WO2010044396A1 - Élément piézoélectrique stratifié, dispositif d'injection muni de l'élément piézoélectrique stratifié et système d'injection de carburant - Google Patents

Élément piézoélectrique stratifié, dispositif d'injection muni de l'élément piézoélectrique stratifié et système d'injection de carburant Download PDF

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Publication number
WO2010044396A1
WO2010044396A1 PCT/JP2009/067732 JP2009067732W WO2010044396A1 WO 2010044396 A1 WO2010044396 A1 WO 2010044396A1 JP 2009067732 W JP2009067732 W JP 2009067732W WO 2010044396 A1 WO2010044396 A1 WO 2010044396A1
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WIPO (PCT)
Prior art keywords
piezoelectric element
external electrode
layer
slit
laminated
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PCT/JP2009/067732
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English (en)
Japanese (ja)
Inventor
健 岡村
加藤　剛
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京セラ株式会社
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Priority claimed from JP2008266017A external-priority patent/JP5342846B2/ja
Priority claimed from JP2008278123A external-priority patent/JP2010109057A/ja
Application filed by 京セラ株式会社 filed Critical 京セラ株式会社
Publication of WO2010044396A1 publication Critical patent/WO2010044396A1/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
    • H10N30/872—Interconnections, e.g. connection electrodes of multilayer piezoelectric or electrostrictive devices
    • 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 a drive element (piezoelectric actuator), a sensor element or a circuit element using a piezoelectric body, for example.
  • multilayer piezoelectric elements have been required to be able to ensure a large amount of displacement under a large pressure at the same time as miniaturization is advanced. For this reason, it is required that the multilayer piezoelectric element be used under severe conditions in which a higher voltage corresponding to a larger displacement amount is applied and continuous driving is performed for a long time.
  • the external electrode When driving continuously for a long time under high voltage and high pressure conditions, with the driving of the multilayer piezoelectric element, the external electrode joined to the side surface of the multilayer body composed of the internal electrode layer and the piezoelectric body layer, In addition, since stress is applied to the conductive connection member attached to the surface of the external electrode for connecting the external lead wire, the external electrode is peeled off from the side surface of the laminate or the conductive connection member is peeled off from the external electrode. May end up.
  • a slit-like shape is formed in the piezoelectric layer as disclosed in Patent Document 1.
  • a structure in which a stress relaxation portion is provided, or a multilayer piezoelectric element in which a porous layer as a target fracture layer is previously provided in a piezoelectric layer as disclosed in Patent Document 2 has been proposed.
  • an external electrode having a structure in which a plurality of electrodes are combined has been proposed, for example, as disclosed in Patent Document 3, so that the external electrode can be driven even when it is broken by stress.
  • the thermal expansion of the external electrode and the conductive connecting member is different from the thermal expansion of the laminated body due to self-heating by the driving.
  • Stress concentrates at the boundary with a certain part, or stress concentrates at the boundary between a part without an external electrode to which a conductive connecting member is applied and a certain part, and the external electrode is peeled off from the laminate or applied to the external electrode.
  • the drive is lowered without voltage being supplied to the internal electrode layer due to the occurrence of a crack, or the conductive connecting member is peeled off from the external electrode or the conductive connecting member is cracked. is there.
  • a first laminated piezoelectric element includes a laminated body having external electrodes electrically connected to the internal electrode layer on a side surface of a laminated body in which piezoelectric layers and internal electrode layers are alternately laminated.
  • a groove whose bottom does not reach the laminated body is formed in the external electrode.
  • the multilayer piezoelectric element according to the present invention is characterized in that, in the above configuration, the groove is formed in a layer on a surface side of a deepest layer located on the multilayer body side of the external electrode. is there.
  • the multilayer piezoelectric element of the present invention is characterized in that, in each of the above structures, the groove has one end reaching the edge of the external electrode.
  • the groove has a width of the opening on the surface of the external electrode larger than the width of the bottom surface.
  • the multilayer piezoelectric element of the present invention is characterized in that, in each of the above structures, the groove is formed in parallel with the internal electrode layer.
  • the multilayer body in each of the above structures, includes a planned fracture layer that relaxes stress by breaking preferentially over the internal electrode layer during driving, and the groove Is formed in the vicinity of the expected fracture layer.
  • a slit is further formed in the thickness direction of the external electrode so that the external electrode extends along a direction intersecting the stacking direction of the multilayer body. It is characterized by this.
  • a second multilayer piezoelectric element includes a multilayer body in which piezoelectric layers and internal electrode layers are alternately stacked, and is bonded to the side surface of the multilayer body in the stacking direction so as to be electrically connected to the internal electrode layer.
  • a laminated piezoelectric element that includes an external electrode connected to the surface of the external electrode and a conductive connection member that is attached to the surface of the external electrode in a longitudinal direction and connects an external lead wire.
  • a first slit extending in the thickness direction of the conductive connecting member is formed extending in a direction intersecting with the stacking direction of the stacked body.
  • the multilayer piezoelectric element of the present invention is characterized in that, in the above configuration, the first slit extends in a direction perpendicular to the stacking direction of the multilayer body.
  • the first slit reaches the end in the width direction of the conductive connecting member.
  • the first slit extends across both ends in the width direction of the conductive connecting member.
  • the first slit is overlapped with a predetermined fracture layer set in the internal electrode layer or the piezoelectric layer of the multilayer body. It is what.
  • a plurality of the external lead wires are arranged in the stacking direction of the multilayer body, and the first slit is between the external lead wires. It is characterized by that.
  • the first slit is separated from the external lead wire in each of the above configurations.
  • the multilayer piezoelectric element of the present invention in each of the above structures, at least a part of the first slit follows the external lead wire.
  • the first slit is partly inserted between the external lead wire and the external electrode in each of the above-described configurations.
  • the external electrode has a second slit extending in a direction crossing the stacking direction of the stacked body and extending in the thickness direction of the external electrode. It is what.
  • the second slit is connected to the first slit of the conductive connection member in each of the above-described configurations.
  • An ejection device includes a container having an ejection hole and any one of the multilayer piezoelectric elements according to the present invention, and fluid stored in the container is driven from the ejection hole by driving the multilayer piezoelectric element. It is characterized by being discharged.
  • the fuel injection system of the present invention includes a common rail that stores high-pressure fuel, the injection device of the present invention that injects the high-pressure fuel stored in the common rail, a pressure pump that supplies the high-pressure fuel to the common rail, and the injection And an injection control unit for supplying a drive signal to the apparatus.
  • the groove whose bottom does not reach the multilayer body is formed in the external electrode, so that both of the directions in the direction orthogonal to the stacking direction of the multilayer body of the external electrode are formed. Since the groove formed in the external electrode can absorb the stress generated at the boundary between the end portion, that is, the side where the external electrode is not present and the portion where the external electrode is present, the external electrode is peeled off from the multilayer body Or cracks in the laminate can be suppressed. In particular, even when stress is suddenly applied to the laminated body, cracks are generated in the external electrode starting from the groove to relieve the stress, thereby suppressing the occurrence of cracks in the laminated body and external electrodes from the laminated body. Occurrence of peeling can be suppressed.
  • the surface area of the external electrode is increased by the formation of the groove, the self-heating generated in the multilayer body during the driving of the multilayer piezoelectric element is effectively prevented from the surface of the external electrode through the external electrode from the multilayer body. Can be dissipated. As a result, even when the driving is performed for a long time under a high voltage and high pressure condition, it is possible to suppress the peeling of the external electrode and the cracking of the laminated body, so that the amount of displacement can be stabilized.
  • the first slit is formed in the conductive connecting member, so that both ends in the direction orthogonal to the stacking direction of the laminated body of the conductive connecting member.
  • the first slit formed in the conductive connection member can absorb the stress generated at the boundary between the portion without the conductive connection member and the portion with the conductive connection member on the side surface of the laminate. It is possible to suppress the connection member from peeling from the external electrode, peeling from the laminated body together with the external electrode, or cracking in the laminated body.
  • the surface area of the conductive connecting member is increased by forming the first slit, the self-heating generated in the laminated body during driving of the laminated piezoelectric element is conducted from the laminated body through the conductive connecting member. Can be effectively diffused from the surface of the conductive connecting member. As a result, even when driven for a long time under high voltage and high pressure conditions, it is possible to suppress the peeling of the conductive connecting member and the cracking of the laminated body, so the displacement amount of the laminated piezoelectric element can be stabilized. Can be made.
  • the multilayer piezoelectric element of the present invention is provided as the multilayer piezoelectric element for discharging the fluid stored in the container from the ejection hole, so that the external electrode is peeled off in the multilayer piezoelectric element. And the occurrence of cracks in the laminated body can be prevented, and problems caused by self-heating of the laminated body can be suppressed, so that the desired discharge from the fluid injection holes can be stabilized over a long period of time. Can be done.
  • the injection device of the present invention is provided as a device for injecting the high-pressure fuel stored in the common rail, desired injection of the high-pressure fuel can be stably performed over a long period of time. .
  • FIG. 1 It is a perspective view showing an example of an embodiment of the 1st lamination type piezoelectric element concerning the present invention.
  • (A) is a side view showing another example of the embodiment of the first multilayer piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the first laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA. It is a perspective view which shows an example of embodiment of the 2nd lamination type piezoelectric element which concerns on this invention.
  • (A) is a side view showing an example of an embodiment of a second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along line AA.
  • (A) is a side view showing another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • (A) is a side view showing still another example of the embodiment of the second laminated piezoelectric element according to the present invention, and (b) is a cross-sectional view taken along the line AA.
  • FIG. 1 is a perspective view showing an example of an embodiment of a first laminated piezoelectric element according to the present invention.
  • the multilayer piezoelectric element 1 of this example is electrically connected to the internal electrode layer 5 on the side surface of the multilayer structure 7 in which the piezoelectric layers 3 and the internal electrode layers 5 are alternately stacked.
  • a slit 12 that does not reach the side surface 7 is formed.
  • the surface area of the external electrode 9 is increased by the formation of the groove 12 due to the formation of the groove 12 in the external electrode 9, the self-heating generated in the multilayer body 7 during the driving of the multilayer piezoelectric element 1 is prevented.
  • the laminated body 7 can be effectively dissipated from the surface of the external electrode 9 through the external electrode 9. As a result, even when the driving is performed for a long time under a high voltage and high pressure condition, it is possible to suppress the peeling of the external electrode 9 and the cracking of the laminated body 7, and thus the amount of displacement can be stabilized.
  • Such a groove 12 can effectively relieve stress if the external electrode 9 is easily deformed according to the expansion and contraction of the multilayer body 7 when the multilayer piezoelectric element 1 is driven. It is preferable to provide the grooves 12 in a direction orthogonal to the longitudinal direction of the external electrode 9 that is long in the stacking direction (a direction orthogonal to the stacking direction and along the piezoelectric layer 3 and the internal electrode layer 5).
  • the external electrode 9 is a rectangular shape that is long in the vertical direction of the laminate 7, it is preferable to provide the groove 12 in a direction perpendicular to the longitudinal direction of the external electrode 9, as shown in FIG. Further, if the external electrode 9 is square, it is preferable to provide the groove 12 in a direction orthogonal to the side of the stacked body 7 in the stacking direction. Further, for the S-shaped or crank-shaped external electrode 9, the groove 12 is provided in a direction orthogonal to the longitudinal direction along the stacking direction of the stacked body 7 when the entire external electrode 9 is viewed. Is preferred.
  • the groove 12 whose bottom does not reach the laminated body 7 is preferably formed along a direction orthogonal to the laminating direction of the laminated body 7, that is, in parallel with the internal electrode layer 5. This is because the groove 12 provided in the external electrode 9 is widened or narrowed in the direction in which the multilayer piezoelectric element 1 is driven and the multilayer body 7 expands and contracts, and this deformation causes the deformation. This is because the external electrode 9 can be expanded and contracted together with the laminated body 7, and a stress relaxation effect can be effectively obtained.
  • the external electrode 9 Has a laminated structure in which a plurality of layers are laminated, and the groove 12 is preferably formed in a layer above the deepest layer of the external electrode 9.
  • an external electrode 9 in which a layer (deepest layer) 9A located on the laminated body 7 side and a layer 9B located on the surface side are laminated is shown.
  • the external electrode 9 having a laminated structure in which a plurality of layers are laminated in this manner, even when stress is suddenly applied to the laminated body 7, cracks are caused between the layers of the external electrode 9 with the groove 12 as a starting point. Since the stress can be relieved by causing it to occur, it is possible to achieve both suppression of peeling of the external electrode 9 from the laminate 7 and suppression of cracks in the laminate 7. Further, in the case of the external electrode 9 having a laminated structure, the groove 12 can be formed relatively easily by forming and laminating various patterns of the groove 12 on the layer in which the groove 12 is formed. It is also preferable that the width of the groove 12 can be changed relatively easily.
  • FIGS. 4 (a) and 4 (b) a side view and a cross-sectional view taken along line AA of another example of the embodiment of the first multilayer piezoelectric element according to the present invention, respectively.
  • the external electrode 9 having three or more layers such as a case where the deepest layer 9A located closest to the laminate 7, the layer 9B located on the surface side, and the layer 9C located between them is formed.
  • the layer 9C in contact with the deepest layer 9A is provided with a low-rigidity metal layer made of isolated metal particles.
  • the stress can be relieved by generating cracks in the layer 9 ⁇ / b> C of the external electrode 9 starting from the groove 12, so that the external electrode 9 from the laminate 7 can be relaxed. It is easy to achieve both suppression of peeling and suppression of cracks in the laminate 7 It becomes.
  • FIGS. 3 (a) and 3 (b), respectively, are side views of still another example of the embodiment of the first multilayer piezoelectric element according to the present invention.
  • the AA line cross-sectional view it is preferable that one end of the groove 12 formed in the external electrode 9 and not having the bottom reaching the laminated body 7 reaches the edge of the external electrode 9.
  • the groove 12 whose bottom does not reach the multilayer body 7 is more easily deformed at the edge of the external electrode 9 where stress tends to concentrate. This is because the stress of the external electrode 9 can be effectively relieved. Further, regarding the stress caused by the difference in thermal expansion of the external electrode 9 with respect to the thermal expansion of the laminate 7 due to self-heating by driving, the stress tends to concentrate on the edge of the external electrode 9. By increasing the outer peripheral distance (length along the outer periphery) of the edge of 9 by the groove 12, it can be effectively relaxed.
  • FIG. 2 shows an example in which so-called staggered grooves 12 each having one end reaching the opposing edge of the external electrode 9 are shown.
  • the grooves 12 each having one end reaching the edge are respectively arranged at positions corresponding to the opposite edges.
  • the surface layer of the external electrode 11 has a so-called S-shape, and it is deformed against the expansion and contraction of the laminate 7 as if it were a spring-like movement. Therefore, the stress in the external electrode 9 can be relieved.
  • the external electrodes 9 in which the grooves 12 are formed are symmetrical with respect to the driving direction of the multilayer piezoelectric element 1, that is, the direction of expansion and contraction of the multilayer body 7. Therefore, the multilayer body 7 and the external electrode 9 can be deformed with the axes aligned with respect to the expansion and contraction of the multilayer body 7, and the drive shaft of the multilayer piezoelectric element 1 is prevented from being shaken. Can do.
  • each external electrode 9 has a multilayer body as in the example shown in FIG.
  • the grooves 12 that do not reach 7 are also formed at opposite positions.
  • the stress relaxation locations can be arranged symmetrically with respect to the laminate 7, so that the stress applied to the laminate 7 can be evenly distributed, An excellent stress relaxation effect can be obtained by avoiding stress concentration in one place.
  • the groove 12 whose bottom does not reach the stacked body 7 extends in the stacking direction of the stacked body 7. Since the center of the drive shaft of the multilayer piezoelectric element 1 coincides with the center axis of the multilayer body 7, the drive shaft is not shaken and has high durability.
  • the multilayer piezoelectric element 1 can be obtained.
  • the stress applied to the laminate 7 is evenly distributed. Dispersion not only relieves stress, but also has the advantage that the drive shaft is not shaken, and can suppress self-heating when the multilayer piezoelectric element 1 is driven. Type piezoelectric element 1 can be obtained.
  • the groove 12 whose bottom does not reach the laminated body 7 has a bottom width, that is, a width of the bottom of the external electrode 9 on the bonding surface side with the laminated body 7. It is preferable that the width of the opening on the surface of the external electrode 9 is larger than that.
  • the width of the groove 12 in the layer 9 ⁇ / b> B located on the surface side is larger than the width of the groove 12 in the layer 9 ⁇ / b> C of the external electrode 9.
  • the groove 12 have a larger opening width on the surface of the external electrode 9 than the width of the bottom surface, the heat generated by the stress concentrated on the joint interface between the external electrode 9 and the laminated body 7 is reduced. Through 12, it can be efficiently propagated to the surface of the external electrode 9 toward the opening having a large width and dissipated, and the stress can be relaxed. Further, by efficiently dissipating heat toward the opening having a large width through the groove 12, the stress due to thermal expansion can be suppressed, so that the stress relaxation can be excellent.
  • the width of the opening is made larger than the width of the bottom surface of the groove 12 in this way, the width of the bottom surface is set to 0.05 to 0.5 mm, for example, and the width of the opening is set to 0.1 to 1.5, which is twice to three times. What is necessary is just to set to mm.
  • the width of the opening of the groove 12 that does not reach the laminated body 7 is preferably large on the edge side of the external electrode 9. According to this, stress concentrated on the edge of the external electrode 9 can be effectively relieved by the groove 12 formed with a large opening width toward the edge. Generation
  • production can be suppressed effectively and durability of the lamination type piezoelectric element 1 can be made high. More preferably, the edge of the opening of the groove 12 whose bottom does not reach the laminate 7 is chamfered like a C surface or an R surface, thereby avoiding stress concentration at the opening edge of the groove 12. Can do.
  • the width of the opening of the groove 12 is increased toward the edge of the external electrode 9 as described above, the width of the opening of the groove 12 is set at the edge of the external electrode 9 within the opening of the piezoelectric layer 3.
  • the stress relaxation effect is enhanced by having 10 layers or more. This is because the stress concentrated in the groove 12 can be relaxed by the piezoelectric layer 3 in the opening of the groove 12 being deformed according to the pressure.
  • the stress between the piezoelectric layers 3 can be dispersed, so that stress can be prevented from concentrating on one layer of the piezoelectric layers 3, and the stress can be satisfactorily improved. This is because it can be relaxed.
  • a plurality of grooves 12 whose bottom portions do not reach the stacked body 7 are formed, and an interval between adjacent grooves 12 is on the end side in the stacking direction of the stacked body 7 (upper end side and lower end side). It is preferable that it becomes large toward. This is because the deformation mode at the time of driving the multilayer piezoelectric element 1 expands and contracts in the stacking direction on the end side in the stacking direction of the stacked body 7, but is orthogonal to the stacking direction in the central portion of the stacked body 7. Therefore, stress concentrated on the edge of the external electrode 9 can be relieved by arranging a large number of grooves 12 at the center in the stacking direction, so that the stack 7 is driven by driving the stack 7. The deformation can be increased and the external electrode 9 can be prevented from peeling off from the edge, and the durability of the multilayer piezoelectric element 1 can be enhanced.
  • the distance between the grooves 12 is, for example, the ratio between the interval 1: 2: 4: 8 as 2 n as that, or 3 n by increasing exponentially as can be densely arranged with respect to both end portions of the grooves 12 of the central portion , The stress can be relaxed gradually.
  • FIGS. 6 (a) and 6 (b) and FIGS. 7 (a) and 7 (b) are side views and A-s, respectively, of still another example of the embodiment of the first multilayer piezoelectric element according to the present invention.
  • the groove 12 whose bottom does not reach the laminated body 7 is preferably formed from the edge of the external electrode 9 to the edge facing it.
  • grooves 12 having one end reaching the edge of the external electrode 9 are formed in the upper and lower portions of the external electrode 9 at positions corresponding to the opposite edges, respectively.
  • a groove 12 formed from one edge to the other opposite edge is disposed in the center of the electrode 9.
  • grooves 12 formed from one edge of the external electrode 9 to the other edge are arranged at the upper part and the lower part of the external electrode 9, respectively.
  • the opening of the groove 12 formed from one edge to the other edge widens or narrows, thereby concentrating on the edge of the external electrode 9. Since the stress can be effectively relieved, peeling from the edge of the external electrode 9 and cracking can be prevented, and the durability of the multilayer piezoelectric element 1 can be increased.
  • the groove 12 formed from one edge of the external electrode 9 to the other edge is formed in the central portion of the laminate 7 where the stress is most concentrated.
  • the groove 12 when the groove 12 is arranged as in the example shown in FIG. 7, when the laminated piezoelectric element 1 is housed in a container and used as in an injection device or the like, the container is placed above and below the laminated body 7. By relieving the applied stress by the groove 12, the durability of the multilayer piezoelectric element 1 can be enhanced. In the case of this example as well, when extremely large stress is applied to the external electrode 9 by forming the groove 12 formed from one edge of the external electrode 9 to the other edge on the both ends of the laminate 7. Further, starting from the groove 12, the external electrode 9 can be cracked to relieve the stress.
  • the groove 12 formed in the external electrode 9 and whose bottom does not reach the multilayer body 7 is formed in parallel with the internal electrode layer 5.
  • the groove 12 since the groove 12 can be formed in a direction orthogonal to the electric field applied to the multilayer body 7, the groove 12 is formed in a direction orthogonal to the direction in which the multilayer piezoelectric element 1 is driven and deformed. Since the external electrode 9 is easily expanded and contracted according to the deformation of the multilayer body 7, the stress applied to the external electrode 9 can be relaxed.
  • the internal electrode layer 5 is not formed over the entire surface of the piezoelectric layer 3.
  • the groove 12 corresponds to the inactive region in a direction parallel to the internal electrode layer 5.
  • the laminated piezoelectric element 1 is made highly durable. Can.
  • the groove 12 whose bottom does not reach the laminated body 7 is located between the adjacent internal electrode layers 5.
  • the stress applied to the groove 12 induces deformation of the piezoelectric layer 3 in which the groove 12 is located, and the electromotive force generated by the piezoelectric effect of the piezoelectric layer 3 is transmitted to the adjacent internal electrode layer 5.
  • an effect of correcting the voltage applied to the multilayer piezoelectric element 1 is generated and the driving voltage is lowered, so that a stress relaxation effect is generated in the multilayer piezoelectric element 1.
  • the groove 12 does not reach the internal electrode layer 5, so that a short circuit between the internal electrode layers 5 occurs. There is no.
  • the laminated body 7 includes a planned fracture layer 16 that relieves stress in the multilayer body 7 by breaking preferentially in the multilayer body 7 over the internal electrode layer 5 during driving, and the bottom of the external electrode 9 reaches the multilayer body 7. If the groove 12 not formed is formed in the vicinity of the expected fracture layer 16, the stress is concentrated on the innermost part of the groove 12 (the other end of the groove 12 located in the external electrode 9). Thus, the stress applied to the external electrode 9 can be transmitted to the planned fracture layer 16 through the groove 12, and by breaking the planned fracture layer 16, the stress in the laminate 7 can be relaxed.
  • the multilayer piezoelectric element 1 is used in an environment in which a high load is applied for a long period of time, the piezoelectric body layer 3 is expected to break without causing stress and cracks due to the stress. Stress relaxation in which cracks are effectively generated only in the fault 16 becomes possible, and the multilayer piezoelectric element 1 can be made highly durable. Furthermore, since the fracture can be started with respect to the planned fracture layer 16 from the position where the groove 12 is provided, when the planned fracture layer 16 is provided in the laminate 7, it can be set from which position the fracture is started. Thus, the layout design of the planned fracture layer 16 can be facilitated, and the multilayer piezoelectric element 1 excellent in mass productivity can be obtained. In particular, it is more preferable to form the groove 12 so as to be positioned in the portion of the planned fracture layer 16 because stress can be more effectively concentrated on the planned fracture layer 16.
  • the external electrode 9 in addition, a slit across the thickness direction of the external electrode 9 extends in a direction crossing the stacking direction of the stacked body 7, preferably along a direction orthogonal to the stacking direction (the bottom of the stacked body 7 extends across the thickness direction of the external electrode 9). It is preferable that the reaching slit) 13 is further formed.
  • FIG. 10 (a) and FIG. 10 (b) are side views of still another example of the embodiment of the first laminated piezoelectric element according to the present invention.
  • the sectional view taken along the line AA when the slit 13 is formed in the vicinity of the planned fracture layer 16 included in the laminate 7, the innermost portion of the slit 13 (the slit 13 positioned in the external electrode 9).
  • the stress applied to the external electrode 9 can be transmitted to the planned fracture layer 16 through the slit 13 by utilizing the fact that the stress is concentrated on the other end of the laminate. 7 can be relieved.
  • Such a slit 13 can effectively relieve the stress of the external electrode 9 when set so that the external electrode 9 is easily deformed according to the expansion and contraction of the multilayer body 7 when the multilayer piezoelectric element 1 is driven, Since stress can be concentrated on the innermost part of the slit 13, the planned fracture layer 16 can be effectively broken by disposing the planned fracture layer 16 in the vicinity of the slit 13.
  • the slit 13 is preferably provided in a direction orthogonal to the longitudinal direction of the external electrode 9, that is, in a direction along the piezoelectric layer 3 and the internal electrode layer 5. In particular, it is preferably formed along the direction orthogonal to the stacking direction of the stacked body 7, which is the expansion / contraction direction of the stacked piezoelectric element 1, that is, parallel to the piezoelectric layer 3 and the internal electrode layer 5.
  • the width of the slit 13 is set so that there are 10 or more piezoelectric layers 3 in the slit 13 to increase the stress relaxation effect. This is because the stress concentrated in the slit 13 can be relieved by the piezoelectric layer 3 in the slit 13 being deformed according to the pressure. In particular, since there are ten or more piezoelectric layers 3 in the slit 13, the stress between the piezoelectric layers 3 can be dispersed, so that stress can be prevented from concentrating on one layer of the piezoelectric layer 3. This is because the stress can be relieved well.
  • the length of the slit 13 is preferably less than half of the width of the external electrode 9 in terms of preventing breakage of the external electrode 9 starting from the end of the slit 13.
  • FIG. 11 is a perspective view showing an example of an embodiment of a second laminated piezoelectric element according to the present invention.
  • FIGS. 12A and 12B are a side view and a cross-sectional view taken along line AA of an example of an embodiment of the second laminated piezoelectric element according to the present invention, respectively.
  • the multilayer piezoelectric element 1 of this example is bonded to the side surface of the multilayer body 7 in which the piezoelectric layers 3 and the internal electrode layers 5 are alternately stacked, and is bonded to the inside in the stacking direction.
  • the first piezoelectric element 1 extends in the direction intersecting the stacking direction of the multilayer body 7 to the conductive connecting member 11 and extends in the thickness direction of the conductive connecting member 11 (in the thickness direction of the conductive connecting member 11).
  • a slit 14) is formed that extends to the external electrode 9.
  • FIGS. 12 (a) and 12 (b) the same hatching is applied in both drawings except for the piezoelectric layer 3, and the same hatching is similarly applied in the following similar drawings.
  • the first slit 14 in the conductive connection member 11 By forming the first slit 14 in the conductive connection member 11 in this way, a region that locally deforms in the conductive connection member 11 is formed around the first slit 14, so that the conductive connection is made.
  • the stress applied to the member 11 can be absorbed.
  • cracks are generated in the conductive connection member 11 starting from the first slit 14 to relieve the stress, and the occurrence of cracks in the laminate 7. Suppression and occurrence of peeling of the conductive connecting member 11 from the external electrode 9 or the laminate 7 can be suppressed.
  • the surface area of the conductive connecting member 11 is increased by the amount of the first slit 14 formed.
  • the self-heating generated in the laminated body 7 can be effectively dissipated from the surface of the conductive connecting member 11 through the conductive electrode 11 through the external electrode 9 from the laminated body 7.
  • the amount of displacement of the piezoelectric element 1 can be stabilized.
  • Such a first slit 14 extends in a direction orthogonal to the stacking direction of the stacked body 7 (a direction orthogonal to the stacking direction and along the piezoelectric layer 3 and the internal electrode layer 5). Is preferred. This is because the first slit 14 provided in the conductive connection member 11 is easily deformed by changing the opening width in the direction in which the multilayer body 7 expands and contracts when the multilayer piezoelectric element 1 is driven. This is because the deformation of the first slit 14 makes it possible for the conductive connecting member 11 to expand and contract together with the laminated body 7, and to effectively bring about a stress relaxation effect.
  • the conductive connecting member 11 has a rectangular shape that is long in the vertical direction of the laminated body 7 like the external electrode 9, as shown in FIG. 11, it is orthogonal to the longitudinal direction along the laminated body 7 of the conductive connecting member 11. It is preferable to provide the first slit 14 in the direction in which the first slit 14 is directed. If the conductive connecting member 11 has a square shape, it is preferable to provide the first slit 14 in a direction orthogonal to the side of the stacked body 7 in the stacking direction. Further, the S-shaped or crank-shaped conductive connecting member 11 is also oriented in a direction orthogonal to the longitudinal direction along the stacking direction of the laminate 7 when the entire conductive connecting member 11 is viewed. One slit 14 is preferably provided.
  • the slit 14 reaches the end in the width direction of the conductive connecting member 11, that is, one end of the first slit 14 is at the end (edge) in the width direction of the conductive connecting member 11. This is because when the multilayer piezoelectric element 1 is driven and the multilayer body 7 expands and contracts, the first slit 14 can be more easily deformed at the end of the conductive connecting member 11 where stress tends to concentrate, This is because the stress of the conductive connecting member 11 can be effectively relieved.
  • the slit 14 preferably extends between both ends of the conductive connecting member 11 in the width direction. According to this, since the laminated piezoelectric element 1 is driven and the laminated body 7 expands and contracts, the opening width of the first slit 14 provided in the conductive connecting member 11 is changed over the whole so that it is easily deformed. As a result of this deformation, the conductive connecting member 11 can be expanded and contracted together with the laminated body 7, and the stress relaxation effect can be more effectively brought about.
  • FIGS. 16 (a) and 16 (b) respectively, a side view and a cross-sectional view taken along line AA of another embodiment of the second laminated piezoelectric element according to the present invention
  • external leads A plurality of the wires 18 are arranged in the stacking direction of the stacked body 7, and the first slit 14 is preferably located between the plurality of external lead wires 18. According to this, since the external lead wire 18 can be firmly joined to the conductive connecting member 11, there is an effect that the external lead wire 18 is hardly peeled off.
  • the external lead wires 18 are not shown in FIGS. 11 to 15, but in each example, one or a plurality of external lead wires 18 are arranged in the stacking direction of the stacked body 7 as in the example shown in FIG. It is embedded and connected to the conductive connecting member 11.
  • the external lead wire 18 may be bonded to the surface of the conductive connecting member 11 and connected to the conductive connecting member 11. However, in order to have excellent durability, the example shown in FIG. It is preferably embedded in the conductive connection member 11.
  • the first slit 14 is separated from the external lead wire 18. According to this, since the first slit 14 is away from the external lead wire 18, stress in the multilayer body 7 due to the driving of the multilayer piezoelectric element 1 is not directly applied to the external lead wire 18.
  • the conductive connecting member 11 to which 18 is connected can bring about an effect that it is difficult to peel off from the external electrode 9.
  • the external electrode It is preferable that the second slit 15 in 9 is connected to the first slit 14 of the conductive connection member 11 (overlap in the stacking direction of the external electrode 9 and the conductive connection member 11). According to this, the second slit 15 of the external electrode 9 has an effect of relieving the stress generated in the external electrode 9, and the first slit 14 of the conductive connecting member 11 is further connected to the conductive connecting member 11 at the same position. Therefore, both the external electrode 9 and the conductive connecting member 11 can be effectively separated from the laminate 7.
  • FIG. 21 is a schematic cross-sectional view showing an example of an embodiment of an injection device according to the present invention.
  • the injection device 21 of the present example includes a multilayer piezoelectric element of the present invention represented by the example of the above embodiment inside a storage container (container) 25 having an injection hole 23 at one end. 1 is stored.
  • a needle valve 27 capable of opening and closing the injection hole 23 is disposed in the container 25 in the 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 that it can communicate with the movement of the needle valve 27.
  • the fluid passage 29 is connected to an external fluid supply source, and is supplied with, for example, a liquid that is a fluid at a high pressure at all times. Therefore, when the needle valve 27 opens the injection hole 23 by driving the multilayer piezoelectric element 1, the fluid supplied to the fluid passage 29 is transferred to the outside of the injection hole 23 or a container adjacent to the injection hole 23, for example, an internal combustion engine.
  • the fuel chamber (not shown) is configured to be discharged from the injection hole 23 and injected.
  • the fluid ejection operation is to apply a voltage to the multilayer piezoelectric element 1 to open the fluid passage 29 and discharge the fluid from the ejection hole 23, and to stop applying the voltage to close the fluid passage 29. Thus, the discharge of the fluid may be stopped.
  • the injection device 21 of the present invention includes a container 25 having an injection hole 23 and the multilayer piezoelectric element 1 of the present invention, and the fluid filled in the container 25 is ejected by driving the multilayer piezoelectric element 1. It may be configured to discharge from 23. That is, the multilayer piezoelectric element 1 does not necessarily have to be inside the container 25, and the pressure for supplying and stopping the fluid to the injection hole 23 is applied to the inside of the container 25 by driving the multilayer piezoelectric element 1. It suffices to be configured.
  • the fluid including the liquid is not only supplied to the injection hole 23 through the fluid passage 29, but also provided in the container 25 with a portion for temporarily storing the fluid in an appropriate place in the container 25. The filled fluid may be discharged from the injection hole 23.
  • the fluid includes various liquid materials (such as conductive paste) and gas, as well as liquid such as fuel or ink.
  • liquid such as fuel or ink.
  • FIG. 22 is a schematic diagram showing an example of an embodiment of a fuel injection system according to the present invention.
  • the fuel injection system 41 of this example includes a common rail 43 that stores high-pressure fuel, a plurality of injection devices 21 of the present invention that inject high-pressure fuel stored in the common rail 43, and a high pressure to the common rail 43.
  • a pressure pump 45 for supplying fuel and an injection control unit 47 for supplying a drive signal to the injection device 21 are provided.
  • the injection control unit 47 controls the amount and timing of high-pressure fuel injection based on external information or an external signal. For example, in the case of the injection control unit 47 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 serves to supply fluid fuel from the fluid tank 49 to the common rail 43 at a high pressure.
  • fluid fuel is fed into the common rail 43 at a high pressure of about 1000 to 2000 atmospheres, preferably about 1500 to 1700 atmospheres.
  • the high-pressure fuel sent from the pressure pump 45 is stored and appropriately sent to the injection device 21 in accordance with the driving of the multilayer piezoelectric element 1.
  • the injection device 21 discharges (injects) high-pressure fuel, which is a predetermined amount of fluid, from the injection hole 23 to the outside of the injection hole 23 or a container adjacent to the injection hole 23 at high pressure.
  • high-pressure fuel which is a fluid
  • 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, for example, a printing device of an ink jet printer, a pressure sensor, or the like Even if it is what is used for, if it is a laminated type piezoelectric element using a piezoelectric characteristic, it can implement by the same structure.
  • a ceramic green sheet to be the piezoelectric layer 3 is produced. Specifically, a calcined powder of piezoelectric ceramic, a binder made of an organic polymer such as acrylic or butyral, and a plasticizer are mixed to prepare a slurry. And a ceramic green sheet is produced by using tape molding methods, such as a doctor blade method and a calender roll method, for this slurry.
  • 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 DBP (dibutyl phthalate), DOP (dioctyl phthalate), or the like can be used.
  • the carbon powder is included in the conductive paste, and the carbon powder is baked during firing.
  • the conductive paste of the porous metal particle layer to be the planned fracture layer 16 and other By changing the metal component ratio of the internal electrode layer 5 with the conductive paste and utilizing the concentration difference during firing, the metal is transferred from the planned fracture layer 16 to the adjacent internal electrode layer 5 via the piezoelectric layer 3. It can be made porous by diffusing. This method is preferable in terms of excellent mass productivity.
  • a conductive paste mainly composed of silver-palladium is used and the silver concentration of the layer to be the expected fracture layer 16 is higher than the silver concentration of the other internal electrode layers 5, the silver forms a liquid phase during firing. At the same time, since it can easily move between the piezoelectric particles of the piezoelectric layer 3, it is possible to form the expected fracture layer 16 composed of a very uniform porous metal particle layer.
  • the external electrode 9 is formed on the outer surface of the multilayer body 7 of the multilayer piezoelectric element 1 so as to obtain conduction with the internal electrode layer 5 whose end is exposed.
  • the external electrode 9 can be obtained by adding a binder to silver powder and glass powder to produce a silver glass conductive paste, printing this on the side surface of the laminate 7, drying and adhering, or baking.
  • a method of forming a multilayer pattern by printing a silver glass conductive paste is most mass-produced.
  • the deepest layer 9A is formed on the deepest layer 9A by screen printing.
  • a layer 9C located between the layer 9B located on the surface side in which the pattern is hollowed out in the shape of the groove 12 and a layer 9B located in the surface side similarly in the shape of the groove 12 are laminated in order.
  • the width of the opening can be made larger than the width of the bottom surface of the groove 12 by printing with the opening width of the groove 12 being increased in the pattern of the upper layer (layer 9C and layer 9B) to be laminated. .
  • the groove whose bottom does not reach the laminated body 7 after the external electrode 9 is formed by a printing method, a vapor deposition method or the like.
  • a method of etching into a pattern of 12 similarly, a method of carrying out sand blasting or dry ice blasting by placing a metal mask provided with a pattern of the shape of the groove 12 whose bottom does not reach the laminated body 7 after forming the external electrode 9;
  • a lead wire made of a metal wire, a conductive member made of a metal mesh or a mesh-like metal plate, etc. are joined and fixed to the surface of the external electrode 9 using a bonding material such as solder or conductive adhesive.
  • a bonding material such as solder or conductive adhesive.
  • the material of the conductive member is preferably a metal or alloy such as silver, nickel, copper, phosphor bronze, iron, and stainless steel.
  • the surface of the conductive member may be plated with silver or nickel.
  • the conductive member may be joined over the entire lamination direction of the external electrodes 9 or may be joined to a part of the external electrodes 9.
  • the laminate 7 on which the external electrodes 9 are 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, the silicone resin is coated on the side surface of the laminate 7 on which the external electrode 9 having the grooves 12 is formed.
  • a direct current voltage of 0.1 to 3 kV / mm is applied from the pair of external electrodes 9 to the piezoelectric layer 3 through the conductive member connected to the external electrode 9 by the internal electrode layer 5, and the piezoelectric layer 3 of the multilayer body 7 is applied.
  • the laminated piezoelectric element 1 of this example is completed.
  • the conductive member is connected to an external voltage supply unit, and a voltage is applied to the piezoelectric layer 3 by the internal electrode layer 5 via the conductive member and the external electrode 9, whereby each piezoelectric layer 3 is caused to have an inverse piezoelectric effect. It can be displaced greatly.
  • it is possible to function as an automobile fuel injection valve mechanism for injecting and supplying fuel to the engine.
  • the external electrode is connected to the internal electrode layer 5 whose end is exposed on the outer surface of the multilayer body 7 of the multilayer piezoelectric element 1. Since the process up to the step 9 is the same as that of the first method for manufacturing a laminated piezoelectric element according to the present invention, the description thereof is omitted.
  • a pattern printing method is most mass-produced so as to form the second slit 10 when the silver glass conductive paste is printed.
  • a method of etching the pattern of the second slit 12 after forming the external electrode 9 a method of performing sandblasting or dry ice blasting with a metal mask provided with a pattern of the shape of the second slit 10, Alternatively, there is a method of dicing using a diamond disk.
  • the conductive connecting member 11 is attached to the surface of the external electrode 9 in the longitudinal direction.
  • the conductive connecting member 11 is attached in the longitudinal direction by applying a conductive bonding agent such as solder or conductive adhesive to the surface of the external electrode 9 by applying it in accordance with the shape of the external electrode 9.
  • a lead wire made of a metal wire, an external lead wire 14 made of a metal mesh, a mesh-like metal plate, or the like is joined and fixed to the surface of the external electrode 9.
  • the material of the external lead wire 14 is preferably a metal or alloy such as silver, nickel, copper, phosphor bronze, iron or stainless steel. Further, the surface of the external lead wire 14 may be plated with silver, nickel, or the like.
  • the external lead wire 14 may be connected over the entire stacking direction of the external electrode 9 by the conductive connection member 11 or may be connected to a partial region of the external electrode 9.
  • a method of etching after forming the conductive connecting member 11 There are a method of carrying out sand blasting or dry ice blasting with a metal mask provided with a shape pattern, or a method of dicing using a diamond disk.
  • the laminate 7 in which the conductive connection member 11 is formed and the external lead wire 14 is connected 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, the silicone resin as the exterior resin is coated on the side surface of the laminate 7 on which the conductive connecting member 11 having the slits 12 is formed.
  • each piezoelectric layer 3 can be largely displaced by the inverse piezoelectric effect.
  • it is possible to function as an automobile fuel injection valve mechanism for injecting and supplying fuel to the engine.
  • a slurry is prepared by mixing a binder powder and a plasticizer with a raw material powder mainly composed of lead zirconate titanate (PZT) powder having an average particle diameter of 0.4 ⁇ m, and a ceramic green sheet having a thickness of 150 ⁇ m is prepared by a doctor blade method.
  • PZT lead zirconate titanate
  • a conductive paste B was prepared by adding a binder to the powder.
  • the raw laminate of each sample number was subjected to binder removal treatment at a predetermined temperature, and then fired at 800 to 1000 ° C. to obtain a laminate 7.
  • the layer using the conductive paste B As a result, the expected fracture layer 16, which is a low-rigidity metal layer made of isolated metal particles, was formed.
  • a conductive paste C was prepared by adding and mixing a binder, a plasticizer, a glass powder and the like to a metal powder containing silver as a main component.
  • a conductive paste D was prepared by adding and mixing a binder and a plasticizer to metal powder containing silver as a main component.
  • the shape of the groove 12 whose bottom did not reach the laminated body 7 was such that the opening width was about 10% larger than the width of the bottom surface. This is because the pattern edge portion of the conductive paste immediately after is rounded by the surface tension, so that the edge of the opening is chamfered. Since the shape of the bottom surface of the groove 12 whose bottom does not reach the laminated body 7 is a rectangular shape, the width and length of the bottom surface of the rectangular shape are shown in the dimension column of Table 1 as width ⁇ length. As shown.
  • the drive evaluation was performed using each 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 9, and a polarization treatment is performed by applying a DC voltage of 3 kV / mm for 15 minutes from the positive electrode and the negative external electrode 9 to the piezoelectric layer 3 via the lead wire. A piezoelectric actuator using the element 1 was produced. A DC voltage of 170 V was applied to the obtained piezoelectric actuator, and the amount of displacement in the initial state was measured.
  • the pulse waveform of the drive signal of sample number 1 was confirmed using an oscilloscope DL1640L manufactured by Yokogawa Electric Corporation, and harmonic noise was confirmed at a location corresponding to an integer multiple of the drive frequency. It was done. Regarding this, in Table 1, “present” is shown in the column of noise generation of harmonic components.
  • the piezoelectric actuators of sample numbers 2 to 6 which are the examples of the present invention the external electrode 9 and the laminated portion in the laminated body 7 are peeled off after continuous driving (1 ⁇ 10 9 times). There wasn't.
  • the piezoelectric actuators of Sample Nos. 4 to 6 which are the embodiments of the present invention have a very high durability because no decrease in the displacement amount is confirmed even after continuous driving of 1 ⁇ 10 9 times. I understood that.
  • the planned fracture layer 16 was cracked. Since it was confirmed that the position of the crack was the portion where the groove 12 where the bottom did not reach the laminated body 7 was provided, the expected fracture layer 16 was preferentially broken by using the groove 12, and the stress in the laminated body 7 was Was confirmed.
  • the layer 9C of the external electrode 9 is formed of a low-rigidity metal layer made of isolated metal particles.
  • the external electrode that is the low-rigidity metal layer Nine layers 9C were cracked. Since it was confirmed that the position of the crack was only in the layer 9C of the external electrode 9 starting from the portion where the groove 12 was provided, the layer 9C of the external electrode 9 formed of a low-rigidity metal layer by using the groove 12 was confirmed. Was preferentially broken, and it was confirmed that the stress in the laminate 7 was relaxed.
  • a slurry is prepared by mixing a binder powder and a plasticizer with a raw material powder mainly composed of lead zirconate titanate (PZT) powder with an average particle size of 0.4 ⁇ m, and a ceramic green sheet with a thickness of 150 ⁇ m is prepared by the doctor blade method. did.
  • PZT lead zirconate titanate
  • a conductive paste B was prepared by adding a binder to the powder.
  • the conductive paste A was printed on one side of the ceramic green sheet with a pattern of the internal electrode layer 5 so as to have a thickness of 30 ⁇ m by screen printing. And each green ceramic sheet on which conductive paste A was printed was laminated to produce a green laminate.
  • the number of laminated layers the number of internal electrode layers 5 is laminated to be 300, and only 20 ceramic green sheets on which no conductive paste is printed are provided at both ends in the lamination direction of the green laminate. Laminated to give sample numbers 11-20.
  • the internal electrode layers 5 located at the 50th and 250th positions in the stacking direction are electrically conductive. Printing was performed using the adhesive paste B.
  • the raw laminate of each sample number was subjected to binder removal treatment at a predetermined temperature, and then fired at 800 to 1000 ° C. to obtain a laminate 7.
  • the electrode component silver of the layer using the conductive paste B diffused into the adjacent metal layer having a low silver concentration during the firing, so that the layer using the conductive paste B A planned fracture layer 16, which is a low-rigidity metal layer made of isolated metal particles, was formed.
  • sample numbers 19 and 20 have external electrodes 9 respectively so that the second slit 15 can be formed.
  • a conductive paste C for the external electrode 9 was prepared by adding and mixing a binder, a plasticizer, glass powder, and the like to metal powder containing silver as a main component. This conductive paste C was printed in a rectangular pattern extending in the stacking direction of the multilayer body 7 by screen printing or the like at a location where the rectangular side surface of the multilayer body 7 was to be formed.
  • the external electrode 9 was formed by baking at 600 to 800 ° C. At this time, the external electrode 9 is formed on the side surface of the multilayer body 7 in the longitudinal direction in the laminating direction, and the second slit 15 is a predetermined fracture layer that is the internal electrode layer 5 located at the 50th and 250th positions in the laminating direction. At a position overlapping with 16, the width (width in the stacking direction) ⁇ length (length in the direction orthogonal to the stacking direction) was set to a size of 0.5 mm ⁇ 3 mm in a direction orthogonal to the stacking direction.
  • the first slit 14 was not formed as a comparative example of the present invention.
  • the conductive connecting member 11 at a position overlapping the 50th and 250th internal electrode layers 5 in the stacking direction of the stacked body 7 is connected to the first of 0.5 mm in width and 1 mm in length in the direction perpendicular to the stacking direction.
  • the slit 14 was formed so as to be accommodated in the conductive connecting member 11.
  • a conductive slit 11 on the internal electrode layer 5 at the same position as Sample No. 12 is provided with a first slit 14 having a width of 0.5 mm and a length of 1 mm in a direction perpendicular to the stacking direction at one end. Was formed so as to reach the end of the external electrode 9.
  • the conductive slit 11 on the internal electrode layer 5 at the same position as the sample number 12 is provided with a first slit 14 having a width of 0.5 mm and a length of 3 mm in the direction perpendicular to the stacking direction. It formed so that it might reach from the end to the end.
  • the conductive connecting member 11 has a width of 0.5 mm ⁇ a length of 3 mm in a direction perpendicular to the stacking direction so as to overlap the 50th and 250th planned fracture layers 13 in the stacking direction of the stacked body 7.
  • the first slit 14 was formed so as to reach the end of the external electrode 9.
  • the first slit 14 was not provided in the conductive connecting member 11.
  • the external electrode 9 and the conductive connection member 11 are 0.5 mm wide by 3 mm long in a direction perpendicular to the laminating direction so as to overlap the 50th and 250th expected fracture layers 16 in the laminating direction.
  • the second slit 15 was formed from the end of the external electrode 9 to the end, and the first slit 14 having a width of 0.5 mm and a length of 3 mm was also formed from the end of the external electrode 9 to the end.
  • the laminate 7 in which the external electrode 9 was formed and the conductive connection member 11 was adhered was 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 irregularities on the outer peripheral side surface of the laminate 7, and then the laminate 7 is pulled up from the silicone resin solution to be externally attached to the side surface of the laminate 7. A silicone resin was formed as the resin.
  • the drive evaluation was performed using each sample thus prepared. As drive evaluation, high-speed response evaluation and durability evaluation were performed. First, a polarization process is performed by applying a DC voltage of 3 kV / mm for 15 minutes from the internal electrode layer 5 to the piezoelectric layer 3 through the external lead wire 18, the conductive connecting member 11 and the external electrode 9, so that the laminated piezoelectric element A piezoelectric actuator using No. 1 was produced. A DC voltage of 170 V was applied to the obtained piezoelectric actuator, and the amount of displacement in the initial state was measured.
  • the pulse waveform of the drive signal of sample number 11 was confirmed using the Yokogawa oscilloscope DL1640L, and harmonic noise was confirmed at a location corresponding to an integer multiple of the drive frequency. It was done. This is indicated by “occurrence” in the noise column of the harmonic component in Table 4.
  • peeling was observed in a part of the conductive connecting member 11 and a part of the external electrode 9 after continuous driving (1 ⁇ 10 9 times). Cracks were observed in some of the areas.
  • the conductive connecting member 11 is peeled off, the external electrode 9 is peeled off, and the laminated body 7 after continuous driving (1 ⁇ 10 9 times). Cracks in the laminated part were not confirmed.
  • the stress applied to the conductive connecting member 11 is increased when the laminate 7 is expanded or contracted. Since it can be transmitted to the planned fracture layer 16 through the first slit 14 and the stress in the laminate 7 can be relaxed by breaking the planned fracture layer 16, it is displaced even after 1 ⁇ 10 9 cycles. The decrease in the amount was in the 6% range and 10% or less, and it was found that the amount was extremely high. Further, in the piezoelectric actuator of sample number 20, the second slit 15 of the external electrode 9 has an effect of relieving the stress generated in the external electrode 9, and further, the first slit 14 of the conductive connecting member 11 at the same location.
  • the laminated piezoelectric elements of sample numbers 15 to 20 had cracks in the expected fracture layer 16. This is because the stress is concentrated at the position where the first slit 14 is provided on the conductive connecting member 11 or at the position where the second slit 15 is provided on the external electrode 9 so that they overlap. The stress was transmitted to the planned fracture layer 16 and the fracture was started. From this, it was confirmed that the provisional fracture layer 16 was preferentially broken by providing the first slit 14 in the conductive connecting member 11, and the stress in the laminate 7 was relaxed.

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  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

Il existe un problème avec les éléments piézoélectriques stratifiés classiques concernant la durabilité en ce que les éléments piézoélectriques stratifiés ne sont pas excités de façon stable en raison du fait qu'une électrode externe ne peut pas absorber une contrainte et se décolle et que des fissures apparaissent dans un corps stratifié, dans le cas où les quantités de déplacement des éléments sont grandes et/ou les éléments sont excités à des vitesses élevées. L'invention porte sur un élément piézoélectrique stratifié (1) dans lequel une électrode externe (9) électriquement connectée à une couche d'électrode interne (5) est formée sur la surface latérale d'un corps stratifié (7) dans lequel des couches piézoélectriques (3) et les couches d'électrode interne (5) sont alternativement stratifiées. Sur l'électrode externe (9) dans l'élément piézoélectrique stratifié (1), une rainure (12) dont le fond n'atteint pas le corps stratifié (7) est formée. Des contraintes peuvent être relaxées et l'enlèvement de l'électrode externe (9) et l’apparition de fissures dans le corps stratifié (7) peuvent être supprimés étant donné que la rainure (12) dont le fond n'atteint pas le corps stratifié (7) est formée sur l'électrode externe (9), et un élément piézoélectrique stratifié (1) disposant d’une excellente durabilité est obtenu.
PCT/JP2009/067732 2008-10-15 2009-10-13 Élément piézoélectrique stratifié, dispositif d'injection muni de l'élément piézoélectrique stratifié et système d'injection de carburant WO2010044396A1 (fr)

Applications Claiming Priority (4)

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JP2008266017A JP5342846B2 (ja) 2008-10-15 2008-10-15 積層型圧電素子およびこれを備えた噴射装置ならびに燃料噴射システム
JP2008-266017 2008-10-15
JP2008-278123 2008-10-29
JP2008278123A JP2010109057A (ja) 2008-10-29 2008-10-29 積層型圧電素子およびこれを備えた噴射装置ならびに燃料噴射システム

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
JP2012079814A (ja) * 2010-09-30 2012-04-19 Taiheiyo Cement Corp 圧電素子
US20130193810A1 (en) * 2012-01-27 2013-08-01 Tdk Corporation Laminated piezoelectric device

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