JPH01173769A - Actuator - Google Patents

Abstract

PURPOSE:To prevent a trouble, which is caused by the runaway of a plunger, and so on by a method wherein an actuator actuates precisely various devices by the operations of 3 piezoelectric elements and the piezoelectric elements clamp the plunger in a state that a voltage is not applied. CONSTITUTION:Piezoelectric elements (e) and (f) are extended in a state that a current is not made to flow to clamp a plunger (d) and at the same time, shrink in a state of continuity to release the plunger (d). On the other hand, a piezoelectric element (g) is extended in a state that a current is not made to flow and is in a state extended in its axis direction on the plunger (d), and shrinks on the plunger (d) in a state that a current is made to flow and is shortened the whole length in its axis direction. Here, the elements (e) and (f) are respectively an element shaped like a ring formed by laminating concentrically a multitude of piezoelectric element pieces around the axis of the plunger (d), electrodes are mounted on the outsides of the rings like electrodes are mounted on the inner sides, which come into contact with the plunger (d), of the rings and when a voltage is applied, these rings shrink. The element (g) is a cylindrical element formed by laminating a multitude of piezoelectric element pieces in the axis direction of the plunger (d) and when a voltage is applied to both ends of the cylinder, the element shrinks.

Description

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

(B) Prior Art Conventionally, various types of actuators, such as mechanical actuators, electrical actuators, and fluid actuators, have been known as such actuators.

And by using such an actuator,
Various devices, machines, etc. can be made to perform desired operations automatically.

(c) Problems to be solved by the invention However, none of these conventional actuators could perform high-precision positioning and could not precisely control the operations of various devices and machines. .

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

(d) Means for Solving the Problems The present invention provides a plunger that is installed in the actuator casing so as to be movable forward and backward along the axis, and a radius of In addition to arranging multiple piezoelectric elements that expand and contract in the direction,
A piezoelectric element that expands and contracts in the axial direction is interposed between both piezoelectric elements,
In addition, the first piezoelectric element can be extended in the radial direction to clamp the plunger when no voltage is applied to the piezoelectric element, and the relative position between the predetermined part of the piezoelectric element and the actuator casing is kept constant. The present invention relates to an actuator characterized in that a holder is provided to maintain the actuator.

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

■The actuator moves the plunger forward and backward by activating three piezoelectric elements, so it can move the plunger forward and backward on the μm order or sub-μ order depending on the number of voltage applications, making it suitable for various devices and machines. etc. can be operated precisely.

■The actuator can move the plunger forward or backward on the μm order or subμ-〇 order, so
There is no need to interpose a speed reduction mechanism or the like between various devices, machines, and other driven objects, and the overall structure of various devices, machines, etc. can be made extremely compact.

(2) Since the piezoelectric element is configured to clamp the plunger when no voltage is applied, no power is consumed when the actuator is not in operation, resulting in a power saving effect. Further, even if the power supply is cut off while the actuator is operating, the piezoelectric element clamps the plunger, so it is possible to prevent the plunger from running out of control, and accidents caused by such runaway can be prevented.

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

FIG. 1 shows the structure of an actuator according to this embodiment.

As shown in the figure, the actuator A has a plunger d installed in a cylindrical actuator casing C having front and rear walls a and b so as to be movable back and forth concentrically and along the axis. Concentrically,
Three piezoelectric elements e.

It is constructed by arranging a piezoelectric element assembly B consisting of rlg.

The piezoelectric elements e, f, and g are configured to contract when the power is turned on.

That is, the piezoelectric elements e and f extend and clamp the plunger d when not energized, and contract and release the plunger d when energized. -On the other hand, the piezoelectric element g is
When the plunger is not energized, it extends in the axial direction on the plunger d, and when it is energized, the plunger d is contracted and its total length in the axial direction is shortened.

The plunger d then connects these three piezoelectric elements e and f.
, g can be appropriately controlled to move in the axial direction.

As shown in FIGS. 1 and 2, the piezoelectric elements e and r are ring-shaped elements formed by laminating a large number of piezoelectric element pieces concentrically around the axis of the plunger d, and the ring is attached to the plunger d. An electric bridge is attached to the outside as well as the inside in contact with d, and the ring is configured to contract when a voltage is applied.

Furthermore, as shown in Figs. 1 and 3, the piezoelectric element 0g is a cylindrical element formed by laminating a large number of piezoelectric element pieces in the axial direction of the plunger d, and has electric bridges at both ends of the cylinder. It is configured to contract by applying a voltage to both ends thereof.

Note that the piezoelectric element piece can be made of, for example, piezoelectric ceramic or clay, and such piezoelectric ceramics include A
PZT (Pb (Zr.

T 1) 03 series, or PLZT (Pb (Zr, Ti)
Ch), PT (PbTi03) system, or PZ
A three-component system based on T can be used.

Moreover, the piezoelectric elements e and f 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, as shown in the fourth panel. in this case,
The direction of voltage application will be changed by 90 degrees.

On the other hand, the piezoelectric element g can also be formed by stacking a large number of elongated thin-walled cylindrical piezoelectric element pieces concentrically around the plunger d, as shown in FIG.

Note that in this case as well, the direction of voltage application is changed by 90 degrees.

Furthermore, h is an elastic body such as a disc spring interposed between the rear end of the piezoelectric element g and the rear wall, and the piezoelectric element e.

The piezoelectric element assembly B is integrated by always elastically pressing f and g toward the front wall a.

Further, in FIG. 1, i and j are U seals provided to improve the watertightness of actuator A.

In the above configuration, the piezoelectric elements e, f, and g may have not only a circular cross section but also a rectangular cross section, for example, and may be formed from divided pieces as shown in FIGS. 5 and 6. You can also do that.

In addition, since the plunger d is clamped many times by the piezoelectric elements e and f9g, it has a small coefficient of linear expansion, and has high hardness, strength, creep resistance, and wear resistance.
Furthermore, it is desirable to have a material with high processing accuracy, and for example, a material made of a ceramic material can be considered.

Next, the movement of the plunger d by the actuator A having such a configuration will be explained with reference to FIGS. 7 to 9.

As shown in FIG. 7, the plunger d is clamped while leaving the piezoelectric element f as it is, and a voltage is applied to the piezoelectric element e to contract it, thereby releasing the plunger clamp.

Next, as shown in FIG. 8, when a voltage is applied to the piezoelectric element g to contract it, the piezoelectric element r moves in the direction of the arrow, and accordingly, the plunger d clamped by the piezoelectric element f also moves in the same direction. do.

Thereafter, as shown in FIG. 9, when a voltage is applied to the piezoelectric element f to release the clamp of the plunger d and at the same time the voltage applied to the piezoelectric element g is released, the piezoelectric element g extends in the direction of the arrow, and the piezoelectric element f also extends in the same direction.

After that, by repeating the above operation, plunger d
can be moved in a linear manner with a stroke on the μm order or sub-μm order, and various devices and machines can be operated precisely.

Further, FIG. 10 shows an application example of the actuator A according to this embodiment, and is an example in which the actuator is applied to an automatic opening/closing valve that functions as a hot water mixing faucet.

In FIG. 10, reference numeral 10 denotes a casing in the form of a cylindrical box, and the casing 10 has two cylindrical bodies 11 and 12 with openings at both ends protruding from the side wall thereof, and a single cylinder inside. It forms side channels 13,14.

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 frontage ends 13a and 14a are connected to the water supply pipe 15 and the hot water supply pipe 1, respectively.
It communicates with 6.

On the other hand, the inner opening ends 13b, 14 of the − side flow path 13.14
b communicate with compartments 17 and 18 formed at both ends of the casing 10, respectively.

Further, a T-shaped cylinder 19 with openings at both ends is protruded from the other side wall of the casing 10, and a T-shaped flow passage 20 on the other side is formed in the T-shaped cylinder 19. ing.

The other side flow path 20 functions as a mixed water flow path of a hot and cold water mixer faucet, and its outer open end 20a communicates with the mixed water pipe 21, while its inner bifurcated open end 20b , 20c communicate with compartment 17.18.

Furthermore, valve seats 22 and 23 are provided at the inner bifurcated openings of the T-shaped cylinder 19, respectively.
3, the valve seat 2 is moved back and forth in the axial direction within the casing 10.
Valve bodies 24 and 25, which are diaphragm valves that come into contact with and separate from 2 and 23 and open and close inner bifurcated opening ends 20b and 20c, are disposed.

Furthermore, actuators A are attached to both ends of the casing IO.

Each actuator A has a plunger d whose tip can come into contact with the rear part of the valve body 24.25.
, 25 can be opened and closed freely.

In addition, in FIG. 1O, 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 unit, and causes the control unit to automatically control the temperature based on the detected value. Both actuators A of the on-off valve are operated to control the temperature appropriately.

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 back to the control section and the control section operates both actuators A of the automatic opening/closing valve separately based on the detected value, the valve bodies 24 and 25 are opened at the set opening degree. Open and close the - side flow path 13.14
The amount of water supplied and the amount of hot water flowing into the other side channel 20 can be mixed at a constant mixing ratio.

In this operation, since the valve bodies 24 and 25 are operated by the actuator A, the flow rate control B can be performed more reliably, and the appropriate temperature control can be performed more reliably.

FIG. 11 shows another embodiment of the present invention.

In this figure, piezoelectric elements e, f, and g are held at the center of piezoelectric element g by a holding body to maintain their relative positions to actuator casing C.

t is a bridge portion that elastically connects the piezoelectric elements e and f with the piezoelectric element g, and U is the piezoelectric element e.

This lining material has frictional force and wear resistance suitable for restraining the plunger d by f.

Further, FIG. 12 shows another embodiment of the present invention applied to an automatic on-off valve.

As described above, the invention according to this embodiment has the following functions and effects.

■Actuator A has three piezoelectric elements e and r.

Since the plunger d is moved forward and backward by operating g, it is possible to move the plunger d forward and backward according to the number of voltage applications, in μ-order or sub-μl order. can be operated.

■Since the actuator A can advance and retreat the plunger d on the order of μm or sub-μm, there is no need to interpose a speed reduction mechanism etc. between the actuator A and driven objects such as various devices and machines. The overall structure of devices, machines, etc. can be made extremely compact.

■Piezoelectric element e when no voltage is applied.

Since f is configured to clamp plunger d, no power is consumed when actuator A is not in operation, resulting in a power saving effect. Furthermore, even if the power supply is cut off while actuator A is in operation, piezoelectric elements e and f clamp plunger d, which prevents runaway of plunger d and prevents accidents caused by such runaway. It can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of an actuator according to the present invention, FIGS. 2 and 3 are cross-sectional views taken along lines 1-1 and -■ in FIG. 1, and FIGS. 4 to 6 show other embodiments. A cross-sectional view of a piezoelectric element according to an example, FIGS. 7 to 9 are explanatory diagrams of the operating state of the actuator, FIG. 10 is a cross-sectional side view of an automatic opening/closing valve equipped with the above-mentioned actuator, and FIG. 11 is a cross-sectional view according to the present invention. FIG. 12 is a cross-sectional side view of another embodiment of the actuator, and FIG. 12 is a cross-sectional side view of an automatic on-off valve equipped with the same embodiment. A: Actuator B: Piezoelectric element assembly a: Front wall b: Rear wall C: Actuator casing d nib plunger e; Piezoelectric element f: Piezoelectric element
g: Piezoelectric element h: Holder Patent applicant: TOTO G9KI Co., Ltd.

Claims (1)

[Claims] 1. A plunger (d) is installed inside the actuator casing (c) so that it can move forward and backward along the axis, and a plunger (d) is expanded and contracted in the radial direction at a location on the outer peripheral surface of the plunger (d) that is spaced apart in the longitudinal direction of the plunger (d). piezoelectric element (e),
(f), and a piezoelectric element (g) that expands and contracts in the axial direction is interposed between the piezoelectric elements (e) and (f), and
At least the piezoelectric elements (e) and (f) are connected to the same piezoelectric element (
When no voltage is applied to e) and (f), the plunger (d) extends in the radial direction so that the plunger (d) can be clamped. ) to maintain a constant relative position of the holder (h
) is provided.