JPH01202180A - Fine distance stepless drive type actuator - Google Patents

Abstract

PURPOSE:To reduce a thrust force to be applied to a plunger by forming a reduced-diameter end reduced in a pressure bearing area at the end of the plunger. CONSTITUTION:A fine distance stepless drive type actuator A is composed by telescopically attaching a plunger (d) along an axis concentrically within a cylindrical actuator casing (c) having front and rear walls (a), (b), and arranging a piezoelectric element assembly B made of 4 piezoelectric elements (e)...(h) concentrically on the outer periphery. The plunger (d) can be moved in an axial direction by controlling the sequence of applying a voltage to the elements (e)...(h). A manual reset button (p) is attached to the center of the wall (b). In this case, the plunger (d) is formed at its end in a diameter-reduced end (q) in such a manner that the end face area (pressure receiving area) is remarkably reduced from that of the plunger (d). Accordingly, when it is used as a valve or the like, the actuator A can be accurately driven.

Description

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

(B) Conventional technology Conventionally, micro-distance stepless drive actuators such as piezoelectric actuators and stethoping grips have been used as a means to perform high-precision positioning and precisely control the operations of various devices and machines. It has been known.

(c) Problems to be solved by the invention However, when this actuator is applied,
Ensuring frictional force during clamping and manufacturing - From a technical standpoint, the diameter of the plunger must be greater than a certain level. Therefore, the pressure-receiving area at the tip of the plunger becomes considerably large, and as a result, the thrust force applied to the plunger in the axial direction cannot be ignored, making it impossible to accurately control the valve.

(d) Means for Solving the Problems The present invention provides a micro-distance stepless drive type actuator in which a plunger is installed in the actuator casing so that it can steplessly move back and forth in small steps along the axis. The present invention relates to a micro-distance stepless drive type actuator, which is characterized in that a diameter-reduced tip portion with a reduced pressure-receiving area is formed at the tip.

In this case, micro-distance stepless drive actuators include laminated piezoelectric actuators, piezoelectric bimorph actuators, stepping linear motors, piezoelectric linear motors, combinations of ultrasonic motors (rotary type) and rotating screws, and stepping motors (rotary type). ) and a rotating screw, etc.

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

In the present invention, since a reduced diameter tip with a reduced pressure receiving area is formed at the tip of the plunger, the thrust force applied to the plunger can be made as small as possible, and the plunger can be driven accurately.

Therefore, the driving of various control valves, devices, etc. can be precisely and precisely controlled.

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

FIG. 1 shows the configuration of a piezoelectric actuator A, which is one form of a minute distance stepless drive type 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,
Four piezoelectric elements e, f.

It is constructed by arranging a piezoelectric element assembly B consisting of g and h.

Furthermore, in the illustrated embodiment, the piezoelectric elements g and h are arranged in the center of the actuator casing a, and are fixed to the tip of a holder H whose base end is fixed to the front wall a.

Further, t+J is a cantilever-shaped elastic bridge whose base ends are fixed to the piezoelectric elements g and h and whose tips extend toward the front and rear walls a and b.

Piezoelectric actuators e and f are attached to the outer peripheral surfaces of the ends of the elastic bridges i and j, and I is fixed to the brake shoes on the inner peripheral surfaces thereof.

And this piezoelectric element e + f + g + h is
It is configured to retract when the power is turned off.

That is, when the piezoelectric elements e and f are energized, they extend and sharpen their inner diameters to release the clamp on the plunger d, and when they are not energized, they contract to reduce their inner diameters and clamp the plunger d. .

On the other hand, when the piezoelectric element g+11 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.

Then, the plunger d connects these four piezoelectric elements e+f
By controlling the voltage application procedure to +g+h by a control device C described later, it is possible to move in the axial direction.

As shown in FIGS. 1 and 2, the piezoelectric elements e, f, g, and h are cylindrical elements formed by laminating a large number of piezoelectric element pieces in the axial direction of the plunger d. electrodes are provided at the , and by applying a voltage to both ends,
It is configured to stretch.

In addition, piezoelectric ceramics can be used for the piezoelectric element piece, for example, and such piezoelectric ceramic Noxtsite is
BO3 is a ferroelectric material with a perovskite crystal structure, and P ZT (P b (Z r.

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

The piezoelectric element e + f + g + h 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 FIG. In this case, the direction of the applied voltage is changed by 90 degrees.

Further, in FIG. 1, m is a U-shaped or Y-shaped packing provided to improve the watertightness of the actuator A and has low sliding resistance.

In addition, in the above configuration, piezoelectric elements e, f, g, h are as follows:
It can have not only a circular cross section but also a rectangular cross section, for example, and can also be formed from divided pieces as shown in FIGS. 4 and 5.

In addition, since plunger d is clamped to the brake shoe many times by l, it has a small coefficient of linear expansion (high hardness, strength, creep resistance, and wear resistance, and has high processing accuracy). It is desirable to use a ceramic material, for example.

Furthermore, in this embodiment, the piezoelectric actuator A is
As shown in the figure, a manual return button p made of elastic rubber or the like is attached to the center of the rear wall, facing the plunger d. When the manual return button p is pressed, its front surface projects forward and comes into contact with the rear end of the plunger d, and the plunger d is connected to the piezoelectric element e,
It can be pushed forward and moved against the clamping force of f.

Therefore, if the plunger d stops with the valve etc. open during a power outage, etc., the manual return button p is immediately activated.
Press to close the valve completely to prevent spills, etc.

In addition, in this embodiment, the plunger d has a diameter-reduced tip q formed at its tip, and the tip q has an end surface area (pressure receiving area) that is significantly smaller than the cross-sectional area of the plunger d. There is.

Note that an elastic body is attached to the tip of the diameter-reduced tip q.

Therefore, when used in a valve or the like as described later, the pressure receiving area can be significantly reduced, so the thrust force applied to the plunger d can be minimized, and the thrust force applied to drive the plunger d can be minimized. Actuator A can be driven accurately.

Furthermore, if the stepped portion of the plunger d is brought into contact with the rear surface of the front wall when the plunger d has moved a certain distance forward (for example, at the fully closed position or a position slightly further advanced than that), FB such as a diaphragm of an on-off valve that can restrict further advancement of the plunger d and prevents the plunger from moving forward too much.
('Is can be reliably prevented.

Further, FIG. 6 shows the configuration of a control device C for controlling the piezoelectric actuator A.

As shown, the control device C includes a microprocessor r
, input/output interfaces s and t, and the piezoelectric element e
+ f + g + memory U that stores the drive sequence program of h.

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.

When the actuator drive button V shown in FIG. 6 is pressed, the control device C releases the voltage application to the piezoelectric element e and retracts the plunger d, as shown in FIG. 7, according to the drive order program read from the memory U. At the same time, a voltage is applied to the piezoelectric element f to expand the diameter of the plunger d.
Release the clamp.

Next, as shown in FIG. 8, when a voltage is applied to piezoelectric element g+11 to extend it, piezoelectric elements e and f move in the direction of the arrow, and along with this, plunger d, which piezoelectric element e clamps,
also moves in the direction of the arrow.

Thereafter, as shown in FIG. 9, when a voltage is applied to the piezoelectric element e to release the clamp of the stretching plunger d, and at the same time, the applied voltages to the piezoelectric elements g and h are released, the piezoelectric element g+Fl contracts in the direction of the arrow. Plunger d further moves in the direction of the arrow.

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.

In this embodiment, as described above, the plunger d of the piezoelectric actuator A has a reduced diameter tip q at its tip.
Since the pressure receiving area can be significantly reduced, the thrust force applied to the plunger d can be minimized, and the influence of the thrust force on the drive of the plunger d can be minimized, allowing accurate driving of the actuator A. becomes.

Moreover, FIG. 10 shows an example of application to the actuator 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. 10, 10 is a casing in the form of a cylindrical box, and the casing 10 has two flow passages 13 and 14 formed on its negative 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 opening ends of the − side flow paths 13 and 14 are, respectively,
It communicates with compartments 17.18 formed at both ends of the casing lO.

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

The other side flow path 20 functions as a mixing water flow path of a hot and cold water mixing faucet, and its outer open end communicates with the mixing water pipe 21, while its inner bifurcated open end is separated. It communicates with rooms 17 and 18.

Furthermore, valve seats 22 and 23 are provided in the inner bifurcated opening of the T-shaped cylinder 19, respectively, and the valve seats 22 and 23 are provided with valve seats 22 and 23 that move back and forth in the axial direction inside the casing lO. Valve bodies 24 and 25, which are diaphragm valves that come into contact with and separate from 22 and 23 and open and close inner bifurcated opening ends, are provided.

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, so that the valve bodies 24 and 25 can be opened and closed.

In addition, in FIG. 10, 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. Both actuators A of the automatic opening/closing valve based on the detected value
The system is operated by PTD control or the like to control the appropriate temperature.

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 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 to open. - 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 action, since the valve bodies 24 and 25 are operated by the piezoelectric actuator A,
Flow rate control can be performed more reliably, and appropriate temperature control can be performed more reliably.

In addition, in such control, as described above, since the plunger d of the piezoelectric actuator A has a diameter-reduced tip q at its tip, it is possible to minimize the influence of thrust force on the drive of the plunger d. This makes it possible to control the automatic opening/closing valve more accurately and reliably.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of a piezoelectric actuator which is one form of a minute distance stepless drive type actuator according to the present invention;
Figure 2 is a cross-sectional view taken along line 1-1 in Figure 1, Figures 3 to 5.
The figure is a cross-sectional view of a piezoelectric element according to another embodiment, FIG. 6 is a configuration explanatory diagram of a control device, FIGS. 7 to 9 are explanatory diagrams of operating states of an actuator, and FIG. It is a sectional side view of an automatic opening-and-closing valve. In the figure, A: Actuator B: Piezoelectric element assembly C: Control device D = Automatic opening/closing valve a: Front wall b; Rear wall C: Actuator casing d Ni plunger e: Piezoelectric element f: Piezoelectric element
g: Piezoelectric element h: Piezoelectric element q: Reduced diameter tip Patent applicant: Totoki Co., Ltd.

Claims (1)

[Claims] 1. In a micro-distance stepless drive type actuator in which a plunger (d) is installed in the actuator casing (c) so as to be able to steplessly move forward and backward in small steps along the axis, the plunger (d) A micro-distance stepless drive type actuator characterized by forming a reduced-diameter tip (q) with a reduced pressure receiving area at the tip.