JP2012255577A - Loop heat pipe, and electronic apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a loop heat pipe capable of starting smoothly even if a hydraulic fluid remains in a wick incorporated in an evaporator when starting.SOLUTION: A loop heat pipe 10 includes an evaporator 1 heated externally, a condenser 2 for radiating heat to the outside, a steam pipe 3 for feeding the steam 7 of hydraulic fluid from the condenser 2 to the evaporator 1, and a liquid pipe 4 for feeding the hydraulic fluid 6 from the condenser 2 to the evaporator 1 where the evaporator 1 incorporates a wick 5. A heat storage material 11 is disposed at the outer wall of the steam pipe 3 of the evaporator 1, and by setting the temperature rising rate of the liquid pipe side 4 of the evaporator 1 of an initial operation higher than that of the steam pipe 3 side, the hydraulic fluid of a liquid phase remaining in the evaporator 1 is discharged from the evaporator 1 within a short period of a time to improve a startup property. The evaporator 1 becomes the cooling device 30 of a heating element when it is attached to the heating element 21 on a circuit board 20 incorporated into the electronic apparatus.

Description

  The present application relates to a loop heat pipe and an electronic apparatus including the heat pipe. In the embodiments described below, a fluid conveyance device (heat pipe) that conveys fluid and an electronic device including the heat pipe will be described as examples.

  Conventionally, a heat pipe that transports heat by the latent heat of a fluid (working fluid) is known. Among these, in the loop heat pipe, an evaporator that is heated from the outside to cause evaporation of the working liquid and a condenser that dissipates heat to the outside and condenses the steam form a loop by the steam pipe and the liquid pipe. Are connected together. The configuration of such a loop heat pipe (also called a circulation heat pipe) is disclosed in FIG.

  In the loop heat pipe, a working fluid vapor generated in the evaporator flows into the condenser through a steam pipe, and a working fluid that has become liquid in the condenser flows into the evaporator through a liquid pipe. The working fluid and the working fluid vapor circulate between the evaporator and the condenser by using the wick capillary pressure in the fluid pipe or the evaporator as a pumping force. The wick is made of, for example, a porous material made of ceramic, nickel, copper, copper oxide or the like, or a porous material made of a polymer material such as polyethylene resin.

  The wick provided in the liquid pipe is attached to the inner peripheral surface of the liquid pipe. On the other hand, the wick provided in the condenser has a cylindrical shape, with the opening located on the liquid pipe side and the bottom located on the steam pipe side. On the outer peripheral surface of the cylindrical wick provided in the condenser, a plurality of grooves, which are grooves having a predetermined depth from the bottom side, are provided in parallel to the axis of the wick.

  Such a loop heat pipe can smoothly flow the working fluid because the liquid and the vapor do not become counterflows unlike the straight pipe heat pipe. Therefore, the loop heat pipe is used for heat transport or cooling in the top heat mode, in which heat transport is difficult with a straight pipe heat pipe. In top heat mode, the evaporator, which is heated from the outside and causes evaporation of the hydraulic fluid, is placed higher than the condenser where the hydraulic fluid vapor releases heat to condense and transports heat from top to bottom. It is a form of heat transport.

  In the loop heat pipe, the liquid phase and the gas phase hydraulic fluid coexist in the groove of the evaporator, and the startability of the loop heat pipe after the heat is applied to the evaporator due to the distribution of the hydraulic fluid in the groove. Is different. In particular, when there is a liquid-phase working fluid in the groove, heating is necessary to evaporate the working fluid in the groove, so the loop heat pipe starts up after the evaporator is heated. Takes time. During this time, since the effective use area of the wick is small, there is a problem that the heat pump does not operate up to an operating temperature higher than the designed operating temperature due to a decrease in wick pump power and an increase in thermal resistance due to a decrease in groove utilization rate. This problem is also reported in Non-Patent Document 1.

Japanese Patent No. 4459783 (FIG. 1)

Jentung Ku; 1998 Operating Characteristics of Loop Heat Pipes. Society of Automotive Engineers, Inc.

  Thus, when the liquid phase hydraulic fluid is present in the groove of the evaporator, the start of the loop heat pipe is delayed, and when the loop heat pipe is used as a semiconductor cooling device, the temperature of the semiconductor becomes the specified temperature. This has caused a problem that causes damage to the semiconductor. However, although Non-Patent Document 1 describes this phenomenon, there is no description of a solution for avoiding this phenomenon.

  The present application provides a loop heat pipe capable of quickly starting a loop heat pipe and a cooling device using the heat pipe at the time of starting the loop heat pipe in which a large amount of hydraulic fluid remains in the wick groove. It is aimed.

  In order to achieve the above object, a loop heat pipe of the present application includes an evaporator including a wick, a condenser, and a liquid pipe and a vapor pipe connecting the evaporator and the condenser. It is characterized in that a temperature difference generating means is provided so that the second part on the liquid pipe side is hotter than the first part on the steam pipe side during heat input from the cold.

  In addition, an electronic device of the present application for achieving the above object includes an electronic component, an evaporator in thermal contact with the electronic component, a wick built in, a condenser, and a liquid that connects the evaporator and the condenser. In the evaporator, the second part on the liquid pipe side is higher in temperature than the first part on the steam pipe side when heat is input from the electronic component from the cold. It is characterized by having a loop heat pipe provided with a temperature difference generating means.

  According to the heat pipe of the present application, even if there is a lot of residual hydraulic fluid in the groove of the wick, the temperature rise rate on the liquid pipe side of the evaporator becomes faster than the temperature rise speed on the steam pipe side when starting the heat pipe, The residual hydraulic fluid is discharged in a short time, and the startability of the heat pipe is improved. In addition, according to the electronic device of the present application, when the electronic device is started from cold, the temperature of the heating element on the circuit board is excessively increased by the loop heat pipe provided with the temperature difference generating means in the evaporator. It is possible to start without making it.

(A) is a figure which shows the structure of the conventional loop heat pipe, (b) is the perspective view which looked at the wick built in the evaporator of (a) from the inlet side of the hydraulic fluid, (c) is the figure of (a) It is the perspective view which looked at the wick built in the evaporator from the exit side of hydraulic fluid. (A) is a diagram showing a state in which the clogging of the wick groove in the evaporator shown in FIG. 1 (a) is small when the loop heat pipe is started, and there is a little liquid-phase working fluid in the groove; (B) is a characteristic diagram showing a temperature change of the semiconductor integrated circuit with respect to time when heat is applied to the evaporator of the loop heat pipe in the state shown in (a). (A) is the figure which shows the state where the clogging of the groove | channel of the wick in the evaporator shown to Fig.1 (a) is large at the time of the start of a loop heat pipe, and a large amount of liquid-phase hydraulic fluid exists in a groove (B) is a characteristic view showing a temperature change of the semiconductor integrated circuit with respect to time when heat is applied to the evaporator of the loop heat pipe in the state shown in (a). It is an assembly perspective view which shows one Example of the process of attaching the thermal storage material of this application to the evaporator of a loop heat pipe. It is an assembly perspective view which shows the process of attaching the evaporator of the loop heat pipe to which the heat storage material of this application shown to Fig.4 (a) was attached to the semiconductor integrated circuit mounted in the circuit board, and comprising a cooling device. . (A) is a perspective view showing a configuration of an embodiment of a cooling device in which a heat storage material of the present application is attached to an evaporator of a loop heat pipe in which one wick is incorporated, and (b) is a diagram in which two wicks are incorporated. It is a perspective view which shows the structure of the Example which attached the thermal storage material of this application to the evaporator of the made loop heat pipe. (A) is sectional drawing in the AA line of FIG. 6 (a) of the cooling device provided with the evaporator of this application to which the latent heat storage material of melting | fusing point 40 degreeC was attached, (b) is (a). The figure which shows the thermal gradient of the evaporator immediately after a semiconductor integrated circuit starts operation | movement in a state, (c) is (b) with respect to time when a semiconductor integrated circuit starts operation | movement in the state shown to (a). It is a characteristic view which shows the temperature change of a semiconductor integrated circuit. It is a figure which shows the relationship between the thickness of the latent-heat storage material shown to Fig.6 (a), the usage-amount, and delay time. (A) is sectional drawing in the AA of FIG. 6 (a) of the cooling device provided with the evaporator of this application to which the latent heat storage material of melting | fusing point 50 degreeC was attached, (b) is (a). The figure which shows the thermal gradient of the evaporator immediately after a semiconductor integrated circuit starts operation | movement in a state, (c) is (b) with respect to time when a semiconductor integrated circuit starts operation | movement in the state shown to (a). It is a characteristic view which shows the temperature change of a semiconductor integrated circuit. (A) is sectional drawing of the principal part of the cooling device provided with the evaporator of the state which removed the latent heat storage material, (b) of the evaporator immediately after a semiconductor integrated circuit started operation | movement in the state of (a) FIG. 5C is a characteristic diagram showing a temperature change of the semiconductor integrated circuit with respect to time when the semiconductor integrated circuit starts operating in the state shown in FIG.

  Hereinafter, embodiments of the present application will be described in detail based on specific examples with reference to the accompanying drawings. Prior to describing the embodiments of the present application, the configuration and start-up of a conventional loop heat pipe will be described. The problem of time will be described with reference to FIGS.

  FIG. 1A shows a configuration of a conventional loop heat pipe 10. The loop heat pipe 10 includes an evaporator 1, a condenser 2, a steam pipe 3 for sending the working liquid vapor 7 from the evaporator 1 to the condenser 2, and a liquid pipe for sending the working liquid 6 from the condenser 2 to the evaporator 1. There are four. The evaporator 1 is heated from the outside to convert the working fluid into vapor, and the condenser 2 condenses the vapor by dissipating heat to the outside to form a liquid-phase working fluid. In the evaporator 1, a wick 5 is provided that generates a capillary pressure that causes the working fluid 6 condensed in the condenser 2 to flow back to the evaporator 1. If the evaporator 1 is attached to the heating element, the heating element can be cooled.

  The wick 5 has a cylindrical shape as shown in FIGS. 1B and 1C, and the liquid pipe 4 side is open to be provided with a hollow portion 8. Further, on the outer peripheral surface of the wick 5, grooves 9 that are a plurality of grooves are provided in the axial direction of the wick 5 from the evaporation tube 3 side toward the liquid tube 4 side. The wick 5 is a porous body made of ceramic, metal, resin or the like. The inside of the loop heat pipe 10 is completely evacuated, and then a liquid such as water, alcohol, or fluorinated hydrocarbon compound is sealed as a working fluid (working fluid). The working fluid is vaporized in the wick 5 of the evaporator 1 to which heat is applied, the liquid-phase working fluid 6 becomes steam 7 and flows through the steam pipe 3, and in the condenser 2, the steam 7 becomes liquid-phase working fluid 6 and evaporates. Reflux to vessel 1. The hydraulic fluid circulates in the loop by the capillary force of the wick 5.

  Fig.2 (a) has shown the part of the evaporator 1 in a cross section before heat is added to the evaporator 1 of a loop heat pipe. In this state, the clogging of the groove 9 of the wick 5 is small, and the liquid-phase working fluid 6a remains in the groove 9 a little. When heat is applied to the evaporator 1 in this state, the amount of the liquid-phase working fluid 6a in the groove 9 is small, so that it evaporates immediately. Therefore, as shown in FIG. 2 (b), at the time of starting heat applied to the evaporator 1 of the loop heat pipe, the wick 5 performs its original operation after the liquid-phase working fluid 6a in the groove 9 evaporates. . As a result, the temperature of the semiconductor integrated circuit to which the evaporator 1 is attached only rises slightly from the target temperature at first, and thereafter changes in a state close to the target temperature.

  FIG. 3A shows a section of the evaporator 1 in a cross section before heat is applied to the evaporator 1 of the loop heat pipe. In this state, the clogging of the groove 9 of the wick 5 is large, and a large amount of liquid-phase working fluid 6a remains in the groove 9. When heat is applied to the evaporator 1 in this state, since the residual amount of the liquid-phase working fluid 6a in the groove 9 is large, the liquid-phase working fluid 6a is evaporated and the liquid-phase working fluid 6a in the groove 9 is evaporated. It takes time to be discharged. Then, as shown in FIG. 2 (c), at the time of starting the heat to be applied to the evaporator 1 of the loop heat pipe, the wick 5 is originally kept until the liquid-phase working fluid 6a in the groove 9 is completely evaporated. Can not be performed. As a result, the temperature of the semiconductor integrated circuit to which the evaporator 1 is attached first exceeds the specification temperature. After the liquid-phase working fluid 6a in the groove 9 has completely evaporated, the state changes to a state close to the target temperature.

  As described above, when the loop heat pipe is started in a state where the liquid phase hydraulic fluid 6a exists in the groove 9 of the evaporator 1, it takes time until the loop heat pipe operates normally. For this reason, when the loop heat pipe is used as a cooling device for a semiconductor mounted on an electronic device, the temperature of the semiconductor integrated circuit to which the evaporator 1 is attached exceeds the specified temperature of the semiconductor, and the semiconductor is damaged. There was a problem to cause.

  The present application starts the loop heat pipe quickly without incurring excessive temperature rise (overheating) of the evaporator when the loop heat pipe is started in a state where a lot of liquid-phase hydraulic fluid remains in the wick groove. It can be made to. Hereinafter, a loop heat pipe and an electronic device using the loop heat pipe will be described.

  In order to start the loop heat pipe so as to minimize overheating, it is necessary to quickly remove the working fluid remaining in the groove at the time of heat input when heat is applied to the evaporator. Therefore, in order to start the loop heat pipe so as to minimize overheating, the present inventors have only to make the temperature rise rate of the vapor side and the liquid side of the evaporator different from each other at the time of heat input. I found. This is because, when the heating rate of the first part on the vapor pipe side of the evaporator and the second part on the liquid pipe side are different at the time of heat input, steam is preferentially generated from the side where the temperature has risen first. This is because, as a result, the hydraulic fluid remaining in the groove can be quickly pushed out by the generated steam pressure.

  At the start of the loop heat pipe, in order to make a difference in the temperature rise rate of the evaporator, materials with different heat capacities are joined to make an evaporator, a cooler is applied to half of the evaporator, and half of the evaporator is heated. It is possible to use a method such as placing a heater or installing a heat storage material on the vapor side of the evaporator. Considering that the temperature rise only needs to be different only in the process leading to the superheated state at the initial stage of heat input, the present inventors have devised a device that uses a heat storage material to make a difference in the temperature rise rate of the evaporator. In particular, a heat storage material using latent heat can cope with a large amount of heat even with a small amount, so an apparatus using latent heat has been devised.

  Examples of the latent heat storage material include calcium chloride hydrate, sodium sulfate hydrate, sodium acetate hydrate, sodium thiosulfate hydrate, paraffin, and the like. Paraffin-based materials were used. This is because the melting temperature of paraffinic materials can be set in a wide range by controlling the molecular weight. The latent heat storage material used the sheet | seat which sealed the paraffin to the aluminum laminate film, and aimed at the improvement of heat-transfer efficiency and cycling characteristics. As such a latent heat storage material, MHS series (registered trademark) manufactured by Mitsubishi Electric Cable can be used. This is because this material is very easy to adapt because it can be handled as a solid in appearance as a bulk even if a phase change occurs inside as a latent heat storage material. There are many other types of materials other than those listed here, and each can be adapted.

  From the above, in this application, a latent heat storage material (hereinafter simply referred to as a heat storage material) in which paraffin is sealed in an aluminum laminate film is attached to the evaporator of the loop heat pipe, and heat is supplied to the evaporator when the loop heat pipe is started. A gradient was added. As a result, even when a large amount of hydraulic fluid remained in the groove of the wick of the loop heat pipe, the hydraulic fluid was quickly discharged from the groove. The attachment of the heat storage material of the present application to the evaporator will be described below. In addition, the same code | symbol is attached | subjected and demonstrated to the same structural member as before.

  FIG. 4 shows a process of attaching the heat storage material 11 of one embodiment of the present application to the steam pipe 3 side of the evaporator 1 of the loop heat pipe. In this embodiment, the evaporator 1, the steam pipe 3 and the liquid pipe 4 have a rectangular cross section, but the evaporator 1, the steam pipe 3 and the liquid pipe 4 may have a circular cross section. In the present application, the heat storage material 11 covering the outer wall 1A is attached to the outer wall 1A on the steam pipe 3 side of the evaporator 1. In this embodiment, the heat storage material 11 is divided into a left heat storage material 11A and a right heat storage material 11B in advance in order to cover the entire circumference of the evaporator 1 on the steam pipe 3 side. And the recessed part 11C is formed inside 11A of left side heat storage materials, and the right side heat storage material 11B according to the shape of the evaporator 1. FIG. The method of dividing the heat storage material 11 is not limited to right and left division. The length L of the heat storage material 11 attached to the evaporator 1 and the thickness T of the heat storage material 11 will be described later.

  In addition, when using the sheet | seat which sealed the paraffin in the aluminum laminate film as the thermal storage material 11, the left thermal storage material 11A and the right thermal storage material 11B of a shape as shown in FIG. 4 are formed as a metal housing, and a sheet | seat is formed inside Can be packed or filled with paraffin. Alternatively, the sheet-shaped heat storage material 11 may be directly wound around the outer wall 1A of the evaporator 1 on the steam pipe 3 side.

  When the left heat storage material 11A and the right heat storage material 11B shown in FIG. 4 are attached to the outer wall 1A on the steam pipe 3 side of the evaporator 1, the result is as shown in FIG. The evaporator 1 to which the heat storage material 11 is attached is attached via a heat spreader 22 on a semiconductor integrated circuit 21 which is a heat generating member mounted on a circuit board 20 of an electronic device, and a semiconductor cooling device 30 is configured. Is done. Although the illustration of the method of attaching the evaporator 1 to the circuit board 20 is omitted, a flange portion or the like may be provided on the evaporator 1 and attached using screws or the like.

  In this embodiment, since the semiconductor integrated circuit 21 mounted on the circuit board 20 is cooled by the evaporator 1 as a heating element, the bottom surface of the evaporator 1 is formed flat, and the sheet-like heat spreader 22 is interposed therebetween. Thus, the evaporator 1 is attached to the semiconductor integrated circuit 21. On the other hand, when the heating element does not have a flat shape, the bottom surface of the evaporator 1 may be formed according to the shape of the heating element, or the heat spreader 22 may be configured according to the shape of the heating element.

  The semiconductor cooling device 30 incorporated in the electronic device shown in FIG. 5 operates to take heat from the semiconductor integrated circuit 21 and cool it when the circuit board 20 of the electronic device operates and the semiconductor integrated circuit 21 generates heat. I do. The operation of the evaporator 1 in the semiconductor cooling device 30 will be described below.

  FIG. 6A shows a configuration of an embodiment of the semiconductor cooling device 30 in which the heat storage material 11 of the present application is attached to the evaporator 1 of the loop heat pipe 10 in which one wick 5 is incorporated. is there. The evaporator 1 incorporating the cylindrical wick 5 has a rectangular cross section, and the flat bottom surface 1B of the evaporator 1 is mounted on the semiconductor integrated circuit 21 mounted on the circuit board 20 via the heat spreader 22. Thus, the semiconductor cooling device 30 is configured. Moreover, the cross section of the vapor | steam pipe | tube 3 connected to the evaporator 1 and the liquid pipe | tube 4 is circular in this Example.

  FIG. 6B shows a configuration of an embodiment of the semiconductor cooling device 30 in which the heat storage material 11 of the present application is attached to the evaporator 1 of the loop heat pipe 10 in which two wicks 5 are incorporated. The circuit board 20, the semiconductor integrated device 21, and the heat spreader 22 are not shown. The evaporator 1 incorporating two cylindrical wicks 5 in parallel has a rectangular cross section. The evaporator 1 of this embodiment is used when the semiconductor integrated circuit 21 mounted on the circuit board 20 is large. Also in this embodiment, the cross sections of the steam pipe 3 and the liquid pipe 4 connected to the evaporator 1 are circular. If the semiconductor integrated circuit 21 mounted on the circuit board 20 is larger and it is necessary to cool a wider area, the number of wicks 5 arranged in parallel may be increased.

  Fig.7 (a) has shown the cooling device 30 for semiconductors provided with the evaporator 1 of this application with which the thermal storage material 11 of melting | fusing point 40 degreeC was attached, In the AA line of Fig.6 (a) The cross section of the cooling device 30 for semiconductors is shown. The attachment length L of the heat storage material 11 to the evaporator 1 may be such that the heat storage material 11 covers half the length M of the groove 9 provided in the wick 5. The semiconductor integrated circuit 21 of this embodiment is a 30 mm square heating element used at an operating temperature of 60 ° C. and a specified temperature of 70 ° C. Further, the evaporator 1 of the loop heat pipe 10 is a 40 mm square that is slightly larger than the semiconductor integrated circuit 21 and has a thickness of 10 mm. The total amount of paraffin used was 7.5 g. However, FIG. 7A does not accurately represent this dimension.

  FIG. 7B shows the thermal gradient of the evaporator 1 immediately after the operation of the semiconductor integrated circuit 21 in the state of FIG. That is, FIG. 7B shows the temperature gradient when the end of the evaporator 1 on the liquid tube 4 side is “0” and the other end is “L”. When the semiconductor integrated circuit 21 starts operating from the cold state and generates heat, the temperature on the liquid tube 4 side of the evaporator 1 rises, but the temperature on the evaporator tube 3 side of the evaporator 1 is absorbed by the heat storage material 11. It will not rise. As a result, immediately after the operation of the semiconductor integrated circuit 21 is started, the temperature on the liquid tube 4 side of the evaporator 1 is high, and the temperature on the vapor tube 3 side is low. When the electronic device is turned on and the semiconductor integrated circuit 21 starts operating from a cold state and a predetermined time elapses, the heat storage amount of the heat storage material 11 is saturated, and thereafter the heat does not absorb heat. The temperature on the 3 side rises and becomes the same as the temperature on the liquid tube 4 side.

  FIG. 7C shows a change in temperature of the semiconductor integrated circuit 21 with respect to time after the semiconductor integrated circuit 21 mounted on the electronic device starts operating in the state of FIG. Thus, if the evaporator 1 of this application which attached the heat storage material 11 is used, the temperature of the semiconductor integrated circuit 21 which is an electronic component which heats in an electronic device will not exceed specification temperature.

  FIG. 8 is a diagram showing the relationship between the thickness T, the amount used, and the delay time of the heat storage material 11 shown in FIG. The latent heat of melting of a paraffinic system having a melting point of 40 ° C. is equivalent to 200 J / kg, the heat generation amount of the semiconductor integrated circuit 21 is 100 W, and the size of the case of the evaporator 1 is 40 mm square. And when the heat storage material 11 is attached to the steam pipe 3 side of the case of the evaporator 1, the area where the heat storage material 11 covers the case of the evaporator 1 is 24 square centimeters. Moreover, the specific gravity of the heat storage material 11 is calculated as 1 g / cc. From the calculation result shown in FIG. 8, when the difference in temperature rise rate is 5 seconds or more between the liquid pipe side and the steam pipe side of the case of the evaporator 1 as the delay time, the thickness T of the heat storage material 11 1 mm or more is suitable. However, if the thickness T of the heat storage material 11 is increased, it becomes difficult to install the heat storage material 11 in the case of the evaporator 1, so the thickness T of the heat storage material 11 is considered to be within 4 mm.

  FIG. 9A shows a cooling device 30 for a semiconductor provided with the evaporator 1 of the present application to which a heat storage material 11 having a melting point of 50 ° C. is attached. FIG. In this state, the thermal gradient of the evaporator immediately after the operation of the semiconductor integrated circuit 30 of the electronic device is shown. The fact that a sheet in which paraffin is sealed with an aluminum laminate film is used as the heat storage material 11 is the same as the heat storage material 11 in FIG. 8A, and the total amount of paraffin is 7.5 g. FIG. 9C shows the temperature change of the semiconductor integrated circuit 30 with respect to time when the semiconductor integrated circuit 30 starts operating in the state shown in FIG. 9A.

  Thus, even if the melting point of the heat storage material 11 is changed to 50 ° C., the overheating state in the initial operation of the semiconductor cooling device 30 mounted on the electronic device using the loop heat pipe 10 is effectively suppressed. However, the target temperature at the initial stage of operation is higher than when the melting point is 40 ° C. Therefore, the melting point of the heat storage material 11 may be appropriately selected according to the size of the evaporator 1 and the like.

  FIG. 10A shows a main part of a cooling device 30 for a semiconductor of an electronic apparatus provided with the evaporator 1 with the heat storage material 11 removed, and FIG. 10B shows the main part of FIG. In this state, the thermal gradient of the semiconductor evaporator 21 immediately after the operation of the semiconductor integrated circuit 21 is shown. FIG. 10C is a characteristic diagram showing a temperature change of the semiconductor integrated circuit 21 with respect to time when the semiconductor integrated circuit 21 starts operating in the state shown in FIG. As described above, in a state where the heat storage material 11 is not attached to the evaporator 1, the overheat state cannot be suppressed in the initial operation of the semiconductor integrated circuit 21, and the semiconductor integrated circuit 21 causes an overshoot exceeding the specified temperature. From the above, the semiconductor cooling device 30 using the loop heat pipe of the present application that uses the heat storage material 11 and has a difference in the temperature rise rate of the evaporator 1 in the initial operation of the semiconductor integrated circuit 21 is an excellent start-up. It can be seen that it shows performance.

  As mentioned above, although this application was explained in full detail about the preferable embodiment in particular, this application is not limited to specific embodiment, In the range of the summary of this application described in the claim, various Can be modified and changed. In other words, in order to make a difference in the temperature rise rate of the evaporator, in addition to the structure in which the heat storage material is installed on the vapor side of the evaporator, the structure in which the evaporator is made by joining materials with different heat capacities, half of the evaporator It is possible to adopt a configuration in which a cooler is applied to the heater, and a heater is applied to half of the evaporator. Here, for easy understanding of the present application, specific forms of the present application are appended below.

(Appendix 1) an evaporator with a built-in wick;
A condenser,
A liquid pipe and a steam pipe connecting the evaporator and the condenser;
The evaporator is provided with a temperature difference generating means that causes the second part on the liquid pipe side to be higher in temperature than the first part on the steam pipe side when heat is input from the cold. Loop heat pipe.
(Supplementary note 2) The loop heat pipe according to supplementary note 1, wherein the temperature difference generating means is a heat storage material covering an outer periphery of the evaporator corresponding to the second part.
(Appendix 3) The temperature difference generating means is obtained by joining the first part and the second part of the evaporator with materials having different heat capacities to form an evaporator. Loop heat pipe.
(Additional remark 4) The said temperature difference generation means is comprised by assigning a cooler to the 1st part of the said evaporator, The loop heat pipe of Additional remark 1 characterized by the above-mentioned.
(Additional remark 5) The said temperature difference generation means is comprised by assigning a heater to the 2nd part of the said evaporator, The loop heat pipe of Additional remark 1 characterized by the above-mentioned.

(Additional remark 6) The said temperature difference production | generation means is the temperature of the 2nd site | part by the side of the said liquid pipe at the time of the temperature rise rate of the 1st site | part by the side of the said steam pipe at the time of the heat input to the said evaporator from cold The loop heat pipe according to appendix 1, wherein the loop heat pipe is configured to be slower than the rising speed.
(Appendix 7) The wick is cylindrical and the liquid pipe side is open, and a plurality of grooves are provided on the outer peripheral surface of the wick in the axial direction of the wick from the evaporation pipe side to the liquid pipe side. And
The second part on the liquid pipe side is a part from the end part on the evaporator pipe side of the evaporator to a position of an intermediate part of the groove. Loop heat pipe.
(Additional remark 8) The loop heat pipe of Additional remark 7 characterized by using the sheet | seat which sealed the paraffin with the aluminum laminate film for the said heat storage material.
(Additional remark 9) The thickness of the said thermal storage material is 1-4 mm, The loop heat pipe of Additional remark 8 characterized by the above-mentioned.
(Supplementary Note 10) Electronic components,
An evaporator in thermal contact with the electronic component and containing a wick;
A condenser,
A liquid pipe and a steam pipe connecting the evaporator and the condenser;
In the evaporator, a temperature difference generating means that causes the second part on the liquid pipe side to be higher in temperature than the first part on the steam pipe side when heat is input from the electronic component from a cold state. An electronic device comprising a loop heat pipe to be provided.

DESCRIPTION OF SYMBOLS 1 Evaporator 1A Outer wall 1B Bottom part 2 Condenser 3 Steam pipe 4 Liquid pipe 5 Wick 6 Hydraulic fluid 7 Hydraulic fluid vapor 8 Hollow part 9 Groove (groove)
DESCRIPTION OF SYMBOLS 10 Heat pipe 11, 11A, 11B Thermal storage material 11C Recessed part 20 Circuit board 21 Integrated circuit 30 Semiconductor cooling device

Claims (3)

An evaporator with a built-in wick,
A condenser,
A liquid pipe and a steam pipe connecting the evaporator and the condenser;
The evaporator is provided with a temperature difference generating means that causes the second part on the liquid pipe side to be higher in temperature than the first part on the steam pipe side when heat is input from the cold. Loop heat pipe.   The loop heat pipe according to claim 1, wherein the temperature difference generating means is a heat storage material that covers an outer periphery of the evaporator corresponding to the second part. Electronic components,
An evaporator in thermal contact with the electronic component and containing a wick;
A condenser,
A liquid pipe and a steam pipe connecting the evaporator and the condenser;
In the evaporator, a temperature difference generating means that causes the second part on the liquid pipe side to be higher in temperature than the first part on the steam pipe side when heat is input from the electronic component from a cold state. An electronic device comprising a loop heat pipe to be provided.

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