JPH0282665A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To perform clamping operation reliably for a long term by forming flat and annular insulating faces at the inner circumferential edges of the opposite side faces of the piezoelectric board in a clamping piezoelectric element thereby enlarging the area for gripping a plunger through a clamp. CONSTITUTION:In an actuator A, a piezoelectric element assembly B comprising three piezoelectric elements (e)-(g) is arranged concentrically on the outer circumferential face of a plunger (d). Clamps (k), (l) for clamping the plunger (d) are located at the inner diameter sections of the piezoelectric elements (e), (f). The piezoelectric board (y) of the clamping piezoelectric elements (e), (f) is not bevelled but formed, at the inner circumferential edges (z) of the opposite side faces, with flat and annular insulating faces (r). Since the clamps (k), (l) are enlarged or shrinked by means of the entire width L of the piezoelectric board (y), the width L and the area for clamping the plunger (d) are increased thus stabilizing the clamping force.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a piezoelectric actuator used for operating various devices.

(b) Conventional technology Conventionally, the 6-clamp piezoelectric element is expanded and contracted, and is composed of an axially movable granger, a clamp that grips the plunger, a piezoelectric element that operates the clamp, and a stroke piezoelectric element. There is a piezoelectric actuator that grips one plunger via a clamp and drives the plunger in the front-rear direction by expanding and contracting a piezoelectric element for stroke.

(c) Problems to be Solved by the Invention However, in order to improve insulation, the inner diameter portion of the piezoelectric plate (y) constituting the piezoelectric element for clamping is
As shown in Fig. 2, since the plunger was largely chamfered (Co), the width (Bi) and area for clamping the plunger were reduced, resulting in problems such as a decrease in clamping force.

(d) Means for Solving the Problems The present invention provides a piezoelectric actuator in which one plunger is clamped by a clamping piezoelectric element, and the same piezoelectric element is formed by bonding a large number of ring-shaped piezoelectric plates with conductive paste. , it is an object of the present invention to provide a piezoelectric actuator characterized in that flat and annular insulating surfaces are formed on the inner peripheral edges of both sides of the piezoelectric plate of the piezoelectric element for clamping.
(E) Functions and Effects With the configuration described above, the present invention provides the following functions and effects.

■A conductive paste is applied to both sides of the piezoelectric plate of the piezoelectric element for clamping, and an annular conductive paste-unapplied area is provided on the flat surface of the inner peripheral edge to form a slight annular insulating surface. The inner periphery of the piezoelectric plate, that is, the area where the plunger is gripped via the clamp, is configured to have a large area. Therefore, even if the plunger is repeatedly clamped, the inner periphery will not wear out, and will last for a long period of time. This allows for reliable rung operation.

(2) Also, since flat and annular insulation distances are provided on the inner peripheral edges of both sides of the piezoelectric plate, insulation from the plunger side is reliably maintained.

(F) Examples The present invention will be specifically described below based on examples shown in the attached drawings.

FIG. 1 shows the configuration of the piezoelectric actuator (8) according to this embodiment.

As shown, the actuator (A) is connected to the front and rear walls (a
Cylindrical actuator gauging (C
), and three piezoelectric elements (e) and (f) are mounted concentrically on the outer peripheral surface of one langier (d). (
It is constructed by arranging a piezoelectric element assembly tree (B) consisting of q).

In addition, in the illustrated embodiment, piezoelectric elements (e) (f) (
(1) is supported by a holder (H), the outer peripheral part of which was previously fixed to the end face of the front wall (a) with bolts (11°).

Then, the piezoelectric elements (e) (f) supported by the holder (H)
) has a clamp (k) (II) for clamping the 1-langeer (d) located on the inner diameter part, and a mounting collar (j) is located on the inner diameter part of the central piezoelectric element ((J). The bases (II) and (n) of the clamps (k) (J) are connected to the mounting collar.The tip of the clamp (k) (,1!) is divided into an appropriate number of parts by providing a slit. (p) is a piezoelectric element ((]) and (f)
This is a clamp plate installed between the

(q) is the substrate of the piezoelectric element (e), and the lead wire
(S) connects it to the electrode (s-1) of the piezoelectric element (e) 6 (1) is the substrate of the piezoelectric element ((II)), and the lead wire ((J) connects it to the piezoelectric element ((7)). It is connected to the electrode (u-1).

m is an insulating ring provided at the right end of the piezoelectric element (g), (W)
is the substrate of the piezoelectric element (f), which is connected to the electrode (X-1) of the piezoelectric element by a lead wire (x).

External lead wires are connected to each of the substrates (q), (t), and (v).

In addition, piezoelectric plates (y) of piezoelectric elements (e) and (f) for clamping
As shown in Figures 3 to 5, the inner peripheral edges (7) on both sides
It has a structure in which a flat, annular insulating surface (") is formed on the top of the piezoelectric plate without chamfering, so that the clamp (k) (j) can be expanded or contracted over the entire width (L) of the piezoelectric plate. It is.

Next, the operation and specific configuration of each piezoelectric element (a), (f), and (g) will be explained as follows.

That is, the piezoelectric element (elf) clamps one lange (d) with a constant clamping force F in the non-energized state, and by applying a positive voltage, it clamps with a clamping force F + α, By applying a negative voltage, clamping is performed with a clamping force F-α. In addition,
The clamping force is F-α≧0. That is, even when a negative voltage is applied, the piezoelectric elements (e) (f)
will clamp the plunger (d) with a constant clamping force.

On the other hand, when the piezoelectric element (g) is energized, the plunger (d)
The top of the plunger (d) extends in the axial direction, and in a non-energized state, the top of the plunger (d) contracts, shortening its total length in the axial direction.

The plunger (d) then connects these three piezoelectric elements (
e) ff) A control device f whose suppression application procedure to (g) will be described later.
By controlling according to (C), it is possible to move in the axial direction.

Piezoelectric elements (e) (f) ((1) is a large number of piezoelectric plates (y)
It is a cylindrical element formed by laminating in the axial direction of the plunger (d). Electrodes are provided at both ends of the cylinder, and it is configured to expand by applying a voltage to both ends.

Further, in FIG. 1, (Ill') is a U-shaped or Y-shaped packing with low sliding resistance, which is provided to improve the watertightness of the actuator (^).

In addition, FIG. 6 shows a piezoelectric actuator (
＾) shows the configuration of a control device (C) for controlling it. As shown in the figure, the control device (C) includes a microprocessor (R), an input/output interface (S) (T) consisting of an A/D, D/^ converter, etc., and the piezoelectric elements (e) (f). )(g) A memory ((1)) storing the driving order program, and an input interface ((1)).
Based on the input signal from the actuator drive button (31) that is input to the control device via the control device (S), a control signal is generated according to the program described above, and the control signal is transmitted to each piezoelectric element (e) via the output interface (T). (f) (g)
It is configured to connect with.

Note that the piezoelectric element piece can be made of, for example, piezoelectric ceramics, and examples of such piezoelectric ceramics include AB
PZT(Pb(Zr.

'I' i) 03) series, and PLZT (Pb, La
(Zr.

'T''1) Oa), P'r (Pb'riOa) type, or a three-component type based on PZT can be used.

Moreover, the piezoelectric elements (e), (f), and (g) can also be formed by laminating a large number of thin ring-shaped piezoelectric element pieces in the axial direction around the axis of the plunger (d).

In addition, in the configuration described in "2", the piezoelectric elements (e) (f) (q
) can have not only a circular cross section but also a rectangular cross section, for example, and can also be formed from divided pieces.

In addition, since the plunger (d) is clamped in large numbers by clamps (kHJ), it has a small linear expansion coefficient, high hardness, strength, creep resistance, and palm abrasion resistance, and has high processing accuracy. is desirable, for example,
A ceramic material may be considered.

Next, a piezoelectric actuator (8) having such a configuration
Regarding the operation of plunger (d) according to Figs. 7 to 9
This will be explained with reference to the figures.

When the actuator drive button (31) shown in FIG. 6 is actuated, the control device (C) applies a negative pulse to the piezoelectric element (e) as shown in FIG. 7 according to the drive sequence program read from the memory (11). Applying a pulse-like driving voltage to reduce the clamping force to the plunger (d) to F-α, and applying a positive pulse-like driving voltage to the piezoelectric element (f) to increase the clamping force to F+α to reduce the clamping force to the plunger (d) for one plunger. (d) Clamp.

Next, as shown in Fig. 8, when a negative pulse-like driving voltage is applied to the piezoelectric element ((+) and it is contracted, the piezoelectric element ((1)) moves in the direction of the arrow; The plunger (d), which the element (f) clamps with the clamper F1α, also moves in the direction of the arrow.

Thereafter, as shown in FIG. 9, a negative pulsed drive voltage is applied to the piezoelectric element (f) to reduce the clamping force to Fα, and a positive pulsed drive voltage is applied to the piezoelectric element (e). Increase the clamping force to F+α and press the plunger (d).
to be clamped. Then, when a positive pulse-like driving voltage is applied to the piezoelectric element (g) and the piezoelectric element (J) is stretched, the piezoelectric element (J) moves in the direction of the arrow.

Next, by repeating the above operation, 1 lunge (
d) can be moved in a linear manner with strokes on the μl order or subμl order.

Therefore, when such a piezoelectric actuator, 1 eta (^), is attached to a hot water mixing device (0), etc., which will be described later, the mixing valve can be opened and closed while finely adjusting its opening degree, and the temperature can be controlled appropriately. be able to.

In addition, Fig. 10 shows an actuator (A
) is an example in which a piezoelectric actuator (^) is applied to an automatic on-off valve (D) that functions as a hot water mixing faucet.

In FIG. 10, (10) is a gauging in the form of a cylindrical box, and the gauging (10) has two one-side channels (13014) formed on its open side wall.

The - side flow paths (13) and (14) function as the water supply flow path and the hot water supply flow path for the hot and cold mixer faucet, and their outer open ends are connected to the water supply pipe (15) and the hot water supply pipe (14), respectively.
6).

On the other hand, the inner open ends of the − side channels (13) and (14) are connected to partition walls (17) formed at both ends of the casing (10), respectively.
It communicates with (18).

Further, a T-shaped other side flow path (z0) with openings at both ends is formed on the other side wall of the gauging (10).

The other lPl flow path (z0) functions as a mixed water flow path of the hot and cold water mixer faucet, and the outer side [1
The end communicates with the mixing water pipe (z1), while the inner bifurcated open end communicates with the partition walls (17) and (18).

Furthermore, in the inner bifurcated opening of the T-shaped cylinder (19),
Valves W, (z2) (z3) are provided respectively,
The valve seat (z2N23) has a valve body (made of a diaphragm valve) that moves back and forth in the axial direction within the gauging (10) to come into contact with and separate from the valve seats (z2) and (z3) to open and close the inner bifurcated opening end.
z4) (z5) are provided.

Furthermore, piezoelectric actuators (^) are attached to both ends of the casing (10), respectively.

In each piezoelectric actuator (^), the tip of the plunger (d) can freely come into contact with the rear part of the valve body (z4) (z5), so that the valve body (z4) (z5) can be opened and closed.

In addition, in FIG. 10, (30) is the other side flow path (z0)
This is a temperature sensor installed inside the tank, which detects the temperature of the mixed water.
The detected value is fed back to the control unit as shown in Figure 6, and both actuators of the automatic opening/closing valve are controlled based on the detected value.
＾) is operated by PID control etc. to perform appropriate temperature control.

The operation of the automatic on-off valve fD) having such a configuration will be briefly explained as follows.

That is, when the detected value from the temperature sensor (30) is fed back to the control section and both piezoelectric actuators (^) of the automatic opening/closing valve (D) are actuated separately based on the detected value, the valve body (z4) (z5) opens and closes at the set opening degree, -
The amount of water supplied and the amount of hot water flowing from the side channels (13) and (14) to the other side channel (z0) can be mixed at a constant mixing ratio.

In this action, since the valve bodies (z4) and (z5) are actuated by the piezoelectric actuator (A), flow rate control can be performed more reliably, and appropriate temperature control can be performed more reliably. .

In addition, as mentioned above, the piezoelectric actuator has flat and annular insulating surfaces formed on the inner periphery of both sides of the piezoelectric plate of the piezoelectric element for clamping, so that the automatic opening/closing valve can operate reliably. Flow rate control and humidity control are performed reliably.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of a piezoelectric actuator according to the present invention. 2 and 3 are cross-sectional side views of essential parts of the present invention. FIG. 4 is a perspective view of the same. FIG. 5 is an enlarged sectional view of main parts. FIG. 6 is an explanatory diagram of the configuration of the control device. FIGS. 7 to 9 are explanatory views of the operating state of the actuator. FIG. 10 is a cross-sectional side view of an automatic on-off valve equipped with the above-mentioned actuator. FIG. 11 is a perspective view of a conventional type. FIG. 12 is an enlarged sectional view of the same. (82 Actuator (B: Piezoelectric element assembly (C: Control device (B): Automatic opening/closing valve (A: Front wall b: Rear wall C: Actuator casing d Nib plunger e: Piezoelectric element f): Piezoelectric element g): Piezoelectric Element: Clamp): Clamp: Insulating surface: Conductive paste: Piezoelectric plate: Inner periphery

Claims (1)

[Claims] 1) A plunger (
In a piezoelectric actuator formed by clamping the same piezoelectric elements (e) and (f) and bonding a large number of ring-shaped piezoelectric plates (y) with conductive paste (P), the piezoelectric element for clamping (e ) (f) A flat and annular insulating surface (r
) is formed.