JP6927848B2 - Piezoelectric actuator - Google Patents

Description

The present disclosure relates to piezoelectric actuators, for example, piezoelectric actuators used in mass flow controllers, precision positioning devices for XY tables, and the like.

As a piezoelectric actuator, a square columnar 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 the inner wall are known. Here, when the laminated piezoelectric element is sealed in the metal case, the entire end surface of the laminated piezoelectric element is adhered to the metal case with a bonding material (see, for example, Patent Document 1).

Patent No. 3039771

When the entire end face of the laminated piezoelectric element and the metal case are firmly bonded with a bonding material, stress is concentrated on the part farthest from the center of gravity of the figure at the lower end of the laminated piezoelectric element, and the bonding is performed at this part. Cracks may occur from the material to the laminated piezoelectric element, and the function of the piezoelectric actuator may deteriorate.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a piezoelectric actuator in which cracks are suppressed from occurring.

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 . The laminate includes a laminate in which a piezoelectric layer and an internal electrode layer are laminated, the laminate is a polygonal columnar having a plurality of side surfaces, and the lower end of the laminated piezoelectric element is bonded to the metal case with a bonding material. The bonding material is not provided at least at the lower end of the laminated piezoelectric element at the position farthest from the center of gravity of the figure when viewed from the stacking direction, and protrudes outward from the lower end of the laminated body when viewed from the stacking direction. It is characterized by having a protruding portion.

According to the piezoelectric actuator of the present disclosure, stress concentration at the lower end of the laminated piezoelectric element at the portion farthest from the center of gravity of the figure is eliminated, so that it is possible to suppress the occurrence of cracks at this portion.

It is the schematic perspective view which shows the example of the piezoelectric actuator. It is a schematic vertical sectional view of the piezoelectric actuator shown in FIG. 1 cut along the line II-II. It is a schematic perspective view which shows the laminated type piezoelectric element shown in FIG. It is the schematic of the area A shown in FIG. It is an enlarged sectional view of the main part of another example of a piezoelectric actuator. It is a partial transmission bottom view of another example of a piezoelectric actuator. It is a partial transmission bottom view of another example of a piezoelectric actuator. It is a partial transmission bottom view of another example of a piezoelectric actuator. It is an enlarged sectional view of the main part of another example of a piezoelectric actuator. It is an enlarged sectional view of the main part of another example of a piezoelectric actuator.

An embodiment of the piezoelectric actuator will be described with reference to the drawings.

The piezoelectric actuator 10 shown in FIGS. 1 and 2 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.

As shown in FIG. 3, the laminated piezoelectric element 1 is, for example, a piezoelectric element including a laminated body 13 in which a plurality of piezoelectric layer 11s and internal electrode layers 12 are alternately laminated.

The laminated body 13 has, for example, a rectangular parallelepiped shape having a length of 0.5 mm to 10 mm, a width of 0.5 mm to 10 mm, and a height of 1 mm to 100 mm. The shape of the laminated body 13 may be a hexagonal column shape, an octagonal column shape, a columnar shape, or the like.

The piezoelectric layer 11 is made of ceramics having piezoelectric characteristics. As such ceramics, for example, lead zirconate titanate (PbZrO _3- PbTIO ₃ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ) and the like can be used. The thickness of the piezoelectric layer 11 is, for example, 3 μm to 250 μm.

The internal electrode layer 12 is formed by simultaneous firing with the piezoelectric layer 11. The internal electrode layer 12 includes a first internal electrode layer 121 and a second internal electrode layer 122. For example, a driving voltage can be applied to the piezoelectric layer 11 sandwiched between the first internal electrode layer 121 as a positive electrode and the second internal electrode layer 122 as a negative electrode or a ground electrode. Here, the first internal electrode layer 121 is drawn out on one side surface of the laminated body 13, and the second internal electrode layer 122 is drawn out on the other side surface. As such a material, for example, a conductor containing silver, silver-palladium, silver-platinum, copper or the like as a main component can be used. The thickness of the first internal electrode layer 121 and the second internal electrode layer 122 is, for example, 0.1 μm to 5 μm.

Further, the laminated body 13 may include a planned break layer 14. Here, the planned break layer 14 is a layer for relaxing the stress generated by driving the laminated piezoelectric element 1. Examples of the planned breaking layer 14 include a porous metal layer that does not function as the internal electrode layer 12, a metal layer that has been cracked in advance, and the like.

Further, an external electrode 15 is provided on each of the pair of side surfaces from which one of the end faces of the first internal electrode layer 121 and the second internal electrode layer 122 is drawn out, and the drawn out first internal electrode layer is provided. It is electrically connected to 121 or a second internal electrode layer 122.

The external electrode 15 can be produced by baking a conductive paste containing a metal such as Ag or Cu and glass. Here, when the external electrode 15 is viewed in a cross section perpendicular to the side surface of the laminated body 13, the thickness of the external electrode 15 is, for example, 5 μm to 70 μm. For example, a lead member is joined to the end of the external electrode 15, and an electrical connection with an external circuit is made via the lead member.

On the other hand, the end faces of both the first internal electrode layer 121 and the second internal electrode layer 122 reach, for example, the other pair of side surfaces of the laminated body 13 facing each other, and if necessary, from resin, insulating ceramics, or the like. A coating layer may be provided.

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 metal bodies such as SUS304 and SUS316L, for example.

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 mm 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 out. 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 collar 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 portion of the substrate 21 and the flange portion 222 of the tubular body 22 are welded, for example, in a state where a compressive load is applied to the laminated piezoelectric element 1. The substrate 21 is formed with two through holes through which the lead pins 43 can be inserted, and the lead pins 43 are inserted through the through holes. Then, for example, soft glass 44 is filled in the gap between the through holes, and the lead pin 43 is fixed. A lead wire 41 is connected to the tip of the lead pin 43, and the lead wire 41 is attached to the external electrode 15 with solder 42, and a drive voltage is applied to the laminated piezoelectric element 1 via the lead pin 43 and the lead wire 41. Is to be applied.

The outer diameter of the lid 23 is about the same as the inner diameter of the opening on one end side of the cylinder 22. The lid 23 is fitted from the one end side opening of the tubular body 22, and its side surface is welded, for example, to the inner wall in the vicinity of the one end side opening of the tubular body 22 (near the upper end). At this time, the flange portion 222 of the tubular body 22 and the base 21 are welded to each other with a compressive load applied to the laminated piezoelectric element 1.

Then, as shown in FIGS. 2 and 4, the lower end of the laminated piezoelectric element 1 is bonded to the metal case 2 with the bonding material 3, and the bonding material 3 is at least the laminated piezoelectric element 1 when viewed from the stacking direction. It is not provided at the part farthest from the center of gravity of the figure at the lower end.

The bonding material 3 for joining the lower end of the laminated piezoelectric element 1 to the metal case 2 is, for example, an epoxy resin, a polyimide resin, a urethane resin, or the like. The thickness of the bonding material 3 between the lower end of the laminated piezoelectric element 1 and the upper surface of the substrate 21 is, for example, 0.01 mm to 0.30 mm.

The laminated piezoelectric element 1 expands and contracts in the laminating direction, and at the same time expands and contracts in the direction perpendicular to the laminating direction. At this time, since the portion of the lower end surface of the laminated piezoelectric element 1 joined to the metal case 2 that is farthest from the center of gravity of the figure moves the largest, stress is concentrated on this portion and cracks are likely to occur. Specifically, cracks occur from the portion of the lower end surface of the laminated piezoelectric element 1 farthest from the center of gravity of the figure and the vicinity of the joint between the joining material 3 and toward the inside of the laminated piezoelectric element 1 after long-term use. Cracks may develop.

On the other hand, since the bonding material 3 is not provided at least at the lower end of the laminated piezoelectric element 1 at the lower end of the laminated piezoelectric element 1 at the portion farthest from the center of gravity of the figure when viewed from the laminating direction of the laminated piezoelectric element 1, stress on this portion is applied. It is possible to prevent the concentration from being lost and cracks from occurring at this site. Therefore, the durability of the piezoelectric actuator 10 is improved.

Here, at least the lower end of the laminated piezoelectric element 1 is not provided at the portion farthest from the center of gravity of the figure. If the laminated piezoelectric element 1 has a quadrangular columnar shape and the lower end surface is quadrangular, it is provided at four corners. It means that it has not been done. Further, when the laminated piezoelectric element 1 has a columnar shape (when there is no distance and the total distance is the same), it means that the laminated piezoelectric element 1 does not reach the outer peripheral portion.

When the upper end of the laminated piezoelectric element 1 is bonded to the metal case 2, the bonding material between the upper end of the laminated piezoelectric element 1 and the metal case 2 may have the same shape.

Further, the laminated piezoelectric element 1 is provided on the side surface of the laminated body 13 in which the piezoelectric layer 11, the first internal electrode layer 121, and the second internal electrode layer 122 are laminated, and the first. The internal electrode layer 121 or the second internal electrode layer 122 of the above is provided with an external electrode 15 electrically connected to the internal electrode layer 121. In this case, as shown in FIG. 5, the bonding material 3 is located inside the outer edge of the active region 130 where the first internal electrode layer 121 and the second internal electrode layer 122 overlap when viewed from the stacking direction. It may be provided so as to do so.

Specifically, the first internal electrode layer 121 and the second internal electrode layer 122 have, for example, a rectangular shape. Then, in the first internal electrode layer 121 and the second internal electrode layer 122, the end portion on the side electrically connected to the external electrode 15 reaches the side surface of the laminated body 13, but the external electrode 15 and electricity The end portion on the side opposite to the side to which the laminate is connected is located, for example, 0.1 mm to 1.5 mm inside the side surface of the laminated body 13 in order to prevent a short circuit. The other pair of ends of the first internal electrode layer 121 and the second internal electrode layer 122 may reach a side surface where the external electrode 15 is not provided, and from this side surface, for example, 0.1 mm to It may be located 1.5 mm inside.

Here, the active region 131 in which the first internal electrode layer 121 and the second internal electrode layer 122 overlap when viewed from the stacking direction expands and contracts, but when viewed from the stacking direction, the first internal electrode layer 121 Since the inert region 132 in which the second internal electrode layer 122 and the second internal electrode layer 122 do not overlap with each other is difficult to expand and contract, stress is applied to the boundary between them. Therefore, by arranging the bonding material 3 so as not to cover the boundary between the active region 131 and the inactive region 132, it is possible to suppress the occurrence of cracks in the bonding material 3 and the laminated piezoelectric element 1 at this portion. Durability is improved.

Further, as shown in FIG. 6, the joining material 3 may have a protruding portion 31 protruding outward from the lower end of the laminated body 13 when viewed from the laminating direction. When the laminated piezoelectric element 1 is driven to expand and contract, the stress is also transmitted to the protruding portion 31 of the bonding material 3, so that the stress is dispersed and between the lower end of the laminated piezoelectric element 1 and the base 21 of the metal case 2. The resulting stress is relieved. Further, since the protruding portion 31 of the bonding material 3 is not easily affected by the pulling or pressing due to the expansion and contraction of the laminated piezoelectric element 1, the bonding material 3 is less likely to be peeled off when the laminated piezoelectric element 1 is driven, and the durability is further improved. ..

Note that FIG. 6 shows the lower surface of the laminated piezoelectric element 1 and the bonding material 3 that have passed through the metal case 2, and even if there is a protruding portion 31 of the bonding material 3, the bonding material 3 is It is not provided at the four corners of the lower surface of the laminated piezoelectric element 1. When the length of one side of the lower end quadrangle is 0.5 mm to 10 mm when the laminated body 13 is a quadrangular columnar shape, the maximum protrusion distance in the direction perpendicular to the side surface of the laminated body 13 is, for example, within the range of 0.2 mm to 3 mm. Set in.

Further, as shown in FIG. 7, the laminated body 13 is a polygonal columnar having a plurality of side surfaces, and the joining material 3 protrudes outward from the lower end of the laminated body 13 on all of the plurality of side surfaces when viewed from the laminating direction. It may have a part 31. In other words, it is preferable that the protruding portion 31 protrudes from all the lower ends of the plurality of side surfaces of the laminated body 13 when viewed from the stacking direction. As a result, the stress is dispersed in a well-balanced manner, and the durability is further improved. In particular, as shown in FIG. 8, the joining material 3 may be seen through a plane.

When the length of one side of the lower end quadrangle is 0.5 mm to 10 mm when the laminated body 13 is a quadrangular columnar shape, the maximum protrusion distance in the direction perpendicular to the side surface is, for example, 0 on all the side surfaces of the laminated body 13. .Set within the range of 2 mm to 3 mm.

Further, as shown in FIG. 9, the protruding portion 31 is raised higher than the lower end of the laminated piezoelectric element 1 and may be fixed to the side surface of the laminated body 13. As a result, the stress concentration points are dispersed to the side surface of the laminated piezoelectric element 1, and the laminated piezoelectric element 1 and the bonding material 3 are more firmly bonded to each other to improve durability.

The protruding portion 31 is set to be higher than the lower surface of the laminated piezoelectric element 1 by, for example, 0.1 mm to 2.0 mm.

At this time, as shown in FIG. 9, the distance from the side surface of the laminated body 13 to the outermost protruding portion of the protruding portion 31 is the distance from the lower end of the laminated piezoelectric element 1 to the highest raised portion. May be longer than. Here, the distance from the side surface of the laminated body 13 to the portion protruding to the outermost side means the distance in the direction perpendicular to the side surface. As a result, the stress in the horizontal direction (direction perpendicular to the stacking direction), which is larger than the vertical direction (stacking direction) applied when the laminated piezoelectric element 1 is driven, is further relaxed.

Further, as shown in FIG. 10, the ridge portion at the lower end of the laminated piezoelectric element 1 may be a C surface or an R surface. As a result, the stress concentration in the vicinity of the ridge portion is suppressed, and the stress is relaxed by spreading the bonding material 3 in the ridge portion, and the durability is improved.

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 calendar roll method. As the piezoelectric ceramic, any ceramic having piezoelectric characteristics may be used, and for example, lead titanate zirconate (PbZrO _3- PbTIO ₃ ) 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, for example, a conductive paste is prepared by adding and mixing a binder and a plasticizer to powder of a silver-palladium alloy. This conductive paste is printed on the ceramic green sheet in the pattern of the internal electrode layer 12 by a screen printing method. Next, a plurality of ceramic green sheets on which the conductive paste is printed are laminated, and a plurality of ceramic green sheets on which the conductive paste is not printed are laminated on both ends in the stacking direction to obtain a laminated molded product. Here, if necessary, a ceramic green sheet coated with the conductive paste may be arranged in the laminated molded body so as to form a planned breaking layer 14 composed of a porous metal layer.

After the laminated molded body is debindered at a predetermined temperature, it is fired at 900 to 1200 ° C. and ground to a predetermined shape using a surface grinding machine or the like to produce the laminated body 13.

The laminate 13 is not limited to the one produced by the above manufacturing method, and any production can be made as long as the laminate 13 formed by laminating a plurality of the piezoelectric layer 11 and the internal electrode layer 12 can be produced. It may be produced by a method.

Next, the external electrode 15 is formed using a conductive paste containing a metal such as Ag or Cu. Specifically, a binder is added to silver particles and glass powder to prepare a silver glass-containing conductive paste, and a screen printing method or a dispensing method is applied to the pair of opposite side surfaces of the derived laminate 13 of the internal electrode layer 12. After printing and drying, the baking process is performed at a temperature of about 500 to 800 ° C. As a result, the external electrode 15 is formed.

Next, if necessary, a resin such as epoxy, silicone, or nylon as a coating layer is formed on a pair of side surfaces from which both internal electrode layers 12 are derived from the side surfaces of the laminate 13 by printing or a dispense method.

After that, a DC electric field of 0.1 to 3 kV / mm is applied to the external electrode 5 to polarize the piezoelectric layer 11 constituting the laminated body 13, thereby completing the laminated piezoelectric element 1.

Next, the external electrode 15 and the lead wire 41 are soldered.

Further, a substrate 21 is prepared in which an annular portion (not shown) for resistance welding is formed by cutting and a through hole is formed by hole machining. A lead pin 43 is inserted into each of the two through holes formed in the substrate 21, and a soft glass 44 is filled in the gap to fix the lead pin 43. Further, the lower end portion of the laminated piezoelectric element 1 is attached to the upper surface of the substrate 21 with a bonding material 3. Glue. 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.

Here, the bonding material 3 is applied so that it is not provided at least at the lower end of the laminated piezoelectric element 1 at the position farthest from the center of gravity of the figure when viewed from the laminating direction, and an appropriate amount of coating is applied so as to obtain a desired shape. Adjust and apply.

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 portion 221 of the tubular body 22.

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, a DC electric field of 0.1 to 3 kV / mm is applied to the lead pin 43 attached to the substrate 21 to polarize the laminated body 13.

By the above manufacturing method, the piezoelectric actuator 10 of the present embodiment can be obtained.

The piezoelectric actuator 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.

A ceramic green sheet obtained by printing a conductive paste as an internal electrode layer 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. 260 sheets were laminated, and 20 ceramic green sheets without conductive paste were laminated on the upper and lower layers to prepare a laminated molded body.

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, 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 metal body constituting a positioning portion by cutting and an annular portion to be welded were provided, and a substrate having a shape shown in FIG. 2 having through holes formed at two locations was produced. Then, a lead pin was attached to the through hole formed in the substrate with soft glass.

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

Here, as an example (Sample No. 1), the one in the state of the bonding material shown in FIG. 4 was prepared. First, an epoxy resin was used as a bonding material for adhering the laminate and the metal case, and 0.1 to 10 mg was applied to the center of the bottom surface of the laminate by a dispenser to adhere the metal case. At this time, it was visually confirmed that the epoxy resin did not reach the end farthest from the center of gravity. Then, it was produced by heating in an oven at 150 to 200 ° C. to cure the epoxy resin.

On the other hand, as a comparative example (Sample No. 2), the epoxy resin was prepared so as to reach the four corners of the laminate, which is the farthest end from the center of gravity.

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 the lid were welded. Then, this welded material is put on the laminated piezoelectric element adhered to the substrate, the cylinder is pulled with a predetermined load, a load is applied to the laminated piezoelectric element, and then the contact portion between the cylinder and the substrate is resisted. Welded by welding.

Finally, a DC electric field of 3 kV / mm was applied to the two lead pins for 15 minutes to perform polarization treatment, and the piezoelectric actuators of Example (Sample No. 1) and Comparative Example (Sample No. 2) were produced.

Then, these piezoelectric actuators were subjected to a continuous drive test at 150 V and 80 Hz.

As a result, the sample No. which is a comparative example. The piezoelectric actuator of 2 cracks from the bonding interface between the bonding material and the laminated piezoelectric element toward the inside of the laminated piezoelectric element by continuous driving ^{5 × 10 6 times, short-circuits between the internal electrode layers, and sparks.} It stopped driving.

On the other hand, the sample No. which is an example. The piezoelectric actuator of No. 1 was stably driven without change even after ^{1 × 10 8 times of continuous driving.} When the end portion of the laminated piezoelectric element was observed after driving, there was no crack.

From the above results, it was found that the piezoelectric actuator of the present embodiment has excellent long-term durability.

10 ... Piezoelectric actuator 1 ... Piezoelectric element 11 ... Piezoelectric layer 12 ... Internal electrode layer 121 ... First internal electrode layer 122 ... Second internal electrode layer 13 ... Laminated body 14 ... Scheduled breaking layer 15 ... External electrode 2 ... Metal case 21 ... Base 22 ... Cylindrical body 221 ... Cylindrical portion 222 ... Flange portion 23 ...・ Lid body 3 ・ ・ ・ Joint material 31 ・ ・ ・ Overhanging part

Claims (5)

The laminated piezoelectric element 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 the inner wall. The laminated piezoelectric element includes a piezoelectric layer and an internal electrode layer. The laminated body is a polygonal columnar shape having a plurality of side surfaces, and the lower end of the laminated piezoelectric element is bonded to the metal case with a bonding material. It is not provided at least at the lower end of the laminated piezoelectric element at the position farthest from the center of gravity of the figure when viewed from the stacking direction, and has a protruding portion protruding outward from the lower end of the laminated body when viewed from the stacking direction. the piezoelectric actuator, characterized in that there. Before SL bonding material, a piezoelectric actuator according to claim 1, characterized in that it has a protruding portion that protrudes outward in all from the lower end of the laminate when viewed from the laminate direction of said plurality of sides. The piezoelectric actuator according to claim 1 or 2 , wherein the protruding portion is raised higher than the lower end of the laminated piezoelectric element and is fixed to the side surface of the laminated body. The overhanging portion is characterized in that the distance from the side surface of the laminated body to the outermost protruding portion is longer than the distance from the lower end of the laminated piezoelectric element to the highest raised portion. 3. The piezoelectric actuator according to 3. The piezoelectric actuator according to any one of claims 1 to 4 ridge portions of the lower end of the laminated piezoelectric element is characterized that it is C plane or R plane.

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