WO2009096381A1 - Élément piézo-électrique stratifié, et injecteur équipé d'un élément piézo-électrique stratifié et système d'injection de carburant - Google Patents

Élément piézo-électrique stratifié, et injecteur équipé d'un élément piézo-électrique stratifié et système d'injection de carburant Download PDF

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Publication number
WO2009096381A1
WO2009096381A1 PCT/JP2009/051253 JP2009051253W WO2009096381A1 WO 2009096381 A1 WO2009096381 A1 WO 2009096381A1 JP 2009051253 W JP2009051253 W JP 2009051253W WO 2009096381 A1 WO2009096381 A1 WO 2009096381A1
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Prior art keywords
internal electrode
piezoelectric element
internal
facing portion
electrodes
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PCT/JP2009/051253
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English (en)
Japanese (ja)
Inventor
Takeshi Okamura
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Kyocera Corporation
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Application filed by Kyocera Corporation filed Critical Kyocera Corporation
Priority to JP2009551520A priority Critical patent/JP5154580B2/ja
Publication of WO2009096381A1 publication Critical patent/WO2009096381A1/fr

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • H10N30/871—Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • H10N30/508—Piezoelectric or electrostrictive devices having a stacked or multilayer structure adapted for alleviating internal stress, e.g. cracking control layers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M51/00—Fuel-injection apparatus characterised by being operated electrically
    • F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
    • F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means

Definitions

  • the present invention relates to a laminated piezoelectric element used for, for example, a driving element (piezoelectric actuator), a sensor element, and a circuit element.
  • the driving element include 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, and a vibration prevention device.
  • the sensor element include a combustion pressure sensor, a knock sensor, an acceleration sensor, a load sensor, an ultrasonic sensor, a pressure sensor, and a yaw rate sensor.
  • Examples of the circuit element include a piezoelectric gyro, a piezoelectric switch, a piezoelectric transformer, and a piezoelectric breaker.
  • multilayer piezoelectric elements have been required to ensure a large amount of displacement under a large pressure at the same time as miniaturization proceeds. For this reason, it is required that a higher voltage is applied and that the device can be used under severe conditions in which continuous driving is performed for a long time.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a laminated piezoelectric element in which a decrease in displacement due to long-time driving is improved.
  • the multilayer piezoelectric element according to the present invention includes a multilayer body having a plurality of piezoelectric bodies and a plurality of internal electrodes, the piezoelectric bodies and the internal electrodes being alternately stacked, and a first side surface of the multilayer body.
  • the plurality of internal electrodes on the first and second side surfaces are respectively connected to the first external electrodes such that the plurality of internal electrodes are alternately connected to one of the first and second external electrodes.
  • the internal electrodes connected to the second external electrodes and the internal electrodes that are insulated and separated by being formed away from the first side surface or the second side surface are alternately arranged.
  • the stacked body includes a facing portion where the adjacent internal electrodes face each other in the stacking direction, and a non-facing portion provided along the first and second side surfaces, facing each other of the internal electrodes.
  • a laminated piezoelectric element divided into At least one of the plurality of internal electrodes has a plurality of internal electrode non-formation sites provided in the internal electrode along a boundary between the facing portion and the non-facing portion.
  • At least one of the plurality of internal electrodes includes a plurality of internal electrode non-formation sites surrounded by the internal electrode, and the opposing portion and the non-opposing portion. It has along the boundary.
  • FIG. 1 is a perspective view showing a multilayer piezoelectric element according to a first embodiment of the present invention.
  • FIG. 1B is a partial exploded perspective view of the multilayer piezoelectric element of FIG. 1A. It is sectional drawing orthogonal to the lamination direction of the lamination type piezoelectric element shown to FIG. 1A and 1B, and is sectional drawing which shows the cross section of the internal electrode which has an internal electrode non-formation site
  • FIG. 6A which has an internal electrode non-formation site
  • FIG. 9 It is a perspective view which shows the lamination type piezoelectric element of the 6th Embodiment concerning this invention. It is sectional drawing orthogonal to the lamination direction of the lamination type piezoelectric element shown in FIG. 9, and is sectional drawing which shows the cross section of the internal electrode which has an internal electrode non-formation site
  • FIG. 1A is a perspective view showing a multilayer piezoelectric element according to the first embodiment of the present invention.
  • FIG. 1B is an exploded perspective view of a part of the multilayer piezoelectric element according to the embodiment shown in FIG. 1A.
  • 2A, 2B, and 2C are cross-sectional views each including internal electrodes adjacent to each other in the direction perpendicular to the stacking direction in the embodiment shown in FIG.
  • the multilayer piezoelectric element 1 (hereinafter also simply referred to as element 1) of the present embodiment has a plurality of piezoelectric bodies 3 and a plurality of internal electrodes 5, and the piezoelectric body 3 And a laminated body 7 in which the internal electrodes 5 are alternately laminated.
  • the multilayer piezoelectric element 1 includes two external electrodes 11.
  • one (cathode side) external electrode 11 is formed on the first side surface, which is one side surface of the multilayer body 7, and the other (anode side) external electrode.
  • the electrode 11 is formed on the second side surface facing the first side surface (FIG. 1A).
  • the internal electrodes 5 and 9 serving as the negative electrode are formed so as to reach the first side surface, are connected to the external electrode 11 on the first side surface, are formed apart from the second side surface, and are external on the anode side. It is electrically separated from the electrode 11.
  • the internal electrodes 5 and 9 serving as positive electrodes are formed so as to reach the second side surface, are connected to the external electrode 11 on the second side surface, are formed away from the first side surface, and are external to the cathode side. It is electrically separated from the electrode 11.
  • the internal electrodes 5, 9 serving as the negative electrode and the internal electrodes 5, 9 serving as the positive electrode are alternately arranged, and each piezoelectric body 3 is sandwiched between the internal electrodes 5, 9 of the negative electrode and the positive electrode.
  • a structure is realized.
  • the portions where the electrodes are not formed on the piezoelectric body 3 formed by forming the internal electrodes 5 and 9 away from the end portions (first side surface or second side surface) are insulated and separated. This is referred to as part 70.
  • the active region where the piezoelectric body 3 is sandwiched between the positive and negative internal electrodes 5 and 9 and voltage is applied to the sandwiched portion is the first side surface and the second side region.
  • An inactive region that is formed away from the side surface by the width of the insulating separation portion 70 and that has the same polarity of the internal electrodes facing each other with the insulating separation portion 70 interposed therebetween is an inactive region where no voltage is applied to the piezoelectric body 3. It is formed along the side. In this manner, the stacked body 7 is divided into an active region and a non-active region other than the pair of positive and negative internal electrodes 5 adjacent to each other in the stacking direction.
  • an active region in which the piezoelectric body 3 is sandwiched between the positive and negative internal electrodes 5 and 9 facing each other is referred to as a facing portion 7a, and the inactive where the positive and negative internal electrodes 5 and 9 are not facing each other.
  • the region is referred to as a non-facing portion 7b.
  • At least one internal electrode 9 among the plurality of internal electrodes 5 has a plurality of openings (referred to as internal electrode non-formation sites 7 c) each surrounded by the internal electrode 9. It has along the boundary 7d of the opposing part 7a and the non-opposing part 7b, It is characterized by the above-mentioned.
  • the internal electrode 9 has a plurality of internal electrode non-formed portions 7c (hereinafter also referred to as non-formed portions 7c) and is positioned so as to straddle the boundary 7d between the facing portion 7a and the non-facing portion 7b.
  • the portion will be referred to as the first portion 9a and will be described as the other second portion 9b.
  • part 9a is an area
  • part 9b is defined as follows. When a voltage is applied to the external electrode 11, the electric field transmitted to the internal electrode 9 is once disturbed by the internal electrode non-formation site 7c, but the electric field intensity distribution is once disturbed. A phenomenon occurs in which the intensity is aligned in a single line.
  • the boundary between the first part 9a and the second part 9b is defined as the position of the line where the electric field strengths are aligned.
  • the insulating separation portion 70 is generally separated from the boundary 7d between the facing portion 7a and the non-facing portion 7b. It is a position away from the external electrode 11 by a distance of.
  • the ratio of the internal electrode 5 in the first part 9a is smaller than the ratio of the internal electrode 5 in the second part 9b. It is preferable.
  • the multilayer piezoelectric element 1 continuously undergoes dimensional changes when driven, but the piezoelectric element 3 is driven in close contact with the internal electrode 5 so that the element 1 is large as a whole. Drive deformation. Therefore, a relatively large stress is applied to the end portion of the element 1.
  • the non-formation part 7c of the first part 9a is in the above-described form, the amount of displacement at the end portion close to the end face of the element 1 can be reduced. As a result, the stress applied to the end portion of the element 1 can be reduced, and the durability of the element 1 can be improved.
  • At least one of the plurality of internal electrodes 5 and 9 has a plurality of internal electrode non-formation sites 7c each surrounded by the internal electrode 9 as opposed to the opposing portion 7a. Since it has along the boundary 7d with the opposing part 7b, the driving force in the boundary 7d vicinity with the non-opposing part 7b can be made small among the opposing parts 7a. That is, the driving force is small as compared with the central portion of the facing portion 7a along the boundary 7d between the facing portion 7a and the non-facing portion 7b, in the facing portion 7a or across the facing portion 7a and the non-facing portion 7b. A portion is formed, and the driving force can be reduced stepwise toward the non-opposing portion 7b. As a result, stress concentration at the boundary 7d can be suppressed, and high durability can be realized.
  • the first portion 9 a is located between the portion of the internal electrode 9 that is located in the facing portion 7 a and contributes to driving the element 1 and the portion that is connected to the external electrode 11. ing.
  • the ratio of the internal electrode 5 in the first part 9a is smaller than the ratio of the internal electrode 5 in the second part 9b. Therefore, in the portion where the plurality of internal electrode non-formation sites 7c are formed, the current path when the current flows becomes narrow, so the current density when the overcurrent flows is higher than the other portions, Damage is likely to occur.
  • the first portion 9a when the first portion 9a is located at a location where current is passed from the external electrode 11 to the portion of the internal electrode 9 that contributes to driving of the device 1, a very strong voltage is applied to the device 1. A part of the first portion 9a is broken. Thereby, it is suppressed that an excessive voltage is applied to the portion of the internal electrode 9 that contributes to driving of the element 1. As a result, it is possible to suppress the piezoelectric body 3 from being displaced excessively and causing cracks.
  • the electrode portion between adjacent internal electrode non-formation sites 7c is damaged. As described above, the interval between the internal electrode non-formation sites 7c can also be set.
  • the first portion 9a is located between the portion contributing to driving of the element 1 and the portion connected to the external electrode 11, and only in the first portion 9a.
  • the non-formed part 7c stress is easily applied to the first part 9a. Therefore, since it is known in advance that the first portion 9a of the internal electrode 9 is likely to break, it is easy to predict the driving state of the element 1 over a long period of time. As a result, the reliability with respect to the displacement amount of the element 1 can be improved.
  • the plurality of internal electrode non-formed portions 7c are aligned in a direction parallel to the boundary 7d between the facing portion 9b and the non-facing portion 9a. It is more preferable that the plurality of aligned internal electrode non-formed sites 7c are arranged at equal intervals.
  • the plurality of internal electrode non-formation sites 7c are arranged at equal intervals in one direction, and the first site 9a has a lattice shape with the internal electrode non-formation sites 7c as lattices. That's it.
  • the lattice shape of the lattice shape may be arranged in a row or in a plurality of rows.
  • FIG. 3A to 3C are cross-sectional views orthogonal to the stacking direction of the multilayer piezoelectric element 1 according to the modification of the first embodiment, and illustrate cross sections including the internal electrodes 5 and 9.
  • FIG. 3A shows the internal electrode 9 shown in FIG. 3B and the internal electrode 9 adjacent to one end face side of the laminate 7.
  • FIG. 3C shows the internal electrode 9 shown in FIG. 3B and the internal electrode 5 adjacent to the other end face side of the stacked body 7.
  • the end surface of the laminated body 7 refers to the outer surface orthogonal to the lamination direction of the internal electrodes 5 and 9 and the piezoelectric body 3, and refers to the upper surface and the lower surface in FIG. 1A.
  • the laminated piezoelectric element 1 of this modification is different from the element 1 of the first embodiment in which the internal electrode non-forming part 7c is circular, except that the internal electrode non-forming part 7c is rectangular.
  • the configuration is the same as the element 1 of the first embodiment.
  • the lattice shape in the present invention includes a circular shape as shown in FIG. 3, and the lattice shape as shown in FIG. 2 is not limited to a square shape.
  • the lattice in the first portion 9a of the internal electrode 9 is substantially square. It is also effective that the corners have a curved shape.
  • the internal electrode non-forming portion 7c is a boundary between the facing portion 7a and the non-facing portion 7b when the internal electrode 9 is viewed in plan view. 7d is preferred. That is, it is preferable that the internal electrode non-formation site 7c is formed across the facing portion 7a and the non-facing portion 7b. In this case, it is possible to reduce the driving force at the boundary 7d between the facing portion 7a and the non-facing portion 7b where the stress is most likely to concentrate among the facing portions 7a, so that the durability of the element 1 can be further increased. it can.
  • the configuration in which the plurality of internal electrodes 9 have the first portion 9a is shown.
  • at least one internal polarization 9 is the first What is necessary is just to have the site
  • At least one of the internal electrodes 5, 9 connected to the anode-side external electrode 11a and the internal electrodes 5, 9 connected to the cathode-side external electrode 11b has a first portion 9a. More preferably. Thereby, since the bias of the stress distribution can be reduced, the driving direction of the element 1 can be stabilized.
  • the pair of internal electrodes 5 and 9 adjacent in the stacking direction each have the first portion 9a. This is because the amount of displacement of the piezoelectric body 3 sandwiched between the internal electrodes 5 and 9 can be further reduced, and the effect of absorbing stress in the piezoelectric body 3 can be further enhanced.
  • all the internal electrodes 5, 9 have the first portion 9a.
  • the stress can be dispersed in a wider range, and the bias of the stress distribution can be further reduced.
  • FIG. 4A to 4C are cross-sectional views orthogonal to the stacking direction in the multilayer piezoelectric element 1 according to the second embodiment of the present invention, and illustrate cross sections including the internal electrodes 5.
  • FIG. 4A shows the internal electrode 9 shown in FIG. 4B and the internal electrode 9 adjacent to one end face side of the laminate 7.
  • FIG. 4C shows the internal electrode 9 shown in FIG. 4B and the internal electrode 5 adjacent to the other end face side of the multilayer body 7.
  • the non-formed portion 7c in the first portion 9a of the internal electrode 9 is a boundary between the facing portion 7a and the non-facing portion 7b.
  • the point which is arranged in a plurality of rows in parallel with 7d is different from the first embodiment.
  • the non-forming portion 7c in the first portion 9a is arranged in a plurality of rows in parallel with the boundary 7d between the facing portion 7a and the non-facing portion 7b, one of the plurality of rows is the facing portion 7a. It is preferably located on the boundary 7d between the non-opposing portion 7b.
  • first portion 9a Since the first portion 9a is located between the portion of the internal electrode 9 that is located at the facing portion 7a and contributes to driving the element 1 and the portion that is connected to the external electrode 11, stress is generated at the non-forming portion 7c. Can be relaxed. Thereby, it can suppress that stress concentrates on the peripheral part of the internal electrode 5.
  • FIG. 5A to 5A are cross-sectional views orthogonal to the stacking direction of the multilayer piezoelectric element 1 according to the modification of the second embodiment shown in FIG. 4, and illustrate cross sections including the internal electrodes 5 and 9. Yes.
  • FIG. 5A shows the internal electrode 9 shown in FIG. 5B and the internal electrode 9 adjacent to one end face side of the laminate 7.
  • FIG. 5C shows the internal electrode 9 shown in FIG. 5B and the internal electrode 5 adjacent to the other end face side of the multilayer body 7.
  • the non-forming portion 7c constituting the row located on the boundary 7d between the facing portion 7a and the non-facing portion 7b may be larger than the other non-forming portions 7c. Even more preferred. This is because the driving force at the boundary 7d between the opposing portion 7a and the non-opposing portion 7b where stress is most likely to concentrate can be reduced, and the durability of the element 1 can be further increased.
  • FIG. 6A to 6B are cross-sectional views orthogonal to the stacking direction in the multilayer piezoelectric element 1 according to the third embodiment of the present invention, and illustrate a cross section including the internal electrode 5.
  • FIG. 6A shows the internal electrode 9 shown in FIG. 6B and the internal electrode 9 adjacent to one end side in the stacking direction.
  • 6C shows the internal electrode 5 shown in FIG. 6B and the internal electrode 5 adjacent to the other end side in the stacking direction.
  • the anode-side and cathode-side external electrodes 11a, 11b are respectively located on opposite side surfaces of the multilayer body 7, and a boundary 7d between the facing portion 7a and the non-facing portion 7b is separated from each other.
  • at least one internal electrode 9 of the plurality of internal electrodes 5 has a first portion 9a on each boundary 7d. That is, the internal electrode 9 having the internal electrode non-forming portion 7c along the boundary 7d between the facing portion 7a and the one non-facing portion 7b further extends along the boundary 7d between the facing portion 7a and the other non-facing portion 7b.
  • the boundary 7d between the facing portion 7a and the non-facing portion 7b exists at a plurality of locations separated from each other, among the plurality of internal electrodes 5, the internal electrodes 9 adjacent to each other in the stacking direction It is preferable that the 1st site
  • the first portions 9 a are positioned to face each other, so that the drive shaft of the element 1 is less shaken and the durability is improved.
  • FIG. 7 is a perspective view showing a multilayer piezoelectric element according to the fourth embodiment of the present invention.
  • the plurality of internal electrodes 9 having the first portion 9a of the internal electrodes 5 are periodically arranged according to a certain rule in the stacking direction, This is a more preferable embodiment according to the present invention. Thereby, since the stress applied to the entire element 1 can be dispersed in the stacking direction, the element 1 having high durability can be provided.
  • FIG. 8A is a perspective view showing a multilayer piezoelectric element according to the fifth embodiment of the present invention.
  • FIG. 8B is a cross-sectional view taken along the line AA in the fifth embodiment shown in FIG. 8A and including the internal electrode 9.
  • FIG. 8C is a cross-sectional view taken along the line BB in the fifth embodiment shown in FIG. 8A and including the internal electrode 9.
  • a pair of internal electrodes 9 adjacent in the stacking direction each have a first portion 9 a, and the internal electrode 9 occupies the first portion 9 a of the internal electrode 9 close to the end face of the stacked body 7.
  • the ratio is preferably smaller than the ratio occupied by the internal electrode 9 in the first portion 9 a of the internal electrode 9 that is far from the end face of the multilayer body 7. That is, of the pair of internal electrodes 9 having the internal electrode non-formation site 7 c, the ratio of the internal electrode 9 near the end surface of the multilayer body 7 to the internal electrode non-formation site 7 c is located far from the end surface of the multilayer body 7. It is preferable that the ratio of the internal electrode 9 occupied by the internal electrode non-formation site 7c is larger.
  • the multilayer piezoelectric element 1 continuously undergoes dimensional changes when driven.
  • the element 1 is largely driven and deformed integrally. Therefore, a relatively large stress is applied to the end portion of the element 1.
  • the non-formation part 7c of the first part 9a is in the above-described form, so that the stress applied to the end part of the element 1 is reduced. Can be reduced. As a result, the durability of the element 1 can be improved.
  • the non-formation site 7c gradually increases toward the end face side of the laminate 7, and it is even more preferable that the degree of increase is regular.
  • the stress applied to the laminated piezoelectric element 1 gradually increases as it is closer to the end face of the element 1.
  • the stress generated at the boundary 7d between the facing portion 7a and the non-facing portion 7b becomes closer to the end surface of the element 1 because the non-forming portion 7c gradually increases toward the end surface side or gradually according to a certain rule. This is because the effect of relaxing the stress can be gradually increased, so that the bias of the stress distribution in the stacking direction of the element 1 can be further reduced.
  • the internal electrode 9 located on the end face side in the stacking direction among the plurality of internal electrodes 5 has the first portion 9a.
  • the internal electrode 9 located on the most end surface side in the stacking direction has the first portion 9a, so that the stress can be efficiently applied. This is because it can be relaxed. As a result, the durability of the element 1 can be further increased.
  • FIG. 9 is a perspective view showing a multilayer piezoelectric element according to the sixth embodiment of the present invention.
  • 10A to 10C are cross-sectional views orthogonal to the stacking direction in the embodiment shown in FIG. 9, each showing a cross section including the internal electrode 5.
  • FIG. 10A shows the internal electrode 9 shown in FIG. 10B and the internal electrode 9 adjacent to one end face side of the laminate 7.
  • FIG. 10C shows the internal electrode 9 shown in FIG. 10B and the internal electrode 5 adjacent to the other end face side of the multilayer body 7.
  • the multilayer piezoelectric element 1 of the sixth embodiment includes a plurality of piezoelectric bodies 3 and a plurality of internal electrodes 5, and the piezoelectric bodies 3 and the internal electrodes 5 are alternately stacked.
  • the laminated body 7 is provided.
  • the stacked body 7 is divided into a pair of positive and negative internal electrodes 5 adjacent to each other in the stacking direction, a facing portion 7a facing in the stacking direction and the other non-facing portion 7b.
  • At least one internal electrode 9 among the plurality of internal electrodes 5 has a lattice shape, and includes a first portion 9c and a second portion 9d having a finer lattice than the first portion 9c.
  • the second internal electrode non-forming part 7e having a smaller area than the internal electrode non-forming part 7c is further away from the boundary 7d than the internal electrode non-forming part 7c.
  • part 9c is located on the boundary 7d of the opposing part 7a and the non-opposing part 7b.
  • external electrodes 11 a and 11 b are located on the side surface of the multilayer body 7.
  • the plurality of internal electrodes 5 are connected to one of the anode-side and cathode-side external electrodes 11a and 11b, respectively.
  • the multilayer piezoelectric element 1 since the lattice of the first portion 9c is larger than the lattice of the second portion 9d, a voltage is applied to the first portion 9c.
  • the driving force applied to the piezoelectric body 3 is smaller than the driving force applied to the piezoelectric body 3 by applying a voltage to the second portion 9d.
  • part 9c is located on the boundary 7d of the opposing part 7a and the non-opposing part 7b, the driving force in the vicinity of the boundary 7d with the non-opposing part 7b is relatively made among the opposing parts 7a. Since it becomes small, it can suppress that the stress concerning this boundary 7d vicinity concentrates. As a result, the multilayer piezoelectric element 1 having high durability can be provided.
  • the second portion 9b does not have the non-forming portions 7c and 7e, on the boundary or the boundary between the facing portion 7a and the non-facing portion 7b
  • the stress applied near the boundary 7d between the facing part 7a and the non-facing part 7b can be reduced.
  • the internal electrode 9 having the first part 9c and the second part 9d The displacement amount of the entire adjacent piezoelectric body 3 can be reduced. As a result, the stress can be relaxed in the entire piezoelectric body 3, so that the stress applied to the end portion on the end face side of the element 1 can be reduced.
  • 11A to 11C are cross-sectional views in the direction perpendicular to the stacking direction in the stacked piezoelectric element according to the seventh embodiment of the present invention, and show cross sections each including the internal electrode 5 adjacent in the stacking direction. Yes.
  • the cross section shown in FIG. 11A is located closer to the end side of the element than the cross section shown in FIG. 11C.
  • the multilayer piezoelectric element 1 of the seventh embodiment is that the lattice in the second portion 9 d of the internal electrode 9 becomes gradually rough toward the end face side in the sixth embodiment.
  • This is a more preferable form in this respect. That is, the area of the second internal electrode non-forming portion 7e formed on the internal electrode 9 near the end face of the multilayer body 7 is larger.
  • the multilayer piezoelectric element 1 is largely driven and deformed as a unit, a greater stress is applied to the end of the element 1 closer to the end.
  • the non-formation site 7c is gradually roughened toward the end portion, the effect of dispersing the stress generated at the boundary between the facing portion 7a and the non-facing portion 7b increases as the end portion of the element 1 is closer. . Thereby, the bias of the stress distribution in the stacking direction of the element 1 can be further reduced.
  • a ceramic green sheet to be the piezoelectric body 3 is produced. Specifically, a calcined powder of piezoelectric ceramic, a binder composed of an acrylic or butyral organic polymer, and a plasticizer are mixed to prepare a slurry. And a ceramic green sheet is produced by using this slurry for tape forming methods, such as a known doctor blade method and a calender roll method.
  • the piezoelectric ceramic any material having piezoelectric characteristics may be used. For example, a perovskite oxide made of PbZrO 3 —PbTiO 3 or the like can be used.
  • the plasticizer dibutyl phthalate (DBP), dioctyl phthalate (DOP), or the like can be used.
  • a conductive paste to be the internal electrode 5 is produced.
  • a conductive paste can be prepared by adding and mixing a binder, a plasticizer, and the like with a metal powder such as silver-palladium. This conductive paste is disposed on the ceramic green sheet using a screen printing method. Further, a plurality of ceramic green sheets on which the conductive paste is screen-printed are stacked. Then, as will be described later, the laminate 7 including the piezoelectric body 3 and the internal electrode 5 can be formed by firing.
  • the internal electrode 9 having the lattice-shaped first portion can be formed, for example, by changing the pattern shape of the screen.
  • the lattice roughness can also be changed by changing the pattern shape of the screen.
  • the laminated body 7 is not limited to the one produced by the above manufacturing method, and any method can be used as long as a laminated body 7 in which a plurality of piezoelectric bodies 3 and a plurality of internal electrodes 5 are alternately laminated can be produced. It may be formed by any manufacturing method.
  • the external electrode 11 is formed so as to be electrically connected to the internal electrodes 5 and 9 and the piezoelectric body 3 whose end portions are exposed on the outer surface of the multilayer piezoelectric element 1.
  • the external electrode 11 can be obtained by adding a binder to glass powder to produce a silver glass conductive paste, printing it, and then drying and bonding or baking.
  • the laminate 7 on which the external electrode 11 is formed is immersed in a resin solution containing an exterior resin made of silicone rubber. Then, the silicone resin solution is vacuum degassed to bring the silicone resin into close contact with the concavo-convex portions on the outer peripheral side surface of the laminate 7, and then the laminate 7 is pulled up from the silicone resin solution. Thereby, a silicone resin (not shown) is coated on the side surface of the laminate 7. Then, the lead wire is connected to the external electrode 11 as a current-carrying portion with a conductive adhesive (not shown) or the like.
  • the multilayer piezoelectric element 1 of the embodiment is completed by applying a DC electric field of 0.1 to 3 kV / mm to the pair of external electrodes 11 via the lead wires to polarize the multilayer body 7.
  • a DC electric field of 0.1 to 3 kV / mm
  • each piezoelectric body 3 can be largely displaced by the inverse piezoelectric effect. it can.
  • This makes it possible to function as an automobile fuel injection valve that injects and supplies fuel to the engine, for example.
  • FIG. 12 is a schematic cross-sectional view showing an injection device according to an embodiment of the present invention.
  • the multilayer piezoelectric element 1 represented by the above embodiment is stored in a storage container 25 having an injection hole 23 at one end.
  • a needle valve 27 capable of opening and closing the injection hole 23 is disposed in the storage container 25 in the storage container 25, a needle valve 27 capable of opening and closing the injection hole 23 is disposed.
  • a fluid passage 29 is arranged in the injection hole 23 so as to be able to communicate with the movement of the needle valve 27.
  • the fluid passage 29 is connected to an external fluid supply source, and fluid is constantly supplied to the fluid passage 29 at a high pressure. Therefore, when the needle valve 27 opens the injection hole 23, the fluid supplied to the fluid passage 29 is ejected to the outside or an adjacent container, for example, a fuel chamber (not shown) of the internal combustion engine. .
  • the upper end portion of the needle valve 27 has a large inner diameter, and a cylinder 31 formed in the storage container 25 and a piston 33 that can slide are disposed. In the storage container 25, the multilayer piezoelectric element 1 described above is stored.
  • the fluid passage 29 may be opened by applying a voltage to the multilayer piezoelectric element 1 and the fluid passage 29 may be closed by stopping the application of the voltage.
  • the ejection device 21 of the present invention includes a container having the ejection holes 23 and the multilayer piezoelectric element 1 described above, and discharges the fluid filled in the container from the ejection holes 23 by driving the multilayer piezoelectric element 1.
  • You may be comprised so that it may make. That is, the multilayer piezoelectric element 1 does not necessarily have to be inside the container, and may be configured so that pressure is applied to the inside of the container by driving the multilayer piezoelectric element 1.
  • the fluid includes various liquid fluids (such as conductive paste) and gas in addition to fuel and ink.
  • the injection device 21 employing the multilayer piezoelectric element 1 of the present invention is used in an internal combustion engine, fuel can be injected into the fuel chamber of the internal combustion engine such as an engine with a longer period of time with higher accuracy than the conventional injection device 21. .
  • FIG. 13 is a schematic block diagram showing a fuel injection system according to an embodiment of the present invention.
  • the fluid ejection system 41 of the present embodiment includes a common rail 43 that stores high-pressure fluid, a plurality of the above-described injection devices 21 that inject the fluid stored in the common rail 43, and a high pressure applied to the common rail 43.
  • a pressure pump 45 that supplies fluid and an injection control unit 47 that supplies a drive signal to the injection device 21 are provided.
  • the ejection control unit 47 controls the amount and timing of fluid ejection based on external information or an external signal. For example, when an injection control unit is used for fuel injection of the engine, the amount and timing of fuel injection can be controlled while sensing the condition in the combustion chamber of the engine with a sensor or the like.
  • the pressure pump 45 plays a role of feeding fluid fuel from the fluid tank 49 to the common rail 43 at a high pressure. For example, in the case of an engine fuel injection system, the fluid is fed into the common rail 43 at about 1000 to 2000 atmospheres (about 101 MPa to about 203 MPa), preferably about 1500 to 1700 atmospheres (about 152 MPa to about 172 MPa).
  • the fuel sent from the pressure pump 45 is stored and sent to the injection device 21 as appropriate.
  • the injection device 21 injects a certain fluid from the injection hole 23 to the outside or an adjacent container. For example, in the case of an engine, fuel is injected into the combustion chamber in the form of a mist.
  • the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the present invention.
  • the present invention relates to a multilayer piezoelectric element, an injection device, and a fuel injection system, but is not limited to the above-described embodiment, and can be implemented as long as the element utilizes piezoelectric characteristics.
  • a laminated piezoelectric element was produced as follows.
  • a slurry is prepared by mixing a raw material powder mainly composed of lead zirconate titanate (PZT) powder having an average particle diameter of 0.4 ⁇ m, a binder and a plasticizer, and a ceramic green sheet having a thickness of 150 ⁇ m is formed by a doctor blade method.
  • PZT lead zirconate titanate
  • a conductive paste was prepared by adding a binder to a raw material powder containing silver-palladium alloy powder having a metal composition of 95% by mass of Ag and 5% by mass of Pd.
  • the conductive paste was printed on one side of the ceramic green sheet to a thickness of 30 ⁇ m by screen printing. And each green sheet on which the conductive paste was printed was laminated to produce a laminate. Note that the number of internal electrodes was 300 so that the number of internal electrodes was 300, and only 20 ceramic green sheets on which no conductive paste was printed were stacked at both ends in the stacking direction of the stack.
  • each internal electrode was not provided with the lattice-shaped first portion, and the cross-sectional areas of each internal electrode were all the same.
  • the conductive paste was printed so that the internal electrodes located at 1, 2, 299, and 300th in the stacking direction had the first part of the lattice shape as shown in Table 1. .
  • sample number 2 as shown in FIG. 2, the first part of the lattice shape having a square lattice is located on the boundary between the facing part and the non-facing part.
  • sample number 3 as shown in FIG. 3, the lattice-shaped first portion having a circular lattice is positioned on the boundary between the facing portion and the non-facing portion.
  • Sample No. 4 as shown in FIG. 5, the first part having a shape in which the lattice is arranged in a plurality of rows parallel to the boundary between the facing part and the non-facing part is the facing part. Located on the boundary with the non-opposing part.
  • the boundary between the facing portion and the non-facing portion exists at a plurality of locations separated from each other, and the first portion is located on each boundary of the internal electrodes.
  • the internal electrode has a lattice shape and has a first portion and a second portion having a finer lattice than the first portion.
  • part is located on the boundary of an opposing part and a non-opposing part.
  • the raw laminate of each sample number was subjected to a binder removal treatment at a predetermined temperature, and then fired at 800 to 1200 ° C. to obtain a laminate.
  • a conductive paste for an external electrode was prepared by adding and mixing a binder, a plasticizer, glass powder and the like to a metal powder containing silver as a main component. This conductive paste was printed by screen printing or the like on the side surface of the laminate on which the external electrodes were to be formed. Further, an external electrode was formed by baking at 600 to 800 ° C.
  • the drive evaluation was performed using the sample thus prepared. As drive evaluation, high-speed response evaluation and durability evaluation were performed. First, a lead wire is connected to the external electrode 11, 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 a piezoelectric actuator using a laminated piezoelectric element Was made. A DC voltage of 170 V was applied to the obtained piezoelectric actuator, and the amount of displacement in the initial state was measured.
  • an AC voltage of 0 V to +170 V was applied to each piezoelectric actuator at a room temperature with the frequency gradually increased from 150 Hz.
  • an AC voltage of 0 V to +170 V was applied to each piezoelectric actuator at a frequency of 150 Hz at room temperature, and a test was continuously performed up to 1 ⁇ 10 9 times.
  • the piezoelectric actuator of sample number 1 emitted a beat sound when the frequency exceeded 1 kHz.
  • the multilayered piezoelectric element of sample number 1 does not have the first portion of each internal electrode, and the cross-sectional area of each internal electrode is constant, so that the piezoelectric body located near the end of the element This is because the deformation of is large. This is probably because the high-speed response was hindered by the large deformation of the piezoelectric body located near the end of the element, and as a result, the frequency of the applied AC voltage could not be followed.
  • the pulse waveform of sample number 1 was confirmed using an oscilloscope “DL1640L” manufactured by Yokogawa Electric Corporation. As a result, harmonic noise was found at a location corresponding to an integer multiple of the drive frequency. confirmed.
  • the multilayer piezoelectric element was cut, and the first internal electrode closest to the end in the stacking direction was observed using a microscope.
  • a part of the portion located between the non-formed portions 7c of the internal electrode on the cut surface was broken. As described above, it is confirmed that, when a part of the internal electrode breaks, stress is absorbed, cracking of the piezoelectric body is suppressed, and peeling of the internal electrode from the piezoelectric body is suppressed. It was done.

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  • Fuel-Injection Apparatus (AREA)
  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)

Abstract

L'invention porte sur un élément piézo-électrique stratifié dans lequel une réduction de la quantité de déplacement résultant d'une excitation à long terme est améliorée. L'élément piézo-électrique stratifié comprend un stratifié comprenant une pluralité de corps piézo-électriques et une pluralité d'électrodes internes qui sont stratifiés de façon alternée, une première électrode externe formée sur la surface de premier côté du stratifié, et une seconde électrode externe formée sur la surface de second côté de celui-ci, les électrodes internes isolées et séparées au niveau des surfaces de premier et second côtés étant agencées de façon alternée de sorte que la pluralité d'électrodes internes sont connectées alternativement avec l'une ou l'autre des première et seconde électrodes externes, le stratifié étant sectionné dans une partie de vis-à-vis dans laquelle des électrodes internes adjacentes se font face dans la direction de stratification et une partie non en vis-à-vis produite le long des faces de premier et second côtés tout en faisant face à une électrode interne sur deux, et au moins une de la pluralité d'électrodes internes ayant, dans cette électrode interne, une pluralité de parties non formées d'électrode interne le long de la frontière de la partie en vis-à-vis et de la partie non en vis-à-vis.
PCT/JP2009/051253 2008-01-29 2009-01-27 Élément piézo-électrique stratifié, et injecteur équipé d'un élément piézo-électrique stratifié et système d'injection de carburant WO2009096381A1 (fr)

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DE102010020192A1 (de) * 2010-05-11 2011-11-17 Epcos Ag Piezoelektrisches Vielschichtbauelement
EP2472620A1 (fr) * 2009-08-27 2012-07-04 Kyocera Corporation Élément piézoélectrique stratifié ainsi que dispositif d'injection et système d'injection de combustible le mettant en oeuvre
JP2013012657A (ja) * 2011-06-30 2013-01-17 Tdk Corp 圧電素子
JP2013012656A (ja) * 2011-06-30 2013-01-17 Tdk Corp 圧電素子

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JPS58196076A (ja) * 1982-05-11 1983-11-15 Nec Corp 電歪効果素子
JPH0235785A (ja) * 1988-07-26 1990-02-06 Hitachi Metals Ltd 積層型変位素子
JP2005005680A (ja) * 2003-05-21 2005-01-06 Denso Corp 圧電アクチュエータ

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JP3587334B2 (ja) * 1997-03-24 2004-11-10 日立金属株式会社 積層型圧電トランス
JP2007157849A (ja) * 2005-12-01 2007-06-21 Denso Corp 積層型圧電素子の製造方法

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JPS58196076A (ja) * 1982-05-11 1983-11-15 Nec Corp 電歪効果素子
JPH0235785A (ja) * 1988-07-26 1990-02-06 Hitachi Metals Ltd 積層型変位素子
JP2005005680A (ja) * 2003-05-21 2005-01-06 Denso Corp 圧電アクチュエータ

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2472620A1 (fr) * 2009-08-27 2012-07-04 Kyocera Corporation Élément piézoélectrique stratifié ainsi que dispositif d'injection et système d'injection de combustible le mettant en oeuvre
EP2472620A4 (fr) * 2009-08-27 2014-08-27 Kyocera Corp Élément piézoélectrique stratifié ainsi que dispositif d'injection et système d'injection de combustible le mettant en oeuvre
DE102010020192A1 (de) * 2010-05-11 2011-11-17 Epcos Ag Piezoelektrisches Vielschichtbauelement
JP2013012657A (ja) * 2011-06-30 2013-01-17 Tdk Corp 圧電素子
JP2013012656A (ja) * 2011-06-30 2013-01-17 Tdk Corp 圧電素子
US9070857B2 (en) 2011-06-30 2015-06-30 Tdk Corporation Piezoelectric element

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