WO2018020921A1 - Élément piézoélectrique empilé, dispositif d'injection équipé dudit élément, et système d'injection de combustible - Google Patents

Élément piézoélectrique empilé, dispositif d'injection équipé dudit élément, et système d'injection de combustible 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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English (en)
Japanese (ja)
Inventor
新作 里井
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京セラ株式会社
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Priority to JP2018529448A priority Critical patent/JP6698843B2/ja
Publication of WO2018020921A1 publication Critical patent/WO2018020921A1/fr

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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.

Abstract

Un élément piézoélectrique empilé 1 selon la présente invention comprend une région active 13 dans laquelle une première couche d'électrode interne 121 et une seconde couche d'électrode interne 122 se chevauchent l'une sur l'autre lorsqu'elles sont vues à partir de la direction d'empilement, et une région inerte 14 dans laquelle la première couche d'électrode interne 121 et la seconde couche d'électrode interne 122 ne se chevauchent pas l'une sur l'autre lorsqu'elles sont vues à partir la direction d'empilement. Cet élément piézoélectrique empilé 1 comprend également une première surface latérale 151 dont les faces d'extrémité de la première couche d'électrode interne 121 et de la seconde couche d'électrode interne 122 viennent en contact. Cet élément piézoélectrique empilé 1 est en outre pourvu d'un matériau de recouvrement 16 qui recouvre au moins la première surface latérale 151 d'un empilement 10; et l'épaisseur du matériau de recouvrement 16 recouvrant la première surface latérale 151 autour de la limite entre la région active 13 et la région inerte 14 est plus épaisse que l'épaisseur de celle-ci dans la partie centrale de la région active 13 lorsqu'elle est vue à partir de la direction d'empilement.
PCT/JP2017/023152 2016-07-26 2017-06-23 Élément piézoélectrique empilé, dispositif d'injection équipé dudit élément, et système d'injection de combustible WO2018020921A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011176114A (ja) * 2010-02-24 2011-09-08 Kyocera Corp 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
WO2012099233A1 (fr) * 2011-01-21 2012-07-26 京セラ株式会社 Elément piézoélectrique de type stratifié, actionneur piézoélectrique, appareil d'injection et système d'injection de carburant muni de celui-ci
JP2014007253A (ja) * 2012-06-22 2014-01-16 Tdk Corp 積層型圧電素子
JP2015179808A (ja) * 2014-02-27 2015-10-08 Tdk株式会社 圧電素子ユニットおよび駆動装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2765621A4 (fr) * 2011-09-22 2015-08-05 Ngk Insulators Ltd Actionneur piézoélectrique/électrostrictif

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011176114A (ja) * 2010-02-24 2011-09-08 Kyocera Corp 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
WO2012099233A1 (fr) * 2011-01-21 2012-07-26 京セラ株式会社 Elément piézoélectrique de type stratifié, actionneur piézoélectrique, appareil d'injection et système d'injection de carburant muni de celui-ci
JP2014007253A (ja) * 2012-06-22 2014-01-16 Tdk Corp 積層型圧電素子
JP2015179808A (ja) * 2014-02-27 2015-10-08 Tdk株式会社 圧電素子ユニットおよび駆動装置

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