JP2006013437A - Laminated piezoelectric element, its manufacturing method, and injection device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated piezoelectric element excellent in desired amount of displacement and durability even when it is continuously driven for a long period of time under a high voltage and high pressure, and also, to provide its manufacturing method and an injection device using it. <P>SOLUTION: The laminated piezoelectric element has a laminated body composed by alternately laminating at least one piezoelectric body 1 and a plurality of electrode layers 2 so that the electrode layers 2 sandwich the piezoelectric body 1 in-between and partially face each other. The laminated piezoelectric element is provided with a pair of external electrodes 4 for impressing a voltage between the electrode layers 2 on the side face of the laminated body. A void penetrating the electrode layers 2 in the lamination direction of the laminated body is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminated piezoelectric element and an injection device, for example, a fuel injection device for an automobile engine, a liquid injection device such as an inkjet, a drive element mounted on a precision positioning device such as an optical device, a vibration prevention device, and the like, and a combustion Sensor elements mounted on pressure sensors, knock sensors, acceleration sensors, load sensors, ultrasonic sensors, pressure sensitive sensors, yaw rate sensors, etc., and circuit elements mounted on piezoelectric gyros, piezoelectric switches, piezoelectric transformers, piezoelectric breakers, etc. The present invention relates to a stacked piezoelectric element and a jetting device used.

  2. Description of the Related Art Conventionally, a multilayer piezoelectric actuator in which piezoelectric bodies and electrode layers are alternately stacked is known as one using a multilayer piezoelectric element. Multilayer piezoelectric actuators are classified into two types: simultaneous firing types and stack types in which piezoelectric ceramics and electrode layers are alternately stacked. Considering low voltage and manufacturing cost reduction, Therefore, the simultaneous firing type laminated piezoelectric actuator is showing superiority.

  FIG. 5A shows a conventional laminated piezoelectric element 53, in which piezoelectric bodies 51 and electrode layers 52 are alternately laminated to form a laminated body 53, and inert layers are formed on both end faces in the laminating direction. 55 are stacked. One end portion of the electrode layer 52 is alternately exposed on the side surface of the stacked body 53, and the external electrode 70 is formed on the side surface of the stacked body 53 where the end portion of the electrode layer 52 is exposed. The other end of the electrode layer 52 is covered with an insulator 61 and insulated from the external electrode 70. When used as a multilayer piezoelectric actuator, the lead wire 72 is connected and fixed to the external electrode 70 by soldering.

  As a manufacturing method of such a multilayer piezoelectric element, an electrode paste to be an electrode layer 52 is printed on a ceramic green sheet to be a piezoelectric body 51 in a pattern having a predetermined electrode structure, and this electrode layer paste is applied. A laminated piezoelectric element was produced by producing a laminated molded body obtained by laminating a plurality of green sheets, firing this, and baking a conductive paste serving as the external electrode 70 on the side surface (for example, Patent Document 1).

  In such a laminated piezoelectric element, generally, piezoelectric bodies 51 and electrode layers 52 are alternately laminated to form a laminated body 53, and the electrode layer 52 is formed in the electrode layer as shown in FIG. The structure has no voids. In the field of multilayer ceramic capacitors, as shown in Patent Document 2, the stress generated during firing is relieved, the substrate has excellent reliability such as bend resistance, and has stable electrical characteristics and high quality. In order to provide a multilayer ceramic capacitor, it has been proposed to provide a gap at the end of the electrode layer 52.

As the electrode layer 52, an alloy of silver and palladium is used. Further, in order to simultaneously fire the piezoelectric body 51 and the electrode layer 52, the electrode layer 52 has a metal composition of 70% by mass of silver and 30% by mass of palladium. (See, for example, Patent Document 3).
JP-A-61-133715 JP 2002-231558 A Japanese Utility Model Publication No. 1-130568

  By the way, in recent years, it is required that a large amount of displacement be generated under a large pressure by a small piezoelectric actuator.

  Here, unlike a conventional multilayer electronic component (for example, a multilayer ceramic capacitor), the multilayer piezoelectric element is characterized in that the ceramic of the piezoelectric body 51 is greatly deformed (displaced) when an electric field is applied with energization. Further, the number of times of driving and the number of times of porcelain deformation of the piezoelectric body 51 are the same.

  Thus, in the multilayer piezoelectric element with displacement, the electrode layer has a dense structure for the purpose of maintaining the durability of the electrode layer. However, if the electrode layer has a dense structure, it exerts an action of constraining the displacing piezoelectric body, so that it has been difficult to efficiently obtain a large amount of displacement as required in recent years.

  Therefore, the present inventor has tried to improve the displacement amount of the multilayer piezoelectric element by providing a gap in the electrode layer. As a result, it has been found that the amount of displacement is remarkably improved by providing a gap in the electrode layer. At the same time, it was found that the durability is improved, unlike the conventional way of thinking.

  Accordingly, the present invention has an object to provide a laminated piezoelectric element that is excellent in displacement and durability when a piezoelectric actuator is driven under high voltage and high pressure, a manufacturing method thereof, and an injection device using the same. And

  In view of the above-described problems, the multilayer piezoelectric element of the present invention is configured by alternately laminating at least one piezoelectric body and a plurality of electrode layers so that the electrode layers partially face each other with the piezoelectric body in between. A laminated piezoelectric element having a pair of external electrodes for applying a voltage between the electrode layers on a side surface of the laminated body, and a gap penetrating the electrode layer in the lamination direction of the laminated body. Is provided.

  The multilayer piezoelectric element of the present invention is characterized in that a gap penetrating the electrode layer is provided in all the electrode layers.

  The multilayer piezoelectric element of the present invention has a multilayer body in which at least one piezoelectric body and a plurality of electrode layers are alternately stacked, and the electrode layers are alternately connected to the side surfaces of the multilayer body. In the laminated piezoelectric element having a pair of external electrodes and driven by applying an electric field to the external electrodes, a gap that occupies 5 to 70% of the area of the electrode layer is provided in the electrode layer. Features.

  The multilayer piezoelectric element of the present invention is characterized in that the maximum width of the gap is 1 μm or more.

  The multilayer piezoelectric element of the present invention has a starting point where the interface between the electrode portion and the gap in the electrode layer is in contact with the piezoelectric body, and the angle between the tangent line from the starting point to the electrode portion and the piezoelectric body is 60 degrees or more. It is characterized by being.

  The multilayer piezoelectric element of the present invention is characterized in that the metal composition in the electrode layer contains a group 8-10 metal and / or a group 11 metal as a main component.

  In the multilayer piezoelectric element of the present invention, when the content of the group 8-10 metal in the electrode layer is M1 (mass%) and the content of the group 11 metal is M2 (mass%), 0 <M1 ≦ 15 85 ≦ M2 <100 and M1 + M2 = 100 are satisfied.

  In the multilayer piezoelectric element of the present invention, the group 8-10 metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the group 11 metal is at least of Cu, Ag, and Au. It is one or more types.

  The multilayer piezoelectric element of the present invention is characterized in that the group 8-10 metal is at least one of Pt and Pd, and the group 11 metal is at least one of Ag and Au.

  The laminated piezoelectric element of the present invention is characterized in that the group 8-10 metal is Cu.

  The multilayer piezoelectric element of the present invention is characterized in that the Group 8-10 metal is Ni.

  The multilayer piezoelectric element of the present invention is characterized in that an inorganic composition containing at least one of BN, TiN, and ZrN as a main component is added to the electrode layer.

  The multilayer piezoelectric element of the present invention is characterized in that the piezoelectric body contains a perovskite oxide as a main component.

The multilayer piezoelectric element of the present invention is characterized in that the piezoelectric body contains a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ as a main component.

  In the multilayer piezoelectric element of the present invention, the electrode layer whose end is exposed on the side surface of the multilayer body and the electrode layer whose end is not exposed are alternately configured, and the end is not exposed. A groove is formed in the piezoelectric portion between the electrode layer and the external electrode, and the groove is filled with an insulator having a Young's modulus lower than that of the piezoelectric body.

  The method for manufacturing a laminated piezoelectric element of the present invention has a piezoelectric body formed by alternately laminating at least one piezoelectric body and a plurality of electrode layers, and the electrode layers are alternately arranged on the side surfaces of the laminated body. In the method of manufacturing a laminated piezoelectric element comprising a pair of external electrodes connected to each other and driven by applying an electric field to the external electrodes, the electrode layer is composed of two or more mixed materials, It is characterized in that it includes a step of calcining after calcination at a temperature not lower than the lowest melting point and not higher than the melting point of other materials.

  The injection device according to the present invention includes a storage container having an injection hole, the stacked piezoelectric element according to any one of claims 1 to 15 stored in the storage container, and the injection by driving the stacked piezoelectric element. And a valve for ejecting liquid from the hole.

  Thus, the multilayer piezoelectric element of the present invention is formed by alternately laminating at least one piezoelectric body and a plurality of electrode layers so that the electrode layers partially face each other with the piezoelectric body in between. A piezoelectric body having a laminate, and having a pair of external electrodes for applying a voltage between the electrode layers on a side surface of the laminate, and providing a gap penetrating the electrode layer in the stacking direction of the laminate; Since the force restrained by the electrode layer is weakened when the electrode is deformed by an electric field, the piezoelectric body can be deformed relatively easily, the amount of displacement is improved, and the stress generated in the electrode layer is also reduced. It will be excellent. In addition, it is possible to provide an injection device having high reliability by mounting the multilayer piezoelectric element.

  In addition, the laminated piezoelectric element of the present invention is provided with a gap penetrating the electrode layer in all the electrode layers, so that the force restrained by the electrode layer when the piezoelectric body is deformed by an electric field is weakened, and displacement driving is performed. Since all the piezoelectric bodies to be deformed can be relatively easily deformed, the amount of displacement is further improved, and the stress generated in the electrode layer is also reduced, resulting in excellent durability. In addition, it is possible to provide an injection device having high reliability by mounting the multilayer piezoelectric element.

  Furthermore, the multilayer piezoelectric element of the present invention has a multilayer body in which at least one piezoelectric body and a plurality of electrode layers are alternately stacked, and the electrode layers are alternately disposed on the side surfaces of the multilayer body. In a laminated piezoelectric element that includes a pair of connected external electrodes and is driven by applying an electric field to the external electrodes, a void that occupies 5 to 70% of the area of the electrode layer is provided in the electrode layer. Therefore, when the piezoelectric body is deformed by an electric field, the force restrained by the electrode layer is weakened, the piezoelectric body can be deformed relatively easily, the displacement amount is improved, and the stress generated in the electrode layer is also reduced. It also has excellent durability. In addition, it is possible to provide an injection device having high reliability by mounting the multilayer piezoelectric element.

  Further, the maximum width of the gap in the electrode layer is set to 1 μm or more, or at the interface between the electrode portion and the gap in the electrode layer, the boundary between the electrode portion and the piezoelectric body, and the boundary between the gap and the electrode portion. By setting the angle to 60 degrees or more, the force with which the electrode layer restrains the piezoelectric body is reduced and the piezoelectric body is easily deformed. Therefore, the amount of displacement can be increased and the generated stress can be reduced. A jetting device having a laminated piezoelectric element excellent in the above can be provided.

  In addition to the above-described configuration, the metal composition in the electrode layer is mainly composed of a group 8-10 metal and / or a group 11 metal, and therefore has poor wettability with the ceramics constituting the piezoelectric body. The voids can be efficiently formed in the electrode layer, and even if the multilayer piezoelectric element is operated continuously, the migration phenomenon can be reduced, so that the durability is improved.

  1A and 1B show an embodiment of a laminated piezoelectric element of the present invention, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view. 2 is an enlarged view of a partial cross section near the electrode layer of the multilayer piezoelectric element of FIG.

  As shown in FIG. 1, the multilayer piezoelectric element 10 of the present invention is alternately arranged such that a plurality of electrode layers 2 sandwich a piezoelectric body 1 therebetween, and the electrode layers 2 are partially opposed to each other with the piezoelectric body 1 sandwiched therebetween. The laminated body formed by laminating is provided. Then, on the pair of opposed side surfaces of the laminate, the end portion where the electrode layer 2 is exposed and the pair of external electrodes 4 that are electrically connected every other layer are joined. Further, an inactive layer 9 is provided at both ends of the multilayer piezoelectric element 10. Here, when the multilayer piezoelectric element 10 of the present invention is used as a multilayer piezoelectric actuator, the lead wire 6 is connected and fixed to the external electrode 4 by soldering, and the lead wire 6 is connected to the external voltage supply unit. Good.

  Since the electrode layer 2 is made of a metal material such as silver-palladium, a predetermined voltage is applied to each piezoelectric body 1 through the electrode layer 2 to cause the piezoelectric body 1 to be displaced by the inverse piezoelectric effect.

  In the multilayer piezoelectric element 10 of the present invention, as a result of intensive studies by the inventor, as shown in FIG. 2, a gap 20 penetrating into the electrode layer 2 between the piezoelectric bodies 1 is provided. A gap 20 penetrating all the electrode layers 2 of the element 10 is provided. Further, when the penetrating gap 20 and the non-penetrating gap 21 are made to occupy 5 to 70% with respect to the area of the electrode layer 2, the displacement amount increases, and a laminated piezoelectric element having an excellent displacement amount can be obtained. Is the headline.

  In the conventional type that does not have the gap 20 that penetrates the electrode layer 2 and the gap 21 that does not penetrate, the piezoelectric body 1 is easily subjected to constraints from the electrode layer 2 when it is deformed by receiving an electric field. A sufficient amount of displacement of the multilayer piezoelectric element could not be obtained.

  On the other hand, in the laminated piezoelectric element having the gap 20 and the gap 21 not penetrating in the electrode layer 2 of the present invention, the piezoelectric body can be freely deformed, and the amount of deformation is larger than the conventional one.

  Here, the ratio (void ratio) of the gap to the area of the electrode layer 2 described above will be described. The porosity is measured on a surface obtained by cutting the multilayer piezoelectric element in the stacking direction. On the cut surface, the area of the voids existing in the electrode layer portion was measured, and the value obtained by dividing the sum of the void areas by the area of the electrode layer 2 (including voids) was multiplied by 100.

  On the other hand, when the porosity is less than 5%, when the piezoelectric body 1 is deformed by applying an electric field, the electrode layer 2 is constrained, the deformation of the piezoelectric body 1 is suppressed, and the deformation amount of the multilayer piezoelectric element is reduced. . Moreover, since the generated internal stress is increased, the durability is also adversely affected.

  On the other hand, if the porosity is larger than 70%, an extremely thin portion is formed in the electrode portion 2a between the voids 20 and 21, so that the strength of the electrode layer 2 itself is reduced, and the electrode layer 2 is liable to be cracked. Is not preferable because it may cause disconnection or the like. In addition, since the conductivity of the electrode layer 2 is lowered, it is difficult to apply a voltage to the piezoelectric body 1 and a sufficient amount of displacement may not be obtained.

  As shown in FIG. 2, the gaps 20 and 21 are not limited to those provided between the electrode portions 2a, but may exist in a state of being included in the electrode portion 2a.

  Furthermore, the porosity is more preferably 7 to 70%, and still more preferably 10 to 60%. By doing so, the piezoelectric body 1 can be deformed more smoothly, and the electrode layer 2 has sufficient conductivity, so that the displacement amount of the multilayer piezoelectric element 10 can be increased.

  Moreover, it is preferable that the maximum width in the cross section of the space | gap 20 and 21 is 1 micrometer or more. The maximum width described below is the measured value obtained by drawing the line parallel to the electrode and measuring the length of the gap in the cross section of the electrode layer in the cross section in the stacking direction of the multilayer piezoelectric element. The maximum value was taken as the maximum width. Furthermore, the maximum width of the gaps 20 and 21 is more preferably 2 μm, and further preferably 3 μm, from the viewpoint that the amount of displacement can be increased, internal stress is reduced, and durability is improved.

  Further, in the cross section of the electrode layer 2, the angle 24 formed by the tangent line 22 to the electrode portion 2 a starting from the portion where the interface between the electrode portion 2 a and the gaps 20, 21 contacts the piezoelectric body 1 and the piezoelectric body 1 is 60 degrees or more. Preferably there is. As shown in FIG. 2, the angle 24 is a line that starts from the point where the interface between the electrode portion 2a and the gap 2 is in contact with the piezoelectric body 1 and is in contact with the electrode portion 2a in the cross section in the stacking direction of the stacked piezoelectric element. Is expressed by an angle 24 formed by the tangent line 22 and the piezoelectric body 1.

  Here, when the angle 24 is less than 60 degrees, the portion of the meniscus formed by the electrode portion 2 a in the electrode layer 2 in contact with the piezoelectric body 1 becomes large, so that the force that the electrode layer 2 restrains the piezoelectric body 1 is large. Therefore, the displacement amount may be reduced. Furthermore, the angle 24 is more than 70 degrees from the viewpoint that the displacement amount can be increased because the force that the electrode layer 2 restrains the piezoelectric body 1 is reduced, the internal stress is reduced, and the durability is improved. Preferably, it is 80 degrees or more.

  Furthermore, it is desirable that the metal composition in the electrode layer 2 contains a group 8-10 metal and / or a group 11 metal as a main component. This is because the above metal composition has high heat resistance, so that the piezoelectric body 1 and the electrode layer 2 having a high firing temperature can be fired simultaneously. In addition, since the wettability with the piezoelectric body 1 is poor, voids are likely to be generated at the interface between the piezoelectric body 1 and the electrode layer 2, and when they are laminated and fired, the electrode layer 2 having a relatively high void is formed. be able to.

  Furthermore, when the metal composition in the electrode layer 2 is M1 (mass%) for the group 8-10 metal content and M2 (mass%) for the group 11 metal content, 0 <M1 ≦ 15, 85 ≦ It is preferable that the main component is a metal composition satisfying M2 <100 and M1 + M2 = 100. This is because when the group 8-10 metal exceeds 15% by mass, the specific resistance of the electrode layer 2 increases, and the electrode layer 2 may generate heat when the stacked piezoelectric element is continuously driven. Further, in order to suppress migration of the Group 11 metal in the electrode layer 2 to the piezoelectric body 1, the Group 8 to 10 metal content is preferably 0.001% by mass to 15% by mass. Further, in terms of improving the durability of the multilayer piezoelectric element 10, the content is preferably 0.1% by mass or more and 10% by mass or less. Moreover, when it is excellent in heat conduction and needs higher durability, 0.5 mass% or more and 10 mass% or less are more preferable. Further, when higher durability is required, it is more preferably 1% by mass or more and 8% by mass or less.

  Here, when the Group 11 metal is less than 85% by mass, the specific resistance of the electrode layer 2 increases, and when the multilayer piezoelectric element 10 is continuously driven, the electrode layer 2 may generate heat. Further, in order to suppress migration of the Group 11 metal in the electrode layer 2 to the piezoelectric body 1, the Group 11 metal is preferably 85 mass% or more and 99.999 mass% or less. Moreover, 90 mass% or more and 99.9 mass% or less are preferable at the point of improving the durability of the laminated piezoelectric element 10. Moreover, when higher durability is required, 90.5 mass% or more and 99.5 mass% or less are more preferable. Moreover, when higher durability is calculated | required, 92 to 98 mass% is further more preferable.

  The 8-10 group metal and 11 group metal which show the mass% of the metal component in said electrode layer 2 can be specified by analysis methods, such as EPMA (Electron Probe Micro Analysis) method.

  Furthermore, the metal component in the electrode layer 2 of the present invention is such that the group 8-10 metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, Os, and the group 11 metal is Cu, Ag, Preferably, at least one of Au is used. This is because the metal composition has excellent mass productivity in recent alloy powder synthesis techniques.

  Furthermore, as for the metal component in the electrode layer 2, it is preferable that a group 8-10 metal is at least 1 or more types among Pt and Pd, and a 11 group metal is at least 1 type or more among Ag and Au. Thereby, there is a possibility that the electrode layer 2 having excellent heat resistance and small specific resistance can be formed.

  Furthermore, as for the metal component in the electrode layer 2, it is preferable that group 11 metal is Cu. Thereby, there is a possibility that the electrode layer 2 excellent in thermal conductivity may be formed, and at the same time, the internal stress generated may be reduced.

  Furthermore, as for the metal component in the electrode layer 2, it is preferable that a group 8-10 metal is Ni. Thereby, the electrode layer 2 excellent in heat resistance may be formed.

  Moreover, it is preferable to add the material which comprises the said electrode layer, and an inorganic composition with bad wettability to the said electrode layer. This is because, since the electrode layer 2 has an inorganic composition with poor wettability, the electrode layer 2 has poor wettability during firing, so the electrode portion 2a around the inorganic composition is repelled and The portion without the electrode portion 2a, that is, the gaps 20 and 21 are formed, which is advantageous in terms of gap formation, and as a result, the amount of displacement can be improved. Here, as the inorganic composition, a material containing at least one of BN, TiN, and ZrN as a main component can be used. , 21 can be formed. An inorganic composition may be formed on the surface of the piezoelectric body 1, and forming the inorganic composition on the surface of the piezoelectric body 1 is advantageous in forming the void 20 penetrating the electrode layer 2.

Furthermore, it is preferable that the piezoelectric body 1 has a perovskite oxide as a main component. This is because, for example, when formed of a perovskite type piezoelectric ceramic material typified by barium titanate (BaTiO ₃ ) or the like, the piezoelectric strain constant d ₃₃ indicating the piezoelectric characteristics is high, so that the amount of displacement can be increased. Furthermore, the piezoelectric body 1 and the electrode layer 2 can be fired simultaneously. The piezoelectric body 1 described above preferably contains a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ having a relatively high piezoelectric strain constant d ₃₃ as a main component.

  Further, the electrode layer 2 whose end is exposed on the side surface of the laminate and the electrode layer 2 whose end is not exposed are alternately configured, and the piezoelectric layer 2 between the electrode layer 2 where the end is not exposed and the external electrode 4 is formed. It is preferable in terms of durability improvement that a groove is formed in the body 1 and that the groove is filled with an insulator having a Young's modulus lower than that of the piezoelectric body 1.

  Furthermore, it is preferable that a calcination temperature is 900 degreeC or more and 1050 degrees C or less. This is because when the firing temperature is 900 ° C. or lower, the firing temperature is low, so firing is insufficient, and it becomes difficult to manufacture the dense piezoelectric body 1. In addition, when the firing temperature exceeds 1050 ° C., the stress resulting from the difference between the contraction of the electrode layer 2 and the contraction of the piezoelectric body 1 during firing increases, and cracks may occur during continuous driving of the multilayer piezoelectric element 10. Because there is.

  Moreover, it is preferable that the deviation of the composition in the electrode layer 2 is 5% or less before and after firing. This is because when the compositional deviation in the electrode layer 2 exceeds 5% before and after firing, the metal material in the electrode layer 12 migrates to the piezoelectric body 11 and the expansion and contraction due to the driving of the multilayer piezoelectric element 10 is increased. Thus, the electrode layer 2 may not be able to follow.

  Here, the deviation of the composition in the electrode layer 2 indicates the rate of change in which the composition of the electrode layer 2 changes as the elements constituting the electrode layer 2 evaporate or diffuse into the piezoelectric body 1 by firing.

  In addition, the electrode layer 2 whose end is exposed on the side surface of the multilayer piezoelectric element 10 of the present invention and the electrode layer 2 whose end is not exposed are alternately configured, and the electrode layer 2 where the end is not exposed. A groove 3 is formed in a portion of the piezoelectric body 1 between the outer electrode 4 and the external electrode 4, and an insulator having a Young's modulus lower than that of the piezoelectric body 1 is preferably formed in the groove. Thereby, in such a laminated piezoelectric element 10, stress generated by displacement during driving can be relieved, and thus heat generation of the electrode layer 2 can be suppressed even when continuously driven.

  Further, as shown in FIG. 3, the external electrode 4 is preferably made of a porous conductor having a three-dimensional network structure. If the external electrode 4 is not composed of a porous conductor having a three-dimensional network structure, the external electrode 4 does not have flexibility and cannot follow the expansion and contraction of the laminated piezoelectric actuator. A contact failure between the external electrode 4 and the electrode layer 2 may occur. Here, the three-dimensional network structure does not mean a state in which a so-called spherical void exists in the external electrode 4, but the conductive material powder and the glass powder constituting the external electrode 4 are baked at a relatively low temperature. For this reason, voids exist in a state of being connected to some extent without completing the sintering, suggesting a state in which the conductive material powder and the glass powder constituting the external electrode 4 are three-dimensionally connected and joined.

  Alternatively, the porosity in the external electrode 4 is desirably 30 to 70% by volume. Here, the porosity is the ratio of the voids 4 a in the external electrode 4. This is because if the porosity in the external electrode 4 is smaller than 30% by volume, the external electrode 4 cannot withstand the stress generated by the expansion and contraction of the multilayer piezoelectric actuator, and the external electrode 4 may be disconnected. In addition, when the porosity in the external electrode 4 exceeds 70% by volume, the resistance value of the external electrode 4 increases, and thus when the large current is passed, the external electrode 4 may cause local heat generation and break. There is.

  The softening point (° C.) of the glass constituting the external electrode 4 is desirably 4/5 or less of the melting point (° C.) of the conductive material constituting the electrode layer 2. If the softening point of the glass constituting the external electrode 4 exceeds 4/5 of the melting point of the conductive material constituting the electrode layer 2, the softening point of the glass constituting the external electrode 4 and the electrode layer 2 are constituted. Since the melting point of the conductive material is about the same temperature, the temperature at which the external electrode 4 is baked inevitably approaches the melting point that forms the electrode layer 2, and therefore the electrode layer 2 and the external electrode 4 are baked when the external electrode 4 is baked. The conductive material aggregates to prevent diffusion bonding, and the baking temperature cannot be set to a temperature sufficient to soften the glass component of the external electrode 4, so that sufficient bonding strength with the softened glass cannot be obtained. There is a case.

  Furthermore, it is desirable that a glass rich layer is formed on the surface layer portion of the external electrode 4 on the piezoelectric body 1 side. This is because, if the glass-rich layer is not present, it is difficult to bond the glass component in the external electrode 4, so that there is a possibility that the external electrode 4 cannot easily be firmly bonded to the piezoelectric body 1.

  Furthermore, it is desirable that the glass constituting the external electrode 4 be amorphous. This is because, in crystalline glass, the external electrode 4 cannot absorb the stress generated by the expansion and contraction of the laminated piezoelectric actuator, so that cracks and the like may occur.

  Furthermore, it is desirable that the thickness of the external electrode 4 is thinner than the thickness of the piezoelectric body 1. This is because when the thickness of the external electrode 4 is larger than the thickness of the piezoelectric body 1, the strength of the external electrode 4 increases, so that the load on the joint between the external electrode 4 and the electrode layer 2 when the laminate 10 expands and contracts. May increase and contact failure may occur.

  Furthermore, it is desirable to provide a conductive auxiliary member 7 made of a conductive adhesive in which a metal mesh or a mesh-like metal plate is embedded on the outer surface of the external electrode 4. If the conductive auxiliary member 7 is not provided on the outer surface of the external electrode 4, the external electrode 4 cannot withstand the large current and is locally heated when driven by flowing a large current through the multilayer piezoelectric element 10. there's a possibility that.

  Further, if a mesh or a mesh-like metal plate is not used on the outer surface of the external electrode 4, the stress due to expansion and contraction of the multilayer piezoelectric element 10 directly acts on the external electrode 4, so that the external electrode 4 is laminated due to fatigue during driving. There is a possibility that peeling from the side surface of the piezoelectric element 10 becomes easy.

  Furthermore, it is desirable that the conductive adhesive is made of a polyimide resin in which conductive particles are dispersed. This is because the conductive adhesive has a high adhesive strength by using a polyimide resin having a relatively high heat resistance even when the laminated piezoelectric element 10 is driven at a high temperature by using the polyimide resin. Easy to maintain.

  Furthermore, it is desirable that the conductive particles are silver powder. This makes it easy to suppress local heat generation in the conductive adhesive by using silver powder having a relatively low resistance value for the conductive particles.

  In addition, the multilayer piezoelectric element 10 of the present invention is preferably composed of a single plate or one or more layers. As a result, the pressure applied to the element can be converted into a voltage, or the element can be displaced by applying a voltage to the element. Therefore, even if an unexpected stress is applied during element driving, the stress is reduced. Since the stress can be relieved by dispersing and converting the voltage, a highly reliable piezoelectric actuator having excellent durability can be provided.

  Next, the manufacturing method of the multilayer piezoelectric element 10 of the present invention will be described.

The multilayer piezoelectric element 10 according to the present invention includes a calcination powder of a perovskite oxide piezoelectric ceramic made of PbZrO ₃ —PbTiO ₃ or the like, a binder made of an acrylic or butyral organic polymer, and DOP ( A slurry that is mixed with a plasticizer such as dioctyl phthalate) or DBP (dibutyl phthalate) and within the above-mentioned range of impurities is prepared, and the slurry is formed by a tape molding method such as a known doctor blade method or calendar roll method. Thus, a ceramic green sheet to be the piezoelectric body 1 is manufactured, cut into an appropriate size, and fixed to the frame.

  Next, a conductive paste is prepared by adding and mixing a binder, a plasticizer and the like to the metal powder constituting the electrode layer 2 such as silver-palladium, and this is formed on the upper surface of each green sheet by screen printing or the like to 1 to 40 μm. Print to the thickness of. In this case, it is important to use two or more materials having different melting points so that the metal powder constituting the electrode layer has a void in the electrode layer 2 after firing, and the material may be a metal or an alloy. preferable. Then, when calcining at a temperature not lower than the lowest melting point of the metal or alloy constituting the electrode layer 2 and not higher than the melting point of the other metal, the melted metal or alloy exceeding the melting point is caused by capillary action in the electrode layer. Since it moves to a void | hole and the moved part turns into a space | gap, the electrode layer 2 which has the space | gap of this invention can be produced. The holes can be formed by, for example, a slight gap formed between the metal powders when the conductive paste is prepared, or a gap formed by debinding the binder portion.

  In addition, the gaps 20 and 21 may be formed by adding a material having poor wettability to the material constituting the electrode layer 2. Furthermore, the gaps 20 and 21 can also be formed by providing the material constituting the electrode layer 2 and the material having poor wettability on the green sheet surface on which the electrode layer 2 is printed.

  Next, similarly, a dummy layer containing a component serving as a sintering aid such as silver-palladium is printed on the upper surface of the green sheet by screen printing or the like to prepare a green sheet for the inactive layer 9.

  Then, a plurality of green sheets with conductive paste printed on the upper surface and green sheets for the inactive layer 9 are laminated so that the inactive layer 9 comes to the end of the laminated piezoelectric element, and are simultaneously brought into close contact with pressure. .

  Thereafter, the green sheet is cut into an appropriate size, debindered at a predetermined temperature, and then fired at 900 to 1050 ° C., whereby the multilayer piezoelectric element 10 is manufactured. During firing, the temperature of the metal or alloy constituting the electrode layer may be raised after being held at a temperature lower than the melting point of the second lowest metal or alloy that is higher than the melting point of the low melting point metal or alloy. is important.

  The multilayer piezoelectric element 10 is not limited to the one manufactured by the above manufacturing method, and may be formed by any manufacturing method as long as it is a method of creating a gap in the electrode layer.

  Thereafter, the electrode layer 2 whose end is exposed and the electrode layer 2 whose end is not exposed are alternately formed on the side surface of the multilayer piezoelectric element 10, and the gap between the electrode layer 2 where the end is not exposed and the external electrode 4 is formed. A groove 3 is formed in the piezoelectric body 1, and an insulator such as resin or rubber having a Young's modulus lower than that of the piezoelectric body 1 is formed in the groove 3. Here, the conductive material constituting the external electrode 4 is preferably silver having a low Young's modulus or an alloy containing silver as a main component from the viewpoint of sufficiently absorbing the stress generated by the expansion and contraction of the multilayer piezoelectric element 10.

In addition, a silver glass conductive paste is prepared by adding a binder to the glass powder, and this is formed into a sheet, and the green density of the dried (spattered solvent) is controlled to 6 to 9 g / cm ^3. Then, this sheet is transferred to the external electrode forming surface of the multilayer piezoelectric element 10 and is heated to a temperature higher than the softening point of the glass, a temperature not higher than the melting point of silver (965 ° C.) and a firing temperature (° C.) of 4 /. By baking at a temperature of 5 or less, the binder component in the sheet prepared using the silver glass conductive paste is scattered and disappeared, and the external electrode 4 made of a porous conductor having a three-dimensional network structure is formed. Can do.

  The baking temperature of the silver glass conductive paste effectively forms a neck portion, diffuses and joins the silver in the silver glass conductive paste and the electrode layer 2, and effectively creates voids in the external electrode 4. The temperature is preferably 550 to 700 ° C. from the viewpoint that the external electrode 4 and the side surface of the multilayer piezoelectric element 10 are partially bonded. The softening point of the glass component in the silver glass conductive paste is preferably 500 to 700 ° C.

  When the baking temperature is higher than 700 ° C., the sintering of the silver powder of the silver glass conductive paste proceeds so much that a porous conductor having an effective three-dimensional network structure cannot be formed, and the external electrode 4 Becomes too dense, and as a result, the Young's modulus of the external electrode 4 becomes too high to absorb the stress during driving sufficiently, and the external electrode 4 may be disconnected. Preferably, baking should be performed at a temperature within 1.2 times the softening point of the glass.

  On the other hand, when the baking temperature is lower than 550 ° C., since the diffusion bonding is not sufficiently performed between the end portion of the electrode layer 2 and the external electrode 4, the neck portion is not formed, and the electrode layer 2 and the external layer are driven during driving. There is a possibility of causing a spark between the electrodes 4.

  Note that the thickness of the silver glass conductive paste sheet is preferably thinner than the thickness of the piezoelectric body 1. More preferably, it is 50 μm or less from the viewpoint of following the expansion and contraction of the actuator.

  Next, the laminated piezoelectric element 10 on which the external electrode 4 is formed is immersed in a silicone rubber solution, and the silicone rubber solution is vacuum degassed to fill the groove 3 of the laminated piezoelectric element 10 with silicone rubber. Thereafter, the laminated piezoelectric element 10 is pulled up from the silicone rubber solution, and the side surface of the laminated piezoelectric element 10 is coated with silicone rubber. Thereafter, the silicone rubber coated inside the groove 3 and coated on the side surface of the columnar multilayer piezoelectric element 10 is cured to complete the multilayer piezoelectric element 10 of the present invention.

  Then, by connecting the lead wire 6 to the external electrode 4 and applying a direct current voltage of 0.1 to 3 kV / mm to the pair of external electrodes 4 via the lead wire 6 to polarize the piezoelectric layer 13, A multilayer piezoelectric actuator using the multilayer piezoelectric element 10 of the present invention is completed, and the lead wire 6 is connected to an external voltage supply unit, and a voltage can be applied to the electrode layer 2 via the lead wire and the external electrode 4. For example, each piezoelectric body 1 is greatly displaced by the inverse piezoelectric effect, and thereby functions as an automobile fuel injection valve for injecting and supplying fuel to the engine, for example.

  Further, as shown in FIG. 3, a conductive auxiliary member 7 made of a conductive adhesive in which a metal mesh or a mesh-like metal plate is embedded may be formed on the outer surface of the external electrode 4. In this case, by providing a conductive auxiliary member 7 on the outer surface of the external electrode 4, a large current can be supplied to the conductive auxiliary member 7 even when a large current is input to the actuator and driven at high speed. Because the current flowing through the external electrode 4 can be reduced, it is possible to prevent the external electrode 4 from causing local heat generation and disconnection, and the durability can be greatly improved. Furthermore, since a metal mesh or a mesh-like metal plate is embedded in the conductive adhesive, it is possible to prevent the conductive adhesive from cracking.

  The metal mesh is a braided metal wire, and the mesh metal plate is a mesh formed by forming holes in a metal plate.

  Further, the conductive adhesive constituting the conductive auxiliary member 7 is preferably made of a polyimide resin in which silver powder is dispersed. That is, by dispersing silver powder having a low specific resistance in a polyimide resin having a high heat resistance, the conductive auxiliary member 7 having a low resistance value and a high adhesive strength can be formed even when used at a high temperature. it can. More preferably, the conductive particles are non-spherical particles such as flakes or needles. This is because the entanglement between the conductive particles can be strengthened by making the shape of the conductive particles non-spherical particles such as flakes and needles, and the shear strength of the conductive adhesive can be further increased. This is because it can be increased.

  The laminated piezoelectric element 10 of the present invention is not limited to these, and various modifications can be made without departing from the gist of the present invention.

  Moreover, although the example which formed the external electrode 4 in the side surface which the laminated piezoelectric element 10 opposes above was demonstrated, in this invention, you may form a pair of external electrode in the adjacent side surface, for example.

  FIG. 4 shows an injection device of the present invention. An injection hole 33 is provided at one end of the storage container 31, and a needle valve 35 that can open and close the injection hole 33 is stored in the storage container 31. Has been.

  A fuel passage 37 is provided in the injection hole 33 so as to be able to communicate. The fuel passage 37 is connected to an external fuel supply source, and fuel is always supplied to the fuel passage 37 at a constant high pressure. Therefore, when the needle valve 35 opens the injection hole 33, the fuel supplied to the fuel passage 37 is formed to be injected into a fuel chamber (not shown) of the internal combustion engine at a constant high pressure.

  Further, the upper end portion of the needle valve 35 has a large diameter, and serves as a piston 41 slidable with a cylinder 39 formed in the storage container 31. In the storage container 31, the piezoelectric actuator 43 described above is stored.

  In such an injection device, when the piezoelectric actuator 43 is extended by applying a voltage, the piston 41 is pressed, the needle valve 35 closes the injection hole 33, and the supply of fuel is stopped. When the application of voltage is stopped, the piezoelectric actuator 43 contracts, the disc spring 45 pushes back the piston 41, and the injection hole 33 communicates with the fuel passage 37 so that fuel is injected.

  Further, the present invention relates to the multilayer piezoelectric element 10 and the injection device, but is not limited to the above-described embodiments, and includes, for example, a fuel injection device for an automobile engine, a liquid injection device such as an ink jet, an optical device, and the like. Drive elements mounted on precision positioning devices, vibration prevention devices, etc., or sensor elements mounted on combustion pressure sensors, knock sensors, acceleration sensors, load sensors, ultrasonic sensors, pressure sensitive sensors, yaw rate sensors, etc., and Needless to say, elements other than circuit elements mounted on a piezoelectric gyro, a piezoelectric switch, a piezoelectric transformer, a piezoelectric breaker, etc. can be implemented as long as the elements use piezoelectric characteristics.

  A multilayer piezoelectric actuator comprising the multilayer piezoelectric element of the present invention was produced as follows.

(Experimental example) First, a slurry in which a calcined powder of a piezoelectric ceramic mainly composed of lead zirconate titanate (PbZrO ₃ -PbTiO ₃ ), a binder, and a plasticizer is prepared, and is 150 μm thick by a doctor blade method. A ceramic green sheet to be the piezoelectric body 1 was produced.

  On one side of this ceramic green sheet, a conductive paste obtained by adding a binder to a silver-palladium alloy formed at an arbitrary composition ratio was printed to a thickness of 4 μm by screen printing. These sheets were prepared for a 300-sheet laminate. Separately, green sheets that serve as protective layers were prepared, and these were laminated from the bottom to 30 protective layers, 300 laminates, 30 protective layers, pressed, degreased, and the melting point of Ag. After the temperature was once maintained as described above, final baking was performed at 1000 ° C. In addition to this, BN was added to a conductive paste obtained by adding a binder to Ag, and an electrode layer 2 having a relatively large ratio of the voids 20 and 21 was obtained through the same process. Further, a conductive paste obtained by adding a binder to Cu and a conductive paste obtained by adding a binder to Ni were similarly printed to a thickness of 4 μm by a screen printing method. These sheets were prepared for a 300-sheet laminate. Separately, green sheets that serve as protective layers are prepared, and these are laminated from the bottom to 30 protective layers, 300 laminates, and 30 protective layers, pressed, degreased, and each conductive layer. The temperature was once maintained above the melting point of the metal contained in the adhesive paste, and then further heated and finally fired.

  Thereafter, a groove having a depth of 50 μm and a width of 50 μm was formed at every other end of the electrode layer 2 on the side surface of the laminate by a dicing apparatus.

Next, a mixture of 90% by volume of flaky silver powder having an average particle diameter of 2 μm and 10% by volume of amorphous glass powder having a remaining softening point of 640 ° C. mainly composed of silicon having an average particle diameter of 2 μm. In addition, 8 parts by mass of the binder was added to 100 parts by mass of the total mass of the silver powder and the glass powder, and mixed sufficiently to prepare a silver glass conductive paste. The silver glass conductive paste thus produced was formed on a release film by screen printing, dried and then peeled off from the release film to obtain a sheet of silver glass conductive paste. When the raw density of this sheet was measured by Archimedes method, it was 6.5 g / cm ³ And the sheet of silver glass paste was transferred to the external electrode surface of the laminate and baked at 650 ° C. for 30 minutes, An external electrode 4 made of a porous conductor having a three-dimensional network structure was formed. The porosity of the external electrode 4 at this time was 40% when measured using an image analysis device for a cross-sectional photograph of the external electrode 4.

  Thereafter, a lead wire is connected to the external electrode 4, a 3 kV / mm direct current electric field is applied to the positive and negative external electrodes via the lead wire for 15 minutes, and polarization treatment is performed. As shown in FIG. A multilayer piezoelectric actuator using the element was produced.

  As a result of applying a DC voltage of 170 V to the obtained multilayer piezoelectric element, a displacement amount as shown in Table 1 was obtained. Furthermore, a drive test was performed by applying an AC voltage of 0 to +170 V at a frequency of 150 Hz to the multilayer piezoelectric element at room temperature.

The multilayer piezoelectric element performs a continuous test up to 1 × 10 ⁹ times of driving. At that time, a DC voltage of 170 V is applied to the multilayer piezoelectric element, the displacement is measured, and before and after the driving test. The change in displacement was calculated. The change in the amount of displacement before and after the driving test was obtained by dividing the absolute value of the difference between the displacement before and after the driving test by the amount of displacement before the driving test and multiplying by 100.

  The porosity, the maximum width of the void, and the angle were measured as follows.

The porosity was measured on a plane obtained by cutting the multilayer piezoelectric element in the stacking direction. On the cut surface, the area of the voids 20 and 21 existing in the electrode layer 2 is measured, and the value obtained by dividing the sum of the areas of the voids 20 and 21 by the area of the electrode layer 2 (including voids) is multiplied by 100 It is. The measurement was performed at five or more arbitrary locations, and the average value was defined as the porosity. In addition, the maximum width is obtained by drawing a line parallel to the electrode and measuring the length of the gaps 20 and 21 existing in the cross section of the electrode layer 2 in the cross section in the stacking direction of the multilayer piezoelectric element 10. The maximum measured value was taken as the maximum width. The measurement was performed at arbitrary 10 locations, and the largest thing was taken as the maximum width from all the results. Finally, starting from the portion where the interface between the electrode portion 2a and the gap 20 in the electrode layer 2 is in contact with the piezoelectric body 1, the angle 24 formed by the tangent line from the starting point to the electrode portion 2a and the piezoelectric body 1 is measured as In the cross section in the stacking direction of the type piezoelectric element 10, arbitrary 10 angles were measured at arbitrary 10 locations, and the average value was calculated and shown as a representative value. The results are shown in Table 1.

  From the table, sample No. which is a comparative example. No. 1 has no through-hole in the electrode layer 2 and the porosity is less than 5%. Therefore, the force with which the electrode layer 2 restrains the piezoelectric body 1 is increased. The change rate of the displacement amount before and after the driving test was 1.1%, and the durability was also lowered. Sample No. 9, since the porosity of the electrode layer 2 exceeded 70%, a desired voltage could not be applied to the piezoelectric body 1, and the initial displacement decreased, and when continuously driven, the strength of the electrode layer 2 decreased. Durability also decreased.

  In contrast to these, the sample No. 1 of the present invention has voids penetrating the electrode layer 2 and further has voids 20 and 21 of 5 to 70%. Nos. 2 to 8 and 10 to 38 have an initial displacement amount of 48 μm or more and comparative example No. It was found that the displacement amount was larger than those of 1 and 9, and the laminate type piezoelectric element 10 was excellent. In addition, Sample No. Nos. 2 to 8 and 10 to 38 have a change rate of the displacement amount before and after the continuous driving test of 0.8% or less, and Comparative Example No. It was found that the product of the present invention was superior in terms of durability as well as being smaller than 1 and 9.

  In particular, the maximum width of the gaps 20 and 21 is 1 μm or more, or the part where the interface between the electrode part 2a and the gap 20 in the electrode layer 2 is in contact with the piezoelectric body 1, and the tangent line from the starting point to the electrode part 2a and the piezoelectric body Sample No. 1 in which the angle 24 formed with No. 1 is 60 degrees or more. 3 to 8, 10 to 19, and 21 to 38 have a large initial displacement amount of 50 μm or more, and a small change rate of 0.6% or less before and after the continuous driving test. It was found that the durability was also excellent.

The laminated piezoelectric element of this invention is shown, (a) is a perspective view, (b) is sectional drawing. It is an expanded sectional view of the electrode layer distribute | arranged between the piezoelectric materials of the multilayer piezoelectric element of this invention. The modification of the lamination type piezoelectric element of the present invention is shown, (a) is a perspective view and (b) is a sectional view. It is explanatory drawing which shows the injection apparatus of this invention. 1 shows a conventional multilayer piezoelectric element, where (a) is a sectional view and (b) is an enlarged sectional view in the vicinity of an electrode layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric body 2 ... Electrode layer 2a ... Electrode part 3 ... Groove 4 ... External electrode 6 ... Lead wire 7 ... Conductive auxiliary member 9 ... Inactive layer DESCRIPTION OF SYMBOLS 10 ... Stacking-type piezoelectric element 20 ... Penetration space | gap 21 ... Space | gap 22 ... Tangent line to the electrode layer from the part where the interface of an electrode layer and a space | gap contacts a piezoelectric material 24 ... Angle formed by the tangent to the electrode layer starting from the portion where the interface between the electrode layer and the gap contacts the piezoelectric body and the piezoelectric body 31... Storage container 33... Injection hole 35. DESCRIPTION OF SYMBOLS 51 ... Piezoelectric body 52 ... Electrode layer 53 ... Multilayer piezoelectric element 54 ... External electrode 55 ... Inactive layer 56 ... Lead wire 61 ... Insulating layer

Claims (18)

It has a laminated body in which at least one piezoelectric body and a plurality of electrode layers are alternately laminated so that the electrode layers partially face each other with the piezoelectric body in between, and on the side surface of the laminated body, A multilayer piezoelectric element comprising a pair of external electrodes for applying a voltage between the electrode layers, wherein a gap penetrating the electrode layer is provided in the lamination direction of the multilayer body. The multilayer piezoelectric element according to claim 1, wherein a gap penetrating the electrode layer is provided in all the electrode layers. It has a laminated body in which at least one piezoelectric body and a plurality of electrode layers are alternately laminated so that the electrode layers partially face each other with the piezoelectric body in between, and on the side surface of the laminated body, In the laminated piezoelectric element comprising a pair of external electrodes for applying a voltage between the electrode layers, a gap occupying 5 to 70% of the area of the electrode layer is provided in the electrode layer. Type piezoelectric element. 4. The multilayer piezoelectric element according to claim 1, wherein the electrode layers are electrically connected by being alternately connected to the pair of external electrodes with the piezoelectric body interposed therebetween. 5. The multilayer piezoelectric element according to claim 1, wherein the electrode layer has a thickness of 0.1 to 10 μm. The angle formed by the boundary between the electrode part and the piezoelectric body and the boundary between the gap and the electrode part at the interface between the electrode part and the gap in the electrode layer is 60 degrees or more. The laminated piezoelectric element according to any one of 1 to 5. The multilayer piezoelectric element according to claim 1, wherein the metal composition in the electrode layer contains a group 8-10 metal and / or a group 11 metal as a main component. When the content of the group 8-10 metal in the electrode layer is M1 (mass%) and the content of the group 11 metal is M2 (mass%), 0 <M1 ≦ 15, 85 ≦ M2 <100, M1 + M2 = The multilayer piezoelectric element according to claim 7, wherein 100 is satisfied. The Group 8-10 metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the Group 11 metal is at least one of Cu, Ag, and Au. The multilayer piezoelectric element according to claim 7 or 8. The group 8-10 metal is at least one of Pt and Pd, and the group 11 metal is at least one of Ag and Au. Multilayer piezoelectric element. The multilayer piezoelectric element according to claim 7, wherein the group 8-10 metal is Cu. The multilayer piezoelectric element according to claim 7, wherein the group 8-10 metal is Ni. The multilayer piezoelectric element according to any one of claims 1 to 12, wherein an inorganic composition containing at least one of BN, TiN, and ZrN as a main component is added to the electrode layer. The multilayer piezoelectric element according to claim 1, wherein the piezoelectric body contains a perovskite oxide as a main component. 15. The multilayer piezoelectric element according to claim 14, wherein the piezoelectric body is mainly composed of a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ . A groove is formed in the piezoelectric body at a portion where the electrode layer and the external electrode are insulated by the piezoelectric body, and the groove is filled with an insulator having a Young's modulus lower than that of the piezoelectric body. The multilayer piezoelectric element according to claim 1. It has a laminated body in which at least one piezoelectric body and a plurality of electrode layers are alternately laminated so that the electrode layers partially face each other with the piezoelectric body in between, and on the side surface of the laminated body, In the method of manufacturing a laminated piezoelectric element having a pair of external electrodes for applying a voltage between the electrode layers, the electrode layer is composed of two or more kinds of mixed materials, and the mixed material has the lowest melting point or higher and the other A method for producing a multilayer piezoelectric element comprising a step of calcining at a temperature not higher than the melting point of the material, followed by a main firing. A storage container having an injection hole, the multilayer piezoelectric element stored in the storage container, and a valve that ejects liquid from the injection hole by driving the multilayer piezoelectric element. An injection device comprising:

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