JP5104097B2 - Fluid transfer device - Google Patents

Description

  The present invention relates to a fluid transfer device, for example, a fluid transfer device using a piezoelectric element that bends and deforms.

  Piezoelectric pumps are used for cooling water transportation pumps for small electronic devices such as notebook computers and fuel transportation pumps for fuel cells. Also, a piezoelectric pump can be used as a blower pump in place of a cooling fan such as a CPU or a blower pump for supplying oxygen necessary for power generation by a fuel cell. A piezoelectric pump is a pump that uses a piezoelectric element that bends and deforms when a voltage is applied, and has an advantage of a simple structure, a thin configuration, and low power consumption.

  Patent Document 1 discloses a single fan blade piezoelectric fan that generates an axial air flow with a low profile. The piezoelectric fan includes a fan blade attached to only one end inside the housing. A piezoelectric element is fixed to the fan blade, and the fan blade is bent by the piezoelectric element. As the fan blades bend, an axial air flow is generated through an internal cavity formed in the housing.

  Patent Document 2 discloses a piezoelectric motor having a simple structure and high efficiency. This piezoelectric motor includes a stator in which a parallelogram constant elastic body is sandwiched between two piezoelectric ceramics, and a cylindrical rotor in contact with one side of the parallelogram of the stator, and the rotor serves as a rotating shaft of the impeller. Yes. When the parallelogram piezoelectric ceramic is driven, the longitudinal vibration and the bending vibration are combined to generate a circular motion or an elliptical motion on one side of the parallelogram, and the rotor is rotated by the vibration.

  However, in both cases of Patent Documents 1 and 2, the discharge port and the suction port are always in communication, and air is leaked from the discharge side to the suction side, so that backflow occurs or the discharge pressure is low. There are drawbacks. Moreover, since parts such as a fan blade and a rotor are required in addition to the piezoelectric element, there is a drawback that the structure becomes large.

In Patent Document 3, a plurality of piezo elements are arranged in a plane and spaced in the circumferential direction, the individual piezo elements are electrically connected, and these piezo elements are integrally formed of a non-conductive flexible material. A pump piezo vibrator is disclosed in which a mold is provided and a check hole is provided in the center of the mold part and a check valve is provided to allow fluid to flow only in one direction through the hole. However, in the case of this structure, a plurality of individually manufactured piezo elements must be integrally molded, so that the overall size becomes large, and when a voltage is applied to each piezo element, the central portion is on one side. Since it only vibrates in the plate thickness direction between the protruding state and the protruding state, the check valve is necessary to transfer the fluid. Therefore, there is a problem that the structure becomes complicated. Further, since the piezo element reciprocates in the thickness direction, there is a problem that pulsation occurs and a continuous fluid flow cannot be generated.
Special Table 2000-513070 JP 2004-289880 A Japanese Utility Model Publication No. 61-130783

  Therefore, an object of the present invention is to provide a fluid transfer device that can transfer a fluid without a check valve and has a simple structure and a small size.

In order to achieve the above object, the present invention provides a fluid transfer device including a substrate and a hollow disk-shaped piezoelectric element that is displaceably disposed on the substrate, and the piezoelectric element includes the piezoelectric element. The outer peripheral part of the diaphragm that is attached to the upper surface of the central part of the larger and elastically deformable diaphragm and extends to the outer peripheral side from the piezoelectric element is fixed to the substrate, and the piezoelectric element is circumferentially attached to the piezoelectric element. A plurality of divided electrodes are formed, and voltage applying means for sequentially applying voltages having different phases in the circumferential direction is provided to the divided electrodes, and voltages having different phases sequentially being applied to the divided electrodes in the circumferential direction. Thus, the piezoelectric element is bent and deformed in the circumferential direction in a wavy manner, and the centrifugal force generated by moving the pocket chamber communicating from the central part to the outer peripheral part between the diaphragm and the substrate in the circumferential direction is obtained. the using center Providing a fluid transfer device, characterized in that the transfer fluid in the Luo outer circumferential direction.

  The present invention utilizes the principle of a centrifugal fan to transfer fluid by centrifugal force from the center of a piezoelectric element toward the outer periphery. That is, a hollow disk-shaped piezoelectric element having a plurality of divided electrodes divided in the circumferential direction is arranged on a substrate. In a state where no voltage is applied to the piezoelectric element, the substrate and the piezoelectric element are in contact with each other with almost no gap, so that the gap between the inlet and the outlet is closed. When a voltage whose phase is sequentially shifted in the circumferential direction is applied to the divided electrodes, the piezoelectric element is wavyly bent in the circumferential direction. For this reason, a pocket chamber is generated between the piezoelectric element and the substrate, and this pocket chamber rotates at a high speed. Therefore, the centrifugal force generates a fluid flow from the center of the piezoelectric element toward the outer periphery. Unlike the conventional reciprocating pump, this fluid flow has almost no pulsation, so that the fluid can be smoothly and continuously transferred. Since the flow path (pocket chamber) is conducted from the central portion to the outer peripheral portion between the piezoelectric element and the substrate, a large flow rate can be obtained as compared with the positive displacement pump. Further, according to the present invention, since the periphery of the portion other than the flow path (pocket chamber) portion where the fluid formed from the inflow port to the discharge port flows is sealed by the piezoelectric element and the substrate, from the discharge side to the inflow side. Fluid does not leak easily. Thereby, a pressure can be maintained high and the backflow from the periphery can be reduced. Since the pocket chamber containing the fluid can be sealed by the piezoelectric element itself, there is little fluid leakage, the fluid in the pocket chamber can be reliably transferred, and a high discharge pressure can be generated. Since only a plurality of divided electrodes are formed on one piezoelectric element, the structure is simple, and it can be configured to be small and thin.

  The fluid that can be transferred by the fluid transfer device of the present invention may be a liquid or a gas (for example, air). In particular, when the piezoelectric element is driven at a high frequency, it is preferable to use gas. In the case of air, it can be used for applications such as a blower for cooling a semiconductor element and a blower for evaporating water generated at the air electrode of a fuel cell.

  According to a preferred embodiment, the plurality of divided electrodes are divided at an equal angle in the circumferential direction of the hollow disk-shaped piezoelectric element, and when the piezoelectric element is bent and deformed, the position around the entire circumference is determined. The phase difference is 4π + 2nπ (n = 0, 1, 2,...), And the phase difference is preferably equally distributed to a plurality of divided electrodes divided at equal angles. In this case, since the deformation of the piezoelectric element is an axially symmetric deformation, the piezoelectric element is not inclined with the driving. Further, since the displacement difference between the convex deformation portion and the concave deformation portion is maintained substantially constant with driving, it is possible to support such that the center of gravity of the entire piezoelectric element hardly moves, and vibration is suppressed.

  According to a preferred embodiment, the piezoelectric element is affixed to the upper surface of the central part of the diaphragm that is larger than the piezoelectric element and is elastically deformable, and the outer peripheral part of the diaphragm extending outward from the piezoelectric element is fixed to the substrate. It is good to have the structure. Although it is possible to place the piezoelectric element directly on the substrate, when the piezoelectric element is bent and deformed so as to have a radial ridgeline, the outer periphery and inner periphery of the piezoelectric element can be fixed to the substrate. Therefore, it is difficult to stably hold the piezoelectric element. On the other hand, if the piezoelectric element is affixed on an elastically deformable diaphragm and the outer periphery of the diaphragm is fixed to the substrate, the piezoelectric element can be stably attached to the substrate while allowing deformation of the piezoelectric element. . The diaphragm may be a thin metal plate or a resin plate.

  According to a preferred embodiment, a fluid inlet is formed at the center of one of the substrate and the diaphragm, and the outer periphery of either the substrate or the diaphragm is fixed to the substrate and the diaphragm. It is preferable to form a fluid outlet at a position inside the portion. In the case of a structure in which the piezoelectric element is attached onto the diaphragm as described above and the outer periphery of the diaphragm is fixed to the substrate, a fluid inlet is formed at the center of either the substrate or the diaphragm, By forming the fluid outlet in the outer periphery of either the substrate or the diaphragm, there is no need to provide holes in the piezoelectric element, and the piezoelectric element can be efficiently deformed.

  As the piezoelectric element, a laminated piezoelectric element having a bimorph structure may be used, or a piezoelectric element having a single plate structure may be used. In the case of a piezoelectric element having a multilayer structure, a plurality of divided electrodes and non-divided full-surface electrodes may be alternately stacked with a piezoelectric layer interposed therebetween, or a plurality of first divided electrodes, A plurality of second divided electrodes provided with a phase shift with respect to the first divided electrodes may be alternately stacked with piezoelectric layers therebetween. In the former case, since one electrode can be a solid electrode (entire electrode), only one type of electrode pattern is required. In the latter case, the number of polarization electrodes per surface can be reduced compared to the former, and there is an advantage that the voltage applied to each divided electrode can be lowered. In the case of a piezoelectric element having a single plate structure, the piezoelectric element itself does not bend and deform. Therefore, it may be attached to a vibration plate such as a metal plate to form a unimorph structure.

  In the above description, the piezoelectric element is disposed so as to be displaceable with respect to the fixed substrate. However, a piezoelectric element may be used as the substrate. That is, two disk-shaped piezoelectric elements may be arranged to face each other, and these piezoelectric elements may be bent and displaced symmetrically. In this case, since the volume of the pocket chamber is doubled, not only the fluid discharge pressure but also the discharge flow rate can be increased. Note that the fluid transfer device may be configured with only two piezoelectric elements, but the fluid transfer device is configured by attaching each piezoelectric element to the diaphragm and bonding the outer peripheral portions of these diaphragms together. Is good.

  As described above, according to the present invention, a hollow disk-shaped piezoelectric element in which a plurality of divided electrodes are formed in the circumferential direction is arranged on a substrate, and voltages having different phases are sequentially applied to the divided electrodes in the circumferential direction. As a result, the piezoelectric element undergoes a wave-like bending deformation in the circumferential direction. And since the pocket chamber produced | generated between a piezoelectric element and a board | substrate rotates to the circumferential direction, a fluid is transferred to an outer peripheral direction from a center part with a centrifugal force, Therefore A fluid can be transferred continuously with few pulsations. By adjusting the frequency applied to the piezoelectric element, a centrifugal force corresponding to the properties of the fluid can be obtained, and the flow rate can be increased. In addition, since the fluid transfer device is composed of one disk-shaped piezoelectric element and a substrate and does not require a check valve, the structure is simplified, and the size and thickness can be reduced. Furthermore, since the piezoelectric element has a flat plate shape when not driven and the flow path between the inlet and the outlet is closed, fluid leakage when not driven can be eliminated.

  Hereinafter, preferred embodiments of the present invention will be described based on examples.

  1 to 3 show a first embodiment of a fluid transfer device according to the present invention, and here, an example in which it is used as a micro blower for air supply is shown. 1 is an overall perspective view of the micro-blower A of the present embodiment, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a sectional view taken along line III-III in FIG.

  The micro blower A of the present embodiment includes a substrate 10 that is a fixed plate, a disc-shaped diaphragm 20 that is displaceably disposed thereon, and a hollow disc-like shape that is attached to the upper surface of the diaphragm 20 ( And an annular) piezoelectric element 30. The entire outer periphery of the diaphragm 20 is fixed to the substrate 10 with an adhesive 11 (indicated by hatching in FIG. 2). In addition, it may be fixed by caulking, welding, screwing, brazing or the like instead of adhesion. The substrate 10 and the diaphragm 20 are made of discs having the same diameter, and the piezoelectric element 30 is set to have a smaller diameter than the diaphragm 20. The substrate 10 is made of a rigid metal plate, a resin plate, or the like, and is made of a plate material having a flat upper surface in contact with the vibration plate 20. A plurality of outflow ports 12 are formed in a portion of the substrate 10 on the inner diameter side slightly from the outer peripheral portion where the adhesive 11 is applied. In this embodiment, the outlet 12 is formed by a plurality of arc-shaped slit holes, but it may be a single hole, and the shape is not limited to the slit shape but may be a round hole. The vibration plate 20 is made of a metal plate or resin sheet that is thinner than the substrate 10 and is preferably an elastic body that can be deformed following the bending deformation of the piezoelectric element 30. An inflow hole 21 is formed at the center of the diaphragm 20. Note that the inlet 21 may be provided at the center of the substrate 10. The outer diameter dimension of the piezoelectric element 30 is smaller than the application area of the adhesive 11 so that the displacement of the piezoelectric element 30 is not restrained by the adhesive 11. In this embodiment, the outer peripheral edge of the piezoelectric element 30 is located on the inner diameter side from the outflow port 12, but may be located on the outer diameter side from the outflow port 12. An opening 34 having a diameter larger than that of the inflow hole 21 of the diaphragm 20 is formed at the center of the piezoelectric element 30.

  4 and 5 show the sectional structure of the piezoelectric element 30 and its electrode structure. As shown in FIGS. 4 and 5, the piezoelectric element 30 is formed by laminating two piezoelectric layers 31a and 31b with the entire surface electrode 32 therebetween, and the two piezoelectric layers 31a and 31b are indicated by an arrow P. As shown in the figure, the entire region is polarized in the same direction. Divided electrodes 33a to 33h are formed on the main surfaces of the front and back sides and are divided into eight in the circumferential direction through a narrow gap portion. The divided electrodes 33a to 33h are formed at a 45 ° pitch. Of the eight divided electrodes 33a to 33h, the divided electrodes at diagonal positions are connected to each other, and the divided electrodes facing each other are connected to each other and connected to the voltage applying means 1. For this reason, in FIG. 5, the voltage E1 is applied to the divided electrodes 33a and 33e, the voltage E2 is applied to the divided electrodes 33b and 33f, the voltage E3 is applied to the divided electrodes 33c and 33g, and the divided electrode 33d. And the voltage E4 is applied to 33h. The full surface electrode 32 is connected to the ground, that is, 0v.

  FIG. 6 shows an example of deformation when a voltage is applied to one region 30 a divided into eight pieces of the piezoelectric element 30. When a voltage in one direction is applied between the divided electrode and the entire surface electrode, the electrode is deformed so as to have a ridge line in the upward direction and in the radial direction (radial direction) as shown in FIG. 6 (b), when a reverse voltage is applied, it is deformed to have a ridge line in the downward direction and in the radial direction (radial direction) as shown in FIG. 6 (c). Thus, since each part of the piezoelectric element 30 is driven as a bimorph, the diaphragm 20 to which the piezoelectric element 30 is attached also deforms following the piezoelectric element 30. The piezoelectric element 30 is not necessarily limited to the laminated bimorph structure, and a single-plate piezoelectric element in which a divided electrode pattern as shown in FIG. The unimorph structure may be used.

  FIG. 7 shows the amplitudes and phases of the voltages E1 to E4 applied from the voltage applying means 1 to the divided electrodes. As is apparent from FIG. 7, sinusoidal voltages E1 to E4 having a phase of π / 2 and an equal amplitude are applied to each divided electrode. By applying a sinusoidal electric field whose phase is advanced by π / 2 to the adjacent divided electrode, the same electric field is applied to the regions at the diagonal positions of the piezoelectric element 30, and the same deformation is caused in those regions. Is realized.

  FIG. 8 shows the displacement direction of each region at a certain moment when a voltage is applied to the piezoelectric element as shown in FIGS. 5 and 7 by +, 0, and −. If the + direction is the front surface direction, the-direction is the back direction. When two regions at the diagonal position are bent to the maximum in the + direction, the two regions orthogonal to the two regions are bent to the maximum in the-direction, and the four regions therebetween are deformed so as to neutralize the deformation in both directions. . Such deformation occurs continuously while circling.

  As shown in FIG. 2, when the diaphragm 20 with the piezoelectric element 30 attached is combined with the substrate 10, the diaphragm 20 deforms following the piezoelectric element 30, so that the diaphragm 20 and the substrate 10 are diagonal. The substrate 10 and the diaphragm 20 are separated most greatly in a direction perpendicular to the two, and a pocket chamber S (see FIG. 3B) is formed. When the phase of the applied voltage is changed, the contact location is rotated, and when the phase of the applied voltage is changed by 2π rad, the contact location is rotated by π rad. When the angular velocity of the applied voltage is increased and the rotational angular velocity of the contact portion is increased, the air sandwiched between the pocket chambers S between the substrate 10 and the diaphragm 20 is moved from the center toward the outer periphery by centrifugal force. It begins to flow. Therefore, the fluid can be sucked from the inlet 21 provided at the center of the diaphragm 20 and discharged from the outlet 12 provided at the outer peripheral portion of the substrate 10. Unlike the conventional pump of the reciprocating drive type, this flow hardly generates pulsation and can generate a continuous flow. In addition, since the number of divided electrodes is eight and the phase difference between adjacent electrodes is π / 2, the substrate 10 is always in contact at two diagonal positions, and no tilt occurs with driving. In addition, since the center of gravity of the entire piezoelectric element hardly moves, stable air blowing performance can be achieved as a centrifugal fan. When the piezoelectric element 30 is elastically held on the substrate 10 by the diaphragm 20 as in the above embodiment, the piezoelectric element 30 may tilt even if the number of divided electrodes and the voltage phase are not set as described above. Absent.

  In the above embodiment, since the number of divided electrodes is eight, the region bent to the maximum in the + direction at a certain moment and the region bent to the maximum in the-direction are orthogonal to each other, but depending on the number of divided electrodes, However, the region bent to the maximum in the + direction and the region bent to the maximum in the-direction do not necessarily exist at the orthogonal positions. In addition, although the number of divided electrodes is eight, for example, when the number of divided electrodes is twelve and the phase difference between adjacent electrodes is π / 2, the substrate 10 is contacted at three locations in the circumferential direction. The element 30 can be deformed in a more stable posture. The number of divided electrodes can be increased arbitrarily. For example, when the phase difference between adjacent electrodes is π / 2, the number of divided electrodes is preferably a multiple of 4 (8 or more).

  FIG. 9 shows a second embodiment of the present invention. In this embodiment, unlike the first embodiment, two different patterns are used as the divided electrodes of the piezoelectric element 30. That is, as shown in FIG. 9A, the first divided electrode patterns 35a to 35d divided at a 90 ° pitch and the first divided electrode patterns 35a to 35d divided at a 90 ° pitch as shown in FIG. Second divided electrode patterns 36a to 36d provided with a phase shifted by π / 4 with respect to one divided electrode pattern are alternately stacked with piezoelectric layers interposed therebetween. In FIG. 9, e1 to e4 indicate voltages applied to the divided electrodes.

  FIG. 10 shows the amplitudes and phases of the voltages e1 to e4 applied to the divided electrodes. As shown in FIG. 10, sinusoidal voltages e1 to e4 having a phase of π / 2 and an equal amplitude are applied to the divided electrodes, and thus the piezoelectric element 30 is displaced similarly to the first embodiment. In the first embodiment, voltages E1 to E4 having phases shifted by π / 2 are applied between the divided electrodes 33a to 33e and the entire surface electrode 32 (0v), but in the second embodiment, the piezoelectric layer is sandwiched. Since the voltages e1 to e4 whose phases are shifted by π / 2 are applied between the opposed divided electrodes, the amplitudes of the voltages e1 to e4 can be made lower than the voltages E1 to E4. In addition, the number of divided electrodes formed on one surface is smaller than that of the first embodiment, in other words, the number of gap portions partitioning the divided electrodes can be reduced, so that the piezoelectric element 30 can be bent effectively. .

  FIG. 11 shows a piezoelectric micro blower B according to a third embodiment of the present invention. In the first and second embodiments, the example in which the piezoelectric elements are arranged opposite to each other on the substrate which is a fixed flat plate is shown. However, in this embodiment, two piezoelectric elements 40 and 50 are arranged to face each other. It is. In this example, the piezoelectric elements 40 and 50 are attached on the vibration plates 41 and 51, respectively, and the outer peripheral portions of the vibration plates 41 and 51 are bonded to each other. When an inflow hole 42 is provided in the center of one diaphragm 41 and an outflow hole 52 is provided in the outer periphery of the other diaphragm 51, fluid is sucked from the center on the front side of the piezoelectric microblower B, and Fluid can be discharged from the peripheral part. In this case, by applying a voltage so that the opposing portions of the pair of piezoelectric elements 40 and 50 are displaced symmetrically, the volume of the pocket portion holding the fluid is doubled compared to the case where a fixed plate is used. Therefore, there is an advantage that the flow rate is increased.

In the above embodiment, the piezoelectric element attached to the vibration plate is disposed on the substrate. However, the vibration plate may be omitted and disposed directly on the substrate. However, in that case, it is necessary to hold the piezoelectric element by some pressurizing means so that the piezoelectric element does not move on the substrate.
In the above embodiment, the structure in which two piezoelectric layers are stacked as the piezoelectric element has been described. However, a structure in which three or more piezoelectric layers are stacked may be used. When a large number of thin layers are laminated, the applied voltage can be further lowered.
Also, the laminated structure may be a single-layered piezoelectric body fired, electrodes formed on the front and back surfaces, and then adhered to each other, or a plurality of ceramic green sheets on which electrodes are formed are laminated, and then It may be fired. In the case of a laminated structure, the polarization directions of the laminated piezoelectric layers are not limited to the same direction, but may be polarized in an appropriate direction so that each bent region is driven as a bimorph.
In the above embodiment, the fluid transfer device is used as a microblower for transferring a compressible fluid such as air. However, the present invention can also be applied to an incompressible fluid such as a liquid.

1 is an overall perspective view of a piezoelectric micro blower according to a first embodiment of the present invention. It is a disassembled perspective view of the piezoelectric micro blower shown in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1 and a cross-sectional view taken along line III-III during driving. It is a cross section of the piezoelectric element used for the piezoelectric micro blower shown in FIG. It is an electrode pattern and wiring diagram of the piezoelectric element shown in FIG. It is a figure which shows the bending deformation of one area | region of the piezoelectric element shown in FIG. It is a figure which shows the phase of each voltage applied to the piezoelectric element shown in FIG. It is a top view which shows the displacement direction of each area | region of the piezoelectric element shown in FIG. It is a figure which shows 2nd Example of the electrode pattern of a piezoelectric element. It is a figure which shows the phase of each voltage applied to the piezoelectric element shown in FIG. It is sectional drawing of 3rd Example of a piezoelectric element.

Explanation of symbols

A, B Piezoelectric micro blower 1 Voltage application means 10 Substrate (fixed plate)
DESCRIPTION OF SYMBOLS 11 Adhesion part 12 Outflow port 20 Diaphragm 21 Inflow port 30 Piezoelectric element 31a, 31b Piezoelectric layer 32 Whole surface electrode 33a-33h Split electrode 35a-35d, 36a-36d Split electrode

Claims (6)

A fluid transfer device comprising a substrate and a hollow disk-shaped piezoelectric element disposed on the substrate so as to be displaceable,
The piezoelectric element is affixed to the upper surface of the central portion of a diaphragm that is larger and elastically deformable than the piezoelectric element, and the outer peripheral portion of the diaphragm that extends outward from the piezoelectric element is fixed to the substrate.
The piezoelectric element is formed with a plurality of divided electrodes divided in the circumferential direction,
Voltage application means for sequentially applying voltages having different phases in the circumferential direction to the divided electrodes is provided,
By sequentially applying voltages having different phases in the circumferential direction to the divided electrodes, the piezoelectric element is bent and deformed in a wavy shape in the circumferential direction, and from the central part to the outer peripheral part generated between the diaphragm and the substrate. by moving the pocket chamber which communicates with the circumferential direction, the fluid transfer device, characterized in that the transfer fluid in the outer peripheral direction from the central portion by utilizing the centrifugal force.   The plurality of divided electrodes are divided at equal angles in the circumferential direction of the hollow disk-shaped piezoelectric element. When the piezoelectric element is bent and deformed, the phase difference in the entire circumference is 4π + 2nπ (n = 2. The fluid transfer device according to claim 1, wherein the phase difference is equally distributed to a plurality of divided electrodes divided at equal angles. A fluid inflow port is formed at a central portion of one of the substrate and the diaphragm, and is an outer peripheral portion of one of the substrate and the diaphragm and at a position inside the fixing portion between the substrate and the diaphragm. the fluid transfer device according to claim 1 or 2, characterized in that the outlet of the fluid is formed. The piezoelectric element, and a whole surface electrode is not divided and divided plurality of divided electrodes, any one of claims 1 to 3, characterized in that is obtained by laminating alternately to between the piezoelectric layers 1 The fluid transfer device according to item.   The piezoelectric element includes a plurality of divided first divided electrodes and a plurality of second divided electrodes that are divided and provided with a phase shifted with respect to the first divided electrodes. The fluid transfer device according to any one of claims 1 to 3, wherein the fluid transfer devices are alternately stacked. The substrate includes the piezoelectric element and the diaphragm, and sequentially applies voltages having different phases in the circumferential direction to the divided electrodes so that the opposed divided electrodes of the pair of piezoelectric elements have the same phase. The fluid is transferred from the central portion to the outer peripheral direction by bending and deforming the pair of piezoelectric elements and moving a pocket chamber generated between the pair of piezoelectric elements in the circumferential direction. 6. The fluid transfer device according to any one of items 5 to 5 .

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