JP2013245875A - Cooling device and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a cooling device capable of easily removing steam bubbles, capable of providing stable cooling capability, and capable of suppressing deterioration of the cooling capability even when a calorific value of a heat source increases.SOLUTION: A cooling device includes: an evaporator 1 including a porous body 12, having a steam passage 10 and a liquid passage 11 separated by the porous body, and evaporating a working fluid of a liquid phase; a condenser 2 condensing the working fluid of a gaseous phase; a liquid storage tank 3 storing the working fluid of the liquid phase; a steam pipe 4 connecting a steam passage outlet of the evaporator and a condenser inlet; a liquid pipe 5 connecting a condenser outlet and a first inlet 3A of the liquid storage tank; a liquid supply pipe 6 connecting a liquid storage tank outlet and a liquid passage inlet of the evaporator; a liquid return pipe 7 connecting the liquid passage outlet of the evaporator and a second inlet 3B of the liquid storage tank; liquid transport means 8 interposed in the liquid supply pipe; a flow control valve 40 provided in the liquid return pipe; a temperature sensor 41 provided in the evaporator or the heat source; and a control part 42 controlling an opening of the flow control valve on the basis of information from the temperature sensor.

Description

  The present invention relates to a cooling device and an electronic device.

For example, as a cooling device for cooling a heating element such as an electronic component provided in an electronic device such as a computer, high cooling performance is obtained by utilizing latent heat of vaporization when a liquid-phase working fluid evaporates to become a gas-phase working fluid. There is a cooling device that uses a gas-liquid two-phase flow.
For example, an evaporator having a wick and a condenser are provided, the outlet of the evaporator and the inlet of the condenser are connected by a vapor pipe, the outlet of the condenser and the inlet of the evaporator are connected by a liquid pipe, There is a loop heat pipe (LHP) in which a working fluid is sealed.

In such a loop heat pipe, heat can be transported by circulating the working fluid by the capillary force of the wick without using a liquid transport pump or the like, for example. In addition, there is a liquid pipe provided with a liquid transport pump in order to reliably circulate the working fluid.
In addition, in the loop heat pipe, a flow rate adjusting valve is provided on the evaporation part side of a pump interposed in a pipe for supplying a liquid-phase working fluid from the tank to the evaporation part, and a temperature detector provided in the evaporation part is used. Some control the flow rate adjusting valve based on the temperature information.

JP 2002-303494 A JP 2005-321155 A JP 2004-190978 A JP-A-6-159959

By the way, as shown in FIG. 17, for example, the evaporator provided in the loop heat pipe as described above includes a case 101 thermally connected to the heating element 100, and a wick 102 in close contact with the inner wall surface of the case 101. Is provided.
Here, the wick 102 has a cylindrical shape, and the inside thereof is a cavity 103. The wick 102 is open on the inlet side (right side in FIG. 17) of the case 101 and closed on the outlet side (left side in FIG. 17) of the case 101. The cavity 103 inside the wick 102 communicates with a liquid pipe 104 connected to the inlet of the case 101, and serves as a liquid flow path through which a liquid-phase working fluid flows. A groove 105 is provided between the inner wall surface of the case 101 and the wick 102. The groove 105 communicates with a steam pipe 106 connected to the outlet of the case 101, and serves as a steam flow path through which a gas phase working fluid flows. In particular, the tip of the wick 102, that is, the portion of the wick 102 on the outlet side of the case 101 is closed, and the cavity 103 inside the wick 102 is dead-end. That is, the liquid flow path of the evaporator is dead end on the way.

In the loop heat pipe configured as described above, the heat of the heating element 100 may be transmitted to the liquid-phase working fluid via the wick 102 and heated to generate vapor bubbles in the liquid-phase working fluid. is there. As a result, dryout may occur and cooling performance may not be maintained.
In particular, the tip of the wick 102 is in contact with the steam channel, and the liquid-phase working fluid in the liquid channel near the tip of the wick 102 reaches a temperature approximately equal to the temperature of the gas-phase working fluid. Since it is heated, steam bubbles are easily generated. Further, for example, in the case of a thin flat plate evaporator suitable for efficiently cooling a flat plate heating element such as an electronic component having a large heat generation amount or a printed circuit board, the heat of the heating element 100 is in a liquid phase via the wick 102. Since it is easily transmitted to the working fluid and the temperature is likely to rise, vapor bubbles are likely to be generated in the liquid-phase working fluid. As a result, dryout is likely to occur and the cooling performance is not easily maintained.

In addition, even if a liquid transport pump is provided in the liquid pipe and the liquid-phase working fluid is sent to the evaporator by the liquid transport pump, the liquid flow of the evaporator is stopped halfway. Vapor bubbles generated in the fluid cannot be removed.
Further, in a loop heat pipe having a wick, when the amount of heat generated by the heating element (heat source) increases, the portion of the wick on the heating element side may dry, and cooling performance may deteriorate.

  Therefore, even when vapor bubbles are generated in the liquid-phase working fluid, the vapor bubbles can be easily removed, stable cooling performance is obtained, and the heat generation amount of the heat source is increased. However, it is desirable to realize a cooling device that can suppress a decrease in cooling performance.

  The cooling device includes a porous body and has a vapor channel and a liquid channel separated by the porous body, an evaporator that evaporates the liquid-phase working fluid, and a condensation that condenses the gas-phase working fluid. , A reservoir tank for storing a liquid-phase working fluid, a steam pipe connecting the outlet of the vapor flow path of the evaporator and the inlet of the condenser, the outlet of the condenser and the first inlet of the reservoir tank A liquid pipe connecting the outlet of the liquid reservoir tank and the inlet of the liquid flow path of the evaporator, an outlet of the liquid flow path of the evaporator and a second inlet of the liquid reservoir tank A liquid return pipe to be connected, a liquid transport means interposed in the liquid supply pipe, a flow rate adjusting valve provided in the liquid return pipe for adjusting the flow rate of the liquid-phase working fluid flowing in the liquid return pipe, and evaporation A temperature sensor provided in a heat source thermally connected to the evaporator or the evaporator, and a flow control valve based on information from the temperature sensor And a control unit for controlling the opening.

  The electronic device includes an electronic component provided on the wiring board and a cooling device for cooling the electronic component, the cooling device is configured as described above, and the electronic component is thermally connected to the evaporator. .

  Therefore, according to the present cooling device and electronic device, even when vapor bubbles are generated in the liquid-phase working fluid, the vapor bubbles can be easily removed, stable cooling performance can be obtained, and Even when the heat generation amount of the heat source is increased, there is an advantage that a decrease in cooling performance can be suppressed.

It is a schematic diagram which shows the structure of the cooling device concerning this embodiment. It is typical sectional drawing for demonstrating the effect by the cooling device concerning this embodiment. It is a typical perspective view which shows the structure of the liquid reservoir tank with which the cooling device concerning this embodiment is equipped, and a liquid transport pump. It is a typical perspective view which shows the specific structural example of the evaporator with which the cooling device concerning this embodiment is equipped, and the structural example of an electronic apparatus provided with the same. It is a typical perspective view which shows the specific structural example of the evaporator with which the cooling device concerning this embodiment is equipped. (A) is a schematic diagram for demonstrating the subject when the flow control valve is not provided in the cooling device concerning this embodiment, and (B) is the case where the flow control valve is provided in the cooling device concerning this embodiment. It is a schematic diagram for demonstrating an effect. It is a flowchart which shows the procedure of the opening degree control of the flow regulating valve by the control part with which the cooling device concerning this embodiment is equipped. It is a flowchart which shows the procedure of the opening control of the flow control valve by the control part with which the cooling device concerning this embodiment is equipped, and the output control of a liquid transport pump. It is a schematic diagram which shows the structure of the modification of the cooling device concerning this embodiment. It is a typical perspective view which shows the modification of the specific structural example of the evaporator with which the cooling device concerning this embodiment is provided, and the structural example of an electronic apparatus provided with the same. It is a typical perspective view which shows the modification of the specific structural example of the evaporator with which the cooling device concerning this embodiment is equipped. It is a typical perspective view which shows the modification of the liquid transport pump with which the cooling device concerning this embodiment is equipped. It is a typical perspective view which shows the other modification of the specific structural example of the evaporator with which the cooling device concerning this embodiment is equipped, and the structural example of an electronic apparatus provided with the same. It is a schematic diagram which shows the structure in the case of using the evaporator of the other modification of a specific structural example in the cooling device concerning this embodiment. (A), (B) is typical sectional drawing for demonstrating the effect of the electronic apparatus provided with the other modification of the specific structural example of the evaporator with which the cooling device concerning this embodiment is equipped. It is a typical perspective view which shows the modification of the specific structural example of the evaporator with which the cooling device concerning this embodiment is provided, and the structural example of an electronic apparatus provided with the same. It is typical sectional drawing for demonstrating the subject of the evaporator with which the conventional cooling device is equipped.

Hereinafter, a cooling device and an electronic device according to an embodiment of the present invention will be described with reference to FIGS.
The cooling device according to the present embodiment is a cooling device that cools a heating element such as an electronic component provided in an electronic device such as a computer (for example, a server or a personal computer). Note that the electronic device is also referred to as an electronic device. The electronic component is, for example, a CPU or an LSI chip.

Further, the present cooling device is a cooling device using a gas-liquid two-phase flow that realizes high cooling performance by using latent heat of evaporation when the liquid-phase working fluid evaporates to become a gas-phase working fluid.
Here, a cooling device including a thin flat plate evaporator suitable for efficiently cooling a flat heating element such as an electronic component having a large heat generation amount or a printed board (wiring board) will be described as an example. The thin plate evaporator is also referred to as a thin plate evaporator or a flat plate evaporator.

  As shown in FIG. 1, the cooling device includes an evaporator 1 that evaporates a liquid-phase working fluid, a condenser 2 that condenses a gas-phase working fluid, and a liquid storage tank 3 that stores the liquid-phase working fluid. A vapor pipe 4 through which a gas-phase working fluid flows, a liquid pipe 5 through which a liquid-phase working fluid flows, a liquid supply pipe 6 and a liquid return pipe 7, and a liquid transport pump 8. Since the liquid supply pipe 6 and the liquid return pipe 7 are liquid pipes through which a liquid-phase working fluid flows, they may be simply referred to as liquid pipes. In addition, the liquid transport pump 8 is used here, but the present invention is not limited to this, and any liquid transport means that can transport a liquid-phase working fluid may be used.

  The outlet of the steam flow path 10 of the evaporator 1 and the inlet of the condenser 2 are connected by a steam pipe 4. The outlet of the condenser 2 and the first inlet 3 </ b> A of the liquid reservoir tank 3 are connected by a liquid pipe 5. The outlet 3C of the liquid reservoir tank 3 and the inlet of the liquid flow path 11 of the evaporator 1 are connected by a liquid supply pipe 6. Further, the outlet of the liquid flow path 11 of the evaporator 1 and the second inlet 3 </ b> B of the liquid reservoir tank 3 are connected by a liquid return pipe 7. The liquid transport pump 8 is interposed in the liquid supply pipe 6. That is, the outlet 3C of the liquid reservoir tank 3 and the suction port 8A of the liquid transport pump 8 and the discharge port 8B of the liquid transport pump 8 and the inlet of the liquid flow path 11 of the evaporator 1 are connected by the liquid supply pipe 6. Yes.

  In the present embodiment, the evaporator 1 includes a wick 12, has a vapor channel 10 and a liquid channel 11 separated by the wick 12, and a heating element 9 (heat source) is thermally connected. Here, the vapor channel 10 is provided at a position close to the heating element 9 of the evaporator 1, and the liquid channel 11 is provided at a position far from the heating element 9 of the evaporator 1. This makes it difficult for the heat of the heating element 9 to be transmitted to the liquid-phase working fluid via the wick 12 so that vapor bubbles are less likely to be generated in the liquid-phase working fluid. The wick 12 is a porous body. Here, the porous body has a low thermal conductivity. Specifically, it is a resin porous body. The average pore size of the porous body is preferably about 10 μm or less (preferably about 6 μm or less). For example, the average pore diameter can be measured by a mercury injection method.

Here, as shown in FIG. 2, for example, the evaporator 1 includes a case 13 that is thermally connected to the heating element 9 and a wick 12 that is in close contact with the inner wall surface of the case 13.
Here, the wick 12 has a cylindrical shape, and the inside is a cavity 14. Further, the wick 12 is opened on the inlet side (right side in FIG. 2) and the outlet side (left side in FIG. 2) of the case 13. The cavity 14 inside the wick 12 communicates with the liquid pipe 6 connected to the inlet of the case 13 and the liquid pipe 7 connected to the outlet of the case 13, and the liquid flow path through which the liquid-phase working fluid flows. 11 is constituted.

Thus, the exit side portion of the wick 12, that is, the cavity 14 inside the wick 12 is not dead end, and communicates with the liquid pipe 7 connected to the exit of the case 13. That is, the liquid flow path 11 of the evaporator 1 is not dead end in the middle, and communicates with the liquid pipes 6 and 7 connected to the inlet side and the outlet side of the evaporator 1.
A groove 15 is provided between the inner wall surface of the case 13 and the wick 12. The groove 15 communicates with the steam pipe 4 connected to the outlet of the evaporator 1 and constitutes a steam flow path 10 through which a gas phase working fluid flows.

As described above, the liquid flow path 11 of the evaporator 1 communicates with the liquid pipes 6 and 7 connected to the inlet side and the outlet side of the evaporator 1. That is, the liquid flow path 11 of the evaporator 1 includes not only an inlet but also an outlet, penetrates from the inlet to the outlet, and is connected to the liquid pipes 6 and 7 on the inlet side and the outlet side of the evaporator 1. ing.
As shown in FIG. 1, the liquid pipes 6 and 7 connected to the inlet side and the outlet side of the evaporator 1 are connected to the liquid reservoir tank 3 and can circulate the liquid-phase working fluid. A path (loop) is formed.

Thereby, the liquid-phase working fluid flowing through the liquid flow path 11 of the evaporator 1 passes through the evaporator 1 and circulates without remaining in the evaporator 1.
For this reason, as shown in FIG. 2, the heat of the heating element 9 is transmitted through the wick 12, that is, due to heat leak, vapor bubbles are generated in the liquid-phase working fluid in the liquid flow path 11 inside the wick 12. Even if it occurs, the vapor bubbles can be easily removed from the liquid flow path 11 inside the wick 12 by flowing the liquid-phase working fluid. As a result, it is possible to prevent dryout, maintain cooling performance, and obtain stable cooling performance.

  In particular, the tip of the wick 12 is in contact with the vapor channel 10, and the liquid-phase working fluid in the liquid channel 11 near the tip of the wick 12 is approximately the same as the temperature of the gas-phase working fluid. Since it is heated to a temperature, vapor bubbles are likely to be generated. Further, in the case of a thin flat plate evaporator suitable for efficiently cooling a flat plate heating element such as an electronic component having a large heat generation amount or a printed circuit board, the heat of the heating element 9 is operated in a liquid phase via the wick 12. Vapor bubbles are likely to be generated because it is easily transmitted to the fluid and the temperature is likely to rise. In particular, when the evaporator 1 is thin and wide (long), the height of the liquid flow path 11 inside the wick 12 becomes low, so when a vapor bubble is generated, a liquid-phase working fluid enters under the vapor bubble. For example, dryout is likely to occur at the tip of the wick 12 or the like. In such a case, the vapor bubbles can be easily removed from the liquid flow path 11 inside the wick 12, thereby preventing the occurrence of dryout and obtaining stable cooling performance. It becomes possible.

In the cooling device configured as described above, a part of the liquid-phase working fluid supplied to the liquid flow path 11 of the evaporator 1 is supplied from the surface of the wick 12 facing the vapor flow path 10 of the evaporator 1. Exudes. That is, a part of the liquid-phase working fluid that has flowed from the inlet of the liquid flow path 11 of the evaporator 1 oozes out to the vapor flow path 10 side of the evaporator 1 through the wick 12.
The liquid-phase working fluid that oozes out from the surface of the wick 12 is in contact with a part of the wick 12 and a part of the case 13 of the evaporator 1. It is evaporated (vaporized) by the transmitted heat to become a gas phase working fluid.

As shown in FIG. 1, this gas phase working fluid flows into the condenser 2 through the vapor flow path 10 and the vapor pipe 4 of the evaporator 1, dissipates heat in the condenser 2, and is condensed by being cooled ( Liquefied) to become a liquid-phase working fluid.
This liquid-phase working fluid flows into the liquid storage tank 3 through the liquid pipe 5. That is, the liquid-phase working fluid flowing from the condenser 2 flows into the liquid reservoir tank 3 from the first inlet 3 </ b> A of the liquid reservoir tank 3.

The liquid-phase working fluid stored in the liquid reservoir tank 3 is supplied to the liquid flow path 11 of the evaporator 1 through the liquid supply pipe 6 by the liquid transport pump 8.
In this way, the working fluid recirculates in a circulation path constituted by the liquid reservoir tank 3, the liquid supply pipe 6, the evaporator 1, the vapor pipe 4, the condenser 2, and the liquid pipe 5.
On the other hand, another part of the liquid-phase working fluid supplied to the liquid flow path 11 of the evaporator 1 returns to the liquid storage tank 3 from the outlet of the liquid flow path 11 of the evaporator 1 through the liquid return pipe 7. That is, the other part of the liquid-phase working fluid that has flowed in from the inlet of the liquid flow path 11 of the evaporator 1 remains the liquid-phase working fluid, or a part of the liquid-phase working fluid flows from the wick 12. It becomes a mixed-phase working fluid that is vaporized by heat and becomes a working fluid in a gas phase, flows out from the outlet of the liquid flow path 11 of the evaporator 1, and returns to the liquid storage tank 3 through the liquid return pipe 7.

In this manner, the working fluid recirculates in a circulation path constituted by the liquid reservoir tank 3, the liquid supply pipe 6, the evaporator 1, and the liquid return pipe 7.
For this reason, by using this cooling device, the heat quantity of the heating element 9 can be efficiently transported by the latent heat of vaporization and sensible heat, so that extremely high cooling performance (heat radiation characteristics) can be realized.
That is, part of the heat transferred from the heating element 9 to the evaporator 1 is evaporated when the liquid-phase working fluid that has oozed into the vapor flow path 10 outside the wick 12 evaporates to become a gas-phase working fluid. It is stored in the vapor phase working fluid as latent heat (heat of vaporization), transported to the condenser 2 via the steam pipe 4, and radiated.

Part of the heat transferred from the heating element 9 to the evaporator 1 passes through the wick 12 and reaches the liquid flow path 11, and is stored as sensible heat in the liquid phase working fluid in the liquid flow path 11. Note that when the temperature of the liquid-phase working fluid becomes equal to or higher than the saturation temperature, a part of the liquid-phase working fluid changes into a gas-phase working fluid.
In the present cooling device, the working fluid flowing through the liquid flow path 11 is circulated by the liquid transport pump 8, so that the liquid-phase working fluid whose temperature has risen passes through the liquid return pipe 7 to the liquid It is sent to the reservoir tank 3. At this time, heat is radiated from, for example, the surface of the liquid return pipe 7. In this way, not only the vapor-phase working fluid but also the liquid-phase working fluid whose temperature has risen is sent out of the evaporator 1 without staying in the evaporator 1. That is, all the heat transmitted from the heating element 9 to the evaporator 1 is transported outside the evaporator 1 and is almost dissipated. For this reason, the temperature of the evaporator 1 can be kept low, and extremely high cooling performance can be realized.

As described above, the cooling device includes the evaporator 1 including the wick 12 and the condenser 2, and the outlet of the evaporator 1 and the inlet of the condenser 2 are connected by the vapor pipe 4. And an evaporator 1 are connected to each other by liquid pipes 5 and 6 and are loop type heat pipes in which a working fluid is sealed.
In this loop heat pipe, it is possible to circulate the working fluid by the capillary force of the wick 12 provided in the evaporator 1 to transport heat. That is, heat can be transported to the condenser 2 by the vapor pressure in the evaporator 1.

In this embodiment, the loop heat pipe configured as described above is further provided with a liquid reservoir tank 3, a liquid return pipe 7, and a liquid transport pump 8.
Here, one end of the liquid return pipe 7 is connected to the outlet of the liquid flow path 11 of the evaporator 1, and the other end of the liquid return pipe 7 is connected to the liquid reservoir tank 3. That is, the outlet of the liquid flow path 11 of the evaporator 1 and the second inlet 3 </ b> B of the liquid storage tank 3 are connected by the liquid return pipe 7. Further, the liquid reservoir tank 3 and the liquid transport pump 8 are interposed in the liquid pipes 5 and 6 that connect the outlet of the condenser 2 and the inlet of the evaporator 1. That is, a liquid pipe 5 and a liquid supply pipe 6 are provided as liquid pipes connecting the outlet of the condenser 2 and the inlet of the evaporator 1, and the outlet of the condenser 2 and the first inlet of the liquid reservoir tank 3 are provided. 3 </ b> A is connected by a liquid pipe 5, and an outlet 3 </ b> C of the liquid reservoir tank 3 and an inlet of the liquid flow path 11 of the evaporator 1 are connected by a liquid supply pipe 6. A liquid transport pump 8 is interposed in the liquid supply pipe 6.

  In this loop heat pipe, as a path through which the working fluid circulates, a first path (first loop) that circulates through the liquid reservoir tank 3, the liquid supply pipe 6, the evaporator 1, the steam pipe 4, the condenser 2, and the liquid pipe 5. ) And a second path (second loop) that circulates through the liquid reservoir tank 3, the liquid supply pipe 6, the evaporator 1, and the liquid return pipe 7. In this case, the working fluid flowing through the first path is circulated mainly by the capillary force of the wick 12, and the working fluid flowing through the second path is circulated mainly by the liquid transport pump 8.

By the way, when the distance between the evaporator as the heat receiving unit and the condenser as the heat radiating unit is long and the heat transport distance is long, or when the liquid channel is narrowed by reducing the thickness of the evaporator, for example, a microchannel, the circulation path Therefore, a large liquid transport pump (or a plurality of liquid transport pumps) is required.
On the other hand, in the present embodiment, as described above, the second path for circulating the liquid-phase working fluid by the power of the liquid transport pump 8 has a short distance. In addition, since this cooling device uses latent heat of vaporization, the amount (liquid amount) of the liquid-phase working fluid supplied to the evaporator 1 by the liquid transport pump 8 is also larger than that of a cooling device using single-phase sensible heat. Very few.

  In this way, it is only necessary to circulate a small amount of working fluid in a short circulation path, and since the pressure loss in the circulation path is small, a small liquid transport pump 8 (or a small number of liquid transport pumps 8) may be provided. That is, even a small liquid transport pump 8 can circulate a sufficient amount of working fluid, and a large liquid transport pump is not necessary (or it is not necessary to increase the number of liquid transport pumps).

  Further, in the case where the evaporator 1 is a thin and wide thin flat plate evaporator, it is difficult to evaporate the liquid-phase working fluid by uniformly immersing it in the wick 12 having a large area, and a part of the wick 12 is dried out. For example, the circulation of the working fluid becomes unstable. However, this can be prevented by providing the liquid transport pump 8. This makes it possible to obtain stable cooling performance. As a result, it is possible to efficiently cool, for example, a flat-type heating element such as an electronic component or a printed circuit board having a large calorific value, using a small liquid transport pump 8 and a thin flat plate evaporator. In other words, a flat plate-like heating element is achieved while making the evaporator 1 thinner (thinner / larger area) and the liquid transport pump 8 smaller (or fewer liquid transport pumps 8; smaller size / power saving). It becomes possible to cool efficiently. Note that reducing the size or the number of the liquid transport pumps 8 means reducing the volume of the liquid transport pump 8.

  Even if the distance between the evaporator 1 as the heat receiving part and the condenser 2 as the heat radiating part is long and the heat transport distance is long, a small liquid transport pump 8 may be provided. That is, even when the distance between the evaporator 1 and the condenser 2 is long and the heat transport distance is long, the distance is far away due to the capillary force of the wick 12 provided in the evaporator 1 and the vapor pressure in the evaporator 1. Since heat can be transported to the condenser 2 provided at the position, a small liquid transport pump 8 may be provided. Thereby, it is possible to realize a cooling device having a thin plate evaporator 1 with high efficiency and high performance.

By the way, in this embodiment, as shown in FIG. 3, the liquid reservoir tank 3 has a height sufficient to separate the liquid-phase working fluid and the gas-phase working fluid. That is, the liquid reservoir tank 3 has such a height that a space is formed above it in a state where the liquid-phase working fluid is stored.
In particular, the second inlet 3B of the reservoir tank 3 is preferably provided at a position farther from the outlet 3C of the reservoir tank 3 than the first inlet 3A. That is, the liquid reservoir tank 3 is provided at the outlet 3C to which the liquid supply pipe 6 is connected, the vicinity of the outlet 3C, the first inlet 3A to which the liquid pipe 5 is connected, and the position away from the outlet 3C. And a second inlet 3B to which the liquid return pipe 7 is connected.

  Here, the outlet 3C of the liquid reservoir tank 3 is provided below one wall surface 3X of the liquid reservoir tank 3, that is, below the wall surface on the downstream side in the circulation direction of the working fluid. The second inlet 3B of the reservoir tank 3 is provided on the other wall surface 3Y opposite to the one wall surface 3X of the reservoir tank 3, that is, on the upstream wall surface in the working fluid circulation direction. Further, the first inlet 3 </ b> A of the liquid reservoir tank 3 is provided on a wall surface 3 </ b> Z orthogonal to one and the other wall surfaces 3 </ b> X and 3 </ b> Y of the liquid reservoir tank 3. In the present embodiment, the liquid pipe 5 connected to the first inlet 3 </ b> A of the liquid reservoir tank 3 extends to the inside of the liquid reservoir tank 3, and the end thereof is located in the vicinity of the outlet 3 </ b> C of the liquid reservoir tank 3. It is like that.

In this way, the liquid-phase working fluid that flows through the liquid flow path 11 of the evaporator 1 without evaporating in the evaporator 1 and returns to the liquid reservoir tank 3 through the liquid return pipe 7 is as much as possible in the liquid reservoir tank 3. The liquid reservoir tank 3 is entered from a position far from the outlet 3C. Accordingly, the vapor bubbles can be reliably removed from the liquid-phase working fluid that may contain the vapor bubbles.
On the other hand, the liquid-phase working fluid condensed by the condenser 2 and returned to the liquid storage tank 3 through the liquid pipe 5 enters the liquid storage tank 3 from a position as close to the outlet 3C of the liquid storage tank 3 as possible. . As a result, the liquid-phase working fluid that is cooled by the condenser 2 and does not contain vapor bubbles preferentially exits from the outlet 3C of the reservoir tank 3 and is supplied to the evaporator 1 by the liquid transport pump 8. I have to.

Further, by installing the outlet 3C of the liquid reservoir tank 3 downward, even when the liquid-phase working fluid containing the vapor bubbles flows into the liquid reservoir tank 3, the vapor bubbles are moved upward in the tank 3. The working fluid flowing out from the outlet of the liquid storage tank 3 is made free from vapor bubbles.
The cooling device configured as described above is used to cool the electronic component 21 provided in the electronic device 20 such as a computer (see FIG. 4). In this case, the electronic device 20 includes an electronic component 21 and a cooling device 22 that cools the electronic component 21. The cooling device 22 is configured as described above (see FIG. 1), and the electronic component 21 is cooled. It is thermally connected to the evaporator 1 included in the device 22.

In this case, the electronic component 21 may be in contact with at least one of the front surface (upper side) and the rear surface (lower side) of the evaporator 1 included in the cooling device 22 via a wiring substrate 23 such as a printed circuit board (see FIG. 4), and may be in direct contact with at least one of the front surface and the back surface of the evaporator 1 included in the cooling device 22.
For example, a wiring board 23 such as a printed board on which the electronic component 21 is mounted may be provided on at least one of the front surface and the back surface of the evaporator 1 included in the cooling device 22 (see FIG. 4). The evaporator 1 included in the cooling device 22 may be provided on the surface of an electronic component provided on a wiring board such as a printed board. Moreover, you may provide the electronic component provided on wiring boards, such as a printed circuit board, so that an electronic component may contact | connect the surface of the evaporator 1 contained in the cooling device 22 directly. In addition, since the heat from the electronic component as the heating element is transmitted to the wiring board on which the electronic component is mounted, and the whole is a heating element, and the plate-like heating element, Alternatively, it is also called a flat plate type heating element.

Hereinafter, in order to efficiently cool the flat plate heating element 24, the flat plate evaporator 1 is provided, and the flat plate heating element 24 is provided on both the front and back surfaces of the flat plate evaporator 1 as an example. A description will be given with reference to FIGS.
As shown in FIG. 5, the evaporator 1 includes a case 13 (here, a metal case) having a liquid inlet 13A, a liquid outlet 13B, and a vapor outlet 13C, a wick 12 made of a resin porous body, a resin A liquid inlet side manifold 25 made of resin and a liquid outlet side manifold 26 made of resin are provided.

Here, the wick 12 is provided on each of the flat plate portion 12A, the front surface and the back surface of the flat plate portion 12A, extends in one direction and is arranged in parallel, and the flat plate portion 12A. And a plurality of through holes 12 </ b> C extending in other directions orthogonal to one direction and arranged in parallel.
Here, as shown in FIG. 4, the back surface of two resin porous plates 12AX having a plurality of convex portions 12B having a square cross section on the front surface side and a plurality of concave portions 12CX having a semicircular cross section on the back surface side. These are bonded together to form a wick 12 having a flat plate-like portion 12A, a convex portion 12B, and a through hole 12C.

When the wick 12 is housed in the case 13, the surfaces of the plurality of protrusions 12 </ b> B provided on the surface are in contact with the upper wall surface of the case 13, and each of the plurality of protrusions 12 </ b> B provided on the back surface is provided. Is in contact with the lower wall surface of the case 13.
As a result, a plurality of regions surrounded by the upper wall surface of the case 13, the flat plate-like portion 12 </ b> A of the wick 12, and the convex portion 12 </ b> B extend in one direction and become a plurality of through holes arranged in parallel. It becomes the steam flow path 10 through which the fluid flows. That is, grooves 15 are formed between the plurality of convex portions 12B provided on the surface of the wick 12. The upper portions of the plurality of grooves 15 are closed by the upper wall surface of the case 13, and the steam flow path 10 and Become.

  Similarly, the plurality of regions surrounded by the lower wall surface of the case 13, the flat plate portion 12A of the wick 12 and the projections 12B also extend in one direction and become a plurality of through holes arranged in parallel, and this is the operation of the gas phase It becomes the steam flow path 10 through which the fluid flows. That is, grooves 15 are formed between the plurality of convex portions 12B provided on the back surface of the wick 12. The upper portions of the plurality of grooves 15 are closed by the lower wall surface of the case 13, and the steam flow path 10 and Become.

Thus, in this embodiment, the evaporator 1 includes a plurality of vapor flow paths 10 on both sides of the flat plate portion 12A of the wick 12.
The plurality of through holes 12C provided in the flat plate-like portion 12A of the wick 12 serve as the liquid flow path 11 through which the liquid-phase working fluid flows. That is, the vapor flow path 10 provided on the front surface and the back surface of the flat portion 12A of the wick 12 and the liquid flow path 11 provided inside the flat portion 12A of the wick 12 are the flat shape of the wick 12. It is separated by a portion 12A. Then, due to the capillary force of the wick 12, the liquid-phase working fluid supplied to the liquid channel 11 passes through the holes of the wick 12 and oozes out to the vapor channel 10 side.

  Moreover, in this embodiment, the some liquid flow path 11 is extended in the other direction orthogonal to one direction, and is located in parallel. That is, in the present embodiment, the liquid flow path 11 and the vapor flow path 10 extend in directions orthogonal to each other. For this reason, as will be described later, the liquid outlet 13B and the steam outlet 13C can be provided on the mutually orthogonal wall surfaces of the evaporator 1. In other words, the liquid return pipe 7 and the steam pipe 4 can be connected to the mutually orthogonal wall surfaces of the evaporator 1. Thereby, with a simple configuration, the liquid-phase working fluid flowing in the liquid flow path 11 and the gas-phase working fluid flowing in the vapor flow path 10 are reliably separated, and the liquid-phase working fluid is transferred to the liquid return pipe 7. The gaseous working fluid can flow out to the vapor pipe 4.

  Thus, in the present embodiment, the evaporator 1 includes a vapor flow path layer including a plurality of vapor flow paths 10, a liquid flow path layer including a plurality of liquid flow paths 11, and a vapor flow including a plurality of vapor flow paths 10. It has a three-layer structure in which road layers are stacked. That is, the two outer layers are vapor flow path layers, and one inner layer sandwiched between these two vapor flow path layers is a liquid flow path layer. Thus, the evaporator 1 includes the steam channel 10 (first steam channel) provided on the upper side of the wick 12 and the steam channel 10 (second steam channel) provided on the lower side of the wick 12. And a liquid flow path 11 provided inside the wick 12. Here, in the case of the flat plate evaporator 1, the height of the outer steam channel layer is preferably about 1 mm or less, and the height of the inner liquid channel layer is preferably about 2 mm or less.

  Specifically, in this embodiment, the wick 12 is made of a porous body made of PTFE (polytetrafluoroethylene) resin having a porosity of about 40% and an average pore diameter of about 5 μm. In addition, the thickness of the wick 12, that is, the thickness from the surface of the convex portion 12B on the front surface to the surface of the convex portion 12B on the back surface is about 4 mm, and the dimension in the planar direction is about 110 mm × about 110 mm. . The cross section of the steam channel 10 is about 1 mm × about 1 mm, and the plurality of steam channels 10 are arranged in parallel at intervals (pitch) of about 2 mm. The diameter of the cross section of the liquid flow path 11 is about 1 mm, and the plurality of liquid flow paths 11 are arranged in parallel at an interval (pitch) of about 2 mm. Further, the thickness of the flat plate-like portion 12A of the wick 12 that separates the vapor channel 10 and the liquid channel 11 is about 0.5 mm at the thinnest portion.

  As shown in FIG. 5, the wick 12 configured in this way has a liquid inlet side manifold 25 attached to one side of the liquid flow path 11 and a liquid outlet side manifold 26 attached to the other side. In the case 13. That is, the case 13 includes a liquid inlet 13A on one wall surface, a liquid outlet 13B on a wall surface opposite to the one wall surface, and a steam outlet 13C on a wall surface orthogonal to the one wall surface. The wick 12 to which the liquid inlet side manifold 25 and the liquid outlet side manifold 26 are attached is housed in the case 13 so that the liquid flow path 11 extends from one wall surface of the case 13 to the opposite wall surface. Has been. Thereby, the steam flow path 10 of the wick 12 extends from the wall surface orthogonal to the one wall surface toward the opposite wall surface. The liquid inlet 13A of the case 13 is connected to the opening of the liquid inlet side manifold 25 and the liquid supply pipe 6. The liquid outlet 13B is connected to the opening of the liquid outlet side manifold 26 and the liquid return pipe 7. The steam pipe 4 is connected to the steam outlet 13C. As described above, the liquid supply pipe 6, the liquid inlet side manifold 25, the liquid flow path 11 of the wick 12, the liquid outlet side manifold 26 and the liquid return pipe 7 communicate with each other, and the vapor flow path 10 and the vapor pipe 4 of the wick 12 communicate with each other. Thus, the wick 12 and the like are housed in the case 13, and the liquid supply pipe 6 and the like are attached to the case 13.

  Specifically, in the present embodiment, the liquid inlet side manifold 25 and the liquid outlet side manifold 26 are resin manifolds made of, for example, MC nylon. The case 13 is a copper case having a wall thickness of about 0.3 mm. Here, the case 13 is provided with a copper container having an opening at the top and a copper lid for covering the upper opening, and after the wick 12 and the like are stored, the container and the cover are welded and sealed. Like to do.

Then, as shown in FIG. 4, a print in which a plurality of electronic components 21 (heat generating components) are mounted on both sides of the case 13 of the flat plate evaporator 1 configured as described above, that is, on the upper surface and the lower surface. A substrate 23, that is, a flat plate heating element 24 is provided. That is, the flat plate heating element 24 is thermally connected to both surfaces of the case 13 of the flat plate evaporator 1, that is, the upper surface and the lower surface.
Specifically, the upper surface of the case 13 of the flat plate evaporator 1 and the back surface of the flat plate heating element 24, that is, the back surface of the printed circuit board 23 on which the plurality of electronic components 21 are mounted are in close contact via thermal grease. Thus, heat from the flat plate heating element 24 is transmitted to the flat plate evaporator 1. Similarly, the lower surface of the case 13 of the flat plate evaporator 1 and the back surface of the flat plate heating element 24, that is, the back surface of the printed circuit board 23 on which the plurality of electronic components 21 are mounted are in close contact via thermal grease. The heat from the flat plate heating element 24 is transferred to the flat plate evaporator 1. Here, the amount of heat generated by the flat plate-type heating element 24 is about 150 W, for example. In this case, the plate-type evaporator 1 receives about 150 W of heat from each of the upper and lower surfaces, for a total of about 300 W.

  Incidentally, the printed circuit board 23 on which the plurality of electronic components 21 described above are mounted is provided in the electronic device 20. For this reason, the flat plate evaporator 1 thermally connected to the printed circuit board 23 on which the plurality of electronic components 21 are mounted is provided in the electronic device 20 in order to cool the electronic component 21 included in the electronic device 20. The cooling device 22 is included. Accordingly, the flat plate evaporator 1 is connected to the condenser 2, the liquid reservoir tank 3 and the liquid transport pump 8 included in the cooling device 22 configured as described above (see FIG. 1).

  Specifically, the condenser 2 is installed at a position about 300 mm away from the evaporator 1. The inlet of the condenser 2 is connected to the steam outlet 13 </ b> C of the flat plate evaporator 1 through the steam pipe 4. The condenser 2 is configured by bending a copper pipe having a length of about 300 mm, an outer diameter of about 6 mm, and an inner diameter of about 5 mm, for example, by bending it four times, and crimping an aluminum radiation fin (heat radiation member) (not shown) around the copper pipe. . Moreover, it shall be provided with the condensing apparatus provided with the condenser 2 and the ventilation fan (cooling means) which is not shown in figure, and air is ventilated with respect to a radiation fin, and it is trying to raise cooling capacity by forcibly cooling with air. Also good. The steam pipe 4 is a copper pipe having an outer diameter of about 6 mm and an inner diameter of about 5 mm. Note that other heat radiating members such as a heat radiating plate may be provided instead of the heat radiating fins. Moreover, you may make it cool by blowing air directly with respect to a pipe, without providing a heat radiating member. In addition, here, an air cooling method in which air is cooled by natural convection of air or air blowing is described as an example, but the present invention is not limited to this, and cooling is performed by water-cooling cooling means that cools with water. You may do it. That is, the condensing device may include a water-cooling type cooling means.

Further, the liquid reservoir tank 3 is installed adjacent to the flat plate evaporator 1 described above. The first inlet 3 </ b> A of the liquid reservoir tank 3 is connected to the outlet of the condenser 2 via the liquid pipe 5, and the second inlet 3 </ b> B of the liquid reservoir tank 3 is connected via the liquid return pipe 7. And connected to the liquid outlet 13B of the flat plate evaporator 1, and the outlet of the liquid storage tank 3 is connected to the liquid inlet of the flat plate evaporator 1 via the liquid supply pipe 6 and the liquid transport pump 8. 13A. The liquid storage tank 3 is a stainless steel tank having a wall thickness of about 0.3 mm, and has an outer size of about 50 mm × about 35 mm at the bottom and about 25 mm in height. The liquid pipe 5 is a copper pipe having an outer diameter of 4 mm and an inner diameter of 3 mm. The liquid supply pipe 6 is a stainless steel pipe having an outer diameter of about 4 mm and an inner diameter of about 3 mm, and the liquid return pipe 7 is a copper pipe having an outer diameter of about 4 mm and an inner diameter of about 3 mm. The liquid transport pump 8 is, for example, an electromagnetically driven piston type micro pump (Shinano Kenshi: PPLP-03060-001). Here, for example, when ethanol is used as the working fluid, the latent heat of vaporization is about 855 kJ / kg and the density is about 785 kg / m ³ , so that it is possible to transport about 671 J per cc. If the amount of heat transferred from the flat plate heating element 24 to the flat plate evaporator 1 is about 300 W (= 300 J / s), a flow rate of about 0.45 cc or more is required for 1 s. For this reason, the amount of liquid circulated by the liquid transport pump 8 was set to 0.5 cc / s (= 30 cc / min). The liquid transport pump 8 may be a piezo element driven diaphragm pump or a centrifugal turbo pump.

Therefore, according to the cooling device and the electronic device according to the present embodiment, even when vapor bubbles are generated in the liquid-phase working fluid, the vapor bubbles can be easily removed, and stable cooling performance is obtained. There is an advantage that
In particular, by using the cooling device including the thin flat plate evaporator 1 as in the above-described embodiment, it is possible to efficiently cool a flat type heating element such as an electronic component having a large calorific value or a printed board (wiring board). it can. Moreover, since heat transport can be performed using latent heat of vaporization and vapor pressure, a small liquid transport pump 8 may be provided. This makes it possible to improve the performance of electronic devices such as computers.

Actually, using the cooling device 22 (see FIGS. 4 and 5) described as a specific configuration example above, a printed circuit board 23 (a total calorific value of about 300 W) on which the electronic component 21 is actually operated is mounted. When the temperature of the electronic component 21 was measured after cooling, it was confirmed that any electronic component 21 maintained a temperature of about 80 ° C. or lower and could be cooled well.
Further, if the heat generation amount of the printed circuit board 23 on which the electronic component 21 is mounted is within a range of about 300 W at the maximum, the wick 12 in the evaporator 1 does not dry out and the electronic component 21 does not become abnormally hot, and is stable. It was confirmed that the obtained cooling performance was obtained.

  By the way, in the loop type heat pipe configured as described above, when the heat generation amount of the heating element 9 (including the flat plate heating element 24) increases, the supply of the liquid phase working fluid by the capillary force of the wick 12 catches up. First, as shown by a symbol X in FIG. 6A, the portion of the wick 12 on the side of the heating element 9 may be dried. That is, the liquid-phase working fluid may not come into contact with the heating element 9 in some cases. Thus, since the wick 12 which is a porous body is difficult to transmit heat, when the wick 12 is dried, the liquid-phase working fluid is hardly vaporized by the heat from the heating element 9, and the heating element 9 and the evaporator The temperature of 1 will rise and cooling performance will fall. In addition, the part by the side of the heat generating body 9 of the wick 12 is also called the part by the side of the steam flow path 10 of the wick 12, or the front-end | tip part of the wick 12. FIG.

  Therefore, in the present embodiment, as shown in FIG. 6B, the flow rate adjusting valve 40 is provided in the liquid return pipe 7, and when the amount of heat generated by the heating element 9 such as an electronic component increases, the flow rate adjusting valve 40 is provided. The flow rate of the liquid-phase working fluid flowing in the liquid return pipe 7 is reduced. As a result, the internal pressure of the liquid-phase working fluid in the liquid flow path 11 of the evaporator 1 is increased, and the liquid-phase working fluid is pushed out to the heating element 9 side of the wick 12. Can be prevented from drying, and the cooling performance can be prevented from deteriorating.

Specifically, in the present embodiment, as shown in FIG. 1, a flow rate adjusting valve 40, a temperature sensor 41, and a control unit 42 are further provided in the loop heat pipe configured as described above.
Here, the flow rate adjustment valve 40 is for adjusting the flow rate of the liquid-phase working fluid, and includes a valve portion 40A and a drive portion 40B that drives the valve portion 40A. The valve unit 40A is driven by the drive unit 40B based on a control signal from the control unit 42. The flow rate adjusting valve 40 is provided in the liquid return pipe 7 and functions to adjust the flow rate of the liquid-phase working fluid flowing through the liquid return pipe 7. Here, as the flow control valve 40, for example, a proportional control valve (solenoid valve) such as a direct acting / pilot type two-way proportional control valve positive flow (manufactured by Asco) may be used. The flow rate adjustment valve 40 is also referred to as a flow rate control valve, a control valve, a throttle valve, or a variable control type flow rate adjustment valve.

  Thus, since the flow rate adjusting valve 40 is provided in the liquid return pipe 7 on the downstream side of the evaporator 1, the load on the liquid transport pump 8 can be reduced, and the discharge of the liquid transport pump 8 can be reduced. The amount can be made constant, and the circulation of the liquid-phase working fluid can be stably maintained. On the other hand, when the flow regulating valve 40 is provided in the liquid supply pipe 6 on the upstream side of the evaporator 1 and the discharge amount of the liquid transport pump 8 is made constant, the discharge amount of the liquid transport pump 8 is the heat generation amount of the heating element 9. When the value is large, the required discharge amount is obtained. In this case, when the heat generation amount of the heating element 9 is small, the liquid-phase working fluid is blocked by the flow rate adjusting valve 40, so that the load on the liquid transport pump 8 becomes large.

  The temperature sensor 41 is provided in the evaporator 1 or a heating element (heat source) 9 that is thermally connected to the evaporator 1. For example, a thermocouple may be used as the temperature sensor 41. The temperature sensor 41 is connected to the control unit 42, and information from the temperature sensor 41 is sent to the control unit 42. Thereby, the temperature of the evaporator 1 or the heating element 9 can be detected by the temperature sensor 41 and the control unit 42. In this case, the temperature sensor 41 and the control unit 42 are referred to as temperature detection means. As the temperature sensor 41, a sensor that can detect the temperature of the evaporator 1 or the heating element 9 may be used. In this case, the temperature sensor 41 is also referred to as temperature detection means. In this case, the temperature information detected by the temperature sensor 41 is sent from the temperature sensor 41 to the control unit 42.

  Here, only one temperature sensor 41 or a plurality of temperature sensors 41 may be provided. For example, when the heating element 9 is a flat plate heating element 24 including a plurality of electronic components 21 (see, for example, FIG. 10), the temperature sensor 41 may be provided on the electronic component 21 that generates the largest amount of heat. Further, for example, when the heating element 9 is a flat plate heating element 24 including a plurality of electronic components 21 (see, for example, FIG. 10), the temperature sensors 41 may be provided in each of the plurality of electronic components 21. In this case, based on the highest temperature detected using each temperature sensor 41, the opening degree control of the flow rate adjustment valve 40, which will be described later, may be performed. That is, when any one of the temperatures detected by using each temperature sensor 41 exceeds a predetermined temperature, the opening degree control of the flow rate adjusting valve 40 described later may be performed.

  The control unit 42 has a function of controlling the opening degree of the flow rate adjustment valve 40 based on information from the temperature sensor 41. Here, the control unit 42 outputs a control signal to the drive unit 40B of the flow rate adjustment valve 40 based on the information from the temperature sensor 41, and the valve unit 40A is driven by the drive unit 40B accordingly, and the valve The valve opening (throttle amount) of the portion 40A is controlled. For example, the control unit 42 may perform feedback control of the opening degree of the flow rate adjustment valve 40 based on information from the temperature sensor 7. Here, the size of the flow path (opening) of the liquid return pipe 7 is controlled by controlling the opening degree of the flow rate adjusting valve 40 by the control unit 42. The control unit 42 is also referred to as a controller.

In this way, the opening of the flow rate adjustment valve 40 is controlled by the control unit 42 based on the information from the temperature sensor 41, so that the evaporator 1 is controlled according to the amount of heat generated by the heating element 9. It becomes possible to adjust the internal pressure of the liquid-phase working fluid in the liquid flow path 11.
In particular, when the heat generation amount of the heating element 9 increases, the temperature of the evaporator 1 or the heating element 9 detected using the temperature sensor 41 increases. In this case, the control unit 42 performs control to reduce the opening degree of the flow rate adjustment valve 40 based on the temperature of the evaporator 1 or the heating element 9, that is, the temperature detected using the temperature sensor 41. For example, when the temperature detected using the temperature sensor 41 exceeds a predetermined temperature, control is performed to reduce the opening degree of the flow rate adjustment valve 40. As a result, the flow rate of the liquid-phase working fluid flowing in the liquid return pipe 7 decreases, the internal pressure of the liquid-phase working fluid in the liquid flow path 11 of the evaporator 1 increases, and the liquid-phase working fluid becomes wick 12. As a result, the liquid-phase working fluid oozes out from the wick 12 to the steam flow path 10 side. Thereby, it can suppress that the part by the side of the heat generating body 9 of the wick 12 dries, and it becomes possible to suppress that cooling performance falls. When the heat generation amount of the heating element 9 is small and there is no possibility that the wick 12 will dry, it is preferable to fully open the flow rate adjustment valve 40 to reduce the load on the liquid transport pump 8.

  Actually, as a result of performing the opening degree control of the flow rate adjusting valve 40 described above, the opening degree of the flow rate adjusting valve 40 may be made too small. As a result, the amount of liquid that oozes out from the wick 12 toward the steam channel 10 exceeds the amount of evaporation, and the liquid-phase working fluid is mixed into the steam channel 10 and the steam pipe 4 to prevent the flow of the gas-phase working fluid, In the evaporator 1, the liquid-phase working fluid is difficult to vaporize, and the temperature of the evaporator 1 and the heating element 9 may increase. In this case, based on the temperature of the evaporator 1 or the heating element 9 detected using the temperature sensor 41, control for increasing the opening degree of the flow rate adjustment valve 40 may be performed.

In short, the opening degree control of the flow rate adjustment valve 40 may be performed so that the temperature of the evaporator 1 or the heating element 9 detected using the temperature sensor 41 is minimized.
Hereinafter, the opening degree control of the flow rate adjustment valve 40 by the control unit 42 will be specifically described with reference to the flowchart of FIG.
Here, a case where a plurality of temperature sensors 41 are provided will be described. The control unit 42 monitors the temperature of the evaporator 1 or the heating element 9, that is, information from each temperature sensor 41, and executes the processing shown in the flowchart of FIG. 7 at predetermined intervals. It shall be.

First, the control unit 42 detects the temperatures T1, T2, T3, T4... Of the evaporator 1 or the heating element 9 based on information from each temperature sensor 41 (step S10).
Next, the control unit 42 determines whether any of the temperatures T1, T2, T3, T4,... Exceeds a predetermined temperature (for example, 70 ° C.) (step S20).
As a result of this determination, if it is determined that none of the temperatures exceeds the predetermined temperature, the process proceeds to the NO route, and the current process is terminated.

On the other hand, if it is determined that one of the temperatures has exceeded the predetermined temperature, the process proceeds to the YES route, and the control unit 42 stores the temperature determined to have exceeded the predetermined temperature in association with the identification information of the temperature sensor 41. (Step S30).
Next, the control part 42 performs control which makes the opening degree of the flow regulating valve 40 small by predetermined amount (predetermined ratio; for example, 10%) (step S40). For example, the control unit 42 performs control to reduce the opening degree of the flow rate adjusting valve 40 by 10% with the throttle amount when fully opened as 0% and the throttle amount when fully closed as 100%. In the initial setting, it is assumed that the opening degree of the flow rate adjustment valve 40 is fully open (throttle amount 0%).

Next, the control unit 42 determines whether a predetermined time (for example, 10 seconds) has elapsed (step S50). As a result, if the predetermined time has not elapsed, the process proceeds to the NO route, and this determination is repeated.
If it is determined that the predetermined time has passed, the process proceeds to the YES route, and the information from the temperature sensor 41 used to detect the temperature determined to have exceeded the predetermined temperature in step S20 is taken in again. The temperature is detected again and the detected temperature is stored (step S60).

  In this way, it is detected how the temperature determined to have exceeded the predetermined temperature in step S20 has changed after a predetermined time has passed since the control for reducing the opening degree of the flow rate adjusting valve 40 is performed, and the temperature is detected. Remember. Here, the temperature before the opening degree control of the flow rate adjusting valve 40 is referred to as a temperature before the opening degree control, and the temperature after the predetermined time has elapsed after the opening degree control of the flow rate adjusting valve 40 is performed, after the opening degree control. It is called temperature.

Next, the control part 42 determines whether the temperature after opening control became lower than the temperature before opening control (step S70).
If it is determined that the temperature after the opening control has become lower than the temperature before the opening control, the process proceeds to the YES route, and the control unit 42 fully closes the opening of the flow rate adjustment valve 40 (the throttle amount is 100%). It is determined whether or not there is (step S80).

As a result of this determination, if it is determined that the opening degree of the flow rate adjustment valve 40 is not fully closed, the process proceeds to the NO route, returns to step S40, and the control unit 42 again sets the opening degree of the flow rate adjustment valve 40 to a predetermined amount. Control to make it as small as possible.
Thereafter, in step S70, it is determined that the temperature after opening control is not lower than the temperature before opening control, that is, the temperature after opening control is equal to or higher than the temperature before opening control, or step In S80, the processes of Steps S40 to S80 are repeated until it is determined that the opening degree of the flow rate adjustment valve 40 is fully closed.

In this way, when the temperature of the evaporator 1 or the heating element 9 exceeds a predetermined temperature (for example, 70 ° C.), control is performed to close the flow rate adjustment valve 40 by a predetermined ratio (for example, 10%). For example, the temperature is detected every 10 seconds), and the control for closing the flow rate adjustment valve 40 by a predetermined ratio (for example, 10%) is repeated as long as the temperature decreases.
Then, if it determines with the opening degree of the flow regulating valve 40 being fully closed by step S80, this process will be complete | finished.

  If it is determined in step S70 that the temperature after opening control is equal to or higher than the temperature before opening control, the process proceeds to the NO route, and the control unit 42 determines the temperature between the temperature after opening control and the temperature before opening control. It is determined whether the difference is within 1 ° C. (step S90). Here, whether or not the temperature of the evaporator 1 or the heating element 9 has become constant by determining whether the temperature difference (temperature change) between the temperature after opening control and the temperature before opening control is within 1 ° C. It is determined whether the temperature of the evaporator 1 or the heating element 9 is rising.

As a result of this determination, if it is determined that the temperature difference between the temperature after opening control and the temperature before opening control is within 1 ° C., it is determined that the temperature of the evaporator 1 or the heating element 9 has become constant, YES Proceed to the route and end the current process.
On the other hand, if it is determined that the temperature difference between the temperature after the opening control and the temperature before the opening control is not within 1 ° C., it is determined that the temperature of the evaporator 1 or the heating element 9 has increased, and the control proceeds to the NO route. The unit 42 performs control to increase the opening degree of the flow regulating valve 40 by a predetermined amount (predetermined ratio; for example, 10%) (step S100). For example, the control unit 42 performs control to increase the opening amount of the flow rate adjusting valve 40 by 10% with the throttle amount when fully opened being 0% and the throttle amount when fully closed being 100%. Here, when the temperature of the evaporator 1 or the heating element 9 rises, control is performed to return the opening degree of the flow rate adjustment valve 40 by one step. And this process is complete | finished.

By the way, here, when the amount of heat generated by the heating element 9 is increased, the opening degree of the flow rate adjusting valve 40 is controlled to suppress the decrease in cooling performance. However, the present invention is not limited to this. .
For example, when the heat generation amount of the heating element 9 increases, the output control of the liquid transport pump 8 may be controlled in addition to the opening degree control of the flow rate adjustment valve 40 to suppress the cooling performance. Since the discharge amount of the liquid transport pump 8 should be as constant as possible, the amount of heat generated by the heating element 9 is large, and when the opening control of the flow rate adjustment valve 40 is not sufficient, the liquid transport pump 8 is supplementarily supplemented. It is preferable to perform output control.

  In this case, the control unit 42 may have a function of controlling the output (for example, the rotational speed) of the liquid transport pump 8 based on information from the temperature sensor 41. Here, the control unit 42 may output a control signal to the liquid transport pump 8 based on information from the temperature sensor 41, and the output of the liquid transport pump 8 may be controlled accordingly. In particular, when the heat generation amount of the heating element 9 increases and the opening degree control of the flow rate adjusting valve 40 is not sufficient, the control unit 42 detects the temperature of the evaporator 1 or the heating element 9, that is, the temperature sensor 41. Based on the set temperature, control for increasing the output of the liquid transport pump 8 is performed. As a result, the flow rate of the liquid phase working fluid supplied to the liquid flow path 11 of the evaporator 1 increases, the internal pressure of the liquid phase working fluid in the liquid flow path 11 of the evaporator 1 increases, and the liquid phase operation The fluid is pushed out to the heating element 9 side of the wick 12. Thereby, it can suppress that the part by the side of the heat generating body 9 of the wick 12 dries, and it becomes possible to suppress that cooling performance falls. In addition, when the emitted-heat amount of the heat generating body 9 is small and there is no possibility that the wick 12 may dry, it is preferable to make the output of the liquid transport pump 8 constant.

Hereinafter, the opening degree control of the flow rate adjustment valve 40 and the output control of the liquid transport pump 8 by the control unit 42 will be specifically described with reference to the flowchart of FIG.
First, the control unit 42 performs processing similar to the processing in the flowchart of FIG. 7 described above in order to control the opening degree of the flow rate adjustment valve 40 (steps S10 to S100).
On the other hand, when the control unit 42 performs only the opening degree control of the flow rate adjusting valve 40 in order to perform the output control of the liquid transport pump 8 in addition to the opening degree control of the flow rate adjusting valve 40 (see FIG. 7), step S80. If it is determined that the opening degree of the flow rate adjustment valve 40 is fully closed, the processing is terminated, but the following processing for output control of the liquid transport pump 8 (steps S110 to S170) is performed.

  This is done for the following reason. That is, when it is determined in step S80 that the opening degree of the flow rate adjusting valve 40 is fully closed, the temperature of the evaporator 1 or the heating element 9 continues to decrease by repeatedly performing the opening degree control of the flow rate adjusting valve 40. Will be. For this reason, there is a possibility that the temperature of the evaporator 1 or the heating element 9 can be further lowered by increasing the internal pressure of the liquid-phase working fluid in the liquid flow path 11 of the evaporator 1. Therefore, if it is determined in step S80 that the opening of the flow rate adjustment valve 40 is fully closed, the internal pressure of the liquid-phase working fluid in the liquid flow path 11 of the evaporator 1 is further increased, and the evaporator 1 or the heating element 9 is increased. In order to lower the temperature of the liquid, the process for controlling the output of the liquid transport pump 8 (steps S110 to S170) is performed.

  Here, first, if it is determined in step S80 that the opening of the flow rate adjustment valve 40 is fully closed, the process proceeds to the YES route, and the control unit 42 sets the output (rotation speed) of the liquid transport pump 8 to a predetermined amount (predetermined ratio). For example, 5%) (Step S110). The maximum output of the liquid transport pump 8 is 100%, and the output of the liquid transport pump 8 is 80% in the initial setting.

Next, the control unit 42 determines whether a predetermined time (for example, 10 seconds) has elapsed (step S120). As a result, if the predetermined time has not elapsed, the process proceeds to the NO route, and this determination is repeated.
If it is determined that the predetermined time has passed, the process proceeds to the YES route, and the information from the temperature sensor 41 used to detect the temperature determined to have exceeded the predetermined temperature in step S20 is taken in again. The temperature is detected again, and the detected temperature is stored (step S130).

  In this way, it is detected how the temperature determined to have exceeded the predetermined temperature in step S20 has changed after a predetermined time has passed since the control for increasing the output of the liquid transport pump 8 is performed, and the temperature is determined. Remember. Here, the temperature before the output control of the liquid transport pump 8 is referred to as a temperature before the output control, and the temperature after the predetermined time has elapsed after the opening control of the flow rate adjustment valve 40 is referred to as the temperature after the output control.

Next, the control part 42 determines whether the temperature after output control became lower than the temperature before output control (step S140).
And when it determines with the temperature after output control having become lower than the temperature before output control, it progresses to YES route and the control part 42 determines whether the output of the liquid transport pump 8 is the maximum output (100%). (Step S150).

As a result of this determination, if it is determined that the output of the liquid transport pump 8 is not the maximum output, the process proceeds to the NO route, returns to step S110, and the control unit 42 increases the output of the liquid transport pump 8 by a predetermined amount again. Control to do.
Thereafter, in step S140, it is determined that the post-output control temperature is not lower than the pre-output control temperature, that is, the post-output control temperature is equal to or higher than the pre-output control temperature, or in step S150, the liquid Until it determines with the output of the transport pump 8 being the maximum output, the process of step S110-S150 is repeated.

  In this way, when the temperature of the evaporator 1 or the heating element 9 exceeds a predetermined temperature (for example, 70 ° C.), the opening degree of the flow rate adjustment valve 40 is controlled until the flow rate adjustment valve 40 is fully closed. Then, control is further performed to increase the output of the liquid transport pump 8 by a predetermined ratio (for example, 5%). Thereafter, the temperature is detected every predetermined time (for example, 10 seconds), and as long as the temperature decreases, the liquid transport pump 8 The control for increasing the output by a predetermined ratio (for example, 5%) is repeated.

Then, if it determines with the output of the liquid transport pump 8 being the maximum output in step S150, this process will be complete | finished.
If it is determined in step S140 that the post-output control temperature is equal to or higher than the pre-output control temperature, the process proceeds to the NO route, and the control unit 42 determines that the temperature difference between the post-output control temperature and the pre-output control temperature is 1 ° C. (Step S160). Here, by determining whether the temperature difference (temperature change) between the post-output control temperature and the pre-output control temperature is within 1 ° C., whether the temperature of the evaporator 1 or the heating element 9 has reached a constant state, or evaporation It is determined whether the temperature of the vessel 1 or the heating element 9 is rising.

As a result of this determination, if it is determined that the temperature difference between the post-output control temperature and the pre-output control temperature is within 1 ° C., it is determined that the temperature of the evaporator 1 or the heating element 9 has become a constant state and the YES route is entered. Proceed and end the current process.
On the other hand, when it is determined that the temperature difference between the post-output control temperature and the pre-output control temperature is not within 1 ° C., it is determined that the temperature of the evaporator 1 or the heating element 9 has increased, and the control unit 42 proceeds to the NO route. Performs control to reduce the output of the liquid transport pump 8 by a predetermined amount (predetermined ratio; for example, 5%) (step S170). Here, when the temperature of the evaporator 1 or the heating element 9 rises, control is performed to return the output of the liquid transport pump 8 by one step. And this process is complete | finished.

  Therefore, according to the cooling device and the electronic device according to the present embodiment, even when the amount of heat generated by the heating element 9 is increased, there is an advantage that a decrease in cooling performance can be suppressed. That is, according to the present cooling device and electronic device, even when vapor bubbles are generated in the liquid-phase working fluid, the vapor bubbles can be easily removed, stable cooling performance can be obtained, and Even when the heat generation amount of the heating element 9 is increased, there is an advantage that it is possible to suppress a decrease in cooling performance.

In addition, this invention is not limited to the structure described in embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.
For example, in order to further improve the performance of the cooling device in the above-described embodiment, a heat radiating member may be provided in the liquid return pipe 7 to actively dissipate heat. For example, a heat radiating fin or a heat radiating plate may be provided as part of the liquid return pipe 7 as a heat radiating member. Further, a cooling fan may be provided to forcibly cool the air by blowing air to the heat radiating member provided in the liquid return pipe 7. In addition, you may make it cool by blowing air directly with respect to the liquid return pipe | tube 7, without providing a heat radiating member. In addition, here, an air cooling method in which air is cooled by natural convection of air or air blowing is described as an example, but the present invention is not limited to this, and a cooling means of a water cooling type cooling means that cools with water. It may be cooled by. In this case, the cooling means for the liquid return pipe 7 is provided separately from the cooling means for the condenser.

  Further, as shown in FIG. 9, a part of the liquid return pipe 7 is provided inside a condensing device including the condenser 2 and a blower fan (cooling means) (not shown), thereby actively dissipating heat and cooling. You may make it do. For example, when a heat radiating member is provided in the liquid return pipe 7, a portion of the liquid return pipe 7 where the heat radiating member is provided may be provided inside the condensing device. In this case, as a cooling means such as a blower fan for cooling the liquid return pipe 7, the cooling means of the condensing device can also be used. Thereby, it becomes possible to cool the working fluid which flows through the liquid return pipe | tube 7 using the cooling capability in a condenser. For example, when the heat return member is not provided in the liquid return pipe 7, the liquid return pipe 7 is directly cooled by the cooling means of the condenser.

  Thereby, it is possible to positively remove the vapor bubbles contained in the liquid-phase working fluid flowing through the liquid return pipe 7. Further, for example, when the amount of heat flowing into the evaporator 1 is large, the temperature of the liquid-phase working fluid flowing through the wick 12 and flowing in the liquid flow path 11 is likely to rise. It is possible to improve the cooling performance by positively cooling the liquid-phase working fluid flowing through the.

In the above-described embodiment, the case where the flat plate heating elements 24 are provided on both surfaces of the flat plate evaporator 1 is described as an example. However, the present invention is not limited to this.
For example, as shown in FIG. 10, a flat plate heating element 24 may be provided on one side of the flat plate evaporator 1 so that the flat plate evaporator 1 and the flat plate heating element 24 are thermally connected.
In this case, the wick 12 is provided on the front surface side, extends in one direction, and is parallel to the plurality of convex portions 12B having a quadrangular cross section, and is provided on the back surface side in another direction orthogonal to the one direction. What is necessary is just to set it as the resin-made porous board provided with several recessed part 12CX of the cross-sectional semicircle shape extended and arranged in parallel.

When the wick 12 is stored in the case 13, the surface on the side where the plurality of convex portions 12B are formed is in contact with the upper wall surface of the case 13, and the surface on the side where the plurality of concave portions 12CX is formed. What is necessary is just to make it contact the lower wall surface of the case 13. FIG.
As a result, a plurality of regions surrounded by the upper wall surface of the case 13, the side surfaces of the convex portions 12B, and the bottom surfaces between the plurality of convex portions 12B extend in one direction and become a plurality of through holes arranged in parallel. It becomes the vapor | steam flow path 10 into which the working fluid of a phase flows. That is, grooves 15 are formed between the plurality of convex portions 12B provided on the surface of the wick 12. The upper portions of the plurality of grooves 15 are closed by the upper wall surface of the case 13, and the steam flow path 10 and Become. Further, a plurality of regions surrounded by the lower wall surface of the case 13 and the recess 12CX become a plurality of through holes 12C that extend in one direction and are arranged in parallel, and this becomes the liquid flow path 11 through which the liquid-phase working fluid flows. . In this case, the flat plate heating element 24 is thermally connected to the surface of the flat plate evaporator 1 on the side where the vapor flow path 10 is provided. That is, the electronic component 21 is thermally connected to the side of the flat plate evaporator 1 where the vapor flow path 10 is provided.

  In this case, the flat plate evaporator 1 includes the vapor flow path 10 on the upper side of the wick 12, that is, on the side in contact with the flat plate heating element 24, and on the lower side of the wick 12, that is, on the side in contact with the flat plate heating element 24. The liquid flow path 11 is provided on the opposite side. That is, the flat plate evaporator 1 has a two-layer structure in which a steam channel layer including a plurality of steam channels 10 and a liquid channel layer including a plurality of liquid channels 11 are stacked. As described above, the evaporator 1 includes the vapor channel 10 provided on one of the upper side and the lower side of the wick 12, and the liquid channel 11 provided on the other side of the upper side and the lower side of the wick 12. Is provided. Here, in the case of the flat plate evaporator 1, the height of the upper steam channel layer is preferably about 1 mm or less, and the height of the lower liquid channel layer is preferably about 1 mm or less. Such a flat plate evaporator 1 can be made thinner than the above-described embodiment.

Specifically, the thickness of the wick 12, that is, the thickness from the surface of the convex portion 12B on the front surface to the surface of the convex portion 12B on the rear surface is about 2 mm. The height of the cross section of the liquid channel 11 is about 0.5 mm. Other dimensions are the same as those in the specific configuration example of the above-described embodiment.
As shown in FIG. 11, the wick 12 configured as described above has a liquid inlet side manifold 25 attached to one side of the liquid flow path 11 and a liquid outlet side manifold 26 attached to the other side. In the case 13. That is, the case 13 includes a liquid inlet 13A on one wall surface, a liquid outlet 13B on a wall surface opposite to the one wall surface, and a steam outlet 13C on a wall surface orthogonal to the one wall surface. The wick 12 to which the liquid inlet side manifold 25 and the liquid outlet side manifold 26 are attached is housed in the case 13 so that the liquid flow path 11 extends from one wall surface of the case 13 to the opposite wall surface. Is done. Thereby, the steam flow path 10 of the wick 12 extends from the wall surface orthogonal to the one wall surface toward the opposite wall surface. Further, the opening of the liquid inlet side manifold 25 and the liquid supply pipe 6 are connected to the liquid inlet 13A of the case 13, and the opening of the liquid outlet side manifold 26 and the liquid return pipe 7 are connected to the liquid outlet 13B. The steam pipe 4 is connected to the steam outlet 13C. As described above, the liquid supply pipe 6, the liquid inlet side manifold 25, the liquid flow path 11 of the wick 12, the liquid outlet side manifold 26 and the liquid return pipe 7 communicate with each other, and the vapor flow path 10 and the vapor pipe 4 of the wick 12 communicate with each other. Thus, the wick 12 and the like are housed in the case 13, and the liquid supply pipe 6 and the like are attached to the case 13. Note that the specific configurations of the manifolds 25 and 26 and the material and dimensions of the case 13 are the same as those in the specific configuration example of the above-described embodiment.

  As shown in FIG. 10, the upper surface of the case 13 of the flat plate evaporator 1 and the back surface of the flat plate heating element 24, that is, the back surface of the printed circuit board 23 on which the plurality of electronic components 21 are mounted, The heat from the flat plate heating element 24 is transmitted to the flat plate evaporator 1. Here, the amount of heat generated by the flat plate-type heating element 24 is, for example, about 100 W. That is, the total amount of heat generated by the plurality of electronic components 21 included in the flat plate-type heating element 24 is about 100 W. For this reason, this amount of heat is input to the flat plate evaporator 1.

Further, the flat plate evaporator 1 is connected to the condenser 2, the liquid reservoir tank 3 and the liquid transport pump 8 included in the cooling device 22 as in the case of the above-described embodiment (see FIG. 1).
Specifically, the condenser 2 is configured such that a copper pipe having a length of about 300 mm, an outer diameter of about 4 mm, and an inner diameter of about 3 mm is bent, for example, four times, and an aluminum radiation fin (heat radiation member) (not shown) is caulked around the copper pipe. Has been. The steam pipe 4 is a copper pipe having an outer diameter of about 4 mm and an inner diameter of about 3 mm. The liquid pipe 5 is a copper pipe having an outer diameter of 3 mm and an inner diameter of 2 mm. The liquid supply pipe 6 is a stainless steel pipe having an outer diameter of about 3 mm and an inner diameter of about 2 mm, and the liquid return pipe 7 is a copper pipe having an outer diameter of about 3 mm and an inner diameter of about 2 mm. As shown in FIG. 12, for example, a piezo type micro pump (Takasago Electric SDMP320; standard flow rate 20 ml / min, maximum pump pressure 35 kPa, external dimensions 33 mm × 33 mm × 5.5 mm) was used as the liquid transport pump 8. Here, for example, when ethanol is used as the working fluid, the latent heat of vaporization is about 855 kJ / kg and the density is about 785 kg / m ³ , so that it is possible to transport about 671 J per cc. If the amount of heat transferred from the flat plate heating element 24 to the flat plate evaporator 1 is about 100 W (= 100 J / s), a flow rate of about 0.15 cc or more is required for 1 s. For this reason, the amount of liquid circulated by the liquid transport pump 8 was set to 0.166 cc / s (= 10 cc / min). The liquid transport pump 8 may be an electromagnetically driven piston type micro pump or a centrifugal turbo pump. Further, other specific configurations such as dimensions are the same as those in the specific configuration example of the above-described embodiment.

  Actually, by using such a cooling device 22, the printed circuit board 23 (a calorific value of about 100 W in total) on which the electronic component 21 in operation is mounted is cooled, and the temperature of the electronic component 21 is measured. It was confirmed that the electronic component 21 can also be cooled satisfactorily while maintaining a temperature of about 80 ° C. or lower. Further, if the heat generation amount of the printed circuit board 23 on which the electronic component 21 is mounted is in a range of about 100 W at the maximum, the wick 12 in the evaporator 1 does not dry out and the electronic component 21 does not become abnormally high in temperature. It was confirmed that the obtained cooling performance was obtained.

  For example, as shown in FIG. 13, a first flat plate evaporator 1X and a second flat plate evaporator 1Y are provided on both surfaces of the flat plate-type heating element 24, that is, on the upper surface and the lower surface, respectively. The second flat plate evaporators 1X and 1Y and the flat plate heating element 24 may be thermally connected. That is, as shown in FIG. 10, the flat plate heating element 24 is thermally connected to the flat plate evaporator 1, and the flat plate evaporator 1 is thermally connected to the flat plate heating element 24. You may do it.

  In this case, the first and second flat plate evaporators 1X and 1Y include the vapor flow path 10 on the side in contact with the flat plate heating element 24 and the liquid flow path 11 on the opposite side to the side in contact with the flat plate heating element 24. To prepare. That is, the first flat plate type evaporator 1X includes a vapor channel 10 (first vapor channel) provided on one side of the upper side and the lower side of the wick 12 (first porous body), and an upper side of the wick 12. And a liquid channel 11 (first liquid channel) provided on the other lower side. The second flat plate type evaporator 1Y includes a vapor channel 10 (second vapor channel) provided on one of the upper side and the lower side of the wick 12 (second porous body), and an upper side of the wick 12. And a liquid channel 11 (second liquid channel) provided on the other side of the lower side. And the side in which the vapor flow path 10 of the 1st flat plate type evaporator 1X is provided in the back surface side of the electronic component 21 is thermally connected, and the 2nd flat plate type evaporator 1Y of the electronic component 21 is provided in the surface side. The side on which the steam channel 10 is provided is thermally connected. The configuration and specific configuration example of the first and second flat plate evaporators 1X and 1Y are the same as those of the flat plate evaporator 1 shown in FIGS.

  Further, as shown in FIG. 13, the upper surface of the case 13 of the first flat plate evaporator 1X, that is, the surface of the case 13 on the steam flow path 10 side, and the lower surface of the flat plate heating element 24, that is, a plurality of electronic components. 21 is in close contact with the back surface of the printed circuit board 23 mounted with thermal grease. In addition, the lower surface of the case 13 of the second flat plate evaporator 1Y, that is, the surface of the case 13 on the vapor flow path 10 side, and the upper surface of the flat plate heating element 24, that is, a plurality of electrons mounted on the printed circuit board 23. The surface of the component 21 is in close contact with the thermal grease. Thereby, the heat from the flat plate heating element 24 is transmitted to the upper and lower first and second flat plate evaporators 1X and 1Y. Here, the amount of heat generated by the flat plate-type heating element 24 is about 200 W, for example. That is, the heat generation amount of the plurality of electronic components 21 included in the flat plate-type heating element 24 is about 200 W in total. Therefore, this amount of heat is input to the upper and lower first and second flat plate evaporators 1X and 1Y.

The first and second flat plate evaporators 1X and 1Y are connected to the condenser 2, the liquid reservoir tank 3 and the liquid transport pump 8 included in the cooling device 22, as shown in FIG.
Here, the steam pipe 4 connected to the condenser 2 is branched into two, and is connected to each of the first and second flat plate evaporators 1X and 1Y. That is, the steam pipe 4Y connected to the second flat plate evaporator 1Y is connected to the steam pipe 4X connecting the condenser 2 and the first flat plate evaporator 1X.

Further, a liquid return pipe 7 connected to the liquid storage tank 3 is branched into two, and is connected to each of the first and second flat plate evaporators 1X and 1Y. That is, the liquid return pipe 7Y connected to the second flat plate evaporator 1Y is connected to the liquid return pipe 7X connecting the liquid reservoir tank 3 and the first flat plate evaporator 1X.
Further, the liquid supply pipe 6 connected to the liquid reservoir tank 3 via the liquid transport pump 8 is branched into two and connected to the first and second flat plate evaporators 1X and 1Y, respectively. That is, the liquid supply pipe 6Y connected to the second flat plate evaporator 1Y is connected to the liquid supply pipe 6X that connects the liquid reservoir tank 3 and the first flat plate evaporator 1X via the liquid transport pump 8. Yes.

  Thus, here, the first flat plate evaporator 1X and the second flat plate evaporator 1Y are connected in parallel. That is, the liquid supply pipe 6Y, the second flat plate evaporator 1Y, and the steam are connected to a path including the liquid reservoir tank 3, the liquid supply pipe 6X, the first flat plate evaporator 1X, the vapor pipe 4X, the condenser 2 and the liquid pipe 5. A path composed of the tube 4Y is connected in parallel. In addition, a path including the liquid supply tank 6Y, the second flat plate evaporator 1Y, and the liquid return pipe 7Y is provided on the path including the liquid reservoir tank 3, the liquid supply pipe 6X, the first flat plate evaporator 1X, and the liquid return pipe 7X. Connected in parallel.

Further, here, the flow rate adjusting valve 40X is provided on the first flat plate evaporator 1X side from the portion of the liquid return pipe 7X to which the liquid return pipe 7Y is connected. The flow rate adjustment valve 40X includes a valve unit 40XA and a drive unit 40XB. Based on a control signal from the control unit 42, the valve unit 40XA is driven by the drive unit 40XB.
Further, a flow rate adjusting valve 40Y is provided in the liquid return pipe 7Y. The flow rate adjustment valve 40Y includes a valve unit 40YA and a drive unit 40YB. The valve unit 40YA is driven by the driving unit 40YB based on a control signal from the control unit 42.

The first flat plate evaporator 1X is provided with a temperature sensor 41X. The second flat plate evaporator 1Y is provided with a temperature sensor 41Y. The temperature sensors 41X and 41Y are respectively connected to the control unit 42, and information from each temperature sensor 41X and 41Y is sent to the control unit 42.
And the control part 42 controls the opening degree of the flow regulating valve 40X based on the information from the temperature sensor 41X. Moreover, the control part 42 controls the opening degree of the flow regulating valve 40Y based on the information from the temperature sensor 41Y. The specific opening control of the flow rate adjusting valve is the same as in the above-described embodiment. Moreover, you may make it also perform output control of the liquid transport pump 8 similarly to the case of the above-mentioned embodiment. In this case, a liquid transport pump is provided on each of the first flat plate evaporator 1X and the liquid supply pipe 6Y with respect to the portion of the liquid supply pipe 6X to which the liquid supply pipe 6Y is connected, and the output of each liquid transport pump Is preferably controlled based on information from each of the temperature sensors 41X and 41Y.

However, the present invention is not limited to this. For example, one flow rate adjustment valve 40 is provided on the liquid reservoir tank 3 side of the liquid return pipe 7X to which the liquid return pipe 7Y is connected. One or a plurality of temperature sensors 41 may be provided in any of 1X, the second flat plate evaporator 1Y, and the flat plate heating element (heat source) 24.
Moreover, it is not restricted to this, You may connect the 1st flat plate type evaporator 1X and the 2nd flat plate type evaporator 1Y in series. That is, instead of the liquid supply pipe 6Y, the liquid return pipe 7X connected to the outlet of the liquid flow path 11 of the first flat plate evaporator 1X is connected to the inlet of the liquid flow path 11 of the second flat plate evaporator 1Y. In addition, instead of the liquid return pipe 7X, the liquid return pipe 7Y connected to the outlet of the liquid flow path 11 of the second flat plate evaporator 1Y may be connected to the liquid reservoir tank 3. In this case, the steam pipes 4 (4X, 4Y) connected to the condenser 2 are connected to the first and second flat plate evaporators 1X, 1Y, respectively. Further, a liquid supply pipe 6 (6X) connected to the liquid reservoir tank 3 via the liquid transport pump 8 is connected to the inlet of the liquid flow path 11 of the first flat plate evaporator 1X. A liquid supply pipe 6 (6Y) connected to the inlet of the liquid flow path 11 of the second flat plate evaporator 1Y is connected to the outlet of the liquid flow path 11 of the first flat plate evaporator 1X. Further, a liquid return pipe 7 (7Y) connected to the outlet of the liquid flow path 11 of the second flat plate type evaporator 1Y is connected to the liquid reservoir tank 3. As a result, the liquid-phase working fluid is supplied from the liquid storage tank 3 through the liquid supply pipe 6X to the first flat plate evaporator 1X, and then through the liquid return pipe 7X as the liquid supply pipe, to the second flat plate type evaporation. The liquid is supplied to the container 1Y and returned to the liquid storage tank 3 through the liquid return pipe 7Y. In this case, a flow rate adjustment valve 40 is provided in the liquid return pipe 7Y, and one or more temperature sensors are provided in any of the first flat plate evaporator 1X, the second flat plate evaporator 1Y, and the flat plate heating element (heat source) 24. 41 may be provided.

The liquid transport pump 8 is, for example, an electromagnetically driven piston type micro pump (Shinano Kenshi: PPLP-03060-001) (see FIG. 3). Here, for example, when ethanol is used as the working fluid, the latent heat of vaporization is about 855 kJ / kg and the density is about 785 kg / m ³ , so that it is possible to transport about 671 J per cc. If the amount of heat transferred from the flat plate heating element 24 to the first and second flat plate evaporators 1X and 1Y is about 200 W (= 200 J / s), a flow rate of about 0.3 cc or more is required for 1 s. For this reason, the amount of liquid circulated by the liquid transport pump 8 was set to 0.333 cc / s (= 20 cc / min). The liquid transport pump 8 may be a piezo element driven diaphragm pump or a centrifugal turbo pump.

The specific configuration such as other dimensions is the same as that in the case where the flat plate evaporator 1 shown in FIGS. 10 and 11 is used.
In FIG. 14, a part of the liquid return pipe 7 is provided inside a condenser having the condenser 2 and a blower fan (cooling means) (not shown) so as to actively dissipate and cool it. However, the present invention is not limited to this, and for example, it may be configured similarly to that of the above-described embodiment (see FIG. 1).

  Actually, by using such a cooling device 22, the printed circuit board 23 (heat generation amount of about 200 W in total) on which the electronic component 21 in operation is mounted is cooled, and the temperature of the electronic component 21 is measured. It was confirmed that the electronic component 21 can also be cooled satisfactorily while maintaining a temperature of about 80 ° C. or lower. Further, if the heat generation amount of the printed circuit board 23 on which the electronic component 21 is mounted is in a range of about 200 W at the maximum, the wick 12 in the evaporators 1X and 1Y does not dry out and the electronic component 21 does not become abnormally hot. It was confirmed that stable cooling performance was obtained.

In particular, the first and second flat plate evaporators 1X and 1Y as described above can be made thinner than the above-described embodiment, and can be provided above and below the heating element 24. For this reason, it becomes possible to cool efficiently the heat generating body 24 with large heat_generation | fever like the 3D stacked package for implement | achieving high-density mounting, for example.
For example, as shown in FIGS. 15A and 15B, the 3D stacked package 30 includes a three-dimensional stacked package (LSI having a structure in which a plurality of semiconductor chips 31 and 31X (LSI chips) are stacked three-dimensionally. Package). Therefore, as shown in FIG. 15A, even if the 3D stacked package 30 is mounted on the printed circuit board (wiring board) 23 and the flat plate evaporator 1 of the above-described embodiment is provided thereon, It is difficult to sufficiently dissipate the heat generated by the semiconductor chip 31X located on the lower layer side, that is, on the printed board 23 side. Therefore, as shown in FIG. 15B, by providing the second flat plate type evaporator 1Y on the front surface side of the 3D stacked package 30 and providing the first flat plate type evaporator 1X on the back surface side of the printed circuit board 23, The heat generated by each of the semiconductor chips 31 and 31X included in the 3D stacked package 30 can be efficiently radiated. In this case, as described above, by using the thinned first and second flat plate evaporators 1X and 1Y, the mounting height can be reduced as compared with the structure shown in FIG. The heat generated by the semiconductor chips 31 and 31X included in the 3D stacked package 30 can be efficiently dissipated without increasing the height.

In the above-described embodiment, the vapor channel 10 and the liquid channel 11 of the evaporator 1 are provided so as to extend in directions orthogonal to each other. However, the present invention is not limited to this. For example, as shown in FIG. 16, the vapor channel 10 and the liquid channel 11 of the evaporator 1 may be provided so as to extend in the same direction.
Hereinafter, additional notes will be disclosed regarding the above-described embodiments and modifications.

(Appendix 1)
An evaporator having a porous body, having a vapor channel and a liquid channel separated by the porous body, and evaporating a liquid-phase working fluid;
A condenser that condenses the gas-phase working fluid;
A reservoir tank for storing the liquid-phase working fluid;
A steam pipe connecting the outlet of the steam flow path of the evaporator and the inlet of the condenser;
A liquid pipe connecting the outlet of the condenser and the first inlet of the reservoir tank;
A liquid supply pipe connecting an outlet of the liquid reservoir tank and an inlet of the liquid flow path of the evaporator;
A liquid return pipe connecting an outlet of the liquid flow path of the evaporator and a second inlet of the liquid storage tank;
Liquid transport means interposed in the liquid supply pipe;
A flow rate adjusting valve provided in the liquid return pipe for adjusting the flow rate of the liquid-phase working fluid flowing in the liquid return pipe;
A temperature sensor provided in the evaporator or a heat source thermally connected to the evaporator;
And a controller that controls the opening of the flow rate adjustment valve based on information from the temperature sensor.

(Appendix 2)
The cooling device according to appendix 1, wherein the control unit controls the output of the liquid transporting unit based on information from the temperature sensor.
(Appendix 3)
The cooling device according to appendix 1 or 2, wherein the porous body is a resin porous body.

(Appendix 4)
The cooling device according to any one of appendices 1 to 3, wherein a heat radiating member is provided in the liquid return pipe.
(Appendix 5)
A condenser comprising the condenser and cooling means;
The cooling device according to any one of appendices 1 to 4, wherein a part of the liquid return pipe is provided inside the condensing device.

(Appendix 6)
Any one of appendixes 1 to 5, wherein the second inlet of the reservoir tank is provided at a position farther from the outlet of the reservoir tank than the first inlet. The cooling device described.
(Appendix 7)
The cooling device according to any one of appendices 1 to 6, wherein the vapor channel and the liquid channel extend in directions orthogonal to each other.

(Appendix 8)
The steam channel is a first steam channel provided on the upper side of the porous body, and a second steam channel provided on the lower side of the porous body,
The cooling device according to any one of appendices 1 to 7, wherein the liquid channel is a liquid channel provided inside the porous body.

(Appendix 9)
The steam channel is a steam channel provided on one of the upper side and the lower side of the porous body,
The cooling device according to any one of appendices 1 to 7, wherein the liquid passage is a liquid passage provided on the other side of the upper side and the lower side of the porous body.

(Appendix 10)
The cooling device according to any one of appendices 1 to 9, wherein the porous body has an average pore diameter of 10 µm or less.
(Appendix 11)
Electronic components provided on the wiring board;
A cooling device for cooling the electronic component,
The cooling device is
An evaporator having a porous body, having a vapor channel and a liquid channel separated by the porous body, and evaporating a liquid-phase working fluid;
A condenser that condenses the gas-phase working fluid;
A reservoir tank for storing the liquid-phase working fluid;
A steam pipe connecting the outlet of the steam flow path of the evaporator and the inlet of the condenser;
A liquid pipe connecting the outlet of the condenser and the first inlet of the reservoir tank;
A liquid supply pipe connecting an outlet of the liquid reservoir tank and an inlet of the liquid flow path of the evaporator;
A liquid return pipe connecting an outlet of the liquid flow path of the evaporator and a second inlet of the liquid storage tank;
Liquid transport means interposed in the liquid supply pipe;
A flow rate adjusting valve provided in the liquid return pipe for adjusting the flow rate of the liquid-phase working fluid flowing in the liquid return pipe;
A temperature sensor provided in the evaporator or a heat source thermally connected to the evaporator;
A control unit for controlling the opening of the flow rate adjustment valve based on information from the temperature sensor,
The electronic device is characterized in that the electronic component is thermally connected to the evaporator.

(Appendix 12)
The cooling device according to appendix 11, wherein the control unit controls the output of the liquid transporting unit based on information from the temperature sensor.
(Appendix 13)
13. The electronic device according to appendix 11 or 12, wherein the porous body is a resin porous body.

(Appendix 14)
14. The electronic device according to any one of appendices 11 to 13, wherein a heat radiating member is provided in the liquid return pipe.
(Appendix 15)
A condenser comprising the condenser and cooling means;
The electronic device according to any one of appendices 11 to 14, wherein a part of the liquid return pipe is provided inside the condensing device.

(Appendix 16)
Any one of appendixes 11 to 15, wherein the second inlet of the liquid reservoir tank is provided at a position farther from the outlet of the liquid reservoir tank than the first inlet. The electronic device described.
(Appendix 17)
The steam channel is a first steam channel provided on the upper side of the porous body, and a second steam channel provided on the lower side of the porous body,
The electronic device according to any one of appendices 11 to 16, wherein the liquid flow path is a liquid flow path provided inside the porous body.

(Appendix 18)
The steam flow path is provided on one side of the upper side and the lower side of the porous body,
The electronic device according to any one of appendices 11 to 16, wherein the liquid flow path is provided on the other side of the upper side and the lower side of the porous body.
(Appendix 19)
The evaporator is provided on a first vapor channel provided on one of the upper side and the lower side of the first porous body, and on the other side of the upper side and the lower side of the first porous body. A first evaporator including a first liquid channel; a second vapor channel provided on one of the upper side and the lower side of the second porous body; and an upper side of the second porous body; A second evaporator provided with a second liquid flow path provided on the other side of the lower side,
The side where the vapor flow path of the first evaporator is provided on the back side of the electronic component is thermally connected, and the vapor flow path of the second evaporator is provided on the front side of the electronic component. The electronic device according to any one of appendices 11 to 16, wherein the connected side is thermally connected.

(Appendix 20)
20. The electronic device according to any one of appendices 11 to 19, wherein the porous body has an average pore diameter of 10 μm or less.

DESCRIPTION OF SYMBOLS 1 Evaporator 1X 1st flat plate type evaporator 1Y 2nd flat plate type evaporator 2 Condenser 3 Liquid reservoir tank 3A 1st inlet 3B 2nd inlet 3C Outlet 3X-3Z Wall surface 4 Steam pipe 5 Liquid pipe 6 Liquid supply pipe 7 Liquid return pipe 8 Liquid transport pump 8A Suction port 8B Discharge port 9 Heating element 10 Steam flow channel 11 Liquid flow channel 12 Wick 12A Flat plate portion 12AX Resin porous plate 12B Protrusion portion 12C Through hole 12CX Recess 13 Case 14 Cavity 15 Groove 20 Electronic device 21 Electronic component 22 Cooling device 23 Wiring board (printed board)
24 Flat heating element 25 Liquid inlet side manifold 26 Liquid outlet side manifold 30 3D stacked package 31, 31X Semiconductor chip 40, 40X, 40Y Flow rate adjusting valve 40A, 40XA, 40YA Valve part 40B, 40XB, 40YB Drive part 41, 41X, 41Y Temperature sensor 42 Control unit

Claims (9)

An evaporator having a porous body, having a vapor channel and a liquid channel separated by the porous body, and evaporating a liquid-phase working fluid;
A condenser that condenses the gas-phase working fluid;
A reservoir tank for storing the liquid-phase working fluid;
A steam pipe connecting the outlet of the steam flow path of the evaporator and the inlet of the condenser;
A liquid pipe connecting the outlet of the condenser and the first inlet of the reservoir tank;
A liquid supply pipe connecting an outlet of the liquid reservoir tank and an inlet of the liquid flow path of the evaporator;
A liquid return pipe connecting an outlet of the liquid flow path of the evaporator and a second inlet of the liquid storage tank;
Liquid transport means interposed in the liquid supply pipe;
A flow rate adjusting valve provided in the liquid return pipe for adjusting the flow rate of the liquid-phase working fluid flowing in the liquid return pipe;
A temperature sensor provided in the evaporator or a heat source thermally connected to the evaporator;
And a controller that controls the opening of the flow rate adjustment valve based on information from the temperature sensor.   The cooling device according to claim 1, wherein the control unit controls an output of the liquid transporting unit based on information from the temperature sensor.   The cooling device according to claim 1, wherein the porous body is a resin porous body.   The cooling device according to claim 1, wherein a heat radiating member is provided in the liquid return pipe. A condenser comprising the condenser and cooling means;
The cooling device according to claim 1, wherein a part of the liquid return pipe is provided inside the condensing device.   The said 2nd inlet_port | entrance of the said reservoir tank is provided in the position far from the said exit of the said reservoir tank rather than the said 1st inlet_port | entrance, The any one of Claims 1-5 characterized by the above-mentioned. The cooling device according to 1.   The cooling device according to claim 1, wherein the vapor channel and the liquid channel extend in directions orthogonal to each other.   The cooling device according to claim 1, wherein the porous body has an average pore diameter of 10 μm or less. Electronic components provided on the wiring board;
A cooling device for cooling the electronic component,
The cooling device is
An evaporator having a porous body, having a vapor channel and a liquid channel separated by the porous body, and evaporating a liquid-phase working fluid;
A condenser that condenses the gas-phase working fluid;
A reservoir tank for storing the liquid-phase working fluid;
A steam pipe connecting the outlet of the steam flow path of the evaporator and the inlet of the condenser;
A liquid pipe connecting the outlet of the condenser and the first inlet of the reservoir tank;
A liquid supply pipe connecting an outlet of the liquid reservoir tank and an inlet of the liquid flow path of the evaporator;
A liquid return pipe connecting an outlet of the liquid flow path of the evaporator and a second inlet of the liquid storage tank;
Liquid transport means interposed in the liquid supply pipe;
A flow rate adjusting valve provided in the liquid return pipe for adjusting the flow rate of the liquid-phase working fluid flowing in the liquid return pipe;
A temperature sensor provided in the evaporator or a heat source thermally connected to the evaporator;
A control unit for controlling the opening of the flow rate adjustment valve based on information from the temperature sensor,
The electronic device is characterized in that the electronic component is thermally connected to the evaporator.