WO2005012729A1

WO2005012729A1 - Diaphragm pump and cooling system with the diaphragm pump

Info

Publication number: WO2005012729A1
Application number: PCT/JP2004/010339
Authority: WO
Inventors: Mitsuru Yamamoto; Yasuhiro Sasaki; Atsushi Ochi; Sakae Kitajo
Original assignee: Nec Corporation
Priority date: 2003-08-04
Filing date: 2004-07-21
Publication date: 2005-02-10
Also published as: TW200508489A; CN1833105A; US20070065308A1; JPWO2005012729A1; CN100510400C; TWI255886B

Abstract

A diaphragm pump enabling an increase in pump efficiency by reducing the pressure loss of liquid and a reduction in thickness. The flow passage of the piezoelectric pump (1) comprises a pressure chamber (50) formed in a flat shape in cross section and a suction side flow passages (70a) and a discharge side flow passage (70b) disposed at both ends thereof. The suction side flow passage (70a) and the discharge side flow passage (70b) are disposed at both ends of the pressure chamber (50) so that the axes thereof are aligned with each other. Also, a suction valve (20a) and a discharge valve (20b) are disposed in the suction side flow passage (70a) and the discharge side flow passage (70b). Both the suction valve (20a) and the discharge valve (20b) are installed to tilt relative to the flow direction of the liquid.

Description

Details <

TECHNICAL FIELD The present invention relates to a diaphragm pump and a cooling system provided with the diaphragm and the pump.

The present invention relates to a diaphragm pump used for a cooling system or the like, and more particularly, to a thin diaphragm pump capable of efficiently discharging a liquid. Further, the present invention relates to a cooling system that includes a pump and is used for cooling electronic equipment, for example.

[0002] With higher performance and higher processing speed of electronic devices, power consumption of electronic components such as CPUs is increasing more and more. As a result, the amount of heat generated by the electronic components also increases, and efficiently dissipating the heat generated in the electronic devices due to the power generated by the electronic components is an essential technology from the viewpoint of guaranteeing the operation of the electronic devices.

[0003] As a cooling means of a portable personal computer such as a notebook personal computer, for example, a water-cooled cooling system that performs cooling by circulating liquid by a pump has been proposed instead of an air-cooled cooling system ( For example, see JP-A-2002-232232). Such a water-cooled cooling system includes a flow path having a closed circuit structure that is configured to be in thermal contact with a heat-generating component such as an electronic component, and a pump that circulates liquid in the flow path. In this cooling system, the liquid heated by the heat of the heat-generating component is circulated through the pump to radiate heat, thereby cooling the heat-generating component.

[0004] As a pump of such a cooling system, a piezoelectric pump, which is a kind of a diaphragm pump, can be generated in a small size and can generate a high discharge pressure. The piezoelectric pump usually has a pressure chamber provided with a suction port and a discharge port, a piezoelectric vibrator provided on a wall surface of the pressure chamber, and a flow path communicating with the suction port and the discharge port, respectively. Here, the piezoelectric vibrator functions as a diaphragm (diaphragm) of the diaphragm pump. A piezoelectric vibrator includes an elastic plate made of metal or the like and a piezoelectric element bonded to the elastic plate. When a voltage is applied to the piezoelectric element, the elastic plate (piezoelectric vibrator itself) bends and displaces. In a piezoelectric pump, the pressure acting on the liquid is increased by vibrating the piezoelectric vibrator. Occurs in the pressure chamber. Further, the suction port and the discharge port are provided with a check valve for preventing the liquid from flowing backward and restricting the flow direction of the liquid from the suction port side to the discharge port side.

FIG. 10 shows an example of a conventional piezoelectric pump. The piezoelectric pump 100 shown in FIG. 10 includes a piezoelectric vibrator 130 arranged to form the upper surface of the pressure chamber 150. On the lower surface of the pressure chamber 150, a suction port 121a for sucking a liquid and a discharge port 121b for discharging the liquid are provided. A suction-side flow path 170a for supplying a liquid to the suction port 121a is formed below the pressure chamber 150, and communicates with the suction port 121a. Further, a discharge-side flow path 170b, which is a flow path of the liquid discharged from the discharge port 121b, is formed below the pressure chamber 150, and communicates with the discharge port 121b. Thus, the liquid flow path in the piezoelectric pump 100 is formed from the suction side flow path 170a to the discharge side flow path 170b via the suction port 121a, the pressure chamber 150, and the discharge port 121b in this order. .

[0006] The suction port 121a and the discharge port 121b are provided with a suction valve 120a and a discharge valve 120b, respectively. The suction valve 120a and the discharge valve 120b are made of, for example, an elastic member such as silicone rubber, and control opening and closing of the suction port 121a and the discharge port 121b, respectively.

[0007] The piezoelectric pump 100 configured as described above operates as follows. When the piezoelectric vibrator 130 is displaced upward and the volume in the pressure chamber 150 increases, the pressure in the pressure chamber 150 becomes negative. As a result, the suction valve 120a is opened, and the liquid is supplied from the suction side flow path 170a into the pressure chamber 150. At this time, the liquid does not flow back into the pressure chamber 150 from the discharge-side channel 170b due to the operation of the discharge valve 120b. Next, the piezoelectric vibrator 130 is displaced in the opposite direction, and the volume of the pressure chamber 150 is reduced. Then, since the pressure in the pressure chamber 150 increases, the discharge valve 120b opens, and the liquid is discharged toward the discharge-side flow path 170b. At this time, since the suction valve 120a operates, the liquid does not flow out of the pressure chamber 150 toward the suction-side flow path 170a. The piezoelectric pump 100 functions as a pump by repeating the above operation, and can flow the liquid in one direction.

[0008] However, in the conventional pump, a liquid flow path which is connected to the discharge side flow path from the suction side flow path via the pressure chamber is formed to be bent. For example, in the piezoelectric pump 100 of FIG. 10, the suction side flow path 170a and the discharge side flow path 170b are formed below the pressure chamber 150, and the suction port 121a and the discharge port To communicate with 120b Yes. Therefore, when the piezoelectric pump 100 is operated and the liquid flows along the flow path, the flow direction of the liquid is bent when flowing into the pressure chamber 150 from the suction side flow path 170a. Further, the liquid that has passed through the pressure chamber 150 bends again when flowing out of the pressure chamber 150 into the discharge-side channel 170b. Thus, when the flow of the liquid changes abruptly, the pressure of the liquid is greatly lost. As a result, the flow rate of the liquid passing through the flow path decreases, and as a result, the pump efficiency decreases. A decrease in pump efficiency means a decrease in cooling efficiency in the cooling system.

[0009] Further, in the piezoelectric pump 100, a suction port 121a, a discharge port 121b, and respective flow paths 170a, 170b are located on the lower surface of the pressure chamber 150. Therefore, the total thickness of the pressure chamber 150 and the thicknesses of the flow passages 170a and 170b is substantially the thickness of the pump. Since the pump is mounted on an electronic device such as a portable personal computer, it is desirable that the pump is configured to be thin to make the electronic device thin.

Disclosure of the invention

[0010] Therefore, an object of the present invention is to provide a diaphragm pump that reduces the pressure loss of a liquid, improves the pump efficiency, and realizes a reduction in thickness. It is another object of the present invention to provide a cooling system having such a diaphragm pump and improved cooling efficiency.

[0011] In order to achieve the above object, a diaphragm pump of the present invention has a side surface of a pressure chamber formed so as to be flat and filled with a liquid such that the axes of the pressure chamber are the same as each other. And the suction-side flow path and the discharge-side flow path communicating with the pressure chamber, and the suction-side flow path and the discharge-side flow path, at least one of which is inclined with respect to the axial direction. And a diaphragm disposed on at least one of an upper surface and a lower surface of the pressure chamber, and vibrating to change the volume of the pressure chamber.

According to the present invention, the suction-side flow path and the discharge-side flow path are arranged on the side surface of the pressure chamber so as to sandwich the pressure chamber, and communicate with the pressure chamber. The suction side flow path and the discharge side flow path extend in the same direction so that their axes are the same. Therefore, the flow path of the pump composed of the flow paths and the pressure chambers is straight without bending, so that the pressure loss of the liquid is reduced. It is suppressed and the liquid flows efficiently. Further, since the check valve disposed in the flow path is provided to be inclined with respect to the axial direction of the flow path, that is, the flow direction of the liquid, the pressure loss of the liquid can be further suppressed. At the same time, the pressure chamber is formed flat, and the suction-side flow path and the discharge-side flow path are arranged at both ends of the pressure chamber as described above, so that the entire pump is reduced in thickness. The diaphragm force is applied to at least one of the upper surface and the lower surface of the pressure chamber and acts on one surface of the flat pressure chamber, which is a large area, so that the vibration of the diaphragm is efficiently transmitted to the pressure chamber. Therefore, the drive source can be reduced in size and labor can be saved, and the pump can be reduced in size.

[0013] Each flow path may be configured such that its axis is located at the center of the cross-sectional shape of the pressure chamber in a plane orthogonal to the axis. As a result, the flow of the liquid in the pressure chamber becomes uniform around the axis. In such a configuration, since the axis of the flow path passes through substantially the center of the pressure chamber, the space in the pressure chamber is substantially symmetrical with respect to the axis. Therefore, the flow path of the liquid is also substantially symmetrical with respect to the axis, and the pressure loss of the liquid in the pressure chamber is reduced.

[0014] Each channel and pressure chamber may be formed in a substantially rectangular cross section. In this case, they can be formed by, for example, cutting, and the production is easy. In particular, if the lower surfaces of the flow paths and the pressure chambers are formed on the same surface, the production is easy. In addition, since the flow path is flattened, the liquid circulates efficiently. Here, in order to further suppress the pressure loss of the liquid, the length of the pressure chamber as viewed from the top side in the direction perpendicular to the axis is continuously reduced toward the suction-side flow path or the discharge-side flow path. It may be formed so that it becomes. Further, the pressure chamber may be formed so that the height thereof is continuously reduced toward the suction-side flow path or the discharge-side flow path. In any case, the pressure loss of the liquid in the pressure chamber is reduced by the configuration in which the cross-sectional area of the pressure chamber decreases continuously toward each flow path.

[0015] In the diaphragm pump of the present invention, at least one groove formed on the peripheral wall of the pressure chamber and accelerating the flow of the liquid toward the downstream side in the flow direction may be formed. The groove may have an upper surface opening facing the pressure chamber and into which the liquid flows, and a side opening opening in the peripheral wall surface of the pressure chamber and discharging the liquid downstream in the flow direction. Good. Further, the groove may extend in the radial direction with one point located near the entrance of the discharge-side flow path as a center. By providing such a groove, when the pressure chamber is pressurized by the diaphragm, the liquid is discharged toward the downstream side from the side opening of the groove, and the flow of the liquid is accelerated.

[0016] The diaphragm pump has at least one inlet opening to the upper surface of the suction-side flow path for introducing bubbles mixed in the liquid, and a closed space communicating with the inlet and collecting the introduced bubbles. May further have. Further, the inlet may be provided in the suction side flow path and upstream of the check valve. By providing such a bubble collecting means, the bubbles mixed into the liquid are collected, and the intrusion of the bubbles into the pressure chamber is prevented. In this way, the pressure loss of the liquid is further suppressed by eliminating the bubbles from the flow path or the pressure chamber. By arranging the intake port on the upstream side of the valve in the suction-side flow path, the intrusion of bubbles into the pressure chamber is effectively prevented.

[0017] The diaphragm pump may be a so-called piezoelectric pump whose driving source is a piezoelectric element. Piezoelectric elements are effective in reducing the size and thickness of a pump.

Further, the present invention may be used in a cooling system having a closed-path flow path that circulates the liquid discharged from the discharge-side flow path of the diaphragm and returns it to the suction-side flow path as described above. It is possible. Such a cooling system efficiently cools an object. In particular, a cooling system provided with a pump provided with a bubble collecting means efficiently circulates the liquid for a long period of time because bubbles in the flow path are collected.

[0019] In this specification, a "flat" pressure chamber refers to the maximum length in the axial direction of the pressure chamber when the length in the height direction of the pressure chamber is viewed from the upper surface side, and the direction perpendicular to the axis. Means a pressure chamber with a shape shorter than 1/2 of the maximum length of the pressure chamber.

According to the present invention, by devising the structure of the diaphragm pump, the pressure loss of the liquid can be reduced, the pump efficiency can be improved, and the pump can be made thinner. Further, by providing such a diaphragm pump, it is possible to improve the cooling efficiency of the cooling system and to achieve a reduction in thickness.

Brief Description of Drawings

FIG. 1 schematically shows a cooling system including a piezoelectric pump according to a first embodiment of the present invention. FIG. 1 (a) is a plan view showing a liquid passage in the cooling system, and FIG. 1 (b) is a cross-sectional view taken along line XX of FIG. 1 (a).

FIG. 2 shows a piezoelectric pump according to a first embodiment, wherein FIG. 2 (a) is a cross-sectional view, and FIG. 2 (b) is a vertical cross-sectional view as viewed from above.

FIG. 3 shows a piezoelectric pump according to a second embodiment, in which FIG. 3 (a) is a cross-sectional view, and FIG. 3 (b) is a vertical cross-sectional view as viewed from above.

FIG. 4 is an enlarged perspective view showing one return groove and a flow direction of a liquid.

FIG. 5 is a partially enlarged view showing a modification of the shape of the return groove.

FIG. 6 is a cross-sectional view showing a modification of the pressure chamber shape.

FIG. 7 is a diagram showing an example of a piezoelectric pump according to a third embodiment.

FIG. 8 is a view showing another example of the piezoelectric pump according to the third embodiment.

FIG. 9 is a view showing still another example of the piezoelectric pump according to the third embodiment.

FIG. 10 is a sectional view showing an example of a conventional piezoelectric pump.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)

FIG. 1 is a diagram schematically illustrating a cooling system including a piezoelectric pump according to a first embodiment of the present invention. FIG. 1A is a plan view illustrating a liquid path in the cooling system, and FIG. (b) is a cross-sectional view taken along line X-X in FIG. 1 (a).

[0024] The cooling system 10 shown in Fig. 1 is a water-cooled cooling device that is suitably used for cooling electronic components such as portable personal computers. The cooling system 10 roughly includes a channel unit 60 in which a circulation channel 60a is formed, and a piezoelectric pump 1 connected to the channel unit 60 and circulating the liquid in the channel. The passage unit 60 and the piezoelectric pump 1 form a passage having a closed circuit structure. In addition, this channel is filled with the liquid to be circulated.

[0025] In the passage unit 60, a circulation passage 60a is formed in a predetermined pattern. The cross-sectional shape of the circulation channel 60a is not particularly limited, and may be a rectangular cross-section or a circular cross-section. In the case of the flat channel unit 60 as in the present embodiment, the circulation channel 60a is Preferably, it has a rectangular cross section. Since the cross-sectional shape of the flat flow path unit 60 is a shape in which plate members are overlapped, the circulation flow path 60a has a rectangular cross section, for example, a groove is formed in one plate member, and the other is formed with a groove. The circulation channel 60a is easily formed by joining with the plate member. The piezoelectric pump 1 is connected to both ends of the circulation channel 60a to form one closed channel in cooperation with the circulation channel 60a. The cooling system 10 circulates the liquid in the circulation flow channel 60a by operating the piezoelectric pump 1, and radiates the liquid heated by the heat-generating components.

Hereinafter, the piezoelectric pump 1 will be described in detail with reference to FIG. FIG. 2 shows a piezoelectric pump according to the first embodiment. FIG. 2 (a) is a cross-sectional view, and FIG. 2 (b) is a vertical cross-sectional view as viewed from above.

[0027] The piezoelectric pump 1 has a pressure chamber 50 part of which is formed by the piezoelectric vibrator 30, and a suction port 21a and a discharge port 21b communicating with the pressure chamber 50, respectively. In addition, a suction valve 20a and a discharge valve 20b are provided near the suction port 21a and the discharge port 21b, respectively. When the piezoelectric vibrator 30 vibrates, a pressure change occurs in the pressure chamber 50, and the liquid flows from the suction port 21a to the discharge port 21b in the direction of the arrow in the drawing.

[0028] The pressure chamber 50 is formed between the lower plate 11 and the upper plate 12, which are the housing of the piezoelectric pump 1. Its shape is rectangular and the bottom is flat. At one end of the pressure chamber 50, a suction port 21a through which liquid flows is formed, and at the other end, a discharge port 21b through which liquid flows is formed. Both the suction port 21a and the discharge port 21b are located on the longitudinal center line of the rectangular pressure chamber 50 when viewed from above.

[0029] The suction-side flow path 70a connected to the circulation flow path 60a in Fig. 1 is formed so as to communicate with the suction port 21a, and the discharge-side flow path 70b also connected to the circulation flow path 60a is connected to the discharge port 21b. It is formed to communicate with The suction-side flow path 70a and the discharge-side flow path 70b are arranged in a line on the center line with the pressure chamber 50 therebetween, and extend in the same direction. The suction-side flow path 70a and the discharge-side flow path 70b are both formed in the same shape, and have a rectangular cross section. As described above, if the flow paths 70a and 70b have a rectangular cross section, they can be easily formed by cutting or punching.

[0030] The height of the pressure chamber 50 is substantially the same as the height of the suction-side flow path 70a. Also, the pressure The flow path in the electric pump 1 is formed flat because the lower surface of the pressure chamber 50 and the lower surfaces of the suction side flow path 70a and the discharge side flow path 70b are located in the same plane. I have.

[0031] The piezoelectric vibrator 30 prepared as a diaphragm by bonding two piezoelectric elements (not shown) with a vibrating plate (not shown) sandwiched therebetween acts on the upper surface of the flat pressure chamber 50. Are located. Further, an electrode (not shown) for applying a voltage to the piezoelectric element is formed. By applying an AC voltage to the piezoelectric vibrator 30 configured as described above, the piezoelectric vibrator 30 bends and vibrates in the plate thickness direction.

As the piezoelectric element, for example, a dinoleconic acid / lead titanate-based ceramic material may be used. Various means can be used for bonding the diaphragm and the piezoelectric element depending on the material of the diaphragm. For example, if ceramics or silicon is used for the diaphragm, the piezoelectric element can be integrally formed on the diaphragm by a printing and firing method, a sputtering method, a sol-gel method, a chemical vapor method, or the like. In the present embodiment, a force driving source using a piezoelectric element as a driving source for vibrating the diaphragm is not particularly limited as long as the driving source vibrates the diaphragm.

[0033] In the suction side flow path 70a and the discharge side flow path 70b, a suction valve 20a and a discharge valve 20b made of a thin metal plate such as aluminum are provided, respectively. The valves 20a and 20b are arranged so as to obliquely intersect the flow direction of the liquid. In each of the valves 20a and 20b, the end on the upstream side in the flow direction is supported in a cantilever shape, and the end on the downstream side is a free end that abuts against the side wall of the flow passages 70a and 70b without load. It has become. Therefore, the suction valve 20a opens the suction side flow passage 70a when a negative pressure is generated in the pressure chamber 50, and closes the flow passage 70a when a positive pressure is generated in the pressure chamber 50. On the other hand, the discharge valve 20b closes the passage 70b when a negative pressure is generated in the pressure chamber 50, and closes the passage 70b when a positive pressure is generated.

[0034] The cross-sectional shape of the suction-side flow path 70a and the discharge-side flow path 70b may be a so-called D-cut shape in which a circle or a part of a circle is cut out with a straight line, as in the present embodiment. The valves 20a and 20b can be formed in a simple shape by making the channels 70a and 7Ob have a rectangular cross section. In addition, the attachment can be performed by a relatively easy method, as described above, by attaching one end of the valve member to one wall surface in the flow path. The operation of the piezoelectric pump 1 configured as described above will be described below.

First, a voltage of a predetermined polarity is applied to the piezoelectric vibrator 30, and the piezoelectric vibrator 30 is displaced so as to project upward in the figure. Then, the volume of the pressure chamber 50 increases, and the pressure in the pressure chamber 50 becomes a negative pressure. As a result, the suction valve 20a is displaced to open the suction port 21a, and the liquid flows into the pressure chamber 50 via the suction-side flow path 70a and the suction port 21a. At this time, the discharge valve 20b is in a state of closing the discharge port 20b, and the liquid does not flow out of the discharge port 21b.

Next, a voltage having a polarity opposite to that described above is applied to the piezoelectric vibrator 30 to displace the piezoelectric vibrator 30 so as to project downward in the figure. Thereby, the volume of the pressure chamber 50 is reduced. Then, the discharge valve 20b is displaced, the discharge port 21b is opened, and the liquid is discharged from the discharge-side flow path 70b. At this time, since the suction valve 20a blocks the suction-side flow path 70a, there is no inflow and discharge of liquid from the suction port 21a.

[0038] By repeating the above operation, the suction of the liquid from the suction port 21a and the discharge of the liquid from the discharge port 21b are alternately repeated, and the liquid can be pulsated. Therefore, the liquid circulates in the direction of the arrow in the circulation flow channel 60a shown in FIG.

In the present embodiment, the flow path of the piezoelectric pump 1 is formed flat without bending in the thickness direction of the piezoelectric pump. Specifically, the suction-side flow path 70a, the pressure chamber 50, and the discharge-side flow path 70b are all formed on the lower plate 11. Further, the suction side flow path 70a and the discharge side flow path 70b are located on a straight line with the pressure chamber 50 therebetween, and extend in the same direction. As a result, the flow path of the piezoelectric pump 1 is formed flat and linear. Therefore, as compared with a conventional piezoelectric pump in which the flow path is bent, the pressure loss due to a change in the flow direction of the liquid is suppressed in the piezoelectric pump 1, and the liquid is circulated efficiently. S power In the piezoelectric pump 1, the suction valve 20a and the discharge valve 20b are provided so as to be inclined with respect to the liquid flow direction. Therefore, the suction valve 20a and the discharge valve 20b are displaced by a small force as compared with a valve provided so as to be orthogonal to the flow direction, and the pressure loss of the liquid can be further reduced. From the above, the pump efficiency of the piezoelectric pump 1 is improved as compared with the conventional one, and accordingly, the cooling efficiency of the cooling system 10 (see FIG. 1) is improved. In this embodiment, any one of the suction valve 20a and the discharge valve 20b is used. Although each of them is inclined with respect to the flow direction, at least one of them may be inclined.

In the present embodiment, since the flow paths 70a and 70b are located at both ends of the pressure chamber 50 as described above, the flow paths are flattened, and the overall thickness of the piezoelectric pump 1 is reduced. I have. Further, since the piezoelectric vibrator 30 is disposed so as to act on one surface of a large area of the pressure chamber 50 formed in a flat rectangular parallelepiped shape, the bending displacement of the piezoelectric vibrator 30 is efficiently performed in the pressure chamber 50. Is transmitted to. Therefore, a sufficient flow rate can be obtained with the relatively small piezoelectric vibrator 30, and as a result, the size of the piezoelectric pump 1 can be reduced. Note that, in the present embodiment, the number and shape of the force piezoelectric vibrators in which only one piezoelectric vibrator 30 is disposed on the upper surface of the pressure chamber 50 are not particularly limited. For example, two pressure vibrators are provided on the upper and lower surfaces of the pressure chamber 50.

[0041] As described above, the cooling system 1 using the piezoelectric pump 1 that achieves a reduction in thickness and an improvement in pump efficiency can circulate liquid efficiently. Further, for example, if a heat-generating component is arranged directly in the flow channel unit 60 or in the vicinity of the flow channel unit 60, the heat generated by the component is efficiently radiated.

(Second Embodiment)

In the first embodiment, the pressure chamber is formed in a rectangular parallelepiped shape, but may be formed so that the cross-sectional area of the pressure chamber changes gradually in order to reduce the resistance of the liquid.

FIG. 3 shows a piezoelectric pump according to a second embodiment of the present invention. The piezoelectric pump 2 shown in FIG. 3 is formed so that the pressure chamber 50 'has a streamline shape. Further, a structure (return groove 1 la) for accelerating the flow of the liquid is provided on the peripheral wall of the pressure chamber 50 '. The other structures are the same as those of the piezoelectric pump 1 of FIG. 2, and the structural parts having the same functions are denoted by the same reference numerals as in FIG. 2, and the description thereof is omitted.

As shown in FIG. 3B, the pressure chamber 50 ′ of the present embodiment is formed with a peripheral wall surface ie that has a substantially streamline shape when viewed from the upper surface side. The peripheral wall lie is provided perpendicular to the bottom 1 lb of the pressure chamber 50 '. Further, the peripheral wall surface is continuous with the suction port 21a and the discharge port 21b, respectively, and is bent outward in an arc shape. Note that this arc-shaped shape is It is preferable to appropriately set the resistance according to the type of the liquid, the characteristics of the piezoelectric vibrator 30, and the like so that the resistance of the piezoelectric vibrator 30 is minimized.

[0045] A plurality of return grooves 11a are formed on the peripheral wall of the pressure chamber 50 'so as to open to the peripheral wall surface lee. In the present embodiment, the five return grooves 11a are formed at a predetermined interval from each other and have the same groove width. Each return groove 11a is formed so as to extend in the radiation direction about one point (not shown) located near the discharge port 21b. That is, the return groove 11a is arranged so that its opening faces the above-mentioned one point near the discharge port 21b. Preferably, the one point is located at the center of the discharge port 21b.

A more detailed shape of the return groove 11a will be described below with reference to FIG. FIG. 4 is an enlarged perspective view showing the flow direction of the liquid around one return groove 11a and its periphery. As shown in FIG. 4, the return groove 11a is opened on the edge upper surface 11c, which is the upper surface of the peripheral wall, and on the peripheral wall surface ie. Further, the depth of the return groove 11a is formed so as to gradually increase toward the tip (the peripheral wall side).

[0047] A protrusion lid having a predetermined height with respect to the edge upper surface 11c is formed on the outer peripheral side of the edge upper surface 11c. In the present embodiment, the piezoelectric vibrator 30 (see FIG. 3A) is disposed on the upper surface of the convex portion lid. Therefore, a predetermined gap is formed between the edge upper surface 11c and the piezoelectric vibrator 30, and the gap also forms a part of the pressure chamber 50 '. In such a configuration, when the piezoelectric vibrator 30 is displaced so as to protrude downward, the liquid flows in from the opening on the upper surface side of the return groove 11a, passes through the return groove 11a, and passes through the peripheral wall surface. From the side opening.

[0048] In the piezoelectric pump 2 configured as described above, the peripheral wall surface ie of the pressure chamber 50 'is formed in a streamline shape, and cuts toward the suction side flow path 70a and the discharge side flow path 70b. The area is continuously decreasing. As a result, the resistance between the liquid and the peripheral wall surface is reduced, and the pressure loss of the liquid in the pressure chamber 50 'becomes smaller. Further, when the piezoelectric vibrator 30 is displaced to discharge the liquid from the discharge-side channel 70b (see FIG. 3), the liquid in the return groove 11a is discharged toward the discharge port 21b. Therefore, the flow of the liquid in the pressure chamber 50 'is accelerated, and the pump efficiency of the piezoelectric pump 2 is further improved. In particular, since each return groove 1 la opens toward the discharge port 21b, the liquid discharged from the return groove 11a is more Effectively accelerate liquid flow.

It is preferable that the number and shape of the return grooves 11a, the height of the protrusions lid, and the like are appropriately set according to the type of liquid, the shape of the discharge port 20b, and the like. For example, depending on the shape of the pressure chamber and the position of the discharge port, only one return groove 11a may be formed. However, in the case of the pressure chamber 50 ′ formed symmetrically with respect to the axis of the flow paths 70a and 70b as in the present embodiment, as shown in FIG. 3B, the return groove 11a is formed with the axis interposed therebetween. It is provided to be symmetrical. As a result, the liquid flows in substantially the same manner across the axis.

[0050] For example, as shown in Fig. 5, the shape of the return groove 11a 'is such that the width of the return groove 1la' is tapered toward the pressure chamber 50 'and the liquid in the return groove 11a' is tapered. It may be possible to discharge at a higher speed from the tip of the. Thereby, the flow of the liquid is further accelerated, and the pump efficiency is further improved.

Further, in the piezoelectric pump 2 of FIG. 3, the height of the pressure chamber 50 ′ is kept constant, and the length force in the direction orthogonal to the axis of the channels 70 a and 70 b is continuous toward the channels 70 a and 70 b. The peripheral wall is curved so as to be shorter, and the cross-sectional area of the pressure chamber 50 ′ becomes smaller toward the inlet 21a and the outlet 21b. However, the shape of the pressure chamber is not limited to this as long as the cross-sectional area is continuously reduced.

For example, as shown in FIG. 6, the pressure chamber 50 ″ may be provided with a taper 12 a at a corner thereof. That is, the cross-sectional area may be configured to decrease as the height of the pressure chamber 50 ″ continuously decreases toward the suction port 21 a or the discharge port 21 b. Thereby, the resistance of the liquid passing through the pressure chamber 50 "" is reduced, and the pressure loss of the liquid is suppressed.

(Third Embodiment)

In general, a closed channel such as the cooling system 10 shown in FIG. 1 is filled with a liquid so that no bubbles remain. However, bubbles may be mixed into the liquid due to, for example, dissolved oxygen in the liquid becoming bubbles. In a piezoelectric pump, the presence of bubbles in the flow path causes a reduction in pump efficiency. In addition, the presence of bubbles in the flow path having the closed circuit structure leads to a decrease in the cooling efficiency of the cooling system 10. Therefore, in order to further improve the pump efficiency, in addition to the configurations of the above two embodiments, the piezoelectric pump may be provided with a unit for collecting bubbles mixed in the liquid.

[0055] Each of the piezoelectric pumps 3, 3 ', 3 "' shown in Figs. 7 to 9 has a gas chamber 35, 35 ', 35"' as means for collecting bubbles. FIGS. 7 (a) to 9 (a) are cross-sectional views of the piezoelectric pumps 3, 3 ′ and 3 ″, respectively, and FIGS. 7 (b) and 9 (b) are gas chambers 35 and 3 respectively. 35 is a vertical sectional view showing the inside of FIG.

In the piezoelectric pump 3 shown in FIG. 7, a gas chamber 35 is formed above the piezoelectric vibrator 30.

The other structure is the same as that of the piezoelectric pump 1 of FIG. 2, and the structural portions having the same functions are denoted by the same reference numerals as those of FIG. 2, and the description thereof is omitted.

The gas chamber 35 is formed by a housing of the piezoelectric pump 3 so as to cover the piezoelectric vibrator 30 and the suction-side flow path 70a and the discharge-side flow path 70b.

Further, one intake port 35a for introducing bubbles into the gas chamber 35 is provided slightly upstream of the suction valve 20a. The intake port 35a is formed as a hole communicating the suction side flow path 70a and the gas chamber 35, and is located on the upper surface of the suction side flow path 70a.

When such a piezoelectric pump 3 is applied to, for example, the cooling system 10 shown in FIG. 1, a flow path of a closed structure is formed by the flow path of the cooling system 10 and the air pressure chamber 35. Then, the flow path is completely filled with the liquid to be circulated. That is, in the initial state of the cooling system 10, the inside of the gas chamber 35 is also filled with the liquid.

In the cooling system 10 thus configured, when bubbles are generated in the liquid, the bubbles move in the circulation channel 60 (see FIG. 1) by the flow of the liquid. Then, the air bubbles that have moved along the upper wall of the suction-side flow path 70a are taken into the intake port 35a and float upward. At the same time, the liquid in the gas chamber 35 is thereby pushed out of the inlet 35a, and bubbles are collected in the gas chamber 35. In this way, in the piezoelectric pump 3, air bubbles can be eliminated from the flow path of the cooling system 10, and the power S can be circulated without lowering the pump efficiency.

[0061] In the present embodiment, as shown in Fig. 7 (b), the opening of the intake 35a is formed in a circular shape. The shape of the suction port 35a is not limited to a shape that can collect air bubbles. For example, one long hole (not shown) extending in the width direction of the suction-side flow path 70a. (Shown). Thus, bubbles moving along the upper wall of the flow channel 70a can be effectively collected. If the number of inlets is set to two or more, when the bubbles enter the gas chamber 35 from one of the inlets, the liquid flows out from the other inlet at the same time. Thus, the exchange operation force between the bubble and the liquid may be smoothly performed. In addition, of course, the inlet 35 may be arranged at a higher position with respect to the flow path 70a in order to make the collection of air bubbles more effective, or a groove or a notch for guiding the air bubbles to the inlet 35 may be provided. May be formed.

[0062] In addition, the piezoelectric pump according to the third embodiment may be variously modified as shown in Figs. The piezoelectric pump 3 ′ shown in FIG. 8 has the piezoelectric vibrator 30 arranged on the lower surface of the pressure chamber 50. The piezoelectric pump 3 ′ ″ in FIG. 9 has a gas chamber 35 ″ arranged in an annular region. The gas chambers 35, 35 ', 35', which are essentially different from the piezoelectric pump 3 in the piezoelectric pumps 3 ', 3' ', have the same function.

[0063] As described above, in the third embodiment, the piezoelectric pump 3 is provided with the gas chamber 35 so as to be able to collect bubbles generated in the liquid. The pump efficiency is further improved. Further, the cooling efficiency of the cooling system 10 is maintained high for a long time. In the cooling system 10 including the piezoelectric pumps 3, 3 ', and 3' '' described in the present embodiment, even if the liquid expands due to a change in environmental temperature or the like, the volume change does not occur in the gas chambers 35, 35 ', and 35. Absorbed by ''. Therefore, breakage of the piezoelectric pumps 3, 3 ', 3' '' and the flow path of the cooling system 10 is prevented.

Although the exemplary embodiments have been described above, the components described in each embodiment may be used in any combination as much as possible.

Claims

The scope of the claims

[1] a pressure chamber formed flat and filled with a liquid,

A suction-side flow path and a discharge-side flow path that are respectively arranged on the side surfaces of the pressure chamber so that the axes of the pressure chambers are the same, and communicate with the pressure chamber;

A check valve disposed in each of the suction-side flow path and the discharge-side flow path, at least one of which is inclined with respect to the axial direction;

A diaphragm disposed on at least one of an upper surface and a lower surface of the pressure chamber, the diaphragm being oscillated to change the volume of the pressure chamber.

2. The diaphragm pump according to claim 1, wherein the axis is located at a center of a cross-sectional shape of the pressure chamber on a plane orthogonal to the axis.

3. The cross-sectional shape of each of the pressure chamber, the suction-side flow path, and the discharge-side flow path in a plane orthogonal to the axis is all substantially rectangular. Diaphragm pump.

4. The diaphragm pump according to claim 3, wherein a lower surface of the pressure chamber and lower surfaces of the suction-side flow path and the discharge-side flow path are formed on the same plane.

[5] The length of the pressure chamber in a direction perpendicular to the axis as viewed from the upper surface side is formed so as to be continuously reduced toward the suction-side flow path or the discharge-side flow path. The diaphragm pump according to claim 1, wherein the diaphragm pump is any one of claims 1 to 4.

6. The pressure chamber according to claim 1, wherein a height of the pressure chamber is formed so as to continuously decrease toward the suction-side flow path or the discharge-side flow path. Shear force, diaphragm pump described in item 1.

7. The diaphragm pump according to claim 1, further comprising at least one groove formed on a peripheral wall of the pressure chamber to accelerate the flow of the liquid toward a downstream side in the flow direction.

[8] The groove has an upper surface opening facing the pressure chamber and into which the liquid flows, and a side opening opening in the peripheral wall surface of the pressure chamber and discharging the liquid toward the downstream side in the flow direction. 8. The diaphragm pump according to claim 7, comprising:

[9] The groove has a radiation direction centered on a point located near the entrance of the discharge-side flow path. 9. The diaphragm pump according to claim 7, wherein the diaphragm pump extends.

[10] At least one inlet for opening the upper surface of the suction-side flow path for introducing bubbles mixed in the liquid, and a seal communicating with the inlet and collecting the introduced bubbles. 10. The diaphragm pump according to claim 1, further comprising a space.

[11] The inlet is located in the suction side flow path and upstream of the check valve.

The diaphragm pump according to claim 10.

12. The diaphragm pump according to claim 1, wherein the diaphragm is a piezoelectric vibrator driven by a piezoelectric element.

[13] The diaphragm pump according to any one of claims 1 to 12, and

A flow path having a closed circuit structure for circulating the liquid discharged from the discharge side flow path of the diaphragm pump and returning the liquid to the suction side flow path.