JP2003028068A - Piezoelectric pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric pump capable of stably providing a sufficient discharge flow rate suitable for a cooling system of electronic equipment. SOLUTION: The piezoelectric pump includes a casing 1, a diaphragm 2 sealed and fixed on an opening of the casing 1, a piezoelectric vibrator 4 for driving the diaphragm 2, and valves 5a, 5b provided in the casing 1. The casing 1 and the diaphragm 2 are sealed and fixed by a welding part 3. Because the diaphragm 2 and the casing 1 are sealed and fixed by welding, the diaphragm 2 is strongly fixed, and displacement of a center part of the diaphragm 2 increases. Therefore, the discharge flow rate increases. Furthermore, because the diaphragm 2 does not have a flat shape, rigidity of the entire diaphragm 2 is reduced, and displacement of the diaphragm 2 increases. Therefore, the discharge flow rate increases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small piezoelectric pump that constitutes a cooling system for electronic equipment.

[0002]

2. Description of the Related Art A sectional view of a conventional piezoelectric pump is shown in FIG.

A conventional piezoelectric pump has been constructed as shown in FIG. That is, the housing 101 and the flat metal diaphragm 102 are sealed and adhered by the adhesive 103, and the piezoelectric vibrator 104 having electrodes on both surfaces is fixed and fixed to one surface of the diaphragm 102. First inside
The valve 105a and the second valve 105b are the first valve pressing plate 106.
a and the second valve retainer plate 106b. The pump chamber 110 includes a casing 101, a diaphragm 102 having an outer peripheral portion sealed and fixed with an adhesive 103 above the casing 101, and a first valve 105a, a second valve 105b, and a first valve retainer inside the casing 101. It is a space surrounded by the plate 106a and the second valve holding plate 106b.

A liquid inlet 107 is provided in the housing 101.
a, the outlet 107b is the first valve 105a, the second valve 105b
It is provided below. The piezoelectric vibrator 104 is connected to a power source 109 by a lead wire 108.

Next, the operation of the conventional piezoelectric pump will be described. When an AC voltage is applied from the power supply 109 to the piezoelectric vibrator 104 via the lead wire 108, the piezoelectric vibrator 10
4 is continuously deformed in the vertical direction, and the diaphragm 102 is continuously bent in the vertical direction. Thereby, the pump chamber 110
The inside is continuously depressurized and pressurized, the first valve 105a and the second valve 105b are continuously opened and closed alternately, and the liquid flows in from the inflow port 107a and is pumped to the outflow port 107b and flows out. Through this series of operations, the piezoelectric pump functions as a positive displacement pump. In the figure, the arrows indicate the direction of liquid flow.

[0006]

However, in the above-described conventional piezoelectric pump, the diaphragm 102 and the housing 101 are sealed by the adhesive 103. Since the adhesive 103 is less elastic than metal, the diaphragm 102 is not sufficiently fixed, and as a result, the displacement of the diaphragm 102 is small and a sufficient discharge flow rate cannot be obtained.

Further, since the diaphragm 102 is a plate-shaped metal, it has a large rigidity to be vertically deformed, and as a result, the displacement of the diaphragm 102 is small and a sufficient discharge flow rate cannot be obtained.

Further, when bubbles or the like enter and stay in the pump chamber 110, the pressure generated by the diaphragm 102 is not transmitted to the fluid and a sufficient discharge flow rate cannot be obtained.

As described above, the conventional piezoelectric pump has a problem that the discharge flow rate is small and a sufficient flow rate cannot be obtained.

Therefore, the present invention solves the above problems, and an object of the present invention is to provide a piezoelectric pump capable of stably obtaining a sufficient discharge flow rate.

[0011]

[Means for Solving the Problems] In order to achieve this object, it has the following constitution.

The invention according to claim 1 of the present invention is
A housing provided with an inlet and an outlet for fluid and an opening;
A diaphragm sealed and fixed in the opening of the housing,
This diaphragm is a piezoelectric pump that drives a diaphragm and that drives the diaphragm, and at least one valve provided inside the housing. The housing and the diaphragm are piezoelectric pumps that are sealed and fixed by welding. Since the sealing and fixing to the body is performed by welding, the diaphragm can be firmly fixed,
Since the displacement of the central part of the diaphragm becomes large, it is possible to obtain the effect that the discharge flow rate can be increased.

The invention according to claim 2 of the present invention is
The piezoelectric pump according to claim 1, wherein the diaphragm and the housing are sealed and fixed by using electric welding. The piezoelectric pump can be welded without applying high heat to the piezoelectric vibrator when the diaphragm is sealed and fixed. Since there is no deterioration, the effect that the discharge flow rate can be increased can be obtained.

The invention according to claim 3 of the present invention is
A housing provided with an inlet and an outlet for fluid and an opening;
A diaphragm sealed and fixed in the opening of the housing,
A piezoelectric vibrator that drives the diaphragm provided on the diaphragm, and at least one valve provided inside the housing, and the diaphragm is a piezoelectric pump that is not a flat plate,
Since the rigidity of the diaphragm as a whole can be reduced, the displacement of the diaphragm is increased and the discharge flow rate can be increased.

The invention according to claim 4 of the present invention is
The diaphragm is the piezoelectric pump according to claim 3, wherein a surface on which the piezoelectric vibrator is provided is convex. The rigidity of the entire diaphragm can be reduced, so that the displacement of the diaphragm can be increased and the discharge flow rate can be increased, and the pump can be realized. Since the volume of the chamber is increased and the amount of fluid in the pump chamber can be increased, the heat capacity is increased and the effect of the change in the outside temperature on the characteristics of the pump can be reduced.

The invention according to claim 5 of the present invention is
The diaphragm is the piezoelectric pump according to claim 3, wherein the surface on which the piezoelectric vibrator is provided is concave. The rigidity of the entire diaphragm can be reduced, so that the displacement of the diaphragm can be increased, the discharge flow rate can be increased, and the size can be reduced. The operation and effect that a thin piezoelectric pump can be realized can be obtained.

The invention according to claim 6 of the present invention is
The diaphragm is the piezoelectric pump according to claim 3, wherein an outer peripheral portion of the piezoelectric vibrator has an uneven shape. Since the rigidity of the entire diaphragm can be reduced, the displacement of the diaphragm can be increased and the discharge flow rate can be increased, and the temperature and the like can be increased. Even if the housing is deformed due to the influence of the stress, the stress is not absorbed by the irregularities on the outer periphery of the piezoelectric vibrator and is not applied to the piezoelectric vibrator, so the characteristics of the piezoelectric vibrator are stable and the reliability improves Is obtained.

The invention according to claim 7 of the present invention is
A housing provided with an inlet and an outlet for fluid and an opening;
A diaphragm sealed and fixed in the opening of the housing,
This diaphragm has a piezoelectric vibrator for driving the diaphragm and at least one valve provided inside the housing, and the inner surface of the pump chamber surrounded by the housing, the diaphragm, and the valve is wettable by a fluid. This is a piezoelectric pump that has been subjected to an improvement treatment, and bubbles are less likely to stay inside the pump chamber, and the pressure from the diaphragm is stably transmitted to the fluid, so that the discharge flow rate is stabilized.

The invention according to claim 8 of the present invention is
The piezoelectric pump according to claim 7, wherein the treatment for improving the wettability with respect to the fluid is mirror polishing, and since the surface energy of the inner surface of the pump chamber can be increased by the mirror polishing, the wettability with respect to the fluid inside the pump chamber is improved. Since the bubbles are less likely to stay inside the pump chamber and the pressure from the diaphragm is stably transmitted to the fluid, the effect of stabilizing the discharge flow rate can be obtained.

The invention according to claim 9 of the present invention is
The piezoelectric pump according to claim 7, wherein the treatment for improving the wettability with respect to the fluid is application of a hydrophilic material. The application of the hydrophilic material improves the wettability with respect to the fluid inside the pump chamber. Since bubbles are less likely to stay inside the pump chamber and the pressure from the diaphragm is stably transmitted to the fluid, the discharge flow rate is stabilized, and the effect of preventing corrosion of the pump chamber by the fluid can be obtained.

The invention according to claim 10 of the present invention is the piezoelectric pump according to claim 7, in which the treatment for improving the wettability with respect to the fluid is UV treatment. Since the surface energy of the inner surface can be increased, the wettability to the fluid inside the pump chamber is improved, bubbles are less likely to stay inside the pump chamber, and the pressure from the diaphragm is stably transmitted to the fluid, so the discharge flow rate is stable. In addition, it is possible to obtain the effect that the stains on the inner surface of the pump chamber due to organic substances can be removed by the UV treatment.

The invention according to claim 11 of the present invention is the piezoelectric pump according to claim 7, wherein the treatment for improving the wettability with respect to the fluid is plasma treatment. Since the surface energy of the inner surface can be increased, the wettability to the fluid inside the pump chamber is improved, bubbles are less likely to stay inside the pump chamber, and the pressure from the diaphragm is stably transmitted to the fluid, so the discharge flow rate is stable. In addition, the effect that dirt on the inner surface of the pump chamber due to organic substances and the like can be removed more strongly than with the UV treatment can be obtained.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) Hereinafter, the first embodiment will be used to particularly describe the claims 1, 2, 3, 4, 7,
The invention described in 8 will be described.

FIG. 1 is a sectional view of a piezoelectric pump according to the first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a housing, which is provided with a fluid inlet 1a, a fluid outlet 1b, a separation wall 1c for separating the fluid inlet 1a and the fluid outlet 1b, and an opening. The opening is sealed with a metal diaphragm 2, the housing 1 and the diaphragm 2 are fixed by a welded portion 3, and one convex surface of the diaphragm 2 has a piezoelectric vibrator 4 having electrodes on both sides. Is pasted. Further, a first valve 5a and a second valve 5b are mounted inside the housing 1 together with a first valve pressing plate 6a and a second valve pressing plate 6b. 7 is a pump room,
The pump chamber 7 includes a housing 1, a diaphragm 2, and a first valve 5
a, the second valve 5b, the first valve holding plate 6a and the second valve holding plate 6b, and the inner surface of the pump chamber 7 is mirror-finished. In FIG. 1, arrows indicate the flowing direction of the liquid.

Next, a method of manufacturing the piezoelectric pump according to the first embodiment of the present invention will be described. First, a stainless plate was pressed, and a convex stamping process was performed with the center portion of about 70% of the diameter being a plane. Further, the surface on the concave side was mirror-polished to manufacture a diaphragm 2. A projection for electric welding was formed on the outer peripheral edge of the diaphragm 2. This projection is a ring-shaped projection having a width of 50 to 200 μm and a height of 50 to 200 μm, and when the diaphragm 2 is sealed and fixed to the housing 1 by electric welding, the projection is melted and the diaphragm 2 and the housing 1 are separated from each other. This is to obtain a good bond.

Subsequently, a disk-shaped piezoelectric vibrator 4 having electrodes formed on both sides of a piezoelectric ceramic was adhered and fixed to the flat surface of the convex portion of the diaphragm 2 with an epoxy adhesive.

On the other hand, stainless steel is cut to provide a liquid inlet 1a, an outlet 1b, a separating wall 1c for separating the inlet 1a and the outlet 1b, and an opening, and the inner wall surface is mirror-polished. The case 1 was produced.

Further, the stainless steel plate is processed into a desired shape and the surface thereof is mirror-polished to form the first valve 5a, the second valve 5b, and the first valve 5a.
The valve retainer plate 6a and the second valve retainer plate 6b were produced.
Subsequently, the first valve 5a, the second valve 5b, the first valve holding plate 6a, and the second valve holding plate 6b were attached and fixed inside the casing 1.

Next, the outer peripheral portion of the diaphragm 2 to which the piezoelectric vibrator 4 is adhesively fixed so as to seal the opening of the casing 1 is brought into contact with the casing 1, and the diaphragm 2 and the casing are formed by electric welding. The body 1 was welded and sealed and fixed. After that, a lead wire (not shown) was connected to one electrode of the piezoelectric vibrator 4 and the diaphragm 2 by soldering to obtain the piezoelectric pump 11 according to the first embodiment of the present invention.

The welding of the diaphragm 2 and the housing 1 may be performed by an arc welding method or the like in addition to the above electric welding method, but the electric welding method is more preferable than the arc welding method or the like. There is an advantage that there is little deterioration due to heat.

Next, the operation of the piezoelectric pump 11 according to the first embodiment of the present invention configured as described above will be described with reference to FIG.

FIG. 2 is a schematic diagram for explaining the operation measurement of the piezoelectric pump according to the first embodiment of the present invention. A cooling device using the piezoelectric pump 10 according to the first embodiment of the present invention is incorporated. It is a schematic diagram of a notebook computer.

In FIG. 2, reference numeral 11 is a piezoelectric pump, 12 is a heat absorber, and 13 is a radiator. The piezoelectric pump 11, the heat absorber 12 and the radiator 13 are connected by a liquid flow path 14, and closed circuit circulation is performed. A cycle is formed, and a liquid of a mixture of water and ethylene glycol is filled in the cycle, and this liquid is used as a refrigerant to form a cooling device. In this cooling device, the heat absorber 12 is brought into close contact with a heating element 16 such as a CPU via a heat transfer pad 16a in the notebook computer main body 15, and the radiator 13
Are stored in the display unit 17.

The operation of the cooling device configured as described above will be described focusing on the piezoelectric pump 11 with reference to FIGS.

When an AC voltage is applied from the power source to the piezoelectric vibrator 4 via the lead wire, the piezoelectric vibrator 4 bends upward.
At this time, first, the open end of the first valve 5a moves upward, and a gap is created between the first valve retainer plate 6a and the first valve 5a.
The liquid refrigerant flowing in from the above flows into the pump chamber 7 through this gap. At this time, the second valve 5b remains closed by the second valve pressing plate 6b existing above. Next, when the piezoelectric vibrator 4 bends downward, the open end of the second valve 5b moves downward,
A gap is created between the valve retainer plate 6b and the second valve 5b, and the liquid refrigerant in the pump chamber 7 flows out from this gap and is pressure-fed from the outlet 1b to the heat absorber 12 side (the arrow in FIG. 1 indicates the liquid refrigerant). Shows the direction of flow).

By continuously bending the piezoelectric vibrator 4 in the vertical direction, the above operation is repeated, and the liquid refrigerant contains the piezoelectric pump 11-heat absorber 12-radiator 13-piezoelectric pump 1.
It circulates in the cooling device formed by the closed circuit circulation cycle of 1. The liquid solvent extruded by the piezoelectric pump 11 is heated by the heating element 16 in the heat absorber 12.
Of the heat is absorbed, moves to the radiator 13, is radiated by the radiator 13, is cooled again, and returns to the piezoelectric pump 11. By repeating this, the heat generated in the notebook computer is released to the outside. This liquid refrigerant has the lowest temperature in the radiator 13 and flows into the piezoelectric pump 11 from the radiator 13 and enters the heat absorber 12
Is leaked to.

Piezoelectric pump 1 according to the first embodiment of the present invention using a notebook computer incorporating the cooling device of FIG.
As a result of performing the operation measurement of No. 1, the conventional piezoelectric pump shown in FIG. 5 has a drive voltage of 40 Vrms and a drive frequency of 50 Hz.
, The discharge flow rate was about 15 cc / min,
With the piezoelectric pump 11 according to the first embodiment of the present invention, the discharge flow rate was increased to about 30 cc / min, and a sufficient cooling capacity could be realized.

As described above, in the piezoelectric pump 11 according to the first embodiment of the present invention, the diaphragm 2 is firmly fixed to the housing 1 by the welding method.
The displacement of the central portion of the diaphragm 2 becomes large, and the diaphragm 2 is processed to have a convex shape.
Since the rigidity of the whole is lowered, the displacement of the diaphragm 2 can be increased and the discharge flow rate can be increased.

Further, since the inner surface of the pump chamber 7 is mirror-polished, the wettability with respect to the liquid refrigerant is improved, bubbles are unlikely to adhere, and the discharge flow rate does not fluctuate and a stable flow rate can be realized.

In the first embodiment, the structure using a single-layer disk-shaped piezoelectric ceramic is described as the piezoelectric vibrator 4, but by using the laminated structure piezoelectric vibrator provided with the internal electrodes. , The same flow rate can be obtained by driving with a lower voltage.

Further, although the piezoelectric ceramic is used as the piezoelectric vibrator 4 in the first embodiment, a similar effect can be obtained by using a piezoelectric single crystal or resin.

In the first embodiment, the diaphragm 2
Although the configuration is described in which the piezoelectric vibrator 4 is bonded to the above, the same effect can be obtained by forming a substance having piezoelectricity on the diaphragm 2 by a method such as sputtering or a sol-gel method.

(Embodiment 2) Hereinafter, the invention according to claims 5 and 9 of the present invention will be described with reference to Embodiment 2.

FIG. 3 is a sectional view of a piezoelectric pump according to the second embodiment of the present invention.

The structure and manufacturing method of the piezoelectric pump according to the second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3, the piezoelectric pump according to the second embodiment of the present invention is different from that according to the first embodiment in the shape of diaphragm 22 and the treatment of the inner surface of pump chamber 27. The manufacturing methods are given the same reference numerals and detailed description thereof is omitted.

First, a stainless plate was press-worked to form a concave shape with a center portion having a diameter of about 70% as a flat surface, and the convex surface was mirror-polished to form a diaphragm 22. Further, a projection for electric welding was formed on the outer peripheral end portion of the diaphragm 22 as in the first embodiment.

Subsequently, the disk-shaped piezoelectric vibrator 4 having electrodes formed on both sides of the piezoelectric ceramic was adhered and fixed to the flat surface of the recess of the diaphragm 22 with an epoxy-based conductive adhesive. Further, an acrylic hydrophilic polymer was applied to the convex surface of the diaphragm 22 which is the inner surface of the pump chamber 27.

On the other hand, as in the first embodiment, stainless steel is cut and mirror-polished to form a housing 1, a stainless plate is processed into a desired shape, and the surface thereof is mirror-polished.
The valve 5a, the second valve 5b, the first valve holding plate 6a, and the second valve holding plate 6b were produced.

Subsequently, these first valve 5a, second valve 5b,
The first valve retainer plate 6a and the second valve retainer plate 6b are attached and fixed to the inside of the casing 1, and the casing 1, the first valve 5a, the second valve 5b, the first valve retainer plate 6a and the An acrylic hydrophilic polymer was applied to the inner surface of each pump chamber 27 of the two-valve retainer plate 6b.

Next, as in the first embodiment, the outer peripheral portion of the diaphragm 22 is brought into contact with the casing so as to seal the opening of the casing 1, and the diaphragm 22 is electrowelded.
And the housing 1 were welded and sealed and fixed. After that, one electrode of the piezoelectric vibrator 4 and the diaphragm 2 are soldered.
A lead wire (not shown) was connected to 2 to obtain the piezoelectric pump 20 according to the second embodiment of the present invention.

As in the first embodiment, the operation of the piezoelectric pump 20 according to the second embodiment of the present invention was measured using a notebook computer incorporating the cooling device shown in FIG. A discharge flow rate of about 25 cc / min was obtained at a frequency of 50 Hz, and a sufficient cooling capacity could be realized.

As described above, the piezoelectric pump 20 according to the second embodiment of the present invention can be made thin as shown in FIG. 3, and the discharge flow rate can be increased.

Further, since the acrylic hydrophilic polymer is applied to the inner surface of the pump chamber 27 to improve the wettability with respect to the liquid refrigerant, bubbles are unlikely to adhere and the discharge flow rate does not fluctuate and a stable flow rate can be realized. .

(Embodiment 3) Hereinafter, the invention of claims 6 and 10 of the present invention will be described with reference to Embodiment 3.

FIG. 4 is a sectional view of a piezoelectric pump according to the third embodiment of the present invention.

The structure and manufacturing method of the piezoelectric pump according to the third embodiment of the present invention will be described with reference to FIG. As shown in FIG. 4, the piezoelectric pump according to the third embodiment of the present invention differs from that of the first embodiment in that the diaphragm 3
Regarding the shape of No. 2 and the treatment of the inner surface of the pump chamber 37, the same configurations and manufacturing methods as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

First, a stainless steel plate was pressed to form a diaphragm 32 by forming concave and convex grooves around the central portion having a diameter of about 70% as a flat surface. In addition, in the outer peripheral end portion of the diaphragm 32, the first embodiment
Similarly to the above, a projection for electric welding was formed.

Subsequently, the disk-shaped piezoelectric vibrator 4 having electrodes formed on both sides of the piezoelectric ceramic was adhered and fixed to the central plane portion of the diaphragm 32 with an epoxy-based conductive adhesive. Further, the pump chamber 37 of the diaphragm 32
After the surface to be the inner surface of (1) was mirror-polished, UV treatment was performed by irradiating ultraviolet light of a high-pressure mercury lamp of 1 kW from a distance of 30 cm for 10 seconds.

On the other hand, as in the first embodiment, stainless steel is cut and mirror-polished to form a housing 1, a stainless plate is processed into a desired shape, and the surface thereof is mirror-polished.
The valve 5a, the second valve 5b, the first valve holding plate 6a, and the second valve holding plate 6b were produced.

Subsequently, these first valve 5a, second valve 5b,
The first valve retainer plate 6a and the second valve retainer plate 6b are attached and fixed to the inside of the casing 1, and the casing 1, the first valve 5a, the second valve 5b, the first valve retainer plate 6a and the On the inner surface of each pump chamber 37 of the two-valve holding plate 6b, the ultraviolet light of the high-pressure mercury lamp of 1 kW was applied from the distance of 30 cm to 1 in the same manner as above.
UV treatment was performed by irradiation for 0 seconds.

Next, as in the first embodiment, the outer peripheral portion of the diaphragm 32 is brought into contact with the housing 1 so as to seal the opening of the housing 1, and the diaphragm 3 is electrowelded.
2 and the housing 1 were welded and sealed and fixed. After that, a lead wire (not shown) was connected to one electrode of the piezoelectric vibrator 4 and the diaphragm 32 by soldering to obtain the piezoelectric pump 30 according to the third embodiment of the present invention.

As in the first embodiment, the operation of the piezoelectric pump 30 according to the third embodiment of the present invention was measured using a notebook computer incorporating the cooling device shown in FIG. A discharge flow rate of about 25 cc / min was obtained at a frequency of 50 Hz, and a sufficient cooling capacity could be realized.

As described above, in the piezoelectric pump 30 according to the third embodiment of the present invention, the discharge flow rate can be increased,
Further, UV treatment is applied to the inner surface of the pump chamber 37 to improve the wettability with respect to the liquid refrigerant, dirt on the inner surface of the pump chamber 37 due to organic substances is removed and bubbles are unlikely to adhere, and a stable flow rate is achieved without fluctuations in the discharge flow rate. did it.

(Fourth Embodiment) Hereinafter, the invention according to claim 11 of the present invention will be described with reference to the fourth embodiment.

The piezoelectric pump according to the fourth embodiment of the present invention is different from that of the third embodiment in the treatment of the inner surface of the pump chamber 37, and the other configurations and manufacturing methods are the same as those in the third embodiment. The description of the same parts will be omitted and will be described with reference to FIG.

As the treatment of the inner surface of the pump chamber 37, plasma treatment was applied instead of the UV treatment of the third embodiment. The plasma treatment is performed on the inner surface of the pump chamber 37 of the diaphragm 32 and the pump chamber 25 of each of the housing 1, the first valve 5a, the second valve 5b, the first valve holding plate 6a, and the second valve holding plate 6b. The inner surface was subjected to plasma irradiation for 1 second by a plasma irradiator ST-7000 manufactured by Keyence Corporation.

Next, as in the third embodiment, the diaphragm 3 plasma-treated so as to seal the opening of the housing 1.
The outer peripheral portion of 2 was brought into contact with the housing 1, and the diaphragm 32 and the housing 1 were welded and sealed and fixed by an electric welding method. After that, a lead wire (not shown) was connected to one electrode of the piezoelectric vibrator 4 and the diaphragm 32 by soldering to obtain the piezoelectric pump 30 according to the fourth embodiment of the present invention.

Similar to the first embodiment, the operation of the piezoelectric pump 30 according to the fourth embodiment of the present invention was measured using a notebook computer incorporating the cooling device shown in FIG. A discharge flow rate of about 25 cc / min was obtained at a frequency of 50 Hz, and a sufficient cooling capacity could be realized.

As described above, in the piezoelectric pump 30 according to the fourth embodiment of the present invention, the discharge flow rate can be increased, and the inner surface of the pump chamber 37 is subjected to the plasma treatment to improve the wettability to the liquid refrigerant. As a result, bubbles did not easily adhere, and the discharge flow rate did not fluctuate and a stable flow rate could be realized. Further, the plasma treatment has an effect that the stains caused by organic substances can be removed more strongly than the UV treatment.

[0071]

As described above, according to the present invention, a housing provided with an inlet and an outlet of a fluid and an opening, a diaphragm sealed and fixed in the opening of the housing, and provided on the diaphragm. A piezoelectric pump that drives the diaphragm and at least one valve provided inside the housing, and the housing and the diaphragm are piezoelectric pumps that are sealed and fixed by welding, and the diaphragm and the housing are sealed. Since the fixing is performed by welding, the diaphragm can be firmly fixed, and the displacement of the central portion of the diaphragm can be increased, so that the discharge flow rate increases.

Further, since the diaphragm is a piezoelectric pump which is not in the form of a flat plate and the rigidity of the entire diaphragm can be made small, the displacement of the diaphragm becomes large and the discharge flow rate can be increased.

Further, the inner surface of the pump chamber surrounded by the casing, the diaphragm and the valve is a piezoelectric pump which has been treated to improve the wettability with respect to the fluid, so that bubbles are less likely to stay inside the pump chamber and Since the pressure is stably transmitted to the fluid, a stable discharge flow rate can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a piezoelectric pump according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining the operation measurement of the piezoelectric pump.

FIG. 3 is a sectional view of a piezoelectric pump according to a second embodiment of the present invention.

FIG. 4 is a sectional view of the piezoelectric pump according to the third and fourth embodiments of the present invention.

FIG. 5 is a sectional view of a conventional piezoelectric pump.

[Explanation of symbols] 1 case 1a Inlet 1b Outlet 1c Separation wall 2,22,32 diaphragm 3 welds 4 Piezoelectric vibrator 5a first valve 5b second valve 6a First valve retainer plate 6b Second valve retainer plate 7, 27, 37 Pump room 11, 20, 30 Piezoelectric pump 12 Heat absorber 13 radiator 14 Liquid flow path 15 laptop computer 16 heating element 16a Heat transfer pad 17 Display

Continued front page    (72) Inventor Yuyuki Okano             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Katsumi Imada             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Atsushi Komatsu             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 3H077 AA02 BB10 CC02 CC09 DD06                       EE01 FF03 FF07 FF08 FF09                       FF36

Claims (11)

[Claims] 1. A housing provided with an inlet and an outlet of a fluid and an opening, a diaphragm sealed and fixed to the opening of the housing, and a piezoelectric vibrator for driving the diaphragm provided in the diaphragm. And a piezoelectric pump having at least one valve provided inside the housing, and the housing and the diaphragm being sealed and fixed by welding. 2. The piezoelectric pump according to claim 1, wherein the welding is electric welding. 3. A housing having a fluid inlet and a fluid outlet and an opening, a diaphragm sealed and fixed to the opening of the housing, and a piezoelectric vibrator for driving the diaphragm provided in the diaphragm. And a at least one valve provided inside the housing, and the diaphragm is configured not to be a flat plate. 4. The piezoelectric pump according to claim 3, wherein the diaphragm has a convex surface on which the piezoelectric vibrator is provided. 5. The piezoelectric pump according to claim 3, wherein the diaphragm has a concave surface on which the piezoelectric vibrator is provided. 6. The piezoelectric pump according to claim 3, wherein the diaphragm has an uneven outer peripheral portion of the piezoelectric vibrator. 7. A housing provided with an inlet and an outlet for fluid and an opening, a diaphragm sealed and fixed to the opening of the housing, and a piezoelectric vibrator for driving the diaphragm provided in the diaphragm. And a at least one valve provided inside the housing, and a piezoelectric pump having a process of improving wettability with a fluid on an inner surface of a pump chamber surrounded by the housing, the diaphragm and the valve. 8. The piezoelectric pump according to claim 7, wherein the treatment for improving the wettability with respect to the fluid is mirror polishing. 9. The piezoelectric pump according to claim 7, wherein the treatment for improving the wettability with respect to the fluid is application of a hydrophilic material. 10. The piezoelectric pump according to claim 7, wherein the treatment for improving the wettability with respect to the fluid is UV treatment. 11. The piezoelectric pump according to claim 7, wherein the treatment for improving the wettability with respect to the fluid is plasma treatment.