JP2007081375A - Cooling system - Google Patents

Abstract

[PROBLEMS] To reduce the pressure loss without significantly impairing the heat transfer performance, thereby enabling a higher cooling efficiency as a whole without using a powerful pump, thereby keeping the temperature of the heat generating electronic component low. An object of the present invention is to provide a cooling device capable of performing the above.
SOLUTION: 10 is a base plate to be brought into contact with a heat generating electronic component 4, 11 is a plurality of heat transfer fins provided integrally with the base plate 10, 12 is an inlet through which refrigerant flows from an external pipe 8, and 13 is external to the refrigerant. It is an outlet to go out to the piping. The heat transfer fin 11 has a cutout portion 11a in which an upper corner portion on the refrigerant inlet 12 side is cut out in an arc shape, and thereby, a portion with little contribution to heat transfer is deleted. Pressure loss can be reduced without significantly degrading heat transfer performance.
[Selection] Figure 2

Description

  The present invention is a cooling system that cools a heat-generating semiconductor such as a microprocessing unit (hereinafter abbreviated as MPU) used in a personal computer or the like, or an electronic component having other heat-generating parts by circulation of refrigerant or heat absorption by phase change. It relates to the device.

  In recent years, in electronic devices, the contact temperature of each electronic component has been reduced for the normal operation of the electronic component against the increase in heat generation due to higher integration of electronic components such as semiconductors and higher operating clock frequencies. How to keep within the operating temperature range has become a major issue. For this reason, it is not sufficient to perform air cooling with a heat sink as in the conventional case, and a more efficient cooling device is indispensable. Thus, as such a cooling device, the present applicant has proposed a cooling device that efficiently cools the generated electronic components by circulating the refrigerant (Patent Document 1).

  Hereinafter, a conventional cooling device that circulates and cools the refrigerant and a cooling device that uses an endothermic action due to the phase change of the refrigerant will be described.

  In the configuration diagram of the electronic device having the conventional cooling device of FIG. 10, 101 is a housing of a personal computer as an electronic device equipped with the cooling device, 103 is in contact with the heating element to constitute the cooling device, and exchanges heat. The heat exchanging means 104 is a heat generating electronic component such as an MPU. Reference numeral 105 denotes a substrate on which the heat generating electronic component 104 is mounted, 107 denotes a radiator that is provided on the inner side surface of the housing 101 and dissipates the heat of the refrigerant received from the heat generating electronic component 104 to the outside, and 108 denotes a heat exchanging means 103 and a radiator 107. And a closed pipe for circulating the refrigerant. Reference numeral 109 denotes a pressurizing pump that pumps and circulates the refrigerant.

  A heat conductive grease (not shown) is applied to the contact surface between the heat generating electronic component 104 and the heat exchanging means 103 to reduce the contact heat resistance at the contact surface.

  As the refrigerant circulating in the pipe 108, an antifreeze liquid such as an ethylene glycol aqueous solution or a propylene glycol aqueous solution is suitable, and further, as described later, copper or the like is used as a material for the internal components of the heat exchange means 103. It is desirable to add.

  The radiator 107 is made of a material having high heat conductivity and good heat dissipation, for example, a thin plate material such as copper or aluminum, and a refrigerant passage and a reserve tank are formed therein. Further, a fan may be provided to increase the cooling effect by forcibly applying air to the radiator 107 for cooling.

  The piping 108 is made of a rubber tube such as a flexible rubber having a low gas permeability, for example, butyl rubber, in order to ensure flexibility in piping layout.

  The heat exchanging means 103 is composed of a metal part such as aluminum or copper having excellent heat conductivity and a resin part that does not leak the refrigerant to the outside and has a strength that can withstand a fixed stress given from the outside.

  FIG. 11 is a sectional view of heat exchange means of a conventional cooling device. 110 is a base plate to be brought into contact with the heat generating electronic component 104, 131 is a plurality of heat transfer fins provided integrally with the base plate 110, 112 is an inlet through which refrigerant flows in from the external pipe 108, 113 is refrigerant in the external pipe 108 It is an outlet for going out. Reference numeral 114 denotes a case in which the base plate 110 is pressed against the heat generating electronic component 104 with an appropriate force given from the outside by a member not shown. Although not shown in this figure, the base plate 110 is integrally provided with a plurality of heat transfer fins 131 at an arbitrary interval.

  The refrigerant pressurized by the pressurizing pump 109 has a downward vector when it enters from the inlet 112. The vector is deflected in the horizontal direction due to the presence of the base plate 110 and the heat transfer fins 131. Thus, the refrigerant is guided to the gap between the plurality of heat transfer fins 131 arranged side by side. On the other hand, the temperature of the base plate 110 rises due to the heat transferred from the interface of the heat generating electronic component 104, and the surface temperature of the heat transfer fins 131 also rises. The refrigerant in contact with the base plate 110 and the heat transfer fins 131 flows between the heat transfer fins 131 while receiving an amount of heat proportional to the temperature difference between them, is guided to the outlet 113 located downstream, and flows out to the external pipe 108. To do. Thereafter, the refrigerant is led to the radiator 107 through the pipe 108, and the amount of heat received here is released to the air outside the system.

  FIG. 12 is a schematic perspective view of a base plate and heat transfer fins of a conventional cooling device.

  In FIG. 12, a plurality of heat transfer fins 131 are formed by forming gaps by wire electric discharge machining from a metal lump typically represented by integral copper. In this method, there are no gaps and other members that are disadvantageous for heat conduction between the base plate 110 and the heat transfer fins 131, so that deterioration of heat exchange characteristics can be prevented, but mass productivity is good. Absent.

  Therefore, regardless of such processing, a method suitable for mass production, in which thin plates obtained by pressing or the like are arranged with an appropriate gap therebetween and fixed to the base plate 110 with silver brazing or the like, and There is also a method of forming the heat transfer fins 131 by cutting and raising the surface of the base plate 110 with a blade-like tool.

The above is a description of the conventional cooling device. Further, the pipe, the heat receiving part, and the heat radiating part are made of a metal such as copper so that the air can be kept sufficiently airtight to the outside. There has also been proposed a cooling system that encloses a certain amount of water or an alternative chlorofluorocarbon such as HFC-134a and applies heat transfer by phase change of the refrigerant. This cooling device is substantially the same as the conventional cooling device described above except that the internal pressure is kept lower than the normal pressure or a refrigerant having a low boiling point is used. This cooling device is the same as a heat pipe in that a phase-changeable liquid is enclosed in an airtight container and heat transfer is performed by phase change, but the circulation rate is increased by forcibly circulating the refrigerant by a pump. This cooling device that increases the heat exchange performance is called a forced circulation heat pipe. Since the internal pressure of this cooling device is low, the internal refrigerant is likely to evaporate at a low temperature. Therefore, unlike the cooling device described above, the refrigerant guided to the heat exchange means receives heat from the heat transfer fins by evaporating all or part of it and taking away the heat of vaporization. The refrigerant that has evaporated into vapor flows out from the heat exchanging means to the piping, and is then guided to the radiator by the piping, and condenses by touching the inner wall of the low-temperature radiator. The amount of heat received at this time is released as condensation heat. This heat is released to the air outside the system through a radiator as in the cooling device.
JP 2005-327776 A

  Considering general heat transfer, in order to transfer the heat of the heat generating electronic component 104 to the refrigerant with higher efficiency, as described above, the amount of heat transfer is proportional to the temperature difference, so that it is provided on the base plate 110 in contact with the refrigerant. The surface temperature of the heat transfer fin 131 is kept as high as possible as close as possible to the heat generating electronic component 104. In other words, the temperature difference between the refrigerant and the heat transfer fin 131 is kept large, and the surface area of the heat transfer fin 131 in contact with the refrigerant is increased. It is necessary to secure.

  Here, the heat transfer fin 131 of the conventional cooling device will be verified. The heat transfer surface that is the surface through which heat is transmitted from the heat generating electronic component 104 to the base plate 110 is only the contact surface with the heat generating electronic component 104. Therefore, the surface temperature of the base plate 110 and the heat transfer fin 131 has a distribution proportional to the heat transfer distance from the contact surface.

  FIG. 13 is a temperature distribution diagram of the conventional base plate 100 and heat transfer fins 131 obtained by thermal fluid simulation. In FIG. 13, the flow of the refrigerant is in the direction from left to right, and this temperature distribution is the center of the simulation model divided into two by a plane passing through the center of the contact surface and perpendicular to the contact surface and parallel to the refrigerant flow. A cross section is shown. In the figure, the region shown in white is close to the heat source, so the temperature is high, and in the other regions, as shown in the legend in the figure, the temperature decreases in the order of light shading and dark shading adjacent to it. Further, the hatched portion located above the fin indicates a region where the temperature difference is within 2 ° C. with respect to the incoming refrigerant temperature in the simulation result.

  The lower half has a concentric temperature distribution centered on a part of the bottom of the base plate 110, and it can be seen that the temperature distribution reflects the heat transfer surface of the bottom of the base plate 110. In the upper half, due to the flow of the refrigerant, a low temperature portion exists in a quadrant shape centering on the upper end of the front edge of the heat transfer fin 131 with respect to the flow of the refrigerant. As described above, this low temperature portion is substantially equal to the temperature of the refrigerant flowing in. That is, this portion does not contribute to heat exchange, and heat transfer in this plane is performed in other portions. Although the heat transfer area is limited in this manner on the surface of the heat transfer fin 131, such distribution is the same in the vertical direction in the figure, and the temperature rapidly decreases as the distance from the heat transfer surface at the bottom of the base plate 110 increases. To do. In other words, the heat-exchangeable region is a region in the radiation surface centered on the heat transfer surface, so the main purpose is to increase the heat transfer area in this region, and the thickness and fin spacing of the heat transfer fins 131 are minimized. It will be sufficient to make it smaller.

  However, in reality, fluid resistance is generated on the surface of the heat transfer fin 131 by the shear stress caused by the viscosity of the refrigerant passing between the heat transfer fins 131. The fluid resistance due to the shear stress is called pressure loss. In the same pump, the generated pressure and the flow rate at that time are uniquely determined. Therefore, when the pressure loss increases, the flow rate decreases. The state of the region occupied by the refrigerant with respect to the region occupied by the heat transfer fin 131 in a state where the thickness of the heat transfer fin 131 and the interval between the heat transfer fins 131 are reduced to the minimum, in other words, in a cross section perpendicular to the flow direction of the refrigerant. As the ratio decreases, this pressure loss increases. In addition, when the length of the heat transfer fins 131 becomes longer in a cross section parallel to the refrigerant flow direction, in other words, when the area of the heat transfer fins 131 that contacts the refrigerant increases, the pressure loss increases in proportion to the gap between the fins. The flow rate of the refrigerant passing therethrough will be reduced. The flow rate and heat transfer efficiency are generally proportional not only to the heat transfer part but also to the heat release part. To improve the system performance, it is necessary to secure a powerful pump that can overcome pressure loss and flow a large amount of refrigerant. It becomes. However, this leads to an increase in the size of the pump, which is against the demand for cost reduction and noise reduction of the apparatus, and is becoming difficult to realize.

  Similarly, in a cooling device using a forced circulation heat pipe that transfers heat with phase change, if the refrigerant that changes from the liquid phase to the gas phase due to evaporation is a part, most of the refrigerant remains in the liquid phase. Passes between heat transfer fins. For this reason, similarly to the cooling device, a pressure loss that increases in proportion to the area of the heat transfer fin 131 that contacts the refrigerant occurs, and the flow rate of the refrigerant that passes between the fins decreases.

  The present invention solves the above-mentioned problems, and by reducing the pressure loss without significantly impairing the heat transfer performance, the cooling efficiency can be further improved as a whole without using a powerful pump. An object of the present invention is to provide a cooling device capable of keeping the temperature of a heat generating electronic component low.

  In the cooling device of the present invention, a closed pipe for circulating the refrigerant is provided with a refrigerant pump, a heat radiating device, and a heat exchanging means, and the heat exchanging means is brought into contact with a heat generating electronic component so as to contact the refrigerant inside the closed pipe. A cooling device that removes heat from the heat generating electronic component by heat exchange action and dissipates heat from the heat dissipation device, wherein the heat exchange means includes a plurality of heat transfer fins, and the heat transfer fins are on the refrigerant inflow side. Is formed so as to be lower than the height on the refrigerant outflow side.

  According to the cooling device of the present invention, since the heat transfer fin is formed so that the refrigerant inflow side is lower than the refrigerant outflow side, the pressure loss can be reduced without reducing the heat exchange performance in the heat exchange means. As a whole, the cooling efficiency is increased, and the temperature of the heat generating electronic component can be kept low.

  According to a first aspect of the present application, a refrigerant pump, a radiator, and a heat exchanger are provided in a closed pipe that circulates a refrigerant, and the heat exchanger receives heat from an electronic component and circulates through the refrigerant pump. The heat exchanger includes a plurality of heat transfer fins in a housing having a refrigerant inlet and outlet, and the heat transfer fin is a refrigerant inlet. The cooling device is characterized in that the height on the side is lower than the height on the outlet side of the refrigerant, and this configuration contributes to heat transfer generated on the refrigerant inflow side. It is possible to reduce the portion where there is a small amount of heat, and thereby reduce the pressure loss of the heat exchange portion.

  The second invention of the present application is characterized in that the refrigerant inlet side portion of the heat transfer fin is formed to have a predetermined length and a continuous height from the inlet side end to the center portion. The cooling device according to claim 1, wherein such a configuration prevents fluid resistance due to the viscosity of the refrigerant and reduces pressure loss in the heat exchange part without reducing the effective heat transfer area. can do. In addition, an effective heat transfer area shows the area | region which can contact a refrigerant | coolant and can exchange heat among the surface areas of a heat transfer fin.

  In the third invention of the present application, the cross-sectional area of the heat transfer fin in the flow direction of the refrigerant is included in a predetermined width of the heat transfer fin from the side heat transfer fin along the flow of the refrigerant to the heat transfer fin in the center. The cooling device according to claim 1, wherein the heat transfer fin is continuously formed to have a large cross-sectional area. Since the heat transfer fins each formed in a shape that minimizes the pressure loss are arranged, the pressure loss of the heat exchange portion can be reduced without reducing the effective heat transfer area.

  According to a fourth aspect of the present invention, the cross-sectional area of the heat transfer fin in the flow direction of the refrigerant is included in a predetermined width of the heat transfer fin from the side heat transfer fin along the flow of the refrigerant to the heat transfer fin in the center. The heat transfer fins are formed so that the cross-sectional area continuously increases, and the height of each heat transfer fin is continuously increased from the refrigerant inlet side end to the center of the heat transfer fin. The cooling device according to claim 1, wherein the heat transfer is formed in such a configuration that the pressure loss is minimized in the refrigerant flow path. Since the fins are arranged, the pressure loss of the heat exchange part can be reduced without reducing the effective heat transfer area.

  5th invention of this application is a cooling device of any one of Claims 1 thru | or 4 characterized by the heat exchanger performing a heat exchange by a phase change of a refrigerant | coolant, Such a structure As a result, heat transfer fins, each formed in a shape that minimizes the pressure loss, are arranged in the refrigerant flow path, so that the pressure loss in the heat exchange portion is reduced without reducing the effective heat transfer area. be able to.

(Embodiment 1)
The heat exchange means of the cooling device in Embodiment 1 of the present invention will be described.

  FIG. 1 is a configuration diagram of an electronic apparatus including a cooling device according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view of heat exchange means of the cooling device according to Embodiment 1 of the present invention, and FIG. FIG. 4 is a schematic perspective cross-sectional view of the base plate and the heat transfer fin of the cooling device according to the first embodiment, and FIG. 4 is a temperature distribution diagram of the base plate and the heat transfer fin of the cooling device according to the first embodiment of the present invention obtained by thermal fluid simulation. It is.

  In FIG. 1, 1 is a housing of a personal computer as an electronic device equipped with a cooling device, 3 is a heat exchange means for exchanging heat in contact with a heating element to constitute the cooling device, and 4 is a heat generating electronic component such as an MPU. It is. 5 is a substrate on which the heat generating electronic component 4 is mounted, 7 is a radiator provided on the inner side surface of the housing 1 to dissipate the heat of the refrigerant received from the heat generating electronic component 4 to the outside, and 8 is a heat exchanging means 3 and a radiator 7. And a closed pipe for circulating the refrigerant. Reference numeral 9 denotes a pressurizing pump for pumping and circulating the refrigerant.

  A heat conductive grease (not shown) is applied to the contact surface between the heat generating electronic component 4 and the heat exchanging means 3 to reduce the contact heat resistance at the contact surface.

  As the refrigerant circulating in the pipe 8, an antifreeze solution such as an ethylene glycol aqueous solution or a propylene glycol aqueous solution is suitable, and further, as described later, copper or the like is used as a material for internal components of the heat exchange means 3, so that an anticorrosive additive is used. It is desirable to add.

  The radiator 7 is made of a material having high heat conductivity and good heat dissipation, for example, a thin plate material such as copper or aluminum, and has a refrigerant passage and a reserve tank formed therein. Further, a fan may be provided to increase the cooling effect by forcibly applying air to the radiator 7 for cooling.

  The pipe 8 is composed of a rubber tube such as a rubber having flexibility and low gas permeability, for example, butyl rubber, in order to secure a degree of freedom of the pipe layout.

  The heat exchanging means 3 is composed of a metal part such as aluminum or copper having excellent heat conductivity and a resin part that does not leak the refrigerant to the outside and has a strength that can withstand a fixed stress given from the outside.

  Next, the internal configuration of the heat exchange means 3 will be described with reference to FIG.

  This cross-sectional view is taken along the A-A ′ cross section in FIG. 1, and the white arrow in the figure represents the direction of the refrigerant flow.

  10 is a base plate to be brought into contact with the heat generating electronic component 4, 11 is a plurality of heat transfer fins provided integrally with the base plate 10, 12 is an inflow port through which refrigerant flows in from the external pipe 8, and 13 is in the external pipe 8 It is an outlet for going out. Reference numeral 14 denotes a case in which the base plate 10 is pressed against the heat generating electronic component 4 with an appropriate force given from outside by a member (not shown). Although not shown in this figure, the base plate 10 is integrally provided with a plurality of heat transfer fins 11 at an arbitrary interval.

  Since the actual shape of the case 14 is complicated and a certain degree of heat resistance is required, it is preferable to manufacture the case 14 by resin molding such as polyphenylene sulfide (PPS) or polyphenylene ether (PPE). The thermal conductivity of these resin parts is very small compared to general metals. Therefore, heat transfer to the outside through this component is negligibly small. That is, the movement of heat from the heat generating electronic component 4 is in the order of the base plate 10, the heat transfer fins 11, and the refrigerant. Actually, since there is a minute gap between the heat generating electronic component 4 and the base plate 10 due to the surface roughness, for example, heat in which a fine powder such as aluminum having excellent thermal conductivity is mixed in a silicon base material. It is desirable to apply a thin conductive grease.

  In FIG. 3, the base plate 10 that contacts the heat generating electronic component 4 is a plate having a rectangular shape in plan view, and is made of a metal material such as copper or aluminum having high heat conductivity and good heat dissipation. It is comprised by the processing method of the combination.

  The heat transfer fin 11 is a plate having a cutout portion 11a in which an upper corner portion on the refrigerant inlet 12 side is cut out in an arc shape, and a plurality of heat transfer fins 11 having the same shape are slightly opened. In this state, it is fixed so as to be perpendicular to the base plate 10. The heat transfer fins 11 are made of a metal material such as copper or aluminum having high heat conductivity and good heat dissipation. As a method for fixing the heat transfer fin 11 to the base plate 10, brazing, soldering, welding, or the like can be considered. Ideally, however, for example, from an integral metal block to wire electric discharge machining as shown in FIG. Forming integrally with the base plate 10 by processing according to representative cutting is preferable because the thermal resistance is minimized. In this case, first, the outer shape of the heat transfer fin 11 is formed by milling or the like, and then wire electric discharge machining is performed to form a plurality of heat transfer fins 11.

  In FIG. 4, as in FIG. 13, the white area is close to the heat source, so the temperature is high. In the other areas, as shown in the legend in FIG. The temperature decreases in the order of multiplication. Further, the hatched portion located above the fin indicates a region where the temperature difference is within 2 ° C. with respect to the incoming refrigerant temperature in the simulation result.

  2, the refrigerant pressurized by the pressurizing pump 9 provided outside the heat exchanging means 3 passes through the gap between the heat transfer fins 11 due to the pressure difference between the inflow port 12 and the outflow port 13 in the direction indicated by the white arrow. To flow through. At this time, the refrigerant takes heat away from the liquid contact surface of the base plate 10 and the heat transfer fins 11. As described above, if the gap between the heat transfer fins 11 is narrowed in order to increase the heat exchange area, the pressure loss increases, and the heat exchange efficiency is lowered as long as the same pressure pump 9 is used. In the present embodiment, an arc-shaped cutout portion 11 a is provided at the upper corner portion on the inflow side of the heat transfer fin 11, and the presence of the cutout portion 11 a allows the refrigerant to contact the heat transfer fin 11. The liquid area is reduced. The shape of the cutout portion 11a substantially coincides with the portion occupied by the low temperature portion in the conventional heat transfer fin 131 shown in FIG. This low temperature part is a part where the refrigerant flowing in from the inlet 12 first comes into contact with the heat transfer fins 31, and the contact surface temperature here is almost the same as that of the refrigerant and has a distance from the heat source. The amount of heat transmitted through the fins is also small. That is, in this portion, since there is no temperature difference between the refrigerant and the heat transfer fins 31, heat is not transferred, and fluid friction occurs between the refrigerant and the surface of the heat transfer fins 31 and only pressure loss occurs. On the other hand, as described above, the heat transfer fin 11 in the present embodiment has a notch portion 11a formed by notching the upper corner portion on the refrigerant inlet 12 side, which is a portion where fluid friction occurs and pressure loss occurs. As a result, it is possible to reduce the pressure loss while minimizing the decrease in the heat transfer amount. Comparing FIG. 4 and FIG. 13, it can be seen that the low-temperature portion extends to the downstream in this embodiment because the portion corresponding to the conventional low-temperature portion is almost eliminated. This indicates that the pressure loss at the upper portion of the fin is reduced, the flow velocity at the upper portion of the fin is increased, the heat exchange rate is improved, and the temperature is lowered as a result. In addition, as shown in FIG. 4 or FIG. 13, since the high temperature part with good heat exchange efficiency spreads on the radiation surface on the heat transfer surface from the heat generating electronic component 4, it spreads and is distributed downstream by the flow of the refrigerant. When the pressure of the pressurizing pump 9 is reduced to reduce the noise or the pressure-feeding capability is absolutely insufficient, when further lower pressure loss is required, for example, along the isotherm of FIG. If the area of the notch portion 11a of the heat transfer fin 11 is increased until the required pressure loss is obtained, a cooling device in which the deterioration of the heat transfer performance is minimized can be obtained.

(Embodiment 2)
The heat exchange means 3 of the cooling device in Embodiment 2 of this invention is demonstrated.

  FIG. 5 is a temperature distribution perspective view of a conventional heat transfer fin 131 by a thermal fluid simulation. 6 and 7 are schematic perspective sectional views of the base plate 10 and the heat transfer fins 11 of the cooling device according to the second embodiment of the present invention.

  In FIG. 5, a region indicated by white in the drawing is a heat source. As shown in FIG. 5, the region where the temperature is almost equal to that of the refrigerant is the narrowest in the vicinity of the central cross section parallel to the flow of the refrigerant, and is widened toward the end. As described above, this is due to the fact that the heat from the heat generating electronic component 4 expands while maintaining a radiation surface isothermal surface centered on the heat transfer surface. As described above, since the temperature distribution has a three-dimensional structure, the shape of the entire rectangular parallelepiped composed of the plurality of heat transfer fins 21 is three-dimensionally changed in accordance with the three-dimensional structure. If the heat transfer fins 21 are formed in different shapes depending on the positions, low pressure loss can be realized while minimizing the reduction in effective heat transfer area.

  FIG. 6 shows an example in which the heat transfer fin 21 is formed integrally with the base plate 10 from one metal lump by the above-described wire electric discharge machining or the like. First, an outer shape in which a rectangular parallelepiped conforming to a conventional fin shape is integrated with the base plate 10 is formed, and this is formed into a curved surface of A portion in FIG. 6 using a ball end mill or the like, and thereafter FIG. The middle B portion is processed with an end mill or the like, and then the portion that becomes the gap between the heat transfer fins 21 is processed by wire electric discharge machining to form one heat transfer fin 21 each. The shape before wire electric discharge machining can be obtained at a relatively low cost by casting when aluminum is used as the material and by forging when using copper as the material. In addition, in order to form it more inexpensively, a material block having a shape obtained by digging a flat portion obtained by the above-mentioned end milling into a rectangular parallelepiped conforming to the fin shape is formed by casting or casting, and then it is wire-discharge processed to obtain a fin. A shape may be obtained.

  FIG. 7 shows an example in which the heat transfer fin 21 is formed integrally with the base plate 10 from one metal lump by the above-described wire electric discharge machining or the like. First, an outer shape in which a rectangular parallelepiped conforming to the conventional fin shape is integrated with the base plate 10 is formed, and this is formed into a curved surface A in FIG. 7 using a ball end mill or the like, and thereafter FIG. The middle B portion is processed with an end mill or the like, and then the portion that becomes the gap between the heat transfer fins 21 is processed by wire electric discharge machining to form one heat transfer fin 21 each. The shape before wire electric discharge machining can be obtained at a relatively low cost by casting when an aluminum material is used, and by forging when using copper as a material. In addition, in order to form more inexpensively, the fin shape is divided into an arbitrary number of portions from the center portion to the end portion, the average shape of each portion is determined, and the heat transfer fin 21 is created by pressing each shape. Alternatively, each piece may be fixed to the base plate 10 by silver brazing or the like.

(Embodiment 3)
The above is a description of a cooling device in which a low-temperature refrigerant comes into contact with a high-temperature heat transfer surface such as the surface of a heat transfer fin and receives heat there to raise the refrigerant temperature and carry away the heat. In addition to the above, there has been proposed a cooling device that efficiently uses the heat of vaporization accompanying the phase change of the refrigerant from the liquid phase to the gas phase to efficiently transfer heat from a heat source having a higher heat density. For example, when water is used as the refrigerant, in order to transfer heat using the phase change, the pressure at the heat transfer section should be kept low so that the refrigerant evaporates at the required heat transfer fin surface temperature. To. Therefore, in order to maintain the airtightness permanently against the external atmospheric pressure, it is necessary to make special considerations such as welding for joining the parts, and all the members that contact the refrigerant as well as the piping are made of metal such as copper. In addition, it is necessary to consider the components. For example, when the coolant is water, metals such as aluminum that cannot react with the coolant and generate non-condensable gases or organic materials cannot be used as materials for parts that come into contact with liquid. . However, it is needless to say that a material having good thermal conductivity should be used for the heat receiving portion and the liquid contact area should be secured. Therefore, here, if water, which is considered to be the least expensive, is used as the refrigerant, copper is inevitably the best constituent material. Therefore, not only the basic configuration of the cooling device described above, but also the manufacturing method of the heat transfer fins and the like are applied as they are. The heat transfer due to the phase change of the refrigerant is such that the refrigerant cooled below the boiling point by the radiator contacts the heat transfer fins, the part heated above the boiling point boils and evaporates, and a large amount of heat is transferred by the heat of vaporization at that time Deprived of fins. The generated vapor moves upward according to the buoyancy while drifting in the refrigerant in the liquid phase in the form of bubbles. However, at this time, if air bubbles stay between the heat transfer fins, there is a possibility that a dry-out state may occur. The dry-out state is a state in which liquid-phase refrigerant is not supplied to the high-temperature part, and heat transfer is hardly performed here. In order to prevent the bubbles from staying, it is necessary to cause the refrigerant between the fins to flow. In this way, the refrigerant flows with a pump. Some forced circulation type heat pipes change the phase of only a part of the refrigerant circulation amount, and in this type of forced circulation type heat pipe as well, pressure loss occurs when generating a refrigerant flow in which bubbles are mixed. This causes problems such as insufficient pump capacity. That is, by taking the same means as described above, the pressure loss against the flow can be reduced, so that this problem can be solved. Further, even in the forced circulation heat pipe that changes the phase of the refrigerant circulation amount, the refrigerant can be efficiently brought into contact with the high-temperature portion of the heat transfer fin, so that improvement in heat transfer efficiency can be expected.

  The effects of the first embodiment and the second embodiment of the present invention will be compared with the results of thermal fluid simulation based on the conventional example. FIG. 8 shows a graph of heat transfer comparison in each example of the present invention. FIG. 9 is a graph of pressure loss comparison in each example of the present invention. As is apparent from FIG. 8, assuming that the heat transfer amount of the conventional example is 100% at each flow rate, both the first embodiment and the second embodiment show only a decrease of about 2%. Further, as shown in FIG. 9, in the first embodiment, a pressure loss reduction effect of 7% to 10% is seen through each flow rate as compared with the conventional example. In the second embodiment, a pressure loss reduction effect of 10% or more is observed at each flow rate. In the third embodiment, the same effect is expected to reduce the pressure loss due to the refrigerant or the refrigerant in which a part of the refrigerant has undergone phase change and mixed phase until the phase change. Moreover, since a refrigerant | coolant can contact a refrigerant | coolant efficiently to the high temperature part of a heat-transfer fin, the improvement of heat-transfer efficiency can be anticipated.

  The present invention reduces the pressure loss without significantly impairing the heat transfer performance, so that the cooling efficiency can be increased as a whole without using a powerful pump. Therefore, the heat generating electronic components are cooled by circulating the refrigerant. It is suitably used as a cooling device for electronic components.

1 is a configuration diagram of an electronic device including a cooling device according to Embodiment 1 of the present invention. Sectional drawing of the heat exchange means of the cooling device in Embodiment 1 of this invention Overview perspective sectional view of base plate and heat transfer fin of cooling device in embodiment 1 of the present invention Temperature distribution diagram of base plate and heat transfer fin of cooling device in Embodiment 1 of the present invention obtained by thermal fluid simulation Temperature distribution perspective view by thermal fluid simulation with conventional heat transfer fins Overview perspective sectional view of base plate and heat transfer fin of cooling device in embodiment 2 of the present invention Overview perspective view of base plate and heat transfer fin of cooling device in embodiment 3 of the present invention Graph of heat transfer comparison in each embodiment of the present invention Graph of pressure loss comparison in each example in the present invention Configuration diagram of an electronic device equipped with a conventional cooling device Sectional view of heat exchange means of a conventional cooling device Overview perspective view of base plate and heat transfer fin of conventional cooling device Temperature distribution diagram of conventional base plate and heat transfer fin obtained by thermal fluid simulation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing | casing 3 Heat exchange means 4 Exothermic electronic component 5 Board | substrate 7 Radiator 8 Piping 9 Pressure pump 10 Base plate 11,21,31 Heat transfer fin 11a Notch part 12 Inlet 13 Outlet 14 Case

Claims (5)

A closed pipe that circulates the refrigerant is provided with a refrigerant pump, a radiator, and a heat exchanger, the heat exchanger receives heat of an electronic component, transfers heat to the radiator with the refrigerant circulated by the refrigerant pump, and A cooling device that radiates heat from a heat radiating device, wherein the heat exchanger includes a plurality of heat transfer fins in a casing having a refrigerant inlet and outlet, and the heat transfer fins are arranged on a refrigerant inlet side. A cooling device characterized in that the height is lower than the height on the refrigerant outlet side. The refrigerant inlet side portion of the heat transfer fin is formed to have a predetermined length and a continuously increasing height from the inlet side end to the center portion. Cooling system. The cross-sectional area of the heat transfer fin in the flow direction of the refrigerant extends from the heat transfer fin on the side along the flow of the refrigerant to the heat transfer fin in the center, and the heat transfer fin included in the predetermined width of the heat transfer fin is continuous. The cooling device according to claim 1, wherein the cooling device is formed to have a wide sectional area. The cross-sectional area of the heat transfer fin in the flow direction of the refrigerant extends from the heat transfer fin on the side along the flow of the refrigerant to the heat transfer fin in the center, and the heat transfer fin included in the predetermined width of the heat transfer fin is continuous. In addition, each heat transfer fin is formed so as to continuously increase in height from the refrigerant inlet side end to the center of the heat transfer fin. The cooling device according to claim 1. The cooling apparatus according to any one of claims 1 to 4, wherein the heat exchanger performs heat exchange by changing a phase of a refrigerant.

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