JPH0282662A - piezoelectric actuator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

(B) Prior Art Conventionally, as shown in FIG. 10, as one form of a piezoelectric actuator, a plunger 50 that moves in the axial direction within a casing 49, clamp members 51 and 52 that grip the plunger 50, and a clamp member are used. 51 and 52, and a stroke piezoelectric element 5556 that moves the plunger 50 in the axial direction in cooperation with the clamp piezoelectric elements 53, 54. In the figure, reference numeral 57 denotes a holder for supporting and fixing the clamping piezoelectric elements 53 and 54 and the stroke piezoelectric element 55 to the casing 49.

To briefly explain the operation of such a piezoelectric actuator, when the actuator drive button is pressed, the control device applies voltage to the clamping piezoelectric elements 53, 54 and the stroke piezoelectric elements 55, 56 according to the drive sequence program read out from the memory. is applied to clamp member 5.
By clamping the plunger 50 at 1.52 or moving it in the axial direction, the plunger 50 can be moved in a straight shape with a stroke on the μm order or subμ steel order.

(c) Problems to be Solved by the Invention However, such piezoelectric actuators still have the following problems.

That is, as shown in FIG. 11, in assembling the piezoelectric actuator, the clamp members 51, 52 are
In order to tightly contact the plunger 50 with a constant initial holding force, the plunger 50 is fitted so that an outward expanding force is applied to the plunger 50. Then, the piezoelectric plates 60 constituting each of the clamping piezoelectric elements 53 and 54 are sequentially bonded to the clamp members 51 and 52 with an adhesive.

However, once the clamp piezoelectric elements 53, 54 are bonded to the clamp members 51, 52 and hardened, the plunger 50 can no longer be inserted or removed;
It was impossible to measure and adjust the clamping force of the clamping members 51 and 52 alone.

Therefore, abrasion of the plunger 50 or abrasion of the clamp members 51, 52 during assembly or thereafter may cause malfunction of the piezoelectric actuator.
Even if an unbalance in the clamping force of 52 occurs, the clamping force cannot be adjusted and the piezoelectric actuator itself must be replaced, resulting in poor product yield and complicated maintenance. It had become.

(d) Means for Solving the Problems The present invention provides a plunger that can be moved back and forth in the axial direction within a casing, a piezoelectric element for stroke that moves the plunger back and forth, and a clamp member that is attached around the plunger, and the plunger is attached to a clamp member. A piezoelectric actuator is provided with a pair of piezoelectric clamping elements that can be pressed through the clamping member, and a clamping force adjustment wedge is interposed between the clamping member and the clamping piezoelectric element, and the clamping force is adjusted between the clamping member and the clamping force. It is an object of the present invention to provide a piezoelectric actuator characterized in that the adjusting wedge and the adjusting wedge are configured to be separable from each other.

(E) Actions and Effects With the above-described configuration, the present invention has the following actions and effects.

■The clamping force adjusting wedge is interposed between the clamping member and the piezoelectric clamping element, and the clamping force adjusting wedge is configured to be separable from each other.
The stroke piezoelectric element, the clamp member, the clamp piezoelectric element, and the clamping force adjustment wedge can be easily inserted into and removed from the plunger, and by operating the clamping force adjustment wedge, each clamp can be easily adjusted. The clamping force can be adjusted depending on the member,
Malfunctions caused by misalignment during assembly can be reliably prevented.

In addition, even if a difference occurs between the clamping forces of both clamping members due to wear of the clamping member or plunger during use, the clamping force can be easily adjusted by operating the clamping force adjustment member to ensure normal operation. It can be reinstated.

(f) Examples The present invention will now be explained in detail based on examples shown in the accompanying drawings.

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

As shown in the figure, the actuator A has a plunger d installed concentrically within a cylindrical actuator casing C having front and rear walls a and b and movable back and forth along the axis, and further has a plunger d mounted on the outer circumferential surface of the plunger d. A pair of clamping piezoelectric elements e each having an I on the clamping member concentrically above.

f and a stroke piezoelectric element g.

That is, in the illustrated embodiment, the clamping piezoelectric element e is disposed and supported on the left side of the holder H attached to the central part of the actuator casing C by the mounting pole h, while the clamping piezoelectric element f and The stroke piezoelectric element g is arranged and supported on the right side of the holder H.

The arrangement and support state of each of the piezoelectric elements e+Lg will be explained as follows.

First, to explain the arrangement and support state of the clamping piezoelectric element e, in FIG. is removably connected to the proximal end of the cylindrical clamp member extending in the direction of the front wall a.

In addition, the clamp part formed at the tip of the clamp member has a
has a holder H on its annular outer peripheral surface as shown in FIG.
An annular tapered surface t is formed whose outer diameter gradually decreases toward .

In addition, the overall structure of the clamp member according to FIG. 2 is shown, and as shown in the figure, a large number of slits sI are formed in the axial direction except for the female threaded part 1, so that it can be expanded and contracted in the radial direction. .

Further, as shown in FIG. 1, on the outer peripheral surface of the clamp member, a cylindrical clamp force adjusting wedge is disposed concentrically and removably and movably in the axial direction.

As shown in FIGS. 1 and 3, on the inner circumferential surface of the wedge portion 3 formed at the tip of the clamping force adjustment wedge W, there is a A tapered surface 1 which is slidably fitted into and closely attached to the provided tapered surface t1. is formed.

As shown in FIG. 3, the clamping force adjusting wedge has a large number of slits st except for its base, and can be expanded or contracted in the radial direction.

As shown in FIG. 1, the cylindrical clamping force adjustment wedge 1 has a piezoelectric element e formed by stacking a number of piezoelectric plates It is installed. In addition, the piezoelectric element e can also be formed by the - number of piezoelectric plates X.

On the other hand, on the outer peripheral surface of the cylindrical clamping force adjusting wedge 1, an annular spring holding bracket j is provided in a protruding manner at a position forming the rear part of the piezoelectric element e.

A clamping force adjusting spring m made of a compression coil spring is interposed between the rear surface of the spring holding bracket j and the front surface of the holder H. Note that other elastic bodies such as rubber can also be used, and in some cases, the elastic body can be omitted.

In this configuration, the clamping force adjusting wedge 1 is urged forward by the elastic force of the clamping force adjusting spring m, and the accompanying force is applied to the clamping member through the fitting between the tapered surface t1 and the tapered surface t2. An initial holding clamping force for clamping the plunger d can be applied to the clamping portion 1.

The initial holding clamping force can be easily adjusted by increasing or decreasing the length of the clamping force adjusting spring m by adjusting the amount of screwing into the female threaded part i of the holder H at the proximal end of the clamping member. can do.

Next, piezoelectric element g for stroke and piezoelectric element f for clamp
The arrangement and support state of the will be explained.

As shown in FIG. 1, the holder H has the base end of the stroke piezoelectric element g adhered to the side surface on the rear wall side of the casing, and the tip thereof extends toward the rear wall of the casing C. An annular support n for supporting the clamping piezoelectric element f is attached to the extended end.

In FIG. 1, reference numeral 0 indicates a female threaded portion provided in the axial direction on the inner periphery of the annular support n, and a cylindrical clamp member 1 extending in the direction of the rear wall of the casing C is attached to the female threaded portion 0. The base ends of the clamp member 1 are detachably connected to each other, and a clamping piezoelectric element f is provided on the outer circumferential surface of the clamp part l formed at the tip of the clamping member 1 in the same manner as the above-mentioned clamping piezoelectric element e. It is attached removably.

That is, the clamp part 11 formed at the tip of the clamp member 1 made of a cylindrical slit material has an annular taper on its annular outer peripheral surface that gradually reduces the outer diameter toward the holder H, as shown in FIG. It forms a surface E.

Further, as shown in FIG. 1, on the outer circumferential surface of the clamp member 1, a cylindrical clamping force adjustment wedge 2 with a slit is disposed concentrically and removably and movably in the axial direction. There is.

As shown in FIGS. 1 and 3, on the inner circumferential surface of the wedge part 0 formed at the tip of the clamping force adjusting wedge 2, there is provided a clamp part 1 of the clamp member 1 described above. Tapered surface L that is slidably fitted and tightly attached to the tapered surface provided on
4 is formed.

Further, as shown in FIG. 1, the cylindrical clamping force adjusting wedge 2 has a clamping piezoelectric element ``attached to the outer circumferential surface of its tip using adhesive.

On the other hand, on the outer peripheral surface of the cylindrical clamping force adjusting wedge 4, an annular spring retaining bracket P is protruded at a position forming the front part of the clamping piezoelectric element.

A clamping force adjusting spring q made of a compression coil spring is interposed between the rear surface of the spring holding bracket (p) and the front surface of the support tool n.

In this configuration, the clamping force adjusting wedge 6 is biased in the rearward direction by the elastic force of the clamping force adjusting spring q, and the rotating force is applied to the clamping member through the fitting between the tapered surface and the tapered surface t4. Clamp part 1 of 1. An initial holding clamping force can be applied to clamp the plunger d.

Then, this initial holding clamp force is applied to the clamp member 1
The length of the clamping force adjusting spring q can be easily adjusted by increasing or decreasing the length of the clamping force adjusting spring q by adjusting the amount by which the base end 12 of the holder 1 is screwed into the female threaded portion 0 of the holder 1.

Next, the operation and specific configuration of each piezoelectric element e, f, and H will be explained as follows.

That is, the piezoelectric elements e and r clamp the plunger d with a constant clamping force F in the non-energized state, and when a positive voltage is applied, they clamp the plunger d with a clamping force F+α, and a negative voltage is applied. This results in clamping with a clamping force F-α. Note that the clamping force is F-α>0. That is, even if a negative voltage is applied, the piezoelectric elements e and [ will clamp the plunger d with a constant clamping force.

On the other hand, when a positive voltage is applied to the piezoelectric element g, it extends in the axial direction on the plunger d, and when a negative voltage is applied, the piezoelectric element g contracts on the plunger d, shortening its total length in the axial direction. It turns out.

The plunger d then connects these three piezoelectric elements e and r.
, g can be moved in the axial direction by controlling the procedure of applying pressure to them by a control device C, which will be described later.

The piezoelectric elements e, f, and g connect a large number of piezoelectric plates X to a plunger d.
It is a cylindrical element formed by laminating in the axial direction. 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, r is a U-shaped or Y-shaped packing provided to improve the watertightness of the actuator A and has low sliding resistance.

In addition, FIG. 4 shows a piezoelectric actuator A having the above configuration.
The configuration of a control device C for controlling the is shown. As shown in the figure, the control device c includes a microprocessor R,
an input/output interface ST and the piezoelectric elements e, f,
It is composed of a memory U that stores a drive order program of H.

Next, the operation of the plunger d by the actuator A having such a configuration will be explained with reference to FIGS. 5 to 7.

When the actuator drive button V shown in FIG. 4 is pressed, the control device C applies a negative voltage to the piezoelectric element e as shown in FIG. The clamping force is reduced to F-α, and a positive voltage is applied to the piezoelectric element f to increase the clamping force to F+α to clamp the plunger d.

Next, as shown in FIG. 6, when a negative voltage is applied to the piezoelectric element g to make it contract, the piezoelectric element g moves in the direction of the arrow, and the piezoelectric element r moves into a plunger which is clamped by a clamping force F+α. d also moves in the direction of the arrow.

Thereafter, as shown in Fig. 7, a negative voltage is applied to the piezoelectric element f to reduce the clamping force to F-α, and a positive voltage is applied to the piezoelectric element e to increase the clamping force to F+α. to clamp plunger d. Then, when a positive voltage is applied to the piezoelectric element g to extend it, the piezoelectric element g moves in the direction of the arrow.

Then, by repeating the above operation, the plunger d
can be moved in a linear manner with a stroke on the μl order or subμm order.

In addition, in the above operation, one of the piezoelectric clamping elements ef is always in the clamping state, and when changing the gripping operation, the clamping operation of one piezoelectric clamping element is performed first, and after completion of the clamping operation, the clamping piezoelectric element ef of the other clamping element is clamped. The clamping force is released.

In the operation of such piezoelectric actuator A,
If there is an abnormality in the operation of piezoelectric actuator A due to a difference in the initial holding clamping force of l in the clamping member,
As mentioned above, attach 2,1□ to the proximal end of l to the clamp member.
holder [(female threaded part i, .

By adjusting the amount of screwing in, the initial holding clamping force can be easily adjusted independently.

In addition, if necessary, as shown in FIG.
The clamping force adjustment wedges W, , W, to which are glued can be easily separated, and then the clamping force can be adjusted and reassembled to the plunger d.

Furthermore, in this embodiment, a clamping force adjustment wedge, 6
works together with the clamping force adjustment springs m and q to force the plunger d and the clamp member onto the plunger d and the clamp member. 1 in the radial direction to automatically reduce the inner diameter by the amount of wear, so that a constant clamping force can be maintained at all times.

Therefore, from this point of view as well, reliable and accurate operation of the piezoelectric actuator can be expected.

Further, FIG. 9 shows an application example of the actuator A according to this embodiment, and is an example in which the piezoelectric actuator A is applied to an automatic opening/closing valve that functions as a hot water mixing faucet.

In FIG. 9, reference numeral 10 denotes a casing in the form of a cylindrical box, and the casing 10 has two exemplary flow passages 13 and 14 formed on its other side wall.

The − side flow paths 13 and 14 function as a water supply flow path and a hot water supply flow path for the hot and cold mixer faucet, and their outer open ends communicate with the water supply pipe 15 and the hot water supply pipe 16, respectively.

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

Further, a T-shaped other side flow path 20 with openings at both ends is formed on the other side wall of the casing IO.

The other side flow path 20 functions as a mixed water flow path of the hot and cold water mixing faucet, and its outer open end communicates with the mixed water pipe 21, while its inner bifurcated open end is connected to the compartment. It is connected to 17.18.

Furthermore, valve seats 22 and 23 are provided at the inner bifurcated opening of the T-shaped cylinder body 19, respectively, and the valve seats 22 and 23 are provided on the valve seats 22 and 23 by moving back and forth in the axial direction within the casing 10.
A valve body 2, 1.25, which is a diaphragm valve that comes into contact with and separates from 23 and opens and closes an inner bifurcated opening end, is disposed.

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

And each piezoelectric actuator A has its plunger d
The tips of the valve bodies 24 and 25 can freely come into contact with the rear parts of the valve bodies 24 and 25, and the valve bodies 24 and 25 can be opened and closed.

In addition, in FIG. 9, 30 is a temperature sensor provided in the other side flow path 20, which detects the temperature of the mixed water, feeds back the detected value to the control section as shown in FIG. Based on the detected value, the actuator A of the automatic opening/closing valve is operated by PID control or the like to perform appropriate temperature control.

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

That is, when the detected value from the temperature sensor 30 is fed to the control unit and the control unit separately operates both piezoelectric actuators A of the automatic opening/closing valve based on the detected value, the valve bodies 24 and 25 are set. Opens and closes depending on the temperature, - side flow path 1
The amount of water supplied and the amount of hot water flowing from 3.14 to the other side flow path 20 can be mixed at a constant mixing ratio.

In this operation, the valve bodies 24 and 25 are opened and closed by the piezoelectric actuator A, which has the above-described structure and has the above-described functions and effects, so that flow rate control and appropriate temperature control can be performed more precisely and reliably. It can be carried out.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional side view of a piezoelectric actuator according to the present invention, and FIGS. 2 and 3 are views of a clamping member and a clamping force adjustment wedge that constitute the same piezoelectric actuator. FIG. 4 is a conceptual diagram of the control device; FIGS. 5 to 7 are diagrams of the operating state of the piezoelectric actuator; FIG.・Explanatory diagram of separation work, No. 9 is a cross-sectional side view of an automatic opening/closing valve equipped with a piezoelectric actuator, FIG. In the figure, (A): Actuator (B): Piezoelectric element assembly (C): Control device (D): Automatic opening/closing valve C1: Wedge for clamping force adjustment (WZ): Wedge for clamping force adjustment (a): Front Wall (b): Rear wall (C): Casing (d) Nib plunger (k): Clamp member (1): Clamp member (cloudy): Clamp force adjustment spring (q): Clamp force adjustment spring

Claims (1)

[Claims] 1. A plunger (d) that can be moved back and forth in the axial direction within the casing (c), a piezoelectric element for stroke that moves the plunger (d) back and forth, and a piezoelectric element for stroke that moves the plunger (d) back and forth; In a piezoelectric actuator that includes a pair of clamping piezoelectric elements that can be pressed, a clamping force adjusting wedge is interposed between the clamping member and the clamping piezoelectric element, and the clamping force adjusting wedge is connected to the clamping member and the clamping force adjusting wedge. A piezoelectric actuator characterized by being configured so that they can be separated from each other.