JP5061911B2 - Loop heat pipe and electronic equipment - Google Patents

Description

  The present invention relates to, for example, a loop heat pipe used for cooling a heat generating element in an electronic device such as a computer, and an electronic device equipped with such a heat pipe.

  Conventionally, as a cooling method for cooling a heated object, various cooling methods such as a simple air cooling method, a water cooling method, and an electric cooling method using a Peltier element (for example, see Patent Document 1) are known. It has been. Among such cooling methods, there is a cooling method using a so-called heat pipe (see, for example, Patent Document 2). A heat pipe is a heat transfer device that transports heat using a phase change of a working fluid sealed inside, and is widely used to cool a heat generating element in an electronic device such as a computer.

  As a kind of this heat pipe, an evaporator that receives heat from the outside and evaporates the liquid-phase working fluid to change into a vapor-phase working fluid, and heat radiation condenses the vapor-phase working fluid to the liquid-phase. There are known loop type heat pipes including a condenser that changes the phase of the working fluid into a working fluid and a pipe that circulates the working fluid between the evaporator and the condenser (for example, Patent Document 3, Patent Document 4, And Patent Document 5). The loop heat pipe is being developed mainly as a heat transport device such as an artificial satellite or a space station.

  FIG. 11 is a schematic configuration diagram illustrating an example of a conventional loop heat pipe.

  FIG. 11 shows an evaporator 10 that receives heat from the outside and evaporates the liquid-phase working fluid to change into a vapor-phase working fluid, and heat radiation condenses the vapor-phase working fluid to form a liquid-phase working fluid. A loop heat pipe 1 including a condenser 20 that changes the phase to a working fluid and a pipe 30 that circulates the working fluid between the evaporator 10 and the condenser 20 is shown.

  The evaporator 10 of the loop heat pipe 1 is provided with a cylindrical evaporator 11, and a plurality of groove-shaped steam passages 13 extending in the axial direction are formed on the inner wall of the evaporator 11. . And the porous cylindrical wick 12 is inserted so that the front-end | tip part of this vapor | steam channel | path 13 may be contact | connected.

  The liquid-phase working fluid fed from the pipe 30 into the wick 12 penetrates from the fine holes on the inner wall of the wick 12 to the outside of the wick 12 and reaches the vapor passage 13. At this time, when the evaporator 11 is heated by the heating element, the liquid-phase working fluid that reaches the vapor passage 13 from the wick 12 evaporates to generate a vapor-phase working fluid. Since the heat of the heating element is used for the phase change in the evaporator 11, the heating element is cooled. The vapor-phase working fluid generated by cooling goes to the condenser 20 and is cooled by the condenser 20 to be changed into a liquid-phase working fluid. By repeating such a circulation of the working fluid, the heating element is continuously cooled.

  Here, not only the loop type heat pipe 1 shown in FIG. 11 but generally the loop type heat pipe has an evaporator at a lower position than the condenser as shown in FIG. It is assumed that it is used in the state of heated bottom heat. This is because, since the evaporator is heated by the heating element to be cooled and the circulation of the working fluid is started, at the time of this start, the liquid-phase working fluid has reached the vapor passage from inside the wick. This is because the liquid-phase working fluid needs to evaporate. If the loop heat pipe is used in a state of top heat that is upside down from FIG. 11, the working fluid is biased toward the condenser due to gravity at the start of circulation of the working fluid. Therefore, at this time, there is a dry-out state in which there is no liquid-phase working fluid to be evaporated by heating, and there is a problem that the circulation of the working fluid does not start. In addition, even when the loop heat pipe is used in a horizontal position, there is no guarantee that there is sufficient liquid-phase working fluid in the evaporator at the start of the working fluid circulation. There is a possibility that the problem that the working fluid circulation does not start due to dryout may occur.

  However, due to mounting restrictions in electronic devices, loop heat pipes may be forced to be mounted on electronic devices in a state where they are used in a top heat or arranged horizontally, such as top heat. A loop-type heat pipe that can start the circulation of the working fluid even in a state is desired.

  Therefore, in order to enable the circulation of the working fluid in a state of top heat or the like, for example, the liquid-phase working fluid biased toward the condenser is forcibly heated at the start of the working fluid circulation. A technique has been proposed in which dry-out is eliminated by pushing up the liquid-phase working fluid biased toward the condenser to the evaporator by the vapor pressure generated by the heating (see, for example, Patent Document 6).

  FIG. 12 is a diagram schematically illustrating an example of a technique for eliminating dry-out in a state such as top heat by forcibly heating a liquid-phase working fluid biased toward the condenser side.

  The loop heat pipe 2 shown in FIG. 12 includes a condenser 40 having radiating fins 41, an evaporator 60 in contact with a heating element 50 to be cooled, and a vapor phase working fluid generated in the evaporator 60. A vapor pipe 70 that guides the liquid-phase working fluid generated in the condenser 40 to the evaporator 60, and forced heating of the liquid-phase working fluid that is biased toward the condenser 40. The heating part 90 to perform is provided. The heating unit 90 includes a heater 91 attached to the steam pipe 70 in the vicinity of the condenser 40, a power source 92 that supplies power to the heater 91, a switch 93 provided on a circuit from the power source 92 to the heater 91, And a control device 94 that turns on the switch 93 for a predetermined time after the heating element 50 starts operating. In addition, a porous filter 95 is attached in the vicinity of the heater 91 on the evaporation unit 60 side in the steam pipe 70.

For example, when the loop heat pipe 2 is used in a top heat as shown in FIG. 12, the liquid-phase working fluid is biased toward the condenser 40 at the start of circulation of the working fluid. At this time, when the heating element 50 starts operating and starts to generate heat, the control device 94 turns on the switch 93 and the heater 91 is in the liquid phase in the steam pipe 70 where the heater 91 is attached. The working fluid in the liquid phase is heated to evaporate. The vapor-phase working fluid generated by the evaporation is blocked by the filter 95 and travels toward the liquid pipe 80 without flowing back through the vapor pipe 70. As a result, a pressure is generated to push up the liquid-phase working fluid toward the liquid pipe 80, and the liquid-phase working fluid is pushed up to the evaporation unit 60 by this pressure. Thereby, the dry-out in the evaporation part 60 is eliminated, and the circulation of the working fluid is started.
Japanese Patent Laid-Open No. 10-244251 JP-A-11-201669 US Pat. No. 4,765,396 JP 2002-174492 A JP 2003-148882 A Japanese Patent Laid-Open No. 2002-340489

  Here, in the technique shown in FIG. 12 as an example, a filter as shown in FIG. 12 is required in order to prevent the vapor-phase working fluid generated by forced heating from flowing back in the steam pipe. . However, such a filter becomes a resistance that hinders normal circulation when the working fluid circulates normally. For example, when the heat generation in the heat generating element to be cooled decreases, the amount of vapor-phase working fluid generated in the evaporator decreases, so the force that pushes the liquid-phase working fluid from the condenser to the evaporator is increased. Decrease. At this time, the filter as described above further reduces this small force, and as a result, the force that pushes the liquid-phase working fluid to the evaporator is unacceptably reduced, resulting in dryout during circulation. May occur and the circulation may stop.

  In view of the above circumstances, the present invention provides a loop heat pipe capable of starting the circulation of a working fluid in a state of top heat or the like so as not to hinder the circulation after the circulation starts, and such a loop. An object of the present invention is to provide an electronic device equipped with a mold heat pipe.

The basic form of the first loop type heat pipe among the loop type heat pipes that achieve the above object is as follows:
A steam pipe that connects the evaporator and the condenser, and a liquid pipe that connects the condenser and the evaporator are connected in a loop, and a loop heat pipe in which the working fluid passes through the liquid pipe. There,
Control means for controlling the circulation of the working fluid,
The control means includes means for cooling the working fluid in the liquid pipe at the time of starting to start the circulation.

  According to the basic form of the first loop heat pipe, the working fluid in the liquid pipe is cooled at the time of starting to start the circulation. Here, generally, the inside of the loop heat pipe is maintained at a saturated vapor pressure. Therefore, this loop heat pipe is used in a top heat state, etc., and the liquid-phase working fluid is biased to the condenser side at the time of the start-up, and in the liquid pipe that guides the liquid-phase working fluid to the evaporator Even if most of the vapor phase working fluid is occupied and dried out, the above cooling causes the temperature of the vapor phase working fluid in the liquid pipe to change, for example, the working fluid in other parts such as the vapor pipe. When the temperature is lower than the above temperature, a condensing action occurs in the liquid pipe, and a liquid-phase working fluid is generated. The dry-out is eliminated by the liquid-phase working fluid generated by the cooling, and the circulation of the working fluid is started. Further, according to this basic form, since the dry-out is eliminated by cooling the working fluid in the liquid pipe, a special element that prevents the circulation after the start of circulation, such as a filter, is unnecessary. That is, according to the basic form of the first loop heat pipe, the circulation of the working fluid can be started in a state of top heat or the like so as not to disturb the circulation after the circulation is started.

The basic form of the second loop heat pipe among the loop heat pipes that achieve the above object is as follows:
An evaporator, a condenser, a vapor pipe connecting the evaporator and the condenser, and a liquid pipe connecting the condenser and the evaporator are connected in a loop, and a loop through which the working fluid passes. Type heat pipe,
First temperature difference detecting means for detecting a temperature difference between the steam pipe and the liquid pipe;
And adjusting means for increasing the temperature of the steam pipe and lowering the temperature of the liquid pipe when the temperature difference is smaller than a predetermined first value.

  Generally, when dry out occurs in a loop heat pipe and both the steam pipe and the liquid pipe are occupied by the working fluid in the vapor phase, the steam pipe and the liquid pipe have substantially the same temperature. In other words, if there is a certain temperature difference between the steam pipe and the liquid pipe, there is a high possibility that dryout has not occurred. Conversely, if this temperature difference is abnormally small, dryout will occur. It is highly possible that Here, the first value is a value determined in advance as a lower limit value of the temperature difference between the steam pipe and the liquid pipe in a state where dryout has not occurred. According to the basic form of the second loop heat pipe, when the temperature difference between the steam pipe and the liquid pipe is smaller than the first value and the occurrence of dryout is assumed, the steam pipe And the temperature of the liquid pipe is lowered. As a result, the temperature of the vapor-phase working fluid that occupies most of the liquid pipe by dryout becomes lower than the temperature of the working fluid in the steam pipe, and a condensation action occurs in the liquid pipe to generate a liquid-phase working fluid. Will be. Then, the dry-out is eliminated by the liquid-phase working fluid, and the circulation of the working fluid is started. Further, according to this basic form, since the dry-out is eliminated by the rise of the temperature of the steam pipe and the fall of the temperature of the liquid pipe, the circulation is hindered after the start of circulation such as the above-mentioned filter. Such special elements are not necessary. That is, according to the basic form of the second loop type heat pipe, the circulation of the working fluid can be started in a state of top heat or the like so as not to disturb the circulation after the circulation is started.

In addition, for the basic form of the second loop heat pipe,
The application form that “the adjusting means is a mechanism including a Peltier element disposed between the steam pipe and the liquid pipe” is suitable, and for this preferred application form,
An application mode in which “one surface of the Peltier element is in contact with the surface of the steam pipe and the other surface of the Peltier element is in contact with the surface of the liquid pipe” is more preferable.

  According to these application forms, the temperature of the liquid pipe can be easily lowered by the Peltier element, and according to the further preferable application form, the temperature of the liquid pipe can be lowered by the Peltier element. The steam pipe temperature can be increased at the same time.

In addition, for the basic form of the second loop heat pipe,
“The first temperature difference detecting means detects the temperature difference indirectly by detecting both the temperature of the steam pipe and the temperature of the liquid pipe and obtaining the difference between the two temperatures. The application form “is” is also suitable.

  According to this preferred application mode, the temperature difference can be easily detected.

In addition, for the basic form of the second loop heat pipe,
“The evaporator is heated by a heating element that generates heat when supplied with electric power,
The adjusting means raises the temperature of the steam pipe and lowers the temperature of the liquid pipe when the temperature difference is smaller than the first value when power is supplied to the heating element. The application form “is” is also suitable.

  When the loop heat pipe is used in a state of top heat or the like, it is highly likely that dryout has occurred at the time when electric power is supplied to the heating element and the working fluid is started. According to the above preferred application mode, the dryout at this point is effectively eliminated, which is efficient.

For this preferred application,
“It further has a second temperature difference detecting means for detecting a temperature difference between the liquid pipe and the condenser,
The adjusting means is a case where a temperature difference between the steam pipe and the liquid pipe is smaller than the first value at the time when electric power is supplied to the heating element. The application form of “increasing the temperature of the steam pipe and lowering the temperature of the liquid pipe when the temperature difference from the vessel is smaller than a predetermined second value” is further preferable.

  In the loop heat pipe, when the circulation of the working fluid starts, the temperature of the liquid pipe becomes lower than the temperature of the condenser in which the ratio of the vapor-phase working fluid is higher than that of the liquid pipe. In other words, if there is a certain temperature difference between the liquid pipe and the condenser, there is a high possibility that the working fluid has started to circulate sufficiently, and conversely, if this temperature difference is abnormally small, the working fluid It is likely that has not yet begun to circulate sufficiently. Here, the second value is a value that is determined in advance as a lower limit value of the temperature difference between the liquid pipe and the condenser in a state where the working fluid is sufficiently circulated. According to the preferred application mode, at the time when electric power is supplied to the heating element, that is, at the start of circulation, the temperature difference between the liquid pipe and the condenser is smaller than the second value, and the operation is performed. When it is assumed that the circulation of the fluid has not started yet, the temperature of the steam pipe is increased and the temperature of the liquid pipe is decreased, so that the circulation of the working fluid can be started more reliably.

In addition, for the basic form of the second loop heat pipe,
“The evaporator is heated by a heating element that generates heat when supplied with electric power,
The adjusting means raises the temperature of the steam pipe and lowers the temperature of the liquid pipe when the temperature difference is smaller than the first value when power is supplied to the heating element, While power is being supplied to the heating element, when the temperature difference is smaller than a predetermined third value, the temperature of the steam pipe is raised and the temperature of the liquid pipe is lowered. '' The application form is also suitable.

  Generally, when a working fluid is normally circulated in a loop heat pipe, a temperature difference of a certain degree or more exists between a steam pipe and a liquid pipe. In other words, if there is a certain temperature difference between the steam pipe and the liquid pipe, there is a high possibility that the working fluid is circulated normally. Conversely, if this temperature difference is abnormally small, dry out It is highly possible that this circulation has stopped. Here, the third value is a value predetermined as a lower limit value of the temperature difference between the steam pipe and the liquid pipe in a state where the working fluid is normally circulated. According to the preferred application mode, the dry-out at the start of the circulation of the working fluid is eliminated, and while the electric power is supplied to the heating element, that is, during the circulation of the working fluid, the steam pipe and the liquid pipe When the temperature difference is smaller than the third value and the circulation is stopped due to the dryout, the dryout is eliminated. Therefore, the circulation once stopped can be resumed.

For this preferred application,
“It further has a temperature detecting means for detecting the temperature of the heating element,
When the electric power is supplied to the heating element, the adjusting means is configured such that the temperature difference is larger than the third value when the temperature of the heating element exceeds a predetermined upper limit value. In a case where the temperature is small, the application mode of raising the temperature of the steam pipe and lowering the temperature of the liquid pipe is more preferable.

  According to this more preferred application mode, when the heat generating element is generating abnormal heat exceeding the upper limit value, and it is assumed that the circulation of the working fluid is stopped, the dry-out is eliminated, which is efficient. It is.

In addition, an electronic device that achieves the above-mentioned purpose is
A basic form of the first loop heat pipe, a basic form of the second loop heat pipe, and application forms of the second loop heat pipe are provided.

  According to these electronic devices, the circulation of the working fluid can be started in the state of top heat or the like with respect to the loop heat pipe provided in the electronic device so as not to disturb the circulation after the circulation is started.

  As described above, according to the basic form of the first and second loop heat pipes and the electronic apparatus, the working fluid is circulated in the state of top heat or the like after the circulation starts. You can start without disturbing.

  Specific embodiments of the loop heat pipe and the electronic device described above for the basic form and the application form will be described below with reference to the drawings.

  FIG. 1 is a perspective view of a computer which is a specific embodiment of an electronic device.

  FIG. 1 shows a computer 500 having a CPU 510 as a main heat generating unit, an HDD (Hard Disk Drive) 520 as an auxiliary storage device, a power source unit 530, and an air cooling fan 540, and the computer 500. A loop heat pipe 100 is shown that is incorporated and cools the CPU 510. This electronic device corresponds to an embodiment of the electronic device described above. The CPU 510 corresponds to an example of the heating element in the application mode described above.

  The loop heat pipe 100 corresponds to an embodiment that serves as both the first loop heat pipe and the second loop heat pipe, and receives a liquid-phase working fluid from the CPU 510 that is a heating element. By evaporating part 110 having a built-in evaporator (heat receiver) to be evaporated and changing the phase to a vapor phase working fluid, and having a plurality of radiating fins 121 and receiving air from the blower fan 540 by the radiating fins. A condenser (heat radiator) 120 that condenses the vapor-phase working fluid by heat radiation and changes the phase into a liquid-phase working fluid, and a copper pipe that guides the vapor-phase working fluid generated in the evaporator 110 to the condenser 120. A vapor pipe 130, a liquid pipe 140 that is a copper pipe that guides the liquid-phase working fluid generated in the condenser 120 to the evaporator 110, and a liquid-phase working fluid that has passed through the liquid pipe 140 are temporarily stored. After And a supply reservoir tank 150 to the calling unit 110.

  The loop heat pipe 100 covers the Peltier element 160 whose cooling part is in contact with the reservoir tank 150 and the steam pipe 130 in the vicinity of the outlet of the vapor-phase working fluid in the evaporation part 110, and the heating part of the Peltier element 160 A heat conduction block 170 in contact with the.

Further, the loop heat pipe 100 includes a first temperature sensor 181 that detects the temperature T _cpu of the CPU 510, a second temperature sensor 182 that detects the temperature T _tank of the reservoir tank 150, and the temperature T _{vp of the} heat conduction block 170. A third temperature sensor 183 for detecting the temperature, a fourth temperature sensor 184 for detecting the temperature T _cond of the condenser 120, and a control for controlling ON / OFF of the Peltier element 160 based on each temperature detected by each temperature sensor. Part 190.

  Here, the evaporation unit 110 corresponds to an example of an evaporator in each of the basic form of the first loop heat pipe and the basic form of the second loop heat pipe. The condenser 120 corresponds to an example of a condenser in each basic form, and the combination of the liquid pipe 140 and the reservoir tank 150 corresponds to an example of a liquid pipe in each basic form. The combination of the steam pipe 130 and the heat conduction block 170 corresponds to an example of the steam pipe in each basic form. The combination of the control unit 190 and the Peltier element 160 corresponds to an example of control means in the basic form of the first loop heat pipe described above, and the Peltier element 160 includes the first loop described above. This corresponds to an example of “means for cooling the working fluid in the liquid pipe” in the basic form of the mold heat pipe. The combination of the Peltier element 160 and the control unit 190 corresponds to an example of the adjusting means in the basic form of the second loop heat pipe described above. The combination of the second temperature sensor 182, the third temperature sensor 183, and the control unit 190 corresponds to an example of the first temperature difference detection means in the basic form of the second loop heat pipe described above. To do. The combination of the second temperature sensor 182, the fourth temperature sensor 184, and the control unit 190 corresponds to an example of the second temperature difference detection means in the application form of the second loop heat pipe described above. And what combined the 1st temperature sensor 181 and the control part 190 is equivalent to an example of the temperature detection means in the application form of the 2nd loop type heat pipe mentioned above. In addition, the Peltier element 160 corresponds to an example of the Peltier element in the application form of the second loop heat pipe described above.

  In the loop heat pipe 100, water is used as a working fluid, and the inside of the steam pipe 130, the liquid pipe 140, and the like is set to a saturated vapor pressure of water. When the CPU 510 starts operating and generates heat, first, the liquid-phase working fluid is evaporated by the heat generated by the CPU 510 in the evaporation unit 110 in contact with the CPU 510 to generate a vapor-phase working fluid. This vapor-phase working fluid travels through the vapor pipe 130 to the condenser 120 where it is condensed by the condenser 120 and converted into a liquid-phase working fluid. The liquid-phase working fluid travels through the liquid pipe 140 and the reservoir tank 150 to the evaporation unit 110 and is evaporated again by the heat generated by the CPU 510. In the loop heat pipe 100, the CPU 510 is cooled by the circulation of the working fluid.

  FIG. 2 is a perspective view showing the structure of the evaporation section of the loop heat pipe shown in FIG.

  The evaporation unit 110 is incorporated in the computer shown in FIG. 1 and includes an intake manifold (branch unit) 111, three evaporators 112, an exhaust manifold (condensing unit) 113, an evaporator container 114, and a heat insulating material 115. And.

  The intake manifold 111 branches the liquid-phase working fluid sent from the condenser 120 (see FIG. 1) and flowing in from the liquid inlet 111a into three.

  Each of the three evaporators 112 is a dual type in which a porous cylindrical wick 112c is inserted into a copper pipe 112a that receives each of the liquid-phase working fluid branched by the intake manifold 111 and changes the phase into a vapor phase. These are tubular members arranged side by side in a tubular structure.

  Here, in this embodiment, the inner wall surface of the main body portion of the intake manifold 111 and the inner wall surface of the cylindrical liquid inlet 111a are covered with the wick 111b of the same quality as the wick 112c in the evaporator 112. The wick 111b in the intake manifold 111 plays a role of guiding the liquid-phase working fluid flowing in from the reservoir tank 150 shown in FIG. 1 to the evaporator 112 by capillary action in the porous structure. In contact with the wick 112c. By the action of the wick 111b in the intake manifold 111, even if a small amount of liquid-phase working fluid flows from the reservoir tank 150, the liquid-phase working fluid is reliably guided to the evaporator 112.

  The exhaust manifold 113 converges the vapor-phase working fluid that has flowed out of the three evaporators 112 and sends it to the condenser 120 (see FIG. 1) from the vapor outlet 113a.

  The evaporator accommodating body 114 accommodates the three evaporators 112, receives the heat of the CPU 510 from the lower surface, diffuses the received heat to the inside, and transfers the heat to the three evaporators 112.

  The heat insulating material 115 covers the upper surface of the evaporator housing 114 and suppresses heat radiation from the evaporator housing 114 to the outside to keep the temperature in the heat receiving portion uniform.

  The surface of the CPU 510 on the evaporation unit 110 side is a square of 30 mm length × 30 mm width, and the outer size of the evaporation unit 110 (not including the intake manifold 111 and the exhaust manifold 113) is 50 mm length × 50 mm width × 20 mm height. . The evaporator housing body 114 is a box made of a copper plate having a thickness of 2 mm and having a hollow inside.

  Inside the evaporator housing 114, three evaporators 112 penetrating in the plane direction are installed in parallel at equal intervals. Each of the three evaporators 112 has a double pipe structure including a copper pipe 112a having an outer diameter of 14 mm and a thickness of 2 mm and a porous wick 112c inserted into the copper pipe 112a.

  A cavity in the evaporator housing 114 is sealed by the evaporator housing 114 and the outer wall of the copper pipe 112a, and water as a working fluid is sealed in the cavity. The inside of this cavity is kept at the saturated water vapor pressure of water. Here, the working fluid (water) circulating inside the steam pipe 130, the liquid pipe 140, etc. in FIG. 1 is hereinafter referred to as a first working fluid, and the working fluid enclosed in the cavity is a second. Called the working fluid.

  Further, groove-shaped steam passages 112b having a depth of 1 mm in the axial direction are formed at equal intervals at a pitch of 2 mm on the inner walls of the three copper pipes 112a. A cylindrical wick 112c having an outer diameter of 10 mm and an inner diameter of 4 mm is inserted so as to be in contact with the tip of the steam passage 112b formed in the inner wall of the copper pipe 112a. The steam passage 112b formed in the inner wall of the copper pipe 112a functions as a passage through which the vapor phase working fluid flows.

  The wick 112c is a porous cylinder formed by sintering copper powder, and the inner side and the outer side of the wick 112c communicate with each other through fine holes having a diameter of 10 μm to 50 μm, and the first working fluid in the wick 112c. Oozes out of the wick 112c by capillary action.

  At both ends of the three copper pipes 112a, an intake manifold 111 for branching the liquid-phase first working fluid flowing in from the liquid pipe 140 and the reservoir tank 150 (see FIG. 1) to the three wicks 112c, An exhaust manifold 113 that converges the vapor-phase first working fluid flowing out from the vapor passages 112b of the three wicks 112c into one and sends it to the condenser 120 is joined, and the first working fluid leaks. It's not going out.

  The exhaust manifold 113 of the evaporator 110 and the condenser 120 are connected by a vapor pipe 130, and the condenser 120 and the intake manifold 111 of the evaporator 110 are connected by a liquid pipe 140 and a reservoir tank 150. The first working fluid circulates.

  In the present embodiment, the first working fluid and the second working fluid are sealed at different locations. Although water is used for both the first and second working fluids, fluids other than water may be used, and working fluids of different materials may be used. When enclosing the first working fluid and the second working fluid, the atmospheric pressure is adjusted so as to be the saturated vapor pressure of water.

  3 is a cross-sectional view of the evaporator shown in FIG. 2 cut in the axial direction of the evaporator, and FIG. 4 is a cross-sectional view of the evaporator shown in FIG. 2 cut in a direction orthogonal to the axial direction of the evaporator. is there.

  As shown in FIGS. 3 and 4, the evaporator 110 is covered with a metal evaporator housing 114, and thermal grease is applied to the lower surface 114a of the evaporator housing 114, via the thermal grease. Thus, the CPU 510 which is a heating element is in thermal contact with the lower surface 114a of the evaporator housing 114.

  In the present embodiment, the evaporator accommodating body 114 has an internal space 114b. The internal space 114b is changed to a vapor phase by receiving heat from the heating element, and is changed to a liquid phase by heat transfer to the evaporator 112. A changing second working fluid 118 is enclosed.

  Next, the operation of the evaporation unit 110 will be described.

  When the lower surface 114a of the evaporator housing 114 is heated by the CPU 510, the second working fluid 118 enclosed in the internal space 114b of the evaporator housing 114 is heated and boiled and vaporized.

  The vaporized second working fluid 118 in the vapor phase touches the surface of the copper pipe 112a having a low temperature to aggregate and liquefy, whereby heat from the CPU 510 is transferred to the copper pipe 112a.

  The heat transferred to the copper pipe 112a is transferred to the first working fluid 116 in the wick 112c inside the copper pipe 112a, and the first working fluid 116 boils and vaporizes.

  The vaporized first working fluid 117 in the vapor phase passes through the vapor passage 112b, is sent from the vapor outlet 113a through the exhaust manifold 113, and is supplied to the condenser 120 (see FIG. 1) through the vapor pipe 130 (see FIG. 1). Is done.

  The condenser 120 has a structure in which a plurality of heat dissipating fins 121 (see FIG. 1) are soldered to a copper tube in order to increase the heat dissipating area, and a blower fan 540 (FIG. 1) directed toward the heat dissipating fins 121. The heat of the vapor-phase first working fluid 116 in the copper pipe 300 is dissipated into the air by the air blowing from the reference). In this way, the vapor-phase first working fluid 116 aggregates and liquefies by releasing heat while passing through the condenser 120.

  The first working fluid 116 thus changed into the liquid phase again flows into the intake manifold 111 from the liquid inlet 111a through the liquid pipe 140 and the reservoir tank 150, and flows into the three copper pipes 112a through the intake manifold 111 to evaporate. The unit 110 receives the heat of the CPU 510 and becomes the vapor-phase first working fluid 116 and is sent to the condenser 120.

  Here, in the present embodiment, the second working fluid is used as the heat transfer method from the CPU 510 applied to the lower surface 114a of the evaporator housing 114 to the evaporator 112 in the evaporator 110. Although the method is adopted, this heat transfer method may be a method using heat conduction of metal as described below, for example.

  Hereinafter, another embodiment of the evaporation unit in which a method using heat conduction of metal is adopted as a heat transfer method from the lower surface of the evaporator housing to the evaporator 112 will be described.

  FIG. 5 is a perspective view showing the structure of another type of evaporation unit, FIG. 6 is a cross-sectional view of the evaporation unit of another type shown in FIG. 5 cut in the axial direction of the evaporator, and FIG. It is sectional drawing which cut | disconnected the evaporation part of another form shown in 5 in the direction orthogonal to the axial direction of an evaporator.

  In the evaporation unit 210 of another form shown in these drawings, the components excluding the evaporator container 114 are the same as the components of the evaporation unit 110 shown in FIGS. 2 to 3, and in FIGS. These constituent elements are denoted by the same reference numerals as those in FIGS. 2 to 3, and in the following, redundant description of these equivalent constituent elements will be omitted.

  The evaporator housing 211 provided in the evaporation unit 210 of this different form is a copper block, and has three cavities 211b in contact with the outer wall surfaces of the three evaporators 112, and each of the three cavities 211b. Each of the three evaporators 112 is accommodated.

  When the lower surface 211a of the evaporator housing 211 is heated by the CPU 510, the heat from the CPU 510 is transmitted to the copper block of the evaporator housing 211 and further transmitted to the copper pipe 112 via the copper block. As described above, in this another form of the evaporation section 210, a method using heat conduction of copper is adopted as a heat transfer method from the lower surface 211 a of the evaporator housing 211 to the evaporator 112.

  This is the end of the description of the vaporization unit 210 in another form, and the description of the loop heat pipe 100 shown in FIG. 1 is continued.

  FIG. 8 is an enlarged view showing the evaporation section and the vicinity thereof in the loop heat pipe shown in FIG.

  In the loop heat pipe 100 of FIG. 1, as described above, the liquid-phase working fluid that has passed through the liquid pipe 140 is placed between the liquid inlet 111 a of the intake manifold 111 and the liquid pipe 140 in the evaporator 110. A reservoir tank 150 for temporarily storing is provided. Further, in the vicinity of the steam outlet 113 a of the exhaust manifold 113 in the evaporation unit 110, the steam pipe 130 is covered with a heat conduction block 170. The cooling unit 161 of the Peltier element 160 is in contact with the reservoir tank 150, and the heating unit 162 is in contact with the heat conduction block 170.

  FIG. 9 is a cross-sectional view schematically showing the internal structure of the reservoir tank 150 and the intake manifold 111.

  As described above, the inner wall surface of the intake manifold 111 is covered with the wick 111b including the inner wall surface of the liquid inlet 111a. The wick 111b of the intake manifold 111 is in contact with the wick 112c of the evaporator 112, and plays a role of guiding the liquid-phase first working fluid in the intake manifold 111 to the evaporator 112 by capillary action.

  The reservoir tank 150 is a rectangular parallelepiped box as shown in FIG. 9, and in this embodiment, the inner wall surface of the reservoir tank 150 is also the same wick as the wick 112c of the evaporator 112 and the wick 111b of the intake manifold 111. 151, and the wick 151 of the reservoir tank 150 is in contact with the wick 111 b of the intake manifold 111. The wick 151 of the reservoir tank 150 plays a role of guiding the liquid-phase first working fluid flowing in from the liquid pipe 140 to the intake manifold 111 by capillary action. Even if the liquid-phase first working fluid flowing in from the pipe 140 is small, the liquid-phase first working fluid is reliably guided to the intake manifold 111.

  With the configuration described above, the loop heat pipe 100 shown in FIG. 1 basically cools the CPU 510 that is a heating element by circulating the first working fluid while changing the phase.

  By the way, in this embodiment, the computer 500 is basically used in the posture shown in FIG. The loop heat pipe 100 is mounted in the computer 500 in a horizontal state in which the evaporator 110 and the condenser 120 are located at substantially the same height in the computer 500 placed in the posture shown in FIG. Yes. In general, when a loop type heat pipe is placed in a top heat or horizontal state where the position of the evaporator is higher than the position of the condenser, the liquid phase working fluid exists in the evaporator at the start of circulation of the working fluid. There is no guarantee that it will be dry, and the circulation of the working fluid may not start due to dryout. In the present embodiment, in order to eliminate such dry-out, the devices described below are elaborated in the vicinity of the liquid-phase working fluid inlet and the gas-phase working fluid outlet in the evaporation unit 110.

  As described with reference to FIG. 8, in this embodiment, the Peltier element 160 is interposed between the reservoir tank 150 connected to the liquid inlet 111a and the heat conduction block 170 covering the steam pipe 130 in the vicinity of the steam outlet 113a. Is arranged. The cooling unit 161 of the Peltier element 160 is in contact with the reservoir tank 150, and the heating unit 162 is in contact with the heat conduction block 170.

  Here, when dry-out occurs in the loop heat pipe 100, in many cases, the vapor phase working fluid is occupied from the inside of the evaporation unit 110 to the inside of the reservoir tank 150. At this time, the inside of the loop heat pipe 100 is set to the saturated vapor pressure of water as the first working fluid as described above. For this reason, when the temperature of the first working fluid in the vapor phase in the reservoir tank 150 becomes lower than the temperature of the working fluid in other portions such as the steam pipe 130, the phase change occurs in the reservoir tank 150. Wake up to generate a liquid first working fluid. In the present embodiment, when dry-out occurs, the cooling unit 161 of the Peltier element 160 cools the reservoir tank 150 to cool the first working fluid in the vapor phase in the reservoir tank 150, and the heating unit 162 heats the vapor pipe 130 through the heat conduction block 170, thereby heating the first working fluid in the vapor phase in the vapor pipe 130. Accordingly, a condition for causing a phase change in the reservoir tank 150 is created, and as a result, a liquid-phase first working fluid is generated in the reservoir tank 150. Although the liquid-phase first working fluid generated in this way is small, as described above, due to the capillary phenomenon in the wick 151 of the reservoir tank 150 and the capillary phenomenon in the wick 111b of the intake manifold 111 shown in FIG. It is reliably transmitted to the wick 112c in the evaporator 112 in the evaporator 110. Furthermore, the first working fluid in the liquid phase proceeds to the inside of the evaporator 112 due to the capillary action of the wick 112c itself of the evaporator 112, evaporates inside the evaporator 112, and this evaporation causes the first working fluid in the loop heat pipe 100. The circulation of one working fluid is started.

  In general, in a loop heat pipe placed in a top heat or horizontal state, even when the working fluid is circulated, when the heat generation in the heating element to be cooled continues to be low, the liquid phase The vapor pressure for sending the working fluid to the evaporating section is insufficient, and there is no liquid phase working fluid from the evaporating section, causing dryout and stopping the circulation. In the loop heat pipe 100 of the present embodiment, even when such a dry-out occurs during circulation and the circulation stops, the first phase of the vapor phase in the reservoir tank 150 by the Peltier element 160 as described above. A first working fluid in the liquid phase is generated in the reservoir tank 150 by cooling one working fluid and heating the first working fluid in the vapor phase in the steam pipe 130 via the heat conduction block 170. As a result, the dry-out is eliminated and the once stopped circulation is resumed.

  Such cooling or heating by the Peltier element 160 controls ON / OFF of the Peltier element 160 based on the temperatures detected by the first to fourth temperature sensors 181,..., 184 shown in FIG. This is performed by the control unit 190.

  Hereinafter, ON / OFF control of the Peltier element 160 performed by the control unit 190 will be described.

  FIG. 10 is a flowchart showing the flow of processing in ON / OFF control of the Peltier element performed by the control unit shown in FIG.

The processing shown in the flowchart of FIG. 10 is started when power is supplied to the computer 500 of FIG. 1 and power is supplied to the CPU 510 that is a heating element to be cooled of the loop heat pipe 100. When the processing is started, first, detection of the temperature T _cpu of the CPU 510, detection of the temperature T _tank of the reservoir tank 150, and heat conduction are performed by the first to fourth temperature sensors 181, ..., 184 shown in FIG. Detection of the temperature T _vp of the block 170 and detection of the temperature T _cond of the condenser 120 are started (step S101).

Then, the control unit 190 determines whether or not the temperature T _tank of the reservoir tank 150 and the temperature T _vp of the heat conduction block 170 satisfy the conditional expression T _tank <(T _vp −a1) (step S1). S102). Here, a1 is a specified temperature difference determined in advance as a lower limit value of the temperature difference between the temperature T _tank of the reservoir tank 150 and the temperature T _vp of the heat conduction block 170 when dryout has not occurred, This corresponds to an example of the first value in the basic form of the second loop heat pipe described above.

  In step S102, the above-mentioned conditional expression is not satisfied (No determination in step S102) means that dryout has occurred and the reservoir tank 150 and the steam pipe 130 covered with the heat conduction block 170 are It means that it is occupied by the first working fluid in the vapor phase of approximately the same temperature. Therefore, when the above conditional expression is not satisfied, the Peltier element 160 is turned on by the control unit 190, and the heat conduction block 170 is heated and the reservoir tank 150 is cooled (step S103). . After the Peltier element 160 is turned on, the process returns to step S102 and the above determination is repeated. When the above conditional expression is satisfied by the heating and cooling by the Peltier element 160 (Yes determination in step S102), the process proceeds to the next process (step S104).

In the present embodiment, the processing of steps S102 and S103, by detecting the temperature _{T vp} temperature _{T tank} and the heat conductive block 170 of the reservoir tank 150, the temperature difference between the reservoir tank 150 and the steam tube 130 Is detected indirectly, and when the temperature difference is smaller than the prescribed temperature difference a1, the temperature of the steam pipe 130 is increased and the temperature of the reservoir tank 150 is decreased.

In step S104, the control unit 190 determines whether or not the temperature T _tank of the reservoir tank 150 and the temperature T _cond of the condenser 120 satisfy the conditional expression T _tank <(T _cond −a2). . Here, a2 is a predetermined temperature that is predetermined as a lower limit value of the temperature difference between the temperature T _tank of the reservoir tank 150 and the temperature T _cond of the condenser 120 when the first working fluid starts to circulate sufficiently. It is a difference, and corresponds to an example of the second value in the application form of the second loop heat pipe described above.

  In step S104, the above-described conditional expression is not satisfied (No determination in step S104) means that the dry phase is being eliminated but the liquid-phase first working fluid in the reservoir tank 150 is small. , Meaning that the first working fluid has not yet circulated sufficiently. Therefore, in this case, the process returns to step S103 and the ON state of the Peltier element 160 is continued. Thereafter, the determination in step S102 and the determination in step S104 are repeated. When the first working fluid is sufficiently circulated and the conditional expression in step S104 is satisfied (Yes determination in step S104), the control unit 190 turns the Peltier element 160 to the OFF state (step S105). .

  The series of processes from step S101 to step S105 described above is a process for eliminating the dry-out at the start of the circulation of the first working fluid and starting the circulation normally.

Thus, even after the circulation of the first working fluid is normally started, the temperature T _cpu of the CPU 510 and the reservoir tank are detected by the first to fourth temperature sensors 181,..., 184 shown in FIG. The detection of the temperature T _tank 150, the detection of the temperature T _vp of the heat conduction block 170, and the detection of the temperature T _cond of the condenser 120 are subsequently performed (step S106).

Then, the control unit 190 determines whether or not the temperature T _cpu of the CPU 510 exceeds a predetermined upper limit temperature T _cpu (MAX) (step S107). This upper limit temperature T _cpu (MAX) corresponds to an example of an upper limit value in the above-described application mode.

When the temperature T _{cpu of the} CPU 510 does not exceed the upper limit temperature T _cpu (MAX) (No in step S107), it is confirmed that the circulation of the first working fluid is smooth and the CPU 510 is sufficiently cooled. This means that the Peltier element 160 is kept off (step S108).

On the other hand, when the temperature T _{cpu of} the CPU 510 exceeds the upper limit temperature T _cpu (MAX) (Yes in step S107), there is a possibility that the circulation of the first working fluid has stopped. Therefore, in order to confirm this, it is determined whether or not the temperature T _tank of the reservoir tank 150 and the temperature T _vp of the heat conduction block 170 satisfy the conditional expression T _vp <(T _tank + a3) ( Step S109). Here, a3 is a prescribed value that is determined in advance as a lower limit value of the temperature difference between the temperature T _tank of the reservoir tank 150 and the temperature T _vp of the heat conduction block 170 when the first working fluid is normally circulated. It is a temperature difference and corresponds to an example of the third value in the application form of the second loop heat pipe described above.

  That the above conditional expression is satisfied (Yes determination in step S109) means that dry out occurs and the reservoir tank 150 and the steam pipe 130 are in the vapor phase of the first working fluid having substantially the same temperature. Means that it is occupied by. Therefore, in this case, the Peltier element 160 is turned on again by the control unit 190, and the dryout is eliminated and the circulation is resumed (step S110).

After the Peltier element 160 is turned on, the determination in step S107 and the determination in step S109 are repeated. In the determination in step S107, it is determined that the temperature T _cpu of the CPU 510 does not exceed the upper limit temperature T _cpu (MAX). If this is done (No in step S107), it means that the circulation of the first working fluid has been resumed smoothly and the CPU 510 has been sufficiently cooled, and thus the process proceeds to step S108 and the Peltier element 160 is turned off. Is done.

  On the other hand, if the conditional expression in step S109 is not satisfied (No determination in step S109), an abnormal temperature increase has occurred in CPU 510 despite the smooth circulation of the first working fluid. In this case, the control unit 190 reduces the number of clocks in the CPU 510 or forcibly stops the CPU 510 (step S111). In this case, since the circulation of the first working fluid itself is smooth, the process proceeds to step S108, and the OFF state of the Peltier element 160 is continued.

  When the series of processes from step S106 to step S111 described above has stopped and the circulation has stopped after the start of the circulation of the first working fluid, the dryout is canceled, This is a process for resuming the circulation.

  As described above, according to the present embodiment, the loop heat pipe 100 is placed in a horizontal state in the computer 500, and therefore, dryout occurs at the start of the circulation of the first working fluid. Even after the cycle has begun, it can be started so as not to disturb the cycle. Furthermore, according to the present embodiment, when the dryout occurs after the start of circulation and the circulation is stopped, the dryout can be eliminated and the circulation can be resumed. In the present embodiment, the operation of the Peltier element, which consumes a relatively large amount of power, is observed at the start of circulation where the occurrence of dryout is assumed, and during the circulation, the CPU 510 sees an abnormal temperature rise. It is efficient because it is done when

  In the above, as an example of the loop heat pipe, the loop heat pipe 100 that is used in a horizontal state is illustrated. However, the loop heat pipe is not limited to this, for example, used in top heat. Or the like.

  In the above description, the computer 500 is illustrated as an example of the electronic device on which the loop heat pipe is mounted. However, the electronic device is not limited to the computer, and may be, for example, a home appliance.

  In the above description, the steam pipe 130 and the liquid pipe 140, which are copper pipes, are exemplified as the steam pipe and the liquid pipe in the loop heat pipe. However, the steam pipe and the liquid pipe are not limited thereto. For example, a metal tube other than copper may be used.

  In the above, water is exemplified as the working fluid, but the working fluid is not limited to this, and may be a fluid other than water, such as alcohol.

  In the above, an example in which both cooling of the reservoir tank and heating of the heat conduction block is performed by the Peltier element is shown, but the processing by the Peltier element is not limited to this, for example, only cooling of the reservoir tank is performed. It may be.

  In the above, Peltier elements are used for cooling and heating, but the method of cooling and heating is not limited to this. For example, the cooling is performed using a heat dissipation fan and the heating is performed by a heater. There may be.

  Hereinafter, the following additional notes will be disclosed with respect to various forms including the basic form and the application form described above.

(Appendix 1)
A steam pipe that connects the evaporator and the condenser, and a liquid pipe that connects the condenser and the evaporator are connected in a loop, and a loop heat pipe through which the working fluid passes through the liquid pipe. There,
Control means for controlling circulation of the working fluid;
The loop heat pipe according to claim 1, wherein the control means includes means for cooling the working fluid in the liquid pipe at the time of starting to start the circulation.

(Appendix 2)
An evaporator, a condenser, a vapor pipe connecting the evaporator and the condenser, and a liquid pipe connecting the condenser and the evaporator are connected in a loop, and a loop through which the working fluid passes. Type heat pipe,
First temperature difference detecting means for detecting a temperature difference between the steam pipe and the liquid pipe;
A loop type heat comprising: an adjusting means for raising the temperature of the steam pipe and lowering the temperature of the liquid pipe when the temperature difference is smaller than a predetermined first value. pipe.

(Appendix 3)
The loop heat pipe according to appendix 2, wherein the adjusting means is a mechanism including a Peltier element disposed between the steam pipe and the liquid pipe.

(Appendix 4)
The loop heat pipe according to appendix 3, wherein one surface of the Peltier element is in contact with the surface of the steam pipe, and the other surface of the Peltier element is in contact with the surface of the liquid pipe.

(Appendix 5)
The first temperature difference detecting means is means for indirectly detecting the temperature difference by detecting both the temperature of the steam pipe and the temperature of the liquid pipe and obtaining a difference between the two temperatures. The loop type heat pipe according to any one of supplementary notes 2 to 4, wherein the loop type heat pipe is provided.

(Appendix 6)
The evaporator is heated by a heating element that generates heat when supplied with power,
The adjusting means raises the temperature of the steam pipe and lowers the temperature of the liquid pipe when the temperature difference is smaller than the first value when power is supplied to the heating element. The loop heat pipe according to any one of appendices 2 to 5, characterized in that:

(Appendix 7)
The evaporator is heated by a heating element that generates heat when supplied with power,
The adjusting means raises the temperature of the steam pipe and lowers the temperature of the liquid pipe when the temperature difference is smaller than the first value when power is supplied to the heating element, While power is supplied to the heating element, the temperature of the steam pipe is raised and the temperature of the liquid pipe is lowered when the temperature difference is smaller than a predetermined third value. The loop heat pipe according to any one of supplementary notes 2 to 6, characterized by:

(Appendix 8)
A steam pipe that connects the evaporator and the condenser, and a liquid pipe that connects the condenser and the evaporator are connected in a loop, and a loop heat pipe through which the working fluid passes through the liquid pipe. An electronic device comprising:
The loop heat pipe is
Control means for controlling circulation of the working fluid;
The electronic device according to claim 1, wherein the control means includes means for cooling the working fluid in the liquid pipe at the time of starting to start the circulation.

It is a perspective view of a computer which is a concrete embodiment of electronic equipment. It is a perspective view which shows the structure of the evaporation part of the loop type heat pipe shown in FIG. It is sectional drawing which cut | disconnected the evaporation part shown in FIG. 2 to the axial direction of an evaporator. It is sectional drawing which cut | disconnected the evaporation part shown in FIG. 2 in the direction orthogonal to the axial direction of an evaporator. It is a perspective view which shows the structure of the evaporation part of another form. It is sectional drawing which cut | disconnected the evaporation part of another form shown in FIG. 5 in the axial direction of the evaporator. It is sectional drawing which cut | disconnected the evaporation part of another form in the direction orthogonal to the axial direction of an evaporator. It is an enlarged view which shows the evaporation part and its vicinity of the loop type heat pipe shown in FIG. 2 is a cross-sectional view schematically showing the internal structure of a reservoir tank 150 and an intake manifold 111. FIG. It is a flowchart which shows the flow of a process in ON / OFF control of the Peltier device performed by the control part shown in FIG. It is a schematic block diagram which shows an example of the conventional loop type heat pipe. It is a perspective view which shows the structure of the evaporation part of the loop type heat pipe shown in FIG.

Explanation of symbols

30 pipe 50 heating element 90 heating section 91 heater 92 power supply 93 switch 94 control device 95 filter 1, 2, 100 loop type heat pipe 10, 60, 110 evaporation section 111 intake manifold 111a liquid inlet 12, 111b wick 11, 112 evaporator 112a Copper pipe 13, 112b Steam passage 112c Wick 113 Exhaust manifold 113a Steam outlet 114 Evaporator container 114a Lower surface 114b Inner space 115 Heat insulating material 116 First working fluid 117 First working fluid of vaporized vapor phase 118 Second Working fluid 20, 40, 120 Condenser 41, 121 Radiation fin 70, 130 Steam pipe 80, 140 Liquid pipe 150 Reservoir tank 151 Wick 160 Peltier element 161 Cooling part 162 Heating part 170 Conductive block 181 a first temperature sensor 182 the second temperature sensor 183 the third temperature sensor 184 fourth temperature sensor 190 control unit 210 evaporator 211 evaporator container 211a underside 211b cavity 500 computer 510 CPU
520 HDD
530 Power supply unit 540 Blower fan

Claims (2)

A steam pipe that connects the evaporator and the condenser, and a liquid pipe that connects the condenser and the evaporator are connected in a loop, and a loop heat pipe through which the working fluid passes through the liquid pipe. There,
Control means for controlling circulation of the working fluid;
The loop heat pipe according to claim 1, wherein the control means includes means for cooling the working fluid in the liquid pipe at the time of starting to start the circulation. A steam pipe that connects the evaporator and the condenser, and a liquid pipe that connects the condenser and the evaporator are connected in a loop, and a loop heat pipe through which the working fluid passes through the liquid pipe. An electronic device comprising:
The loop heat pipe is
Control means for controlling circulation of the working fluid;
The electronic device according to claim 1, wherein the control means includes means for cooling the working fluid in the liquid pipe at the time of starting to start the circulation.

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