JP2005150369A - Laminated piezoelectric element and spraying device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated piezoelectric element which has excellent durability and high reliability without malfunction of an apparatus since a desired displacement is not effectively changed even by continuously driving. <P>SOLUTION: In the laminated piezoelectric element obtained by alternately laminating piezoelectric elements and electrodes, a metal composition in an internal electrode contains a group VIII metal and a group Ib metal as main ingredients, in such a manner that when the content of the group VIII metal in the electrode is M1 wt% and the content of the group Ib metal is M2 wt%, 0<M1≤15, 85≤M2<100, and M1+M2=100 are satisfied. <P>COPYRIGHT: (C)2005,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.

  Conventionally, as a multilayer piezoelectric element, a multilayer piezoelectric actuator in which piezoelectric bodies and electrodes are alternately stacked is known. Multilayer piezoelectric actuators are classified into two types: simultaneous firing types and stack types in which piezoelectric ceramics and internal electrode plates are alternately stacked. Considering low voltage and manufacturing cost reduction, the layered piezoelectric actuator is thinned. Therefore, a co-fired multilayer piezoelectric actuator is showing an advantage.

FIG. 2 shows a typical multilayer capacitor as a conventional multilayer electronic component, in which dielectrics 21 and internal electrodes 22 are alternately stacked. Internal electrodes 22 are formed on the entire main surface of dielectric 21. This is not a partial electrode structure. Internal electrode 22 of this partial electrode structure
Are alternately stacked, so that the internal electrodes 22 can be alternately connected to the external electrodes 23 formed on the side surface of the multilayer electronic component every other layer (see, for example, Patent Document 1).

  FIG. 1 shows a conventional multilayer piezoelectric element, in which piezoelectric bodies 11 and internal electrodes 12 are alternately stacked. However, the internal electrodes 12 are not formed on the entire main surface of the piezoelectric body 11 and are so-called. It has a partial electrode structure. By laminating the internal electrodes 12 of this partial electrode structure alternately on the left and right, the internal electrodes 12 can be alternately connected to the external electrodes 15 formed on the side surface of the multilayer electronic component. The basic structure is the same as that of the multilayer capacitor of FIG. 2, and an internal electrode paste is printed on a ceramic green sheet in a pattern having a predetermined electrode structure, and a plurality of green sheets coated with the internal electrode paste are laminated to form a multilayer laminate. Was produced and fired to produce a laminate (see, for example, Patent Document 2).

  In such a laminated piezoelectric element, piezoelectric bodies 11 and internal electrodes 12 are alternately laminated to form a columnar laminated body 13, and inactive layers 14 are laminated on both end faces in the laminating direction. The internal electrode 12 is formed so that one end thereof is electrically connected to the external electrode 15 alternately on the left and right sides. When used as a multilayer piezoelectric actuator, a lead wire may be further fixed to the external electrode 15 with solder.

  Further, as the internal electrode, an alloy of silver and palladium is used. Further, in order to simultaneously fire the piezoelectric body and the internal electrode, the metal composition of the internal electrode is 70% by weight of silver and 30% by weight of palladium. (For example, see Patent Document 3).

This is a piezoelectric body mainly composed of a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ with a solidus of 1150 ° C. and a liquidus of 1220 ° C. in a composition of 70% by weight of silver and 30% by weight of palladium. This is because the optimum sintering temperature was around 1200 ° C.

  As described above, an internal electrode made of a metal composition containing a silver / palladium alloy containing palladium is used instead of an internal electrode made of a metal composition containing 100% silver. This is because when a potential difference is applied between the electrodes, a so-called silver migration phenomenon occurs in which silver in the electrode moves along the element surface from the positive electrode to the negative electrode of the pair of electrodes. This phenomenon occurs particularly remarkably in a high temperature and high humidity atmosphere.

By the way, in recent years, in order to ensure a large amount of displacement under a large pressure with a small piezoelectric actuator, a higher electric field is applied to continuously drive for a long time.
Japanese Utility Model Publication No. 60-99522 JP-A-61-133715 Japanese Utility Model Publication No. 1-130568

  However, since the piezoelectric body has a characteristic that the amount of displacement changes depending on the environmental temperature to be used, there is a problem that the amount of displacement of the piezoelectric actuator changes as the element temperature rises. In addition, a change in the displacement amount during driving causes a load fluctuation with respect to the power source for voltage control, which causes a problem of placing a burden on the power source. Furthermore, when the rate of change of the displacement amount is large, not only the displacement amount itself deteriorates but also there is a problem that when the device temperature rise exceeds the heat dissipation amount, a thermal runaway phenomenon occurs and the device is destroyed.

  Therefore, attempts have been made to increase the composition ratio of silver in order to make the internal electrode have a low specific resistance composition. However, the electrode resistance value is increased to a high resistance because the electrode structure cannot be made dense. There was a problem.

  In other words, the composition of 70% by weight of silver and 30% by weight of palladium that has been used in conventional multilayer piezoelectric elements has a high resistance characteristic 1.5 times that of palladium. In addition, if the sintered density of the internal electrode is lowered, the electrode has a higher resistance.

  In addition, in such a multilayer piezoelectric element, when the piezoelectric actuator is driven, the desired amount of displacement gradually changes, causing a problem that the device malfunctions. And there was a need for improved durability.

  It is an object of the present invention to provide a multilayer piezoelectric element and a jetting device that are excellent in durability and do not change in displacement even when a piezoelectric actuator is continuously driven for a long time under high voltage and high pressure. And

  The multilayer piezoelectric element of the present invention has a multilayer body in which at least one piezoelectric body and a plurality of internal electrodes are alternately stacked, and the internal electrodes are alternately connected to the side surface of the multilayer body every other layer. In the laminated piezoelectric element that includes a pair of external electrodes and is driven by applying an electric field to the external electrodes, the metal composition in the internal electrodes is mainly composed of a group VIII metal and a group lb metal in the periodic table, When the content of the group VIII metal is M1 (wt%) and the content of the group Ib metal is M2 (wt%), 0 <M1 ≦ 15, 85 ≦ M2 <100, and M1 + M2 = 100 are satisfied. Features.

  As a result, in such a multilayer piezoelectric element, the specific resistance of the internal electrode can be reduced, so that heat generation of the internal electrode portion can be suppressed even when continuously driven. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided. At the same time, even when continuously driven, a silver migration phenomenon does not occur, and a highly reliable piezoelectric actuator having excellent durability can be provided even in a high temperature and high humidity atmosphere.

  In the multilayer piezoelectric element of the present invention, the group VIII metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the group Ib metal is at least one of Cu, Ag, and Au. It is characterized by more than seeds.

  Thereby, in such a laminated piezoelectric element, the raw material for the internal electrode can be any of the alloy raw material and the mixed powder raw material, and the specific resistance of the internal electrode can be reduced. Heat generation in the internal electrode portion can be suppressed. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  In the multilayer piezoelectric element of the present invention, the group VIII metal is at least one of Pt and Pd, and the group Ib metal is at least one of Ag and Au.

  Accordingly, in such a multilayer piezoelectric element, an electrode having excellent heat resistance can be formed and the specific resistance of the internal electrode can be reduced. Therefore, even when continuously driven, the heat generation of the internal electrode portion can be suppressed. . Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  At the same time, such a multilayer piezoelectric element can relieve stress caused by displacement during driving, and can form an electrode having excellent heat resistance, oxidation resistance and thermal conductivity, and the ratio of internal electrodes. Since the resistance can be reduced, it is possible to suppress the heat generation of the internal electrode portion even if it is continuously driven. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  In the multilayer piezoelectric element of the present invention, the group Ib metal is Cu.

  As a result, in such a multilayer piezoelectric element, an electrode having excellent heat conduction characteristics can be formed, and the specific resistance of the internal electrode can be reduced. Therefore, even when continuously driven, the heat generation of the internal electrode portion can be suppressed. it can. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  In addition, the multilayer piezoelectric element of the present invention includes a multilayer body in which at least one piezoelectric body and a plurality of internal electrodes are alternately stacked, and the internal electrodes are alternately disposed on the side surfaces of the multilayer body. In a laminated piezoelectric element comprising a pair of connected external electrodes and driven by applying an electric field to the external electrodes, the element resistance when the metal composition component in the internal electrode is made of silver is ρAg, the metal composition When the element resistance when the physical component is made of palladium is ρPd, the element resistance ρ satisfies ρAg <ρ <ρPd.

  Accordingly, in such a multilayer piezoelectric element, an electrode having excellent heat resistance can be formed and the specific resistance of the internal electrode can be reduced. Therefore, even when continuously driven, the heat generation of the internal electrode portion can be suppressed. . Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  In addition, the multilayer piezoelectric element of the present invention includes a multilayer body in which at least one piezoelectric body and a plurality of internal electrodes are alternately stacked, and the internal electrodes are alternately disposed on the side surfaces of the multilayer body. In a laminated piezoelectric element having a pair of connected external electrodes and driven by applying an electric field to the external electrodes, the electrical conductivity of the internal electrodes when the metal composition component in the internal electrodes is made of silver is represented by σAg When the internal electrode conductivity when the metal composition component is palladium is σPd, the internal electrode conductivity σ is σPd <σ <σAg.

  Accordingly, in such a multilayer piezoelectric element, an electrode having excellent heat resistance can be formed and the specific resistance of the internal electrode can be reduced. Therefore, even when continuously driven, the heat generation of the internal electrode portion can be suppressed. . Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  In addition, the multilayer piezoelectric element of the present invention includes a multilayer body in which at least one piezoelectric body and a plurality of internal electrodes are alternately stacked, and the internal electrodes 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, the maximum diameter of crystal grains made of a metal composition component that constitutes the internal electrodes is 1 μm or more. Is characterized by the presence of more than 80% by volume of the metal composition.

  As a result, in such a multilayer piezoelectric element, the specific resistance of the internal electrode can be reduced, so that heat generation of the internal electrode portion can be suppressed even when continuously driven. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  The multilayer piezoelectric element of the present invention is characterized in that an inorganic composition is added to the internal electrode together with a metal composition.

  Thereby, in such a multilayer piezoelectric element, the internal electrode and the piezoelectric body can be firmly coupled, and heat generation of the internal electrode portion can be suppressed even when continuously driven. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

The inorganic composition is mainly composed of a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ .

  Thereby, in such a multilayer piezoelectric element, the internal electrode and the piezoelectric body can be firmly coupled, and heat generation of the internal electrode portion can be suppressed even when continuously driven. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  Further, the piezoelectric body is mainly composed of a perovskite oxide.

  Thus, in such a multilayer piezoelectric element, the piezoelectric body and the internal electrode can be fired simultaneously, and the specific resistance of the internal electrode can be reduced. Therefore, even when continuously driven, the heat generation of the internal electrode portion is suppressed. be able to. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

Further, the piezoelectric material is mainly composed of a perovskite oxide made of PbZrO ₃ —PbTiO ₃ .

  Thus, in such a multilayer piezoelectric element, the amount of displacement can be increased and the specific resistance of the internal electrode can be reduced. Therefore, even when continuously driven, heat generation in the internal electrode portion can be suppressed. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  Moreover, the firing temperature of the laminate is 900 ° C. or higher and 1000 ° C. or lower. Thereby, since the piezoelectric body and the electrode can be firmly coupled, a highly reliable piezoelectric actuator having excellent durability can be provided.

  Further, the composition deviation in the internal electrode is 5% or less before and after firing. Thereby, since it can suppress that an electrode becomes hard, the highly reliable piezoelectric actuator excellent in durability can be provided.

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

  Thereby, in such a multilayer piezoelectric element, stress generated by displacement during driving can be relieved, so that heat generation of the internal electrode portion can be suppressed even when continuously driven. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  The injection device of the present invention includes a storage container having an injection port, a multilayer piezoelectric element stored in the storage container, and a valve that ejects liquid from the injection hole by driving the multilayer piezoelectric element. It is characterized by becoming. In the injection device, as described above, even if it is continuously driven in the multilayer piezoelectric element, the desired displacement does not change effectively, so that the device does not malfunction and has high durability and high reliability. Can be provided.

  According to such a laminated piezoelectric element of the present invention, the laminated piezoelectric element has a laminated body in which at least one piezoelectric body and a plurality of internal electrodes are alternately laminated, and the internal electrodes are arranged on one side of the laminated body. A laminated piezoelectric element having a pair of external electrodes alternately connected to each other and driven by applying an electric field to the external electrodes, wherein the metal composition in the internal electrodes is a group VIII metal and a group Ib metal in the periodic table As the main component, when the content of the group VIII metal is M1 (wt%) and the content of the group Ib metal is M2 (wt%), 0 <M1 ≦ 15, 85 ≦ M2 <100, M1 + M2 = 100 By satisfying the above, since it is possible to suppress an increase in the element temperature even if it is continuously driven, the desired amount of displacement does not change effectively, so that the device does not malfunction and further there is no thermal runaway. High reliability with excellent durability It is possible to provide a gender of the piezoelectric actuator.

  According to such a laminated piezoelectric element of the present invention, the laminated piezoelectric element has a laminated body in which at least one piezoelectric body and a plurality of internal electrodes are alternately laminated, and the internal electrodes are arranged on one side of the laminated body. In the laminated piezoelectric element having a pair of external electrodes alternately connected to each other and driven by applying an electric field to the external electrodes, the element resistance when the metal composition component in the internal electrode is made of silver is ρAg When the element resistance when the metal composition component is palladium is ρPd, since the element resistance ρ is ρAg <ρ <ρPd, an increase in the element temperature can be suppressed even when continuously driven. Therefore, since the desired amount of displacement does not change effectively, it is possible to provide a highly reliable piezoelectric actuator that is superior in durability without causing malfunction of the apparatus and without thermal runaway.

  According to such a laminated piezoelectric element of the present invention, the laminated piezoelectric element has a laminated body in which at least one piezoelectric body and a plurality of internal electrodes are alternately laminated, and the internal electrodes are arranged on one side of the laminated body. In a laminated piezoelectric element comprising a pair of external electrodes connected alternately to each other and driven by applying an electric field to the external electrodes, the conductivity of the internal electrodes when the metal composition component in the internal electrodes is made of silver When the internal electrode conductivity σ is σPd <σ <σAg when the rate is σAg and the internal electrode conductivity when the metal composition component is palladium is σPd, the element temperature Since the desired displacement does not change effectively, the device does not malfunction, and further provides a highly reliable piezoelectric actuator with excellent durability without thermal runaway. be able to

  Furthermore, since the desired amount of displacement does not change effectively even when the multilayer piezoelectric element is continuously driven, a highly reliable injection device having excellent durability without causing malfunction of the device is provided. Can do.

  The multilayer piezoelectric element of the present invention will be described in detail below. 1A and 1B show an embodiment of a laminated piezoelectric element according to the present invention. FIG. 1A is a perspective view, and FIG. 1B is a perspective development view showing a laminated state of a piezoelectric layer and an internal electrode layer.

  In the laminated piezoelectric element, piezoelectric bodies 11 and internal electrodes 12 are alternately laminated to form a columnar laminated body 13, and inactive layers 14 are laminated on both end surfaces in the laminating direction.

  External electrodes 15 are joined to opposite side surfaces of the columnar laminate 13, and the laminated internal electrodes 12 are electrically connected to the external electrodes 15 every other layer. The external electrode 15 has a function of commonly supplying a voltage necessary for displacing the piezoelectric body 11 to each connected internal electrode 12 by the reverse piezoelectric effect.

  Furthermore, when used as a multilayer piezoelectric actuator, the lead wire may be connected and fixed to the external electrode 15 by solder. The lead wire serves to connect the external electrode 15 to an external voltage supply unit.

  Conventionally, in order to keep the element displacement amount during continuous driving constant, a method of keeping the element temperature constant during continuous driving or fine control of the driving voltage according to the element temperature has been used. Specifically, in order to control the drive voltage while monitoring the element temperature, or to control the temperature around the element, a structure with a heat sink that actively dissipates heat is used. In the present invention, it is preferable to reduce the element resistance for the purpose of suppressing the heat generation of the element itself generated by driving.

  In particular, in order to reduce the element resistance, it is preferable to reduce the specific resistance value of the internal electrode or to use a material having excellent thermal conductivity as the electrode material.

  Further, in order to efficiently transfer the heat inside the element to the outside of the element, it is preferable that the internal electrode itself for transferring the heat to the outside of the element uses a material having excellent heat conduction characteristics. Furthermore, it is preferable that the internal electrode itself is exposed to the outside of the element. Furthermore, since it is desirable that the temperature characteristic of the displacement amount of the piezoelectric material itself is constant regardless of the operating temperature, a piezoelectric material having a small displacement amount with respect to a change in element temperature during continuous driving is preferable. .

  To reduce the resistance value of the electrode material means to use a material having a small specific resistance as the electrode material, and to make a dense electrode structure in which a path of electrical conduction is ensured.

  In the multilayer piezoelectric element of the present invention, the metal composition in the internal electrode 12 is mainly composed of a Group VIII metal and a Group Ib metal. Since the metal composition has heat resistance, the piezoelectric body 11 and the internal electrode 12 can be fired simultaneously.

  When the group VIII metal content is M1 (% by weight) and the group Ib metal content is M2 (% by weight), 0 <M1 ≦ 15, 85 ≦ M2 <100, and M1 + M2 = 100 are satisfied. Let it be a metal composition.

  The reason why the composition ratio of the main component of the internal electrode metal component of the present invention is limited to the above range is as follows. That is, if the group VIII metal exceeds 15% by weight, the specific resistance of the internal electrode 12 increases, and the internal electrode 12 may generate heat when the laminated piezoelectric element is continuously driven. Further, in order to suppress migration of the group Ib metal in the internal electrode 2 to the piezoelectric body 11, the group VIII metal is preferably made 0.001 wt% or more and 15 wt% or less. Further, from the viewpoint of improving the durability of the multilayer piezoelectric element, it is preferably 0.1% by weight or more and 10% by weight or less. Moreover, when it is excellent in heat conduction and higher durability is required, 0.5 wt% or more and 9.5 wt% or less are more preferable. Further, when higher durability is required, the content is more preferably 2% by weight or more and 8% by weight or less.

  Here, when the group Ib metal content is less than 85% by weight, the specific resistance of the internal electrode 12 increases, and the internal electrode 12 may generate heat when the stacked piezoelectric element is continuously driven. In order to suppress migration of the group Ib metal in the internal metal 12 to the piezoelectric body 11, the group Ib metal is preferably 85 wt% or more and 99.999 wt% or less. Moreover, 90 weight% or more and 99.9 weight% or less are preferable at the point of improving the durability of a laminated piezoelectric element. Moreover, when higher durability is required, 90.5 weight% or more and 99.5 weight% or less are more preferable. Moreover, when higher durability is calculated | required, 92 to 98 weight% is further more preferable.

  These M1 and M2 indicating the weight% of the metal component in the internal electrode 12 can be specified by an analysis method such as an EPMA (Electron Probe Micro Analysis) method.

  The metal component in the internal electrode 12 of the present invention is such that the Group VIII metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the Group Ib metal is Cu, Ag, or Au. Of these, at least one is preferable. This is because the metal composition has excellent mass productivity in recent alloy powder synthesis techniques.

  More preferably, the metal component in the internal electrode 12 of the present invention is such that the Group VIII metal is at least one of Pt and Pd, and the Group Ib metal is at least one of Ag and Au. . As a result, an electrode having excellent heat resistance can be formed, and the specific resistance of the internal electrode 12 can be reduced, so that heat generation of the internal electrode 12 portion can be suppressed even when continuously driven.

  Moreover, as for the metal component in the internal electrode 12 of this invention, it is more preferable that Ib group metal is Cu.

  Thus, in such a multilayer piezoelectric element, an electrode having excellent heat conduction characteristics can be formed, and the specific resistance of the internal electrode 12 can be reduced. Therefore, even when continuously driven, the heat generation of the internal electrode 12 portion is suppressed. be able to. Furthermore, since the amount of displacement of the piezoelectric actuator can be stabilized by suppressing an increase in element temperature, a highly reliable piezoelectric actuator having excellent durability can be provided.

  In the multilayer piezoelectric element of the present invention, the element resistance when the internal electrode 12 formation is made of 100% silver is ρAg, and the element resistance when the internal electrode 12 formation is 100% palladium is ρPd. The element resistance ρ is ρAg <ρ <ρPd.

  In other words, the composition of 70% by weight of silver and 30% by weight of palladium conventionally used for the internal electrode 12 of the multilayer piezoelectric element has a high resistance characteristic 1.5 times that of palladium, but the element resistance within the above range. In order to obtain ρ, the silver content is 80% by weight or more and palladium is 20% by weight or less. However, as the sintered density of the internal electrode 12 decreases, the resistance increases accordingly, and therefore it is preferable to further increase the composition ratio of silver or use an electrode material having a lower resistance. Furthermore, by forming a structure in which the electrode itself is sintered and large particles are combined, it is possible to obtain a dense internal electrode 12 having a low electrode resistance and an electric conduction path.

  In the multilayer piezoelectric element of the present invention, the conductivity of the internal electrode 12 when the internal electrode 12 formation is made of 100% silver is σAg, and the internal electrode 12 conductivity when the internal electrode 12 formation is 100% palladium. When the rate is σPd, σPd <σ <σAg.

  This is to increase the electrical conductivity of the internal electrode 12 in order to reduce the element resistance. That is, in an alloy of silver and palladium, in order to make the resistance lower than the specific resistance of palladium, it is 80% by weight or more and 20% by weight or less of palladium, but if the sintered density of the internal electrode 12 is lowered, Accordingly, since the resistance becomes high, it is preferable to further increase the composition ratio of silver or use an electrode material having a lower resistance. Furthermore, by forming a structure in which the electrode itself is sintered and large particles are combined, it is possible to obtain a dense internal electrode 12 having a low electrode resistance and an electric conduction path.

  Furthermore, in the multilayer piezoelectric element of the present invention, the maximum diameter of the crystal particles made of the metal composition component constituting the internal electrode 12 is 1 μm or more, and 80 vol% or more of the metal composition is present. It is characterized by that.

  This is because the electrode itself is sintered to have a structure in which large particles are combined, so that a dense internal electrode 12 having a low electrode resistance and an electric conduction path can be obtained. Preferably, the element resistance is further reduced by the presence of 90% by volume or more of crystal grains having a maximum diameter of 1 μm or more, which are composed of the metal composition component constituting the internal electrode 12. More preferably, the element resistance is further reduced by the presence of 95% by volume or more of crystal grains having a maximum diameter of 1 μm or more, which are composed of the metal composition component constituting the internal electrode 12.

  In addition, about the ratio of what the said maximum diameter is 1 micrometer or more, the location where the maximum diameter of a crystal particle becomes 1 micrometer or more is specified by analysis methods, such as SEM, for the metal composition in the internal electrode 12, and it makes volume%. It can be converted.

  Moreover, it is preferable to add an inorganic composition to the internal electrode 12 of the present invention together with the metal composition. Thereby, the internal electrode 12 and the piezoelectric body 11 can be firmly coupled.

Moreover, since the internal electrode 12 and the piezoelectric body 11 can be firmly coupled and the piezoelectric actuator displacement can be stabilized even when continuously driven, the inorganic composition is made of PbZrO ₃ —PbTiO _{3 3.} More preferably, the main component is a perovskite oxide.

Moreover, it is preferable that the piezoelectric body 11 of the present invention contains a perovskite oxide as a main component. For example, when formed of a perovskite-type piezoelectric ceramic material typified by barium titanate (BaTiO ₃ ), the amount of displacement can be increased because the piezoelectric strain constant d ₃₃ indicating the piezoelectric characteristics is high. Furthermore, the piezoelectric body 11 and the internal electrode 12 can be fired simultaneously while functioning as an excellent piezoelectric element.

Moreover, it is preferable that the piezoelectric body 11 of the present invention has a perovskite type oxide composed of PbZrO ₃ —PbTiO ₃ as a main component. In such a laminated piezoelectric element can further because of high piezoelectric strain constant d _33, a large amount of displacement.

  Further, the multilayer piezoelectric element of the present invention preferably has a firing temperature of 900 ° C. or higher and 1000 ° C. or lower. Thereby, the piezoelectric body 11 and the electrode can be firmly coupled. The reason for limiting the temperature to 900 ° C. or more and 1000 ° C. or less is that the dense piezoelectric body 11 cannot be produced at a temperature lower than 900 ° C. If the temperature exceeds 1000 ° C., the shrinkage between the shrinkage of the electrode and the shrinkage of the piezoelectric body 11 during firing This is because the stress due to the phenomenon increases and cracks occur during continuous driving.

  Further, the compositional deviation in the internal electrode 12 is preferably 5% or less before and after firing. This is because when the compositional deviation in the internal electrode 12 exceeds 5% before and after firing, the metal material in the internal electrode 12 is more migrated to the piezoelectric body 11, and the expansion and contraction due to the driving of the multilayer piezoelectric element is prevented. The internal electrode 12 may not be able to follow.

Here, the deviation of the composition in the internal electrode 12 indicates the rate of change in which the composition of the internal electrode 12 changes as the elements constituting the internal electrode 12 evaporate or diffuse into the piezoelectric body 11 by firing.

  In addition, the internal electrodes 12 whose end portions are exposed on the side surfaces of the multilayer piezoelectric element of the present invention and the internal electrodes 12 whose end portions are not exposed are alternately configured, and the internal electrodes 12 whose end portions are not exposed and A groove is formed in the piezoelectric portion between the external electrodes 15, and an insulator having a Young's modulus lower than that of the piezoelectric body 12 is preferably formed in the groove. As a result, in such a multilayer piezoelectric element, stress generated by displacement during driving can be relieved, so that heat generation of the internal electrode 12 can be suppressed even when continuously driven.

  In addition, the multilayer piezoelectric element 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.

The multilayer piezoelectric element of the present invention is manufactured as follows. First, the columnar laminate 13 is produced. A columnar laminated body 13 formed by alternately laminating a plurality of piezoelectric bodies 11 and a plurality of internal electrodes 12 includes a calcined powder of piezoelectric ceramics such as perovskite oxide made of PbZrO ₃ —PbTiO ₃ , and acrylic A slurry made by mixing a binder made of an organic polymer such as butyral and a plasticizer such as DOP (diethyl phthalate) or DBP (dibutyl phthalate) is prepared, and the slurry is prepared by a well-known doctor blade method or calendar. A ceramic green sheet to be the piezoelectric body 11 is produced by a tape molding method such as a roll method.

  Next, for example, a conductive paste is prepared by adding and mixing a binder, a plasticizer, and the like to a metal powder constituting an internal electrode such as silver-palladium, and this is applied to the upper surface of each green sheet by screen printing or the like. Print to a thickness of 40 μm.

  Then, a plurality of green sheets having conductive paste printed on the upper surface are laminated, the binder is debindered at a predetermined temperature, and then fired at 900 to 1200 ° C., whereby the columnar laminate 13 is manufactured. . Preferably, it is fired at 900 to 1000 ° C. as described above.

  The columnar laminate 13 is not limited to the one produced by the above-described manufacturing method, and any method can be used as long as the columnar laminate 13 can be produced by alternately laminating a plurality of piezoelectric bodies and a plurality of internal electrodes. It may be formed by any manufacturing method.

  Thereafter, the internal electrodes whose end portions are exposed on the side surfaces of the multilayer piezoelectric element and the internal electrodes whose end portions are not exposed are alternately configured, and the piezoelectric body portion between the internal electrodes and the external electrodes whose end portions are not exposed. When an insulating material having a lower Young's modulus than that of the piezoelectric material, such as a resin or rubber, is formed in the groove, one layer is formed on the side surface of the columnar laminate 13 by an internal dicing device or the like. Grooves are formed in

  The external electrode 15 is preferably made of silver having a low Young's modulus or an alloy containing silver as a main component because the conductive material constituting the external electrode 15 sufficiently absorbs stress generated by expansion and contraction of the actuator.

A binder is added to the glass powder to produce a silver glass conductive paste, which is formed into a sheet and dried (the solvent is scattered), and the raw density of the sheet is controlled to 6 to 9 g / cm ^3. The sheet is transferred to the external electrode forming surface of the columnar laminate 13, and is at a temperature higher than the softening point of the glass, at a temperature not higher than the melting point of silver (965 ° C.), and not higher than 4/5 of the firing temperature (° C.). By baking at a temperature, the binder component in the sheet prepared using the silver glass conductive paste is scattered and lost, and the external electrode 15 made of a porous conductor having a three-dimensional network structure can be formed.

  The baking temperature of the silver glass conductive paste effectively forms a neck portion, diffuses and joins silver in the silver glass conductive paste and the internal electrode 12, and effectively creates voids in the external electrode 15. The temperature is preferably 550 to 700 ° C. from the viewpoint that the external electrode 15 and the side surface of the columnar laminate 13 are partially joined. 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 too much, so that a porous conductor having an effective three-dimensional network structure cannot be formed, and the external electrode 15 May become too dense, and as a result, the Young's modulus of the external electrode 15 may become too high to absorb the stress during driving sufficiently and the external electrode 15 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 internal electrode 12 and the external electrode 15, the neck portion is not formed, and the internal electrode 12 and the external electrode are not driven. There is a possibility of causing a spark between the electrodes 15.

  Note that the thickness of the silver glass conductive paste sheet is preferably thinner than the thickness of the piezoelectric body 11. More preferably, it is 50 μm or less from the viewpoint of following the expansion and contraction of the actuator.

  Next, the columnar laminate 13 on which the external electrode 15 is formed is immersed in a silicone rubber solution, and the silicone rubber solution is vacuum degassed to fill the groove of the columnar laminate 13 with silicone rubber. The columnar laminate 13 is pulled up from the solution, and the side surface of the columnar laminate 13 is coated with silicone rubber. Thereafter, the silicone rubber filled in the groove and coated on the side surface of the columnar laminate 13 is cured.

  Thereafter, a lead wire is connected to the external electrode 15 to complete the multilayer piezoelectric element of the present invention.

  Then, a direct current voltage of 0.1 to 3 kV / mm is applied to the pair of external electrodes 15 via the lead wires, and the columnar laminated body 13 is polarized, thereby completing a laminated piezoelectric actuator as a product. If the wire is connected to an external voltage supply unit and a voltage is applied to the internal electrode 12 via the lead wire and the external electrode 15, each piezoelectric body 11 is greatly displaced by the reverse piezoelectric effect, thereby causing, for example, fuel to the engine. Functions as a fuel injection valve for automobiles.

  In the multilayer piezoelectric element configured as described above, the metal composition in the internal electrode 12 is mainly composed of a Group VIII metal and a Group Ib metal, and the content of the Group VIII metal in the electrode is M1 wt%, Ib When the content of the group metal is M2% by weight, 0 <M1 ≦ 15, 85 ≦ M2 <100, and M1 + M2 = 100 are satisfied. Therefore, even when the actuator is driven continuously under a high electric field, thermal runaway occurs. This can be prevented and a highly reliable actuator can be provided.

  In the multilayer piezoelectric element configured as described above, the element resistance when the metal composition component in the internal electrode 12 is made of silver is ρAg, and the element resistance when the metal composition component is made of palladium is ρPd. In this case, since the element resistance ρ becomes ρAg <ρ <ρPd, even when the actuator is continuously driven under a high electric field, the displacement does not change effectively, so that the device does not malfunction. In addition, a highly reliable piezoelectric actuator having excellent durability can be provided.

  In addition, the multilayer piezoelectric element configured as described above has the conductivity of the internal electrode 12 when the metal composition component in the internal electrode 12 is made of silver as σAg, and the internal structure when the metal composition component is made of palladium. When the electrode 12 conductivity is σPd, the internal electrode 12 conductivity σ is σPd <σ <σAg. Therefore, even when the actuator is continuously driven under a high electric field, the displacement does not change effectively. Therefore, it is possible to provide a highly reliable piezoelectric actuator having excellent durability without causing malfunction of the apparatus.

  Further, in the laminated piezoelectric element configured as described above, since there are 80% by volume or more of the crystal particles made of the metal composition component constituting the internal electrode 12 having a maximum diameter of 1 μm or more, the actuator Even when continuously driven under a high electric field, the displacement amount does not change effectively, so that a highly reliable piezoelectric actuator excellent in durability can be provided without malfunctioning the apparatus.

  Furthermore, in the present invention, a conductive auxiliary member 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 15 may be formed. In this case, even when a large current is input to the actuator by providing a conductive auxiliary member on the outer surface of the external electrode 15 and the actuator is driven at a high speed, a large current can flow through the conductive auxiliary member. For the reason that the current flowing through 15 can be reduced, the external electrode 15 can be prevented 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.

  Furthermore, the conductive adhesive constituting the conductive auxiliary member 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 high heat resistance, a conductive auxiliary member having a low resistance value and maintaining a high adhesive strength can be formed even when used at high temperatures. . More preferably, the conductive particles are non-spherical particles such as flakes or needles. This is because by making the shape of the conductive particles non-spherical particles such as flakes and needles, the entanglement between the conductive particles can be strengthened, and the shear strength of the conductive adhesive can be further increased. This is because it can be increased.

  The multilayer piezoelectric element 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 15 in the side surface which the columnar laminated body 13 opposes was demonstrated in the said example, in this invention, you may form a pair of external electrode in the side surface provided adjacently, for example.

  FIG. 3 shows an injection device according to the present invention. In the figure, reference numeral 31 denotes a storage container. 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.

  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. And in the storage container 31, the piezoelectric actuator 43 which consists of an above-described lamination type piezoelectric element 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.

  In addition, the present invention is not limited to the above-described embodiments. For example, a drive mounted on a fuel injection device for an automobile engine, a liquid injection device such as an ink jet, a precision positioning device such as an optical device, a vibration prevention device, or the like. Elements and sensor elements mounted on combustion pressure sensors, knock sensors, acceleration sensors, load sensors, ultrasonic sensors, pressure sensitive sensors, yaw rate sensors, etc., and mounted on piezoelectric gyros, piezoelectric switches, piezoelectric transformers, piezoelectric breakers, etc. Needless to say, any circuit element other than the circuit element can be used as long as the element uses piezoelectric characteristics.

  The multilayer piezoelectric element of FIG. 1 was configured as follows. Using laminated piezoelectric elements having different internal electrode material compositions, durability characteristics of the laminated piezoelectric elements having various displacement characteristics were examined.

First, a columnar laminate was produced. The piezoelectric body was formed of 150 μm thick lead zirconate titanate (PbZrO ₃ —PbTiO ₃ ), the internal electrodes were formed with a thickness of 3 μm, and the number of stacked layers of the piezoelectric body and the internal electrodes was 300 layers. The firing temperature was 1000 ° C.

  Thereafter, a groove having a depth of 50 μm and a width of 50 μm was formed at every other end of the internal electrode on the side surface of the columnar 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 weight 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. The raw density of this sheet was measured by the Archimedes method and found to be 6.5 g / cm ³ .

  Next, the silver glass paste sheet was transferred to the external electrode surface of the columnar laminate, and baked at 650 ° C. for 30 minutes to form an external electrode made of a porous conductor having a three-dimensional network structure. The porosity of the external electrode at this time was 40% when a cross-sectional photograph of the external electrode was measured using an image analyzer.

  Thereafter, a lead wire is connected to the external electrode, a 3 kV / mm DC electric field is applied to the positive electrode and the negative external electrode via the lead wire for 15 minutes to perform polarization treatment, and the laminated piezoelectric element as shown in FIG. Was made.

  As a result of applying a DC voltage of 170 V to the obtained multilayer piezoelectric element, a displacement of 45 μm was obtained in the stacking direction. 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.

By changing the internal electrode metal composition and measuring the displacement amount of the laminated piezoelectric element when the laminated piezoelectric element reaches 1 × 10 ⁹ times of driving, the initial stage of the laminated piezoelectric element before starting the continuous driving is measured. Compared with the displacement amount of the state, the change rate of the displacement amount and the degree of deterioration of the multilayer piezoelectric element were calculated. The results are as shown in Table 1.

  From the table, when the internal electrode is made of 100% silver (No. 1), the laminated piezoelectric element is damaged by silver migration and cannot be continuously driven, but the metal composition in the internal electrode is a group VIII. When the content of the metal (Pd, Pt) is M1 (wt%) and the content of the group Ib metal (Ag, Cu) is M2 (wt%), 0 <M1 ≦ 15, 85 ≦ M2 <100, M1 + M2 By using a metal composition (Nos. 2 to 15) satisfying = 100 as a main component, it was possible to provide a highly reliable piezoelectric actuator having excellent durability without causing malfunction of the apparatus. In particular, in terms of improving the durability of the multilayer piezoelectric element, M1 is preferably 0.1 wt% or more and 10 or less (Nos. 4 to 13), and is 0. 5 or more and 9.5 or less (No. 5-12) are more preferable. In addition, when higher durability was required, a more preferable result was obtained in the range of 2% to 8 (No. 7 to 10). Similarly, in terms of improving the durability of the multilayer piezoelectric element, M2 is preferably 90 or more and 99.9 or less, and when higher durability is required, 90.5 or more and 99.5 or less. Is more preferable. In the case where higher durability is required, a more preferable result is 92 to 98.

Next, the initial state of the multilayer piezoelectric element before starting continuous driving by measuring the element resistance and the displacement amount of the multilayer piezoelectric element when the multilayer piezoelectric element reaches 1 × 10 ⁹ times of driving. The change rate of the displacement amount was calculated in comparison with the displacement amount of Table 2 and listed in Table 2.

  According to the table, by setting the specific resistance ρ of the internal electrode to ρAg <ρ <ρPd, even when continuously driven, the heat generation of the internal electrode portion can be suppressed and the displacement amount of the piezoelectric actuator can be stabilized. Therefore, a highly reliable piezoelectric actuator excellent in durability could be provided.

Next, the multilayer piezoelectric element before the continuous driving is started by measuring the internal electrode conductivity and the displacement amount of the multilayer piezoelectric element when the multilayer piezoelectric element reaches the driving frequency of 1 × 10 ⁹ times. The change rate of the displacement amount was calculated in comparison with the displacement amount in the initial state, and is shown in Table 3.

  According to the table, by setting the internal electrode conductivity σ to be σPd <σ <σAg, the heat generation of the internal electrode portion can be suppressed even when continuously driven, and the displacement amount of the piezoelectric actuator can be stabilized. It was possible to provide a highly reliable piezoelectric actuator with excellent durability.

Next, the displacement amount of the stacked piezoelectric element when the crystal particles comprising the metal composition component constituting the internal electrode and the stacked piezoelectric element reach the number of times of driving 1 × 10 ⁹ times is measured continuously. The change rate of the displacement amount was calculated and compared with the displacement amount in the initial state of the multilayer piezoelectric element before the drive was started, and is shown in Table 4.

  According to the table, the presence of 80% by volume or more of the crystal particles composed of the metal composition component constituting the internal electrode having a maximum diameter of 1 μm or more suppresses heat generation in the internal electrode even when continuously driven. Since the displacement amount of the piezoelectric actuator can be stabilized, a highly reliable piezoelectric actuator having excellent durability can be provided.

  It should be noted that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention.

1A and 1B show a laminated piezoelectric element of the present invention, in which FIG. 1A is a perspective view, and FIG. 1B is a perspective developed view showing a laminated state of a piezoelectric layer and an internal electrode layer. 1A and 1B show a multilayer capacitor, in which FIG. 1A is a perspective view, and FIG.

It is a perspective view.
It is explanatory drawing which shows the injection apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Piezoelectric body 13 ... Columnar laminated body 12 ... Internal electrode 21 ... Dielectric 22 ... Internal electrode 23 ... External electrode 31 ... Storage container 33 ... Injection hole 35 ... Valve 43 ... Piezoelectric actuator

Claims (15)

It has a laminate formed by alternately laminating at least one piezoelectric body and a plurality of internal electrodes, and has a pair of external electrodes in which the internal electrodes are alternately connected to every other side surface of the laminate, In the multilayer piezoelectric element driven by applying an electric field to the external electrode, the metal composition in the internal electrode is mainly composed of a group VIII metal and a group Ib metal in the periodic table, and the content of the group VIII metal is M1. A multilayer piezoelectric element satisfying 0 <M1 ≦ 15, 85 ≦ M2 <100, and M1 + M2 = 100 when the content of the group Ib metal is (% by weight) and M2 (% by weight). The group VIII metal is at least one of Ni, Pt, Pd, Rh, Ir, Ru, and Os, and the group Ib metal is at least one of Cu, Ag, and Au. Item 2. A laminated piezoelectric element according to Item 1. 3. The stacked type according to claim 1, wherein the Group VIII metal is at least one of Pt and Pd, and the Group Ib metal is at least one of Ag and Au. 4. Piezoelectric element. The multilayer piezoelectric element according to claim 1, wherein the group Ib metal is Cu. It has a laminate formed by alternately laminating at least one piezoelectric body and a plurality of internal electrodes, and has a pair of external electrodes in which the internal electrodes are alternately connected to every other side surface of the laminate, In the multilayer piezoelectric element driven by applying an electric field to the external electrode, the element resistance when the metal composition component in the internal electrode is made of silver is ρAg, and the element resistance when the metal composition component is made of palladium. A multilayer piezoelectric element characterized in that, when ρPd, the element resistance ρ satisfies ρAg <ρ <ρPd. It has a laminate formed by alternately laminating at least one piezoelectric body and a plurality of internal electrodes, and has a pair of external electrodes in which the internal electrodes are alternately connected to every other side surface of the laminate, In the multilayer piezoelectric element driven by applying an electric field to the external electrode, the electrical conductivity of the internal electrode when the metal composition component in the internal electrode is made of silver is σAg, and the metal composition component is made of palladium. A multilayer piezoelectric element, wherein the internal electrode conductivity σ satisfies σPd <σ <σAg when the internal electrode conductivity is σPd. It has a laminate formed by alternately laminating at least one piezoelectric body and a plurality of internal electrodes, and has a pair of external electrodes in which the internal electrodes are alternately connected to every other side surface of the laminate, In the laminated piezoelectric element that is driven by applying an electric field to the external electrode, the crystal particles comprising the metal composition component constituting the internal electrode have a maximum diameter of 1 μm or more, and 80% by volume or more of the metal composition exists. And a laminated piezoelectric element. The multilayer piezoelectric element according to claim 1, wherein an inorganic composition is added to the internal electrode together with the metal composition. The multilayer piezoelectric element according to claim 8, wherein the inorganic composition contains a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ as a main component. The multilayer piezoelectric element according to claim 1, wherein the piezoelectric body contains a perovskite oxide as a main component. The multilayer piezoelectric element according to claim 10, wherein the piezoelectric body is mainly composed of a perovskite oxide composed of PbZrO ₃ —PbTiO ₃ . The multilayer piezoelectric element according to any one of claims 1 to 11, wherein a firing temperature of the multilayer body is 900 ° C or higher and 1000 ° C or lower. The multilayer piezoelectric element according to any one of claims 1 to 12, wherein the compositional deviation in the internal electrode is 5% or less before and after firing. An internal electrode having an external electrode on a side surface of the multilayer piezoelectric element, and an internal electrode with an end portion exposed on the side surface and an internal electrode with an end portion not exposed are alternately formed, and the internal portion in which the end portion is not exposed 14. A groove is formed in a piezoelectric portion between the electrode and the external electrode, and an insulator having a Young's modulus lower than that of the piezoelectric body is filled in the groove. The laminated piezoelectric element according to 1. A storage container having an injection port, the stacked piezoelectric element according to any one of claims 1 to 14 stored in the storage container, and a valve for ejecting liquid from the injection hole by driving the stacked piezoelectric element An injection device characterized by comprising

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