JP2001355574A - Piezoelectric pump and cooling device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric pump having reduced height, lesser power consumption, and sufficient reliability, and a cooling device using the same. SOLUTION: The cooling device 10 comprises a piezoelectric vibrator 13 comprising a junction body of a plate like elastic body 12 and a piezoelectric body 11, a pump chamber 19 provided with a closed space formed by a plurality of faces including a face comprising the piezoelectric vibrator and suction and exhaust ports sucking and exhausting refrigerant 7 in and out of the closed space, the piezoelectric pump 1 comprising a driving means driving the piezoelectric vibrator, an endothermic means 3 absorbing heat from an exothermic body 4, a heat exchanger 5 emitting heat outside, and a heat transfer means 6 mutually circulating the refrigerant among the endothermic means, the piezoelectric pump, and the heat exchanger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a heating element in a computer chip, a circuit board, an electronic component, an optical system and the like, and a piezoelectric pump used therefor, and in particular, a CPU chip housed in a narrow space such as a portable device. And related cooling devices.

[0002]

2. Description of the Related Art Most electronic devices, in particular, computer chips and various devices such as CPU chips used in computers, power amplifiers and power supplies generate much heat when they operate. In many cases, cooling is required to ensure stable operation. Usually, a muffin-type fan or a fan having larger blades has been used for cooling such chips.

When various devices and chips are small,
Generally, various types of heat sinks are used. This heat sink is attached to various devices and chips, transfers the heat generated by various devices and chips to the heat sink, and further dissipates from the heat sink into the air current by air cooling with the air current generated by the fin having a large surface area. It is.

[0004]

However, due to demands for higher functions and higher speeds of various devices, as the number of devices used increases, a large amount of power is consumed in a chip and a large amount of heat may be generated. Also, in recent years, the amount of heat generated by CPU chips and the like has been increasing due to a dramatic increase in the operating frequency, and a more efficient cooling device is needed. However, at present, the heat is forced to increase the temperature of the chip and the heat sink, or the airflow speed of the fan is further increased in order to maintain the same temperature. It is easy to increase the airflow velocity, but it leads to an increase in the noise level, which has now reached an unacceptably high level. In addition, an increase in the temperature of the chip impairs the operation stability of the chip and increases the possibility of failure such as abnormal operation. Therefore, an alternative cooling device free from these limitations is required.

[0005] As an alternative to the conventional air cooling system, there is a water cooling system, in which a refrigerant is circulated by an electromagnetic pump. But,
Since it is an electromagnetic pump, a considerable thickness is required to secure the electromagnetic motor part, and there is a problem that it is difficult to reduce the height of the pump part corresponding to the substrate thickness required for portable terminals and the like. . In addition, since a large current flows through the inductor, there is a problem that power consumption is large. In addition, there is a problem that the reliability of the cooling device is low because the motor as the sliding portion of the electromagnetic pump does not have sufficient reliability.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable cooling device and a piezoelectric pump for use in the cooling device, which are reduced in size by reducing the height of the pump section, suppress power consumption, and provide a high reliability.

[0007]

The above object can be attained by the following present invention.

That is, a piezoelectric pump according to the present invention includes a piezoelectric vibrator made of a joined body of a plate-like elastic body and a piezoelectric body, and a closed space formed by a plurality of surfaces including the surface made of the piezoelectric vibrator. It is characterized by comprising a pump chamber having a suction port and a discharge port for sucking and discharging the refrigerant into and from the closed space, and driving means for driving the piezoelectric vibrator.

Further, the piezoelectric pump according to the present invention is the above-mentioned piezoelectric pump, wherein the plate-like elastic body constituting the piezoelectric vibrator has a thermal conductivity of 10 W / m ° C. or more and 440 W / m.
It is characterized by being in the range of m ° C. or less.

[0010] A cooling device according to the present invention includes a piezoelectric vibrator made of a joined body of a plate-like elastic body and a piezoelectric body, a closed space formed by a plurality of surfaces including a surface made of the piezoelectric vibrator, and a refrigerant. A pump chamber having a suction port and a discharge port for suctioning and discharging the closed space, a piezoelectric pump including driving means for driving the piezoelectric vibrator, a heat absorbing means for removing heat from a heating element, and heat to the outside. It is characterized by comprising a heat exchanger for discharging, and a heat transfer means for circulating a refrigerant between the heat absorbing means, the piezoelectric pump and the heat exchanger.

Further, the cooling device according to the present invention is the cooling device, wherein the plate-like elastic body constituting the piezoelectric vibrator has a thermal conductivity of 10 W / m ° C. or more and 440 W / m ° C.
It is characterized in the following range.

Further, the cooling device according to the present invention is the cooling device, wherein the temperature of the refrigerant passing through the piezoelectric pump is controlled by heat conduction through the plate-shaped elastic body constituting the piezoelectric vibrator. By transmitting the temperature of the piezoelectric body substantially to the temperature of the coolant by transmitting the piezoelectric body constituting the piezoelectric vibrator to the piezoelectric body, the piezoelectric constant of the piezoelectric body, at least one of the characteristics consisting of resonance characteristics is changed. The flow rate per unit time of the piezoelectric pump including the piezoelectric vibrator is changed.

Further, the cooling device according to the present invention is the cooling device, wherein the driving means includes temperature sensing means for detecting a temperature of the heating element or a temperature of a refrigerant passing through the piezoelectric pump. Features.

Still further, the cooling device according to the present invention is the cooling device, wherein the driving control means changes a driving frequency or a driving voltage of the piezoelectric vibrator based on the temperature detected by the temperature sensing means. It is characterized by controlling.

Further, a cooling device according to the present invention is the cooling device, wherein the driving means includes at least an oscillation circuit.

Still further, the cooling device according to the present invention is the cooling device, wherein the heat transfer means is a passage through which a refrigerant flows.

Further, the cooling device according to the present invention is the cooling device, wherein the heating element control device for suppressing the heat generation of the heating element when the temperature detected by the temperature sensing means meets a predetermined condition. Is further provided.

The refrigerant is preferably a liquid having a large specific heat. As the refrigerant, for example, water, ethylene glycol, a mixed solution of water and ethylene glycol, or the like can be used.

As means for sucking and discharging the refrigerant into and out of the closed space of the piezoelectric pump, for example, a valve mechanism or a valve mechanism can be used. In this case, the valve mechanism, the valve mechanism, and the like may be of various drive types such as mechanical, electrical, and electromagnetic drive.

As the heat absorbing means, for example, heat sinks of various shapes can be used.

As the heat exchanger, for example, a heat sink or a heat sink can be used.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals indicate the same components throughout.

FIG. 1 is a configuration diagram of a cooling device 10 according to a first embodiment of the present invention. In FIG. 1, 1 is a piezoelectric pump, 2 is a drive circuit, 3 is a heat sink, 4 is a heating element, 5 is a heat exchanger, 6 is a pipe, 7 is a refrigerant, and 8 is a temperature sensor. The piezoelectric pump 1 is driven by a drive circuit 2 and uses the piezoelectric effect to generate a volume change in the pump chamber to flow the refrigerant 7. FIG. 2 is a sectional view of the piezoelectric pump according to the first embodiment, and FIG. 3 is an enlarged view of a part of the piezoelectric pump for explaining the operation of the piezoelectric pump. 2 and 3, 11
Is a piezoelectric body, 12 is a plate-like elastic body, 13 a diaphragm is a piezoelectric vibrator composed of a piezoelectric body 11 and a plate-like elastic body 12, 14 is a drain valve, 15 is a water absorption valve, 16 is a drain nozzle,
17 is a water absorption nozzle, 18 is a housing, and 19 is a pump room. The piezoelectric pump 1 used in the cooling device 10 according to the first embodiment includes a diaphragm 13 that adheres a piezoelectric body 11 to one side of a plate-like elastic body 12, supports a peripheral portion, a housing 18 that holds the diaphragm 13, and a refrigerant. The drain valve 14 and the water intake valve 15 for efficiently entering and exiting the water.

In the cooling device 10 according to the first embodiment, the heat sink 3 is joined to the heating element 4 and the heat generated by the heating element 4 is conducted to the heat sink 3 with high efficiency. A flow path for efficiently transmitting heat to the refrigerant 7 is formed inside the heat sink 3. The heat exchanger 5 also has a flow path similar to that of the heat sink 3, and efficiently radiates heat from the refrigerant 7 to the outside air. The piezoelectric pump 1, the heat sink 3, and the heat exchanger 5 are connected by a pipe 6 in which a refrigerant 7 is sealed. Further, a temperature sensor 8 is arranged near the heating element 4.

As the piezoelectric body 11, a piezoelectric ceramic or a piezoelectric single crystal can be used. Preferably, the temperature dependence of the piezoelectric constant near room temperature is desirable. As the piezoelectric ceramic, for example, lead titanate, barium titanate, lead zirconate titanate (PZT), P
LZT or the like may be used. As the piezoelectric single crystal, for example, lithium tantalate, lithium niobate, or the like may be used. The structure of the piezoelectric body may be a monomorph, bimorph, or the like, or may be a laminated structure.

As the plate-like elastic body 12, any plate-like body having elasticity may be used. Preferably, the elastic plate is preferably capable of rapidly transmitting the heat of the refrigerant passing through the pump chamber to the piezoelectric body by heat conduction. Therefore, the thermal conductivity of the elastic plate is preferably 10 W / m ° C.
More preferably, it is more preferably 20 W / m ° C or more.
As the plate-like elastic body, for example, a copper alloy such as phosphor bronze, a stainless steel alloy, an Invar alloy, or the like can be used.
The thermal conductivity of the plate-like elastic body is 440 W / m ° C. or less.

2 and 3, in the pump chamber 19,
The diaphragm 13 is driven by a drive signal of a predetermined frequency, and the movement changes the volume in the pump chamber 19. When the pressure in the pump chamber 19 becomes negative, water as the refrigerant 7 enters from the water suction nozzle 17 and reaches the pump chamber 19 through the water suction valve 15. When the pressure in the pump chamber 19 becomes positive, the water of the refrigerant 7 is discharged from the drain nozzle 16 through the drain valve 14. By repeating this series of operations, the piezoelectric pump 1 creates a flow from the water intake to the drain. Here, the water suction valve 15 and the drain valve 14 have a backflow prevention structure, and govern the efficiency of the pump.

In the cooling device of the first embodiment, the heating element 4
Is detected by the temperature sensor 8 installed in the vicinity,
The flow rate of the piezoelectric pump 1 per unit time is adjusted according to the temperature. For the adjustment of the flow rate, the following two methods and their combination can be considered.

The first method is to change the driving frequency for driving the piezoelectric vibrator constituting the piezoelectric pump 1 to change the number of times the diaphragm 13 which is a piezoelectric vibrator is fed, and to change the driving frequency. This is a method of controlling the flow rate by using both effects of changing the positional relationship with the resonance point and changing the displacement amount of the diaphragm 13. FIG. 4 shows an example of a driving circuit for realizing this method.
Shown in In FIG. 4, 21 is an oscillation circuit, 22 is a shaping circuit, 23 is an amplifier, 24 is a piezoelectric vibrator, 25 is a control circuit, and 26 is a temperature sensor. The signal of the driving frequency generated by the oscillation circuit 21 is shaped by the shaping circuit 22, boosted in the amplifier 23, and is subjected to the plate-like elastic body (metal thin plate) 1
2 is applied to a piezoelectric vibrator 24 composed of a diaphragm 13 in which a piezoelectric body 11 is bonded to the piezoelectric vibrator 2. The temperature sensor 26
Thereby, the temperature of the heating element 4 is detected at any time. The oscillation circuit 2 is controlled by the control circuit 25 in accordance with the detection result of the temperature of the heating element 4.
1 is controlled. Specifically, when the temperature of the heating element 4 is high, the driving frequency is set to a high frequency,
When the temperature of the heating element 4 is low, the driving frequency is set to a low frequency.

According to the above control, when the heating element 4 is sufficiently cooled or the like, the driving frequency is set to a lower frequency that is farther from the resonance point than the standard driving frequency, so that the amplitude of the diaphragm 13 becomes smaller, and the diaphragm 13 becomes smaller. Can be reduced. Thus, the stress value acting on the piezoelectric body 11 of the diaphragm 13 can be appropriately controlled. Usually, the life of the pump, which is determined by the applied stress and the number of repetitions, can be greatly improved. Further, since the driving frequency is variable, the power consumption of the pump can be reduced, so that the power consumption of the cooling device 10 can also be reduced, and an optimal configuration for a portable device such as a notebook computer can be achieved. Further, by continuing to monitor the output of the temperature sensor 8, it is possible to detect the damage of the cooling device 10, and it is possible to carry out a crisis management without damaging the equipment itself.

In the second method, the driving voltage for driving the piezoelectric vibrator constituting the piezoelectric pump 1 is changed.
This is a method of controlling the flow rate by changing the amplitude of the diaphragm 13 (change in the volume of the pump chamber). FIG. 5 shows an example of a block diagram of a drive circuit for realizing the above method. In FIG. 5, 21 is an oscillation circuit, 22 is a shaping circuit, 23 is an amplifier,
24 is a piezoelectric element, 25 is a control circuit, and 26 is a temperature sensor. The signal of the driving frequency generated by the oscillation circuit 21 is shaped by the shaping circuit 22, boosted in the amplifier 23, and applied to the piezoelectric vibrator 24 composed of the diaphragm 13 in which the piezoelectric body 11 is bonded to the thin metal plate 12. You. Also,
The temperature of the heating element 4 is detected by the temperature sensor 26 as needed. The boosting ratio of the amplifier 23 is controlled by the control circuit 25 according to the detection result. Specifically, when the temperature of the heating element 4 is high, the boosting ratio is set large, and when the temperature of the heating element 4 is low, the boosting ratio is set small.

With the above control, the diaphragm amplitude can be reduced when the heating element 4 is sufficiently cooled. This makes it possible to appropriately control the stress value acting on the piezoelectric body of the diaphragm. Usually, the life of the pump, which is determined by the applied stress and the number of repetitions, can be greatly improved. Further, unnecessary power consumption of the piezoelectric pump can be reduced by changing the driving voltage, so that the power consumption of the cooling device 10 can also be reduced, and a configuration optimal for a portable device such as a notebook computer can be achieved. Further, by continuing to monitor the output of the temperature sensor 26, it is possible to detect the breakage of the cooling device 10, and it is possible to carry out crisis management without damaging the equipment itself. Thus, the above-described method makes it possible to realize a cooling device which has high reliability, significantly reduces power consumption of the cooling device, and can detect breakage of the cooling device while maintaining sufficient cooling performance.

Second Embodiment FIG. 6 shows the structure of a cooling device 10 according to a second embodiment. In FIG. 6, 1 is a piezoelectric pump, 2 is a drive circuit, 3
Is a heat sink, 4 is a heating element, 5 is a heat exchanger, 6 is a pipe, and 7 is a refrigerant. The piezoelectric pump 1 is driven by a drive circuit 2 and uses the piezoelectric effect to generate a volume change in the pump chamber 19 to create a flow of the refrigerant 7.

FIG. 7 shows a sectional view of the piezoelectric pump 1. FIG.
In the figure, 11 is a piezoelectric body, 12 is a thin metal plate, 13 is a diaphragm, 14 is a drain valve, 15 is a water absorption valve, 16 is a drain nozzle, 17 is a water absorption nozzle, 18 is a housing, and 19 is a pump chamber. The pump used in the cooling device according to the present embodiment includes a diaphragm 13 having a peripheral portion supported by bonding a piezoelectric body 11 to one side of a thin metal plate 12 and a housing 1 holding the diaphragm.
8, and a drain valve 14 and a water intake valve 15 for efficiently entering and exiting water as a refrigerant. Furthermore, the structure is such that the heat of the refrigerant 7 in the pump chamber 19 is transmitted to the piezoelectric body 11 via the metal sheet 12 having a high thermal conductivity.

In the cooling device 10 according to the second embodiment, the heat sink 3 is joined to the heat generating element 4, and the heat generated by the heat generating element 4 is transmitted to the heat sink 3 with high efficiency. A flow path for efficiently transmitting heat to the refrigerant 7 is formed inside the heat sink 3. The heat exchanger 5 also has a flow path similar to that of the heat sink 3, and efficiently radiates heat from the refrigerant 7 to the outside air. The piezoelectric pump 1, the heat sink 3, and the heat exchanger 5 are connected by a pipe 6 in which a refrigerant 7 is sealed.

In the piezoelectric pump 1, the diaphragm 1
3 is driven by a drive signal of a predetermined frequency, and its movement changes the volume in the pump chamber 19. When the pump chamber 19 has a negative pressure, water enters from the water suction nozzle 17 and reaches the pump chamber 19 through the water suction valve 15. When the pressure in the pump chamber 19 becomes positive, water is drained from the drain nozzle 16 through the drain valve 14. By repeating this series of operations, this pump creates a flow from the water intake to the drain. Here, the water suction valve 15 and the drain valve 14 have a backflow prevention structure, and govern the efficiency of the pump.

In this cooling device, the heat sink 3 is joined to the heating element 4, and the heat generated by the heating element 4 is conducted to the heat sink 3 with high efficiency. A flow path for efficiently transmitting heat to the refrigerant 7 is formed inside the heat sink 3. The heat exchanger 5 also has the same flow path as the heat sink 3. The piezoelectric pump 1, the heat sink 3, and the heat exchanger 5 are connected by a pipe 6 in which a refrigerant 7 is sealed.

In this cooling device, the heat of the refrigerant 7 is transmitted to the piezoelectric body 11 constituting the piezoelectric pump 1, and
1 is a temperature substantially linked to the temperature of the refrigerant 7. Therefore, the flow rate of the pump can be automatically adjusted according to the fluctuation of the temperature of the refrigerant 7. The automatic flow rate adjustment of the present cooling device will be described with reference to FIGS.

FIG. 8 is a schematic diagram showing how the resonance characteristic of the diaphragm 13 changes depending on the temperature of the piezoelectric body 11. First, when the heat of the refrigerant 7 is transmitted and the temperature of the piezoelectric body 11 increases, the piezoelectric constant of the piezoelectric body 11 changes. In general, a piezoelectric body has a case where the piezoelectric constant increases when the temperature rises, and a case where the piezoelectric constant decreases when the temperature rises.Here, the piezoelectric body whose piezoelectric constant increases when the temperature rises is used. preferable. When such a piezoelectric body 11 is used, when the same voltage is applied to the piezoelectric body 11, the distortion generated in the piezoelectric body increases, and the displacement amount generated in the piezoelectric vibrator 13 increases. In addition, when the temperature increases, the Young's modulus of the piezoelectric body 11 and the thin metal plate 12 forming the piezoelectric vibrator 13 decreases, and FIG.
As shown in (2), the resonance point of the piezoelectric vibrator 13 moves to the lower frequency side. Therefore, even at the same drive frequency, the frequency of the drive point approaches the resonance point, and the displacement of the piezoelectric vibrator 13 increases. These two phenomena occur simultaneously and the refrigerant 7
When the temperature rises, the flow rate of the piezoelectric pump 1 can be automatically increased. On the other hand, when the temperature of the refrigerant 7 is low, each of the refrigerants 7 exhibits the opposite behavior to that at the time of high temperature, and the flow rate can be automatically reduced.

With the above configuration, when the temperature of the refrigerant 7 is low, the amplitude of the diaphragm 13 is reduced, and the stress acting on the diaphragm 13 can be reduced. This allows
The stress value acting on the piezoelectric body 11 of the diaphragm 13 can be appropriately controlled. Usually, the life of the pump, which is determined by the applied stress and the number of repetitions, can be greatly improved. Further, since the flow rate can be controlled without changing the drive voltage and the drive frequency, the piezoelectric pump 1 can be driven by a very simple drive circuit as shown in FIG. Therefore, the configuration can be optimally applied to a portable device such as a notebook computer in which space restrictions are severe.

Further, although not shown here, by installing the temperature sensor 8 near the heating element 4 and continuously monitoring the output of the temperature sensor, it is possible to detect the breakage of the cooling device and to damage the equipment itself. Crisis management that does not allow you to do it is possible. Further, as another method, an electrode for a temperature sensor is formed on a part of the piezoelectric body 11 and the operation of the diaphragm 13 is temporarily stopped to detect a temperature change of the refrigerant 7,
The same effect can be obtained by detecting the pressure applied to the diaphragm 13 or the like.

With this cooling device, while maintaining sufficient cooling performance, high reliability, a simple circuit configuration and a small size can be detected, and furthermore, it is possible to detect damage to the cooling device.

Third Embodiment FIG. 10 shows the configuration of a cooling device 10 according to a third embodiment. 10, 1 is a piezoelectric pump, 2 is a drive circuit,
3 is a heat sink, 4 is a heating element, 5 is a heat exchanger, 6 is a pipe, 7 is a refrigerant, 8 is a temperature sensor, and 9 is a heating element control circuit. The piezoelectric pump 1 is driven by a drive circuit 2 and uses the piezoelectric effect to generate a volume change in a pump chamber 19 to create a flow of the refrigerant 7.

In the cooling device 10 according to the third embodiment, the heat sink 3 is joined to the heating element 4, and the heat generated by the heating element 4 is transferred to the heat sink 3 with high efficiency. A flow path for efficiently transmitting heat to the refrigerant 7 is formed inside the heat sink 3. The heat exchanger 5 also has a flow path similar to that of the heat sink 3, and efficiently radiates heat from the refrigerant 7 to the outside air. The piezoelectric pump 1, the heat sink 3, and the heat exchanger 5 are connected by a pipe 6 in which a refrigerant 7 is sealed.

In this cooling apparatus, the breakage of the cooling apparatus can be detected by installing the temperature sensor 8 near the heating element 4 and continuously monitoring the output of the temperature sensor. Further, for example, when the heating element 4 is a CPU chip or the like, the heating element control circuit 9 controls the amount of heat generated by controlling the processing amount, thereby preventing thermal runaway and the like, and performing risk management without damaging the equipment itself. be able to.

The cooling device 10 is highly reliable, has a simple circuit configuration, is small in size, and detects a breakage of the cooling device while maintaining sufficient cooling performance. Crisis management that does not damage the equipment itself by control can be performed.

[0047]

The cooling device according to the present invention comprises a piezoelectric vibrator comprising a joined body of a plate-like elastic body and a piezoelectric body; a closed space formed by a plurality of surfaces including a surface comprising the piezoelectric vibrator; By using a piezoelectric chamber comprising a pump chamber having a suction port and a discharge port for sucking and discharging the closed space and a driving means for driving the piezoelectric vibrator in the cooling device, while maintaining sufficient cooling performance, A compact cooling device with high reliability, a simple circuit configuration, and a reduced height of the pump section can be provided.

In the cooling device according to the present invention, the plate-like elastic body having a thermal conductivity in the range of 10 to 440 W / m ° C. is used for the piezoelectric vibrator constituting the piezoelectric pump, so that the cooling device passes through the piezoelectric pump. By transmitting the temperature of the refrigerant to the piezoelectric body constituting the piezoelectric vibrator through heat conduction through the plate-like elastic body constituting the piezoelectric vibrator and causing the temperature of the piezoelectric body to substantially interlock with the temperature of the refrigerant, Since the flow rate per unit time of the piezoelectric pump including the piezoelectric vibrator can be changed by changing at least one of the characteristics consisting of the piezoelectric constant of the body and the resonance characteristics, the reliability can be maintained while maintaining sufficient cooling performance. It is possible to provide a small and compact cooling device having a simple structure.

Further, in the cooling device according to the present invention, the driving means includes a temperature sensing means for detecting the temperature of the heating element or the temperature of the refrigerant passing through the piezoelectric pump, and the piezoelectric means is provided based on the temperature detected by the temperature sensing means. By controlling the driving frequency or the driving voltage of the vibrator, the stress value acting on the piezoelectric body of the piezoelectric vibrator can be appropriately controlled. Also, usually
The pump life determined by the applied stress and the number of repetitions can be greatly improved. Further, unnecessary power consumption of the piezoelectric pump can be reduced by changing the drive voltage, so that power consumption as a cooling device can be reduced, and a configuration optimal for a portable device such as a notebook computer can be achieved. Further, by continuing to monitor the output of the temperature sensor, it is possible to detect the damage of the cooling device, and it is possible to carry out crisis management without damaging the equipment itself.

Further, the cooling device according to the present invention further includes a heating element control device for suppressing heat generation of the heating element when the temperature detected by the temperature sensing means meets a predetermined condition. When the cooling device is damaged, it can be detected and the heat generation of the heating element can be controlled to perform risk management that does not damage the device itself.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cooling device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a piezoelectric pump used in the cooling device according to the first embodiment of the present invention.

FIG. 3 is an enlarged sectional view of a part of the piezoelectric pump used in the cooling device according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a drive circuit in the cooling device according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a drive circuit in the cooling device according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram of a cooling device according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a piezoelectric pump used in a cooling device according to a second embodiment of the present invention.

FIG. 8 is a graph showing a relationship between a driving frequency and a gain (sensitivity) of a piezoelectric vibrator of a piezoelectric pump used in a cooling device according to a second embodiment of the present invention.

FIG. 9 is a block diagram of a drive circuit of a cooling device according to a second embodiment of the present invention.

FIG. 10 is a configuration diagram of a cooling device according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric pump 2 Drive circuit 3 Heat sink 4 Heating element 5 Heat exchanger 6 Pipe 7 Refrigerant 8 Temperature sensor 9 Heating element control device 10 Cooling device 11 Piezoelectric material 12 Plate elastic body (metal thin plate) 13 Diaphragm (piezoelectric vibrator) 14 Drain valve 15 Water absorption valve 16 Drain nozzle 17 Water absorption nozzle 18 Housing 19 Pump room 21 Oscillation circuit 22 Shaping circuit 23 Amplifier 24 Piezoelectric vibrator 25 Control circuit 26 Temperature sensor

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H02N 2/00 F04B 45/04 103C (72) Inventor Okano Yuyuki 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Katsunori Moritoki 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) in Matsushita Electric Industrial Co., Ltd. BB04 CC24 CC25 CC30 CC34 CC35 CC36 DB02 EE06 EE12 3H077 AA11 BB10 CC02 CC09 DD06 EE01 EE15 EE21 EE29 EE31 FF01 FF07 FF12 FF22 FF36 FF43 FF52 FF55

Claims (10)

[Claims] 1. A closed space formed by a piezoelectric vibrator made of a joined body of a plate-shaped elastic body and a piezoelectric body, and a plurality of surfaces including a surface formed by the piezoelectric vibrator, and a refrigerant drawn into the closed space, A piezoelectric pump comprising: a pump chamber having a suction port for discharging and a discharge port; and driving means for driving the piezoelectric vibrator. 2. The thermal conductivity of the plate-like elastic body constituting the piezoelectric vibrator is 10 W / m ° C. or more and 440 W / m ° C.
The piezoelectric pump according to claim 1, wherein the piezoelectric pump is in the following range. 3. A closed space formed by a piezoelectric vibrator formed of a joined body of a plate-shaped elastic body and a piezoelectric body, and a plurality of surfaces including a surface formed by the piezoelectric vibrator, and a refrigerant sucked into the closed space.
A pump chamber having a suction port and a discharge port for discharging, a piezoelectric pump including driving means for driving the piezoelectric vibrator, a heat absorbing means for removing heat from a heating element, and a heat exchanger for releasing heat to the outside. And a heat transfer means for circulating a refrigerant between the heat absorbing means, the piezoelectric pump and the heat exchanger. 4. The thermal conductivity of the plate-like elastic body constituting the piezoelectric vibrator is 10 W / m ° C. or more and 440 W / m ° C.
The cooling device according to claim 3, wherein the cooling device is in the following range. 5. The temperature of a refrigerant passing through the piezoelectric pump is transmitted to the piezoelectric body constituting the piezoelectric vibrator by heat conduction through the plate-like elastic body constituting the piezoelectric vibrator to thereby form the piezoelectric body. By substantially interlocking the temperature of the coolant with the temperature of the refrigerant, thereby changing at least one of the piezoelectric constant of the piezoelectric body and a characteristic including a resonance characteristic, and changing the temperature per unit time of the piezoelectric pump including the piezoelectric vibrator. The cooling device according to claim 3, wherein the flow rate is changed. 6. The apparatus according to claim 3, wherein the driving unit includes a temperature sensing unit that detects a temperature of the heating element or a temperature of a refrigerant passing through the piezoelectric pump. Cooling system. 7. The cooling device according to claim 6, wherein the driving unit controls a driving frequency or a driving voltage of the piezoelectric vibrator based on the temperature detected by the temperature sensing unit. 8. The cooling device according to claim 3, wherein the driving unit includes at least an oscillation circuit. 9. The cooling device according to claim 3, wherein the heat transfer means is a passage through which a refrigerant flows. 10. A heating element control device which suppresses heat generation of the heating element when a temperature detected by the temperature sensing means meets a predetermined condition. The cooling device according to claim 1.