JP2800202B2 - Piezo actuator - Google Patents

Description

The present invention relates to a piezoelectric actuator used for operating various devices.

(B) Conventional technology Conventionally, as shown in FIG. 10, as one form of a piezoelectric actuator, a plunger 50 that moves in a casing 49 in an axial direction and clamp members 51 and 5 that grip the plunger 50 are provided.
2, the clamping piezoelectric elements 53, 54 for operating the clamp members 51, 52, and the stroke piezoelectric elements 55, 56 for moving the plunger 50 in the axial direction in cooperation with the clamping piezoelectric elements 53, 54. Some have been configured. In the figure, 5
7 is the piezoelectric element for clamping 53, 54 and the piezoelectric element for stroke 55
And a holder for supporting and fixing the above to the casing 49.

When the operation of the piezoelectric actuator is briefly described, when an actuator drive button is pressed,
The control device applies a voltage to the clamping piezoelectric elements 53, 54 and the stroke piezoelectric elements 55, 56 to cause the clamp members 51, 52 to clamp the plunger 50 in accordance with the driving sequence program read from the memory, By moving the plunger 50, the plunger 50 can be moved with a stroke on the order of μm or sub-μm in the shape of a worm.

(C) Problems to be solved by the invention However, such a piezoelectric actuator still has the following problems.

That is, as shown in FIG.
Each of 5, 56 is formed by bonding a large number of piezoelectric element pieces 60 in a laminated state.

In view of the small amount of displacement of the piezoelectric element pieces 60 in the axial direction of the plunger when a voltage is applied, the piezoelectric element piece 60 has a laminated structure to ensure a sufficient amount of displacement.

Incidentally, the stroke piezoelectric elements 55 and 56 require a large number of piezoelectric element pieces 60 and must apply a voltage to each of them, so that the energy efficiency deteriorates.

In addition, the laminated structure is complicated and complicated to manufacture, and increases the manufacturing cost.

An object of the present invention is to provide a piezoelectric actuator that can solve the above problems.

(D) Means for Solving the Problems The present invention provides a plunger that can move back and forth in the axial direction within an actuator casing, and a plunger disposed around the plunger.
A pair of left and right cylindrical clamping piezoelectric elements each configured to be capable of clamping the plunger via a cylindrical clamping member, and disposed around the plunger, and positioned between the pair of left and right clamping piezoelectric elements. A cylindrical piezoelectric element for moving the plunger forward and backward, wherein a donut-shaped flexible member connected to each clamp member is provided on both end surfaces of the cylindrical piezoelectric element for stroke. The inner surface of each of the flexible members is adhered to each other, and a retainer having the outer surface of one of the flexible members fixed to the actuator casing is attached, and a stroke amplifying member is continuously provided on the outer surface of the other flexible member, A clamp member is connected to the holder and the stroke amplifying member, and a clamp piezoelectric element is mounted on the outer peripheral surface of the clamp member. Chosuru is to St. provide a piezoelectric actuator.

(E) Function and Effect With the above-described configuration, the present invention has the following function and effect.

According to the present invention, an inner surface of a donut-shaped flexible member connected to each clamp member is adhered to both end surfaces of a cylindrical piezoelectric element for stroke, and an outer surface of one of the flexible members is attached to an actuator casing. A stroke amplifying member is provided on the outer surface of the other flexible member, and a clamp member is connected to each of the holder and the stroke amplifying member. Are mounted with a clamping piezoelectric element on the outer peripheral surface thereof.

Therefore, when a voltage is applied to the piezoelectric element for stroke,
Both sides of the piezoelectric element for stroke do not expand and contract because they are adhered to both flexible members, only the central part expands and contracts, and the piezoelectric element for stroke expands on both sides in a drum-shaped or concave on both sides. It deforms like a drum, and as a result, both flexible materials also deform like a bow, and based on the deformation, the outer surfaces of both flexible materials are displaced in the axial direction of the plunger, and the displacement is used to amplify the stroke. The inner surface of the member is amplified in the plunger axis direction and greatly displaced, and the clamp portion formed on the inner surface of the stroke amplifying member is also largely displaced in the plunger axial direction.

Thus, in the present invention, even if a piezoelectric element is formed by a single piezoelectric element piece or a laminate of a small number of piezoelectric element pieces,
The clamp can be largely displaced in the axial direction of the plunger by cooperation between the flexible member adhered to both surfaces of the piezoelectric element and the stroke amplifying member.

That is, even if the displacement generated by the stroke piezoelectric element composed of a single or a small number of piezoelectric element pieces is small, a sufficient displacement can be ensured, so that power consumption can be reduced and power can be saved.

Further, since the stroke piezoelectric element can be formed from a single or a small number of piezoelectric element pieces, the stroke piezoelectric element can be easily manufactured, and the manufacturing cost can be reduced.

(F) Embodiment Hereinafter, the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

FIG. 1 shows the overall configuration of a piezoelectric actuator A according to this embodiment.

As shown, the piezoelectric actuator A includes front and rear walls a,
plunger d concentrically and freely reciprocable along the axis in a cylindrical actuator casing c comprising
And a pair of clamp piezoelectric elements e and f each having a clamp member k and l, and a stroke piezoelectric element g are arranged concentrically on the outer peripheral surface of the plunger d. doing.

That is, in the illustrated embodiment, the clamping piezoelectric element e
Are disposed and supported on the left side of a holder H attached to the center of the actuator casing c, while the piezoelectric element f for clamping and the piezoelectric element g for stroke are disposed and supported on the right side of the holder H. ing. The holder H functions as a clamp attachment.

The arrangement and support of the piezoelectric elements e, f, and g will be described below.

First, the arrangement and support of the clamping piezoelectric element e will be described. In FIG. 1, a cylindrical slit having a vertically split slit extending in the direction of the front wall a of the casing c is provided on the inner surface of the holder H. Base k ₂ without slit of clamp member k
Are removably connected in a cantilever shape.

Further, the clamp portion k ₁ provided at the tip of the clamp member k in order to clamp the plunger d is the clamping member k
It provided from the proximal k ₂ to the position spaced apart.

Then, on the outer peripheral surface of the clamp portion k ₁ is attached with an adhesive piezoelectric elements e formed by laminating a single or small number of the piezoelectric plate.

Next, the arrangement and support of the piezoelectric element g for stroke and the piezoelectric element f for clamping will be described.

As shown in FIG. 1, on the right side of the holder H, a stroke piezoelectric element g formed by bonding a single or a small number of piezoelectric plates x in a laminated state is disposed. g has the inner surfaces of the flexible members j and m bonded to both side surfaces thereof using an adhesive.

One of the flexible members j has its outer surface held by a holder H.
And the other flexible member m is connected to an outer surface of a stroke amplifying member o made of a rigid material by a connecting bolt P.
Are linked by

Moreover, members for stroke amplification o is its inner surface, the vertical split slits provided a cylindrical base end without the slit of the clamp member l 1 ₂ which extends in the wall direction b of the casing c
Are removably connected in a cantilever shape.

Further, the clamp portion 1 ₁ which is provided at the distal end of the clamping member l in order to clamp the plunger d is the clamping member l
Provided from the proximal end 1 ₂ position spaced.

Then, on the outer peripheral surface of the clamp portion 1 ₁ is attached with an adhesive a piezoelectric element f formed by laminating a single or small number of the piezoelectric plate.

The clamping piezoelectric element f is a cylindrical element formed by laminating a single or a small number of piezoelectric plates x in the axial direction of the plunger d, similarly to the clamping piezoelectric element e. Is provided with an electrode, and is configured to be extended by applying a voltage to both ends thereof.

On the other hand, the stroke piezoelectric element g is also a smooth element formed by laminating a single or a small number of piezoelectric element pieces x in the axial direction of the plunger d.

Next, the operation and specific configuration of each of the piezoelectric elements e, f, and g will be described below.

That is, the clamping piezoelectric elements e and f clamp the plunger d with a constant clamping force F in a non-energized state,
When a positive voltage is applied, clamping is performed with a clamping force F + α, and when a negative voltage is applied, clamping is performed with a clamping force F−α. Note that the clamping force is F-α> 0. That is, even when a negative voltage is applied, the piezoelectric element for clamping is
e and f clamp the plunger d with a fixed clamping force.

On the other hand, the stroke piezoelectric element g is, in principle, in a state of being extended in the axial direction on the plunger d when a positive voltage is applied, and contracting on the plunger d in the state of being applied with a negative voltage, in the axial direction. Will be shortened.

However, in this embodiment, the piezoelectric element for stroke g
Since both sides of are bonded to both flexible members j, m,
Even when a forward / reverse voltage is applied to the stroke piezoelectric element g, both sides do not expand / contract, only the central part expands / contracts. Therefore, as shown in FIGS. Deforms into a bulging drum shape or a concave drum shape on both sides.

As a result, the two flexible members j, m also deform like a bow, and based on the deformation, the outer surfaces of the two flexible materials j, m are displaced in the axial direction of the plunger d, and Also, the stroke amplifying member o having an outer surface connected thereto is displaced.

By the way, the stroke amplifying member o is formed of a rigid member, and the distance between the outer surface and the inner surface is sufficiently ensured. will be displaced are amplified in the axial direction several times to several ten times, a piezoelectric element attached to the clamping portion k ₁ and the clamp portion k ₁ of the clamping member l formed on the inner surface of the stroke amplifying member o f is also greatly displaced in the plunger axis direction.

As described above, in the present embodiment, even if the stroke piezoelectric element g is formed by a single piezoelectric element piece x or a laminate of a small number of piezoelectric element pieces x, the flexible piezoelectric element bonded to both surfaces of the stroke piezoelectric element g sexual members j, the m and the stroke amplifying member o cooperation can be largely displaced clamping portion k ₁ and clamping piezoelectric element f in plunger axial direction.

That is, a sufficient displacement in the axial direction of the plunger can be ensured even if the displacement generated by the stroke piezoelectric element g composed of a single or a small number of piezoelectric element pieces x is small. Can be planned.

Further, since the stroke piezoelectric element g can be formed from a single or a small number of piezoelectric element pieces x, the stroke piezoelectric element g can be easily manufactured, and the manufacturing cost can be reduced.

Explaining other components in FIG. 1, r is a U-shaped or Y-shaped packing provided with a small sliding resistance for improving the watertightness of the piezoelectric actuator A.

FIG. 4 shows a configuration of a control device C for controlling the piezoelectric actuator A having the above configuration. As shown, the control device C includes a microprocessor R
, Input and output interfaces S, T, and the piezoelectric elements e, f, g
And a memory U which stores the driving order program.

Next, the operation of the plunger d by the actuator A having such a configuration will be described with reference to FIGS.

When the actuator drive button v shown in FIG. 4 is pressed,
According to the drive sequence program read from the memory U, the control device C holds the stroke piezoelectric element g in a negative voltage application state and applies a negative voltage to the clamp piezoelectric element e as shown in FIG. The clamp force on the plunger d is reduced to F-α, and a positive voltage is applied to the clamping piezoelectric element f to increase the clamp force to F + α to clamp the plunger d.

Next, as shown in FIG.
When a positive voltage is applied to the piezoelectric element for contraction, the piezoelectric element for stroke g moves in the direction of the arrow, and accordingly, the piezoelectric element f for clamping causes the plunger d to be clamped by the clamping force F + α.
Also move in the direction of the arrow.

Thereafter, as shown in FIG. 7, the clamping piezoelectric element f
To reduce the clamping force to F-α, and apply a positive voltage to the clamping piezoelectric element e to increase the clamping force to F + α to clamp the plunger d. When a negative voltage is applied to the piezoelectric element g for stroke and the piezoelectric element g is extended, the piezoelectric element g for stroke moves in the direction of the arrow.

Then, by repeating the above operation, the plunger d can be moved like a scale with a stroke on the order of μm or sub μm.

In the operation of the piezoelectric actuator A, as described above, the displacement in the axial direction of the plunger generated by the piezoelectric element g for stroke can be amplified, so that the voltage applied to the piezoelectric element g for stroke is made as small as possible. Power can be saved.

FIG. 8 shows an actuator A according to this embodiment.
Is an example in which a piezoelectric actuator A according to an automatic on-off valve D functioning as a hot and cold water mixing tap is applied.

In FIG. 8, reference numeral 10 denotes a casing that forms a cylindrical box, and the casing 10 has two one-side flow paths 13 and 14 formed on one side wall thereof.

The one-side flow paths 13 and 14 function as a water supply flow path and a hot water supply flow path of the hot and cold water mixing tap, and the outer open ends thereof communicate with a water supply pipe 15 and a hot water supply pipe 16, respectively.

On the other hand, the inner open ends of the one-side flow paths 13 and 14 communicate with partition walls 17 and 18 formed at both ends of the casing 10, respectively.

On the other side wall of the casing 10, a T-shaped other side flow path 20 having both ends opened is formed.

The other side flow path 20 functions as a mixed water flow path of a hot and cold water mixing tap, and the outer open end thereof communicates with the mixed water pipe 21, while the inner bifurcated open end thereof has a partition wall 17. , 18.

Further, valve seats 22 and 23 are provided in the inner forked opening of the T-shaped cylindrical body 19, respectively. , 23,
Valve bodies 24 and 25 each comprising a diaphragm valve for opening and closing the inner forked open end are provided.

Further, piezoelectric actuators A are attached to both ends of the casing 10, respectively.

Each of the piezoelectric actuators A is configured such that the tip of the plunger d can freely contact with the rear portions of the valve bodies 24 and 25.
25 can be opened and closed freely.

In FIG. 8, reference numeral 30 denotes a temperature sensor provided in the other side flow path 20, which detects the temperature of the mixed water and outputs the detected value to the fourth sensor.
This is fed back to the control device C as shown in the figure, and the control device C operates both actuators A of the automatic opening / closing valve D based on the detected value by PID control or the like to perform appropriate temperature control.

Then, the operation of the automatic on-off valve D having such a configuration is
Briefly, it is as follows.

That is, when the detection value from the temperature sensor 30 is fed back to the control unit and the two piezoelectric actuators A of the automatic on-off valve D are individually operated based on the detection value, the valve bodies 24 and 25 are set at the set temperature. , The water supply amount and the hot water supply amount flowing from the one side flow paths 13 and 14 to the other side flow path 20 can be mixed at a constant mixing ratio.

In this operation, the valve elements 24 and 25 have the above-described configuration, and are opened and closed by the piezoelectric actuator A having the above-described operations and effects.
Flow rate control and appropriate temperature control can be performed more precisely and reliably.

FIG. 9 shows the configuration of a piezoelectric actuator A according to another embodiment. As shown in FIG.
The present embodiment is characterized in that the piezoelectric actuator A in the above-described embodiment (FIGS. 1 to 7) is further provided with a clamping force adjusting function.

That is, the clamping member k, l, that on the annular outer peripheral surface to form an annular tapered surface t ₁ which gradually reduce the outer diameter toward the holder H as shown in Figure 9.

Further, the clamp member k, On an outer peripheral surface of the l, concentrically cylindrical piezoelectric element attached intermediate member W _1, W ₂ are arranged to be freely movable and axially removable.

The inner peripheral surfaces of the wedge portions W _1a and W _2a formed at the tips of the piezoelectric element mounting intermediate members W ₁ and W ₂ have tapered surfaces t ₁ provided on the outer peripheral surfaces of the clamp members k and l. slidably tapered surface t ₂ to be fitted in close contact is formed with.

Further, as shown in FIG. 9, the cylindrical piezoelectric element mounting intermediate members W ₁ , W ₂ are provided with clamping piezoelectric elements e, f formed by laminating a large number of piezoelectric plates x on their outer peripheral surfaces. It is mounted using an adhesive.

In the mounting of the clamping piezoelectric elements e and f, since the piezoelectric element mounting intermediate members W ₁ and W ₂ are made of an elastic material having a slit as described above, the inner diameters of the piezoelectric elements e and f are as small as possible. Intermediate member for mounting piezoelectric element even if it is small
By elastically reducing the diameter of W ₁ and W ₂ , the clamping piezoelectric elements e and f can be easily fitted to the outer peripheral surfaces of the piezoelectric element mounting intermediate members W ₁ and W ₂ , By applying an adhesive to the inner peripheral surfaces of the piezoelectric element mounting intermediate members W ₁ and W ₂ , the clamping piezoelectric elements e and f can be firmly bonded to the piezoelectric element mounting intermediate members W ₁ and W _2. it can.

Thus, since the inner diameter of the clamping piezoelectric elements e and f can be made as small as possible, the thickness of the adhesive can be made as small as possible, and a voltage is applied to the clamping piezoelectric elements e and f as described later. The clamping force generated when the voltage is applied can be transmitted to the clamping members k and l without being absorbed by the adhesive, and the plunger d can be clamped with a sufficient clamping force.

Further, as shown in FIG. 9, the clamping piezoelectric elements e and f on the outer peripheral surface of the cylindrical piezoelectric element mounting intermediate members W ₁ and W _2.
An annular spring holding bracket y ₁ , y ₂ is protrudingly provided at a position formed by the rear part of the spring.

Further, between the rear surfaces of the spring holding brackets y ₁ and y ₂ and the front surface of the holder H, clamping force adjusting springs z ₁ and z ₂ formed of compression coil springs are provided.

In such a configuration, the spring for adjusting the clamping force is provided.
The piezoelectric element mounting intermediate members W ₁ , W ₂ are urged forward by the elastic force of z ₁ , z ₂ , and the urging force is clamped through the engagement between the tapered surface t ₁ and the tapered surface t _2. Clamping member k for members k and l
To _1, l _1, it is possible to provide an initial retention clamping force for clamping the plunger d.

And, the initial holding clamp force is the clamping member.
k, clamping force adjustment spring by adjusting the internal thread portion i, screwing amount of p of proximal k _2, l ₂ of the holder H of the l
The length can be easily adjusted by increasing or decreasing the lengths of z ₁ and z ₂ .

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of a piezoelectric actuator according to the present invention, FIGS. 2 and 3 are operation explanatory diagrams when a voltage is applied to a stroke piezoelectric element, FIG. 4 is a conceptual configuration explanatory diagram of a control device, 5 to 7 are explanatory views of the operation state of the piezoelectric actuator, FIG. 8 is a sectional side view of an automatic on-off valve provided with the above-described piezoelectric actuator, and FIG. 9 is a sectional side view of a piezoelectric actuator according to another embodiment. FIG. 10 is a sectional side view of a conventional piezoelectric actuator. In the drawing, (A): piezoelectric actuator (C): control device (D): automatic opening / closing valve (d): plunger (e): piezoelectric element for clamping (f): piezoelectric element for clamping (g): piezoelectric for stroke Element (j): Flexible member (k): Clamp member (l): Clamp member (m): Flexible member (o): Stroke amplification member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keishi Horiuchi 2-1-1, Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Touchi Kikai Co., Ltd. (72) Takao Yoshida 2, Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka chome No. 1 TOTO within Co., Ltd. (56) reference Patent Sho 63-186071 (JP, a) JP Akira 60-219972 (JP, a) (58 ) investigated the field (Int.Cl. ⁶ H01L 41/083 H01L 41/09

Claims (1)

(57) [Claims] A plunger which can move back and forth in an axial direction in an actuator casing, and a plunger disposed around the plunger.
A pair of left and right cylindrical clamping piezoelectric elements each configured to be capable of clamping the plunger via a cylindrical clamping member, and disposed around the plunger, and positioned between the pair of left and right clamping piezoelectric elements. And a cylindrical piezoelectric element for stroke that moves the plunger forward and backward. The inner surface of each of the flexible members is bonded, the outer surface of one of the flexible members is attached to a holder fixed to the actuator casing, and a member for amplifying stroke is continuously provided on the outer surface of the other flexible member. The holder and the member for stroke amplification
A piezoelectric actuator, comprising a clamp member connected in series, and a clamping piezoelectric element mounted on an outer peripheral surface of the clamp member.