JP2001244514A - Laminated piezoelectric actuator and injector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated piezoelectric actuator and an injector with high reliability that can sufficiently ensure connection between an internal electrode and an external electrode even in the case of a high-speed continuous operation over an extended period in a highly applied electric field. SOLUTION: There are provided: an actuator body 1 in which piezoelectric bodies 2 and internal electrodes 3a and 3b are stacked alternately, and a pair of external electrodes 6a and 6b which are disposed on different sides of the actuator body 1 and electrically connect the first internal electrodes 3a and the second internal electrodes 3b, respectively. Concave grooves 7, on which the ends of a plurality of internal electrodes 3a and 3b are exposed, are formed on the sides of the actuator body 1 having the external electrodes 6a and 6b formed thereon, respectively. Conductors 9 and insulators 11 are alternately fill the concave grooves 7. Further, an end of a connecting conductive member 15, which has the other end embedded into the conductor 9, is connected to the external electrode 6a or 6b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric actuator and an injection device using the same, and is used, for example, as a fuel injection valve for automobiles, a precision positioning device such as an optical device, and a driving element for preventing vibration. And a jetting device.

[0002]

2. Description of the Related Art Hitherto, in order to obtain a large displacement using an electrostriction effect, a laminated piezoelectric actuator in which piezoelectric bodies and internal electrodes are alternately laminated has been proposed. Multi-layer piezoelectric actuators are classified into two types: co-firing type and single-plate laminating type in which piezoelectric ceramics and internal electrode plates are alternately stacked. The advantage of the multilayer piezoelectric actuator of the type is that it is advantageous for thinning, and is showing its superiority.

As a co-fired type laminated piezoelectric actuator, for example, as described in Japanese Patent Publication No. 6-66484, an insulating layer made of glass is provided at every other end of an internal electrode exposed on the side surface of the actuator body. A laminated piezoelectric actuator in which the outer electrode is covered with a conductive glass film, and the outer electrode is electrically connected to the end of the inner electrode where the insulating layer is not formed between the insulating layers. It has been disclosed.

However, in the laminated piezoelectric actuator disclosed in Japanese Patent Publication No. 6-66484, an insulating layer made of glass is coated on every other end of the internal electrode exposed on the side surface of the actuator body. And the piezoelectric body on both sides are firmly joined, and the insulation between the external electrode and the internal electrode is secured.However, if the piezoelectric element is continuously driven for a long period of time, a crack occurs in the conductive glass film. Separation occurs between the internal electrode and the external electrode through the intermediary, and there is a problem that a voltage is not supplied to some of the piezoelectric bodies and the displacement characteristics change during driving.

Further, in such an actuator, since the lead wire is formed on the external electrode by soldering, the conductive glass film used for the external electrode is eroded by solder, and the reliability of conduction is remarkably improved. There was a problem of lowering.

To solve such a problem, Japanese Patent Application Laid-Open No. 63-15 / 1988
According to Japanese Patent No. 3870, in order to prevent the separation of the external electrode and the internal electrode and to improve the reliability of conduction between the lead wire, the external electrode, and the internal electrode, the end of the internal electrode exposed on the side surface of the actuator body is provided. Every other layer is covered with an insulating layer made of glass, and the external electrodes have the same pitch as the insulating layer.
A concave portion slightly larger than the cross section of the insulating layer is formed, and the insulating layer is accommodated in the concave portion, and the end of the internal electrode on which the insulating layer is not formed is connected to the convex portion between the concave portions by conducting. A laminated piezoelectric actuator bonded with a conductive adhesive is disclosed.

In Japanese Patent Application Laid-Open No. Hei 10-229227, a side surface of a laminated piezoelectric body is coated with a basic metal film,
A three-dimensionally structured conductive electrode is coupled via the base metal coating and the partial contact point, and the three-dimensionally structured conductive electrode is formed to be extensible at the contact point. A stacked piezoelectric actuator is disclosed.

[0008]

In recent years, in order to secure a large amount of displacement under a large pressure with a small piezoelectric actuator, a higher electric field is applied to drive the piezoelectric actuator continuously for a long time. In the case of continuous driving for a long period of time under a high electric field and a high pressure, Japanese Patent Application Laid-Open No. 63-153
In the multilayer piezoelectric actuator disclosed in Japanese Patent Publication No. 870, separation occurs between an internal electrode formed between piezoelectric bodies and external electrodes for the positive electrode and the negative electrode, and voltage is not supplied to some of the piezoelectric bodies. However, there is a problem that the displacement characteristics change during driving.

Further, even in the actuator disclosed in Japanese Patent Application Laid-Open No. 10-229227, separation occurs at the interface between the base metal coating and the piezoelectric body, and the separation proceeds, so that the internal electrode and the external electrode are separated. And the voltage is not supplied to some of the piezoelectric bodies, and the displacement characteristics change during driving.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable laminated piezoelectric actuator and a jetting device which can sufficiently secure connection between an internal electrode and an external electrode even when the device is continuously operated at a high applied electric field at a high speed for a long period of time. And

[0011]

The laminated piezoelectric actuator of the present invention comprises a plurality of piezoelectric bodies and a plurality of internal electrodes alternately laminated, and the internal electrodes are alternately arranged on the first internal electrode or the second internal electrode. A laminated piezoelectric actuator comprising: an actuator main body serving as an electrode; and a pair of external electrodes provided on different side surfaces of the actuator main body and electrically connecting the first internal electrodes and the second internal electrodes, respectively. And forming, on the side surface of the actuator body on which the external electrodes are formed, concave grooves from which the ends of the plurality of internal electrodes are respectively exposed, and alternately filling the concave grooves with a conductor or an insulator. Further, one end of the connection conductive member is provided so as to be embedded in the conductor, and the other end is joined to the external electrode.

According to the present invention, the connection conductive member having one end buried in the conductor in the concave groove formed on the side surface of the actuator body and the external electrode are firmly joined by welding, brazing, or the like. Poor connection between the internal electrode end and the external electrode can be prevented. This makes it possible to provide a highly reliable laminated piezoelectric actuator having high durability without exfoliation or disconnection of the external electrode and the internal electrode even when the external electrode and the internal electrode are driven continuously for a long time at a high applied electric field at a high speed.

Further, since the conductor in the concave groove formed on the side surface of the actuator body is buried at one end of the connection conductive member, peeling of the external electrode can be prevented by the anchor effect of the connection conductive member.

In the present invention, the connecting conductive member and the external electrode are preferably made of an alloy containing Ni and Fe. Thereby, even when a stress acts on the external electrode due to expansion and contraction of the actuator, in order to maintain sufficient strength against the generated stress, for example, the external electrode made of a thin metal plate and the connection conductive member are suppressed from being broken, and high durability is achieved. It is possible to provide a laminated piezoelectric actuator having a property.

Preferably, the external electrode comprises a metal mesh or a metal thin plate and a conductive adhesive covering the metal mesh or the metal thin plate, and the connecting conductive member is joined to the metal mesh or the metal thin plate. In such a configuration, even when stress acts on the external electrode due to expansion and contraction of the piezoelectric actuator, the generated stress can be reduced by deformation of the metal mesh or, for example, a corrugated metal thin plate, thereby suppressing the rupture of the external electrode. Thus, a laminated piezoelectric actuator having high durability can be provided.

Further, the injection device of the present invention provides a storage container having an injection hole, the laminated piezoelectric actuator accommodated in the storage container, and ejects a liquid from the injection hole by driving the laminated piezoelectric actuator. And a valve for causing the pressure to flow. In such an injection device, the durability can be improved based on the high durability of the multilayer piezoelectric actuator.

[0017]

FIG. 1 is a sectional view of a laminated piezoelectric actuator according to the present invention, and FIG. 2 is an enlarged sectional view showing a part of FIG. 1 and FIG.
Shows an actuator body in the form of a quadrangular prism formed by alternately laminating a plurality of piezoelectric bodies 2 and a plurality of internal electrodes 3a, 3b. A first external electrode 6a electrically connected to 3a and a second external electrode 6b electrically connected to the second internal electrode 3b are formed.

The piezoelectric body 2 is made of, for example, lead zirconate titanate Pb (Zr, Ti) O ₃ (hereinafter abbreviated as PZT) or a piezoelectric ceramic material mainly containing barium titanate BaTiO _3. However, the present invention is not limited to these, and any ceramic having piezoelectricity may be used. As the piezoelectric material, as the piezoelectric strain constant d ₃₃ it is high is preferable. Also, the thickness t of the piezoelectric body 2,
That is, the distance between the internal electrode 3a and the internal electrode 3b is set to 0.05 to 0.
Desirably, it is 2 mm.

The internal electrodes 3a and 3b have ends exposed on all four side surfaces of the actuator main body 1. On the side of the actuator main body 1 where the first external electrode 6a is formed, all the internal electrodes 3a and 3b are formed. A plurality of concave grooves 7 each having an exposed end portion of the first internal electrode 3a are formed, and a conductor 9 is provided in the concave groove 7 where the end portion of the first internal electrode 3a is exposed. The groove 7 is filled with an insulator 11.

On the side of the actuator body 1 where the second external electrode 6b is formed, all the internal electrodes 3a, 3b
b, a plurality of concave grooves 7 each exposing an end portion,
The insulator 1 is provided in the groove 7 where the end of the first internal electrode 3a is exposed.
1, the conductor 9 is filled in the concave groove 7 where the end of the second internal electrode 3b is exposed.

The height h of the concave groove 7 in the laminating direction is set to be about １ ／ to ３ of the thickness t of the piezoelectric body 2. This is the groove 7
When the height h in the stacking direction is larger than 1/3 of the thickness t of the piezoelectric body 2, the height h of the concave groove 7 is not satisfied as a groove when the height h of the piezoelectric body 2 is 1/2 of the thickness t. Further, even if the thickness is not more than 1/2, the thickness of the remaining piezoelectric body 2 from which the concave groove 7 is removed becomes thin, the strength cannot be maintained, and there is a risk of being damaged in handling during processing. Also, the groove 7
Is smaller than １ ／ of the thickness t of the piezoelectric body 2, the height h of the concave groove 7 becomes extremely small, making the processing difficult, and the conductor 9 and the insulator 11 This is because defective filling is likely to occur. The cross section of the concave groove 7 is square, but the cross section may be circular.

The conductor 9 is made of a conductive metal material such as an alloy mainly composed of Ag or an alloy mainly composed of Cu.
After the formation of the concave groove 7, it is obtained by filling the concave groove 7 by screen printing, dipping or the like, and firing at about 600 ° C to 900 ° C.

The insulator 11 is made of, for example, glass, epoxy resin, polyimide resin, polyamide-imide resin,
It is made of an insulating material such as silicone rubber, and is obtained by filling the insulating material in the concave groove 7 and curing. still,
The insulator 11 is preferably made of a material having a low Young's modulus, such as silicone rubber. This is because, when filled with a material having a high Young's modulus, exfoliation occurs at the interface between the insulator 11 and the piezoelectric body 2 due to elongation when driven as a piezoelectric actuator, resulting in loss of insulation or destruction, or This is because there is a risk that a crack will be generated in 2 and it will lead to destruction.

Here, the order of forming the conductor 9 and the insulator 11 to be filled in the groove 7 is as follows. The groove 7 is formed in the actuator body 1 obtained by integrally firing. It is preferable to fill the conductors 9 every other one and sinter them, and then fill the remaining grooves 7 with the insulators 11.

The conductor 9 can also be formed using, for example, a polyimide resin. In this case, it is not necessary to particularly consider the order of forming the conductor 9 and the insulator 11. The polyimide resin used as the conductor 9 is a hardly soluble resin that does not dissolve except for concentrated sulfuric acid. Therefore, polyamic acid, a precursor of polyimide, is converted into a suitable solvent, for example,
It is dissolved in N-methyl-2-pyrrolidone (NMP) or tetrahydrofuran (THF) to form a varnish, and the varnish is mixed and kneaded with a conductive material at a desired volume fraction.
Paste. This paste is filled into the groove 7,
The conductor 9 is formed by curing at room temperature to 400 ° C.

It is desirable to use a kneader such as a three-roller mill for kneading. In addition, as the conductive material in the polyimide resin, it is desirable to use metal powder such as nickel, silver, platinum, and gold having a relatively low volume resistivity of Group 6 to 9 of the periodic table.

In the present invention, one end of the connection conductive member 15 is embedded in the conductor 9 and the connection conductive member 1
The other end of 5 is joined to external electrodes 6a and 6b. The connection conductive member 15 is fixed in the conductor 9 by filling the groove with a conductive material by screen printing or dipping after forming the groove, and connecting the conductive material 1 to the conductive material in the groove.
For example, the conductor 9 and the connection conductive member 15 can be electrically and mechanically connected by inserting the conductor 5 and curing the conductor material at room temperature to 400 ° C., for example.

The external electrodes 6a and 6b are composed of a thin metal plate 16 and a conductive adhesive 17,
Are embedded in the conductive adhesive 17 and are
6 is fixed by brazing or welding in a state of being in contact with the connection conductive member 15, whereby the external electrodes 6 a and 6 b are joined to the actuator body 1. The external electrodes 6a and 6b are also joined to the actuator body 1 by a conductive adhesive 17.

The thin metal plate 16 and the connecting conductive member 15 are
Any metal may be used as long as it has conductivity and can be processed, but preferably has a high Young's modulus such as stainless steel (an alloy containing Ni and Fe), a Ni-Fe alloy, and a Ni-Fe-Co alloy. It is desirable to be formed of metal. This is because, by using an alloy mainly composed of Ni and Fe and having a high Young's modulus, even when a stress acts on the external electrodes 6a and 6b due to expansion and contraction of the piezoelectric actuator, sufficient strength is maintained against the generated stress. For this reason, it is possible to suppress the tearing of the metal thin plate 16 and the connection conductive member.

As the conductive adhesive 17 constituting the external electrodes 6a and 6b, a polyimide containing a conductive material having a relatively small volume resistivity, such as nickel, silver, platinum, or gold, belonging to Groups 6 to 9 of the periodic table. Examples include, but are not limited to, resins and conductive silicone rubbers.

The actuator body 1 is mechanically held on both end surfaces of the actuator body 1 in the stacking direction.
Inactive portions 19 for transmitting the generated power to the outside are laminated and joined. Further, although not shown, the entire side surface of the actuator main body 1 including the outer sides of the external electrodes 6a and 6b is covered with an insulating coating material such as silicone rubber, thereby preventing entry of moisture from the outside. In addition, the occurrence of electromigration between the internal electrode and the external electrode can be suppressed, and the reliability of electrode connection can be ensured.

The multilayer piezoelectric actuator configured as described above is manufactured, for example, by the following process. First, lead zirconate titanate Pb (Zr, Ti) O
A slurry is prepared by mixing a calcined powder of a piezoelectric ceramic such as ₃ with a binder made of an organic polymer, and a plasticizer, and a slurry having a thickness of 100 is prepared by a slip casting method.
A ceramic green sheet of ~ 200 µm is prepared.

On one side of this green sheet, an internal electrode 3
A conductive paste mainly composed of silver-palladium to be a and 3b is printed to a thickness of 1 to 10 μm by a screen printing method. After drying the conductive paste, a predetermined number of green sheets to which the conductive paste is applied are laminated by a predetermined number, and green sheets to which the conductive paste is not applied are provided at both ends of the laminate in the laminating direction. Are laminated.

Next, the laminate is pressed while being heated at 50 to 200 ° C. to integrate the laminate. After the integrated laminate is cut to a predetermined size,
The binder is removed for 5 to 40 hours at 900 to 120 hours.
By firing at 0 ° C. for 2 to 5 hours, an actuator body 1 having inactive portions 19 on both end surfaces is obtained. The ends of the internal electrodes 3a and 3b are exposed on the side surfaces of the actuator body 1.

Thereafter, the actuator body 1 is set on a fixing jig, and the side surface of the actuator body 1 is processed using a surface grinder or the like until a predetermined shape is obtained.

Thereafter, on the two opposing side surfaces of the actuator body 1, the portions where the ends of the internal electrodes 3a and 3b are exposed have a depth of 100 to 500 μm and a height h in the stacking direction.
Forms a concave groove 7 of 20 to 50 μm, and after alternately filling the concave groove 7 with a conductive adhesive such as Ag or Ni polyimide, one end of the connection conductive member 15 is inserted thereinto,
The conductive adhesive is heated and cured at room temperature to 400 ° C., and the electrical and mechanical connection between the conductor 9 and the connection conductive member 15 is performed.

Then, the concave groove 7 is filled with an insulator 11 such as silicone rubber. At this time, it is necessary to prevent the conductor 9 and the connection conductive member 15 from being covered with the insulator 11. Thereafter, the other end of the connection conductive member 15 and the external electrode 6
The metal sheets 16a and 6b are joined and fixed by a welding technique such as spot welding, ultrasonic welding, or a technique such as brazing.

Thereafter, the conductive adhesive 17 is applied to the external electrodes 6.
a and 6b are applied between and around the actuator body 1 and the thin metal plate 16 so as to form a
The external electrodes 6a and 6b can be formed on the side surface of the actuator body 1 by evaporating the solvent and causing a curing reaction in the air or nitrogen atmosphere at 0 ° C.

Thereafter, although not shown, an external electrode for the positive electrode,
A lead wire is connected to the negative electrode external electrode, and a coating material such as silicone rubber is coated around the actuator by dipping or the like. In addition, about 1-3k for the positive and negative electrodes
A polarization electric field of V / mm is applied to polarize the piezoelectric body 2 to obtain a multilayer piezoelectric actuator of the present invention.

The laminated piezoelectric actuator of the present invention may have any column shape such as a quadrangular column, a hexagonal column, a circular column, etc., but a quadrangular column shape is desirable from the viewpoint of easy cutting.

In the above example, the external electrodes 6a, 6a
Although the example in which b was formed from the conductive adhesive 17 and the metal sheet 16 has been described, the present invention
A metal mesh may be used. In this case, the stress can be effectively absorbed.

FIG. 3 shows an injection device of the present invention.
In the figure, reference numeral 51 indicates a storage container. An injection hole 53 is provided at one end of the storage container 51, and a needle valve 55 that can open and close the injection hole 53 is stored in the storage container 51.

A fuel passage 57 is provided in the injection hole 53 so as to be communicable. The fuel passage 57 is connected to an external fuel supply source, and the fuel is constantly supplied to the fuel passage 57 at a constant high pressure. Therefore, when the needle valve 55 opens the injection hole 53, the fuel supplied to the fuel passage 57 is injected at a constant high pressure into a fuel chamber (not shown) of the internal combustion engine.

The upper end of the needle valve 55 has a large diameter and serves as a piston 61 slidable with a cylinder 59 formed in the storage container 51. The above-mentioned piezoelectric actuator 63 is stored in the storage container 51.

In such an injection device, when the piezoelectric actuator 63 expands by applying a voltage, the piston 61
Is pressed, the needle valve 55 closes the injection hole 53, and the supply of fuel is stopped. When the application of the voltage is stopped, the piezoelectric actuator 63 contracts, and the disc spring 65
Pushes back the piston 61, and the injection hole 53
And the fuel is injected.

[0046]

EXAMPLE A 200 μm thick green sheet mainly composed of PZT was formed by printing a 5 μm thick internal electrode paste mainly composed of Ag / Pd. 300 green sheets to which the internal electrode paste was applied were laminated, and thereafter, green sheets to which the internal electrode paste was not applied were laminated on both surfaces, and were joined by heating and integrated.

This laminate is cut into a length of 10 mm and a width of 10 mm, and a maximum temperature of 700 to 800 ° C.
Debinding was performed at 0 hours. After that, the maximum temperature 900
Calcination at 3 ° C. to 1100 ° C. for 3 to 5 hours.
Was obtained.

Next, the obtained actuator main body 1 was set on a fixing jig, and the side surface of the actuator main body 1 was ground. Thereafter, the portions (piezoelectric plates and internal electrodes) of the shape shown in FIG. 2 where the internal electrodes 3a and 3b are exposed on the side surface of the actuator body 1 are cut off by a cut saw, and 500 μm in the depth direction and the stacking direction Height h is 50
A μm concave groove 7 was formed.

Thereafter, a silver polyimide conductive adhesive is injected into the concave groove 7 of the actuator body 1 by using a dispenser, and filling is performed, and the inside thereof is 30 μm thick and 1 m wide.
m, insert a Kovar foil or a silver foil of 2 mm in length, 12
After preliminary drying at 0 ° C. for 10 minutes, curing was performed at 220 ° C. for 1 hour, and one end of the connection conductive member 15 was embedded and fixed in the conductor.

Next, the groove 7 not filled with the conductor 9
Inside, silicone rubber was applied at room temperature and filled by vacuum degassing. Thereafter, a metal thin plate 16 made of Kovar foil or silver was arranged on the side surface of the actuator body 1, and the other end of the connecting conductive member 15 and the metal thin plate 16 were joined by ultrasonic welding.

Thereafter, a conductive adhesive made of silver polyimide was applied between and around the actuator body 1 and the thin metal plate 16, and was cured and bonded in a drying oven at 220 ° C. Thereafter, the lead wires are soldered to a thin metal plate, and externally covered with silicon rubber, and the positive electrode and the negative electrode are covered with 2.
Polarization was performed by applying a DC electric field of 5 kV / mm for 30 minutes to obtain a laminated piezoelectric actuator.

Then, stress 2 is applied to the laminated piezoelectric actuator.
When 0 MPa was applied and the displacement was confirmed at a drive voltage of 200 V, a displacement of 40 μm was obtained for each sample. Next, a stress of 20 MPa was applied, a pulse alternating electric field of 0 to 200 V was applied at a frequency of 60 Hz, a continuous driving test was performed, and peeling and disconnection of the external and internal electrodes were confirmed. Table 1 shows the results.

As a comparison, only the insulator is filled in the concave groove to insulate it from one internal electrode, and the other end of the internal electrode is exposed to the actuator body. A laminated piezoelectric actuator was prepared in which the coated external electrodes were connected (the ends of the internal electrodes were adhered with a conductive adhesive), a stress of 20 MPa was applied thereto, and the displacement was confirmed at a driving voltage of 200 V.
In the initial evaluation, a displacement amount of 40 μm was shown similarly to the above-mentioned sample. In addition, a continuous driving test was performed in the same manner, and the results are also shown in Table 1.

[0054]

[Table 1]

[0055] From Table 1, the laminated piezoelectric actuator of the present invention obtained by bonding the connection conductive member and the metal sheet, the following driving cycle ¹⁰⁷ cycles, peeling or disconnection of the external electrodes and the internal electrodes did not occur. Then, by the material of the connection conductive member and the metal sheet to high Young's modulus Kovar, in the driving cycle ¹⁰⁹ cycles, breakage of the release and the external electrodes of the external electrode and the internal electrodes did not occur.

Further, in the conventional comparative example in which the grooves were formed alternately and only the insulator was filled in the grooves, the external electrode and the internal electrode peeled off in a driving cycle of 5х10 ⁵ cycles.

[0057]

According to the laminated piezoelectric actuator of the present invention, a connection conductive member having one end embedded in a conductor in a concave groove formed on the side surface of the actuator body and an external electrode are welded, brazed, or the like. By firmly joining, the end of the internal electrode and the external electrode can be reliably connected. This provides a highly reliable laminated piezoelectric actuator with high durability without exfoliation of the external electrode and the internal electrode or disconnection of the external electrode even when driven for a long period of time at a high applied electric field at a high speed. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a laminated piezoelectric actuator of the present invention.

FIG. 2 is an enlarged sectional view showing a part of the multilayer piezoelectric actuator of FIG. 1;

FIG. 3 is an explanatory view showing an injection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Actuator main body 2 ... Piezoelectric body 3a, 3b ... Internal electrode 6a, 6b ... External electrode 7 ... Concave groove 9 ... Conductor 11 ... Insulator 15 ... Connection conductive member 16 Metal thin plate 17 Conductive adhesive 51 Storage container 53 Injection hole 55 Valve 63 Piezoelectric actuator

Claims (4)

[Claims] An actuator body in which a plurality of piezoelectric bodies and a plurality of internal electrodes are alternately laminated, wherein the internal electrodes are alternately provided as first internal electrodes or second internal electrodes; A laminated piezoelectric actuator comprising: a pair of external electrodes provided on a side surface and electrically connecting the first internal electrodes to each other and the second internal electrodes to each other, wherein the actuator body on which the external electrodes are formed On the side surface of each of the plurality of internal electrodes, a concave groove from which ends of the plurality of internal electrodes are respectively exposed is formed, and a conductor or an insulator is alternately filled in the concave groove. Wherein the other end is joined to the external electrode. 2. The connection conductive member and the external electrode are made of an alloy containing Ni and Fe.
13. The laminated piezoelectric actuator according to claim 1. 3. An external electrode comprising a metal thin plate or a metal mesh and a conductive adhesive covering the metal thin plate or the metal mesh, and a connecting conductive member is joined to the metal thin plate or the metal mesh. The multilayer piezoelectric actuator according to claim 1. 4. A storage container having an injection hole, the multilayer piezoelectric actuator according to any one of claims 1 to 3 stored in the storage container, and the injection hole driven by driving the multilayer piezoelectric actuator. And a valve for ejecting a liquid from the device.