JP6809818B2 - Piezoelectric actuator - Google Patents

Description

The present invention relates to a piezoelectric actuator used in, for example, a mass flow controller, a precision positioning device for an XY table, or the like.

The piezoelectric actuator includes a laminated piezoelectric element and a metal case containing the laminated piezoelectric element so that the upper and lower ends of the laminated piezoelectric element abut on the inner wall, and the metal case hits the lower end of the laminated piezoelectric element. It includes a contacted substrate and a cylinder bonded to the upper surface of the substrate (see, for example, Patent Document 1). Here, the tubular body has a tubular portion extending vertically and a flange portion connected to the lower end of the tubular portion. For example, with a compressive load applied to the laminated piezoelectric element, the tubular body and the substrate It is manufactured by joining the collar with laser welding or resistance welding.

Japanese Unexamined Patent Publication No. 11-22845

In the above-mentioned piezoelectric actuator, the heat generated when welding the base and the flange portion may be transferred to the joint portion between the laminated piezoelectric element and the base portion, and the joint portion may be cracked due to thermal stress. It was.

Further, if this crack grows due to long-term driving, the load applied to the laminated piezoelectric element becomes a one-sided state, and if it further grows, the applied load may decrease and the desired displacement amount may not be stably obtained. there were.

The present invention has been devised in view of the above problems, and is a piezoelectric actuator that suppresses the occurrence of cracks at the joint between the laminated piezoelectric element and the substrate and can stably obtain a displacement amount for a long period of time. The purpose is to provide.

The piezoelectric actuator of the present disclosure includes a laminated piezoelectric element and a metal case accommodating the laminated piezoelectric element so that the upper and lower ends of the laminated piezoelectric element abut on an inner wall, and the metal case is the laminated. A substrate abutting on the lower end of the mold piezoelectric element and a tubular body joined to the upper surface of the substrate are included, and the tubular body is connected to a tubular portion extending vertically and a lower end of the tubular portion. The substrate has an annular portion, and the substrate and the flange portion are joined at the annular portion, and the laminated piezoelectric element, the tubular body, and the annular portion on the upper surface of the substrate. in a region between the parts, said the multilayer piezoelectric element Ri erected Bugaa as at intervals surrounding the stacked piezoelectric element, the standing portion is positioned away from said cylindrical body It is characterized by being.

According to the piezoelectric actuator of the present disclosure, the occurrence of cracks in the joint portion between the laminated piezoelectric element and the substrate is suppressed, and a stable displacement amount can be realized for a long period of time.

It is a schematic perspective view of one Embodiment of a piezoelectric actuator. It is the schematic cross-sectional view cut along the line AA of the piezoelectric actuator shown in FIG. (A) is an enlarged cross-sectional view of an example of region B shown in FIG. 2, and (b) is a partially omitted plan view of an example of region B shown in FIG. It is a partially omitted schematic perspective view of an example of region B shown in FIG. It is a schematic perspective view of an example of the laminated piezoelectric element shown in FIG. It is a partially omitted plan view of another example of region B shown in FIG. It is a partially omitted plan view of another example of region B shown in FIG. FIG. 5 is an enlarged cross-sectional view of another example of region B shown in FIG. FIG. 5 is an enlarged cross-sectional view of another example of region B shown in FIG. FIG. 5 is an enlarged cross-sectional view of another example of region B shown in FIG.

Hereinafter, an embodiment of the piezoelectric actuator of the present disclosure will be described with reference to the drawings.

1 is a schematic perspective view of an embodiment of the piezoelectric actuator, FIG. 2 is a schematic cross-sectional view taken along the line AA of the piezoelectric actuator shown in FIG. 1, and FIG. 3A is an example of region B shown in FIG. An enlarged cross-sectional view, FIG. 3B is a partially omitted plan view of an example of the region B shown in FIG. 2, FIG. 4 is a partially omitted schematic perspective view of an example of the region B shown in FIG. 2, and FIG. 5 is shown in FIG. It is the schematic perspective view of the example of the laminated type piezoelectric element shown.

The piezoelectric actuator 10 shown in FIGS. 1 to 4 includes a laminated piezoelectric element 1 and a metal case 2 accommodating the laminated piezoelectric element 1 so that the upper and lower ends of the laminated piezoelectric element 1 abut on the inner wall. There is. The metal case 2 includes a base 21 that is in contact with the lower end of the laminated piezoelectric element 1 and a tubular body 22 that is joined to the upper surface of the base 21, and the tubular body 22 is a tubular portion 221 that extends vertically. And a flange portion 222 connected to the lower end of the tubular portion 221. Further, in the region between the laminated piezoelectric element 1 and the tubular body 22 on the upper surface of the substrate 21, there is an upright portion 3 so as to surround the laminated piezoelectric element 1 at a distance from the laminated piezoelectric element 1. ..

As shown in FIG. 5, the laminated piezoelectric element 1 includes, for example, an active portion in which a plurality of piezoelectric layers 11 and internal electrode layers 12 are alternately laminated, and a piezoelectric layer laminated at both ends in the stacking direction of the active portion. It is a laminated piezoelectric element provided with a laminated body 13 having an inactive portion made of 11. Here, the active portion is a portion where the piezoelectric layer expands or contracts in the stacking direction during driving, and the inactive portion is a portion where the piezoelectric layer does not expand or contract in the stacking direction during driving.

The laminated body 13 constituting the laminated piezoelectric element 1 is formed in a rectangular parallelepiped shape having, for example, a length of 4 to 7 mm, a width of 4 to 7 mm, and a height of about 20 to 50 mm. The laminated body 13 may have, for example, a hexagonal column shape or an octagonal column shape.

The plurality of piezoelectric layers 11 constituting the laminated body 13 are made of a piezoelectric porcelain (piezoelectric ceramics) having piezoelectric characteristics, and the pressure electromagnetic device is formed to have an average particle size of, for example, 1.6 to 2.8 μm. .. As the piezoelectric device, for example, a perovskite-type oxide made of lead zirconate titanate (PbZrO _3- PbTIO ₃ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ) and the like can be used.

The plurality of internal electrode layers 12 constituting the laminate 13 are formed of, for example, silver, silver-palladium alloy, silver-platinum, copper, etc., and the positive electrode and the negative electrode (or ground electrode) are each of the laminate 13. It is derived alternately on a pair of opposite sides of the. With this configuration, in the active portion, a driving voltage is applied to the piezoelectric layer 11 sandwiched between the internal electrode layers 12 adjacent to each other in the stacking direction.

The laminated body 13 may include a metal layer or the like that is a layer for relieving stress and does not function as an internal electrode layer.

An external electrode 14 is provided on each of the pair of opposite side surfaces of the laminate 13 from which the positive electrode or the negative electrode (or the ground electrode) of the internal electrode layer 12 is derived, and is electrically connected to the derived internal electrode layer 12. It is connected. The external electrode 14 is a metallized layer made of, for example, a sintered body of silver and glass. As shown in FIG. 3, a lead wire 41 is attached to the external electrode 14 with solder 42, and a drive voltage is applied via the lead wire 41.

On the other hand, both positive and negative electrodes (or ground electrodes) of the internal electrode layer 12 are exposed on the other pair of opposite side surfaces of the laminated body 13, and a coating layer 15 made of an oxide is required on these side surfaces. Is formed. By forming the coating layer 15, it is possible to prevent creepage discharge between both electrodes that occurs when a high voltage is applied during driving. Examples of the oxide forming the coating layer 15 include ceramic materials. In particular, the oxide can follow the drive deformation (expansion and contraction) of the laminate 13 when the piezoelectric actuator 10 is driven, and the coating layer 15 is peeled off to cause creeping discharge. It is preferable that the material is deformable by stress so that it does not occur. Specifically, partially stabilized zirconia, Ln _1-X Si _X AlO _{3 + 0.5X} (Ln is Sn, Y, La, Ce, which can be deformed by locally undergoing phase transformation when stress is generated and changing in volume. A ceramic material such as Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and at least one selected from Yb. X = 0.01 to 0.3). Alternatively, piezoelectric materials such as barium titanate and lead zirconate titanate, in which the distance between ions in the crystal lattice changes so as to relieve the generated stress, can be mentioned. The coating layer 15 is formed by, for example, forming an ink, applying it to the side surface of the laminate 13 by dipping or screen printing, and sintering it.

Further, the piezoelectric actuator 10 includes a metal case 2 containing the laminated piezoelectric element 1 so that the upper and lower ends of the laminated piezoelectric element 1 abut on the inner wall. The metal case 2 includes a base 21, a cylinder 22 having a lower end bonded to the upper surface of the base 21, and a lid 23 joined to the upper end of the cylinder 22. Then, the lower end surface of the laminated piezoelectric element 1 is in contact with the upper surface of the substrate 21, and the upper end surface of the laminated piezoelectric element 1 is in contact with the lower surface of the lid 23.

The base 21, the cylinder 22, and the lid 23 are made of a metal material such as SUS304 or SUS316L.

The tubular body 22 has a tubular portion 221 extending vertically and a flange portion 222 connected to the lower end of the tubular portion 221. The tubular body 22 is formed into a bellows shape by, for example, a seamless pipe having a predetermined shape and then rolling or hydrostatic pressing. The tubular body 22 has a predetermined spring constant so that it can follow the expansion and contraction of the laminated piezoelectric element 1 when a voltage is applied to the laminated piezoelectric element 1, and the spring thereof depends on the thickness, groove shape, and number of grooves. The constant is being adjusted. For example, the thickness of the tubular body 22 is, for example, 0.1 to 0.5 mm. The tubular portion 221 extending vertically from the tubular body 22 to the one end side opening (upper end side opening) is cylindrical, but the other end side opening (lower end side opening) of the tubular body 22 is radially outward. It has a so-called trumpet shape that spreads toward it. As described above, the opening on the other end side of the tubular body 22 has a trumpet shape, so that the tubular body 22 has a flange portion 222.

Further, the substrate 21 has a disk shape, and in the example shown in the figure, the peripheral portion is thinner than the other portions. The peripheral edge of the substrate 21 and the flange 222 of the tubular body 22 are joined by welding, for example, so that a compressive load is applied to the laminated piezoelectric element 1. The substrate 21 is formed with two through holes through which the lead pin 43 can be inserted, and the lead pin 43 electrically connected to the lead wire 41 is inserted through the through hole. Then, for example, soft glass 44 is filled in the gap between the through holes, and the lead pin 43 is fixed.

The outer diameter of the lid 23 is formed to be the same as the inner diameter of the one end side opening of the cylinder 22, and the lid 23 is fitted from the one end side opening of the cylinder 22 to form the one end side opening of the cylinder 22. Its side surface is joined to the inner wall in the vicinity (near the upper end) by, for example, welding.

Then, as shown in FIGS. 2 to 4, the region between the laminated piezoelectric element 1 and the tubular body 22 on the upper surface of the substrate 21 constituting the metal case 2 is spaced from the laminated piezoelectric element 1. There is an upright portion 3 so as to surround the laminated piezoelectric element 1. In other words, the piezoelectric actuator 10 is an upright portion arranged around the laminated piezoelectric element 1 so as not to come into contact with the laminated piezoelectric element 1 at a portion of the upper surface of the substrate 21 located inside the tubular body 22. It has 3.

As a result, a part of the heat generated when the substrate 21 and the flange portion 222 are welded can be released to the upright portion 3 and dissipated from the upright portion 3. Therefore, it is possible to realize a piezoelectric actuator capable of suppressing cracks generated at the joint portion between the laminated piezoelectric element 1 and the substrate 21 and stably obtaining a displacement amount for a long period of time.

Here, as shown in the figure, the upright portion 3 can be provided closer to the tubular body 22 than the laminated piezoelectric element 1. Since the upright portion 3 is provided at a position far from the laminated piezoelectric element 1, it is possible to make it more difficult for heat to be transferred to the joint portion between the laminated piezoelectric element 1 and the substrate 21.

Further, as shown in FIGS. 3 and 4, the erecting portion 3 can be configured to have an annular wall in a plan view that continuously surrounds the laminated piezoelectric element 1 around it. As a result, the heat distribution becomes almost uniform when viewed in the circumferential direction. Therefore, even if stress is applied to the joint portion between the laminated piezoelectric element 1 and the substrate 21, the stress is applied almost evenly. Is less likely to occur where the stress is concentrated.

As shown in FIG. 6, it may be composed of a plurality of thin columnar bodies arranged around the laminated piezoelectric element 1 in the circumferential direction, and as shown in FIG. 7, around the laminated piezoelectric element 1. It may be composed of a plurality of arcuate walls arranged in the circumferential direction in a plan view.

The thickness of the upright portion 3 (width in the radial direction of the substrate 21) is preferably set to, for example, 0.1 to 0.3 mm from the viewpoint of heat distribution and miniaturization.

Further, as shown in the figure, the height of the standing portion 3 can be made higher than the height corresponding to the thickness of the flange portion 222. Small metal particles (scattered matter) may be generated when the base 21 and the flange portion 222 are resistance welded. However, the height of the standing portion 3 is higher than the height of the flange portion 222. Since the particles (scattered matter) can be prevented from flying to the inner laminated piezoelectric element 1, it is possible to prevent the particles (scattered matter) from adhering to the laminated piezoelectric element 1.

The height of the upright portion 3 in this case is preferably set to be, for example, 0.5 to 1.0 mm higher than the thickness of the flange portion 222 from the viewpoint of particle suppression and insertability of the tubular body 22. To.

Further, as shown in FIG. 8, the tubular body 22 may have a shape that is bent at a substantially right angle from the inner surface of the tubular portion 221 to the lower surface of the flange portion 222 when viewed in cross section, but as shown in FIG. In addition, the tubular body 22 has a curved inner surface that gradually expands from the inner surface of the tubular portion 221 to the lower surface of the flange portion 222, and has a space surrounded by the standing portion 3, the base 21, and the tubular body 22. It can also be shaped like a right angle.

Since there is a space between the upright portion 3 and the tubular body 22 (flange portion 222) to store the molten metal generated when the base 21 and the flange portion 222 are resistance welded, this metal is used as the upright portion 3 It is also possible to suppress the particles (scattered matter) from jumping out from the gap between the cylinder 22 and the cylinder 22 and prevent the particles (scattered matter) from flying to the inner laminated piezoelectric element 1.

The term "having a space surrounded by the standing portion 3, the base 21 and the tubular body 22" as used herein means that there may be a gap between the standing portion 3 and the tubular body 22. The width of this gap is preferably, for example, 0.1 to 0.2 mm from the viewpoint of particle suppression and insertability of the tubular body 22.

Further, as shown in FIG. 10, the standing portion 3 may be in contact with the inner surface of the tubular portion 221. By accurately engaging the upright portion 3 on the upper surface of the substrate 21 with the tubular body 22, the upright portion 3 can be formed into a shape in contact with the inner surface of the tubular portion 221. As a result, particles (scattered objects) can be prevented from flying inside the tubular body 22.

Next, a method of manufacturing the piezoelectric actuator 10 according to the present embodiment will be described.

First, a ceramic green sheet to be the piezoelectric layer 11 is produced. Specifically, a ceramic slurry is prepared by mixing a calcined powder of piezoelectric ceramics, a binder made of an organic polymer such as acrylic or butyral, and a plasticizer. Then, a ceramic green sheet is produced from this ceramic slurry by using a tape molding method such as a well-known doctor blade method or a calender roll method. As the piezoelectric ceramic, any ceramic having piezoelectric characteristics may be used, and for example, a perovskite-type oxide composed of PbZrO _3- PbTiO ₃ or the like can be used. Further, as the plasticizer, dibutyl phthalate (DBP), dioctyl phthalate (DOP) and the like can be used.

Next, a conductive paste to be the internal electrode layer 12 is produced. Specifically, a conductive paste is prepared by adding and mixing a binder and a plasticizer to a metal powder of a silver-palladium alloy. This conductive paste is printed on the above-mentioned ceramic green sheet by a screen printing method, and then a plurality of ceramic green sheets on which the conductive paste is printed are laminated and conductive pastes are formed on both ends in the lamination direction. A laminated molded body is obtained by laminating a plurality of unprinted ceramic green sheets. The laminated body 13 is obtained by debindering the laminated molded product at a predetermined temperature and then firing it at 900 to 1200 ° C.

Next, an oxide ink is printed by screen printing on a pair of side surfaces from which both internal electrode layers (positive electrode and negative electrode) are derived from the side surfaces of the laminate 13, and then fired at 900 to 1200 ° C. to form a coating layer. 15 is formed.

In the oxide ink, the oxide powder is dispersed in a solution of a solvent, a dispersant, a plasticizer, and a binder, and then three rolls are passed several times to crush the agglomeration of the powder and at the same time. It is made by dispersing powder.

Next, the external electrode 14 made of the metallized layer is formed. First, a binder is added to silver particles and glass powder to prepare a silver glass-containing conductive paste, and the positive electrode or the negative electrode of the internal electrode layer 12 is printed on a pair of opposite side surfaces of the laminate 13 from which the positive electrode or the negative electrode is derived by a screen printing method. , The baking process is performed at a temperature of about 500 to 800 ° C. As a result, the external electrode 14 made of the metallized layer is formed, and the laminated piezoelectric element 1 is completed.

Next, the external electrode 14 and the lead wire 41 are soldered. Further, a substrate 21 is prepared in which an upright portion 3 and an annular portion (not shown) for resistance welding are formed by cutting, and a through hole is formed by hole processing. The upright portion 3 may be formed by cutting the substrate 21 or by fixing another member (for example, a ring-shaped member).

Next, the lead pin 43 is inserted into each of the two through holes formed in the substrate 21, and the gap is filled with soft glass 44 to fix the substrate 21, and the lower end of the laminated piezoelectric element 1 is adhered to the upper surface of the substrate 21. Adhere with an agent. Then, the lead wire 41 soldered to the external electrode 14 of the laminated piezoelectric element 1 with solder 42 and the lead pin 43 attached to the substrate 21 are connected by soldering.

Next, a bellows shape is formed on the seamless cylindrical cylinder 22 made of SUS304 by rolling. By changing the shape of the mold during rolling, the thickness of the groove and the radius of curvature can be changed. The lid 23 made of SUS304 is welded by laser welding so as to close the opening on one end side (upper end side) of the cylinder 22. A collar portion 222 is formed on the other end side (lower end side) of the tubular body 22.

Here, in order to form a shape that is bent at a right angle when viewed in cross section as shown in FIG. 8, the cylindrical cylinder 22 may be provided with a right angle to the mold shape at the time of rolling. Similarly, in order to obtain a curved shape (trumpet shape) when viewed in cross section as shown in FIG. 9, a curved shape may be provided in the mold shape at the time of rolling.

Next, the tubular body 22 is put on the laminated piezoelectric element 1 bonded to the substrate 21, the tubular body is pulled with a predetermined load, and a load is applied to the laminated piezoelectric element 1. In this state, the flange portion 222 of the tubular body 22 and the base 21 are welded by resistance welding.

Finally, the piezoelectric actuator of the present embodiment is completed by applying a DC electric field of 0.1 to 3 kV / mm to the lead pin 43 attached to the substrate 21 to polarize the laminated body 13.

Then, by connecting the lead pin 43 and the external power source and applying a voltage to the piezoelectric layer 11, each piezoelectric layer 11 can be largely displaced by the inverse piezoelectric effect.

A piezoelectric actuator as an example was manufactured as follows.

First, a ceramic slurry in which a calcined powder of piezoelectric ceramics containing lead zirconate titanate (PbZrO _3- PbTiO ₃ ) having an average particle size of 0.4 μm as a main component, a binder and a plasticizer is mixed is prepared, and a doctor blade method is performed. A ceramic green sheet to be a piezoelectric layer having a thickness of 120 μm was produced.

260 ceramic green sheets printed with a conductive paste as an internal electrode prepared by adding a binder to a silver-palladium alloy (95% by mass of silver-5% by mass of palladium) on one side of this ceramic green sheet by a screen printing method. A laminated molded body was prepared by laminating 20 sheets of ceramic green sheets without conductive paste on the upper and lower layers.

Next, after cutting the laminated molded body with a dicing saw machine so as to have a predetermined size, the laminated molded body was dried and fired to prepare a laminated body. The firing was carried out at 1000 ° C. for 200 minutes after maintaining the temperature at 800 ° C. for 90 minutes. The laminated body had a rectangular parallelepiped shape, and its size was 5 mm in length and 5 mm in width and 35 mm in height.

Next, inks made of partially stabilized zirconia, a piezoelectric material, the same material as the piezoelectric layer, and lead zirconate titanate are prepared, and screen printing is performed so that the thickness of each coating layer is 20 μm. , The inner electrode layer was printed on the side surface of the laminated body in which both electrodes were exposed, and then fired at 1000 ° C. to form a coating layer on the side surface of the laminated body.

Next, a binder is added to silver particles and glass powder to prepare a silver glass-containing conductive paste, which is printed on the side surface of the laminate by a screen printing method and baked at a temperature of about 500 to 800 ° C. to the outside. After forming the electrode, the lead wire was connected to the external electrode by soldering.

Moreover, a disk-shaped substrate was prepared with SUS304. Specifically, a base having a shape shown in FIG. 2 was produced by providing an upright portion and an annular portion to be welded by cutting and forming through holes at two locations. Then, a lead pin was attached to the through hole formed in the substrate with soft glass. The vertical portion had a ring shape with a height of 1.0 mm and a thickness (width in the radial direction of the substrate) of 0.3 mm. The annular portion has a triangular cross section with a height of 0.2 mm and a width of 0.5 mm.

Next, the laminate was fixed to the upper surface of the substrate with an adhesive, and the lead wire soldered to the external electrode and the lead pin attached to the substrate were connected by soldering.

Next, a disk-shaped lid was produced with SUS304.
Further, a SUS316L seamless cylinder having a thickness of 0.15 mm was rolled to produce a cylinder having a bellows shape and a trumpet-shaped lower end portion (flange portion).

The lid was inserted into the prepared cylinder, and the cylinder and lid were welded together. Then, this welded material is put on the laminated piezoelectric element adhered to the substrate, the tubular body is pulled with a predetermined load, a load is applied to the laminated piezoelectric element, and then the tubular body and the annular portion of the substrate are brought into contact with each other. The part was welded by resistance welding.

Finally, a DC electric field of 3 kV / mm was applied to the two lead pins of these samples for 15 minutes to perform polarization treatment, and the piezoelectric actuator of the example was produced.

On the other hand, as a comparative example, a piezoelectric actuator having the same configuration as the above was manufactured except that there was no upright portion.

Then, the displacement amount before and after the durability test was measured by the displacement measuring device for each of the piezoelectric actuators of the examples and the comparative examples.

First, when a DC voltage of 200 V was applied to each piezoelectric actuator to obtain the initial displacement amount, the displacement amount of both the piezoelectric actuators of the examples and the comparative examples was 55 μm.

Further, these piezoelectric actuators were subjected to a durability test in which they were continuously driven at room temperature at a voltage of 200 V for 1000 hours. As a result, the displacement amount of the piezoelectric actuator of the example hardly changed, whereas the displacement amount of the piezoelectric actuator of the comparative example decreased by about 5%.

From this, it was confirmed that the piezoelectric actuator of the example can obtain the displacement amount more stably for a long period of time.

10 ... Piezoelectric actuator 1 ... Piezoelectric element 11 ... Piezoelectric layer 12 ... Internal electrode layer 13 ... Laminated body 14 ... External electrode 15 ... Coating layer 2 ... Metal case 21 ... Base 22 ... Cylindrical body 221 ... Cylindrical portion 222 ... Flange portion 23 ... Lid body 3 ... Standing portion 41 ... Lead wire 42 ... Solder 43 ... Lead pin 44 ... Soft glass

Claims (5)

A laminated piezoelectric element and a metal case accommodating the laminated piezoelectric element so that the upper and lower ends of the laminated piezoelectric element abut against the inner wall are provided, and the metal case hits the lower end of the laminated piezoelectric element. The tubular body includes a contacted substrate and a tubular body joined to the upper surface of the substrate, and the tubular body has a tubular portion extending vertically and a flange portion connected to the lower end of the tubular portion. The substrate has an annular portion, and the substrate and the flange portion are joined at the annular portion, and the region between the laminated piezoelectric element and the tubular body and the annular portion on the upper surface of the substrate. , said the multilayer piezoelectric element Ri erected Bugaa as at intervals surrounding the stacked piezoelectric element,
The erection portion is a piezoelectric actuator characterized in that it is located away from the tubular body . The piezoelectric actuator according to claim 1, wherein the vertical portion is provided closer to the tubular body than the laminated piezoelectric element. The piezoelectric actuator according to claim 1 or 2, wherein the erecting portion continuously surrounds the laminated piezoelectric element. The piezoelectric actuator according to any one of claims 1 to 3, wherein the height of the standing portion is higher than the height corresponding to the thickness of the collar portion. The tubular body has a curved inner surface that gradually expands from the inner surface of the tubular portion to the lower surface of the flange portion, and has a space surrounded by the erecting portion, the substrate, and the tubular body. The piezoelectric actuator according to any one of claims 1 to 4, wherein the piezoelectric actuator is characterized by the above .

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