JP2011119583A - Method of manufacturing piezo-actuator, and piezo-actuator manufactured thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a piezo-actuator that can inexpensively achieve a structure in which fuel adhesion can be avoided and electric insulation can be ensured for the element without covering the outermost peripheral side of the laminate with a SUS cover. <P>SOLUTION: Adhesive 14 is applied on a surface of a sheet-shaped member 15 in advance and a sheet-shaped member 15 whose inner face is applied with the adhesive 14 is wound around a laminate 2 so as to cover the outer peripheral surface of the laminate 2. Accordingly, work for applying the adhesive 14 on the outer peripheral surface of the laminate 2 becomes easier. Then, the outermost peripheral side of the laminate 2 is covered with a heat shrinkable material 16, and the adhesive 14 is cured by heating and the heat shrinkable material 16 is shrinked. Accordingly, work for finishing the outermost peripheral side of the laminate 2 becomes easier. Consequently, there is achieved the structure in which fuel adhesion can be avoided and electric insulation can be ensured for the piezoelectric element without covering the outermost peripheral side of the laminate 2 with the SUS cover. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention mainly relates to a method for manufacturing a piezo actuator incorporated in an injector for injecting and supplying fuel to an internal combustion engine.

2. Description of the Related Art Conventionally, injectors that are opened using the extension force of a piezoelectric element are known (for example, see Patent Document 1). That is, the injector includes a piezo actuator including a laminated body of piezoelectric elements, and opens the injection hole by driving the valve body by extension of the laminated body.

By the way, in the conventional piezo actuator 100, as shown in FIG. 3, from the viewpoint of avoiding fuel adhesion to the piezoelectric element and electrical insulation, an electrically insulating adhesive is applied to the outer peripheral surface of the laminate 101 to form an annular adhesive. The adhesive layer 102 is provided, the outer peripheral side of the adhesive layer 102 is covered with the insulating material 103, and the SUS cover 105 is arranged so that the cavity 104 is formed on the outer peripheral side of the insulating material 103.

A bellows (not shown) is connected to one end of the SUS cover 105 in order to transmit the extension force of the laminated body 101 to another member while ensuring fuel adhesion avoidance and electrical insulation on the piezoelectric element. One end side of the cover 105 is sealed.

However, laser welding is required to connect the bellows to the SUS cover 105, and the manufacturing process becomes complicated. Further, since the bellows becomes a resistance against the elongation of the laminate 101, it is necessary to set the extension force of the laminate 101 in consideration of the resistance of the bellows. As a result, the laminate 101 is lengthened by the resistance of the bellows. There is a need to.

Accordingly, in view of the above-described problems caused by connecting the bellows to the SUS cover 105, it is possible to ensure fuel adhesion avoidance and electrical insulation with respect to the piezoelectric element without covering the outermost peripheral side of the laminate 101 with the SUS cover 105. There is a need for a manufacturing method that can provide the structure at a low cost.

Special table 2009-517879

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to avoid adhesion of fuel to a piezoelectric element and to prevent electric power in a piezo actuator without covering the outermost peripheral side of the laminated body with a SUS cover. The object is to provide a structure capable of ensuring insulation at low cost.

[Means of Claim 1]
The manufacturing method according to claim 1 is a method of manufacturing a piezo actuator incorporated in an injector for injecting and supplying fuel to an internal combustion engine. The outer periphery of a piezoelectric element laminate is covered with a plurality of materials to prevent fuel adhesion and An enclosing step for ensuring insulation is provided.

Further, the enclosing step includes a preparation step of applying an electrically insulating adhesive to one surface of the sheet-like member, and a sheet so that the adhesive applied to the sheet-like member is applied to the outer peripheral surface of the laminate. A first enclosing step of winding the sheet-like member around the laminate, and applying an adhesive to the outer peripheral surface of the sheet-like member wound around the laminate, and surrounding the outer periphery of the sheet-like member with a heat shrinkable material that shrinks when heated And a finishing step of heating the laminated body surrounded by the adhesive, the sheet-like member, and the heat shrinkable material to cure the adhesive and shrink the heat shrinkable material.

First, an adhesive is applied in advance to the surface of the sheet-like member, and the adhesive is applied to the laminate by winding the sheet-like member around the laminate so that the adhesive-coated surface covers the outer peripheral surface of the laminate. The work of uniformly applying to the outer peripheral surface is facilitated. In addition, when the outermost peripheral side of the laminate is finished with the SUS cover by enclosing the outermost periphery of the laminate with a heat shrinkable material and heating to cure the adhesive and shrinking the heat shrinkable material It becomes easier compared.

For this reason, in the piezo actuator, it is possible to provide a low-cost structure that can prevent the adhesion of fuel to the piezoelectric element and ensure electrical insulation without covering the outermost peripheral side of the laminated body with the SUS cover.

[Means of claim 2]
According to the manufacturing method of claim 2, the sheet-like member is a non-heat-shrinkable material that does not shrink even when heated.
Thereby, the sheet-like member is contracted in the axial direction by heating, and the adhesive applied to the outer peripheral surface of the laminate can be prevented from leaking from both axial ends of the sheet-like member.

[Means of claim 3]
According to the manufacturing method of the third aspect, the surrounding step includes a defoaming step of defoaming the coated adhesive before being cured by heating by exposing it to a reduced pressure state lower than the atmospheric pressure.
Thereby, it is possible to prevent bubbles from remaining in the adhesive layer.

[Means of claim 4]
A piezo actuator according to a fourth aspect is manufactured by the manufacturing method according to any one of the first to third aspects.

[Means of claim 5]
According to the piezo actuator of claim 5, the surface roughness of both surfaces of the sheet-like member is equal to or greater than the surface roughness of the outer peripheral surface of the laminate.
Thereby, the sheet-like member can follow the expansion and contraction of the laminate without peeling off from the adhesive layer even if the laminate is expanded or contracted in the axial direction.

[Means of claim 6]
According to the piezo actuator according to claim 6, the surface roughness of the inner peripheral surface to which the adhesive adheres is greater than or equal to the surface roughness of the outer peripheral surface of the laminate.
Thereby, even if a laminated body is expanded-contracted to an axial direction, a heat-shrink material can track expansion / contraction of a laminated body, without peeling with respect to an adhesive bond layer.

[Means of Claim 7]
According to the piezo actuator according to claim 7, the adhesive after heat curing is an elastic body.
Thereby, since the restriction | limiting with respect to the expansion-contraction of a laminated body by an adhesive agent is suppressed, the resistance of the adhesive agent with respect to the expansion | extension of a laminated body is relieve | moderated. For this reason, compared with the case where the conventional bellows is used, the axial direction length of a laminated body can be shortened reliably.

[Means of Claim 8]
According to the piezoelectric actuator described in claim 8, the adhesive is a silicon-based organic material.
This means shows one embodiment of an adhesive having elasticity by heat curing.

[Means of Claim 9]
According to the piezoelectric actuator of the ninth aspect, the sheet-like member and the heat shrinkable material are resin materials having electrical insulation.
Thereby, the electrical insulation with respect to a laminated body can further be improved.

[Means of Claim 10]
According to the piezoelectric actuator of the tenth aspect, the heat shrinkable material is a resin material having water repellency.
As a result, moisture in the fuel can be shut off on the outermost periphery side of the laminate, so that the electrical insulation with respect to the laminate can be further enhanced.

[Means of Claim 11]
According to the piezoelectric actuator of the eleventh aspect, the heat shrinkable material is a fluorine-based or silicon-based resin material.
This means shows one aspect of the heat shrinkable material.

(A) is the fragmentary sectional view of a piezoelectric actuator, (b) is the elements on larger scale of (a) (Example). It is explanatory drawing which shows the surrounding process in the manufacturing method of a piezo actuator (Example). (A) is a fragmentary sectional view of a piezoelectric actuator, (b) is the elements on larger scale of (a) (conventional example).

The manufacturing method of the embodiment is a manufacturing method of a piezo actuator incorporated in an injector for injecting and supplying fuel to an internal combustion engine. The outer periphery of a piezoelectric element laminate is covered with a plurality of materials to prevent adhesion of fuel and electrical insulation. An enclosing process is provided.

Further, the enclosing step includes a preparation step of applying an electrically insulating adhesive to one surface of the sheet-like member, and a sheet so that the adhesive applied to the sheet-like member is applied to the outer peripheral surface of the laminate. A first enclosing step of winding the sheet-like member around the laminate, and applying an adhesive to the outer peripheral surface of the sheet-like member wound around the laminate, and surrounding the outer periphery of the sheet-like member with a heat shrinkable material that shrinks when heated And a finishing step of heating the laminated body surrounded by the adhesive, the sheet-like member, and the heat shrinkable material to cure the adhesive and shrink the heat shrinkable material.

The sheet-like member is a non-heat shrinkable material that does not shrink even when heated.
Furthermore, the surrounding step has a defoaming step of defoaming the coated adhesive before being cured by heating by exposing it to a reduced pressure state lower than the atmospheric pressure.

Moreover, according to the piezo actuator manufactured by the manufacturing method of the embodiment, the surface roughness of both surfaces of the sheet-like member is equal to or greater than the surface roughness of the outer peripheral surface of the laminate.
Furthermore, the surface roughness of the inner peripheral surface to which the adhesive adheres is greater than or equal to the surface roughness of the outer peripheral surface of the laminate.

The adhesive after heat curing is an elastic body, and the adhesive is a silicon-based organic material.
Further, the sheet-like member and the heat shrink material are resin materials having electrical insulation, and the heat shrink material is a resin material having water repellency and is a fluorine-based or silicon-based resin material.

[Configuration of Example]
The configuration of the piezoelectric actuator 1 according to the embodiment will be described with reference to FIG.
The piezo actuator 1 is mounted on each cylinder of an engine (not shown), for example, and is incorporated in an injector (not shown) that directly injects fuel into a combustion chamber (not shown). It is provided so as to include the stacked body 2 of elements. Then, the piezo actuator 1 opens the injection hole (not shown) by driving the valve body (not shown) of the injector by the extension of the laminated body 2.

The piezoelectric actuator 1 includes a laminate 2 of piezoelectric elements, alumina insulators 3 and 4 that electrically insulate both ends of the laminate 2 in the axial direction, and a surrounding layer 5 that covers the outer peripheral sides of the laminate 2 and the alumina insulators 3 and 4. And a housing 7 for fixing and sealing the lead terminal 6.

The envelope layer 5 is composed of a first adhesive layer 9, a first resin layer 10, a second adhesive layer 11, and a second resin layer 12 in this order from the inner periphery to the outer periphery, and is a fuel for the laminate 2. It is provided in order to avoid adhesion and to ensure electrical insulation.
The first and second adhesive layers 9 and 11 are formed by heat-curing the same adhesive 14 (see FIG. 2), and are, for example, elastic bodies obtained by heat-curing a silicon-based organic material. .

The first resin layer 10 is formed by winding a sheet-like member 15 (see FIG. 2) in a cylindrical shape, and is formed by winding the sheet-like member 15 around the outer periphery of the laminate 2. Here, the sheet-like member 15 is made of a non-heat-shrinkable and electrically insulating resin material that does not shrink even when heated. Further, the surface roughness of both surfaces of the sheet-like member 15 is equal to or greater than the surface roughness of the outer peripheral surface of the laminate 2.

The second resin layer 12 is formed by heating a heat-shrinkable and electrically insulating cylindrical resin material that shrinks when heated (hereinafter, the resin material forming the second resin layer 12 is heated). (Referred to as shrink material 16 (see FIG. 2)). Here, the heat shrink material 16 is a resin material having water repellency, and is a fluorine-based or silicon-based resin material. And the surface roughness of the inner peripheral surface to which the adhesive agent 14 adheres out of both surfaces of the heat shrink material 16 is more than the surface roughness of the outer peripheral surface of the laminated body 2.

[Production Method of Examples]
A method of manufacturing the piezo actuator 1 of the embodiment will be described with reference to FIG.
The method for manufacturing the piezo actuator 1 includes an enclosing step of forming the enveloping layer 5 by covering the outer periphery of the laminate 2 with a plurality of materials. Moreover, the surrounding process has a preparation process, a 1st, 2nd surrounding process, a defoaming process, and a finishing process demonstrated below. In the following description, an intermediate product that does not reach the piezo actuator 1 as a final product that has undergone the finishing process and includes the laminate 2 is referred to as a laminate ASSY 18.

First, the preparation step is a step of applying the adhesive 14 to one surface of the sheet-like member 15. The adhesive 14 cut off in the preparation process forms the first adhesive layer 9 by heat curing. Moreover, application | coating of the adhesive agent 14 in a preparatory process is performed by screen printing, for example.
Next, the first surrounding step is a step of winding the sheet-like member 15 around the laminate 2 so that the adhesive 14 applied to the sheet-like member 15 is applied to the outer peripheral surface of the laminate 2. Further, the sheet-like member 15 forms the first resin layer 10.

Next, the second surrounding step is a step of applying the adhesive 14 to the outer peripheral surface of the sheet-like member 15 wound around the laminate 2 and surrounding the outer peripheral side of the sheet-like member 15 with the heat shrinkable material 16. . The adhesive 14 applied in the second surrounding process forms the second adhesive layer 11 by heat curing. Moreover, application | coating of the adhesive agent 14 in a 2nd surrounding process is performed by spraying or transcription | transfer, for example. Moreover, the heat-shrink material 16 employed in the second surrounding process is provided in a cylindrical shape in advance. And the outer peripheral side of the sheet-like member 15 is surrounded by the heat contraction material 16 by covering the outer periphery of the laminate ASSY 18 with the heat contraction material 16.

Next, the defoaming step is a step of defoaming the applied adhesive 14 before being cured by heating by exposing it to a reduced pressure state lower than the atmospheric pressure. The reduced pressure state can be created by sucking the inside of a predetermined container with a reduced pressure pump.
Finally, the finishing step is a step of heating the laminate ASSY 18 to cure the adhesive 14 and shrink the heat shrinkable material 16.

[Effects of Examples]
According to the manufacturing method of the embodiment, the adhesive 14 is applied to the surface of the sheet-like member 15 in advance, and the sheet-like member 15 is applied so that the surface to which the adhesive 14 has been applied covers the outer peripheral surface of the laminate 2. It is wound around the laminate 2. Thereby, the operation | work which apply | coats the adhesive agent 14 uniformly to the outer peripheral surface of the laminated body 2 becomes easy. Further, the outermost peripheral side of the laminate 2 is surrounded by the heat shrink material 16 and heated to cure the adhesive 14 and to shrink the heat shrink material 16. Thereby, the operation | work which finishes the outermost peripheral side of the laminated body 2 becomes easy compared with the case where it finishes with a SUS cover.

For this reason, in the piezoelectric actuator 1, the structure which can ensure the adhesion avoidance of fuel with respect to a piezoelectric element and electrical insulation can be provided at low cost, without covering the outermost periphery side of the laminated body 2 with a SUS cover.

Note that the film thickness of the adhesive 14 forming the first adhesive layer 9 is an extremely important item in securing electrical insulation, and must be strictly controlled. For this reason, when a cylindrical member is adopted instead of the sheet-like member 15 as a member forming the first resin layer 10, the laminated body ASSY 18 is obtained even if the adhesive 14 is applied to the outer periphery of the laminated body 2 with high accuracy in advance. It is necessary to cover the outer periphery of the laminate ASSY 18 with the axial center of the cylindrical member and the axial center of the cylindrical member with high accuracy.

Therefore, the sheet-like member 15 is adopted as a member constituting the first resin layer 10, the adhesive 14 is applied to the surface of the sheet-like member 15 in advance, and the sheet-like member 15 is wound around the laminate 2 as described above. Therefore, the manufacturing process is simplified and the piezo actuator 1 can be manufactured at a low cost.

The sheet-like member 15 is a non-heat-shrinkable material that does not shrink even when heated.
Thereby, the sheet-like member 15 is contracted in the axial direction by heating, and the adhesive 14 applied to the outer peripheral surface of the laminate 2 can be prevented from leaking from both axial ends of the sheet-like member 15.

Further, the surrounding step includes a defoaming step of defoaming the coated adhesive 14 before being cured by heating by exposing it to a reduced pressure state lower than the atmospheric pressure.
Thereby, it is possible to prevent bubbles from remaining in the first and second adhesive layers 9 and 11.

Further, the surface roughness of both surfaces of the sheet-like member 15 is equal to or greater than the surface roughness of the outer peripheral surface of the laminate 2.
Thereby, even if the laminated body 2 expands and contracts in the axial direction, the first resin layer 10 made of the sheet-like member 15 does not peel off from the first and second adhesive layers 9 and 11, and does not peel off the laminated body 2. Can follow expansion and contraction.

Moreover, the surface roughness of the inner peripheral surface to which the adhesive 14 adheres out of both surfaces of the heat-shrinkable material 16 is equal to or greater than the surface roughness of the outer peripheral surface of the laminate 2.
Thereby, even if the laminated body 2 expands and contracts in the axial direction, the heat-shrinkable material 16 can follow the expansion and contraction of the stacked body 2 without peeling off from the second adhesive layer 11.

The first adhesive layer 9 is an elastic body.
Thereby, since the restriction | limiting with respect to expansion / contraction of the laminated body 2 by the 1st adhesive bond layer 9 is suppressed, the resistance of the 1st adhesive bond layer 9 with respect to expansion | extension of the laminated body 2 is relieve | moderated. For this reason, compared with the case where the conventional bellows is used, the axial direction length of the laminated body 2 can be shortened reliably.

The sheet-like member 15 and the heat shrinkable material 16 are resin materials having electrical insulation.
Thereby, the electrical insulation with respect to the laminated body 2 can further be improved.
Further, the heat shrink material 16 is a resin material having water repellency.
As a result, moisture in the fuel can be shut off on the outermost periphery side of the laminate 2, so that the electrical insulation with respect to the laminate 2 can be further enhanced.

[Modification]
The aspect and manufacturing method of the piezo actuator 1 are not limited to the embodiments, and various modifications can be considered. For example, according to the piezo actuator 1 of the embodiment, the heat-shrink material 16 is provided in a cylindrical shape and is placed on the laminate ASSY 18. However, the heat-shrink material 16 is provided in a sheet shape, and the sheet-like heat shrink material is provided. The adhesive 14 may be applied to one side of the material 16 and wound around the laminate ASSY 18.

DESCRIPTION OF SYMBOLS 1 Piezo actuator 2 Laminated body 14 Adhesive 15 Sheet-like member 16 Heat shrink material

Claims (11)

In a method for manufacturing a piezo actuator incorporated in an injector for injecting and supplying fuel to an internal combustion engine,
A surrounding step of covering the outer periphery of the laminate of piezoelectric elements with a plurality of materials to avoid adhesion of fuel and ensure electrical insulation;
This siege process
A preparation step of applying an electrically insulating adhesive to one surface of the sheet-like member;
A first surrounding step of winding the sheet-like member around the laminate so that the adhesive applied to the sheet-like member is applied to the outer peripheral surface of the laminate;
A second enclosing step of applying the adhesive to the outer peripheral surface of the sheet-like member wound around the laminate, and surrounding the outer peripheral side of the sheet-like member with a heat-shrinkable material that shrinks when heated;
And a finishing step of heating the laminate surrounded by the adhesive, the sheet-like member, and the heat-shrinkable material to cure the adhesive and shrink the heat-shrinkable material. Actuator manufacturing method. In the manufacturing method of the piezo actuator according to claim 1,
The method of manufacturing a piezoelectric actuator, wherein the sheet-like member is a non-heat-shrinkable material that does not shrink even when heated. In the manufacturing method of the piezoelectric actuator of Claim 1 or Claim 2,
The method of manufacturing a piezoelectric actuator, wherein the surrounding step includes a defoaming step of defoaming the adhesive that has been applied before being cured by heating by exposing the adhesive to a reduced pressure lower than atmospheric pressure. A piezoelectric actuator manufactured by the manufacturing method according to any one of claims 1 to 3. The piezo actuator according to claim 4, wherein
The surface roughness of both surfaces of the sheet-like member is equal to or greater than the surface roughness of the outer peripheral surface of the laminate. In the piezo actuator according to claim 4 or 5,
The piezoelectric actuator according to claim 1, wherein a surface roughness of an inner peripheral surface to which the adhesive adheres is greater than or equal to a surface roughness of the outer peripheral surface of the laminate. In the piezoelectric actuator according to any one of claims 4 to 6,
A piezoelectric actuator characterized in that the adhesive after heat curing is an elastic body. The piezoelectric actuator according to claim 7,
A piezoelectric actuator characterized in that the adhesive is a silicon-based organic material. The piezoelectric actuator according to any one of claims 4 to 8, wherein
The piezoelectric actuator, wherein the sheet-like member and the heat shrinkable material are resin materials having electrical insulation. In the piezoelectric actuator according to any one of claims 4 to 9,
The piezoelectric actuator is characterized in that the heat-shrinkable material is a resin material having water repellency. The piezo actuator according to claim 9 or 10,
The piezoelectric actuator is characterized in that the heat-shrinkable material is a fluorine-based or silicon-based resin material.

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