WO2018020921A1 - Stacked piezoelectric element, injection device equipped with same, and fuel injection system - Google Patents

Stacked piezoelectric element, injection device equipped with same, and fuel injection system Download PDF

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Publication number
WO2018020921A1
WO2018020921A1 PCT/JP2017/023152 JP2017023152W WO2018020921A1 WO 2018020921 A1 WO2018020921 A1 WO 2018020921A1 JP 2017023152 W JP2017023152 W JP 2017023152W WO 2018020921 A1 WO2018020921 A1 WO 2018020921A1
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Prior art keywords
internal electrode
electrode layer
piezoelectric element
viewed
stacking direction
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PCT/JP2017/023152
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French (fr)
Japanese (ja)
Inventor
新作 里井
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京セラ株式会社
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Application filed by 京セラ株式会社 filed Critical 京セラ株式会社
Priority to JP2018529448A priority Critical patent/JP6698843B2/en
Publication of WO2018020921A1 publication Critical patent/WO2018020921A1/en

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    • 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
    • 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
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/02—Conduits between injection pumps and injectors, e.g. conduits between pump and common-rail or conduits between common-rail and injectors
    • 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
    • H10N30/01—Manufacture or treatment
    • H10N30/02—Forming enclosures or casings
    • 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
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • 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
    • 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
    • H10N30/88—Mounts; Supports; Enclosures; Casings

Definitions

  • the present disclosure relates to a laminated piezoelectric element used as a piezoelectric driving element (piezoelectric actuator), a pressure sensor element, a piezoelectric circuit element, and the like, an injection apparatus including the same, and a fuel injection system.
  • the laminated piezoelectric element has a laminate in which the first internal electrode layers and the second internal electrode layers are alternately laminated via the piezoelectric layers, and a covering material provided on the side surface of the laminate. Things are known.
  • the stacked piezoelectric element includes an active region in which the first internal electrode layer and the second internal electrode layer overlap each other when viewed from the stacking direction, and the first internal electrode layer and the second internal electrode when viewed from the stacking direction.
  • One having an inactive region that does not overlap with a layer is known (see, for example, Patent Document 1).
  • the multilayer piezoelectric element of the present disclosure includes a multilayer body in which first internal electrode layers and second internal electrode layers are alternately stacked via piezoelectric layers.
  • the stacked body includes an active region in which the first internal electrode layer and the second internal electrode layer overlap each other when viewed from the stacking direction, and the first internal electrode layer and the second internal electrode when viewed from the stacking direction. And an inactive region that does not overlap the layer.
  • the multilayer body has a first side surface to which both end faces of the first internal electrode layer and the second internal electrode layer reach.
  • the multilayer piezoelectric element includes a coating material that covers at least the first side surface of the multilayer body, and the thickness of the coating material that covers the first side surface when viewed from the stacking direction is the active material. It is thicker in the vicinity of the boundary between the active region and the inactive region than the central portion of the region.
  • the injection device of the present disclosure includes a container having an injection hole and the multilayer piezoelectric element described above, and the injection hole is opened and closed by driving the multilayer piezoelectric element.
  • the fuel injection system of the present disclosure includes a common rail that stores high-pressure fuel, the above-described injection device 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 An injection control unit for supplying a drive signal to the apparatus.
  • FIG. 2 is an exploded view of the multilayer piezoelectric element shown in FIG. 1.
  • FIG. 2 is a plan view of the multilayer piezoelectric element shown in FIG. 1.
  • It is a top view of other examples of a lamination type piezoelectric element.
  • It is a top view of other examples of a lamination type piezoelectric element.
  • It is a top view of other examples of a lamination type piezoelectric element.
  • It is a top view of other examples of a lamination type piezoelectric element.
  • It is a top view of other examples of a lamination type piezoelectric element.
  • It is a perspective view of the other example of a lamination type piezoelectric element.
  • FIG. 10 is an exploded view of the multilayer piezoelectric element shown in FIG. 9.
  • FIG. 10 is a plan view of the multilayer piezoelectric element shown in FIG. 9. It is a schematic sectional drawing showing an example of an embodiment of an injection device.
  • 1 is a schematic block diagram illustrating an example of an embodiment of a fuel injection system.
  • the present disclosure has been made in view of the above circumstances, and an object thereof is to provide a multilayer piezoelectric element that suppresses dielectric breakdown of a multilayer body and has excellent long-term reliability, an injection device including the multilayer piezoelectric element, and a fuel injection system. To do.
  • FIG. 1 is a perspective view showing an example of an embodiment of a multilayer piezoelectric element
  • FIG. 2 is an exploded view of the multilayer piezoelectric element shown in FIG. 1
  • FIG. 3 is a plan view of the multilayer piezoelectric element shown in FIG.
  • the multilayer piezoelectric element 1 shown in FIGS. 1 to 3 includes a multilayer body 10 in which first internal electrode layers 121 and second internal electrode layers 122 are alternately stacked with piezoelectric layers 11 interposed therebetween.
  • the stacked body 10 includes an active region 13 where the first internal electrode layer 121 and the second internal electrode layer 122 overlap as viewed from the stacking direction, and the first internal electrode layer 121 and the second internal electrode viewed from the stacking direction.
  • the inactive region 14 that does not overlap the electrode layer 122 is provided.
  • the stacked body 10 has a first side surface 151 that reaches both end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122.
  • the multilayer piezoelectric element 1 includes the covering material 16 that covers at least the first side surface 151 of the multilayer body 10, and the thickness of the covering material 16 that covers the first side surface 151 is viewed from the stacking direction.
  • the thickness is thicker in the vicinity of the boundary between the active region 13 and the inactive region 14 than the central portion of the active region 13.
  • the laminated body 10 constituting the laminated piezoelectric element 1 is obtained by alternately laminating first internal electrode layers 121 and second internal electrode layers 122 with the piezoelectric layers 11 interposed therebetween.
  • the stacked body 10 includes an active region 13 where the first internal electrode layer 121 and the second internal electrode layer 122 overlap each other when viewed from the stacking direction, and the first internal electrode layer 121 and the second internal electrode layer viewed from the stacking direction.
  • the inactive region 14 does not overlap with the internal electrode layer 122.
  • the active region 13 is a portion that expands or contracts in the stacking direction during driving.
  • the inactive region 14 is a portion that does not stretch or shrink in the stacking direction during driving or is difficult to do.
  • the laminated body 10 includes a portion where the first internal electrode layers 121 and the second internal electrode layers 122 are alternately laminated via the piezoelectric layers 11 and the piezoelectric layers 11 provided at both ends in the lamination direction. Only the laminated part.
  • the portions where only the piezoelectric layers 11 positioned at both ends in the stacking direction are stacked are also portions that do not expand or contract in the stacking direction during driving.
  • the laminated body 10 has, for example, a rectangular column shape (a rectangular parallelepiped shape) having a length of 0.5 mm to 10 mm, a width of 0.5 mm to 10 mm, and a height of 1 mm to 100 mm.
  • the laminated body 10 may have a hexagonal prism shape, an octagonal prism shape, a cylindrical shape, or the like.
  • the piezoelectric layer 11 constituting the laminate 10 is made of ceramics having piezoelectric characteristics.
  • a ceramic for example, a perovskite oxide made of lead zirconate titanate (PbZrO 3 —PbTiO 3 ), lithium niobate (LiNbO 3 ), lithium tantalate (LiTaO 3 ), or the like can be used.
  • the thickness of the piezoelectric layer 11 is, for example, 3 ⁇ m to 250 ⁇ m.
  • the first internal electrode layer 121 and the second internal electrode layer 122 constituting the laminated body 10 are formed by simultaneous firing with the ceramic forming the piezoelectric layer 11.
  • the first internal electrode layers 121 and the second internal electrode layers 122 are alternately stacked with the piezoelectric layers 11 to sandwich the piezoelectric layers 11 from above and below.
  • a driving voltage is applied to the piezoelectric layer 11 sandwiched therebetween.
  • a conductor mainly composed of a silver-palladium alloy or a conductor containing copper, platinum, or the like can be used.
  • the first internal electrode layer 121 and the second internal electrode layer 122 are alternately drawn out to a pair of opposing side surfaces of the stacked body 10 and provided on the side surfaces of the stacked body 10 described later.
  • a pair of external electrodes 17 are electrically connected.
  • the thickness of the first internal electrode layer 121 and the second internal electrode layer 122 is, for example, 0.1 ⁇ m to 5 ⁇ m.
  • the side surface (second side surface 152) reached by either one of the first internal electrode layer 121 and the second internal electrode layer 122 is the first internal electrode layer 121 and the second internal electrode layer.
  • Reference numerals 122 denote a pair of opposing side surfaces of the stacked body 10 drawn alternately.
  • a pair of opposing side surfaces other than the second side surface 152 (a pair of opposing side surfaces) of the stacked body 10 is a first side surface 151, and the first internal electrode layer 121 and the first side surface 151 are provided on the first side surface. Both end faces of the second internal electrode layer 122 reach.
  • the laminated body 10 may include a metal layer that is a layer for relaxing stress and does not function as an internal electrode layer.
  • external electrodes 17 are provided on the second side surfaces 152 that reach one of the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122, respectively, and the first internal electrode layer 121 drawn out is provided. Alternatively, it is electrically connected to the second internal electrode layer 122.
  • the external electrode 17 can be produced by baking a conductive paste containing a metal such as silver or copper.
  • the thickness of the external electrode 17 is set to 5 ⁇ m to 70 ⁇ m.
  • a lead member is joined to the end of the external electrode 17, and electrical connection with an external circuit is made through the lead member.
  • the multilayer piezoelectric element 1 includes a covering material 16 that covers at least the first side surface 151 of the multilayer body 10.
  • the thickness of the covering material 16 is larger in the vicinity of the boundary between the active region 13 and the inactive region 14 than in the central portion of the active region 13 when viewed from the stacking direction of the stacked body 10.
  • the central part of the active region 13 when viewed from the stacking direction of the stacked body 10 is strictly located inside the stacked body 10, the active region 13 when viewed from the stacking direction referred to here.
  • the central portion is the central portion of the active region 13 facing the first side surface 151 when viewed from the stacking direction, in other words, the first internal electrode layer 121 and the second internal electrode layer on the first side surface 151. It means the central part of the part where 122 reaches.
  • the first internal electrode layer 121 and the second internal electrode layer 122 are extended from the opposite second side surfaces 152 alternately toward the inside of the stacked body 10.
  • the central portion of the active region 13 when viewed from the stacking direction is located at the center of the first side surface 151.
  • the vicinity of the boundary between the active region 13 and the inactive region 14 in the covering material 16 is a portion of the side surface on which the covering material 16 is provided that faces the boundary between the active region 13 and the inactive region 14 and its vicinity region. It means that. Specifically, when the laminate 10 is viewed in plan, it is within 1/10 of the length (width) of the side surface from the boundary between the active region 13 and the inactive region 14 on the side surface on which the covering material 16 is provided. The range is set near the boundary between the active region 13 and the inactive region 14.
  • the covering material 16 is made of, for example, a silicone resin, an epoxy resin, a nylon resin, or the like, and may be composed of not only a single layer but also a plurality of layers.
  • the covering material 16 has an effect of suppressing migration and discharge on the first side surface 151 of the stacked body 10 that both end faces of the first internal electrode layer 121 and the second internal electrode layer 122 reach.
  • the covering material 16 is provided so as not to cover and expose the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 only on the first side surface 151. Yes.
  • the thickness of the covering material 16 is thin at the center of the active region 13 that well follows expansion and contraction by driving, and the active region 13 and the inactive region 14 where stress concentrates. In the vicinity of the boundary, the covering material 16 is thick. Thereby, the distortion which arises between the active region 13 and the inactive region 14 can be made small, and stress can be reduced. Therefore, it is possible to suppress the generation of cracks in the laminated body 10 and suppress dielectric breakdown. Therefore, the multilayer piezoelectric element 1 having excellent long-term reliability can be obtained.
  • the thickness of the covering material 16 is set to, for example, 20 ⁇ m to 400 ⁇ m at a relatively thin portion facing the central portion of the active region 13, and is relatively opposed to the vicinity of the boundary between the active region 13 and the inactive region 14.
  • the thickness is 1.1 to 5.0 times the thickness of the thin portion.
  • the relatively thick portion facing the vicinity of the boundary between the active region 13 and the inactive region 14 is a protrusion (projection) extending in the stacking direction having a rectangular cross section. It is not limited to such a protrusion.
  • it may be a protrusion (ridge portion) extending in the stacking direction in a cross-sectional shape such that the width becomes narrower toward the tip when viewed in cross section.
  • the thickness of the covering material 16 can be changed gently when viewed from the stacking direction of the stacked body 10. According to this configuration, since there is no portion where stress is likely to concentrate on the covering material 16, cracks in the covering material 16 are suppressed, and the effect of suppressing strain and stress near the boundary between the active region 13 and the inactive region 14 is achieved. It can be maintained for a long time.
  • the thickness of the covering material 16 is thinner on the end side of the first side surface 151 than in the vicinity of the boundary between the active region 13 and the inactive region 14 when viewed from the stacking direction of the stacked body 10. It can be set as the structure which has.
  • the thickness of the covering material 16 gradually decreases from the vicinity of the boundary between the active region 13 and the inactive region 14 to the end, and is thinner at the end than the central portion of the active region 13. It has become.
  • the covering material 16 can easily follow the expansion and contraction of the laminated body 10 at the end side portion of the first side surface 151, so that the covering material 16 is peeled off from the end of the first side surface 151. It is suppressed. Therefore, the effect of suppressing strain and stress near the boundary between the active region 13 and the inactive region 14 can be maintained for a long time.
  • the stacked body 10 has a quadrangular prism shape, and has a pair of first side surfaces 151 and second side surfaces 152, that is, the first internal electrode layer 121 and the first side surfaces.
  • 2 has a pair of first side faces 151 that both end faces of the internal electrode layer 122 reach, and one of the end faces of the first internal electrode layer 121 and the second internal electrode layer 122 is It is the structure which has a pair of the 2nd side surface 152 which has reached.
  • the covering material 16 is provided on the pair of first side surfaces 151 in the stacked body 10, but the covering material 16 is provided only on the pair of first side surfaces 151.
  • the configuration is not limited, and a configuration in which the covering material 16 is also provided on the pair of second side surfaces 152 may be used. That is, a configuration in which the covering material 16 is provided over the entire circumference of the side surface of the laminate 10 may be employed.
  • the covering material 16 covers all of the pair of first side surfaces 151 and the pair of second side surfaces 152, and the pair of first side surfaces as viewed from the stacking direction. 151 and the pair of second side surfaces 152 can be configured such that the thickness changes of the covering material 16 are changed in the same shape.
  • the example illustrated in FIG. 7 illustrates an example in which the covering material 16 having the shape illustrated in FIG. 4 is provided on all the side surfaces of the pair of first side surfaces 151 and the pair of second side surfaces 152.
  • 8 shows an example in which the covering material 16 having the shape shown in FIG. 6 is provided on all the side surfaces of the pair of first side surfaces 151 and the pair of second side surfaces 152.
  • any one of the first side surface 151 reached by both end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122, the first internal electrode layer 121, and the second internal electrode layer 122 is described.
  • the multilayer piezoelectric element 1 in which all of the four side surfaces of the quadrangular columnar stacked body 10 are the first side surfaces 151 may be used. That is, as in the examples shown in FIGS. 9 to 11, both end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 reach all four side surfaces of the quadrangular columnar laminate 10. Also good. That is, in this example, the second side surface 152 that reaches one of the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 is not provided.
  • the shape of the first internal electrode layer 121 viewed from the stacking direction is a shape that is the same size as the piezoelectric layer 11 and has one corner of the same square cut out (corner cut).
  • the shape of the second internal electrode layer 122 is a shape (point-symmetric shape) obtained by rotating the first internal electrode layer 121 180 degrees around the center viewed from the stacking direction.
  • the cut-out portion of the first internal electrode layer 121 and the cut-out portion of the second internal electrode layer 122 are positioned at diagonal corners of the quadrangle. With such a shape, the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 reach all four side surfaces of the quadrangular columnar laminate 10, and all four side surfaces are the first side surfaces. 151.
  • the inactive region 14 is formed on the end surface of the first internal electrode layer 121 or the second internal electrode layer 122 by cutting off either the first internal electrode layer 121 or the second internal electrode layer 122. Part is the part that has not reached the side.
  • the external electrode 17 is provided on the inactive region 14 of the pair of opposing side surfaces (first side surface 151) having the relatively wide inactive region 14 when viewed from the stacking direction.
  • the end face of the first internal electrode layer 121 or the end face of the second internal electrode layer 122 reaching the inactive region 13 is electrically connected to the external electrode 17.
  • the thickness of the covering material 16 is thicker in the vicinity of the boundary between the active region 13 and the inactive region 14 than the central portion of the active region 13.
  • the central portion of the active region 13 referred to here is the central portion of the active region 13 in the first side surface 151 when viewed from the stacking direction (the central portion of the active region 13 facing the first side surface 151), In other words, it means the central portion of the portion of the first side surface 151 where the first internal electrode layer 121 and the second internal electrode layer 122 have reached.
  • the thickness of the covering material 16 may change gently as viewed from the stacking direction, or the covering material 16 may be changed as viewed from the stacking direction.
  • the thickness may be thinner on the end side of the first side surface 151 (the end of the covering material 16) than the vicinity of the boundary between the active region 13 and the inactive region 14.
  • a ceramic green sheet to be the piezoelectric layer 11 is produced.
  • a ceramic slurry is prepared by mixing a calcined powder of piezoelectric ceramic, a binder made of an organic polymer such as acrylic or butyral, and a plasticizer. And a ceramic green sheet is produced using this ceramic slurry by using tape molding methods, such as a doctor blade method and a calender roll method.
  • the piezoelectric ceramic any material having piezoelectric characteristics may be used.
  • a perovskite oxide made of lead zirconate titanate (PbZrO 3 -PbTiO 3 ) can be used.
  • the plasticizer dibutyl phthalate (DBP), dioctyl phthalate (DOP), or the like can be used.
  • a conductive paste to be the first internal electrode layer 121 and the second internal electrode layer 122 is produced.
  • a conductive paste is prepared by adding and mixing a binder and a plasticizer to a metal powder of a silver-palladium alloy. This conductive paste is applied on the ceramic green sheet in a pattern of the first internal electrode layer 121 and the second internal electrode layer 122 by using a screen printing method. Further, a plurality of ceramic green sheets on which this conductive paste is printed are stacked, debindered at a predetermined temperature, and then fired at a temperature of 900 to 1200 ° C.
  • the piezoelectric layer 11, the first internal electrode layer 121, and the second internal electrode layer 122 are alternately stacked by performing a grinding process so as to have a predetermined shape using a surface grinder or the like.
  • An active part is produced.
  • the inactive portion is produced by laminating ceramic green sheets to which the conductive paste to be the first internal electrode layer 121 and the second internal electrode layer 122 is not applied.
  • the laminated body 10 is manufactured by combining an active part and an inactive part.
  • the laminated body 10 is not limited to the one produced by the above manufacturing method, and is formed by laminating a plurality of piezoelectric layers 11, first internal electrode layers 121, and second internal electrode layers 122. As long as the laminated body 10 can be produced, it may be produced by any manufacturing method.
  • the external electrode 17 is formed. Specifically, a conductive paste containing a metal such as silver or copper is used. This is baked on a region (second side surface 152) from which one end surface of the first internal electrode layer 121 and the second internal electrode layer 122 on the side surface of the multilayer body 10 is derived, for example, 5 ⁇ m to 70 ⁇ m. A thick external electrode 17 is formed. It can be formed by controlling to a predetermined thickness or width by screen printing or dispensing. For example, a silver glass-containing conductive paste prepared by adding a binder, a plasticizer, and a solvent to a mixture of conductive particles mainly containing silver and glass is used. Then, after printing on the side surface of the laminate 10 with a pattern of the external electrode 17 by a screen printing method and drying, a baking process is performed at a temperature of 650 to 750 ° C.
  • the covering material 16 is formed.
  • a resin such as epoxy, silicone, or nylon can be used, and at least the first side surface 151 can be formed with a predetermined thickness controlled by printing or dispensing.
  • the multilayer piezoelectric element 1 includes a covering material 16 that covers at least the first side surface 151 of the multilayer body 10, and covers the first side surface 151 when viewed from the stacking direction of the multilayer body 10.
  • the amount of application of the portion where the thickness is to be increased by the dispenser increases.
  • coating controlling.
  • it can be produced by overcoating the portion where the thickness is desired to be increased.
  • covering material 16 changes gently seeing from the lamination direction it can produce by insert-molding using the metal mold
  • a multilayer electric element 1 is completed by applying a direct current electric field of 0.1 to 3 kV / mm to the external electrode 17 to polarize the piezoelectric layer 11 constituting the multilayer body 10.
  • This multilayer piezoelectric element 1 is connected to an external power source via an external electrode 17 and applies a voltage to the piezoelectric layer 11, whereby each piezoelectric layer 11 can be greatly displaced by the inverse piezoelectric effect. .
  • 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 illustrating an example of the injection device of the present embodiment.
  • the multilayer piezoelectric element 1 of the above example is accommodated in a storage container (container) 23 having an injection hole 21 at one end.
  • a needle valve 25 capable of opening and closing the injection hole 21 is disposed.
  • a fluid passage 27 is disposed in the injection hole 21 so as to be able to communicate with the movement of the needle valve 25.
  • the fluid passage 27 is connected to an external fluid supply source, and fluid is constantly supplied to the fluid passage 27 at a high pressure. Therefore, when the needle valve 25 opens the injection hole 21, the fluid supplied to the fluid passage 27 is discharged from the injection hole 21 to the outside or an adjacent container, for example, a fuel chamber (not shown) of the internal combustion engine. It is configured.
  • the upper end portion of the needle valve 25 has a large inner diameter, and is a piston 31 slidable with a cylinder 29 formed in the storage container 23.
  • the multilayer piezoelectric element 1 of the above-described example is stored in contact with the piston 31.
  • the injection hole 21 is opened and closed by driving the multilayer piezoelectric element 1. Specifically, when the multilayer piezoelectric element 1 is extended by applying a voltage, the piston 31 is pressed, the needle valve 25 closes the fluid passage 27 leading to the injection hole 21, and the supply of fluid is stopped. When the voltage application is stopped, the laminated piezoelectric element 1 contracts, the disc spring 33 pushes back the piston 31, the fluid passage 27 is opened, and the injection hole 21 communicates with the fluid passage 27. Fluid injection is performed.
  • the fluid passage 27 may be opened by applying a voltage to the multilayer piezoelectric element 1 and the fluid passage 27 may be closed by stopping the application of the voltage.
  • the multilayer piezoelectric element 1 does not necessarily have to be inside the storage container 23, and is configured such that a pressure for controlling the ejection of fluid is applied to the interior of the storage container 23 by driving the multilayer piezoelectric element 1.
  • the fluid includes various liquids and gases such as conductive paste in addition to fuel, ink, and the like.
  • the injection device 19 of the present example employing the multilayer piezoelectric element 1 of the above example is used for an internal combustion engine, the fuel is accurately injected into the combustion chamber of the internal combustion engine such as an engine over a longer period of time compared to the conventional injection device. Can be made.
  • FIG. 13 is a schematic diagram illustrating an example of the fuel injection system of the present embodiment.
  • the fuel injection system 35 of this example includes a common rail 37 that stores high-pressure fuel as a high-pressure fluid, and a plurality of injection devices 19 of the above-described examples that inject the high-pressure fluid stored in the common rail 37.
  • a pressure pump 39 for supplying a high-pressure fluid to the common rail 37 and an injection control unit 41 for supplying a drive signal to the injection device 19 are provided.
  • the injection control unit 41 controls the amount and timing of high-pressure fluid injection based on external information or an external signal. For example, if the fuel injection system 35 of this example is used for engine fuel injection, the amount and timing of fuel injection can be controlled while sensing the state of the combustion chamber of the engine with a sensor or the like.
  • the pressure pump 39 serves to supply fluid fuel from the fuel tank 43 to the common rail 37 at a high pressure. For example, in the case of the fuel injection system 35 of the engine, the fluid fuel is fed into the common rail 37 at a high pressure of 1000 to 2000 atmospheres (about 101 MPa to about 203 MPa), preferably 1500 to 1700 atmospheres (about 152 MPa to about 172 MPa).
  • the high-pressure fuel sent from the pressure pump 39 is stored and sent to the injection device 19 as appropriate.
  • the ejection device 19 ejects a certain fluid from the ejection holes 21 to the outside or an adjacent container.
  • the target for injecting and supplying fuel is an engine
  • high-pressure fuel is injected from the injection hole 21 into the combustion chamber of the engine in the form of a mist.
  • desired injection of high-pressure fuel can be stably performed over a long period of time.
  • a piezoelectric actuator provided with a multilayer piezoelectric element was produced as follows. First, a ceramic slurry was prepared by mixing a calcined powder of a piezoelectric ceramic mainly composed of lead zirconate titanate (PbZrO 3 —PbTiO 3 ) having an average particle size of 0.4 ⁇ m, a binder, and a plasticizer. Using this ceramic slurry, a ceramic green sheet serving as a piezoelectric layer having a thickness of 50 ⁇ m was prepared by a doctor blade method.
  • a ceramic slurry was prepared by mixing a calcined powder of a piezoelectric ceramic mainly composed of lead zirconate titanate (PbZrO 3 —PbTiO 3 ) having an average particle size of 0.4 ⁇ m, a binder, and a plasticizer.
  • a ceramic green sheet serving as a piezoelectric layer having a thickness of 50 ⁇ m was prepared by a doctor blade method.
  • a binder was added to the silver-palladium alloy to produce a conductive paste to be an internal electrode layer.
  • a conductive paste serving as the first and second internal electrode layers was printed by a screen printing method, and 200 ceramic green sheets on which the conductive paste was printed were laminated.
  • the ceramic green sheets on which the conductive paste serving as the internal electrode layer is not printed above and below the 200 ceramic green sheets printed with the conductive paste serving as the first and second internal electrode layers A total of 15 sheets were laminated. Then, it was fired at 980 to 1100 ° C. and ground to a predetermined shape using a surface grinder to obtain a laminate having an end face of 5 mm square.
  • a conductive paste in which a binder of silver and glass was mixed was printed on the side surface of the laminate by screen printing, and baked at 700 ° C. to form external electrodes.
  • a bonding material in the form of a mixed paste of silver powder and polyimide resin was applied to the surface of the external electrode with a dispenser, and the external electrode plate was attached in parallel with the side surface of the laminate.
  • Example 1 a coating material having a uniform thickness of 50 ⁇ m was prepared (Sample 1).
  • a relatively thick portion facing the vicinity of the boundary between the active region and the inactive region has a protrusion (ridge portion) extending in the stacking direction having a rectangular cross section.
  • a silicone resin coating material was prepared (Sample 2).
  • the thickness of the thin portion was 50 ⁇ m
  • the thickness of the thick portion was 100 ⁇ m.
  • a relatively thick portion facing the vicinity of the boundary between the active region and the inactive region has a protrusion (ridge portion) extending in the stacking direction having a rectangular cross section
  • a sample in which a coating material made of silicone resin whose thickness changes gently was prepared (Sample 3).
  • the thick and thin connection portions are gently connected at an angle of 45 °.
  • the thin part was 50 ⁇ m
  • the thick part (projection height) was 100 ⁇ m.
  • the protrusion has a shape that rises so that the width becomes narrow at an angle of about 45 °, and the boundary between the protrusion and the other area is rounded and has a gentle shape. It was.
  • a polarization process was performed by applying a DC electric field of 3 kV / mm to the laminated piezoelectric elements of Samples 1 to 3 through a lead member welded to an external electrode for 15 minutes.
  • a DC voltage of 160 V was applied to these stacked piezoelectric elements, a displacement of 30 ⁇ m was obtained in the stacking direction of the stacked body.
  • these laminated piezoelectric elements were continuously driven 50 times in a test environment at a temperature of 25 ° C. and a humidity of 60% with a sine waveform with a frequency of 150 Hz for 1 hour and stopped for 1 hour.
  • the multilayer piezoelectric element of the example has excellent long-term reliability.

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Abstract

A stacked piezoelectric element 1 according to the present disclosure comprises an active region 13 where a first internal electrode layer 121 and a second internal electrode layer 122 overlap each other when viewed from the stacking direction and an inert region 14 where the first internal electrode layer 121 and the second internal electrode layer 122 do not overlap each other when viewed from the stacking direction. This stacked piezoelectric element 1 also comprises a first lateral surface 151 with which end faces of both the first internal electrode layer 121 and the second internal electrode layer 122 come into contact. This stacked piezoelectric element 1 is additionally provided with a cover material 16 that covers at least the first lateral surface 151 of a stack 10; and the thickness of the cover material 16 covering the first lateral surface 151 around the boundary between the active region 13 and the inert region 14 is thicker than the thickness thereof in the central part of the active region 13 when viewed from the stacking direction.

Description

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Multilayer piezoelectric element, injection device including the same, and fuel injection system
　本開示は、圧電駆動素子（圧電アクチュエータ），圧力センサ素子および圧電回路素子等として用いられる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に関する。 The present disclosure relates to a laminated piezoelectric element used as a piezoelectric driving element (piezoelectric actuator), a pressure sensor element, a piezoelectric circuit element, and the like, an injection apparatus including the same, and a fuel injection system.
　積層型圧電素子として、第１の内部電極層および第２の内部電極層が圧電体層を介して交互に積層された積層体と、積層体の側面に設けられた被覆材を有しているものが知られている。そして、積層型圧電素子として、積層方向から見て第１の内部電極層と第２の内部電極層とが重なる活性領域と、積層方向から見て第１の内部電極層と第２の内部電極層とが重ならない不活性領域とを有しているものが知られている（例えば特許文献１を参照）。 The laminated piezoelectric element has a laminate in which the first internal electrode layers and the second internal electrode layers are alternately laminated via the piezoelectric layers, and a covering material provided on the side surface of the laminate. Things are known. The stacked piezoelectric element includes an active region in which the first internal electrode layer and the second internal electrode layer overlap each other when viewed from the stacking direction, and the first internal electrode layer and the second internal electrode when viewed from the stacking direction. One having an inactive region that does not overlap with a layer is known (see, for example, Patent Document 1).
特開平７－７１９３号公報Japanese Patent Laid-Open No. 7-7193
　本開示の積層型圧電素子は、第１の内部電極層および第２の内部電極層が圧電体層を介して交互に積層されてなる積層体を備えている。積層体は、積層方向から見て前記第１の内部電極層と前記第２の内部電極層とが重なる活性領域と、積層方向から見て前記第１の内部電極層と前記第２の内部電極層とが重ならない不活性領域とを有している。また、積層体は、前記第１の内部電極層および前記第２の内部電極層の両方の端面が達する第１の側面を有している。そして、積層型圧電素子は、積層体の少なくとも前記第１の側面を被覆する被覆材を備えていて、積層方向から見て、前記第１の側面を被覆する前記被覆材の厚みが、前記活性領域の中央部よりも前記活性領域と前記不活性領域との境界付近で厚くなっている。 The multilayer piezoelectric element of the present disclosure includes a multilayer body in which first internal electrode layers and second internal electrode layers are alternately stacked via piezoelectric layers. The stacked body includes an active region in which the first internal electrode layer and the second internal electrode layer overlap each other when viewed from the stacking direction, and the first internal electrode layer and the second internal electrode when viewed from the stacking direction. And an inactive region that does not overlap the layer. In addition, the multilayer body has a first side surface to which both end faces of the first internal electrode layer and the second internal electrode layer reach. The multilayer piezoelectric element includes a coating material that covers at least the first side surface of the multilayer body, and the thickness of the coating material that covers the first side surface when viewed from the stacking direction is the active material. It is thicker in the vicinity of the boundary between the active region and the inactive region than the central portion of the region.
　また、本開示の噴射装置は、噴射孔を有する容器と、上記の積層型圧電素子とを備え、該積層型圧電素子の駆動によって前記噴射孔が開閉されるものである。 Also, the injection device of the present disclosure includes a container having an injection hole and the multilayer piezoelectric element described above, and the injection hole is opened and closed by driving the multilayer piezoelectric element.
　また、本開示の燃料噴射システムは、高圧燃料を蓄えるコモンレールと、該コモンレールに蓄えられた前記高圧燃料を噴射する上記の噴射装置と、前記コモンレールに前記高圧燃料を供給する圧力ポンプと、前記噴射装置に駆動信号を与える噴射制御ユニットとを備える。 The fuel injection system of the present disclosure includes a common rail that stores high-pressure fuel, the above-described injection device 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 An injection control unit for supplying a drive signal to the apparatus.
積層型圧電素子の一例の斜視図である。It is a perspective view of an example of a lamination type piezoelectric element. 図１に示す積層型圧電素子の分解図である。FIG. 2 is an exploded view of the multilayer piezoelectric element shown in FIG. 1. 図１に示す積層型圧電素子の平面図である。FIG. 2 is a plan view of the multilayer piezoelectric element shown in FIG. 1. 積層型圧電素子の他の例の平面図である。It is a top view of other examples of a lamination type piezoelectric element. 積層型圧電素子の他の例の平面図である。It is a top view of other examples of a lamination type piezoelectric element. 積層型圧電素子の他の例の平面図である。It is a top view of other examples of a lamination type piezoelectric element. 積層型圧電素子の他の例の平面図である。It is a top view of other examples of a lamination type piezoelectric element. 積層型圧電素子の他の例の平面図である。It is a top view of other examples of a lamination type piezoelectric element. 積層型圧電素子の他の例の斜視図である。It is a perspective view of the other example of a lamination type piezoelectric element. 図９に示す積層型圧電素子の分解図である。FIG. 10 is an exploded view of the multilayer piezoelectric element shown in FIG. 9. 図９に示す積層型圧電素子の平面図である。FIG. 10 is a plan view of the multilayer piezoelectric element shown in FIG. 9. 噴射装置の実施形態の一例を示す概略的な断面図である。It is a schematic sectional drawing showing an example of an embodiment of an injection device. 燃料噴射システムの実施形態の一例を示す概略的なブロック図である。1 is a schematic block diagram illustrating an example of an embodiment of a fuel injection system.
　従来の積層型圧電素子においては、活性領域と不活性領域との境界は応力が集中することから、この境界に位置する積層体の表面にはクラックが生じやすくなっている。このように、積層体にクラックが生じると、絶縁破壊を起こすおそれがあり、積層型圧電素子の長期信頼性が低下してしまう。 In the conventional multilayer piezoelectric element, stress concentrates at the boundary between the active region and the inactive region, so that the surface of the multilayer body located at this boundary is likely to crack. Thus, when a crack arises in a laminated body, there exists a possibility of causing a dielectric breakdown, and the long-term reliability of a laminated piezoelectric element will fall.
　本開示は上記事情に鑑みてなされたもので、積層体の絶縁破壊を抑制し、長期信頼性に優れた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を提供することを目的とする。 The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a multilayer piezoelectric element that suppresses dielectric breakdown of a multilayer body and has excellent long-term reliability, an injection device including the multilayer piezoelectric element, and a fuel injection system. To do.
　以下、本実施形態の積層型圧電素子の一例について図面を参照して説明する。 Hereinafter, an example of the multilayer piezoelectric element of the present embodiment will be described with reference to the drawings.
　図１は積層型圧電素子の実施形態の一例を示す斜視図、図２は図１に示す積層型圧電素子の分解図、図３は図１に示す積層型圧電素子の平面図である。 1 is a perspective view showing an example of an embodiment of a multilayer piezoelectric element, FIG. 2 is an exploded view of the multilayer piezoelectric element shown in FIG. 1, and FIG. 3 is a plan view of the multilayer piezoelectric element shown in FIG.
　図１乃至図３に示す積層型圧電素子１は、第１の内部電極層１２１および第２の内部電極層１２２が圧電体層１１を介して交互に積層されてなる積層体１０を備えている。積層体１０は、積層方向から見て第１の内部電極層１２１と第２の内部電極層１２２とが重なる活性領域１３と、積層方向から見て第１の内部電極層１２１と第２の内部電極層１２２とが重ならない不活性領域１４とを有している。また、積層体１０は、第１の内部電極層１２１および第２の内部電極層１２２の両方の端面が達する第１の側面１５１を有している。そして、積層型圧電素子１は、積層体１０の少なくとも第１の側面１５１を被覆する被覆材１６を備えていて、積層方向から見て、第１の側面１５１を被覆する被覆材１６の厚みが、活性領域１３の中央部よりも活性領域１３と不活性領域１４との境界付近で厚くなっている。 The multilayer piezoelectric element 1 shown in FIGS. 1 to 3 includes a multilayer body 10 in which first internal electrode layers 121 and second internal electrode layers 122 are alternately stacked with piezoelectric layers 11 interposed therebetween. . The stacked body 10 includes an active region 13 where the first internal electrode layer 121 and the second internal electrode layer 122 overlap as viewed from the stacking direction, and the first internal electrode layer 121 and the second internal electrode viewed from the stacking direction. The inactive region 14 that does not overlap the electrode layer 122 is provided. In addition, the stacked body 10 has a first side surface 151 that reaches both end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122. The multilayer piezoelectric element 1 includes the covering material 16 that covers at least the first side surface 151 of the multilayer body 10, and the thickness of the covering material 16 that covers the first side surface 151 is viewed from the stacking direction. The thickness is thicker in the vicinity of the boundary between the active region 13 and the inactive region 14 than the central portion of the active region 13.
　積層型圧電素子１を構成する積層体１０は、第１の内部電極層１２１および第２の内部電極層１２２が圧電体層１１を介して交互に積層されたものである。この積層体１０は、積層方向から見て第１の内部電極層１２１と第２の内部電極層１２２とが重なる活性領域１３と、積層方向から見て第１の内部電極層１２１と第２の内部電極層１２２とが重ならない不活性領域１４とを有している。ここで、活性領域１３は駆動時に積層方向に伸長または収縮する部位である。また、不活性領域１４は駆動時に積層方向に伸長または収縮しないかまたはしにくい部位である。 The laminated body 10 constituting the laminated piezoelectric element 1 is obtained by alternately laminating first internal electrode layers 121 and second internal electrode layers 122 with the piezoelectric layers 11 interposed therebetween. The stacked body 10 includes an active region 13 where the first internal electrode layer 121 and the second internal electrode layer 122 overlap each other when viewed from the stacking direction, and the first internal electrode layer 121 and the second internal electrode layer viewed from the stacking direction. The inactive region 14 does not overlap with the internal electrode layer 122. Here, the active region 13 is a portion that expands or contracts in the stacking direction during driving. Further, the inactive region 14 is a portion that does not stretch or shrink in the stacking direction during driving or is difficult to do.
　なお、積層体１０は、第１の内部電極層１２１および第２の内部電極層１２２が圧電体層１１を介して交互に積層された部分と、積層方向両端部に設けられた圧電体層１１のみが積層された部分とを有している。この積層方向両端部に位置する圧電体層１１のみが積層された部分も、駆動時に積層方向に伸長または収縮しない部位である。 The laminated body 10 includes a portion where the first internal electrode layers 121 and the second internal electrode layers 122 are alternately laminated via the piezoelectric layers 11 and the piezoelectric layers 11 provided at both ends in the lamination direction. Only the laminated part. The portions where only the piezoelectric layers 11 positioned at both ends in the stacking direction are stacked are also portions that do not expand or contract in the stacking direction during driving.
　この積層体１０は、例えば縦０．５ｍｍ～１０ｍｍ、横０．５ｍｍ～１０ｍｍ、高さ１ｍｍ～１００ｍｍの四角柱状（直方体状）にされている。積層体１０としては、六角柱形状や八角柱形状、円柱状などであってもよい。 The laminated body 10 has, for example, a rectangular column shape (a rectangular parallelepiped shape) having a length of 0.5 mm to 10 mm, a width of 0.5 mm to 10 mm, and a height of 1 mm to 100 mm. The laminated body 10 may have a hexagonal prism shape, an octagonal prism shape, a cylindrical shape, or the like.
　積層体１０を構成する圧電体層１１は、圧電特性を有するセラミックスからなるものである。このようなセラミックスとして、例えばチタン酸ジルコン酸鉛（ＰｂＺｒＯ３－ＰｂＴｉＯ３）からなるペロブスカイト型酸化物、ニオブ酸リチウム（ＬｉＮｂＯ３）、タンタル酸リチウム（ＬｉＴａＯ３）などを用いることができる。この圧電体層１１の厚みは、例えば３μｍ～２５０μｍとされる。 The piezoelectric layer 11 constituting the laminate 10 is made of ceramics having piezoelectric characteristics. As such a ceramic, for example, a perovskite oxide made of lead zirconate titanate (PbZrO 3 —PbTiO 3 ), lithium niobate (LiNbO 3 ), lithium tantalate (LiTaO 3 ), or the like can be used. The thickness of the piezoelectric layer 11 is, for example, 3 μm to 250 μm.
　積層体１０を構成する第１の内部電極層１２１および第２の内部電極層１２２は、圧電体層１１を形成するセラミックスと同時焼成により形成されたものである。第１の内部電極層１２１および第２の内部電極層１２２は、圧電体層１１と交互に積層されて圧電体層１１を上下から挟んでいる。例えば正極を第１の内部電極層１２１、負極を第２の内部電極層１２２として積層体１０に交互に配置されることにより、それらの間に挟まれた圧電体層１１に駆動電圧が印加される。この材料として、例えば銀－パラジウム合金を主成分とする導体、あるいは銅、白金などを含む導体を用いることができる。図に示す例では、第１の内部電極層１２１および第２の内部電極層１２２がそれぞれ積層体１０の対向する一対の側面に互い違いに引き出されて、後述する積層体１０の側面に設けられた一対の外部電極１７と電気的に接続されている。第１の内部電極層１２１および第２の内部電極層１２２の厚みは、例えば０．１μｍ～５μｍとされる。 The first internal electrode layer 121 and the second internal electrode layer 122 constituting the laminated body 10 are formed by simultaneous firing with the ceramic forming the piezoelectric layer 11. The first internal electrode layers 121 and the second internal electrode layers 122 are alternately stacked with the piezoelectric layers 11 to sandwich the piezoelectric layers 11 from above and below. For example, by alternately arranging the positive electrode as the first internal electrode layer 121 and the negative electrode as the second internal electrode layer 122 in the stacked body 10, a driving voltage is applied to the piezoelectric layer 11 sandwiched therebetween. The As this material, for example, a conductor mainly composed of a silver-palladium alloy or a conductor containing copper, platinum, or the like can be used. In the example shown in the figure, the first internal electrode layer 121 and the second internal electrode layer 122 are alternately drawn out to a pair of opposing side surfaces of the stacked body 10 and provided on the side surfaces of the stacked body 10 described later. A pair of external electrodes 17 are electrically connected. The thickness of the first internal electrode layer 121 and the second internal electrode layer 122 is, for example, 0.1 μm to 5 μm.
　ここで、第１の内部電極層１２１および第２の内部電極層１２２のいずれか一方の端面が達する側面（第２の側面１５２）は、第１の内部電極層１２１および第２の内部電極層１２２がそれぞれ互い違いに引き出された積層体１０の対向する一対の側面である。 Here, the side surface (second side surface 152) reached by either one of the first internal electrode layer 121 and the second internal electrode layer 122 is the first internal electrode layer 121 and the second internal electrode layer. Reference numerals 122 denote a pair of opposing side surfaces of the stacked body 10 drawn alternately.
　また、積層体１０の第２の側面１５２（対向する一対の側面）以外の他の対向する一対の側面は第１の側面１５１であり、この第１の側面に第１の内部電極層１２１および第２の内部電極層１２２の両方の端面が達している。 A pair of opposing side surfaces other than the second side surface 152 (a pair of opposing side surfaces) of the stacked body 10 is a first side surface 151, and the first internal electrode layer 121 and the first side surface 151 are provided on the first side surface. Both end faces of the second internal electrode layer 122 reach.
　なお、積層体１０には、応力を緩和するための層であって内部電極層として機能しない金属層等が含まれていてもよい。 In addition, the laminated body 10 may include a metal layer that is a layer for relaxing stress and does not function as an internal electrode layer.
　そして、第１の内部電極層１２１および第２の内部電極層１２２のいずれか一方の端面が達する第２の側面１５２にはそれぞれ外部電極１７が設けられ、引き出された第１の内部電極層１２１または第２の内部電極層１２２と電気的に接続されている。この外部電極１７は、例えば銀や銅などの金属を含んだ導電性ペーストを焼き付けて作製することができる。ここで、外部電極１７を積層体１０の側面に垂直な横断面で見たときに、外部電極１７の厚みは５μｍ～７０μｍの厚さにされる。図示しないが、外部電極１７の端部にリード部材が接合され、リード部材を介して外部回路との電気的な接続がなされる。 Then, external electrodes 17 are provided on the second side surfaces 152 that reach one of the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122, respectively, and the first internal electrode layer 121 drawn out is provided. Alternatively, it is electrically connected to the second internal electrode layer 122. The external electrode 17 can be produced by baking a conductive paste containing a metal such as silver or copper. Here, when the external electrode 17 is viewed in a cross section perpendicular to the side surface of the multilayer body 10, the thickness of the external electrode 17 is set to 5 μm to 70 μm. Although not shown, a lead member is joined to the end of the external electrode 17, and electrical connection with an external circuit is made through the lead member.
　そして、積層型圧電素子１は、積層体１０の少なくとも第１の側面１５１を被覆する被覆材１６を備えている。この被覆材１６の厚みは、積層体１０の積層方向から見て、活性領域１３の中央部よりも活性領域１３と不活性領域１４との境界付近で厚くなっている。 The multilayer piezoelectric element 1 includes a covering material 16 that covers at least the first side surface 151 of the multilayer body 10. The thickness of the covering material 16 is larger in the vicinity of the boundary between the active region 13 and the inactive region 14 than in the central portion of the active region 13 when viewed from the stacking direction of the stacked body 10.
　なお、積層体１０の積層方向から見た場合の活性領域１３の中央部は、厳密には積層体１０の内部に位置しているものの、ここでいう積層方向から見た場合の活性領域１３の中央部とは、積層方向から見た場合の第１の側面１５１に面した活性領域１３の中央部、言い換えれば、第１の側面１５１における第１の内部電極層１２１および第２の内部電極層１２２が達している部分の中央部のことを意味している。図１～図３に示す例においては、第１の内部電極層１２１および第２の内部電極層１２２は、それぞれ反対側の第２の側面１５２から互い違いに積層体１０の内部へ向かって延びる長さが同じであって、第１の側面１５１で見て左右対称（線対称）になっている。したがって、積層方向から見た場合の活性領域１３の中央部は、第１の側面１５１の中央に位置している。 In addition, although the central part of the active region 13 when viewed from the stacking direction of the stacked body 10 is strictly located inside the stacked body 10, the active region 13 when viewed from the stacking direction referred to here. The central portion is the central portion of the active region 13 facing the first side surface 151 when viewed from the stacking direction, in other words, the first internal electrode layer 121 and the second internal electrode layer on the first side surface 151. It means the central part of the part where 122 reaches. In the example shown in FIGS. 1 to 3, the first internal electrode layer 121 and the second internal electrode layer 122 are extended from the opposite second side surfaces 152 alternately toward the inside of the stacked body 10. Are the same, and are symmetric (line symmetric) when viewed from the first side 151. Therefore, the central portion of the active region 13 when viewed from the stacking direction is located at the center of the first side surface 151.
　また、被覆材１６における活性領域１３と不活性領域１４との境界付近とは、被覆材１６が設けられた側面における活性領域１３と不活性領域１４との境界に対向する部位およびその近傍領域のことを意味している。具体的には、積層体１０を平面視したときに、被覆材１６が設けられた側面における活性領域１３と不活性領域１４との境界から当該側面の長さ（幅）の１／１０以内の範囲を、活性領域１３と不活性領域１４との境界付近とする。 In addition, the vicinity of the boundary between the active region 13 and the inactive region 14 in the covering material 16 is a portion of the side surface on which the covering material 16 is provided that faces the boundary between the active region 13 and the inactive region 14 and its vicinity region. It means that. Specifically, when the laminate 10 is viewed in plan, it is within 1/10 of the length (width) of the side surface from the boundary between the active region 13 and the inactive region 14 on the side surface on which the covering material 16 is provided. The range is set near the boundary between the active region 13 and the inactive region 14.
　被覆材１６は、例えばシリコーン樹脂、エポキシ樹脂、ナイロン樹脂などからなり、単層のみならず、複数層で構成されていてもよい。この被覆材１６は、第１の内部電極層１２１および第２の内部電極層１２２の両方の端面が達する積層体１０の第１の側面１５１におけるマイグレーションや放電を抑制する効果を奏する。図１～図３に示す例では、この被覆材１６は、第１の側面１５１のみにおいて第１の内部電極層１２１および第２の内部電極層１２２の端面を覆って露出させないように設けられている。 The covering material 16 is made of, for example, a silicone resin, an epoxy resin, a nylon resin, or the like, and may be composed of not only a single layer but also a plurality of layers. The covering material 16 has an effect of suppressing migration and discharge on the first side surface 151 of the stacked body 10 that both end faces of the first internal electrode layer 121 and the second internal electrode layer 122 reach. In the example shown in FIGS. 1 to 3, the covering material 16 is provided so as not to cover and expose the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 only on the first side surface 151. Yes.
　ここで、活性領域１３と不活性領域１４との境界は応力が集中することから、この境界に位置する積層体１０の表面（第１の側面１５１）にはクラックが生じやすくなっている。これに対し、本例の積層型圧電素子１は、駆動による伸縮によく追従する活性領域１３の中央部では被覆材１６の厚みが薄く、応力が集中する活性領域１３と不活性領域１４との境界付近では被覆材１６の厚みが厚くなっている。これにより、活性領域１３と不活性領域１４の間に生じる歪を小さくでき、応力を低減することができる。したがって、積層体１０にクラックが生じるのを抑制し、絶縁破壊を抑制することができる。したがって、長期信頼性に優れた積層型圧電素子１とすることができる。 Here, since stress concentrates at the boundary between the active region 13 and the inactive region 14, cracks are likely to occur on the surface (first side surface 151) of the laminate 10 located at this boundary. On the other hand, in the laminated piezoelectric element 1 of the present example, the thickness of the covering material 16 is thin at the center of the active region 13 that well follows expansion and contraction by driving, and the active region 13 and the inactive region 14 where stress concentrates. In the vicinity of the boundary, the covering material 16 is thick. Thereby, the distortion which arises between the active region 13 and the inactive region 14 can be made small, and stress can be reduced. Therefore, it is possible to suppress the generation of cracks in the laminated body 10 and suppress dielectric breakdown. Therefore, the multilayer piezoelectric element 1 having excellent long-term reliability can be obtained.
　なお、被覆材１６の厚みとしては、活性領域１３の中央部に対向する相対的に薄い部位で例えば２０μｍ～４００μｍに設定され、活性領域１３と不活性領域１４との境界付近に対向する相対的に厚い部位で例えば薄い部位の厚みの１．１～５．０倍の厚みとされる。 The thickness of the covering material 16 is set to, for example, 20 μm to 400 μm at a relatively thin portion facing the central portion of the active region 13, and is relatively opposed to the vicinity of the boundary between the active region 13 and the inactive region 14. For example, the thickness is 1.1 to 5.0 times the thickness of the thin portion.
　また、図３に示す例では、活性領域１３と不活性領域１４との境界付近に対向する相対的に厚い部位は断面矩形状の積層方向に延びた突起（突条部）になっているが、このような突条部に限定されない。例えば図４に示すように、断面で見て先端に向かって幅が細くなるような断面形状の積層方向に延びた突起（突条部）であってもよい。 In the example shown in FIG. 3, the relatively thick portion facing the vicinity of the boundary between the active region 13 and the inactive region 14 is a protrusion (projection) extending in the stacking direction having a rectangular cross section. It is not limited to such a protrusion. For example, as shown in FIG. 4, it may be a protrusion (ridge portion) extending in the stacking direction in a cross-sectional shape such that the width becomes narrower toward the tip when viewed in cross section.
　ここで、図５に示すように、積層体１０の積層方向から見て、被覆材１６の厚みがなだらかに変化している構成とすることができる。この構成によれば、被覆材１６に応力が集中しやすい箇所がなくなるので、被覆材１６のクラックが抑制され、活性領域１３と不活性領域１４との境界付近の歪や応力を抑制する効果を長期間にわたって維持することができる。 Here, as shown in FIG. 5, the thickness of the covering material 16 can be changed gently when viewed from the stacking direction of the stacked body 10. According to this configuration, since there is no portion where stress is likely to concentrate on the covering material 16, cracks in the covering material 16 are suppressed, and the effect of suppressing strain and stress near the boundary between the active region 13 and the inactive region 14 is achieved. It can be maintained for a long time.
　また、図６に示すように、積層体１０の積層方向から見て、被覆材１６の厚みが活性領域１３と不活性領域１４との境界付近よりも第１の側面１５１の端側で薄くなっている構成とすることができる。ここで、図６に示す例では、被覆材１６の厚みが活性領域１３と不活性領域１４との境界付近から端にかけて徐々に薄くなって、最も端においては活性領域１３の中央部よりも薄くなっている。この構成によれば、被覆材１６が第１の側面１５１の端側の部位で積層体１０の伸縮に追従しやすくなっているので、被覆材１６の第１の側面１５１の端からの剥がれが抑制される。したがって、活性領域１３と不活性領域１４との境界付近の歪や応力を抑制する効果を長期間にわたって維持することができる。 Further, as shown in FIG. 6, the thickness of the covering material 16 is thinner on the end side of the first side surface 151 than in the vicinity of the boundary between the active region 13 and the inactive region 14 when viewed from the stacking direction of the stacked body 10. It can be set as the structure which has. Here, in the example shown in FIG. 6, the thickness of the covering material 16 gradually decreases from the vicinity of the boundary between the active region 13 and the inactive region 14 to the end, and is thinner at the end than the central portion of the active region 13. It has become. According to this configuration, the covering material 16 can easily follow the expansion and contraction of the laminated body 10 at the end side portion of the first side surface 151, so that the covering material 16 is peeled off from the end of the first side surface 151. It is suppressed. Therefore, the effect of suppressing strain and stress near the boundary between the active region 13 and the inactive region 14 can be maintained for a long time.
　また、本例は、積層体１０が四角柱状であって、第１の側面１５１および第２の側面１５２をそれぞれ一対ずつ有している構成、すわなち、第１の内部電極層１２１および第２の内部電極層１２２の両方の端面が達している第１の側面１５１を一対有しており、第１の内部電極層１２１および第２の内部電極層１２２のうちのいずれか一方の端面が達している第２の側面１５２を一対有している構成である。このような構成とすることで、第２の側面１５２には活性領域１３と不活性領域１４との境界が存在しないことから、歪や応力を生じる部分を少なくできる。 Further, in this example, the stacked body 10 has a quadrangular prism shape, and has a pair of first side surfaces 151 and second side surfaces 152, that is, the first internal electrode layer 121 and the first side surfaces. 2 has a pair of first side faces 151 that both end faces of the internal electrode layer 122 reach, and one of the end faces of the first internal electrode layer 121 and the second internal electrode layer 122 is It is the structure which has a pair of the 2nd side surface 152 which has reached. By adopting such a configuration, since the boundary between the active region 13 and the inactive region 14 does not exist on the second side surface 152, it is possible to reduce the portion where distortion or stress occurs.
　図１乃至図６に示す例では、被覆材１６は積層体１０における一対の第１の側面１５１に設けられているが、このような一対の第１の側面１５１のみに被覆材１６が設けられる構成に限られず、一対の第２の側面１５２にも被覆材１６が設けられた構成であってもよい。すなわち、積層体１０の側面の全周にわたって被覆材１６が設けられた構成であってもよい。 In the example shown in FIGS. 1 to 6, the covering material 16 is provided on the pair of first side surfaces 151 in the stacked body 10, but the covering material 16 is provided only on the pair of first side surfaces 151. The configuration is not limited, and a configuration in which the covering material 16 is also provided on the pair of second side surfaces 152 may be used. That is, a configuration in which the covering material 16 is provided over the entire circumference of the side surface of the laminate 10 may be employed.
　さらに、図７および図８に示すように、被覆材１６は一対の第１の側面１５１および一対の第２の側面１５２を全て被覆しており、積層方向から見て、一対の第１の側面１５１および一対の第２の側面１５２のそれぞれの被覆材１６の厚み変化が同じ形状で変化している構成とすることができる。ここで、図７に示す例は、図４に示す形状の被覆材１６を一対の第１の側面１５１および一対の第２の側面１５２の全ての側面に設けた例を示している。また、図８に示す例は、図６に示す形状の被覆材１６を一対の第１の側面１５１および一対の第２の側面１５２の全ての側面に設けた例を示している。 Further, as shown in FIGS. 7 and 8, the covering material 16 covers all of the pair of first side surfaces 151 and the pair of second side surfaces 152, and the pair of first side surfaces as viewed from the stacking direction. 151 and the pair of second side surfaces 152 can be configured such that the thickness changes of the covering material 16 are changed in the same shape. Here, the example illustrated in FIG. 7 illustrates an example in which the covering material 16 having the shape illustrated in FIG. 4 is provided on all the side surfaces of the pair of first side surfaces 151 and the pair of second side surfaces 152. 8 shows an example in which the covering material 16 having the shape shown in FIG. 6 is provided on all the side surfaces of the pair of first side surfaces 151 and the pair of second side surfaces 152.
　これにより、４面における被覆材１６の変位拘束力が均一に近づくことから、長期間にわたって安定した変位で駆動し続けることができる。 Thereby, since the displacement restraining force of the covering material 16 on the four surfaces approaches uniformly, the driving can be continued with a stable displacement over a long period of time.
　以上の説明は、第１の内部電極層１２１および第２の内部電極層１２２の両方の端面が達する第１の側面１５１と、第１の内部電極層１２１および第２の内部電極層１２２のいずれか一方の端面が達する第２の側面１５２とを有している積層体１０を備えた積層型圧電素子１の例である。 In the above description, any one of the first side surface 151 reached by both end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122, the first internal electrode layer 121, and the second internal electrode layer 122 is described. This is an example of the multilayer piezoelectric element 1 including the multilayer body 10 having the second side surface 152 reaching one of the end surfaces.
　この例に限らず、例えば、四角柱状の積層体１０の４つの側面の全てが第１の側面１５１である積層型圧電素子１でもよい。すなわち、図９～図１１に示す例のように、第１の内部電極層１２１および第２の内部電極層１２２の両方の端面が、四角柱状の積層体１０の４つの側面全てに達していてもよい。つまり、この例では、第１の内部電極層１２１および第２の内部電極層１２２のいずれか一方の端面が達する第２の側面１５２は備えていない。 For example, the multilayer piezoelectric element 1 in which all of the four side surfaces of the quadrangular columnar stacked body 10 are the first side surfaces 151 may be used. That is, as in the examples shown in FIGS. 9 to 11, both end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 reach all four side surfaces of the quadrangular columnar laminate 10. Also good. That is, in this example, the second side surface 152 that reaches one of the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 is not provided.
　この場合の第１の内部電極層１２１の積層方向から見た場合の形状は、圧電体層１１と同じ大きさで同じ四角形の１つの角部を切欠いた（隅切りした）形状である。また、第２の内部電極層１２２の形状は、第１の内部電極層１２１を積層方向から見た中心を対称の中心として１８０度回転させた形状（点対称な形状）である。四角柱状の積層体１０を積層方向から見ると、第１の内部電極層１２１の切欠いた部分と第２の内部電極層１２２の切欠いた部分は、四角形の対角に位置している。このような形状により、第１の内部電極層１２１および第２の内部電極層１２２の端面は、四角柱状の積層体１０の４つの側面全てに達しており、４つの側面全てが第１の側面１５１となっている。 In this case, the shape of the first internal electrode layer 121 viewed from the stacking direction is a shape that is the same size as the piezoelectric layer 11 and has one corner of the same square cut out (corner cut). The shape of the second internal electrode layer 122 is a shape (point-symmetric shape) obtained by rotating the first internal electrode layer 121 180 degrees around the center viewed from the stacking direction. When the quadrangular columnar stacked body 10 is viewed from the stacking direction, the cut-out portion of the first internal electrode layer 121 and the cut-out portion of the second internal electrode layer 122 are positioned at diagonal corners of the quadrangle. With such a shape, the end surfaces of the first internal electrode layer 121 and the second internal electrode layer 122 reach all four side surfaces of the quadrangular columnar laminate 10, and all four side surfaces are the first side surfaces. 151.
　また、この例の場合には、各側面（第１の側面１５１）において、活性領域１３と不活性領域１４とがある。この不活性領域１４は、第１の内部電極層１２１および第２の内部電極層１２２のいずれかが切欠かれていることで第１の内部電極層１２１または第２の内部電極層１２２の端面の一部が側面に達していない部分である。そして、この例では、積層方向から見て相対的に幅の広い不活性領域１４があるほうの対向する一対の側面（第１の側面１５１）の当該不活性領域１４に外部電極１７が設けられていて、この不活性領域１３に達している第１の内部電極層１２１の端面または第２の内部電極層１２２の端面と外部電極１７とが電気的に接続されている。なお、積層方向から見た不活性領域１４の幅や外部電極１７の設けられる位置については特に限定はない。 Further, in this example, there are an active region 13 and an inactive region 14 on each side surface (first side surface 151). The inactive region 14 is formed on the end surface of the first internal electrode layer 121 or the second internal electrode layer 122 by cutting off either the first internal electrode layer 121 or the second internal electrode layer 122. Part is the part that has not reached the side. In this example, the external electrode 17 is provided on the inactive region 14 of the pair of opposing side surfaces (first side surface 151) having the relatively wide inactive region 14 when viewed from the stacking direction. In addition, the end face of the first internal electrode layer 121 or the end face of the second internal electrode layer 122 reaching the inactive region 13 is electrically connected to the external electrode 17. In addition, there is no limitation in particular about the width | variety of the inactive area | region 14 seen from the lamination direction, and the position in which the external electrode 17 is provided.
　この例の場合も、被覆材１６の厚みが活性領域１３の中央部よりも活性領域１３と不活性領域１４との境界付近で厚くなっている。なお、ここでいう活性領域１３の中央部とは、積層方向から見たときの第１の側面１５１における活性領域１３の中央部（第１の側面１５１に面した活性領域１３の中央部）、言い換えれば、第１の側面１５１における第１の内部電極層１２１および第２の内部電極層１２２が達している部分の中央部のことを意味している。 Also in this example, the thickness of the covering material 16 is thicker in the vicinity of the boundary between the active region 13 and the inactive region 14 than the central portion of the active region 13. The central portion of the active region 13 referred to here is the central portion of the active region 13 in the first side surface 151 when viewed from the stacking direction (the central portion of the active region 13 facing the first side surface 151), In other words, it means the central portion of the portion of the first side surface 151 where the first internal electrode layer 121 and the second internal electrode layer 122 have reached.
　また、図９～図１１に示すように、この例の場合も、積層方向から見て、被覆材１６の厚みがなだらかに変化していてもよいし、積層方向から見て、被覆材１６の厚みが活性領域１３と不活性領域１４との境界付近よりも第１の側面１５１の端側（被覆材１６の端）で薄くなっていてもよい。 Further, as shown in FIGS. 9 to 11, also in this example, the thickness of the covering material 16 may change gently as viewed from the stacking direction, or the covering material 16 may be changed as viewed from the stacking direction. The thickness may be thinner on the end side of the first side surface 151 (the end of the covering material 16) than the vicinity of the boundary between the active region 13 and the inactive region 14.
　次に、本実施形態の積層型圧電素子１の製造方法の一例について説明する。 Next, an example of a method for manufacturing the multilayer piezoelectric element 1 of the present embodiment will be described.
　まず、圧電体層１１となるセラミックグリーンシートを作製する。具体的には、圧電セラミックスの仮焼粉末と、アクリル系，ブチラール系等の有機高分子からなるバインダーと、可塑剤とを混合してセラミックスラリーを作製する。そして、ドクターブレード法、カレンダーロール法等のテープ成型法を用いることにより、このセラミックスラリーを用いてセラミックグリーンシートを作製する。圧電セラミックスとしては圧電特性を有するものであればよく、例えば、チタン酸ジルコン酸鉛（ＰｂＺｒＯ３－ＰｂＴｉＯ３）からなるペロブスカイト型酸化物等を用いることができる。また、可塑剤としては、フタル酸ジブチル（ＤＢＰ），フタル酸ジオクチル（ＤＯＰ）等を用いることができる。 First, a ceramic green sheet to be the piezoelectric layer 11 is produced. Specifically, a ceramic slurry is prepared by mixing a calcined powder of piezoelectric ceramic, a binder made of an organic polymer such as acrylic or butyral, and a plasticizer. And a ceramic green sheet is produced using this ceramic slurry by using tape molding methods, such as a doctor blade method and a calender roll method. As the piezoelectric ceramic, any material having piezoelectric characteristics may be used. For example, a perovskite oxide made of lead zirconate titanate (PbZrO 3 -PbTiO 3 ) can be used. As the plasticizer, dibutyl phthalate (DBP), dioctyl phthalate (DOP), or the like can be used.
　次に、第１の内部電極層１２１および第２の内部電極層１２２となる導電性ペーストを作製する。具体的には、銀－パラジウム合金の金属粉末にバインダーおよび可塑剤を添加混合することによって導電性ペーストを作製する。この導電性ペーストを上記のセラミックグリーンシート上に、スクリーン印刷法を用いて第１の内部電極層１２１および第２の内部電極層１２２のパターンで塗布する。さらに、この導電性ペーストが印刷されたセラミックグリーンシートを複数枚積層し、所定の温度で脱バインダー処理を行なった後、９００～１２００℃の温度で焼成する。そして、平面研削盤等を用いて所定の形状になるよう研削処理を施すことによって、交互に積層された圧電体層１１、第１の内部電極層１２１および第２の内部電極層１２２を備えた活性部を作製する。また、第１の内部電極層１２１および第２の内部電極層１２２となる導電性ペーストを塗布していないセラミックグリーンシートを積層することで不活性部を作製する。そして、活性部と不活性部とを組み合わせることで積層体１０を製造する。 Next, a conductive paste to be the first internal electrode layer 121 and the second internal electrode layer 122 is produced. Specifically, a conductive paste is prepared by adding and mixing a binder and a plasticizer to a metal powder of a silver-palladium alloy. This conductive paste is applied on the ceramic green sheet in a pattern of the first internal electrode layer 121 and the second internal electrode layer 122 by using a screen printing method. Further, a plurality of ceramic green sheets on which this conductive paste is printed are stacked, debindered at a predetermined temperature, and then fired at a temperature of 900 to 1200 ° C. Then, the piezoelectric layer 11, the first internal electrode layer 121, and the second internal electrode layer 122 are alternately stacked by performing a grinding process so as to have a predetermined shape using a surface grinder or the like. An active part is produced. Further, the inactive portion is produced by laminating ceramic green sheets to which the conductive paste to be the first internal electrode layer 121 and the second internal electrode layer 122 is not applied. And the laminated body 10 is manufactured by combining an active part and an inactive part.
　なお、積層体１０は、上記の製造方法によって作製されるものに限定されるものではなく、圧電体層１１、第１の内部電極層１２１および第２の内部電極層１２２を複数積層してなる積層体１０を作製できれば、どのような製造方法によって作製されてもよい。 The laminated body 10 is not limited to the one produced by the above manufacturing method, and is formed by laminating a plurality of piezoelectric layers 11, first internal electrode layers 121, and second internal electrode layers 122. As long as the laminated body 10 can be produced, it may be produced by any manufacturing method.
　次に、外部電極１７を形成する。具体的には、銀や銅のような金属を含んだ導電性ペーストを用いる。これを積層体１０の側面における第１の内部電極層１２１および第２の内部電極層１２２のうちの一方の端面が導出された領域（第２の側面１５２）に焼き付けて、例えば５μｍ～７０μｍの厚さの外部電極１７を形成する。スクリーン印刷やディスペンス方式により、所定の厚みや幅に制御して形成することができる。例えば、銀を主成分とする導電性粒子とガラスとを混合したものに、バインダー，可塑剤および溶剤を加えて作製した銀ガラス含有導電性ペーストを用いる。そして、外部電極１７のパターンで積層体１０の側面にスクリーン印刷法によって印刷後、乾燥させた後、６５０～７５０℃の温度で焼き付け処理を行なう。 Next, the external electrode 17 is formed. Specifically, a conductive paste containing a metal such as silver or copper is used. This is baked on a region (second side surface 152) from which one end surface of the first internal electrode layer 121 and the second internal electrode layer 122 on the side surface of the multilayer body 10 is derived, for example, 5 μm to 70 μm. A thick external electrode 17 is formed. It can be formed by controlling to a predetermined thickness or width by screen printing or dispensing. For example, a silver glass-containing conductive paste prepared by adding a binder, a plasticizer, and a solvent to a mixture of conductive particles mainly containing silver and glass is used. Then, after printing on the side surface of the laminate 10 with a pattern of the external electrode 17 by a screen printing method and drying, a baking process is performed at a temperature of 650 to 750 ° C.
　次に、被覆材１６を形成する。具体的には、例えばエポキシ、シリコーン、ナイロンなどの樹脂を使用し、少なくとも第１の側面１５１に、印刷やディスペンス方式により、所定の厚みに制御して形成することができる。 Next, the covering material 16 is formed. Specifically, for example, a resin such as epoxy, silicone, or nylon can be used, and at least the first side surface 151 can be formed with a predetermined thickness controlled by printing or dispensing.
　ここで、積層型圧電素子１は、積層体１０の少なくとも第１の側面１５１を被覆する被覆材１６を備えていて、積層体１０の積層方向から見て、第１の側面１５１を被覆する被覆材１６の厚みが、活性領域１３の中央部よりも活性領域１３と不活性領域１４との境界付近で厚くなっている構成とするには、ディスペンサーで厚みを厚くしたい部分の塗布量が多くなるように制御しつつ塗布することで作製することができる。また、厚みを厚くしたい部分に重ね塗りすることでも、作製することができる。また、積層方向から見て、被覆材１６の厚みがなだらかに変化している形状とするには、例えばそのような形状の金型を用いてインサート成型することで、作製することができる。 Here, the multilayer piezoelectric element 1 includes a covering material 16 that covers at least the first side surface 151 of the multilayer body 10, and covers the first side surface 151 when viewed from the stacking direction of the multilayer body 10. In order to make the thickness of the material 16 thicker in the vicinity of the boundary between the active region 13 and the inactive region 14 than in the central portion of the active region 13, the amount of application of the portion where the thickness is to be increased by the dispenser increases. Thus, it can produce by apply | coating, controlling. Alternatively, it can be produced by overcoating the portion where the thickness is desired to be increased. Moreover, in order to make it the shape which the thickness of the coating | covering material 16 changes gently seeing from the lamination direction, it can produce by insert-molding using the metal mold | die of such a shape, for example.
　その後、外部電極１７に０．１～３ｋＶ／ｍｍの直流電界を印加し、積層体１０を構成する圧電体層１１を分極することによって、積層型圧電素子１が完成する。この積層型圧電素子１は、外部電極１７を介して外部の電源と接続して、圧電体層１１に電圧を印加することにより、各圧電体層１１を逆圧電効果によって大きく変位させることができる。これにより、例えばエンジンに燃料を噴射供給する自動車用燃料噴射弁として機能させることが可能となる。 Thereafter, a multilayer electric element 1 is completed by applying a direct current electric field of 0.1 to 3 kV / mm to the external electrode 17 to polarize the piezoelectric layer 11 constituting the multilayer body 10. This multilayer piezoelectric element 1 is connected to an external power source via an external electrode 17 and applies a voltage to the piezoelectric layer 11, whereby each piezoelectric layer 11 can be greatly displaced by the inverse piezoelectric effect. . This makes it possible to function as an automobile fuel injection valve that injects and supplies fuel to the engine, for example.
　次に、本実施形態の噴射装置の一例について説明する。図１２は、本実施形態の噴射装置の一例を示す概略断面図である。 Next, an example of the injection device of the present embodiment will be described. FIG. 12 is a schematic cross-sectional view illustrating an example of the injection device of the present embodiment.
　図１２に示すように、本例の噴射装置１９は、一端に噴射孔２１を有する収納容器（容器）２３の内部に上記の例の積層型圧電素子１が収納されている。 As shown in FIG. 12, in the injection device 19 of this example, the multilayer piezoelectric element 1 of the above example is accommodated in a storage container (container) 23 having an injection hole 21 at one end.
　収納容器２３内には、噴射孔２１を開閉することができるニードルバルブ２５が配設されている。噴射孔２１には流体通路２７がニードルバルブ２５の動きに応じて連通可能になるように配設されている。この流体通路２７は外部の流体供給源に連結され、流体通路２７に常時高圧で流体が供給されている。従って、ニードルバルブ２５が噴射孔２１を開放すると、流体通路２７に供給されていた流体が外部または隣接する容器、例えば内燃機関の燃料室（図示せず）に、噴射孔２１から吐出されるように構成されている。 In the storage container 23, a needle valve 25 capable of opening and closing the injection hole 21 is disposed. A fluid passage 27 is disposed in the injection hole 21 so as to be able to communicate with the movement of the needle valve 25. The fluid passage 27 is connected to an external fluid supply source, and fluid is constantly supplied to the fluid passage 27 at a high pressure. Therefore, when the needle valve 25 opens the injection hole 21, the fluid supplied to the fluid passage 27 is discharged from the injection hole 21 to the outside or an adjacent container, for example, a fuel chamber (not shown) of the internal combustion engine. It is configured.
　ニードルバルブ２５の上端部は内径が大きくなっており、収納容器２３に形成されたシリンダ２９と摺動可能なピストン３１になっている。そして、収納容器２３内には、上述した例の積層型圧電素子１がピストン３１に接して収納されている。 The upper end portion of the needle valve 25 has a large inner diameter, and is a piston 31 slidable with a cylinder 29 formed in the storage container 23. In the storage container 23, the multilayer piezoelectric element 1 of the above-described example is stored in contact with the piston 31.
　このような噴射装置１９では、積層型圧電素子１の駆動によって噴射孔２１が開閉される。具体的には、積層型圧電素子１が電圧を印加されて伸長すると、ピストン３１が押圧され、ニードルバルブ２５が噴射孔２１に通じる流体通路２７を閉塞し、流体の供給が停止される。また、電圧の印加が停止されると積層型圧電素子１が収縮し、皿バネ３３がピストン３１を押し返し、流体通路２７が開放され噴射孔２１が流体通路２７と連通して、噴射孔２１から流体の噴射が行なわれるようになっている。 In such an injection device 19, the injection hole 21 is opened and closed by driving the multilayer piezoelectric element 1. Specifically, when the multilayer piezoelectric element 1 is extended by applying a voltage, the piston 31 is pressed, the needle valve 25 closes the fluid passage 27 leading to the injection hole 21, and the supply of fluid is stopped. When the voltage application is stopped, the laminated piezoelectric element 1 contracts, the disc spring 33 pushes back the piston 31, the fluid passage 27 is opened, and the injection hole 21 communicates with the fluid passage 27. Fluid injection is performed.
　なお、積層型圧電素子１に電圧を印加することによって流体通路２７を開放し、電圧の印加を停止することによって流体通路２７を閉鎖するように構成してもよい。 Note that the fluid passage 27 may be opened by applying a voltage to the multilayer piezoelectric element 1 and the fluid passage 27 may be closed by stopping the application of the voltage.
　また、積層型圧電素子１が必ずしも収納容器２３の内部にある必要はなく、積層型圧電素子１の駆動によって収納容器２３の内部に流体の噴射を制御するための圧力が加わるように構成されていればよい。なお、本例の噴射装置１９において、流体とは、燃料，インク等の他、導電性ペースト等の種々の液体および気体が含まれる。本例の噴射装置１９を用いることによって、流体の流量および噴出タイミングを長期にわたって安定して制御することができる。 Further, the multilayer piezoelectric element 1 does not necessarily have to be inside the storage container 23, and is configured such that a pressure for controlling the ejection of fluid is applied to the interior of the storage container 23 by driving the multilayer piezoelectric element 1. Just do it. In the injection device 19 of the present example, the fluid includes various liquids and gases such as conductive paste in addition to fuel, ink, and the like. By using the ejection device 19 of this example, the flow rate and ejection timing of the fluid can be stably controlled over a long period of time.
　上記の例の積層型圧電素子１を採用した本例の噴射装置１９を内燃機関に用いれば、従来の噴射装置に比べてエンジン等の内燃機関の燃焼室に燃料をより長い期間にわたって精度よく噴射させることができる。 If the injection device 19 of the present example employing the multilayer piezoelectric element 1 of the above example is used for an internal combustion engine, the fuel is accurately injected into the combustion chamber of the internal combustion engine such as an engine over a longer period of time compared to the conventional injection device. Can be made.
　次に、本開示の燃料噴射システムの実施の形態の例について説明する。図１３は、本実施形態の燃料噴射システムの一例を示す概略図である。 Next, an example of an embodiment of the fuel injection system according to the present disclosure will be described. FIG. 13 is a schematic diagram illustrating an example of the fuel injection system of the present embodiment.
　図１３に示すように、本例の燃料噴射システム３５は、高圧流体としての高圧燃料を蓄えるコモンレール３７と、このコモンレール３７に蓄えられた高圧流体を噴射する複数の上記の例の噴射装置１９と、コモンレール３７に高圧流体を供給する圧力ポンプ３９と、噴射装置１９に駆動信号を与える噴射制御ユニット４１とを備えている。 As shown in FIG. 13, the fuel injection system 35 of this example includes a common rail 37 that stores high-pressure fuel as a high-pressure fluid, and a plurality of injection devices 19 of the above-described examples that inject the high-pressure fluid stored in the common rail 37. A pressure pump 39 for supplying a high-pressure fluid to the common rail 37 and an injection control unit 41 for supplying a drive signal to the injection device 19 are provided.
　噴射制御ユニット４１は、外部情報または外部からの信号に基づいて高圧流体の噴射の量およびタイミングを制御する。例えば、エンジンの燃料噴射に本例の燃料噴射システム３５を用いた場合であれば、エンジンの燃焼室内の状況をセンサ等で感知しながら燃料噴射の量およびタイミングを制御することができる。圧力ポンプ３９は、燃料タンク４３から流体燃料を高圧でコモンレール３７に供給する役割を果たす。例えばエンジンの燃料噴射システム３５の場合には１０００気圧～２０００気圧（約１０１ＭＰａ～約２０３ＭＰａ）、好ましくは１５００気圧～１７００気圧（約１５２ＭＰａ～約１７２ＭＰａ）の高圧にしてコモンレール３７に流体燃料を送り込む。コモンレール３７では、圧力ポンプ３９から送られてきた高圧燃料を蓄え、噴射装置１９に適宜送り込む。噴射装置１９は、前述したように噴射孔２１から一定の流体を外部または隣接する容器に噴射する。例えば、燃料を噴射供給する対象がエンジンの場合には、高圧燃料を噴射孔２１からエンジンの燃焼室内に霧状に噴射する。 The injection control unit 41 controls the amount and timing of high-pressure fluid injection based on external information or an external signal. For example, if the fuel injection system 35 of this example is used for engine fuel injection, the amount and timing of fuel injection can be controlled while sensing the state of the combustion chamber of the engine with a sensor or the like. The pressure pump 39 serves to supply fluid fuel from the fuel tank 43 to the common rail 37 at a high pressure. For example, in the case of the fuel injection system 35 of the engine, the fluid fuel is fed into the common rail 37 at a high pressure of 1000 to 2000 atmospheres (about 101 MPa to about 203 MPa), preferably 1500 to 1700 atmospheres (about 152 MPa to about 172 MPa). In the common rail 37, the high-pressure fuel sent from the pressure pump 39 is stored and sent to the injection device 19 as appropriate. As described above, the ejection device 19 ejects a certain fluid from the ejection holes 21 to the outside or an adjacent container. For example, when the target for injecting and supplying fuel is an engine, high-pressure fuel is injected from the injection hole 21 into the combustion chamber of the engine in the form of a mist.
　本例の燃料噴射システム３５によれば、高圧燃料の所望の噴射を長期にわたって安定して行なうことができる。 According to the fuel injection system 35 of this example, desired injection of high-pressure fuel can be stably performed over a long period of time.
　次に、実施例について説明する。 Next, examples will be described.
　積層型圧電素子を備えた圧電アクチュエータを以下のようにして作製した。まず、平均粒径が０．４μｍのチタン酸ジルコン酸鉛（ＰｂＺｒＯ３－ＰｂＴｉＯ３）を主成分とする圧電セラミックスの仮焼粉末、バインダーおよび可塑剤を混合したセラミックスラリーを作製した。このセラミックスラリーを用いてドクターブレード法により厚み５０μｍの圧電体層となるセラミックグリーンシートを作製した。 A piezoelectric actuator provided with a multilayer piezoelectric element was produced as follows. First, a ceramic slurry was prepared by mixing a calcined powder of a piezoelectric ceramic mainly composed of lead zirconate titanate (PbZrO 3 —PbTiO 3 ) having an average particle size of 0.4 μm, a binder, and a plasticizer. Using this ceramic slurry, a ceramic green sheet serving as a piezoelectric layer having a thickness of 50 μm was prepared by a doctor blade method.
　次に、銀－パラジウム合金にバインダーを加えて、内部電極層となる導電性ペーストを作製した。 Next, a binder was added to the silver-palladium alloy to produce a conductive paste to be an internal electrode layer.
　次に、セラミックグリーンシートの片面に、第１および第２の内部電極層となる導電性ペーストをスクリーン印刷法により印刷し、導電性ペーストが印刷されたセラミックグリーンシートを２００枚積層した。また、第１および第２の内部電極層となる導電性ペーストが印刷されたセラミックグリーンシート２００枚を中心にして、その上下に、内部電極層となる導電性ペーストが印刷されていないセラミックグリーンシート合計１５枚を積層した。そして、９８０～１１００℃で焼成し、平面研削盤を用いて所定の形状に研削して端面が５ｍｍ角の積層体を得た。 Next, on one side of the ceramic green sheet, a conductive paste serving as the first and second internal electrode layers was printed by a screen printing method, and 200 ceramic green sheets on which the conductive paste was printed were laminated. The ceramic green sheets on which the conductive paste serving as the internal electrode layer is not printed above and below the 200 ceramic green sheets printed with the conductive paste serving as the first and second internal electrode layers A total of 15 sheets were laminated. Then, it was fired at 980 to 1100 ° C. and ground to a predetermined shape using a surface grinder to obtain a laminate having an end face of 5 mm square.
　次に、積層体の側面に、銀とガラスにバインダーを混合した導電性ペーストをスクリーン印刷法により印刷し、７００℃で焼き付け処理を行なって、外部電極を形成した。 Next, a conductive paste in which a binder of silver and glass was mixed was printed on the side surface of the laminate by screen printing, and baked at 700 ° C. to form external electrodes.
　次に、外部電極の表面に、銀粉末とポリイミド樹脂を混合ペースト状にした接合材をディスペンサーにて塗布し、外部電極板を積層体の側面と平行にして取り付けた。 Next, a bonding material in the form of a mixed paste of silver powder and polyimide resin was applied to the surface of the external electrode with a dispenser, and the external electrode plate was attached in parallel with the side surface of the laminate.
　次に、一対の第１の側面にシリコーン樹脂による被覆材を形成した。 Next, a coating material made of silicone resin was formed on the pair of first side surfaces.
　ここで、比較例として、被覆材の厚みを均一に５０μｍの厚みで形成したものを用意した（試料１）。 Here, as a comparative example, a coating material having a uniform thickness of 50 μm was prepared (Sample 1).
　これに対し、実施例として、図３に示すように活性領域と不活性領域との境界付近に対向する相対的に厚い部位が断面矩形状の積層方向に延びた突起（突条部）を有するシリコーン樹脂製の被覆材を形成したものを用意した（試料２）。ここで、厚みの薄い部分の厚みは５０μｍ、厚みの厚い部分の厚み（突起の高さ）は１００μｍとした。 On the other hand, as an example, as shown in FIG. 3, a relatively thick portion facing the vicinity of the boundary between the active region and the inactive region has a protrusion (ridge portion) extending in the stacking direction having a rectangular cross section. A silicone resin coating material was prepared (Sample 2). Here, the thickness of the thin portion was 50 μm, and the thickness of the thick portion (projection height) was 100 μm.
　また、実施例として、図５に示すように活性領域と不活性領域との境界付近に対向する相対的に厚い部位が断面矩形状の積層方向に延びた突起（突条部）を有し、その厚みがなだらかに変化するシリコーン樹脂製の被覆材を形成したものを用意した（試料３）。なお、厚いところと薄いところの接続部は４５°の角度でなだらかに接続する。厚みの薄い部分は５０μｍ、厚みの厚い部分の厚み（突起の高さ）は１００μｍとした。また、積層方向から見た断面で突起は約４５°の角度で幅が狭くなるように立ち上がる形状であり、突起とそれ以外の領域との境界が丸みを帯びてなだらかになっている形状であった。 Further, as an example, as shown in FIG. 5, a relatively thick portion facing the vicinity of the boundary between the active region and the inactive region has a protrusion (ridge portion) extending in the stacking direction having a rectangular cross section, A sample in which a coating material made of silicone resin whose thickness changes gently was prepared (Sample 3). The thick and thin connection portions are gently connected at an angle of 45 °. The thin part was 50 μm, and the thick part (projection height) was 100 μm. In addition, in the cross section viewed from the stacking direction, the protrusion has a shape that rises so that the width becomes narrow at an angle of about 45 °, and the boundary between the protrusion and the other area is rounded and has a gentle shape. It was.
　試料１～試料３の積層型圧電素子に、外部電極に溶接で接合されたリード部材を介して３ｋＶ／ｍｍの直流電界を１５分間印加して、分極処理を行なった。そして、これらの積層型圧電素子に１６０Ｖの直流電圧を印加したところ、積層体の積層方向に３０μｍの変位量が得られた。 A polarization process was performed by applying a DC electric field of 3 kV / mm to the laminated piezoelectric elements of Samples 1 to 3 through a lead member welded to an external electrode for 15 minutes. When a DC voltage of 160 V was applied to these stacked piezoelectric elements, a displacement of 30 μm was obtained in the stacking direction of the stacked body.
　さらに、これらの積層型圧電素子に、温度２５℃、湿度６０％の試験環境下で、周波数１５０Ｈｚのサイン波形にて１時間駆動させ、１時間停止する冷熱サイクルを連続で５０回実施した。 Further, these laminated piezoelectric elements were continuously driven 50 times in a test environment at a temperature of 25 ° C. and a humidity of 60% with a sine waveform with a frequency of 150 Hz for 1 hour and stopped for 1 hour.
　その結果、試料１の積層型圧電素子は４５回で絶縁不良による破壊でストップした。これに対し、試料２および試料３の積層型圧電素子は破壊せず、試験終了した。なお、試験前後の変位の変化率は、試料２が－５％で、試料３が－１％となった。 As a result, the multilayer piezoelectric element of Sample 1 was stopped due to breakdown due to poor insulation at 45 times. On the other hand, the laminated piezoelectric elements of Sample 2 and Sample 3 were not destroyed and the test was completed. The displacement change rate before and after the test was -5% for sample 2 and -1% for sample 3.
　試料１の積層型圧電素子は、駆動中に積層体の活性領域と不活性領域との境界付近にクラックが発生し、絶縁抵抗が低下したことで焼損し、ストップしたものと思われる。一方、試料２および試料３の積層型圧電素子は、同様のクラックの発生はなく、絶縁性が保たれていた。 It is probable that the multilayered piezoelectric element of Sample 1 was burned out and stopped because a crack occurred near the boundary between the active region and the inactive region of the multilayer body during driving, and the insulation resistance decreased. On the other hand, the laminated piezoelectric elements of Sample 2 and Sample 3 did not generate the same cracks and maintained insulation.
　なお、試料２における被覆材では厚みが変化する箇所で応力集中によるクラックが確認されたが、試料３における被覆材では厚みが変化する箇所でクラックが確認されなかった。 In the coating material in Sample 2, cracks due to stress concentration were confirmed at locations where the thickness changed, but in the coating material in Sample 3, cracks were not confirmed at locations where the thickness changed.
　以上の結果から、実施例の積層型圧電素子によれば、長期信頼性に優れたものとなることがわかる。 From the above results, it can be seen that the multilayer piezoelectric element of the example has excellent long-term reliability.
　１・・・積層型圧電素子
　１０・・・積層体
　１１・・・圧電体層
　１２１・・・第１の内部電極層
　１２２・・・第２の内部電極層
　１３・・・活性領域
　１４・・・不活性領域
　１５１・・・第１の側面
　１５２・・・第２の側面
　１６・・・被覆材
　１７・・・外部電極
　１９・・・噴射装置
　２１・・・噴射孔
　２３・・・収納容器（容器）
　２５・・・ニードルバルブ
　２７・・・流体通路
　２９・・・シリンダ
　３１・・・ピストン
　３３・・・皿バネ
　３５・・・燃料噴射システム
　３７・・・コモンレール
　３９・・・圧力ポンプ
　４１・・・噴射制御ユニット
　４３・・・燃料タンク DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric element 10 ... Laminated body 11 ... Piezoelectric layer 121 ... 1st internal electrode layer 122 ... 2nd internal electrode layer 13 ... Active region 14 ... Inactive region 151: first side 152 ... second side 16 ... covering material 17 ... external electrode 19 ... injection device 21 ... injection hole 23 ... storage container (container)
25 ... Needle valve 27 ... Fluid passage 29 ... Cylinder 31 ... Piston 33 ... Belleville spring 35 ... Fuel injection system 37 ... Common rail 39 ... Pressure pump 41 ... Injection control unit 43 ... Fuel tank

Claims (9)

  1. 　第１の内部電極層および第２の内部電極層が圧電体層を介して交互に積層されてなり、積層方向から見て前記第１の内部電極層と前記第２の内部電極層とが重なる活性領域と、積層方向から見て前記第１の内部電極層と前記第２の内部電極層とが重ならない不活性領域とを有しているとともに、前記第１の内部電極層および前記第２の内部電極層の両方の端面が達する第１の側面を有している積層体と、
    該積層体の少なくとも前記第１の側面を被覆する被覆材とを備え、
    積層方向から見て、前記第１の側面を被覆する前記被覆材の厚みが、前記活性領域の中央部よりも前記活性領域と前記不活性領域との境界付近で厚くなっている積層型圧電素子。     The first internal electrode layer and the second internal electrode layer are alternately stacked via the piezoelectric layers, and the first internal electrode layer and the second internal electrode layer overlap each other when viewed from the stacking direction. The active region has an inactive region in which the first internal electrode layer and the second internal electrode layer do not overlap each other when viewed from the stacking direction, and the first internal electrode layer and the second internal electrode layer A laminated body having a first side surface to which both end faces of the internal electrode layer reach,
    A covering material that covers at least the first side surface of the laminate,
    A laminated piezoelectric element in which the thickness of the covering material covering the first side surface is larger in the vicinity of the boundary between the active region and the inactive region than in the central portion of the active region when viewed from the stacking direction. .
  2. 　前記積層方向から見て、前記被覆材の厚みがなだらかに変化している請求項１に記載の積層型圧電素子。 The multilayer piezoelectric element according to claim 1, wherein the thickness of the covering material changes gently as viewed from the stacking direction.
  3. 　前記積層方向から見て、前記被覆材の厚みが前記活性領域と前記不活性領域との境界付近よりも前記第１の側面の端側で薄くなっている請求項１または請求項２に記載の積層型圧電素子。 The thickness of the said coating | covering material is thinner at the end side of the said 1st side surface than the vicinity of the boundary of the said active region and the said inactive area seeing from the said lamination direction. Multilayer piezoelectric element.
  4. 　前記積層体が、前記第１の内部電極層および前記第２の内部電極層のいずれか一方のみの端面が達する第２の側面も有している請求項１乃至請求項３のうちのいずれかに記載の積層型圧電素子。 4. The device according to claim 1, wherein the stacked body also has a second side surface that reaches an end surface of only one of the first internal electrode layer and the second internal electrode layer. 5. The laminated piezoelectric element according to 1.
  5. 　前記積層体が四角柱状であって、前記第１の側面および前記第２の側面をそれぞれ一対ずつ有している請求項４に記載の積層型圧電素子。 The multilayer piezoelectric element according to claim 4, wherein the multilayer body has a quadrangular prism shape and has a pair of each of the first side surface and the second side surface.
  6. 　前記被覆材は一対の前記第１の側面および一対の前記第２の側面を全て被覆しており、積層方向から見て、一対の前記第１の側面および一対の前記第２の側面のそれぞれの被覆材の厚み変化が同じ形状で変化している請求項５に記載の積層型圧電素子。 The covering material covers all of the pair of first side surfaces and the pair of second side surfaces, and each of the pair of first side surfaces and the pair of second side surfaces as viewed from the stacking direction. The multilayer piezoelectric element according to claim 5, wherein the change in thickness of the covering material changes in the same shape.
  7. 　前記積層体が四角柱状であって、４つの側面の全てが前記第１の内部電極層および前記第２の内部電極層の両方の端面が達する第１の側面になっている請求項１乃至請求項３のうちのいずれかに記載の積層型圧電素子。 The laminated body has a quadrangular prism shape, and all four side surfaces are first side surfaces which end faces of both the first internal electrode layer and the second internal electrode layer reach. Item 4. The multilayer piezoelectric element according to any one of Items 3 to 4.
  8. 　噴射孔を有する容器と、請求項１乃至請求項７のうちのいずれかに記載の積層型圧電素子とを備え、該積層型圧電素子の駆動によって前記噴射孔が開閉される噴射装置。 An injection device comprising a container having an injection hole and the multilayer piezoelectric element according to any one of claims 1 to 7, wherein the injection hole is opened and closed by driving the multilayer piezoelectric element.
  9. 　高圧燃料を蓄えるコモンレールと、該コモンレールに蓄えられた前記高圧燃料を噴射する請求項８に記載の噴射装置と、前記コモンレールに記高圧燃料を供給する圧力ポンプと、前記噴射装置に駆動信号を与える噴射制御ユニットとを備える燃料噴射システム。 9. A common rail that stores high-pressure fuel, an injection device according to claim 8 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 a drive signal to the injection device A fuel injection system comprising an injection control unit.
PCT/JP2017/023152 2016-07-26 2017-06-23 Stacked piezoelectric element, injection device equipped with same, and fuel injection system WO2018020921A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011176114A (en) * 2010-02-24 2011-09-08 Kyocera Corp Laminated piezoelectric element and injection device including the same, as well as fuel injection system
WO2012099233A1 (en) * 2011-01-21 2012-07-26 京セラ株式会社 Laminated-type piezoelectric element, and piezoelectric actuator, injection apparatus, and fuel injection system provided with same
JP2014007253A (en) * 2012-06-22 2014-01-16 Tdk Corp Stacked piezoelectric element
JP2015179808A (en) * 2014-02-27 2015-10-08 Tdk株式会社 Piezoelectric element unit and drive device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013042658A1 (en) * 2011-09-22 2013-03-28 日本碍子株式会社 Piezoelectric/electrostrictive actuator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011176114A (en) * 2010-02-24 2011-09-08 Kyocera Corp Laminated piezoelectric element and injection device including the same, as well as fuel injection system
WO2012099233A1 (en) * 2011-01-21 2012-07-26 京セラ株式会社 Laminated-type piezoelectric element, and piezoelectric actuator, injection apparatus, and fuel injection system provided with same
JP2014007253A (en) * 2012-06-22 2014-01-16 Tdk Corp Stacked piezoelectric element
JP2015179808A (en) * 2014-02-27 2015-10-08 Tdk株式会社 Piezoelectric element unit and drive device

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