JP5664107B2 - Loop-type heat pipe and electronic device equipped with such loop-type heat pipe - Google Patents

Description

  The present invention relates to a loop heat pipe.

  Conventionally, heat pipes are used for cooling electronic devices and the like. A heat pipe is a heat transfer device that transports heat using a phase change of a working fluid sealed inside.

  In order to improve the cooling capacity of the electronic device, a loop heat pipe has been developed as a heat pipe having an increased heat transport amount and an increased heat transport distance.

  The loop heat pipe receives a heat from a heating element, evaporates the liquid-phase working fluid to change the phase to a gas-phase working fluid, and an evaporation section having a vapor channel for flowing the gas-phase working fluid, And a condensing part for condensing the working fluid of the phase by heat radiation. The loop heat pipe includes a vapor pipe that circulates the working fluid that has changed to a gas phase in the evaporation section to the condensation section, and a liquid pipe that circulates the working fluid that has changed to the liquid phase in the condensation section to the evaporation section. Yes. The loop heat pipe may have a liquid reservoir that is disposed between the liquid pipe and the evaporator and holds the working fluid supplied to the evaporator. The loop heat pipe has a loop structure in which an evaporator, a steam pipe, a condenser, a liquid pipe, and a liquid reservoir are connected in series, and a working fluid is sealed inside. Yes.

  In the loop heat pipe, for example, an amount of working fluid equal to the sum of the volume of the vapor flow path of the evaporation section, the volume of the condensation section, the volume of the vapor pipe, and the volume of the liquid pipe is enclosed. The volume of the liquid reservoir is designed to be equal to the sum of the volume of the steam channel, the volume of the condenser, and the volume of the steam pipe.

  This is because, in an ideal operating state of the loop heat pipe, the working fluid in the vapor flow path, the vapor pipe and the condensing part of the evaporator is all in the gas phase, and the working fluid in the evaporator wick and the liquid pipe are all liquid. This is because it is assumed to be a phase.

Jentung Ku, Operating charactaristics of loop heat pipes, NASA Goddard space flight center, in: 29th Inter. Conf. Environ. Sys. , July 12-15, 1999, Denver, Colorado K. Goncharov et al. , Loop heat pipe with general evaporators, TAIS Ltd. , In: 30th Inter. Conf. Environ. Sys. , July 10-13, 2000, Toulouse, France Vladimir G. Pastukhov, et al. , Low-noise cooling system for PC on the base of loop heat pipes, Applied Thermal Engineering 27 (2007) 894-901.

  When the loop heat pipe is not operating, part of the heat that flows from the heating element to the evaporation section is transferred to the liquid pipe section near the evaporation section, and the working fluid in the liquid pipe near the evaporation section changes to the gas phase. There is a case. In such a state, since the liquid-phase working fluid is not well supplied to the evaporation unit, the loop heat pipe may not be activated.

  In view of this, an object of the present specification is to provide a loop heat pipe that can be activated even when a gas-phase working fluid is present in the liquid pipe.

  In order to solve the above problems, according to one form of a loop heat pipe disclosed in the present specification, a wick that evaporates a liquid-phase working fluid and changes the phase to a gas-phase working fluid; An evaporating section having a vapor flow path for circulating a phase working fluid, a condensing section for condensing a gas phase working fluid to change into a liquid phase working fluid, and a working fluid changed to a gas phase in the evaporating section A steam pipe that circulates to the condensing part, a liquid pipe that circulates the working fluid that has changed to a liquid phase in the condensing part to the evaporating part, and a working fluid that is disposed between the liquid pipe and the evaporating part and is supplied to the evaporating part And a working fluid in an amount that impregnates at least the wick. The volume of the liquid reservoir is determined by the sum of the volume of the steam flow path, the volume of the steam pipe, and the volume of the condensing part. Is also big.

  According to one form of the loop heat pipe disclosed in the present specification described above, the operation can be started even when a gas-phase working fluid is present in the liquid pipe.

  The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the appended claims.

  Both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed.

It is a figure which shows 1st Embodiment of the loop type heat pipe disclosed to this specification. It is a figure which shows the time of starting of the loop type heat pipe by a prior art example. It is a figure which shows an example at the time of starting of the loop type heat pipe of FIG. It is a figure which shows the other example at the time of starting of the loop type heat pipe of FIG. It is a figure which shows the other example at the time of starting of the loop type heat pipe of FIG. It is a figure which shows the further another example at the time of starting of the loop type heat pipe of FIG. It is a figure which shows 2nd Embodiment of the loop type heat pipe disclosed to this specification.

  Hereinafter, a preferred first embodiment of a loop heat pipe disclosed in the present specification will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof.

  FIG. 1 is a diagram illustrating a first embodiment of a loop heat pipe disclosed in the present specification.

  The loop heat pipe 10 of the present embodiment includes an evaporation unit 11, a condensing unit 12, a steam pipe 13, and a liquid pipe 14. The evaporation unit 11 receives heat from a heating element such as a CPU and evaporates the liquid-phase working fluid 16 to change the phase to the gas-phase working fluid 16 and the vapor channel 11b through which the gas-phase working fluid 16 flows. Have The condensing unit 12 condenses the gas-phase working fluid 16 by heat radiation and changes the phase to the liquid-phase working fluid 16. The steam pipe 13 circulates the working fluid 16 that has been changed to a gas phase in the evaporator 11 to the condenser 12. The liquid pipe 14 circulates the working fluid 16 that has changed to a liquid phase in the condensing unit 12 to the evaporation unit 11. The loop heat pipe 10 can be used by being incorporated in an electronic device, for example.

  The loop heat pipe 10 includes a liquid reservoir 15 that is disposed between the liquid pipe 14 and the evaporator 11 and holds the working fluid 16 supplied to the evaporator 11.

  In the loop heat pipe 10, the evaporating unit 11 cools the heating element 30 by receiving heat of vaporization that causes the liquid-phase working fluid 16 to change into a gas phase from the heating element 30. The working fluid 16 that has changed to the gas phase is cooled by the condensing unit 12 and changes to the liquid phase.

  The working fluid is sealed in the loop-shaped flow path. The working fluid 16 is responsible for heat transfer in the loop heat pipe 10 while undergoing a phase change between the liquid phase and the gas phase. The working fluid 16 is enclosed in the loop heat pipe 10 at a saturated vapor pressure.

  As the working fluid 16, for example, water, alcohol, ammonia, or chlorofluorocarbon can be used.

  The evaporation unit 11 includes a flat plate type wick 11a, a groove 11c that is disposed below the wick 11a and forms a steam channel 11b, and a housing 11d that houses the wick 11a, the steam channel 11b, and the groove 11c. . The housing 11d is a rectangular parallelepiped hollow container. In FIG. 1, the housing 11d is shown partially broken.

  For example, a heating element 30 such as a CPU is thermally connected to the housing 11d via a thermal bonding material (not shown) such as thermal grease. The heat of the heating element 30 is transmitted to the wick 11a through the housing 11d or the groove 11c. The casing 11d is preferably formed using a metal having high thermal conductivity such as copper.

  The wick 11a is formed using a porous material and has a large number of pores. The pores of the wick 11a communicate with the vapor channel 11b side from the liquid reservoir 15 side. The wick 11a has a rectangular shape in plan view. The wick 11a is formed using, for example, a porous body obtained by sintering stainless steel or copper powder.

  The working fluid 16 is supplied from the liquid reservoir 15 to the wick 11a. The working fluid 16 soaks into the wick 11 a by capillary action, and the wick 11 a becomes wet with the working fluid 16. The force by which the working fluid 16 in the liquid reservoir 15 is drawn into the wick 11 a by the capillary phenomenon forms the driving force of the working fluid 16 in the loop heat pipe 10. The liquid-phase working fluid 16 immersed in the wick 11a is heated by the heat supplied from the heating element 30 and is evaporated (vaporized).

  The flat plate type wick 11a has high heat collection efficiency from the flat plate-like heating element 30 such as a CPU. Further, the flat plate type wick 11 a has high liquid absorption efficiency of the working fluid 16 from the liquid reservoir 15. Therefore, the flat wick 11a has a high heat exchange rate for changing the phase of the liquid-phase working fluid 16 to the gas phase.

  The space between the wick 11a and the inner surface of the housing 11d is partitioned by a plurality of grooves 11c in the direction in which the gas-phase working fluid 16 moves to form a vapor channel 11b. The working fluid 16 that has been changed to a gas phase by the wick 11a travels into the steam pipe 13 through the steam channel 11b.

  The vapor-phase working fluid 16 that has flowed through the steam pipe 13 moves into the condensing unit 12. In the condensing unit 12, the working fluid 16 dissipates heat and changes to the liquid phase again. The working fluid 16 changed to the liquid phase proceeds into the liquid pipe 14. The condensing unit 12 preferably has a heat radiating plate or the like to promote heat radiation from the working fluid 16. Further, the condensing unit 12 is preferably cooled by being blown by a fan or the like in order to further promote heat radiation from the working fluid 16.

  In the loop heat pipe 10, the steam pipe 13 and the liquid pipe 14 are preferably arranged so that the flow direction of the working fluid 16 flowing through the pipe intersects the vertical direction. That is, the loop path formed by the vapor pipe 13 and the liquid pipe 14, and the evaporation section 11 and the condensation section 12 is arranged so as to be orthogonal to the substantially vertical direction. Note that either the steam pipe 13 or the liquid pipe 14 may be arranged so that the flow direction of the working fluid 16 flowing through the pipe intersects the vertical direction.

  In the loop heat pipe 10, the evaporator 11, the steam pipe 13, the condenser 12, the liquid pipe 14, and the liquid reservoir 15 are connected in series to form a loop-shaped flow path.

  The liquid reservoir portion 15 is formed integrally with the evaporation portion 11 using the housing 11d. The liquid reservoir 15 is a portion above the wick 11a of the housing 11d. The liquid reservoir 15 has a rectangular parallelepiped space above the rectangular wick 11a in the housing 11d, and stores the liquid-phase working fluid 16 in this space. The liquid reservoir 15 temporarily accumulates the liquid-phase working fluid 16 that has flowed in from the liquid pipe 14, and stably supplies the liquid-phase working fluid 16 to the wick 11 a of the evaporator 11. Therefore, a state in which the liquid phase working fluid 16 is always filled in the pores of the wick 11a is maintained.

  The amount of the working fluid 16 flowing from the liquid pipe 14 into the liquid reservoir 15 is not always constant, and may pulsate or be intermittent. Therefore, in the loop heat pipe 10, the working fluid 16 flowing out from the liquid pipe 14 is temporarily accumulated in the liquid reservoir 15, and the working fluid 16 accumulated in the liquid reservoir 15 is supplied to the wick 11a.

  The lower limit of the volume of the liquid working fluid 16 enclosed in the loop heat pipe 10 is an amount that impregnates at least the entire wick so that the liquid working fluid 16 evaporates in the wick 11a.

  The upper limit of the volume of the liquid working fluid 16 enclosed in the loop heat pipe 10 is the volume of the vapor flow path 11b of the evaporation unit 11, the volume of the vapor pipe 13, the volume of the condensing part 12, and the liquid pipe 14. In addition to the sum of the volume of the liquid reservoir 15, a space is left in a part of the liquid reservoir 15, and the volume of the remaining liquid reservoir 15 is filled with the working fluid 16. At this time, the volume at which the portion of the liquid reservoir 15 is filled with the working fluid 16 can be, for example, 10%, 30%, or 50% of the volume of the liquid reservoir 15.

  In particular, the volume of the liquid working fluid 16 enclosed in the loop heat pipe 10 includes the volume of the vapor flow path 11b of the evaporation unit 11, the volume of the vapor pipe 13, the volume of the condensation unit 12, and the liquid pipe 14. Is preferably equal to the sum of This is because, in an ideal operating state of the loop heat pipe 10, the vapor flow path 11 b and the vapor pipe 13 of the evaporation unit 11 and the working liquid 16 in the condensation unit 12 are all in a gas phase, and the wick 11 a of the evaporation unit 11. This is because all the working fluid in the liquid pipe 14 is assumed to be in a liquid phase.

  However, in a state where the loop heat pipe 10 is not operating, part of the heat flowing from the heating element 30 to the evaporation unit 11 is transmitted to the portion of the liquid pipe 14 close to the evaporation unit 11 (so-called heat leak). In some cases, the working fluid 16 in the liquid pipe 14 close to the evaporation unit 11 changes to a gas phase. In such a state, the liquid heat working fluid 16 is not properly supplied to the evaporation unit 11, and thus the loop heat pipe 10 may not be activated.

Therefore, in the loop heat pipe 10, the volume V _r of the liquid reservoir 15 is equal to the volume V _g of the steam flow path 11 b so that the loop heat pipe 10 can be started even when the gas-phase working fluid 16 exists in the liquid pipe 14. It is larger than the sum of the volume V _v of the steam pipe 13 and the volume V _c of the condenser 12. In particular, the volume V _r of the liquid reservoir 15 is the sum of the volume V _g of the steam flow path 11b, the volume V _v of the steam pipe 13, the volume V _c of the condenser 12, and the volume V _l of the liquid pipe 14. Is preferably equal to

  Next, it will be described below with reference to the drawings that the loop heat pipe 10 can be started even when the gas-phase working fluid 16 is present in the liquid pipe 14.

  First, it will be described below that the loop heat pipe according to the conventional example cannot be started well when the gas-phase working fluid 16 exists in the liquid pipe 14.

  FIG. 2 is a diagram illustrating a startup time of a loop heat pipe according to a conventional example.

In the loop heat pipe 100 shown in FIG. 2, the volume V _b of the liquid reservoir 150 is the sum of the volume V _g of the steam channel 11 b, the volume V _v of the steam pipe 13, and the volume V _c of the condenser 12. Is equal to The volume of the working fluid 16 enclosed in the loop heat pipe 100 is the sum of the volume of the vapor flow path 11b of the evaporation unit 11, the volume of the vapor pipe 13, the volume of the condensation unit 12, and the volume of the liquid pipe 14. be equivalent to. The loop heat pipe 100 has the same structure as the loop heat pipe shown in FIG. 1 except that the volume of the liquid reservoir 150 is different.

In the loop heat pipe 100, the volume V _b of the liquid reservoir 150 is expressed by the following equation (1).

V _b = V _g + V _v + V _c (1)

  The loop heat pipe 100 is in a state before starting. That is, the circulation of the working fluid 16 in the loop has not yet started. The loop heat pipe 100 has a so-called heat leak, and a part of the heat flowing from the heating element 30 to the evaporation unit 11 is transmitted to the portion of the liquid pipe 14 close to the evaporation unit 11 and is close to the evaporation unit 11. The working fluid 16 in the liquid pipe 14 is changed to a gas phase. An interface between the liquid phase and the gas phase of the working fluid 16 is located in the liquid pipe 14. Similarly, an interface between the liquid phase and the gas phase of the working fluid 16 is located in the steam pipe 13. The liquid reservoir 150 and the vapor flow path 11b are filled with a gas-phase working fluid 16. The condensing unit 12 is filled with a liquid-phase working fluid 16. It is assumed that the working fluid 16 is impregnated in the pores of the wick 11a.

Loop heat pipe 10 is thermally in equilibrium, as expressed by the following equation (2), the pressure P _a of the working fluid 16 in the vapor phase in the liquid pipe 14, the vapor phase in the steam pipe 13 The pressure P _b of the working fluid 16 is balanced.

P _a = P _b (2)

Here, the pressure P _a of the working fluid 16 in the vapor phase in the liquid pipe 14 is expressed by the following equation (3).

P _a = n _a · R · T _a / V _a (3)

Here, n _a is the number of moles of the working fluid 16 in the vapor phase of the liquid pipe in the 14, R is the gas constant, T _a is the liquid pipe 14 and the liquid reservoir 150 in the temperature of the working fluid 16 in the vapor phase, V _a Is the sum of the volume of the gas-phase working fluid 16 in the liquid pipe 14 and the volume V _b of the liquid reservoir 150. Here, when the volume of the gas-phase working fluid 16 in the liquid pipe 14 is expressed as V _av0 , the volume V _a is expressed by the following equation (4).

V _a = V _b + V _av0 (4)

The pressure P _b of the vapor-phase working fluid 16 in the steam pipe 13 is expressed by the following equation (5).

P _b = n _b · R · T _b / V _b (5)

Here, n _b is the number of moles of steam pipe 13 and the working fluid 16 in the gas phase of the steam flow path 11b, R is the gas constant, T _b is the operation of the gas phase of the steam pipe 13 and steam flow path 11b fluids 16 the temperature, V _b is the sum of the volume V _g of the volume and the steam channel 11b of the working fluid 16 in the vapor phase in the steam pipe 13.

Thus, the loop heat pipe 100 is in thermal equilibrium state, the pressure P _a and the pressure P _b of the working fluid 16 in the vapor phase in the steam pipe 13 of the working fluid 16 in the vapor phase in the liquid pipe 14 Is balanced. Therefore, when the gas-phase working fluid 16 is present in the liquid pipe 14, the position of the interface between the liquid phase and the gas phase of the working fluid 16 in the liquid pipe 14 does not move in the loop heat pipe 100. Since the liquid-phase working fluid 16 does not advance toward the evaporation unit 11, the loop heat pipe 100 cannot be started up well.

  Next, it will be described below that the loop heat pipe 10 of the present embodiment can be started even when the gas-phase working fluid 16 is present in the liquid pipe 14.

  FIG. 3 is a diagram illustrating an example when the loop heat pipe of FIG. 1 is activated.

Volume V _r of the liquid reservoir portion 15 is larger than the sum of the volume V _c of the volume V _v and the condensing unit 12 of volume V _g and steam pipe 13 of the steam flow path 11b, a large part than this sum When the volume V _{the add} to be added to the volume, the volume V _r of the liquid reservoir portion 15 is expressed by the following equation (6).

_{V r = V g + V v} + V c + V add = V b + V add (6)

The loop heat pipe 10 shown in FIG. 3 is in a state where the volume V _b of the liquid reservoir 150 is increased to the volume V _r = V _b + V _add with respect to the loop heat pipe 100 in the state shown in FIG. Correspond.

The pressure P _c of the gas-phase working fluid 16 in the liquid pipe 14 is expressed by the following equation (7).

_{P c = n a · R ·} T a / V c (7)

Here, V _c is expressed by the following equation (8).

_Vc = _Vb + _Vadd + _Vav (8)

Here, V _av is the volume of the gas-phase working fluid 16 in the liquid pipe 14. In the loop heat pipe 10 shown in FIG. 3, V _av is equal to V _av0 .

On the other hand, since the value of the pressure P _b of the gas-phase working fluid 16 in the steam pipe 13 represented by the equation (5) does not change, P _c <P _{b in} the state of the loop heat pipe 10 shown in FIG. Become. Therefore, a force acts on the liquid-phase working fluid 16 so as to move toward the evaporation unit 11, so that the position of the interface between the liquid phase and the gas phase of the working fluid 16 in the liquid pipe 14 moves toward the evaporation unit 11. To do. Accordingly, the volume V _av of the gas-phase working fluid 16 in the liquid pipe 14 is reduced.

In the above description, the volume of the liquid reservoir is increased by the volume V _add with respect to the loop heat pipe 100 shown in FIG. 2 having a pressure relationship of P _a = P _{b, and} the loop type shown in FIG. It has been stated that when changing to a heat pipe, a pressure relationship of P _c <P _b can be obtained. However, if the volume V _r of the liquid reservoir 15 is equal to V _g + V _v + V _c + V _l , the gas phase working fluid 16 exists in the liquid pipe 14 in the loop heat pipe 10 shown in FIG. Even in this case, the pressure relationship of P _c <P _b is obtained similarly.

In the loop heat pipe 10 having a pressure relationship of P _c <P _b , the volume of the gas-phase working fluid 16 in the liquid pipe 14 is reduced, and the portion of the gas-phase working fluid 16 in the liquid pipe 14 is vaporized. Moving into the pipe 13, the volume of the gas-phase working fluid 16 in the steam pipe 13 increases. The transition of this state is shown as a change from FIG. 3 to FIG. 4 of the loop heat pipe 10.

At this time, since the liquid-phase working fluid 16 in the wick 11a impregnated with the working fluid evaporates, the number of moles of the gas-phase working fluid 16 in the steam tube 13 increases. The pressure _Pb is kept constant. The vapor phase working fluid 16 is contained in the pores of the wick 11a due to the evaporation of the liquid phase working fluid 16 in the wick 11a. Since it is sufficiently smaller than the volume V _{g of the} passage 11b and the volume V _v of the steam pipe 13, it can be ignored.

Further, since heat leak from the heating element 30 to the liquid pipe 14 continues in the liquid pipe 14, a phase change from the liquid-phase working fluid 16 to the gas phase continues to occur. On the other hand, in the liquid pipe 14, at the interface between the liquid phase and the gas phase of the working fluid 16, the gas phase working fluid 16 is cooled and changed to the liquid phase again. The same amount of the working fluid 16 in the gas phase as the amount of the fluid 16 changes into the liquid phase. Therefore, the number of moles n _a of the working fluid 16 in the vapor phase in the liquid pipe 14 is not affected at the interface position between the liquid and vapor phases of the working fluid 16.

Therefore, when the state of the loop heat pipe 10 changes from FIG. 3 to FIG. 4 due to the pressure relationship of P _c <P _b , the volume V _av of the gas-phase working fluid 16 decreases in the liquid pipe 14. Since the number of moles n _a is constant, the pressure P _{c of the} gas-phase working fluid 16 increases.

When the volume V _av of the gas-phase working fluid 16 in the liquid pipe 14 decreases, the volume V _av eventually becomes zero. At this time, the liquid pipe 14 is entirely filled with the liquid-phase working fluid 16. The state of the loop heat pipe 10 is shown in FIG. The pressure P _c in the liquid reservoir 15 at this time is expressed by the following equation (9) using equations (7) and (8).

_{P c = n a · R ·} T a / V c = n a · R · T a / (V b + V add) (9)

Here, the pressure P _b of the gas-phase working fluid 16 in the steam pipe 13 is expressed by the following equation (10) using equations (2) to (4).

_{P b = P a = n a} · R · T a / V a = n a · R · T a / (V b + V av0) (10)

Referring to equations (9) and (10), it can be _seen that if V _add > V _av0 , the pressure relationship of P _c <P _b is satisfied. When the state of the loop heat pipe 10 changes from FIG. 3 to FIG. 4, if V _add > V _av0 , the pressure relationship of P _c <P _b is satisfied and the gas-phase working fluid 16 As the volume V _av decreases, the number of moles n _a is constant, so the pressure P _{c of the} gas-phase working fluid 16 increases.

Here, V _av0 is the volume of the gas-phase working fluid 16 in the liquid pipe 14 in the loop heat pipe 100 of FIG. Accordingly, the volume V _r of the liquid reservoir 15 is _larger than the volume V _av0 of the gas-phase working fluid 16 in the liquid pipe 14 with respect to the volume V _b of the liquid reservoir 150 of the loop heat pipe 100 of FIG. It can be seen that the loop heat pipe can be started by increasing the volume V _av of the gas-phase working fluid 16 in the liquid pipe 14 to zero.

However, the volume V _av0 of the gas-phase working fluid 16 in the liquid pipe 14 in an equilibrium state in the loop heat pipe before starting is not constant. Therefore, considering the case where the volume V _av0 is maximized, as shown in FIG. 6, the entire liquid pipe 14 is filled with the gas phase working fluid 16.

In the loop heat pipe 10 shown in FIG. 6, the value of the volume V _av0 is equal to the volume V _{l of the} liquid pipe. Therefore, by making the added volume V _add larger than the volume V ₁ of the liquid pipe, regardless of the amount of the gas-phase working fluid 16 in the liquid pipe 14 in the loop heat pipe before starting, P _c <possible to obtain a relationship of P _b. Therefore, it is possible to reliably start the loop heat pipe 10 in which the gas-phase working fluid 16 exists in the liquid pipe.

Here, when the added volume V _add is made equal to the volume V _{l of the} liquid pipe, when the pressure relationship P _c = P _b is obtained, the liquid phase working fluid 16 in the liquid pipe 14 is stored in the liquid reservoir. The state reaches the part 15. Therefore, if the added volume V _add is at least equal to the volume V _l of the liquid pipe, the loop heat pipe 10 in which the gas-phase working fluid is present in the liquid pipe can be reliably started.

Depending on the degree of heat leak, if the volume V _av0 of the gas-phase working fluid 16 in the liquid pipe 14 in the loop heat pipe before activation is at most half the volume of the liquid pipe 14, it is added. The volume V _add to be used may be half the volume V _l of the liquid pipe 14. That is, the volume V _r of the liquid reservoir 15 is set to at least the volume V _g of the steam flow path 11b, the volume V _v of the steam pipe 13, the volume V _c of the condenser 12, and half the volume V _l of the liquid pipe 14. Just make it equal to the sum.

  According to the loop heat pipe 10 of the present embodiment described above, it can be started even when a gas-phase working fluid is present in the liquid pipe.

  Next, a loop heat pipe according to a second embodiment will be described below with reference to the drawings. For points that are not particularly described in the second embodiment, the description in detail regarding the first embodiment is applied as appropriate.

  FIG. 7 is a cross-sectional view showing a second embodiment of the loop heat pipe disclosed in this specification.

  In the loop heat pipe 20 of the present embodiment, the wick 11a is cylindrical. Similarly, the wick 11a is disposed in a cylindrical casing 11d. The liquid-phase working fluid 16 supplied from the liquid reservoir 15 flows into the wick 11a, and the working fluid 16 that has undergone a phase change in the wick 11a enters the housing 11d from the outer peripheral surface of the wick 11a. leak. The vapor-phase working fluid 16 flowing out of the wick 11a moves to the steam pipe 20 through the steam flow path 11b between the housing 11d and the wick 11a.

  As shown in FIG. 7, the liquid reservoir 15 is formed by increasing the diameter of the portion of the liquid pipe 16 on the evaporation unit 11 side. Thus, in the loop heat pipe 20, the liquid reservoir 15 is formed integrally with the liquid pipe 16.

  The volume of the liquid reservoir 15 is larger than the sum of the volume of the steam flow path 11b, the volume of the steam pipe 13, the volume of the condenser 12, and the volume of the liquid pipe 14.

  In the present invention, the loop heat pipe of each embodiment described above can be appropriately changed without departing from the gist of the present invention.

  The loop heat pipe of each embodiment described above may be incorporated in an electronic device having a heating element such as a CPU and used to cool the heating element. As described above, according to the electronic device provided with the loop heat pipe, since the loop heat pipe can be activated even when a gas-phase working fluid is present in the liquid pipe, the heating element is reliably cooled.

  Regarding the above-described embodiments, the following additional notes are disclosed.

(Appendix 1)
An evaporating section having a wick that evaporates the liquid-phase working fluid and changes the phase to a gas-phase working fluid;
A condensing part for condensing the gas-phase working fluid into a liquid-phase working fluid;
A steam pipe that circulates the working fluid changed to a gas phase in the evaporation section to the condensation section;
A liquid pipe that circulates the working fluid changed to a liquid phase in the condensing unit to the evaporation unit;
A liquid reservoir that is disposed between the liquid pipe and the evaporator and holds a working fluid supplied to the evaporator;
An amount of working fluid impregnated with at least the wick;
With
The volume of the liquid reservoir is a loop heat pipe that is larger than the sum of the volume of the steam channel, the volume of the steam pipe, and the volume of the condenser.

(Appendix 2)
The volume of the liquid reservoir is equal to the sum of the volume of the steam channel, the volume of the steam pipe, the volume of the condenser, and half the volume of the liquid pipe. pipe.

(Appendix 3)
The loop-type heat pipe according to appendix 2, wherein the volume of the liquid reservoir is equal to the sum of the volume of the steam channel, the volume of the steam pipe, the volume of the condenser, and the volume of the liquid pipe.

(Appendix 4)
The loop type heat pipe according to any one of appendices 1 to 3, wherein the steam pipe or the liquid pipe is arranged so that a flow direction of a working fluid flowing through the pipe intersects a vertical direction.

(Appendix 5)
In any one of appendixes 1-4, the working fluid having a volume equal to the sum of the volume of the vapor flow path, the volume of the condensing unit, the volume of the vapor pipe, and the volume of the liquid pipe is enclosed. The described loop heat pipe.

(Appendix 6)
The loop type heat pipe according to any one of appendices 1 to 5, wherein the wick has a flat plate shape.

(Appendix 7)
The loop heat pipe according to any one of appendices 1 to 6, wherein the wick before starting is impregnated with a working fluid.

(Appendix 8)
Electronic equipment provided with the loop heat pipe according to any one of appendices 1 to 7.

  All examples and conditional words mentioned herein are intended for educational purposes to help the reader deepen and understand the inventions and concepts contributed by the inventor. All examples and conditional words mentioned herein are to be construed without limitation to such specifically stated examples and conditions. Also, such exemplary mechanisms in the specification are not related to showing the superiority and inferiority of the present invention. While embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions or modifications can be made without departing from the spirit and scope of the invention.

DESCRIPTION OF SYMBOLS 10, 20 Loop type heat pipe 11 Evaporating part 11a Wick 11b Evaporating flow path 11c Groove 11d Case 12 Condensing part 13 Steam pipe 14 Liquid pipe 15 Liquid storage part 16 Working fluid 30 Heating element

Claims (5)

An evaporating section having a wick that evaporates the liquid-phase working fluid and changes the phase to a gas-phase working fluid;
A condensing part for condensing the gas-phase working fluid into a liquid-phase working fluid;
A steam pipe that circulates the working fluid changed to a gas phase in the evaporation section to the condensation section;
A liquid pipe that circulates the working fluid changed to a liquid phase in the condensing unit to the evaporation unit;
A liquid reservoir that is disposed between the liquid pipe and the evaporator and holds a working fluid supplied to the evaporator;
An amount of working fluid impregnated with at least the wick;
With
The volume of the liquid reservoir is a loop heat pipe equal to the sum of the volume of the steam flow path, the volume of the steam pipe, the volume of the condenser, and the volume of the liquid pipe. 2. The loop heat pipe according to claim 1, wherein the steam pipe or the liquid pipe is arranged so that a flow direction of a working fluid flowing through the pipe intersects a vertical direction. The loop type according to claim 1 or 2 , wherein a working fluid having a volume equal to a sum of a volume of the vapor channel, a volume of the condensing unit, a volume of the vapor pipe, and a volume of the liquid pipe is enclosed. heat pipe. The loop type heat pipe according to any one of claims 1 to 3 , wherein the wick has a flat plate shape. The electronic device provided with the loop type heat pipe as described in any one of Claims 1-4 .

Images