promoted. As the region having the relatively low porosity and the region having relatively high porosity can be formed, the boiling of the liquid-phase refrigerant can be encouraged, the discharging efficiency of the gas-phase refrigerant can be improved, and the supply of liquid-phase refrigerant can be increased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cooling device that cools a heating element such as a semiconductor element by latent heat transfer caused by vaporization and liquefaction of a refrigerant.

  As a cooling device that cools a heating element by latent heat transfer due to vaporization and liquefaction of refrigerant, for example, Patent Document 1 stores a liquid-phase refrigerant inside, and a heating element is installed on the outer surface of a wall portion. A porous member having a mesh structure having a large number of pores on the inner surface of the part is installed, and by a capillary force of the porous member, a refrigerant tank that transports a liquid-phase refrigerant to a region corresponding to the heating element, and a heat of the heating element The thing of the structure provided with the thermal radiation part which returns the vaporized refrigerant to a refrigerant tank after liquefying is shown.

Moreover, in patent document 2, in order to accelerate | stimulate the boiling of a refrigerant | coolant by improving the capillary force of a porous member in such a structure, as a porous member, a pore diameter is 100 micrometers or less, and the porosity is 80. A structure using a porous metal that is at least% is proposed.
JP 2005-268658 A JP 2006-177582 A

  The cooling device having the configuration shown in Patent Document 1 is a cooling system that removes heat from a heating element by the latent heat generated when a liquid-phase refrigerant is vaporized, particularly boiled, inside a porous member. Then, the boiling of the liquid refrigerant greatly affects the cooling performance. Here, in the boiling of the liquid phase refrigerant inside the porous member, the amount of liquid phase refrigerant supplied to the region corresponding to the heating element in the porous member, the transfer of heat from the heating element to the inside of the porous member In order to improve the cooling capacity of the cooling device, the supply amount of the liquid phase refrigerant is affected by the ease, the ease of boiling, and the amount of refrigerant vaporized by the heat of the heating element from the inside of the porous member. It is only necessary to satisfy one of the following: increasing the thermal conductivity, promoting thermal diffusion into the porous member, facilitating boiling, and improving the discharge performance of the gas-phase refrigerant.

  Moreover, when satisfying these simultaneously, the cooling performance of the cooling device can be most improved, but characteristics such as the thickness, pore diameter, porosity, etc. of the porous member required to satisfy each of them can be obtained. Since they are different, it is difficult to satisfy them simultaneously only by uniformly defining the characteristics of the entire porous member.

  That is, regarding the thickness and pore diameter of the porous member, in order to increase the supply amount of the liquid refrigerant of the porous member, as in Patent Document 2, the pore diameter is reduced to increase the capillary force, In order to increase the absolute amount of the liquid-phase refrigerant that moves through the porous member by increasing the thickness of the porous member, it is necessary to improve the discharge performance of the gas-phase refrigerant from the porous member. Needs to increase the pore diameter or make the porous member thin so that the gas-phase refrigerant is easily discharged. Moreover, in order to make boiling easy to occur, it is necessary to increase the surface area of the porous member by increasing the thickness so that the amount of foaming nuclei that become buds for starting boiling increases.

  Regarding the porosity of the porous member, in order to promote thermal diffusion into the porous member, it is necessary to increase the proportion of the metal in the porous member, that is, to decrease the porosity. In order to increase the supply amount of the liquid-phase refrigerant and improve the discharge performance of the gas-phase refrigerant, in order to increase the amount of movement of the refrigerant, the ratio of pores inside the porous member is increased, that is, the porosity is increased. There is a need to. Moreover, in order to make boiling easy to occur, it is necessary to increase the porosity and increase the surface area of the porous member so that the amount of foam nuclei that become buds at the start of boiling increases.

  In view of the above points, the present invention provides cooling of the cooling device by increasing the supply amount of the liquid-phase refrigerant, promoting thermal diffusion into the porous member, facilitating boiling, and improving the discharge performance of the gas-phase refrigerant. It is an object of the present invention to provide a cooling device having a configuration capable of improving performance.

  In order to achieve the above object, the present invention is directed to the porous member (130) in a region where the refrigerant tank (110) corresponds to the heating element (10) in the inner surface (114) of the wall (111). It has the 1st characteristic that it has the protrusion part (115) which protrudes.

  According to this, since the heat of the heating element is transmitted to the porous member via the protrusion provided on the inner surface of the refrigerant tank, the heating element is more porous than the case without the protrusion. It is possible to promote thermal diffusion into the material member. As a result, since heat diffuses inside the porous member, a region where boiling occurs in the porous member is expanded, so that the cooling performance of the cooling device is improved.

  Regarding the first feature, the protrusion (115) further has a height (t1) from the inner surface (114) of the wall portion smaller than the thickness (t2) of the porous member (130). The material member (130) has a void ratio higher than that of the portion not facing the protrusion (115) because the portion facing the protrusion (115) in the protruding direction of the protrusion (115) is compressed by the protrusion. It can be set as the structure which has the area | region (131) where is small.

  According to this, since the porous member is provided with a region having a small porosity formed by compression by the protrusion, the effective thermal conductivity of the porous material can be made larger in the region than other regions. . For this reason, in the porous member, heat diffusion from a region having a small porosity to a surrounding region can be promoted, and as a result, heat diffusion from the heating element to the inside of the porous material member can be promoted. Therefore, the region where boiling occurs can be expanded by promoting the thermal diffusion into the porous member, so that the cooling performance of the cooling device can be improved.

  Further, by adopting such a configuration, it is possible to provide a region having a relatively low porosity and a region having a large porosity in the region corresponding to the heating element in the porous member. Thus, it is possible to simultaneously satisfy the promotion of thermal diffusion into the porous member, the promotion of boiling of the liquid-phase refrigerant, and the improvement of the discharge performance of the gas-phase refrigerant. Further, in this configuration, since the projection and the region having a small porosity are not provided in the region of the porous member that transports the liquid phase coolant to the region corresponding to the heating element, the supply amount of the liquid phase coolant is reduced. Rather, it is possible to increase the supply amount of the liquid-phase refrigerant by increasing the porosity in this region.

  In the present invention, the porous member (130) is a region corresponding to the heating element in the porous member, and the porosity on the wall side surface (132) is porous except for the surface (132). The second feature is that the void ratio is smaller than that in the member (130).

  According to this, the porosity on the wall-side surface (132) of the porous member is smaller than the porosity in the porous member (130) excluding the surface (132). Contrary to the case where the porosity is uniform throughout the porous member without providing a small portion, the proportion of the porous member base material on the surface can be increased, and the wall of the refrigerant tank The joining area of the porous member which contacts can be increased. As a result, the bonding property between the porous member and the refrigerant tank can be improved, and the diffusion of heat from the heating element into the porous member can be promoted, so that the cooling performance of the cooling device can be improved.

  Also, by adopting this configuration, the porosity can be relatively increased inside the porous member, and the porosity on the wall side surface of the porous member can be relatively reduced, so that the interior of the porous member can be reduced. It is possible to simultaneously satisfy the promotion of thermal diffusion, the promotion of boiling of the liquid-phase refrigerant, and the improvement of the discharge performance of the gas-phase refrigerant. Further, the porosity on the wall side surface (132) is reduced in the region corresponding to the heating element in the porous member, and the porosity is relatively set in the region other than the region corresponding to the heating element in the porous member. Therefore, it is possible to increase the supply amount of the liquid phase refrigerant.

  Further, according to the present invention, the porous member (130) is a space formed by being partially removed within the range corresponding to the heating element (10) and the region above it. Thus, the third feature is that it has space portions (134, 135) constituting a space larger than pores existing in other regions.

  In this case, for example, the depth (t5) of the region where the porous member (130) is partially removed can be configured by the same notch (134) as the thickness (t4) of the porous member (130), The porous member (130) is a portion where the porous member is partially removed from the surface (137) opposite to the surface in contact with the wall portion (111), and the depth (t6) of the removed portion. ) Can be constituted by a groove (135) smaller than the thickness (t4) of the porous member (130).

  According to these, in the porous member (130), a space larger than the pores existing in other regions is provided in the region corresponding to the heating element (10) and the region reaching the upper region. Therefore, it is possible to promote the discharge of the gas-phase refrigerant vaporized inside the porous member by the heat of the heating element. As a result, since the frequency of occurrence of boiling increases, the cooling performance of the cooling device is improved.

  In addition, by adopting such a configuration, it is possible to increase the thickness of the porous member without deteriorating the discharge property of the gas-phase refrigerant from the porous member. And, by increasing the thickness of the porous member, it is possible to increase the surface area inside the porous member, so it is possible to generate boiling even when the heat generation amount of the heating element is small, In this case, the cooling performance of the cooling device can be improved.

  In addition, by adopting such a configuration, the thickness of the porous member can be increased, or the pore diameter of the porous member can be reduced without deteriorating the discharge property of the gas phase refrigerant from the porous member. It is possible to increase the amount of refrigerant sucked into the porous material. Therefore, even when the heat generation amount of the heat generating element is large, a sufficient amount of liquid phase refrigerant can be supplied to the vicinity of the heat generating element, so that the cooling performance of the cooling device in this case can be improved.

  In the present invention, the heat dissipating part (220) and the refrigerant passage (223) communicating with the region corresponding to the heating element (10) in the porous member (130) in the refrigerant tank (110) are provided. One end (223b) of the passage (223) is in contact with the region corresponding to the heating element (10) in the porous member (130), and the other end (223a) of the refrigerant passage (223) is the heat radiating portion (220). And a part of the refrigerant condensed in the heat radiating section (220) is supplied to the region corresponding to the heating element (10) in the porous member (130) through the refrigerant passage (223). The fourth feature is that it is designed to be performed.

  According to this, a part of the refrigerant condensed in the heat radiating portion can be directly supplied to the region corresponding to the heating element in the porous member, so that the capillary force of the porous member causes the region corresponding to the heating element. Compared with the case of transporting the liquid-phase refrigerant, the moving distance of the liquid-phase refrigerant can be shortened, and the supply speed of the liquid-phase refrigerant to the porous member can be increased. As a result, even when the heat generation amount of the heating element increases rapidly, a sufficient amount of liquid-phase refrigerant can be supplied to the region corresponding to the heating element in the porous member, and the heating element can be sufficiently cooled. . That is, the responsiveness of the cooling device can be improved.

  Further, according to this, the supply amount of the liquid phase refrigerant to the region corresponding to the heating element in the porous member can be increased without increasing the thickness of the porous member or reducing the pore diameter. Therefore, it is possible to achieve both an increase in the supply amount of the liquid-phase refrigerant and an improvement in the discharge performance of the gas-phase refrigerant.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
First, an overall configuration of the cooling device of the present embodiment and an outline of a manufacturing method thereof will be described.

  In FIG. 1, sectional drawing of the cooling device in 1st Embodiment of this invention is shown. In addition, the vertical direction in the figure is the vertical direction of the cooling device 100.

  The cooling device 100 cools the heating element 10 such as a semiconductor element, and as shown in FIG. 1, a liquid-phase refrigerant is stored inside, and a refrigerant tank 110 in which the heating element 10 is installed on the outer surface. And a heat dissipating part 120 that returns the refrigerant vaporized by the heat of the heating element 10 to the refrigerant tank 110 after liquefying.

  The refrigerant tank 110 is, for example, a flat box-like container, and includes a heat receiving wall 111 as a first wall portion and a heat radiating wall 112 as a second wall portion disposed to face the first wall portion. ing. The heat receiving wall 111 and the heat radiating wall 112 are made of, for example, copper or a copper-based alloy. The heat receiving wall 111 and the heat radiating wall 112 have a flat plate shape and are arranged in parallel to the vertical direction.

  The heating element 10 is installed on the outer surface 113 of the heat receiving wall 111, and the porous member 130 having a large number of pores is installed on the inner surface 114 of the heat receiving wall 111. The heating element 10 is fixed by tightening, for example, a bolt (not shown), and the porous member 130 is fixed by, for example, diffusion bonding or brazing.

  In the present embodiment, the inner surface 114 of the heat receiving wall 11 projects toward the porous member 130 in a region corresponding to the heating element 10, that is, a region having the same height as the installed heating element 10. A plurality of protrusions 115 are provided. The details of the protrusion 115 will be described later.

  The porous member 130 transports a liquid-phase refrigerant to a region corresponding to the heating element 10 by a capillary force, and has a three-dimensional network structure. In the present embodiment, a copper foam metal body having continuous bubbles is used as the porous member 130, and the height of the upper end portion of the porous member 130 is equal to or higher than the height of the upper end portion of the heating element 10. Yes.

  The pores of the porous member 130 are, for example, spherical, the pore diameter of the porous member 130 is 150 μm or less, and the thickness of the porous member 130 is 0.4 mm or more and 1 mm or less. Note that these are optimal as the thickness and pore diameter of the porous member 130, but may be other sizes as long as the effects of the present invention can be obtained.

  The heat radiating unit 120 liquefies the refrigerant by radiating the heat of the gas-phase refrigerant to the outside air. In the present embodiment, the heat radiating portion 120 extends in the horizontal direction, and is between the first and second headers 121 and 122 and the first and second headers 121 and 122 arranged orthogonal to the heat radiating wall 112. And a plurality of heat radiation tubes 123 extending in the vertical direction and communicating with the first and second headers 121 and 122, and heat radiation fins 124 interposed between the heat radiation tubes 123.

  The first and second headers 121 and 122 are attached to the heat radiating wall 112 on both ends of the refrigerant tank 110, that is, on the upper side and the lower side in FIG. 1, and communicate with the internal space of the refrigerant tank 110. Yes. The heat radiating fins 124 are well-known corrugated fins and are used to increase the heat radiating area. The first and second headers 121 and 122, the heat radiating tubes 123, and the heat radiating fins 124 are made of, for example, copper or a copper-based alloy.

  Then, a predetermined amount of the refrigerant is sealed in the evacuated cooling device 100 so that the liquid level of the liquid-phase refrigerant is lower than the installation position of the heating element 10. In this embodiment, the refrigerant | coolant of the grade which the liquid phase refrigerant | coolant fills the bottom part of the refrigerant tank 110, ie, the liquid phase refrigerant | coolant of the 2nd header 122 of the thermal radiation part 120, is enclosed.

  As the refrigerant, for example, water, alcohol, fluorocarbon, or chlorofluorocarbon is used. In addition, when water is used as the refrigerant, the boiling point of water is 100 ° C. at 1 atm. However, since the cooling device 100 is evacuated, the boiling point is 30 to 40 ° C.

  The cooling device 100 having such a configuration is manufactured as follows, for example.

  After fixing the porous member 130 to the inner surface 114 of the heat receiving wall 111 by diffusion bonding, the heat radiating wall 112 is arranged to face the heat receiving wall 111 and the refrigerant tank 110 is assembled.

  On the other hand, the first and second headers 121 and 122, the heat radiating tubes 123 and the heat radiating fins 124 are prepared, and the heat radiating portion 120 is assembled.

  And the cooling device 100 whole is assembled | attached by attaching the 1st, 2nd header 121,122 of the thermal radiation part 120 to the outer surface of the thermal radiation wall 112 of the refrigerant tank 110. FIG.

  Then, the cooling device 100 is manufactured by brazing each member integrally with a brazing material applied to a portion to be joined between the members.

  Instead of diffusion bonding the porous member 130 to the inner surface of the heat receiving wall 111, a brazing material is disposed and temporarily fixed between the porous member 130 and the heat receiving wall 111, and at the time of integral brazing, the heat receiving wall 111 and the porous member 130 are porous. The mass member 130 may be fixed by brazing.

  The heat generating body 10 can be cooled by moving the heat of the refrigerant or the heat generating element by the mechanism described below inside the cooling device having the above-described configuration.

  The liquid-phase refrigerant collected at the bottom of the refrigerant tank 110 is sucked up by the capillary force of the porous member 130 and supplied to a region of the porous member 130 corresponding to the heating element 10.

  On the other hand, the heat generated from the heating element 10 is transmitted to the porous member 130 via the heat receiving wall 111. For this reason, the area | region corresponding to the heat generating body 10 among the porous members 130 and the temperature of its vicinity rise.

  Therefore, when the refrigerant is supplied to the region corresponding to the heating element 10 in the porous member 130, the refrigerant boils or evaporates inside the porous member 130, and the heat of the heating element 10 is generated by the latent heat at that time. Heat is removed. At this time, the vaporized refrigerant, that is, the gas-phase refrigerant, is discharged from the region corresponding to the heating element 10 in the porous member 130 as shown by the broken line arrow in FIG. 1 flows into the header 121 and flows from the first header 121 to the heat radiating tubes 123 in a distributed manner.

  When the gas-phase refrigerant that has flowed into the heat radiating tube 123 flows through the heat radiating tube 123, for example, the liquid-phase refrigerant is cooled and liquefied by receiving cooling air supplied from a blower (not shown). As indicated by the solid line arrow in FIG. 1, the refrigerant flows back from the second header 122 to the refrigerant tank 110.

  In this way, the heat generated from the heating element 10 is transferred to the liquid phase refrigerant to become a gas phase refrigerant, and the gas phase refrigerant is transported to the heat radiating unit 120 and released as condensation latent heat when the refrigerant condenses in the heat radiating unit 120. Then, the heat is radiated to the outside air through the radiation fins 124. That is, the heat generated from the heating element 10 is transmitted to the refrigerant, and is released to the outside air by the heat radiating unit 120, thereby cooling the heating element 10.

  Next, the protrusion 115 will be described. FIG. 2 shows a front view of the heat receiving wall 111 when the heat receiving wall 111 of the refrigerant tank 110 in FIG. 1 is viewed in the direction of the arrow A. 3A and 3B are sectional views of the porous member 130 and the refrigerant tank 110 before and after fixing.

  In the present embodiment, as shown in FIG. 2, for example, the protrusions 115 are arranged at the four corners and the central five places of the region corresponding to the heating element 10 indicated by the broken line in FIG. 2. In the present embodiment, five protrusions 115 are provided, but the number of protrusions 115 can be arbitrarily changed within a range of one or more.

  The protrusion 115 is for partially crushing the porous member 130. That is, when the above-described refrigerant tank 110 is assembled, as shown in FIG. 3A, the heat receiving wall 111 having the inner surface 114 provided with the projecting portion 115 having the height t1 and the entire region have a uniform thickness t2. A porous member 130 is prepared, and the porous member 130 is fixed to the inner surface 114 of the heat receiving wall 111 as shown in FIG. Thereby, the porous member 130 has a structure having a region 131 that is crushed by the protrusion 115 in the thickness direction and has a reduced porosity.

  As shown in FIGS. 3A and 3B, the height t1 of the protrusion 115 is smaller than the thickness t2 of the porous member 130, for example, 1/3 to 1/1 of the thickness t2 of the porous member 130. A range of 2 is preferred. When the height t2 is lower than this range, the amount of crushing of the porous member 130 is reduced. When the height t1 of the protrusion 115 is higher than this range, the mesh structure of the porous member 130 is destroyed. Because.

  Further, in the present embodiment, in order to prevent the mesh structure of the porous member from being damaged when the porous member 130 is crushed by the protruding portion 115, the protruding portion 115 is formed as a cylinder as shown in FIGS. The cross section of the protrusion 115 is circular. As for the shape of the protrusion 115, the cross-sectional shape is elliptical, the shape of the protrusion 115 is conical, or the longitudinal section is trapezoidal and conical from the inner surface 114 toward the tip of the protrusion. It is good also as a taper shape in which a diameter reduces gradually.

  Further, the protruding portion 115 is a part of the heat receiving wall 111 protruding, and is made of the same material as the heat receiving wall 111.

  In the present embodiment, the protrusion 115 is provided as described above, so that the heat receiving wall 111 and the porous member 130 are in contact with each other in the region where the heating element 10 is installed, as compared with the case where the protrusion 115 is not provided. The area can be increased. Further, since the protrusion 115 is made of the same material as the heat receiving wall 111, it has the same thermal conductivity and is not porous. Therefore, the protrusion 115 is more easily diffused than the porous member 130.

  Therefore, due to the presence of the protrusion 115, it is possible to promote the diffusion of heat from the heat receiving wall 111 to the porous member 130 when the heating element 10 generates heat compared to the case where the protrusion 115 is not provided.

  In the present embodiment, when the porous member 130 is fixed to the inner surface 114 of the heat receiving wall 111, the porous member 130 is crushed by the protrusion 115 provided on the heat receiving wall 111, and the thickness of the porous member 130 is increased. By compressing in the direction, a region 131 having a smaller porosity than the uncompressed region is formed in the region of the porous member 130 that faces the protruding portion 115 in the protruding direction of the protruding portion 115. The protruding direction of the protruding portion 115 is the same direction as the thickness t2 direction of the porous member 130.

  In the region 131 where the porosity is small, the ratio of the base metal of the porous member 130 is increased, so that the effective thermal conductivity of the porous member 130 is increased compared to the region where the porosity is not compressed. For this reason, thermal diffusion from the region 131 having a small porosity to the surrounding region is promoted.

  As described above, according to the present embodiment, the region 131 where the porosity of the protrusion 115 and the porous member 130 is small, and the region where the porosity of the heat receiving wall 111, the protrusion 115, and the porous member 130 is small from the heating element 10. Thermal diffusion into the porous member 130 via 131 can be promoted.

  As a result, the region where boiling occurs in the porous member 130 can be expanded, and the cooling performance of the cooling device 100 can be improved.

  In the present embodiment, the protrusion 115 is provided at a position facing the region corresponding to the heating element 10 in the porous member 130, and the region in the porous member 130 that sucks the refrigerant, that is, the heating element 10. Since the protrusion 115 is not provided at a position opposite to the area below the area corresponding to, the liquid-phase refrigerant suction performance due to the presence of the protrusion 115 does not deteriorate. Further, the total area of the region 131 where the porous member 130 is crushed by the protrusion 115 is smaller than the area of the heating element 10. Therefore, even if the protrusion 115 is provided, the gas-phase refrigerant dischargeability from the inside of the porous member 130 does not deteriorate.

  In the present embodiment, the height t1 of the protrusion 115 is made smaller than the thickness t2 of the porous member 130 in order to obtain the heat promotion effect by both the protrusion 115 and the region 131 having a small porosity. However, from the viewpoint of obtaining a heat promoting effect by the protrusion 115, the height t1 of the protrusion 115 may be larger than the thickness t2 of the porous member 130.

  Further, although the protrusion 115 is made of the same material as the heat receiving wall 111, it may be made of a material different from the heat receiving wall 111. However, in this case, from the viewpoint of promoting heat from the heat receiving wall 111 to the porous member 130, it is preferable to use a material having a thermal conductivity equal to or higher than that of the heat receiving wall 111.

(Second Embodiment)
In FIG. 4, sectional drawing of the cooling device in 2nd Embodiment of this invention is shown. FIG. 5 shows a partially enlarged view of the region 200 in FIG. In FIG. 4, the same components as those of the cooling device in FIG.

  The cooling device 100 of the present embodiment has the same basic configuration as that of the cooling device 100 described in the first embodiment. Hereinafter, differences from the first embodiment will be described.

  As shown in FIG. 5, the porous member 130 of the present embodiment includes a surface 132 on the heat receiving wall 111 side, that is, a bonding surface 132 with the heat receiving wall 111, and a porous member 130 in a region corresponding to the heating element 10. The number of pores 133 present on the surface 132 on the heat receiving wall 111 side is greater than the number of pores 133 present inside the porous member 130 when the inside of the tube is compared with the cut surface when cut in parallel with the surface 132. Is also decreasing. For this reason, the porosity of the surface 132 on the heat receiving wall 111 side of the porous member 130 is smaller than the overall porosity of the porous member 130 excluding the surface 132.

  Specifically, the porous member 130 has a thickness t3 of 0.5 mm, the pores 133 have a diameter of around 150 μm, and the entire porosity of the porous member 130 excluding the surface 132 is 90%. The porosity at the surface 132 on the wall 111 side is 35%.

  The porous member 130 having such a structure can be manufactured by the following method. For example, a porous member 130 having a total porosity of 90% is prepared, the surface 132 side of the porous member 130 is heated, and only the surface 132 side of the porous member 130 is melted to fill the pores. Thus, the porosity at the surface 132 of the porous member 130 on the heat receiving wall 111 side can be made lower than in other regions. In this case, the pores are filled with the base material of the porous member 130, but in addition, a bonding material for bonding the porous member 130 and the heat receiving wall 111 to the surface 132 of the porous member 130. By applying and filling the pores with the bonding material, the porosity of the surface 132 of the porous member 130 can be lowered as compared with other regions.

  As described above, the porosity of the surface 132 on the heat receiving wall 111 side of the porous member 130 is made smaller than the porosity of the entire porous member 130, whereby the base material of the porous member 130 with respect to the surface 132 is reduced. Since the existence ratio can be increased, the area of the joint surface between the porous member 130 and the inner surface 114 of the refrigerant tank 110 can be increased as compared with the case where the porosity is uniform throughout the porous member 130.

  As a result, the bonding property between the two can be improved, so that it is possible to promote thermal diffusion from the heating element 10 indicated by the arrow in FIG. 5 to the porous member 130 via the heat receiving wall 111. When the thermal diffusion in the porous member 130 is promoted, the region where boiling occurs in the porous member 130 is expanded, so that the cooling performance of the cooling device 100 is improved.

  Here, FIG. 6 shows a result of investigating the influence of the porosity of the surface 132 of the porous member 130 on the thermal resistance of the refrigerant tank 110. The thickness t3 of the investigated porous member 130 is 0.5 mm, the porosity is 90%, and the pore diameter inside the porous member 130 is around 150 μm. By setting the pore diameter of the porous surface to 130 μm and 200 μm, the area ratio of the pores 133 on the surface 132, that is, the porosity of the surface was changed to 35% and 90%. As can be seen from FIG. 6, when the porosity of the surface 132 is set to 35%, the thermal resistance can be significantly reduced as compared with the case where the porosity is set to 90%. In the present embodiment, the porosity of the entire porous member 130 excluding the surface 132 is 90%, and the porosity of the surface 132 on the heat receiving wall 111 side is 35%. As long as the porosity of the porous member 130 is smaller than the overall porosity of the porous member 130 excluding the surface 132, the porosity may be set to other sizes. However, it is preferable that the porosity of the entire porous member 130 excluding the surface 132 is 80% or more and the porosity on the surface 132 on the heat receiving wall 111 side is 40% or less.

  FIG. 7 shows the results of investigating the influence of the thickness t3 of the porous member 130 on the thermal resistance. FIG. 7 shows the results of the investigation when the porosity of the porous member 130 is 90% and the pore diameter of the surface 132 of the porous member 130 is 110 ± 20 μm. Further, the horizontal axis of FIG. 7 indicates the thickness t3 of the porous member 130, and the thickness t3 becomes thinner toward the left side of the horizontal axis, and the gas-phase refrigerant discharge performance is improved. As the right side of the horizontal axis increases, the thickness t3 increases, and the amount of liquid-phase refrigerant absorbed increases, the surface area within the porous member 130 increases, and the amount of foaming nuclei that become buds at the start of boiling increases. Since there are factors that improve characteristics and factors that deteriorate when the thickness is increased, the thermal resistance has a minimum value at a certain thickness. For this reason, from the viewpoint of achieving both the discharge performance of the gas-phase refrigerant and the suction performance of the liquid-phase refrigerant, the thickness t3 of the porous member 130 has a thermal resistance ratio of 1.5 as shown in FIG. It is preferable to set it to 0.4 mm or more and 1 mm or less so that it may become below.

  In addition, about the result of FIG. 7, the same can be said not only in the present embodiment but also in the first, third to sixth and other embodiments.

(Third embodiment)
In FIG. 8, sectional drawing of the cooling device in 3rd Embodiment of this invention is shown. In FIG. 8, the same code | symbol is attached | subjected to the component similar to the cooling device in FIG. 9 shows a front view of the porous member 130 and the heat receiving portion 111 when the porous member 130 in FIG. 8 is viewed from the direction of the arrow B, and FIG. 10 is a cross-sectional view taken along the line CC in FIG. The figure is shown.

  In the present embodiment, a plurality of cuts 134 are provided in the porous member 130. As shown in FIG. 10, the notch 134 is a region where the porous member is completely removed in the direction of the thickness t4 of the porous member 130, and the depth t5 of the removed region is the thickness t4 of the porous member 130. Is the same area. Therefore, the notch 134 is a space portion that forms a larger space than the pores existing in other regions, and the gas-phase refrigerant is easy to move.

  Further, as shown in FIGS. 8 and 9, the notch 134 is arranged across the upper portion of the region corresponding to the heating element 10 and the region above it. Since the region corresponding to the heating element 10 is basically a region where boiling occurs inside the porous member, by providing a cut 134 at such a position, the gas phase refrigerant generated by boiling can be discharged. It can be improved.

  As a result, the cycle of the entire cooling device 100, that is, the suction of the liquid phase refrigerant in the porous member 130, the vaporization of the refrigerant inside the porous member 130, the discharge of the gas phase refrigerant from the porous member 130, and the heat dissipation The liquefaction of the refrigerant in the section 120 can activate a cycle of moving the heat of the heating element 10 to the outside of the cooling device 100, and the frequency of occurrence of boiling of the refrigerant increases. Performance is improved.

  In consideration of the moving direction of the gas-phase refrigerant, it is preferable that the region where the notch 134 is provided be within a range reaching a region where boiling occurs and a region above the region where boiling occurs. It should be noted that the region where boiling occurs and the range reaching the region above the region where boiling occurs include only the region where boiling occurs in the porous member 130 or only the region above the region where boiling occurs. It is.

  The width 134a of the notch 134 is preferably about 1 to 4 times the thickness t4 of the porous member. If the width 134a is smaller than the thickness t4 of the porous member 130, the effect of promoting the discharge of the gas-phase refrigerant is reduced. If the width 134a is four times or more the thickness t4 of the porous member 130, the inside of the porous member 130 is reduced. This is because the area of the region where boiling occurs is reduced and the cooling performance is lowered.

  Moreover, according to this embodiment, the following effects are acquired.

  The amount of gas-phase refrigerant generated increases in proportion to the amount of heat generated by the heating element 10. However, if the amount of gas-phase refrigerant generated is greater than the amount of liquid-phase refrigerant sucked up, a region where no refrigerant exists in the porous member 130 is generated in the vicinity of the heating element 10 in the porous member 130. For this reason, it becomes impossible to remove heat from the heating element 10 using the latent heat of the refrigerant, and the temperature of the heating element 10 rises rapidly.

  As a countermeasure against this, it is conceivable to increase the suction amount of the refrigerant by increasing the thickness of the porous member 130 or decreasing the pore diameter. The problem that the property deteriorates and the frequency of occurrence of boiling decreases.

  On the other hand, by providing the notches 134 as in the present embodiment, the thickness t4 of the porous member 130 is increased and the pore diameter is reduced without deteriorating the gas-phase refrigerant discharge performance. Is possible. When the thickness t4 is increased, the cross-sectional area when the porous member 130 is cut along a plane parallel to the horizontal direction is increased, and when the pore diameter is reduced, the capillary force is increased. As a result, it is possible to increase the suction amount of the liquid phase refrigerant. By increasing the suction amount of the liquid-phase refrigerant, the porous member 130 has a sufficient amount in the porous member 130 even in a region where the heat generation amount of the heating element 10 such as a region corresponding to the heating element 10 increases. An amount of refrigerant can be supplied. Therefore, according to the present embodiment, it is possible to improve the cooling performance of the cooling device 100 when the heat generation amount of the heating element 10 is large.

  Further, in order to generate boiling of the liquid-phase refrigerant inside the porous member 130, a cavity and minute scratches (hereinafter referred to as foaming nuclei) in which steam exists are required on the heat transfer surface. And as the area of the heat transfer surface increases, the probability and amount of foam nuclei increase, so increasing the thickness of the porous member 130 increases the surface area in the porous member. And the amount of foam nuclei can be increased. As a result, boiling can be easily generated even when the heat generation amount of the heating element 10 is small.

  However, the greater the thickness of the porous member 130, the worse the gas-phase refrigerant discharge performance.

  On the other hand, by providing the notches 134 as in the present embodiment, the thickness t4 of the porous member 130 can be increased without deteriorating the vapor discharge performance, and the surface area in the porous member 130 can be increased. Can be increased. As the surface area increases, the amount of foam nuclei that become buds at the start of boiling increases in the porous member. When the amount of foam nuclei increases, boiling easily occurs even in a region where the amount of heat generation is small, such as a peripheral region of the porous member 130 corresponding to the heating element 10. As a result, even when the heat generation amount of the heating element 10 is small, it is possible to maintain high cooling performance using latent heat.

(Fourth embodiment)
In FIG. 11, sectional drawing of the cooling device in 4th Embodiment of this invention is shown. FIG. 11 is a diagram corresponding to FIG. 10, and components similar to those in FIG. 10 are denoted by the same reference numerals as in FIG. 10.

  In the present embodiment, a plurality of grooves 135 are provided on the surface 137 opposite to the bonding surface 136 with the heat receiving wall 111 of the porous member 130 instead of the notches 134 described in the third embodiment. Here, the groove 135 means that the porous member is partially removed from the surface 137 of the porous member 130, and the removed depth t6 is smaller than the thickness t4 of the porous member 130.

  As a means for forming the groove 135, a means for partially removing the porous member by cutting or a means for partially compressing the porous member can be employed. Further, the width 135a of the groove 135 is preferably about 1 to 4 times the thickness t4 of the porous member, similarly to the width 134a of the cut 134.

  Also in this embodiment, since the groove 135 is a region having a larger gap than the pores of the porous member 130 and the gas-phase refrigerant is easily moved, the same effect as in the third embodiment can be obtained. .

(Fifth embodiment)
In FIG. 12, sectional drawing of the cooling device in 5th Embodiment of this invention is shown. FIG. 12 is a diagram corresponding to FIGS. 10 and 11, and components similar to those in FIGS. 10 and 11 are denoted by the same reference numerals as those in FIGS. 10 and 11.

  This embodiment is a combination of the third embodiment and the fourth embodiment. That is, in this embodiment, both the cuts 134 and the grooves 135 are mixed in the porous member 130. Even if it does in this way, the effect similar to 3rd Embodiment is acquired.

(Sixth embodiment)
In FIG. 13, the perspective view of the cooling device in 6th Embodiment of this invention is shown. Moreover, FIG. 14 shows a D arrow view of the heat dissipation part in FIG. 13, and FIG. 15 shows a cross-sectional view taken along line EE in FIG.

  As shown in FIG. 13, the cooling device 100 according to the present embodiment includes a refrigerant tank 110 having a heat generating body 10 fixed to the outer surface and a heat radiating unit 220.

  As shown in FIG. 14, the heat dissipating unit 220 has a configuration in which heat dissipating fins 221 and condensing tubes 222 are alternately stacked.

  As shown in FIG. 15, the refrigerant tank 110 includes a heat receiving wall 111 and a heat radiating wall 112, as in the first embodiment, and a porous member 130 is installed on the inner surface of the heat receiving wall 111.

  Furthermore, the cooling device 100 includes an upper flow path 223 and a lower flow path 224 as a refrigerant path that allows the refrigerant tank 110 and the heat radiation unit 220 to communicate with each other.

  The upper flow path 223 is a flow path that connects the upper part of the condensing tube 222 and a region of the porous member 130 where boiling occurs, that is, a region corresponding to the heating element 10. The upper part of the heat radiating part 220 is a part located above the lower end of the region corresponding to the heating element 10 in the porous member 130. The end of the upper flow path 223 on the heat radiation part 220 side is the upper end 223a, the end of the upper flow path 223 on the refrigerant tank 110 side is the lower end 223b, and the liquid refrigerant flows from the upper end 223a toward the lower end 223b. It is inclined to. Further, the upper end 223 a of the upper flow path 223 is positioned inside the condensate hall 221, and the lower end 223 b of the upper flow path 223 is in contact with the porous member 130.

  Thereby, in this embodiment, the gaseous-phase refrigerant | coolant vaporized in the area | region corresponding to the heat generating body 10 among the porous members 130 is the heat radiating part 220 via the upper flow path 223 like the broken-line arrow in FIG. A part of the liquid-phase refrigerant that has flowed through the heat dissipation section 220 and condensed above the heat radiating section 220 passes through the upper flow path 223 and corresponds to the heating element 10 in the porous member 130 as indicated by the solid line arrow in FIG. It has come to flow into.

  The lower flow path 224 is a flow path connecting the lower part of the refrigerant tank 110 and the lower part of the heat radiating part 220, and the liquid phase refrigerant is transferred from the heat radiating part 220 to the refrigerant tank 110 via the lower flow path 224. Moving.

  As described above, in the present embodiment, a part of the refrigerant condensed at the upper part of the condenser tube 222 of the heat radiating unit 220 is directly passed through the upper flow path 223 to a region where boiling occurs in the porous member 130. It comes to supply.

  Thereby, the liquid-phase refrigerant condensed in the heat radiating section 220 is sucked up by the porous member 130 from the lower flow path 224 via the bottom of the refrigerant tank 110, and corresponds to the heating element 10 in the porous member 130. The moving distance of the liquid-phase refrigerant can be shortened as compared with the case where the liquid-phase refrigerant is supplied to the area to be operated. As a result, the supply speed of the liquid-phase refrigerant into the porous member 130 can be increased, and when the amount of heat generated by the heating element 10 increases rapidly, the porous member 130 is moved to a region corresponding to the heating element 10. A sufficient amount of refrigerant can be supplied, that is, the responsiveness of the cooling device 100 can be improved.

  Although not shown, by providing a porous member inside the upper flow path 223, the supply speed of the liquid-phase refrigerant can be further increased by the capillary force of the porous member. At this time, the porous member provided in the upper flow path 223 is different from the porous member 130 provided in the refrigerant tank 110.

(Other embodiments)
(1) In the third to fifth embodiments, the cuts 134 and the grooves 135 are provided in the porous member 130, but instead of these, a region having a large pore diameter may be locally provided.

  (2) In the first to fifth embodiments, the refrigerant tank 110 is arranged with the heat receiving wall 111 and the heat radiating wall 112 parallel to the vertical direction, but the refrigerant tank 110 is arranged so that the heat radiating unit 120 faces upward. It is also possible to use the cooling device 100 in a state where the heat receiving wall 111 and the heat radiating wall 112 are horizontal and the heating element 10 is installed on the outer surface of the heat receiving wall 111 which is the bottom surface of the refrigerant tank 110.

  (3) In the cooling device 100 in the first to fifth embodiments, the configuration of the heat radiating unit 120 can be arbitrarily changed.

  (4) In each of the above-described embodiments, a copper foam metal body is used as the porous member 130. However, as the porous member 130, a foam metal body made of another metal may be used. Bonded metal, wire mesh, metal felt or the like may be employed.

  Further, in each of the above-described embodiments, the porous member 130 has the same size as the heat receiving wall 111 as shown in FIG. 1, for example, but corresponds to the heating element 10 at least from the region in contact with the liquid phase refrigerant. The size of the porous member 130 can be arbitrarily changed as long as the size reaches the region to be processed.

It is sectional drawing of the cooling device in 1st Embodiment of this invention. FIG. 2 is a front view of the heat receiving wall 111 when the heat receiving wall 111 of the refrigerant tank 110 in FIG. 1 is viewed in the direction of arrow A. (A), (b) is sectional drawing of the porous member 130 and the refrigerant tank 110 before and behind fixation. It is sectional drawing of the cooling device in 2nd Embodiment of this invention. It is the elements on larger scale of the area | region 200 in FIG. 6 is a graph showing the results of investigating the influence of the porosity of the surface 132 of the porous member 130 on the thermal resistance of the refrigerant tank 110. It is a graph which shows the investigation result of the influence which thickness t3 of the porous member 130 has on thermal resistance. It is sectional drawing of the cooling device in 3rd Embodiment of this invention. It is a front view of the porous member 130 and the heat receiving part 111 when the porous member 130 in FIG. 8 is seen from the arrow B direction. It is CC sectional view taken on the line in FIG. It is sectional drawing of the cooling device in 4th Embodiment of this invention. It is sectional drawing of the cooling device in 5th Embodiment of this invention. It is sectional drawing of the cooling device in 6th Embodiment of this invention. It is D arrow line view of the thermal radiation part in FIG. It is the EE sectional view taken on the line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Heat generating body, 100 ... Cooling device, 110 ... Refrigerant tank, 111 ... Heat receiving wall,
112 ... Radiating wall, 120, 220 ... Radiating part,
121 ... 1st header, 122 ... 2nd header, 123 ... Radiation tube,
124 ... radiating fins, 130 ... porous member.

Claims (7)

A liquid-phase refrigerant is stored therein, a heating element (10) is installed on the outer surface of the wall (111), and a porous network having a large number of pores on the inner surface (114) of the wall (111). A refrigerant tank (110) for transporting a liquid phase refrigerant to a region corresponding to the heating element (10) by a capillary force of the porous member (130),
In the cooling device (100), comprising a heat dissipating part (120) that returns the refrigerant tank (110) after liquefying the refrigerant vaporized by the heat of the heating element (10),
The refrigerant tank (110) has a protrusion (115) protruding toward the porous member (130) in a region corresponding to the heating element (10) in the inner surface (114) of the wall (111). And a cooling device. The protrusion (115) has a height (t1) from the inner surface (114) of the wall portion smaller than the thickness (t2) of the porous member (130),
The porous member (130) is opposed to the protrusion (115) by compressing a portion of the porous member (130) facing the protrusion (115) in the protrusion direction of the protrusion (115) by the protrusion. The cooling device according to claim 1, wherein the cooling device has a region (131) in which the porosity is smaller than that of the non-existing portion. A liquid-phase refrigerant is stored therein, a heating element (10) is installed on the outer surface of the wall (111), and a porous network having a large number of pores on the inner surface (114) of the wall (111). A refrigerant tank (110) for transporting a liquid phase refrigerant to a region corresponding to the heating element (10) by a capillary force of the porous member (130),
In the cooling device (100), comprising a heat dissipating part (120) that returns the refrigerant tank (110) after liquefying the refrigerant vaporized by the heat of the heating element (10),
The porous member (130) is a region corresponding to the heating element (10) in the porous member, and the porosity on the wall (111) side surface (132) is the surface (132). A cooling device, wherein the porosity is smaller than the porosity in the porous member (130) excluding. A liquid-phase refrigerant is stored therein, a heating element (10) is installed on the outer surface of the wall (111), and a porous network having a large number of pores on the inner surface (114) of the wall (111). A refrigerant tank (110) for transporting a liquid phase refrigerant to a region corresponding to the heating element (10) by a capillary force of the porous member (130),
In the cooling device (100), comprising a heat dissipating part (120) that returns the refrigerant tank (110) after liquefying the refrigerant vaporized by the heat of the heating element (10),
The porous member (130) is a space formed by being partially removed within a range extending to a region corresponding to the heating element (10) and a region higher than the region. A cooling device having a space (134, 135) constituting the space larger than the pores existing in the region. The space portion has a depth (t5) of a region from which the porous member (130) is partially removed is the same notch (134) as the thickness (t4) of the porous member (130). The cooling device according to claim 4. The space portion is a portion obtained by partially removing the porous member from the surface (137) opposite to the surface in contact with the wall portion (111) of the porous member (130). The cooling device according to claim 4 or 5, wherein the depth (t6) of the portion is a groove (135) smaller than the thickness (t4) of the porous member (130). A liquid-phase refrigerant is stored therein, a heating element (10) is installed on the outer surface of the wall (111), and a porous network having a large number of pores on the inner surface (114) of the wall (111). A refrigerant tank (110) for transporting a liquid phase refrigerant to a region corresponding to the heating element (10) by a capillary force of the porous member (130),
In the cooling device (100) comprising a heat radiating section (220) that returns the refrigerant tank (110) after liquefying the refrigerant vaporized by the heat of the heating element (10),
A refrigerant passage (223) that communicates the heat radiating section (220) and a region corresponding to the heating element (10) in the porous member (130) in the refrigerant tank (110);
One end (223b) of the refrigerant passage (223) is in contact with a region of the porous member (130) corresponding to the heating element (10), and the other end (223a) of the refrigerant passage (223) is , Located inside the heat dissipating part (220),
A part of the refrigerant condensed in the heat radiating part (220) is supplied to a region of the porous member (130) corresponding to the heating element (10) through the refrigerant passage (223). The cooling device characterized by becoming.

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