JP5344847B2 - Cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling apparatus for suppressing dropping of circulation speed of a working fluid even under a condition wherein a heat value of a heating element is small when carrying out cooling of the heating element by using a loop heat pipe. <P>SOLUTION: The cooling apparatus includes an evaporator evaporating the working fluid of a liquid phase during passing of a wick composed of a porous material by heat received from the heating element, a condenser discharging heat of the working fluid of a gaseous phase and condensing the working fluid, a plurality of loop heat pipes having a steam pipe moving the working fluid of the gaseous phase evaporated by the evaporator from the evaporator to the condenser, and a liquid pipe moving the working fluid of the liquid phase condensed by the condenser from the condenser to the evaporator, and comprised by thermally joining respective evaporators by a common heating element, a heat value detecting means for detecting the heat value of the heating element, and a switching control part carrying out switching control between operation and stopping of the plurality of loop heat pipes in response to the heat value detected by the heat value detecting means. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present case relates to a cooling device including a loop heat pipe.

  In today's society, a wide variety of electronic devices have been developed with the progress of industrial technology, and there are many electronic devices having a complicated configuration. Particularly in recent years, with the progress of the information society, technologies related to electronic devices that perform information processing, such as computers, are rapidly developing, and high-performance electronic devices having complicated configurations are being developed one after another.

  Electronic devices generally have a complicated electronic circuit inside the electronic device, and when operating as an electronic device, such an electronic circuit often generates heat. For example, in a computer, a CPU that plays a central role in computer operation control generates heat as the computer operates. When an electronic circuit generates heat, the heat may cause problems in the electronic circuit and other electronic components around it, so there is a heat transport mechanism for releasing the generated heat from the electronic circuit to other locations. It is often necessary.

  Conventionally, a heat transport device called a loop heat pipe is known as a heat transport mechanism. A loop heat pipe has a configuration in which a working fluid is sealed inside a container such as a pipe, and heat is transported by moving the working fluid that has absorbed heat inside the heat pipe (for example, Patent Documents). 1). Here, the configuration and operating principle of the loop heat pipe will be described.

  FIG. 1 is a schematic configuration diagram showing the configuration and operating principle of a loop heat pipe.

  The loop heat pipe shown in FIG. 1 includes an evaporator 101 in which the liquid-phase working fluid 100 absorbs heat from a heating element (not shown) and vaporizes, and the gas-phase working fluid 100 releases heat and liquefies. And a condenser 105. In this loop heat pipe, the working fluid 100 vaporized in the evaporator 101 moves through the vapor pipe 104 in the upward arrow direction in the figure and is liquefied in the condenser 105, and the liquefied working fluid 100 is in the liquid pipe 102. It moves in the downward arrow direction through the figure and returns to the evaporator 101. Heat is transported by such movement of the working fluid 100. Here, a wick 1003 made of a porous material is provided inside the evaporator 101, and the liquid-phase working fluid 100 that has returned to the evaporator 101 penetrates into the wick 103 by capillary force. The vaporized working fluid 100 is vaporized by receiving heat from the surroundings, and travels to the condenser 105 via the vapor pipe 104.

  FIG. 2 is a diagram schematically showing how the working fluid 100 changes through the wick 103 and changes from the liquid phase to the gas phase.

Actually, the passages (cavities) in the wick 3 ′ through which the liquid-phase working fluid 100 permeates are winding and complicated, but in this figure, the plurality of passages in the wick 3 ′ are left and right. It is schematically represented as a cylindrical passage that extends parallel to the direction. In this figure, the liquid-phase working fluid 100 proceeds to the right in the wick 103 by capillary force, and is vaporized by receiving heat from the surroundings. Here, the boundary surface between the side in which the working fluid 100 is in a liquid phase (liquid side) and the side in which the working fluid 100 is in a gas phase (steam side), as shown in FIG. The shape is convex toward the liquid side, and the capillary force ΔPc is expressed by the following equation.
ΔPc = (2 × ρ × cos θc) / rc (1)
In the above (1), “ρ” is the surface tension of the working fluid 100, and “θc” is the contact angle between the wall surface of the cylindrical passage and the boundary surface (see FIG. 2), “rc”. Is the radius of the cylindrical passage.

  Next, a conventional cooling device that cools the CPU of a computer using the loop heat pipe whose operation principle is shown in FIG. 1 will be described.

  FIG. 3 is a diagram showing a conventional cooling device 200 ′ provided in the computer 1000 ′.

  A conventional cooling device 200 ′ shown in FIG. 3 is a cooling device 200 ′ that cools the CPU 20 by absorbing heat from the CPU 20 of the computer 1000 ′ and releasing the heat to the outside of the computer 1000 ′. The apparatus 200 ′ uses a loop heat pipe whose operating principle is shown in FIG. Specifically, in the cooling device 200 ′, the liquid phase working fluid 100 (not shown in FIG. 3) absorbs heat from the CPU 20 and vaporizes, and the gas phase working fluid 100 is heated. The working fluid 100 vaporized in the evaporator 1 ′ moves upward in the figure through the vapor pipe 4 ′ and is liquefied in the condenser 5 ′. To do. Here, the cooling device 200 ′ is provided with a fan 6 ′ that blows air toward the condenser 5 ′. The working fluid 100 that receives air from the fan 6 ′ and passes through the condenser 5 ′ is heated. To liquefy. Note that the wind that has been heated to include this heat is released to the outside of the computer 1000 '. The working fluid 100 liquefied by the condenser 5 ′ moves through the liquid pipe 2 ′ in the downward arrow direction in the figure, and returns to the evaporator 1 ′ through the reservoir tank 7 ′. Here, a wick (not shown in FIG. 3) made of a porous material is provided inside the evaporator 1 ′, and the liquid-phase working fluid 100 returned to the evaporator 1 ′ is In the same manner as described with reference to FIG. 1, the capillary force by the wick penetrates the wick and changes from the liquid phase to the gas phase.

In the conventional cooling device of FIG. 3, the heat transport by the working fluid 100 as described above is repeated, and the CPU 20 is thereby cooled.
US Pat. No. 4,765,396

  In general, in a cooling device using a loop heat pipe, the capillary force due to the wick in the evaporator decreases as the amount of heat supplied from the heating element to the evaporator decreases, and the circulating speed of the working fluid tends to decrease.

  FIG. 4 is a diagram showing the state of the boundary surface between the liquid side and the vapor side according to the heat generation amount of the heating element.

  Here, part (a) of FIG. 4 shows the state of the boundary surface between the liquid side and the vapor side of the working fluid in a situation where the heat generation amount of the heating element is large. Further, part (b) of FIG. 4 shows the state of the boundary surface between the liquid side and the vapor side of the working fluid in a situation where the heat generation amount of the heat generating element is small.

  The contact angle θc formed between the wall surface of the cylindrical passage and the boundary surface is supplied from the heating element to the evaporator in the situation of part (b) in FIG. 4 where the amount of heat supplied from the heating element to the evaporator is small. Compared with the situation of part (a) of FIG. 4 where the amount of heat is large, the capillary force ΔPc is small. In this way, when the capillary force ΔPc is small, the circulation speed of the working fluid is reduced, so that even if the amount of heat generation is small, the temperature around the heating element gradually rises, and there is a risk of causing problems in the electronic components around the heating element. is there. In particular, in a situation where the circulation speed of the working fluid has become completely zero, the working fluid supplied to the evaporator is insufficient, so-called dryout occurs, and the temperature rise around the heating element becomes serious. .

  In view of the above circumstances, a cooling device is provided that can suppress a decrease in the circulation speed of a working fluid even when a heating element is cooled using a loop heat pipe, even under a situation where the heating element generates a small amount of heat.

The basic form of the cooling device that achieves the above object is as follows:
An evaporator having a wick composed of a porous material, the liquid phase working fluid passing through the wick being evaporated by heat received from a heating element;
A condenser that releases heat of the gas-phase working fluid to condense the working fluid;
A vapor pipe that connects the evaporator and the condenser, and moves a vapor-phase working fluid evaporated in the evaporator from the evaporator to the condenser;
The evaporator and the condenser are connected, and a liquid pipe for moving the liquid-phase working fluid condensed in the condenser from the condenser to the evaporator is provided, and each evaporator serves as a common heating element. A plurality of loop heat pipes that are thermally coupled;
A calorific value detection means for detecting the calorific value of the heating element;
According to the heat generation amount detected by the heat generation amount detection means, a switching control unit is provided that performs switching control between operation and stop of the plurality of loop heat pipes.

  According to this basic form, when the heat generation amount of the heating element is small by switching control of the operation and stop of the plurality of loop heat pipes according to the heat generation amount of the heating element, for example, according to the small heat generation amount Only the loop heat pipe can be operated. As a result, according to the basic form of the cooling device, it is possible to suppress a decrease in the circulation speed of the working fluid even under a situation where the heat generation amount of the heating element is small.

Here, the basic form of an electronic device that has such a cooling device and operates well is:
An electronic device provided with a heat generating electronic component that generates heat by operation,
An evaporator having a wick composed of a porous material, and evaporating a liquid-phase working fluid passing through the wick by heat received from the heat-generating electronic component;
A condenser that releases heat of the gas-phase working fluid to condense the working fluid;
A vapor pipe that connects the evaporator and the condenser, and moves a vapor-phase working fluid evaporated in the evaporator from the evaporator to the condenser;
The evaporator and the condenser are connected, and a liquid pipe for moving the liquid-phase working fluid condensed in the condenser from the condenser to the evaporator is provided, and each evaporator serves as a common heating element. A plurality of loop heat pipes that are thermally coupled;
A calorific value detection means for detecting the calorific value of the heat-generating electronic component;
According to the heat generation amount detected by the heat generation amount detection means, a switching control unit is provided that performs switching control between operation and stop of the plurality of loop heat pipes.

  Since the basic form of the electronic device includes the basic form of the cooling device described above, a decrease in the circulation speed of the working fluid can be suppressed even under a situation where the heat generation amount of the heating element is small. As a result, an electronic device that operates well is realized.

  As described above, according to the basic form of the cooling device, when the heating element is cooled using the loop heat pipe, the decrease in the circulation speed of the working fluid is suppressed even under a situation where the heat generation amount of the heating element is small. Can do.

  Hereinafter, specific embodiments of the cooling device and the electronic device described above for the basic mode will be described. The embodiment of the electronic device described here is a computer having a CPU, and the computer includes a cooling device for cooling the CPU that generates heat as the computer operates. This cooling device corresponds to one embodiment of the cooling device described above for the basic mode.

  FIG. 5 is a diagram illustrating a computer 1000 that is an embodiment of an electronic apparatus, and a cooling device 200 provided in the computer 1000.

  The computer 1000 operates under the control of the CPU 20, and the CPU 20 generates heat as the computer operates. The CPU 20 has a square shape with a side length of 50 mm, and the heat generation amount of the CPU 20 is between 10W and 120W.

  The cooling device 200 plays a role of cooling the CPU 20 by absorbing heat from the CPU 20 and releasing the heat to the outside of the computer 1000. In order to transport the heat at this time, the cooling device 200 Is provided with two loop heat pipes whose operation principle is shown in FIG. Here, one of the two loop heat pipes includes a first evaporator 1a, a first condenser 5a, a first liquid pipe 2a, a first steam pipe 4a, and a left loop in the figure. It is a heat pipe, and the other loop heat pipe is a loop heat pipe on the right side of the figure having a second evaporator 1b, a second condenser 5b, a second liquid pipe 2b, and a second steam pipe 4b. is there.

  Heat generated by the CPU 211 is conducted to the first evaporator 1a and the second evaporator 1b, and due to this heat, the liquid-phase working fluid 100 in the first evaporator 1a and the second evaporator 1b (FIG. 1). Reference (not shown in FIG. 5) is vaporized. Specifically, water is employed as the working fluid 100. The outer portions of the first evaporator 1a and the second evaporator 1b are made of a cylindrical copper material of φ15 mm × 50 mm, and the inside of the cylinder is made of a porous stainless sintered material. A wick (not shown in this figure) is provided. In each wick in the first evaporator 1a and the second evaporator 1b, the average hole radius of the surface of the stainless sintered material, the aperture ratio of the surface of the stainless sintered material, and the latent heat of water evaporation The surface area of the wick is adjusted so that the contact angle θ shown in FIG. 2 is the smallest and the capillary force ΔP is the largest when the amount of heat generated by the CPU 20 supplied to each evaporator is 60 W. Yes.

  The first evaporator 1a of the loop heat pipe on the left side of the figure is connected to a loop-shaped copper pipe that is hollow inside and returns to the first evaporator 1 from the first evaporator 1a. And the structure which the working fluid used as a heat transport material can move in the inside of this pipe is realized. The middle part of the pipe is a place for receiving air from the first fan 6a having a diameter of 60 mm, and copper radiating fins are installed inside the pipe at this place. In this way, the tube at the location that receives the air from the first fan 6a is the first condenser 5a, vaporized by the first evaporator 1a, and passed through the first evaporation tube 4a, which is a part of the tube. The working fluid 100 that has moved to the first condenser 5a is cooled and liquefied by the air blown from the first fan 6a. Note that the wind from the first fan 6 a that has been used for cooling and becomes warm air is discharged to the outside of the computer 1000. Here, the length of the 1st condenser 5a along the direction through which the working fluid 100 flows is 80 mm, and the distance between the 1st evaporator 1a and the 1st condenser 5a is about 300 mm. The working fluid 100 liquefied by the first condenser 5a returns to the first evaporator 1a through the first liquid pipe 2a which is a part of the pipe. In the wick of the first evaporator 1a, vaporization is performed again in the same manner as described above with reference to FIG. Here, a copper first heat conduction block 9a is provided in the middle of the first evaporation pipe 4a, and a first reservoir tank 7a is provided in the middle of the first liquid pipe 2a. Further, a first Peltier module 8a is provided between the first heat conduction block 9a and the first reservoir tank 7a.

  FIG. 6 is a view showing the first Peltier module 8a provided in the left loop heat pipe of FIG.

  The first Peltier module 8a is a planar electric element module, and includes a Peltier element that absorbs heat from one surface and dissipates heat from the other surface when a current flows. In general, in a Peltier device, the heat absorption surface that absorbs heat and the heat release surface that releases heat are determined according to the direction of the current flowing through the Peltier device, and heat absorption is achieved by changing the direction of the current. The surface and the heat dissipation surface are interchanged. In the first Peltier module 8a of FIG. 6, a surface (steam tube side surface) 81a facing the steam pipe side of the two surfaces of the first Peltier module 8a is in contact with the heat conduction block 9a. The surface (liquid tube side surface) 82a facing the liquid tube side of the surface is in contact with the reservoir tank 7a, and the vapor tube side surface 81a and the liquid tube side surface 82a function as a heat absorption surface or a heat release surface. To do. In a situation where the steam pipe side surface 81a is a heat release surface and the liquid pipe side surface 82a is a heat absorption surface, the first steam pipe 4a is heated through the heat conduction block 9a and the first through the reservoir tank 7a. The liquid pipe 2a is cooled. On the other hand, in a situation where the steam pipe side surface 81a is a heat absorption surface and the liquid pipe side surface 82a is a heat release surface, the first steam pipe 4a is cooled via the heat conduction block 9a and also via the reservoir tank 7a. The first liquid pipe 2a is heated.

  Returning to FIG.

  The right loop heat pipe of FIG. 5 has the same configuration as the left loop heat pipe described above. That is, the second evaporator 1b of the right loop heat pipe is also provided with the same pipe as the above-described left loop heat pipe that exits the first evaporator 1a and returns to the first evaporator 1. This pipe receives the air from the second steam pipe 4b and the second fan 6b through which the working fluid 100 vaporized in the first evaporator 1a moves, and the second condenser in which the working fluid 100 changes from the gas phase to the liquid phase. 5b functions as a second liquid pipe 2b through which the working fluid 100 liquefied by the second evaporator 5b moves. Also in the loop heat pipe on the right side of FIG. 5, a second heat conduction block 9b is provided in the middle of the second evaporation pipe 4b, and a second reservoir tank 7b is provided in the middle of the second liquid pipe 2b. A second Peltier module 8b is provided between the heat conducting block 9b and the second reservoir tank 7b. The second heat conduction block 9b, the second reservoir tank 7b, and the second Peltier module 8b are the first heat conduction block 9a, the first reservoir tank 7a, and the first Peltier of the left loop heat pipe described above. This is the same as the module 8a.

  Next, control of two loop heat pipes performed by the cooling device 200 of FIG. 5 will be described.

  The cooling device 200 includes a wattmeter 11 that detects the amount of heat generated by the CPU 20 and a control circuit 10 that controls the operation and stop of the two loop heat pipes. The wattmeter 11 is an electronic circuit that obtains the voltage supplied to the CPU 20 and the number of clocks of the CPU 20 during operation, and obtains the heat generation amount (unit: W (watt)) of the CPU 20 based on these pieces of information. The control circuit 10 controls the direction of the current flowing through the first Peltier module 8a and the second Peltier module 8b according to the detection result of the wattmeter 11, thereby realizing the operation and stop of the two loop heat pipes. Let Specifically, when the detection result of the wattmeter 11 indicates that the amount of heat generated by the CPU 20 exceeds 60 W, the control circuit 10 and the right side of FIG. If the detection result of the wattmeter 11 indicates that the heat generation amount of the CPU 20 is 60 W or less, the operation of the left loop heat pipe in FIG. 5 is stopped. Operate only the right loop heat pipe.

  Here, when the operation of the left loop heat pipe in FIG. 5 is stopped, the control circuit 10 causes the steam pipe side surface 81a in FIG. 6 to be a heat absorption surface and the liquid pipe side surface 82a to be a heat release surface. The current flowing through the first Peltier module 8a is controlled. In this situation, the first vapor pipe 4a is cooled via the heat conduction block 9a, so that a part of the gas-phase working fluid 100 passing through the first vapor pipe 4a reaches the first condenser 5a. It turns into a liquid phase before. Furthermore, in this situation, when the first liquid pipe 2a is heated via the reservoir tank 7a, a part of the liquid-phase working fluid 100 passing through the first liquid pipe 1a reaches the first evaporator 5a. Change to the gas phase before. As a result, it becomes difficult for the working fluid 100 to flow in one direction, and the circulation of the working fluid 100 eventually stops.

  Further, when the left loop heat pipe is operated, the control circuit 10 causes the first Peltier module 8a to have the steam pipe side surface 81a shown in FIG. 6 as a heat release surface and the liquid pipe side surface 82a as a heat absorption surface. To control the current flowing through In this situation, the first vapor pipe 4a is heated through the heat conduction block 9a, so that the gas-phase working fluid 100 can easily flow through the first vapor pipe 4a, and the first liquid pipe through the reservoir tank 7a. By cooling 2a, the liquid-phase working fluid 100 can easily flow through the first liquid pipe 2a. As a result, a state in which the working fluid 100 flows in one direction as shown in FIG. 1 is realized.

  Next, the working fluid 100 in the gas phase and the working fluid 100 in the liquid phase in the wicks in the first evaporator 5a and the second evaporator 5b under the above-described control performed according to the heat generation amount of the CPU 20 The state of the boundary surface between will be described.

  FIG. 7 is a diagram schematically illustrating how the working fluid 100 progresses through the wick 3 and changes from the liquid phase to the gas phase under the above-described control performed according to the heat generation amount of the CPU 20.

  Part (a) of FIG. 7 shows the state of the boundary surface between the gas-phase working fluid 100 and the liquid-phase working fluid 100 when the heat generation amount of the CPU 20 exceeds 60 W and the heat generation amount is large. In part (b) of FIG. 7, the gas phase working fluid 100 and the liquid phase working fluid 100 in a situation where the calorific value of the CPU 20 is 60 W or less and the calorific value is small are shown. The interface between the two is shown. Actually, the passages (cavities) in the wick 3 through which the liquid-phase working fluid 100 permeates are twisted and complicated, but in FIG. 7, the plurality of passages in the wick 3 ′ are It is schematically represented as a cylindrical passage that extends in parallel in the left-right direction. In this figure, the liquid-phase working fluid 100 advances to the right in the wick 3 by capillary force, and heat from the surroundings. To vaporize. Here, the relationship of the above-described equation (1) is established between the capillary force ΔPc and the contact angle θ formed by the wall surface of the cylindrical passage and the boundary surface.

  In a situation where the heat generation amount of the CPU 20 exceeds 60 W and the heat generation amount is large, the heat amount supplied to the first evaporator 1a and the second evaporator 1b is large, and in the wick 3 in each evaporator, FIG. As shown in part (a), the contact angle θ is small and the capillary force ΔPc is sufficiently large.

  On the other hand, in a situation where the heat generation amount of the CPU 20 is 60 W or less and the heat generation amount is small, the left loop heat pipe of FIG. 5 having the first evaporator 1a stops operating, and the left loop heat pipe carries heat. Is not done. For this reason, almost all the heat supplied from the CPU 20 is supplied to the second evaporator 1b of the right loop heat pipe in FIG. As a result, the wick 3 in the second evaporator 1b is shown in part (b) of FIG. 7 as compared with the case where a small amount of heat generated from the CPU 20 is distributed between the first evaporator 1a and the second evaporator 1b. Thus, a state where the contact angle θ is small and the capillary force ΔPc is large is realized.

  If a small amount of heat generated from the CPU 20 is distributed between the first evaporator 1a and the second evaporator 1b, the wick 3 of both evaporators has a large contact angle θ and a small capillary force ΔPc. It is difficult for the working fluid 100 to move in the vicinity of the wick 3, and the circulation speed of the working fluid 100 decreases. In such a state, even if the heat generation amount of the CPU 20 is small, the temperature around the CPU 20 gradually increases, and there is a possibility that a malfunction may occur in the electronic components around the CPU 20. In particular, in a situation where the circulation speed of the working fluid is completely zero in both of the two loop heat pipes, a so-called dryout occurs in which the working fluid supplied to each evaporator is insufficient, The temperature rise becomes serious.

  Therefore, as described above, by stopping the operation of the right side loop heat pipe in FIG. 5 and concentrating a small amount of heat generated from the CPU 20 on the second evaporator 1b of the right side loop heat pipe in FIG. With respect to the loop heat pipe on the right side of FIG. 5, a decrease in the mobility of the working fluid 100 in the vicinity of the wick 3 is avoided, and a decrease in the circulating speed of the working fluid is suppressed. At this time, due to the operation of the right loop heat pipe, the heat from the CPU 20 is efficiently carried out of the computer 1000, and the operation of the computer 1000 is maintained in a good state.

  Here, if the right side loop heat pipe of FIG. 5 is used in a concentrated manner, the right side loop heat pipe may wear more than the left side loop heat pipe of FIG. For this reason, the progress of such wear can be weakened by using the right and left loop heat pipes interchangeably. As shown in FIG. 5, since the cooling device 200 includes Peltier modules in both the left and right loop heat pipes in FIG. 5, the above replacement is performed by the control circuit 10. This is achieved by replacing the target Peltier module. When the wear of the loop heat pipe is sufficiently slow, as described above, the first Peltier module 8a of the left loop heat pipe in FIG. 5 is controlled, and the second Peltier module is changed from the right loop heat pipe in FIG. The cooling device 200 may be used in a state where 8b is removed.

  Next, an embodiment different from the embodiment described above will be described.

  FIG. 8 is a diagram illustrating a computer 2000 that is another embodiment of the electronic apparatus, and a cooling device 300 provided in the computer 2000.

  In the cooling device 300 of FIG. 8, the same components as those of the cooling device 200 shown in FIG. 5 are denoted by the same reference numerals, and redundant description of the components is omitted. Here, the cooling device 300 of FIG. 8 corresponds to another embodiment of the cooling device described above for the basic mode.

  The computer 2000 and the cooling device 300 in FIG. 8 are different from the computer 1000 and the cooling device 200 in FIG. 5 in that the first Peltier module 8a and the second Peltier module 8b in FIG. The control circuit 10 controls the first fan 6a (and the second fan 6b) instead of controlling the first Peltier module 8a (and the second Peltier module 8b). Except for this point, the computer 1000 and the cooling device 200 in FIG. 5 are the same as the computer 2000 and the cooling device 300 in FIG. 8, and the following description focuses on the different points.

  In the cooling device 300 of FIG. 8, when the detection result of the wattmeter 11 indicates that the heat generation amount of the CPU 20 exceeds 60 W, the control circuit 10 causes the first fan 6a and the second fan 6 of FIG. When both the fans 6b are rotated and the detection result of the wattmeter 11 indicates that the heat generation amount of the CPU 20 is 60 W or less, the rotation of the first fan 6a is stopped and only the second fan 6b is turned on. Rotate.

  In a situation where the rotation of the first fan 6a is stopped, the working fluid 100 which is not liquefied by the first condenser 5a because the working fluid 100 in the gas phase is not sufficiently cooled in the first condenser 5a of the left root heat pipe in FIG. 100 is present, and the circulation of the working fluid 100 is eventually stopped due to the shortage of the working fluid 100 in the liquid phase. As a result, a state in which only the root heat pipe on the right side of FIG. 8 is operating is realized.

  When the left loop heat pipe in FIG. 8 is operated, the control circuit 10 rotates the first fan 6a in FIG. 8 to cool the first condenser 5a. By so doing, the cooling of the gas-phase working fluid 100 proceeds in the first condenser 5a so that the working fluid 100 can easily flow in one direction, and the left loop heat pipe is operated.

  Here, in the cooling device 300 of FIG. 8, the air volume at the time of rotation of each fan is controlled to change according to the heat generation amount of the CPU 20.

  FIG. 9 is a diagram showing a change in the air volume of each fan in accordance with the heat generation amount of the CPU 20.

  As shown in this figure, when the heat generation amount of the CPU 20 is 60 W or less, only the second fan 6b rotates, and the air volume increases in proportion to the heat generation amount of the CPU 20. When the heat generation amount of the CPU 20 exceeds 60 W, the air volume of the second fan 6 b is maintained at the air volume when the heat generation amount of the CPU 20 is 60 W, while the air volume of the first fan 6 a is the total heat generation of the CPU 20. It increases in proportion to the amount of heat of the difference obtained by subtracting 60 W from the amount.

  As described above, the control circuit 10 controls the air volume of the first fan 6a and the second fan 6b according to the heat generation amount of the CPU 20, so that the cooling device 300 in FIG. 8 has a circulation speed according to the heat generation amount. The CPU 20 is cooled. In this control, even when the amount of heat generated by the CPU 20 is small, a decrease in the mobility of the working fluid 100 in the vicinity of the wick 3 is avoided, and a decrease in the circulating speed of the working fluid is suppressed. As a result, the operation of the computer 2000 is maintained in a good state.

  Next, the cooling effect of the cooling device 200 of FIG. 5 and the cooling device 300 of FIG. 8 described above will be described based on specific experimental results.

  In this experiment, by using the conventional cooling device 200 ′ of FIG. 2, the cooling device 200 of FIG. 5, and the cooling device 300 of FIG. ) Was measured while changing the amount of heat generated by the CPU 50. In this experiment, the surface area of the wick in the evaporator of the conventional cooling device 200 ′ of FIG. 2 is the same as the surface area of the wick in the two evaporators of the cooling device 200 of FIG. 5 and the cooling device 300 of FIG. The liquid pipe, steam pipe, and condenser of the conventional cooling device 200 ′ have the same material and the same size as the liquid pipe, steam pipe, and condenser of the cooling device 200 of FIG. 5 and the cooling device 300 of FIG. Adopted the same thing.

  FIG. 10 is a diagram showing experimental results.

  As shown in this figure, in the cooling device 200 of FIG. 5 and the cooling device 300 of FIG. 8, even though the heat generation amount of the CPU 50 increases, the value of the thermal resistance is maintained at a substantially constant low value. In the conventional cooling device 200 ′ of FIG. 2, when the heat generation amount of the CPU 50 is 60 W or less, the value of the thermal resistance increases rapidly. This rapid increase in thermal resistance corresponds to dryout occurring in the evaporator in the conventional cooling device 200 '. From this experimental result, when the heat generation amount of the CPU 50 is low, the operation of some of the heat loop pipes is stopped and only the remaining heat loop pipes are operated as in the cooling device 200 of FIG. 5 and the cooling device 300 of FIG. By doing so, it can be seen that dryout is avoided.

  The above is the description of the embodiment.

  In the above description, the cooling device including two heat loop pipes has been described. However, the cooling device and electronic device described above in the basic form are a cooling device and electronic device including three or more heat loop pipes. Also good.

  Hereinafter, various forms of the present case will be additionally described.

(Appendix 1)
An evaporator having a wick composed of a porous material, the liquid phase working fluid passing through the wick being evaporated by heat received from a heating element;
A condenser that releases heat of the gas-phase working fluid to condense the working fluid;
A vapor pipe that connects the evaporator and the condenser and moves a vapor-phase working fluid evaporated in the evaporator from the evaporator to the condenser;
The evaporator and the condenser are connected, and a liquid pipe for moving the liquid-phase working fluid condensed in the condenser from the condenser to the evaporator is provided, and each evaporator serves as a common heating element. A plurality of loop heat pipes that are thermally coupled;
A calorific value detection means for detecting the calorific value of the heating element;
A cooling apparatus comprising: a switching control unit that performs switching control of operation and stop of the plurality of loop heat pipes according to a heat generation amount detected by the heat generation amount detection unit.

(Appendix 2)
At least one loop heat pipe of the plurality of loop heat pipes is provided with a temperature adjusting unit that heats and cools the steam pipe of the loop heat pipe and / or heats and cools the liquid pipe of the loop heat pipe. It is equipped with
The switching control unit controls the temperature adjusting unit to cool the steam pipe of the loop heat pipe including the temperature adjusting unit and / or to heat the liquid pipe of the loop heat pipe. The operation of the loop heat pipe is stopped, and the loop heat pipe is operated by heating the steam pipe of the loop heat pipe and / or cooling the liquid pipe of the loop heat pipe. The cooling device according to appendix 1.

(Appendix 3)
The cooling device according to appendix 2, wherein the temperature adjusting unit includes a Peltier element.

(Appendix 4)
The Peltier device has two surfaces, a heat absorption surface that absorbs heat and a heat discharge surface that discharges heat, and the heat absorption surface and the heat discharge surface are switched according to the direction of the current flowing through the Peltier device. One surface of the Peltier element is in contact with a steam pipe of a loop heat pipe provided with the temperature adjustment unit, and the other surface of the Peltier element is an element of the loop heat pipe provided with the temperature adjustment unit. Is in contact with the liquid pipe,
The switching control unit switches and controls the operation and stop of the loop heat pipe provided with the temperature adjusting unit by controlling the direction of the current flowing through the Peltier element. Cooling system.

(Appendix 5)
The cooling device according to claim 1, wherein the switching control unit operates only a smaller number of loop heat pipes as the calorific value detected by the calorific value detection means decreases.

(Appendix 6)
At least one loop heat pipe of the plurality of loop heat pipes includes a blower that blows air toward a condenser of the loop heat pipe,
The cooling device according to claim 1, wherein the switching control unit switches and controls the operation and stop of a loop heat pipe provided with the blower by controlling an air volume of the blower.

(Appendix 7)
The cooling device according to claim 6, wherein the switching control unit operates only a smaller number of loop heat pipes as the heat generation amount detected by the heat generation amount detection means is smaller.

(Appendix 8)
An electronic device provided with a heat generating electronic component that generates heat by operation,
An evaporator having a wick composed of a porous material, and evaporating a liquid-phase working fluid passing through the wick by heat received from the heat-generating electronic component;
A condenser that releases heat of the gas-phase working fluid to condense the working fluid;
A vapor pipe that connects the evaporator and the condenser and moves a vapor-phase working fluid evaporated in the evaporator from the evaporator to the condenser;
The evaporator and the condenser are connected, and a liquid pipe for moving the liquid-phase working fluid condensed in the condenser from the condenser to the evaporator is provided, and each evaporator serves as a common heating element. A plurality of loop heat pipes that are thermally coupled;
A heat generation amount detecting means for detecting a heat generation amount of the heat generating electronic component;
An electronic apparatus comprising: a switching control unit that performs switching control of operation and stop of the plurality of loop heat pipes in accordance with a heat generation amount detected by the heat generation amount detection unit.

It is a schematic block diagram showing the structure and operating principle of a loop heat pipe. It is the figure which represented typically a mode that a working fluid progressed in a wick and changed from a liquid phase to a gaseous phase. It is a figure which shows the conventional cooling device provided in the computer. It is a figure showing the mode of the boundary surface of the liquid side and the vapor | steam side according to the emitted-heat amount of a heat generating body. It is a figure which shows the computer which is embodiment of an electronic device, and the cooling device with which this computer is equipped. It is the figure showing the 1st Peltier module with which the left loop heat pipe of FIG. 5 is equipped. It is the figure which represented typically a mode that a working fluid progressed in the wick and changed from a liquid phase to a gaseous phase under the above-mentioned control performed according to the emitted-heat amount of CPU. It is a figure which shows the computer which is another embodiment of an electronic device, and the cooling device provided in this computer. It is a figure showing the change of the air volume of each fan according to the emitted-heat amount of CPU. It is a figure showing an experimental result.

Explanation of symbols

101,1 'evaporator 1a first evaporator 1b second evaporator 102, 2' liquid pipe 2a first liquid pipe 2b second liquid pipe 103, 3 ', 3 wick 104, 4' steam pipe
4a 1st steam pipe 4b 2nd steam pipe 105, 5 'Condenser 5a 1st condenser 5b 2nd condenser 6' Fan 6a 1st fan 6b 2nd fan 7 'Reservoir tank 7a 1st reservoir tank 7b 2nd reservoir Tank 8a First Peltier module 81a Steam pipe side face 82a Liquid pipe side face 8b Second Peltier module 9a First heat conduction block 9b Second heat conduction block 10 Control circuit 11 Watt meter 20 CPU
200 ', 200, 300 Cooling device 1000', 1000, 2000 Computer

Claims (1)

An evaporator having a wick composed of a porous material, the liquid phase working fluid passing through the wick being evaporated by heat received from a heating element;
A condenser that releases heat of the gas-phase working fluid to condense the working fluid;
A vapor pipe that connects the evaporator and the condenser and moves a vapor-phase working fluid evaporated in the evaporator from the evaporator to the condenser;
The evaporator and the condenser are connected, and a liquid pipe for moving the liquid-phase working fluid condensed in the condenser from the condenser to the evaporator is provided, and each evaporator serves as a common heating element. A plurality of loop heat pipes that are thermally coupled;
A calorific value detection means for detecting the calorific value of the heating element;
A blower for blowing air toward a condenser of at least one loop heat pipe of the plurality of loop heat pipes;
Switching for controlling switching between operation and stop of a loop heat pipe provided with a condenser blown by the blower by controlling the air flow of the blower in accordance with the heat generation amount detected by the heat generation amount detection means A cooling device comprising a control unit .

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