JP2017011125A - Lamination type piezoelectric element and injection device including the same and fuel injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lamination type piezoelectric element, which makes strain less likely to occur between itself and an active part, inhibits cracks occurring therein, and is stably driven for a long time, and an injection device including the lamination type piezoelectric element, and to provide a fuel injection system.SOLUTION: An inactive part 14a located at one side has a metal containing layer 9 in which metal particles are arranged in layers. The metal containing layer 9 is connected to an external electrode 5. A lead member 8 is positioned on a connection part between the metal containing layer 9 and the external electrode 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminated piezoelectric element used as, for example, a piezoelectric drive 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.

  Conventionally, a laminated body having an active portion in which piezoelectric layers and internal electrode layers are alternately laminated and inactive at both ends, and an external electrode joined to the side surface of the laminated body and electrically connected to the internal electrode layer There is known a laminated piezoelectric element comprising: In such a laminated piezoelectric element, the external electrode is a conductive layer, an external electrode plate, and a conductive layer that joins the conductor layer and the external electrode plate to electrically connect the internal electrode layer and the external electrode plate. An adhesive bonding material layer. Further, the inactive portion has a metal-containing layer, and the lead member is joined to the external electrode plate (see, for example, Patent Document 1).

Japanese translation of PCT publication No. 2003-502869

  Here, in the multilayer piezoelectric element described in Patent Literature 1, when rapid energization is performed during driving, the connection portion between the external electrode and the lead member generates heat, and this heat generation causes an external portion of the inactive portion. Thermal expansion increases in the vicinity of the connecting portion between the electrode and the lead member. On the other hand, since the heat generation is small in the central portion of the inactive portion where the metal-containing layer is present, the thermal expansion is small. As described above, the inactive portion includes a portion having a large thermal expansion and a portion having a small thermal expansion, and the thermal expansion of the inactive portion becomes non-uniform. As a result, strain is generated between the inactive portion and the active portion, cracks are generated, the amount of displacement is reduced, and the durability may be deteriorated.

  Further, even in an injection device and a fuel injection system provided with such a laminated piezoelectric element, there is a possibility that it cannot be driven stably for a long period of time.

  The present invention has been devised in view of the above-mentioned problems, and its purpose is to prevent distortion from occurring between the inactive part and the active part, and to suppress cracks and to stabilize for a long time. And a fuel injection system including the stacked piezoelectric element that is driven by the fuel injection system.

  The multilayer piezoelectric element of the present invention is a non-conducting structure in which a plurality of piezoelectric layers arranged on both ends in the stacking direction of the active portion and the active portion in which a plurality of piezoelectric layers and internal electrode layers are alternately stacked. A laminated body having an active portion, and a pair of external electrodes provided on a side surface of the laminated body from the active portion to at least one of the inactive portions, and the internal electrode layers are electrically connected alternately every other layer; A lead member connected to each of the pair of external electrodes provided in one of the inactive portions, and the one inactive portion has a metal-containing layer in which a plurality of metal particles are arranged in layers. In addition, the metal-containing layer is connected to the external electrode, and the lead member is located on a connection portion between the metal-containing layer and the external electrode.

In addition, the ejection device of the present invention includes a container having an ejection hole and the multilayer piezoelectric element, and fluid stored in the container is discharged from the ejection hole by driving the multilayer piezoelectric element. It is characterized by that.

  The fuel injection system of the present invention includes a common rail that stores high-pressure fuel, the 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 And an injection control unit for supplying a drive signal to the apparatus.

  According to the multilayer piezoelectric element of the present invention, since the strain due to thermal expansion between the active part and the active part becomes small, cracks are less likely to enter the active part, so the displacement is stable for a long period of time and durability is improved. To do.

  Moreover, according to the injection device and the fuel injection system provided with the above-described multilayer piezoelectric element, the multilayer piezoelectric element has excellent durability, and can be driven stably for a long period of time.

It is a schematic longitudinal cross-sectional view which shows an example of embodiment of the lamination type piezoelectric element of this invention. It is a schematic longitudinal cross-sectional view which shows an example of embodiment of the lamination type piezoelectric element of this invention. It is a schematic longitudinal cross-sectional view which shows an example of embodiment of the lamination type piezoelectric element of this invention. It is a rough sectional view showing an example of an embodiment of an injection device of the present invention. It is a schematic block diagram which shows an example of embodiment of the fuel-injection system of this invention.

  Hereinafter, an example of an embodiment of a multilayer piezoelectric element of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic longitudinal sectional view showing an example of an embodiment of a multilayer piezoelectric element of the present invention.

  A laminated piezoelectric element 1 shown in FIG. 1 includes a laminated body 10 in which a piezoelectric layer 11 and an internal electrode layer 12 are laminated, and an external part joined to the side surface of the laminated body 10 and electrically connected to the internal electrode layer 12. And an electrode 5. The external electrode 5 is a conductive bonding material layer that electrically connects the internal electrode layer 12 and the external electrode plate 2 by bonding the conductive layer 4, the external electrode plate 2, and the conductive layer 4 and the external electrode plate 2. 3 is included. Note that a lead member 8 is connected to the external electrode 5.

  The laminated body 10 includes an active portion 13 in which a plurality of piezoelectric layers 11 and internal electrode layers 12 are laminated, and a piezoelectric layer 11 that is located outside the active portion 13 and provided at both ends in the laminating direction of the laminated body 10. And an inactive portion 14. The laminated body 10 is formed in a rectangular parallelepiped shape having, for example, a length of 0.5 to 10 mm, a width of 0.5 to 10 mm, and a height of 1 to 100 mm.

The piezoelectric layer 11 is formed of a ceramic 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 to 250 μm.

The internal electrode layer 12 is formed by simultaneous firing with ceramics forming the piezoelectric layer 11, and is alternately stacked with the piezoelectric layers 11 so as to sandwich the piezoelectric layers 11 from above and below. Is arranged to apply a driving voltage to the piezoelectric layer 11 sandwiched between them. As this forming material, for example, a conductor mainly composed of a silver-palladium alloy that can be fired at a low temperature, or a conductor containing copper, platinum, or the like can be used. In the example shown in FIG. 1, the positive electrode and the negative electrode (or the ground electrode) are alternately led out to a pair of opposite side surfaces of the stacked body 10, and the pair of conductor layers 4 provided on the side surfaces of the stacked body 10 are electrically connected. Connected. The internal electrode layer 12 has a thickness of 0.1 to 5 μm, for example.

  The external electrode 5 is obtained by bonding the external electrode plate 2 via the conductor layer 4 and the conductive bonding material layer 3 and is electrically connected to the internal electrode layer 12. Specifically, the external electrode plates 2 are respectively provided on the opposing side surfaces of the multilayer body 10 and are electrically connected to the internal electrode layer 12 by the conductor layer 4 and the conductive bonding material layer 3. The external electrode plate 2 is made of a metal flat plate such as copper, iron, stainless steel, phosphor bronze, etc., for example, having a width of 0.5 to 10 mm and a thickness greater than that of the conductor layer 4 or the conductive bonding material layer 3. What was formed in 0.1-0.3 mm is used. Note that the external electrode plate 2 was processed into, for example, a shape having a slit in the width direction or a mesh shape in order to obtain an effect of relieving not only the plate-like metal plate but also the stress caused by the expansion and contraction of the laminate 10. A metal plate or the like can also be employed.

  The conductor layer 4 is electrically connected to the internal electrode layer 12 and is made of a silver paste. In order to strengthen the bonding with the laminate 10, powder constituting the laminate 10 may be added as a filler to the silver paste.

  The conductive bonding material layer 3 is provided from the active portion 13 to the inactive portion 14 on the opposite side surface of the laminate 10, and electrically connects the conductor layer 4 on the side surface of the laminate 10 and the external electrode plate 2. ing. The conductive bonding material layer 3 is preferably made of a conductive adhesive made of an epoxy resin or a polyimide resin containing a metal powder having good conductivity such as Ag powder or Cu powder.

  In the multilayer piezoelectric element 1 of the present embodiment, the metal-containing layer 9 in which a plurality of metal particles are arranged in layers is provided in one inactive portion 14a (the upper inactive portion in FIG. 1). The metal-containing layer 9 is connected to the conductor layer 4 of the external electrode 5, and the lead member 8 is provided on the connection portion between the metal-containing layer 9 and the external electrode 5. In FIG. 1, the other inactive part 14 b illustrates a configuration in which the metal-containing layer 9 is not provided. In the following description, when the inactive portion is simply described, it will be described as the inactive portion 14, and when each inactive portion is described, it will be described as the inactive portions 14a and 14b, respectively.

  The metal-containing layer 9 is a layer including a plurality of metal particles provided inside the inactive portion 14, and the metal particles are arranged in layers. Further, at least one end of the metal-containing layer 9 is connected to the conductor layer 4.

  The lead member 8 is connected to the external electrode plate 2 on the extension of the connecting portion between the metal-containing layer 9 and the conductor layer 4. That is, at least a part of the lead member 8 is located on the extension of the metal-containing layer 9, and the lead member 8 connected to the external electrode plate 2 extends from the end of the multilayer piezoelectric element 1 in the stacking direction. It is provided to do.

The metal-containing layer 9 is a conductor composed mainly of a silver-palladium alloy that can be fired at a low temperature as metal particles, or a conductor containing copper, platinum, etc., and the piezoelectric layer 11, for example, lead zirconate titanate (PbZrO). It is a layer that does not function as an internal electrode, in which a perovskite oxide composed of _3- PbTiO ₃ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), and the like are mixed as fillers. The metal-containing layer 9 has a thickness of, for example, 0.1 to 5 μm. Moreover, the particle diameter of a metal particle is 0.5-10 micrometers in diameter, for example.

The lead member 8 is for electrical connection with the outside, and it is desirable to use a core wire such as a copper wire and to have the surface of the core wire silver-plated for soldering. The lead member 8 is connected to the core wire at the connection portion connected to the external electrode plate 2, and from the tip of the connection portion connected to the external electrode plate 2, the electric wire does not come into contact with the outside at the time of driving and does not short-circuit. An insulating coating is applied to the core wire. The coating may be a general one such as PTFE (polytetrafluoroethylene).

  Thus, since the metal-containing layer 9 is connected to the external electrode 5 and the lead member 8 is located on the connection portion between the metal-containing layer 9 and the external electrode 5, the metal-containing layer 9 is Therefore, heat conduction to the inactive part 14 is improved, and non-uniformity of thermal expansion of the inactive part 14 is improved. Therefore, since the strain due to thermal expansion between the active portion 13 and the active portion 13 is reduced, it is difficult for cracks to enter between the inactive portion 14 and the active portion 13, the displacement amount is stabilized for a long period of time, and durability is improved.

  Furthermore, as shown in FIG. 2, it can also be set as the structure by which the metal containing layer 9 was each pulled out by both the side surfaces which the inactive part 14 opposes. That is, since the metal-containing layer 9 is connected to the external electrodes 5 on both sides, and the lead member 8 is provided on the connection part, the heat conduction to the inactive part 14 is further improved, and the thermal expansion of the inactive part 14 is achieved. Is further improved. As a result, since the strain due to thermal expansion between the inactive part 14 and the active part 13 is further reduced, it becomes difficult for cracks to enter between the inactive part 14 and the active part 13, and the displacement is more stable for a long period of time. And durability is improved. FIG. 2 shows an example in which one metal-containing layer 9 in which the lead members 8 are positioned on the extension lines at both ends is provided. However, the metal-containing layer in which the lead members 8 are positioned on the extension lines at both ends is shown. There may be a plurality of layers 9.

  Furthermore, as shown in FIG. 3, the inactive portion 14 a includes a plurality of metal-containing layers 9, and the metal-containing layers 9 may be alternately drawn out to the opposite side surfaces of the inactive portion 14. it can. By alternately pulling out the metal-containing layers 9 to the opposite side surfaces of the inactive part 14a, heat is easily transmitted to the piezoelectric layer 11 of the inactive part 14a because there are a plurality of metal-containing layers 9, and the inactive part 14 The thermal expansion non-uniformity is further improved. As a result, the strain due to thermal expansion between the inactive part 14a and the active part 13 is reduced, so that it is difficult for cracks to enter between the inactive part 14a and the active part 13, so that the displacement is more stable for a long time. And durability is improved.

  Furthermore, the plurality of metal particles constituting the metal-containing layer 9 may be arranged in layers by being connected at least partially directly or via piezoelectric particles contained in the inactive part. That is, at least some of the plurality of metal particles are directly connected to each other, or at least some of the plurality of metal particles are connected to each other through the piezoelectric particles. The presence of the metal particles in such a form makes it easier for heat to be transferred to the piezoelectric layer 11 of the inactive portion 14a via the metal particles, and the non-uniformity of thermal expansion of the inactive portion 14 is further improved. The Thereby, the amount of displacement is stabilized for a long time, and durability is improved. The particle size of the piezoelectric particles is, for example, 0.1 to 10 μm in diameter.

  Further, the plurality of metal particles in the metal-containing layer 9 may be arranged in layers by being connected via piezoelectric particles in which at least a part thereof is continuous. That is, some of the plurality of metal particles are connected to each other via a plurality of continuous piezoelectric particles. Since the piezoelectric particles of the same material are thus continuous, the adhesive strength is maintained, and cracks are unlikely to occur in the metal-containing layer 9, so that the displacement is stabilized for a long period of time and the durability is improved.

Furthermore, the thickness of the other inactive part 14b can be made thinner than the thickness of the one inactive part 14a. That is, the thickness of the inactive portion 14b to which the lead member 8 is not connected is thinner than the thickness of the inactive portion 14a to which the lead member 8 is connected, so that the inactive portion 14b is deformed as the active portion 13 expands and contracts. Is small, and the speed at which the force generated by the expansion and contraction is transmitted, that is, the response speed becomes fast, which is preferable. The thickness of the other inactive portion 14b is preferably 1/2 to 1/4 of the thickness of the one inactive portion 14a. When the thickness of the other inactive portion 14b is 1/2 or more of the thickness of the one inactive portion 14a, it is difficult to sufficiently increase the response speed. If the thickness of the other inactive portion 14b is ¼ or less of the thickness of the one inactive portion 14a, the thickness of the other inactive portion 14b becomes too thin, and the inactivity accompanying the expansion / contraction of the active portion 13 is caused. This is not preferable because the deformation of the portion 14b becomes large.

  Furthermore, the thickness of the other inactive portion 14 b can be made larger than the thickness of each piezoelectric layer 11 constituting the active portion 13. That is, since the thickness of the inactive portion 14b to which the lead member 8 is not connected is thicker than the thickness of one layer of the piezoelectric layer 11 of the active portion 13, heat is hardly transmitted to the inactive portion 14b. As the heat accumulates, the temperature of the active part 13 can be kept warm. Similarly, the thickness of one inactive portion 14 a may be made larger than the thickness of each piezoelectric layer 11 constituting the active portion 13.

  The thickness of the other inactive portion 14 b is preferably 2 to 20 times the thickness of one layer of the piezoelectric layer 11 of the active portion 13. If the thickness of the other inactive portion 14b is less than twice the thickness of the piezoelectric layer 11 of the active portion 13, heat is easily transferred to the inactive portion 14b, and heat is not easily accumulated in the active portion 13. It becomes difficult to keep the active portion 13 warm. On the other hand, if the thickness of the other inactive portion 14b is 20 times or more the thickness of the piezoelectric layer 11 of the active portion 13, the thickness of the other inactive portion 14b becomes too thick, and the response speed becomes slow. It is not preferable.

  Furthermore, it is desirable that the other inactive part 14 b does not have the metal-containing layer 9. That is, by not providing the metal-containing layer 9 in the inactive portion 14b to which the lead member 8 is not connected, the inactive portion 14a to which the lead member 8 is connected becomes harder and the response speed becomes faster. Further, since the metal-containing layer 9 is not provided in the other inactive portion 14b, the heat drawn by the metal-containing layer 9 is reduced, and the temperature of the active portion 13 is constant, so that each piezoelectric layer 11 of the active portion 13 is constant. The amount of displacement is stably obtained, and the durability is improved.

  Next, a method for manufacturing the multilayer piezoelectric element 1 of the present embodiment will be described.

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.

  Next, a conductive paste to be the internal electrode layer 12 is produced. Specifically, a conductive paste is prepared by adding and mixing a binder and a plasticizer to a silver-palladium alloy metal powder. This conductive paste is applied on the ceramic green sheet in the pattern of the internal electrode layer 12 using a screen printing method.

Next, a non-conductive paste that becomes the metal-containing layer 9 is produced. Specifically, a binder and a plasticizer are added to and mixed with a metal powder of a silver-palladium alloy, and the same as the ceramic green sheet, for example, a perovskite oxide made of lead zirconate titanate (PbZrO ₃ -PbTiO ₃ ), etc. A non-conductive paste is produced by adding. This non-conductive paste is applied on the ceramic green sheet using a screen printing method.

Furthermore, after laminating a plurality of ceramic green sheets printed with the conductive paste and the non-conductive paste so as to be in a predetermined laminated state and performing a binder removal treatment at a predetermined temperature, a temperature of 900 to 1200 ° C. The laminated body 10 is manufactured by baking and performing a grinding process so as to have a predetermined shape using a surface grinder or the like. The active part 13 is produced by alternately laminating ceramic green sheets not coated with a conductive paste and ceramic green sheets coated with a conductive paste. The inactive part 14 is produced by laminating a ceramic green sheet not coated with a conductive paste and a ceramic green sheet coated with a non-conductive paste. By combining the active part 13 and the inactive part 14, the laminate 10 including the active part 13 and the inactive part 14 positioned at both upper and lower ends of the active part 13 is manufactured.

  The laminate 10 is not limited to the one produced by the above manufacturing method, and any laminate 10 can be produced as long as the laminate 10 formed by laminating a plurality of piezoelectric layers 11 and internal electrode layers 12 can be produced. It may be produced by a manufacturing method.

  Next, the conductor layer 4 is provided on the side surface of the multilayer body 10. A conductor layer paste in which glass powder or lead zirconate titanate powder is mixed with Ag powder is applied to the side surface of the laminate 10 by screen printing and baked on the side surface of the laminate 10 at a temperature of 550 to 650 ° C. Thus, the conductor layer 4 can be provided on the side surface of the multilayer body 10.

  Next, the external electrode plate 2 is connected to the conductor layer 4 on the side surface of the multilayer body 10 through the conductive bonding material layer 3 and fixed.

  The conductive bonding material layer 3 is formed to a thickness of 5 to 70 μm using a conductive adhesive made of an epoxy resin or a polyimide resin containing a metal powder having good conductivity such as Ag powder or Cu powder. It can be formed by controlling to a predetermined thickness and width by screen printing or dispensing method.

  The external electrode plate 2 is made of a metal flat plate such as copper, iron, stainless steel, phosphor bronze, and is formed to have a width of 0.5 to 10 mm and a thickness of 0.1 to 0.3 mm, for example. Here, for example, to form the external electrode plate 2 with a slit or a mesh shape in the width direction, the external electrode plate 2 is punched with a punching die or a laser to have a slit shape or a mesh shape with the external electrode plate 2. A method such as processing may be used.

  The lead member 8 is joined to the external electrode plate 2 in the external electrode by soldering or welding.

  Thereafter, a direct current electric field of 0.1 to 3 kV / mm is applied to the lead member 8 to polarize the piezoelectric layer 11 constituting the multilayer body 10, thereby completing the multilayer piezoelectric element 1. The laminated piezoelectric element 1 is connected to an external power source through the conductor layer 4, the conductive bonding material layer 3, the external electrode plate 2, and the lead member 8, and by applying a voltage to the piezoelectric layer 11, Each piezoelectric layer 11 can be largely 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.

  Next, the example of embodiment of the injection device of the present invention is explained. FIG. 4 is a schematic sectional view showing an example of the embodiment of the injection device of the present invention.

  As shown in FIG. 4, in the injection device 19 of this example, the multilayer piezoelectric element 1 of the above example is stored inside a storage container (container) 23 having an injection hole 21 at one end.

A needle valve 25 that can open and close the injection hole 21 is provided in the storage container 23. 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 of the needle valve 25 has a large inner diameter, and is a piston 31 that can slide 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.

  In such an injection device 19, 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. The 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.

  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.

  The injection device 19 of this example includes a container 23 having an injection hole 21 and the multilayer piezoelectric element 1 of the above example, and the fluid filled in the container 23 is ejected by driving the multilayer piezoelectric element 1. You may be comprised so that it may discharge from the hole 21. FIG. That is, the multilayer piezoelectric element 1 does not necessarily need to be inside the container 23, and may be configured to apply pressure for controlling the ejection of fluid to the inside of the container 23 by driving the multilayer piezoelectric element 1. Good. 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.

  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.

  Next, the example of embodiment of the fuel-injection system of this invention is demonstrated. FIG. 5 is a schematic diagram showing an example of an embodiment of the fuel injection system of the present invention.

  As shown in FIG. 5, 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 an engine fuel injection system 35, 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.

  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.

  In the above description, an example in which the inactive portion 14a provided with the metal-containing layer 9 and the inactive portion 14b provided with no metal-containing layer 9 has been shown. The inactive portion 14a provided with the layer 9 may be used.

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 diameter 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.

Next, a binder was added to the silver-palladium alloy to produce a conductive paste to be an internal electrode layer. Moreover, a non-conductive paste to be a metal-containing layer was prepared by adding a binder to a calcined powder of piezoelectric ceramics mainly composed of a silver-palladium alloy and lead zirconate titanate (PbZrO ₃ —PbTiO ₃ ).

  Next, a conductive paste serving as an internal electrode layer was printed on one side of the ceramic green sheet by a screen printing method, and 200 ceramic green sheets printed with the conductive paste were laminated. One inactive portion was laminated by sandwiching a ceramic green sheet on which a non-conductive paste was printed, with five sheets not printed on top and bottom.

  The 200 inactive ceramic green sheets on which the conductive paste to be the internal electrode layer is printed are printed on the upper side with one inactive portion sandwiched between the ceramic green sheets on which the non-conductive paste is printed, and on the lower side. The other inert part, which was laminated with only the non-sheets, was laminated and laminated. And it baked at 980-1100 degreeC, it ground to the predetermined shape using the surface grinder, and obtained the 5 mm square laminated body.

  Next, a paste containing Ag powder and a glass component was applied to the surface of the laminate by screen printing, and baked at 580 to 630 ° C. to form a conductor layer.

  Next, a conductive bonding material in the form of a mixed paste of Ag powder and polyimide resin was applied to the surface of the laminate by dispensing, and an external electrode plate welded with a lead member was connected to the surface of the laminate and fixed.

  Here, as shown in FIG. 1, the sample 1 has a structure in which a metal-containing layer is included in the inactive part, one side is joined to the external electrode, and a lead member is provided on the upper part.

  Furthermore, as shown in FIG. 2, the sample 2 has a structure in which both sides are joined to the external electrode, and a lead member is provided on the structure.

  Further, as shown in FIG. 3, the sample 3 has a structure in which the inactive portion includes two metal-containing layers, and the metal-containing layers are alternately drawn out on the opposite side surfaces of the inactive portion, and leads are formed above the inactive portion. The structure is provided with members.

In addition, a laminated piezoelectric element (sample 4) of a comparative example was also produced. This multilayer piezoelectric element has a structure in which the metal-containing layer is located inside the inactive portion, the end of the metal-containing layer is not exposed to the side surface of the multilayer body, and is not joined to the external electrode, and the lead member is on the upper portion thereof. It has a provided structure.

  These laminated piezoelectric elements were subjected to polarization treatment by applying a DC electric field of 3 kV / mm to the external electrode plate 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.

  Further, an endurance test was performed in which an alternating voltage of 0 V to +160 V was applied at a frequency of 100 Hz in an oven at 110 ° C. and continuously driven.

As a result, the laminated piezoelectric element of Sample 4 as a comparative example was cracked in the active portion and the inactive portion by 1 × 10 ⁶ continuous driving, and stopped driving after 1 × 10 ⁷ times.

On the other hand, the laminated piezoelectric elements of sample 1, sample 2, and sample 3, which are examples of the present invention, were driven without cracks even after continuous driving 1 × 10 ⁸ times. .

  From the above results, it can be seen that according to the present invention, a multilayer piezoelectric element having excellent long-term durability can be realized.

DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric element 10 ... Laminated body 11 ... Piezoelectric layer 12 ... Internal electrode layer 13 ... Active part 14 ... Inactive part 14a .. One inactive part 14b .... The other inactive part 2 ... External electrode plate 3 ... Conductive bonding material layer 4 ... Conductor layer 5 ... External electrode 8 ... Lead member 9 ... Metal-containing layer

Claims (10)

A laminated body having an active portion in which a plurality of piezoelectric layers and internal electrode layers are alternately laminated, and an inactive portion in which a plurality of piezoelectric layers respectively disposed at both ends in the lamination direction of the active portion are laminated;
A pair of external electrodes provided on the side surface of the laminate from the active portion to at least one inactive portion, and the internal electrode layers are electrically connected alternately every other layer;
A lead member connected to each of the pair of external electrodes provided in one of the inactive portions,
One of the inactive portions has a metal-containing layer in which a plurality of metal particles are arranged in layers, the metal-containing layer is connected to the external electrode, and the metal-containing layer and the external electrode A multilayer piezoelectric element, wherein the lead member is positioned on a connection portion.   2. The multilayer piezoelectric element according to claim 1, wherein the metal-containing layer is drawn out on both opposing side surfaces of the inactive portion. The inactive part includes a plurality of the metal-containing layers,
2. The multilayer piezoelectric element according to claim 1, wherein the plurality of metal-containing layers are alternately drawn on opposite side surfaces of the inactive portion.   The plurality of the metal particles are arranged in a layered manner in which at least some of them are connected directly or via piezoelectric particles contained in the inactive part. The multilayer piezoelectric element according to any one of the above.   The stacked type according to any one of claims 1 to 3, wherein the plurality of metal particles are connected in layers through the piezoelectric particles at least part of which are continuous with each other. Piezoelectric element.   6. The multilayer piezoelectric element according to claim 1, wherein the thickness of the other inactive part is thinner than the thickness of the one inactive part.   7. The stacked piezoelectric device according to claim 1, wherein a thickness of the other inactive portion is larger than a thickness of each of the piezoelectric layers constituting the active portion. element.   The stacked piezoelectric element according to claim 1, wherein the other inactive part does not have the metal-containing layer.   A container having an injection hole and the multilayer piezoelectric element according to any one of claims 1 to 8, wherein the fluid stored in the container is driven by the multilayer piezoelectric element to form the injection hole. An ejection device characterized by being discharged from the nozzle.   A common rail for storing high-pressure fuel, the injection device according to claim 9 for injecting the high-pressure fuel stored in the common rail, a pressure pump for supplying the high-pressure fuel to the common rail, and a drive signal for the injection device A fuel injection system comprising an injection control unit.

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