JP2002314279A - Cooling equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling equipment which can keep a high cooling performance even after the long-time service. SOLUTION: The cooling equipment comprises a pump 11, heat sink 12 connected to the pump 11, heat radiator 13 connected to both the heat sink 12 and the pump 11; flow channel 14 which passes through the insides of the pump 11, the heat sink 12, and the heat radiator 13 and which connects all of these to form a closed circuit circulation cycle; and liquid cooling medium circulated in the flow channel 14. The liquid cooling medium is more pressurized with the increase in temperature of itself.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device used for portable electronic equipment such as a notebook personal computer (hereinafter referred to as a notebook personal computer).

[0002]

2. Description of the Related Art A conventional cooling device is disclosed in JP-A-2001-24.
372 is known.

FIG. 11 is a layout diagram when a conventional cooling device is incorporated in a notebook personal computer incorporating the conventional cooling device. 11, 1 is a main body of a notebook computer, 2 is a heating element such as a CPU, 3 is a heat transfer pad, 4 is a heat absorber, 5
Denotes a pump, 6 denotes a radiator, 7 denotes a display unit of a notebook computer, and 8 denotes a flow path. The flow path 8 is filled with a water-based or chlorofluorocarbon-based liquid refrigerant.

Next, the operation of the cooling device will be described.

When the notebook personal computer is used, power is supplied to the pump 5 and the pump 5 is operated to pump the liquid refrigerant. The closed circuit circulation of the pump 5, the heat sink 4, the radiator 6, and the pump 5 connected by the flow path 8 The liquid refrigerant circulates in the cycle. Therefore, the liquid refrigerant pushed out by the pump 5 absorbs the heat of the heating element 2 by the heat absorber 4, moves to the radiator 6, radiates heat, is cooled again, and returns to the pump 5. By repeating this, the heat generated in the notebook computer is released to the outside.

[0006]

When this cooling device is used for a long time, the liquid refrigerant is heated and gas is generated, and the generated gas flows into the pump 5 together with the liquid refrigerant, and the flow rate of the liquid refrigerant is reduced. There was a problem that the cooling capacity deteriorated.

Accordingly, the present invention has been made to solve this problem, and an object of the present invention is to provide a cooling device having an excellent cooling effect even when used for a long time.

[0008]

In order to achieve this object, the present invention has the following arrangement.

[0009] The invention described in claim 1 of the present invention is, in particular,
The liquid refrigerant circulating in the flow path forming the closed circuit circulation cycle is pressurized with an increase in temperature, and the solubility of gas in the liquid refrigerant increases, so that generation of gas from the liquid refrigerant is suppressed, The cooling efficiency is prevented from deteriorating.

[0010] The invention described in claim 2 of the present invention is, in particular,
The rate of change in volume with respect to the change in temperature of the liquid refrigerant is larger than the change in volume due to the change in the temperature of the flow path.Since the solubility of the gas in the liquid refrigerant increases as the temperature rises, generation of gas can be suppressed. In addition, deterioration of the cooling efficiency can be prevented.

[0011] The invention described in claim 3 of the present invention is, in particular,
The rigidity of a part of the flow path is made lower than that of the other part, and the cooling device of the present invention can suppress the generation of gas as the pressure applied to the liquid refrigerant is higher. With the above configuration, the pressure in the closed-circuit circulation cycle can be controlled to an appropriate range because there is a possibility that the pressure-sensitive member may be damaged.

The invention described in claim 4 of the present invention particularly provides
A non-shrinkable substance that is in contact with the liquid refrigerant and does not penetrate the liquid refrigerant inside the flow path, and a contractile substance that is in non-contact with the liquid refrigerant and in contact with the non-shrinkable substance. Although the cooling device can suppress the generation of gas from the liquid refrigerant as the pressure applied to the liquid refrigerant is higher, the pump or the like may be damaged if the pressure of the liquid refrigerant is too high. In addition, the pressure in the closed circuit circulation cycle can be controlled in an appropriate range while maintaining the cooling effect.

The invention according to claim 5 of the present invention particularly provides
The flow path is provided with a contractible solid, and the cooling device of the present invention can suppress the generation of gas from the liquid refrigerant as the pressure applied to the liquid refrigerant is higher, but the pressure of the liquid refrigerant is too high With such a configuration, the pressure in the closed circuit circulation cycle can be controlled to an appropriate range while maintaining the cooling effect because the pump and the like may be damaged.

[0014] The invention according to claim 6 of the present invention particularly provides
A diaphragm bonded with a piezoelectric element as a pump,
A pump having a pump chamber surrounded by at least one valve serving as an inlet and an outlet of a liquid refrigerant is used. A piezoelectric pump can be configured as a thin pump, and thus is suitable for use in electronic devices such as a notebook computer. However, when used for a long period of time, gas enters the pump chamber, and changes in the volume of the pump chamber are absorbed by expansion and contraction of the gas, causing a problem that the flow rate of the liquid refrigerant is significantly deteriorated. Can suppress the generation of gas from the liquid, so that even if the piezoelectric pump is used, the flow rate of the liquid refrigerant can be prevented from deteriorating, and the cooling efficiency can be improved for a long time. A cooling device suitable for use.

[0015] The invention described in claim 7 of the present invention particularly provides
The liquid refrigerant circulating in the flow path forming the closed circuit circulation cycle is not in contact with the outside air and the amount of gas dissolved therein is smaller than the gas solubility at the maximum use temperature of the liquid refrigerant, Even if the liquid refrigerant is used for a long time and the temperature of the liquid refrigerant rises, generation of gas can be suppressed and cooling efficiency can be prevented from being deteriorated.

The invention according to claim 8 of the present invention particularly provides
The pump has a diaphragm in which a piezoelectric element is bonded, and a pump chamber surrounded by at least one valve serving as an inlet and an outlet for a liquid refrigerant. The present invention is suitable for use in equipment, but when used for a long time, gas enters the pump chamber, and changes in the volume of the pump chamber are absorbed by expansion and contraction of the gas. Since the cooling device can suppress the generation of gas from the liquid refrigerant, even if the piezoelectric pump is used, it is possible to prevent the flow rate of the liquid refrigerant from deteriorating, and to have excellent cooling efficiency for a long time. Therefore, the cooling device is suitable for use in small and thin electronic devices.

The invention according to claim 9 of the present invention particularly provides
The liquid refrigerant is pressurized so that the amount of gas dissolved in the liquid refrigerant circulating in the flow path forming the closed circuit circulation cycle is smaller than the solubility of the gas at the maximum use temperature of the liquid refrigerant. Even if the liquid refrigerant is used for a long time and the temperature of the liquid refrigerant rises, generation of gas can be suppressed, and deterioration of cooling efficiency can be suppressed.

According to a tenth aspect of the present invention, in particular, the pump comprises a diaphragm having a piezoelectric element bonded thereto;
It has a pump chamber surrounded by at least one valve that serves as an inlet and an outlet for a liquid refrigerant. A piezoelectric pump is suitable for use in electronic devices such as a notebook computer because it can constitute a thin pump. When used for a long time, gas enters the pump chamber, and the change in volume of the pump chamber is absorbed by expansion and contraction of the gas, causing a problem that the flow rate of the liquid refrigerant is significantly deteriorated. Since the generation can be suppressed, the flow rate of the liquid refrigerant can be prevented from deteriorating even when the above-described piezoelectric pump is used, and the cooling efficiency is excellent for a long time. Cooling device.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic view of a notebook personal computer incorporating a cooling device according to the first to sixth embodiments of the present invention, wherein 11 is a pump, 12 is a heat absorber connected to a pump 11, and 13 is a pump. A radiator 11 and a radiator connected to the heat absorber 12 are flow paths connected between the pump 11 and the heat absorber 12, between the heat absorber 12 and the radiator 13, and between the radiator 13 and the pump 11. The flow path 14 allows the pump 11-the heat absorber 12
-A radiator 13-forms a closed circuit circulation cycle of the pump 11 and fills it with a liquid refrigerant to constitute a cooling device. This cooling device has a configuration in which the liquid refrigerant is not in contact with the outside air.

Reference numeral 15 denotes a main body of the notebook computer in which the pump 11 and the heat absorber 12 are housed. Reference numeral 16 denotes a heating element such as a CPU, which is in close contact with the heat absorber 12 via a heat transfer pad 16a. Reference numeral 17 denotes a display unit in which the radiator 13 is housed.

FIG. 2 is a cross-sectional view of a pump used in the first to sixth embodiments, wherein 21 is a piezoelectric vibrator having electrodes on both surfaces, and 22 is a piezoelectric vibrator 21 attached to one surface. Metal diaphragm, 23a is first valve holding plate, 23b
Is a second valve holding plate, 24a is a first valve, 24b is a second valve, 2
5 is a pump chamber, 26 is a housing, 27a is a liquid refrigerant inlet,
27b is a liquid refrigerant outlet, 28 is a lead terminal having one end connected to the piezoelectric vibrator 21, and 29 is a power supply. In the figure, arrows indicate the direction in which the liquid refrigerant flows.

The pump chamber 25 includes a ring-shaped housing 26, a metal diaphragm 22 having an outer peripheral portion supported above the housing 26 so that the piezoelectric vibrator 21 is exposed to the surface, and
This is a space surrounded by the first and second valves 24a and 24b supported below and the first and second valve pressing plates 23a and 23b.

The inlet and outlet 27a, 27b for the liquid refrigerant are provided below the first and second valves 24a, 24b.

FIG. 3 shows a heat absorber 12 used in the first embodiment.
FIG. 3 is an exploded perspective view of the device, 31 is a lid, 32 is a housing, 33a,
33b is an entrance and an exit. As shown in the figure, the opening of the housing 32 is sealed with a lid 31 made of resin via a sealing layer (not shown). The opposite sides of the housing 32 are formed with liquid refrigerant inlets and outlets 33a and 33b. The liquid refrigerant is pumped from the inlet 33a to the outlet 33b via the inside of the housing 32. When the liquid refrigerant passes through the inside of the housing 32, the heat of the heating element 16 is absorbed. The inlet 33 a is connected to the outlet 27 b of the pump 11, and the outlet 33 b is connected to the inlet of the radiator 13 via the flow path 14. The heat absorber 12 is provided on the upper surface of the heating element 16 with a heat transfer pad 16a.
Mounted via

FIG. 4 shows a radiator 13 used in the first embodiment.
Is a cross-sectional view, 41 is a flow path, 42a and 42b are an inlet and an outlet, and 43 is a housing.

The flow channel 41 is a single long elastic tube formed by bonding thin plates of stainless steel or the like having good heat conductivity. The radiator 13 is attached to the inner wall surface of the display unit 17 via an adhesive layer having excellent heat conductivity.

FIG. 5 shows the relationship between the flow rate of the cooling device according to the first embodiment and the flow rate of the pump of the cooling device described in the prior art and the passage of time.

FIG. 6 shows a solubility curve of air in water. The solid line shows the air pressure of 1 × 10 ⁵ Pa, and the dotted line shows the air pressure of 2 × 10 ⁵ Pa. Since the actual pressure of the air is a partial pressure of the vapor pressure of water, when the temperature increases, the vapor pressure increases and the partial pressure of the air decreases, so that the solubility further decreases.

In the first embodiment, water having a tendency similar to that shown in FIG. 6, water or a mixture of water and a solvent such as ethylene glycol to lower the freezing point, or a fluorine-based inert liquid is used. That is, the solubility of the liquid refrigerant in the first embodiment decreases as the temperature increases, and gas dissolved in the liquid refrigerant is generated in the liquid refrigerant. The solubility is proportional to the pressure of the gas in contact with the liquid refrigerant, and the higher the pressure of the gas in contact, the higher the solubility. In the first embodiment, an object is to suppress generation of gas from the liquid refrigerant and decrease in cooling efficiency. Therefore, in Embodiment 1, there is a difference in the absolute value of the amount of dissolution, but FIG.
A liquid refrigerant having the same tendency as described above was used.

Therefore, by using a liquid refrigerant whose behavior at a temperature change is known in advance, it is possible to design a cooling device capable of suppressing the characteristic deterioration of the pump 11 at a temperature change.

FIG. 7 shows a flow path 14 according to the first embodiment.
FIG. 5 is a partially enlarged cross-sectional view of FIG.
The rigidity was made smaller than other parts of the flow path 14. Channel 14
Is made of stainless steel or the like, and the flow path weak rigid portion 52 is made of a material having a lower rigidity than stainless steel or a thinner material of the same material than other portions, and is provided at at least one place in the cooling device. Further, the flow path 14 may be formed of a material having a volume change rate smaller than the volume change rate of the liquid refrigerant when the temperature rises.

The operation of the cooling device configured as described above will be described with a focus on the pump 11 with reference to the drawings.

When an AC voltage is applied to the piezoelectric vibrator 21 from the power supply 29 via the lead terminal 28, the piezoelectric vibrator 21 bends upward. At this time, first, the open end of the first valve 24a moves upward, a gap is formed between the first valve holding plate 23a and the first valve 24a, and the liquid refrigerant flowing from the inlet 27a flows into the pump chamber 25 from this gap. I do. At this time, the second valve 24b is kept closed by the second valve holding plate 23b located above. Next, when the piezoelectric vibrator 21 bends downward, the second valve 24
b moves downward, and the second valve holding plate 23b and the second
A gap is generated between the pump chamber 2 and the valve 24b.
The liquid refrigerant of No. 5 flows out and is pressure-fed from the outlet 27b to the heat absorber 12 side (the moving direction of the liquid refrigerant is indicated by an arrow in FIG. 2).

The above operation is repeatedly performed by continuously bending the piezoelectric vibrator 21 in the vertical direction, and the liquid refrigerant is formed by a closed circuit circulation cycle of the pump 11, the heat absorber 12, the radiator 13, and the pump 11. Circulation in the cooling device.

The liquid refrigerant flows into the pump 11 from the radiator 13 and flows out to the heat absorber 12 so that the liquid refrigerant has the lowest temperature in the pump 11. This is to prevent the characteristics of the pump 11 from changing with temperature.

Next, the liquid refrigerant pushed out by the pump 11 absorbs the heat of the heating element 16 in the heat absorber 12, moves to the radiator 13, radiates heat in the radiator 13, is cooled again, and returns to the pump 11. Come. By repeating this, the heat generated in the notebook computer is released to the outside.

The characteristics of the cooling device configured as described above will be described.

FIG. 5 shows the relationship between the flow rate of the pump of the cooling device of the first embodiment and the flow rate of the pump of the cooling device described in the prior art and the passage of time.

Therefore, as can be seen from this figure, the cooling device of the first embodiment exhibits an excellent cooling effect without deterioration of the flow rate of the pump 11 even when used continuously for a long time.

That is, the liquid refrigerant in the first embodiment expands as the temperature rises, but the volume change rate is larger than the volume change rate due to the temperature change of the flow path 14, and as a result, the liquid refrigerant becomes Since the gas is in a pressurized state, the solubility of the gas increases, and the generation of gas from the liquid refrigerant can be suppressed, so that the liquid refrigerant circulates as it was at the start of use without gas remaining in the pump chamber 25 of the pump 11. Therefore, cooling can be stably performed.

As described above, in the cooling device according to the first embodiment, since the liquid refrigerant is pressurized as the temperature increases, the solubility of the gas increases with the temperature.
Since the generation of gas from the liquid refrigerant can be suppressed, a stable cooling effect is obtained.

Further, by using a liquid refrigerant which thermally expands like water as well as forming the flow path 14 from a material whose volume change due to temperature change is smaller than the volume change due to temperature change of the liquid refrigerant, the liquid refrigerant is As the temperature increases, the pressure is increased, and the generation of gas can be suppressed.

Further, in the cooling device according to the first embodiment, since the volume change of the liquid refrigerant is larger than the volume change due to the temperature change of the flow path 14, the liquid refrigerant is pressurized as a result. When water is used as the liquid refrigerant, its volume change rate is about 1.5% at room temperature (for example, 25 ° C.) and maximum operating temperature (for example, 60 ° C.). Therefore, when stainless steel is selected as the material of the flow path 14, the volume change of the flow path 14 is very small and the rigidity is large, so that if the pressure of the liquid refrigerant becomes too high, the pump 11 and the like may be damaged.

Accordingly, as shown in FIG. 7, by providing a flow passage weakly rigid portion 52 formed of a material having a lower rigidity than the other flow passage in a part of the flow passage 14, generation of gas from the liquid refrigerant is suppressed. In addition, the liquid refrigerant can be controlled to an appropriate pressure. For example, when the amount of air in which the liquid refrigerant is dissolved in the refrigerant with water is 24
ppm, when the maximum operating temperature is 60 ° C, the flow path 1 at 20 ° C
If the pressure of the liquid refrigerant in 4 is 1 × 10 ⁵ Pa, the solubility of air at the maximum operating temperature of 1 × 10 ⁵ Pa in the liquid refrigerant is 15 ppm, but the vapor pressure of water is 2 × 10 ⁴ Pa.
Since it is Pa, the partial pressure of air is 8 × 10 ⁴ Pa, and the actual gas solubility is 12.1 ppm.

Therefore, if no gas is generated,
The pressure of the body refrigerant is 0.8 × 10^FivePa or more
Refrigerant pressure is required, and the pressure resistance of general pumps
2 × 10^FivePa, the maximum temperature of the liquid refrigerant
0.8 × 10^Five~ 2.0 × 10 ^FiveSo that the pressure is Pa
By designing the flow passage weak rigidity portion 52, the volume expansion of the liquid refrigerant is increased.
The flow path weak rigid part 52 is deformed by tension, and the cooling device is damaged.
Provide a cooling device with a stable cooling effect without
can do.

Further, since the cooling device of the present invention is assumed to be incorporated in a thin electronic device such as a notebook personal computer, a metal diaphragm having a piezoelectric vibrator 21 as shown in FIG. 22 and a pump chamber 25 surrounded by the first and second valves 24a and 24b.
Even if a thin pump utilizing the change in volume of the pump is used, a stable cooling effect can be obtained for a long time.

(Embodiment 2) The second embodiment of the present invention will be described below with reference to the second embodiment.

Also in the second embodiment, the same cooling device, pump 11, heat sink 12, radiator 13, and liquid refrigerant shown in FIGS.

FIG. 8 is a partially enlarged cross-sectional view of the flow path 14 in the second embodiment. 53 is a contractible substance such as air that contracts with a change in pressure. 54 is a liquid refrigerant that does not react with the liquid refrigerant. It is a non-shrinkable substance such as oil that does not penetrate. Both the contractible substance 53 and the non-contractible substance 54 may be in any state of gas, liquid and solid. However, the shrinkable material 53 is always entirely covered with the non-shrinkable material 54 or is covered with the non-shrinkable material 54 and the flow path 14 and is isolated from the liquid refrigerant.

In the second embodiment, the first embodiment
Only the parts different from the above will be described.

As described in the first embodiment, the volume change of the liquid refrigerant is larger than the volume change due to the temperature change of the flow path 14. Therefore, for example, when water is used as the liquid refrigerant, and when all the channels 14 are formed of stainless steel having the same thickness, the pressure of the liquid refrigerant becomes extremely high with the temperature rise,
The pump 11 and the like may be damaged.

Therefore, in the first embodiment, the flow path weak rigid portion 52 is formed in a part of the flow path 14. In the second embodiment, the generation of gas from the liquid refrigerant is suppressed while the liquid flow is suppressed. A method for controlling the refrigerant to an appropriate pressure will be described.

That is, as shown in FIG. 8, when the pressure of the liquid refrigerant becomes too high as the temperature rises,
3 contracts, relieves the pressure of the liquid refrigerant, and controls the liquid refrigerant to an appropriate pressure. Therefore, without damaging the cooling device,
A cooling device having a stable cooling effect for a long time can be provided.

As described above, the cooling device according to the second embodiment includes the non-shrinkable substance 54 which is in contact with the liquid refrigerant but does not penetrate into the part of the flow path 14, Contractile substance 53 contacted with compressible substance 54
The pressure change caused by the temperature rise of the liquid refrigerant can be reduced, and the liquid refrigerant can be controlled to an appropriate pressure.

Third Embodiment The third embodiment of the present invention will be described below with reference to the third embodiment.

Also in the third embodiment, the same cooling device, pump 11, heat sink 12, radiator 13, and liquid refrigerant shown in FIGS. 1 to 4 as those in the first embodiment are used, and the description thereof will be omitted.

FIG. 9 is a partially enlarged cross-sectional view of the flow channel 14 in the third embodiment. Reference numeral 55 denotes a contractible solid that does not react with a liquid refrigerant such as silicon rubber.

Also in the third embodiment, the first embodiment
Only the parts different from the above will be described.

As described in the first embodiment, the volume change of the liquid refrigerant is larger than the volume change due to the temperature change of the flow path 14. Therefore, for example, when water is used as the liquid refrigerant, and when all the channels 14 are formed of stainless steel having the same thickness, the pressure of the liquid refrigerant becomes extremely high with the temperature rise,
The pump 11 and the like may be damaged.

Therefore, in the first embodiment, the flow path weak rigid portion 52 is formed in a part of the flow path 14. In the third embodiment, the generation of gas from the liquid refrigerant is performed by another method. While controlling, the liquid refrigerant is controlled to an appropriate pressure.
That is, when the pressure of the liquid refrigerant becomes too high as the temperature rises as shown in FIG. 9, the contractible solid 55 contracts, so that the liquid refrigerant can be controlled to an appropriate pressure.

As described above, in the cooling device according to the third embodiment, by providing the contractible solid 55 in a part of the flow path 14, the liquid refrigerant is controlled at an appropriate pressure, and the cooling device is prevented from being damaged. It has a cooling effect that is stable over time.

(Embodiment 4) A fourth embodiment of the present invention will be described below.

In the fourth embodiment as well, the same cooling device, pump 11, heat absorber 12, radiator 13, and flow path 14 as in the first embodiment shown in FIGS.

In the fourth embodiment, the amount of gas dissolved in the liquid refrigerant at room temperature is made smaller than the solubility of the liquid refrigerant at the maximum temperature in advance, and then the liquid refrigerant is filled into the flow path. By making it non-contact, no gas is generated from the liquid refrigerant even if the temperature rises, and a stable cooling effect can be obtained. For example, in the case where water is used as the liquid refrigerant and the maximum temperature is 60 ° C., the gas dissolved in the liquid refrigerant is taken into consideration as shown in FIG. The amount of 1
By setting the concentration to 2.1 ppm or less, it is possible to provide a cooling device that does not generate gas even at the highest temperature of the liquid refrigerant and has a stable cooling effect.

(Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described with reference to FIGS. Also in the fifth embodiment, the cooling device, the pump 11, and the heat absorber 1 shown in FIGS.
2. Since the radiator 13 and the flow path 14 are used, the description thereof will be omitted.

In the fifth embodiment, the temperature is increased by applying pressure so that the amount of gas dissolved in the liquid refrigerant is smaller than the solubility even at the maximum temperature of the liquid refrigerant, so that the liquid refrigerant is not in contact with the gas. Even if it rises, the generation of gas from the liquid refrigerant is suppressed. For example, when water is used as the liquid refrigerant and the maximum temperature is 60 ° C., the liquid refrigerant has a maximum pressure of 1.6 × 10 ⁵ Pa or more as shown by the solubility of air in water in FIG. A cooling device that does not generate gas even at a temperature and has a stable cooling effect can be provided.

(Embodiment 6) A sixth embodiment of the present invention will be described below, particularly with reference to the first, seventh and ninth aspects of the present invention. FIG. 10 is a perspective view of a cooling device according to the sixth embodiment, in which 62 is a heat absorber, 63 is a pump, and 64 is a radiator. The pump 6 is provided on the surface of the plate-shaped radiator 64.
3. The heat absorber 62 is installed. At the time of operation of the cooling device, the pump 63 is supplied with power and operated to pump the liquid refrigerant, and the pump 63-the heat absorber 62-the radiator 64-the pump 6
The liquid refrigerant circulates in the closed circuit circulation cycle of No. 3. The pump 63 and the heat sink 62 are connected to each other, the heat absorber 62 and the radiator 64 are connected to each other, and the radiator 64 and the pump 63 are connected to each other by flow paths.

Therefore, the liquid refrigerant extruded by the pump 63 absorbs the heat of a heating element (not shown) such as a CPU by the heat absorber 62, moves to the radiator 64, radiates heat, is cooled again, and is cooled again. Come back to. By repeating this, the heat generated by the heating element (not shown) is released to the outside.

Although the liquid refrigerant expands as the temperature rises, the rate of change in volume of the liquid refrigerant is greater than the rate of change in volume of the flow path due to temperature change. As a result, the liquid refrigerant is pressurized. Since the solubility of the gas increases and the generation of the gas from the liquid refrigerant can be suppressed, the liquid refrigerant circulates as it did at the start of use, so that the liquid refrigerant can be cooled stably.

[0071]

As described above, in the cooling device of the present invention, the liquid refrigerant circulating in the flow path forming the closed circuit circulation cycle is pressurized as the temperature rises. Since the solubility of the gas increases, the generation of the gas from the liquid refrigerant is suppressed, and the cooling efficiency is prevented from deteriorating. As a result, even when used for a long time, the cooling efficiency is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a notebook computer having a built-in cooling device according to Embodiments 1 to 5 of the present invention.

FIG. 2 is a sectional view of the pump according to the first to fifth embodiments of the present invention.

FIG. 3 is an exploded perspective view of a heat absorber according to Embodiments 1 to 5 of the present invention.

FIG. 4 is a cross-sectional view of a radiator according to Embodiments 1 to 5 of the present invention.

FIG. 5 is a curve diagram showing a temporal change in the flow rate of the liquid refrigerant in the first to fifth embodiments of the present invention.

FIG. 6 is a curve diagram showing solubility of air in water.

FIG. 7 is an enlarged sectional view of a flow channel according to the first embodiment of the present invention.

FIG. 8 is an enlarged sectional view of a flow channel according to the second embodiment of the present invention.

FIG. 9 is an enlarged sectional view of a flow channel according to a third embodiment of the present invention.

FIG. 10 is a perspective view of a cooling device according to a sixth embodiment of the present invention.

FIG. 11 is a perspective view of a notebook computer incorporating a conventional cooling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Pump 12 Heat sink 13 Radiator 14 Flow path 15 Main body 16 Heating element 16a Heat transfer pad 17 Display part 21 Piezoelectric vibrator 22 Metal diaphragm 23a First valve holding plate 23b Second valve holding plate 24a First valve 24b Second valve Reference Signs List 25 pump chamber 26 housing 27a inlet 27b outlet 28 lead terminal 29 power supply 31 lid 32 housing 33a inlet 33b outlet 41 flow passage 42a inlet 42b outlet 43 housing 52 flow passage weak rigid part 53 contractile material 54 non-shrinkable material 55 Shrinkable solid 62 Heat sink 63 Pump 64 Heat radiator

Continued on the front page (72) Inventor Yuyuki Okano 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Person Atsushi Komatsu 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (Reference) 3L044 BA06 CA14 DB02 FA02 FA04 5E322 DA01 DA02 EA11 FA01

Claims (10)

[Claims] 1. A pump, a heat sink connected to the pump, a radiator connected to the heat sink and the pump, and a passage passing through and between the pump, the heat sink, and the radiator. A flow path connected to form a closed circuit circulation cycle, and a liquid refrigerant that circulates through the flow path and decreases the solubility of gas with an increase in temperature. The liquid refrigerant is configured to be pressurized with an increase in temperature. Cooling equipment. 2. Volume expansion due to temperature rise of the liquid refrigerant is as follows:
2. The cooling device according to claim 1, wherein the volume expansion is larger than a volume expansion due to a temperature rise of the flow path. 3. The cooling device according to claim 2, wherein the rigidity of a part of the flow passage is lower than that of the other part. 4. A flow path is provided with a substance that is in contact with the liquid refrigerant and cannot penetrate the liquid refrigerant and a contractile substance that is not in contact with the liquid refrigerant and is in contact with the substance.
The cooling device according to claim 1. 5. The cooling device according to claim 2, wherein a contractile solid is provided in the flow path. 6. The cooling device according to claim 1, wherein the pump has a diaphragm on which a piezoelectric element is bonded, and a pump chamber surrounded by at least one valve serving as an inlet and an outlet for a liquid refrigerant. 7. A pump, a heat absorber connected to the pump, a heat radiator connected to the heat absorber and the pump, and a gas passing through the pump, the heat absorber, and the heat radiator and between them. A flow path connected to form a closed circuit circulation cycle, and a liquid refrigerant circulating in the flow path, wherein the amount of gas dissolved in the liquid refrigerant is the gas within the operating temperature range of the liquid refrigerant. Cooling device with less than the minimum solubility of. 8. The cooling device according to claim 7, wherein the pump has a diaphragm on which a piezoelectric element is bonded, and a pump chamber surrounded by at least one valve serving as an inlet and an outlet for a liquid refrigerant. 9. A pump, a heat absorber connected to the pump, a heat radiator connected to the heat absorber and the pump, and a gas passing through and between the pump, the heat absorber, and the heat radiator. A flow path connected to form a closed circuit circulation cycle, and a liquid refrigerant circulating in the flow path, wherein the amount of gas dissolved in the liquid refrigerant is the minimum of the gas within the operating temperature range of the liquid refrigerant. A cooling device in which the liquid refrigerant is pressurized so as to have a solubility higher than the solubility. 10. A pump comprising: a diaphragm on which a piezoelectric element is bonded;
10. It has a pump chamber surrounded by two valves.
The cooling device according to claim 1.