阅读说明：本技术 压电式阀以及该压电式阀的制造方法 (Piezoelectric valve and method for manufacturing the same ) 是由 伊藤隆文 松下忠史 樋口俊郎 徐世杰 水野义宣 于 2020-01-22 设计创作，主要内容包括：本发明提供一种压电式阀,能够防止使用时层叠型压电元件的破损片与压缩气体一起喷出,或者即使在高湿环境下使用的情况下,也能够防止湿气侵入层叠型压电元件而使寿命变短,另外,能够防止层叠型压电元件的动作被妨碍而使行程变小或者不能进行准确的动作。压电式阀利用层叠型压电元件的位移进行阀的开闭,且具备：阀主体,其具有接收从外部供给的压缩气体的气体压力室；以及驱动器,其具有阀芯、将阀芯的动作所需的驱动力作为位移而产生的层叠型压电元件以及使层叠型压电元件的位移放大并作用于阀芯的位移放大机构,且配设于阀主体的内部,该压电式阀的特征在于,层叠型压电元件在与驱动器一体化的状态下表面被硅酮覆盖。(The invention provides a piezoelectric valve which can prevent the damage piece of a laminated piezoelectric element from being ejected together with compressed gas when in use, or prevent moisture from invading the laminated piezoelectric element to shorten the service life even under the condition of use in high humidity environment, and can prevent the action of the laminated piezoelectric element from being obstructed to reduce the stroke or prevent accurate action. The piezoelectric valve opens and closes a valve by displacement of a laminated piezoelectric element, and includes: a valve main body having a gas pressure chamber that receives compressed gas supplied from the outside; and an actuator which has a valve element, a multilayer piezoelectric element which generates a driving force required for the operation of the valve element as a displacement, and a displacement amplification mechanism which amplifies the displacement of the multilayer piezoelectric element and acts on the valve element, and which is disposed inside the valve body, wherein the surface of the multilayer piezoelectric element is covered with silicone in a state of being integrated with the actuator.)

1. A piezoelectric valve which opens and closes a valve by utilizing displacement of a laminated piezoelectric element, comprising:

a valve main body having a gas pressure chamber that receives compressed gas supplied from the outside; and

an actuator which has a valve element, a multilayer piezoelectric element that generates a driving force required for the operation of the valve element as a displacement, and a displacement amplification mechanism that amplifies the displacement of the multilayer piezoelectric element and applies the amplified displacement to the valve element, and which is disposed inside the valve body,

the piezoelectric type valve described above is characterized in that,

the surface of the multilayer piezoelectric element is covered with silicone in a state of being integrated with the actuator.

2. The piezoelectric valve according to claim 1,

the surface of the multilayer piezoelectric element is covered with silicone filled between a pair of projecting strips located on both sides of the multilayer piezoelectric element in the longitudinal direction with a gap therebetween.

3. The piezoelectric valve according to claim 2,

further comprises a plate disposed inside the valve body,

the driver is fixed on the plate and is arranged in the valve main body together with the plate,

the pair of projecting pieces are provided on the surface of the plate, and when the actuator is fixed to the plate, the pair of projecting pieces are located on both sides in the longitudinal direction of the multilayer piezoelectric element with a gap therebetween,

the surface of the laminated piezoelectric element is covered with silicone filled between the pair of projecting strips in a state where the actuator is fixed to the plate.

4. The piezoelectric valve according to claim 3,

the displacement amplification mechanism is formed of a metal material, and wiring for supplying power to the laminated piezoelectric element is molded on the plate,

the electrodes of the wirings exposed from the plate are covered with an insulating material in a state of being connected to leads of the multilayer piezoelectric element.

5. The piezoelectric valve according to any one of claims 1 to 4,

the displacement amplification mechanism is formed of a metal material,

the lead of the multilayer piezoelectric element is disposed on an insulating film attached to a surface of the displacement amplifying mechanism.

6. A method for manufacturing a piezoelectric valve that opens and closes a valve by utilizing displacement of a laminated piezoelectric element, the method comprising:

a valve main body having a gas pressure chamber that receives compressed gas supplied from the outside; and

an actuator which has a valve element, a multilayer piezoelectric element that generates a driving force required for the operation of the valve element as a displacement, and a displacement amplification mechanism that amplifies the displacement of the multilayer piezoelectric element and applies the amplified displacement to the valve element, and which is disposed inside the valve body,

the method of manufacturing a piezoelectric valve is characterized in that,

silicone is supplied to the surface of the laminated piezoelectric element integrated with the actuator, and the surface of the laminated piezoelectric element is covered with the silicone.

7. The piezoelectric valve manufacturing method according to claim 6,

silicone is supplied to the surface of the laminated piezoelectric element integrated with the actuator, and the surface of the laminated piezoelectric element is covered with the silicone filled between a pair of projecting strips located on both sides of the laminated piezoelectric element in the longitudinal direction with a gap therebetween.

8. The piezoelectric valve manufacturing method according to claim 7,

the piezoelectric valve further includes a plate disposed inside the valve body,

the driver is fixed on the plate and is arranged in the valve main body together with the plate,

a pair of projecting pieces are provided on the surface of the plate, and when the actuator is fixed to the plate, the pair of projecting pieces are located on both sides in the longitudinal direction of the multilayer piezoelectric element with a gap therebetween,

the laminated piezoelectric element is integrated with the actuator, the actuator is fixed to the plate, silicone is supplied to the surface of the laminated piezoelectric element, and the surface of the laminated piezoelectric element is covered with the silicone filled between the pair of ridge pieces.

Technical Field

The present disclosure relates to a piezoelectric valve that opens and closes a valve by utilizing displacement of a laminated piezoelectric element, and a method for manufacturing the piezoelectric valve.

Background

Conventionally, there is known a piezoelectric valve which opens and closes a valve by displacement of a multilayer piezoelectric element and discharges a compressed gas (see patent document 1).

The piezoelectric valve described in patent document 1 utilizes the characteristics of a laminated piezoelectric element having excellent high-speed response performance, and includes a displacement amplification mechanism for amplifying a small displacement of the laminated piezoelectric element based on the principle of leverage.

In a piezoelectric valve, when a voltage is applied to a multilayer piezoelectric element, displacement of the multilayer piezoelectric element in an extension direction is transmitted to a valve element via a displacement amplification mechanism, and the valve element is rapidly moved to open the valve.

In the piezoelectric valve, when the application of voltage to the multilayer piezoelectric element is released, the restoring force of the multilayer piezoelectric element due to the restoration is transmitted to the valve element via the displacement amplification mechanism, and the valve element is rapidly brought into contact with the valve seat to close the valve.

In addition, the multilayer piezoelectric element has the following excellent advantages: low energy consumption accompanying the operation, and is suitable for high-speed operation, small size, and the like.

However, the multilayer piezoelectric element is structurally fragile due to the piezoelectric ceramic layer, and when the piezoelectric valve is used, the broken piece may be ejected together with the compressed gas.

Further, since the multilayer piezoelectric element is not suitable for a high humidity environment, when the piezoelectric valve is used in a high humidity environment, moisture may enter the multilayer piezoelectric element to shorten the life of the piezoelectric valve.

Therefore, the present inventors have proposed a method of covering the surface of a laminated piezoelectric element with a polyolefin resin (see patent document 2).

The piezoelectric valve described in patent document 2 uses a multilayer piezoelectric element covered with a polyolefin resin having characteristics of a small young's modulus and excellent flexibility, and having characteristics of a small moisture permeability and excellent water resistance. Therefore, when the piezoelectric valve is used, the broken piece of the multilayer piezoelectric element is not ejected together with the compressed gas. Further, even when used in a high humidity environment, there is no concern that moisture will penetrate into the multilayer piezoelectric element and shorten the life.

The surface of the multilayer piezoelectric element is thinly covered with a polyolefin resin, thereby preventing the discharge of a broken piece of the multilayer piezoelectric element. However, in order to prevent the reduction in insulation resistance of the multilayer piezoelectric element in a high-temperature and high-humidity environment, it is necessary to coat the surface of the multilayer piezoelectric element with a polyolefin resin to a certain extent in a thick manner. In this case, there is a fear that: the operation of the multilayer piezoelectric element is hindered, and the stroke is reduced or the operation cannot be performed accurately.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-124695

Patent document 2: japanese patent laid-open publication No. 2016-

Disclosure of Invention

Problems to be solved by the invention

Accordingly, an object of the present disclosure is to provide a piezoelectric valve and a method for manufacturing the piezoelectric valve, which can prevent a broken piece of a laminated piezoelectric element from being ejected together with a compressed gas during use, prevent moisture from entering the laminated piezoelectric element and shortening the life even when used in a high-humidity environment, and prevent the operation of the laminated piezoelectric element from being hindered and the stroke from being reduced or from being unable to perform an accurate operation.

Means for solving the problems

In order to achieve the above object, the present disclosure provides a piezoelectric valve that opens and closes a valve by displacement of a multilayer piezoelectric element, the piezoelectric valve including: a valve main body having a gas pressure chamber that receives compressed gas supplied from the outside; and an actuator which has a valve element, a multilayer piezoelectric element which generates a driving force required for the operation of the valve element as a displacement, and a displacement amplification mechanism which amplifies the displacement of the multilayer piezoelectric element and acts on the valve element, and which is disposed inside the valve body, wherein the surface of the multilayer piezoelectric element is covered with silicone in a state of being integrated with the actuator.

In the present disclosure, the surface of the multilayer piezoelectric element is preferably covered with silicone filled between a pair of projecting strips located on both sides of the multilayer piezoelectric element in the longitudinal direction with a gap therebetween.

In the present disclosure, it is preferable that the piezoelectric valve further includes a plate disposed inside the valve main body, the actuator is fixed to the plate, and is disposed inside the valve main body together with the plate, a pair of projecting pieces is provided on a surface of the plate, the pair of projecting pieces are located on both sides in a longitudinal direction of the laminated piezoelectric element with a gap therebetween when the actuator is fixed to the plate, and a surface of the laminated piezoelectric element is covered with silicone filled between the pair of projecting pieces in a state where the actuator is fixed to the plate.

In the present disclosure, the silicone is a low-viscosity silicone rubber, and a silicone rubber having a viscosity of 0.01Pa · s or more and 10.0Pa · s or less is preferably used, and a silicone rubber having a viscosity of 2.5Pa · s is more preferably used.

In addition, in view of workability, a one-component room temperature curing type silicone rubber is preferably used. For example, low-viscosity silicone rubber "KE-3475 (trade name)" manufactured by shin-Etsu chemical industries co.

In the present disclosure, it is preferable that the displacement amplifying mechanism is formed of a metal material, while the wiring for supplying power to the laminated piezoelectric element is formed by plate molding, and an electrode of the wiring exposed from the plate is covered with an insulating material in a state of being connected to a lead of the laminated piezoelectric element.

In the present disclosure, the displacement amplifying mechanism is preferably formed of a metal material, and the lead of the multilayer piezoelectric element is preferably disposed on an insulating film bonded to the surface of the displacement amplifying mechanism.

In order to achieve the above object, the present disclosure provides a method of manufacturing a piezoelectric valve that opens and closes a valve by displacement of a laminated piezoelectric element, the method including: a valve main body having a gas pressure chamber that receives compressed gas supplied from the outside; and an actuator which has a valve element, a multilayer piezoelectric element which generates a driving force required for the operation of the valve element as a displacement, and a displacement amplification mechanism which amplifies the displacement of the multilayer piezoelectric element and acts on the valve element, and which is disposed inside the valve body, wherein the method for manufacturing the piezoelectric valve is characterized in that silicone is supplied to the surface of the multilayer piezoelectric element integrated with the actuator, and the surface of the multilayer piezoelectric element is covered with the silicone.

In the present disclosure, it is preferable that silicone be supplied to the surface of the laminated piezoelectric element integrated with the actuator, and the surface of the laminated piezoelectric element be covered with silicone filled between a pair of ridge pieces located on both sides of the laminated piezoelectric element in the longitudinal direction with a gap therebetween.

In the present disclosure, it is preferable that the piezoelectric valve further includes a plate disposed inside the valve main body, the actuator is fixed to the plate, and is disposed inside the valve main body together with the plate, a pair of protruding pieces are provided on a surface of the plate, and when the actuator is fixed to the plate, the pair of protruding pieces are located on both sides in a longitudinal direction of the laminated piezoelectric element with a gap therebetween, the laminated piezoelectric element and the actuator are integrated, the actuator is fixed to the plate, silicone is then supplied to the surface of the laminated piezoelectric element, and the surface of the laminated piezoelectric element is covered with the silicone filled between the pair of protruding pieces.

Effects of the invention

Since the surface of the laminated piezoelectric element of the piezoelectric valve of the present disclosure is covered with silicone having excellent water resistance and water resistance, it is possible to prevent a broken piece of the laminated piezoelectric element from being ejected together with compressed gas during use, or to prevent moisture from entering the laminated piezoelectric element and shortening the life even when used in a high-humidity environment.

In addition, the surface of the piezoelectric multilayer element of the piezoelectric valve according to the present disclosure is covered with silicone having elasticity and a property of high compressibility compared to conventional polyolefin resins. Therefore, even when the surface of the multilayer piezoelectric element is covered with a thick silicone to some extent in order to prevent a decrease in insulation resistance in a high-temperature and high-humidity environment of the multilayer piezoelectric element, it is possible to prevent the operation of the multilayer piezoelectric element from being hindered and the stroke from being reduced or the multilayer piezoelectric element from being unable to perform accurate operation.

The piezoelectric valve according to the present disclosure can easily cover the entire peripheral surface of a laminated piezoelectric element with silicone if the laminated piezoelectric element is filled to the silicone-covered surface between a pair of projecting strips located on both sides of the laminated piezoelectric element in the longitudinal direction with a gap therebetween.

The piezoelectric valve according to the present disclosure further includes a plate disposed inside the valve body, the actuator being fixed to the plate and disposed inside the valve body together with the plate, and a pair of projecting strips provided on a surface of the plate and located on both sides in a longitudinal direction of the laminated piezoelectric element with a gap therebetween when the actuator is fixed to the plate, wherein the surface of the laminated piezoelectric element is covered with silicone filled between the pair of projecting strips in a state where the actuator is fixed to the plate, and the entire peripheral surface of the laminated piezoelectric element can be easily covered with the silicone.

In the method for manufacturing the piezoelectric valve according to the present disclosure, silicone is supplied to the surface of the laminated piezoelectric element integrated with the actuator, and the surface of the laminated piezoelectric element is covered with the silicone, so that even when the silicone overflows and adheres to a portion other than the surface of the laminated piezoelectric element, an assembly failure does not occur when the laminated piezoelectric element and the actuator are integrated.

In the method for manufacturing a piezoelectric valve according to the present disclosure, silicone is supplied to the surface of a laminated piezoelectric element integrated with an actuator, and the surface of the laminated piezoelectric element is covered with the silicone filled between a pair of projecting strips located on both sides of the laminated piezoelectric element in the longitudinal direction with a gap therebetween, so that the entire peripheral surface of the laminated piezoelectric element can be easily covered with the silicone.

The method for manufacturing a piezoelectric valve according to the present disclosure further includes a plate disposed inside the valve body, the actuator being fixed to the plate and disposed inside the valve body together with the plate, a pair of protruding pieces being provided on a surface of the plate, the pair of protruding pieces being located on both sides in a longitudinal direction of the laminated piezoelectric element with a gap therebetween when the actuator is fixed to the plate, and the laminated piezoelectric element being integrated with the actuator, and silicone being supplied to a surface of the laminated piezoelectric element after the actuator is fixed to the plate, and a surface of the laminated piezoelectric element being covered with the silicone filled between the pair of protruding pieces, even when the silicone overflows and adheres to a portion other than the surface of the laminated piezoelectric element, assembly failure when the actuator integrated with the laminated piezoelectric element is fixed to the plate does not occur.

In addition, in the method of manufacturing the piezoelectric valve according to the present disclosure, since the pair of projecting strips are provided on the surface of the plate and positioned on both sides in the longitudinal direction of the laminated piezoelectric element with a gap therebetween when the actuator is fixed to the plate, the entire peripheral surface of the laminated piezoelectric element can be easily covered with the silicone filled between the pair of projecting strips.

Drawings

Fig. 1 is a sectional view of a multilayer piezoelectric element.

Fig. 2 is a perspective view of a piezoelectric valve.

FIG. 3 is an exploded assembly view of a piezoelectric valve.

Fig. 4 is an explanatory diagram of the driver.

Fig. 5 is an explanatory diagram of a state where the actuator is fixed to the valve seat plate.

Fig. 6 is a cross-sectional view of the piezoelectric valve, and is an explanatory diagram of a state in which a valve seat plate is disposed inside a valve main body.

Fig. 7 is a plan view of an actuator provided in a piezoelectric valve according to an embodiment of the present disclosure.

Fig. 8 is a plan view of a state in which an actuator is fixed to a valve seat plate provided in a piezoelectric valve according to an embodiment of the present invention.

Fig. 9 is a sectional view a-a of fig. 8.

Fig. 10 is a graph showing the discharge pressure characteristics of air discharged from the piezoelectric valve according to the embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure are explained based on the drawings.

Fig. 1 is a cross-sectional view of a typical example of a multilayer piezoelectric element (hereinafter referred to as "piezoelectric element").

The piezoelectric element 1 shown in fig. 1 has a laminated body 4 in which piezoelectric ceramic layers 2 and internal electrode layers 3 are laminated alternately. The internal electrode layers 3 are exposed at the side surfaces of the multilayer body 4. The exposed side surfaces of the internal electrode layers 3 are covered with insulating layers 5 every other layer. Further, the laminate 4 has the external electrodes 6 covering the insulating layer 5 and electrically connected to the internal electrode layers 3 not covered with the insulating layer 5.

Fig. 2 is a perspective view of an example of the piezoelectric valve. FIG. 3 shows an exploded assembly view of the piezoelectric valve of FIG. 2. Fig. 4 shows an explanatory diagram of the driver. Fig. 5 is an explanatory view showing a state where the actuator is fixed to the valve seat plate. Fig. 6 is a cross-sectional view of the piezoelectric valve, showing an explanatory view of a state in which a valve seat plate is disposed in a valve main body.

The piezoelectric valve 10 shown in fig. 2 to 6 includes: a valve body 20; a valve seat plate 25 which is disposed inside the valve main body 20 and is fixed to the valve main body 20; and actuators 30 fixed to both surfaces of the valve seat plate 25 by screws.

The valve main body 20 is a housing having an open front surface, and includes a gas pressure chamber therein that receives a supply of compressed gas from an external compressed gas supply source (not shown).

Further, a connector portion 50 is provided on the front surface of the valve main body 20. A gas suction port 51 for sucking compressed gas into the valve main body 20 and a gas discharge port 52 for discharging compressed gas are opened in the front surface of the connector portion 50.

A wiring board 55 for supplying power to the piezoelectric element 32 is disposed between the valve main body 20 and the connector portion 50. At one end of the connector portion 50 and at a position lateral to the valve main body 20, a wiring connector 29 for supplying power to the piezoelectric element 32 via a wiring board 55 is disposed.

The valve seat plate 25 includes mounting portions for actuators 30 on both surfaces thereof, and includes a valve seat 26 against which a valve body 31 of the actuator 30, which will be described later, abuts. In addition, a cover member 28 that closes the opening of the housing is mounted on the front surface of the valve seat plate 25. The cap 28 is provided with a gas discharge passage that communicates from the valve seat surface of the valve seat 26 to a discharge port 52 that opens at the front surface of the connector portion 50. The cover 28 is provided with a gas suction passage communicating from a suction port 51 opened in the front surface of the connector portion 50 to the inside of the valve main body 20.

The valve seat plate 25 is molded from, for example, a synthetic resin material, and wiring from the wiring board 55 to the piezoelectric element 32 is molded.

As will be described later with reference to fig. 8, an electrode 58 of a wiring connected to a lead 57 of the piezoelectric element 32 is exposed at a rear position of the valve seat plate 25.

As shown in fig. 4, the driver 30 includes: a valve body 31 made of rubber, preferably a lubricating rubber; a piezoelectric element 32 that generates a driving force required for the operation of the valve body 31 as a displacement; and a displacement amplification mechanism 33 that amplifies the displacement of the piezoelectric element 32 and applies the amplified displacement to the valve body 31.

The piezoelectric element 32 can be the piezoelectric element shown in fig. 1. In addition, a resin-encased piezoelectric element in which the entire peripheral surface including the exposed side surfaces of the internal electrode layers 3 is thinly covered with an epoxy resin may be used as the piezoelectric element 32.

The displacement amplification mechanism 33 includes a displacement amplification unit 34 that amplifies the displacement of the piezoelectric element 32, and a displacement transmission unit 35 that transmits the displacement of the piezoelectric element 32 to the displacement amplification unit 34. The displacement amplification mechanisms 33 are arranged symmetrically with respect to an axis in the operating direction of the valve body 31, and herein with respect to a straight line (hereinafter referred to as "center line") connecting the valve body 31 and the longitudinal axis of the piezoelectric element 32.

The displacement transmission unit 35 includes a U-shaped base substrate 36 to which one end of the piezoelectric element 32 is bonded, and a cap member 37 to which the other end of the piezoelectric element 32 is bonded. The piezoelectric element 32 is disposed in a space of a U-shaped base substrate 36, and the displacement amplification mechanism 33 is disposed symmetrically about the longitudinal axis of the piezoelectric element 32.

Here, the piezoelectric element 32 is assembled in a space of the U-shaped base substrate 36 between the U-shaped bottom of the base substrate 36 and the cap member 37. By plastically deforming the U-shaped bottom of the base substrate 36, one end of the piezoelectric element 32 is joined to the U-shaped bottom of the base substrate 36, and the other end is joined to the cap member 37.

The displacement-enlarged portion 34 is composed of first and second displacement-enlarged portions 34a, 34b arranged symmetrically with respect to the center line.

The first displacement enlarged portion 34a has first and second hinges 39, 40, a first arm 41, and a first leaf spring 42. One end of the first hinge 39 is integral with the one-side front end of the U-shaped base substrate 36, and one end of the second hinge 40 is integral with the cap member 37. One end of a first leaf spring 42 is joined to an outer tip end portion of the first arm 41, and a side end portion of the spool 31 is joined to the other end of the first leaf spring 42.

On the other hand, the second expanded displacement portion 34b includes third and fourth hinges 43 and 44, a second arm 45, and a second leaf spring 46. One end of the third hinge 43 is integral with the other end of the U-shaped base substrate 36, and one end of the fourth hinge 44 is integral with the cap member 37. One end of a second leaf spring 46 is joined to an outer distal end portion of the second arm 45, and the other end of the second leaf spring 46 is joined to the other side end portion of the spool 31.

Here, the displacement amplification mechanism 33 can be integrally formed by punching a metal material such as a stainless material including an invar material, for example.

When the actuator 30 energizes the piezoelectric element 32 in the valve-closed state, the piezoelectric element 32 expands. The displacement accompanying the elongation of the piezoelectric element 32 is expanded by the principle of leverage in the displacement amplification mechanism 33 with the first and third hinges 39 and 43 as fulcrums, the second and fourth hinges 40 and 44 as points of force, and the outer distal ends of the first and second arms 41 and 45 as points of action, so that the outer distal ends of the first and second arms 41 and 45 are greatly displaced.

Then, the displacement of the outer tip portions of the first and second arms 41, 45 separates the valve body 31 from the valve seat 26 via the first and second leaf springs 42, 46, and opens the gas discharge path.

On the other hand, when the energization of the piezoelectric element 32 is released, the actuator 30 contracts the piezoelectric element 32, and the contraction causes the valve body 31 to be seated on the valve seat 26 via the displacement amplification mechanism 33, thereby closing the gas discharge path.

Fig. 7 is a plan view of an actuator provided in a piezoelectric valve according to an embodiment of the present disclosure.

In the actuator shown in fig. 7, in a state where the piezoelectric element 32 is integrated, the surface of the piezoelectric element 32, that is, at least the side surface of the piezoelectric element 32 where the internal electrode layers are exposed is covered with silicone 8.

The piezoelectric valve according to the embodiment of the present disclosure can be assembled integrally with the actuator 30, for example, by using a piezoelectric element 32 of the type shown in fig. 1, the surface of which is covered with silicone 8.

In the piezoelectric valve according to the embodiment of the present disclosure, the silicone 8 may be supplied to the surface of the piezoelectric element 32 integrated with the actuator 30 by a dispenser, a brush, or the like, and the surface of the piezoelectric element 32 may be covered with the silicone 8.

In the piezoelectric valve according to the embodiment of the present disclosure, when silicone 8 is supplied to the surface of the piezoelectric element 32 integrated with the actuator 30 and the surface of the piezoelectric element 32 is covered with the silicone 8, even when the silicone 8 is attached by protruding from the surface of the piezoelectric element 32, there is no fear of occurrence of an assembly failure when the piezoelectric element 32 and the actuator 30 are integrated.

The piezoelectric valve according to the embodiment of the present disclosure can be assembled by covering the surface with silicone 8 in a state where the piezoelectric element 32 and the actuator 30 are integrated, and fixing the actuator 30 to the valve seat plate.

Here, the piezoelectric element 32 may be such that at least the exposed side surfaces of the internal electrode layers are covered with the silicone 8, and preferably, all the side surfaces (entire peripheral surface) including the exposed side surfaces of the internal electrode layers are covered with the silicone 8.

When a resin-encased piezoelectric element whose entire circumferential surface is thinly covered with an epoxy resin is used as the piezoelectric element 32, the entire circumferential surface is preferably covered with silicone 8.

Fig. 8 is a plan view showing a state where an actuator is fixed to a valve seat plate provided in a piezoelectric valve according to an embodiment of the present disclosure. Fig. 9 shows a cross-sectional view a-a of fig. 8.

In the piezoelectric valve according to the embodiment of the present disclosure, a pair of projecting pieces 27 is provided on the surface of the valve seat plate 25 at the attachment portion of the actuator 30, and when the actuator 30 is fixed by a screw, the pair of projecting pieces 27 is located between the piezoelectric element 32 and the displacement transmission portion 35 with a gap therebetween and on both sides in the longitudinal direction (expansion and contraction direction) of the piezoelectric element 32.

As shown in fig. 9, the pair of projecting pieces 27 is formed to be higher than the surface of the piezoelectric element 32 of the actuator 30 fixed to the valve seat plate 25.

In the piezoelectric valve according to the embodiment of the present disclosure, after the piezoelectric element 32 in which the side surface of the actuator 30 shown in fig. 7 where the internal electrode layer is exposed is covered with the silicone 8 is fixed to the valve seat plate 25, the silicone 8 is supplied onto the surface of the piezoelectric element 32, whereby the entire peripheral surface of the piezoelectric element 32 can be covered with the silicone 8 filled between the pair of projecting pieces 27.

In the piezoelectric valve according to the embodiment of the present disclosure, the piezoelectric element 32 whose surface is not covered with the silicone 8 may be integrated with the actuator 30, the actuator 30 may be fixed to the valve seat plate 25, and then the silicone 8 may be supplied onto the surface of the piezoelectric element 32, whereby the entire circumferential surface of the piezoelectric element 32 may be covered with the silicone 8 filled between the pair of protruding pieces 27.

In the piezoelectric valve according to the embodiment of the present disclosure, since the pair of projecting pieces 27 located on both sides in the longitudinal direction of the piezoelectric element 32 with a gap therebetween is provided on the surface of the valve seat plate 25 when the actuator 30 is fixed to the valve seat plate 25, the entire circumferential surface can be easily covered with the silicone 8 filled between the pair of projecting pieces 27.

In the piezoelectric valve according to the embodiment of the present disclosure, if the actuator 30 is fixed to the valve seat plate 25 by integrating the piezoelectric element 32 whose surface is not covered with the silicone 8 with the actuator 30, and then the silicone 8 is supplied onto the surface of the piezoelectric element 32, and the entire peripheral surface of the piezoelectric element 32 is covered with the silicone 8 filled between the pair of projecting pieces 27, even when the silicone 8 overflows and adheres to a portion other than the surface of the piezoelectric element 32, there is no fear of occurrence of an assembly failure when the actuator 32 is fixed to the valve seat plate 25.

In the present disclosure, the silicone 8 is a low-viscosity silicone rubber, and a silicone rubber having a viscosity of 0.01Pa · s or more and 10.0Pa · s or less is preferably used, and a silicone rubber having a viscosity of 2.5Pa · s is more preferably used.

Further, in view of workability, it is preferable to use a one-pack room temperature curing type silicone rubber, and for example, a low viscosity silicone rubber "KE-3475 (trade name)" manufactured by shin-Etsu chemical Co., Ltd.

In fig. 8, an electrode 58 of a wiring molded to supply power to the piezoelectric element 32 is exposed at a position behind the valve seat plate 25, and is connected to a lead 57 of the piezoelectric element 32 by solder. The electrode 58 of the wiring is covered with an insulating material not shown in the figure in a state of being connected to the lead 57. As the insulating material, for example, an insulating resin material such as silicone can be used.

As shown in fig. 8, the actuator 30 has an insulating film 62 attached to a rear surface of the displacement transmission portion 35 of the displacement increasing mechanism 33.

In fig. 8, wiring from the wiring board 55 to the piezoelectric element 32 is molded in the valve seat plate 25 to which the actuator 30 is attached. The lead 57 of the piezoelectric element 32 is disposed on the insulating film 62 so as to prevent contact with the metal material constituting the displacement amplification mechanism 33 of the actuator 30. The lead 57 of the piezoelectric element 32 is connected to an electrode 58 of a wiring exposed at a rear position of the valve seat plate 25 by solder.

Here, as the insulating film 62, for example, a low moisture-permeable film can be used.

In the present disclosure, a low moisture-permeable film means that a material having a thickness of 1mm has a moisture permeability of 0.5g/m in an environment of 40 ℃ and 95% relative humidity²24hr or less.

As the low moisture-permeable film, a resin film made of a low moisture-permeable material, for example, a polyolefin resin film such as polyethylene, polypropylene, or polyethylene terephthalate, can be used. In addition, a resin film subjected to low moisture permeability processing such as coating with a low moisture permeability agent such as fluorine can be used as the low moisture permeability film.

The piezoelectric valve according to the embodiment of the present disclosure is provided with a pair of projecting pieces 27 on the surface of the valve seat plate 25. When the actuator 20 is directly attached to the valve main body 20, a pair of projecting pieces may be provided on the inner wall surface of the valve main body. In this case, after the actuator is fixed to the valve body, by supplying the silicone 8 onto the surface of the piezoelectric element, the entire peripheral surface of the piezoelectric element 32 can be covered with the silicone 8 filled between the pair of projecting strips 27.

In the piezoelectric valve of the present disclosure, since the surface of the piezoelectric element is covered with silicone having excellent water resistance and water resistance, it is possible to prevent the broken piece of the piezoelectric element from being ejected together with compressed gas during use, or to prevent moisture from entering the piezoelectric element and shortening the life even when used in a high-humidity environment.

In addition, the surface of the piezoelectric element of the piezoelectric valve of the present disclosure is covered with silicone which is more elastic than conventional polyolefin resins and has a property of high compressibility. Therefore, even when the surface of the piezoelectric element is covered with silicone to a certain extent in a thick manner in order to prevent a decrease in insulation resistance of the piezoelectric element in a high-temperature and high-humidity environment, it is possible to prevent the operation of the piezoelectric element from being hindered and the stroke from being reduced or to prevent the piezoelectric element from being operated accurately.

Fig. 10 is a graph showing discharge pressure characteristics of air discharged from the piezoelectric valve, and is a graph comparing a case where the surface of the piezoelectric element is covered with silicone and a case where the surface of the piezoelectric element is not covered with silicone. Further, the coating thickness when the surface of the piezoelectric element is coated with silicone is about 150 μm, and a decrease in insulation resistance under a high-temperature and high-humidity environment can be prevented.

The experiment was carried out based on the method described in [ example ] of Japanese patent application laid-open No. 2017-160973. The experimental conditions are as follows.

(1) Compressed air supply pressure: 0.15MPa (gauge pressure value under atmospheric pressure)

(2) Driving voltage: 72V

(3) Compressed air set flow: 39L/min

(4) Inputting a signal: first pre-pulse time t1 ═ 0.098ms

First rest time t2 ═ 0.08ms

Second pre-pulse time t3 ═ 0.6ms

Second rest time t4 ═ 0.03ms

Main pulse time t5 ═ 0.192ms

(energizing time of piezoelectric element: 1ms)

(5) Air ejection pressure detection position: 2mm from the front end of the gas discharge passage

In fig. 10, the broken line indicates the result of the piezoelectric valve in which the surface of the piezoelectric element is covered with silicone. In addition, the solid line indicates the result of the piezoelectric valve in which the surface of the piezoelectric element is not covered with silicone.

When the two are compared, the ejection pressure characteristics of the air are substantially the same, and it can be confirmed that, in the piezoelectric valve according to the embodiment of the present disclosure, even when the surface of the piezoelectric element is covered with silicone to a certain extent in a thick manner in order to prevent a decrease in the insulation resistance of the piezoelectric element in a high-temperature and high-humidity environment, the operation of the piezoelectric element is not hindered.

The present disclosure is not limited to the above-described embodiments, and the configuration thereof may be modified as appropriate without departing from the scope of the disclosure.

Industrial applicability

The piezoelectric valve according to the present disclosure is useful because it can prevent a broken piece of the laminated piezoelectric element from being ejected together with compressed gas when in use, can prevent moisture from entering the laminated piezoelectric element and shortening the life even when used in a high-humidity environment, and can prevent the operation of the laminated piezoelectric element from being hindered and reducing the stroke or from being unable to perform accurate operation.

Description of the symbols

1-laminated piezoelectric element, 2-ceramic layer, 3-internal electrode layer, 4-laminated body, 5-insulating layer, 6-external electrode, 7-lead wire, 8-silicone, 10-piezoelectric valve, 20-valve body, 25-valve seat plate, 26-valve seat, 27-protruding piece, 28-lid piece, 29-wiring connector, 30-actuator, 31-valve core, 32-laminated piezoelectric element, 33-displacement amplification mechanism, 34-displacement amplification portion, 35-displacement transmission portion, 36-base substrate, 37-cap piece, 39-first hinge, 40-second hinge, 41-first arm, 42-first plate spring, 43-third hinge, 44-fourth hinge, 45-second arm, 46-second plate spring, 50-connector portion, 51-gas intake port, 52-gas exhaust port, 55-wiring substrate, 57-lead wire, 58-electrode, 62-insulating film.