JPH02142362A - Actuator - Google Patents

Abstract

PURPOSE:To improve endurability and available efficiency by arranging a slanting plate between a casing and a disc and by oscillatingly swinging the slanting plate. CONSTITUTION:A driving disc 2 is provided on a rotating shaft 1. Opposite the disc 2 a fixed casing 3 is provided. Between the disk 2 and the casing 3 a slanting plate 4 is arranged and between this diagonal plate 4 and the casing 3 a piezoelectric element 5 is arranged. The conical surface 41 of the slanting plate 4 comes into contact with the disc 2, while the above rotating shaft 1 is supported by a bearing 6. This bearing 6 can slide freely and a spring 8 is provided between the bearing 6 and an adjusting nut 7. By rotating this nut 7, the contact pressure of the slanting plate 4 to the disc 2 can be adjusted. Thus, if the voltage is applied to the piezoelectric element 5, the rotating shaft 1 is rotated through the slanting plate 4 and the disc 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an actuator that converts the deformation of a piezoelectric element into rotational force and extracts it. The present invention relates to an actuator that converts dynamic rotation into dynamic rotation and extracts it as output rotation.

(Prior art) Ultrasonic actuators that utilize the expansion and contraction of piezoelectric elements to generate rotational force are small, lightweight, and have high torque.
Since the inertial force is small, it is used as a driving source for various aerodynamic control devices.

An example of a conventionally known ultrasonic actuator will be described below with reference to FIG.

A driving disk 12 is provided on the rotating shaft 11, and the driving disk 1
A fixed casing 13 is provided opposite to 2. A piezoelectric element 1 is provided between the drive disk 12 and the fixed casing 13.
Four fixed disk-shaped elastic bodies 15 are disposed.

Its effect is as follows.

When a voltage is sequentially applied to the piezoelectric element 14 in the circumferential direction, a traveling wave is generated in the elastic body 15, and the traveling wave causes the driving disk 12 to
is rotated.

(Problems to be Solved by the Invention) However, the conventionally known ultrasonic actuator has the following problems.

In the known ultrasonic actuator, the elastic body causes resonance and undergoes large elastic deformation, and is further vibrated at a high frequency, resulting in significant fatigue of the material and shortening the lifespan of fatigue hemorrhoids.

Furthermore, although a resonant system is used to effectively utilize traveling waves, the resonant frequency is uniquely determined by the shape of the elastic body. Therefore, the rotational speed of the ultrasonic actuator is also fixed, resulting in a constant speed actuator.

In order to generate a traveling wave, standing waves with a phase difference of 90° are combined, but since only the portion corresponding to one of these standing waves can be used as driving force, the utilization efficiency as a traveling wave is up to 50%. Therefore, the efficiency as an ultrasonic actuator was not very high.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to improve the drawbacks of the conventionally known ultrasonic actuators, and to provide an ultrasonic actuator that is excellent in durability, has a large degree of freedom in selecting the rotational speed, and is highly efficient in utilizing the expansion and contraction motion of the piezoelectric element. It is about providing.

(Means for Solving the Problems) In order to achieve the above object, an actuator according to the present invention is configured as follows.

That is, in the first aspect of the present invention, a casing, a disc disposed opposite to the casing, a swash plate disposed between the casing and the disc, and one end of which is disposed on the swash plate. a piezoelectric element, the other end of which is fixed to the casing, and to which a voltage is applied so that the deformation sequentially moves in the circumferential direction;
of the casing or the disc, which causes no relative displacement between the swash plate and the disc by oscillating the swash plate by applying a voltage to the piezoelectric element. One of them is made non-rotatable and the other is made rotatable so that the output rotation is taken out from the rotatable side.

In another aspect of the present invention, either or both of the casing and the disc are provided so as to be able to approach and separate from each other, thereby making the contact pressure between the swash plate and the disc variable.

In still another aspect of the present invention, the disc and the swash plate are provided with teeth having different numbers of teeth that mesh with each other, and one swing of the swash plate causes the casing or the disc to shift by a phase difference corresponding to the difference in the number of teeth. I tried to get the output rotation from either one.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

Referring to the figure, a rotating shaft 1 is provided with a drive disk 2, either integrally or separately, and a fixed casing 3 is provided opposite the drive disk 2. Drive disk 2 and fixed casing 3
A swash plate 4 is arranged between. A piezoelectric element 5 is arranged between the swash plate 4 and the fixed casing 3. The piezoelectric element 5 has one end fixed to the swash plate 4 and the other end fixed to the fixed casing 3. The side of the swash plate 4 facing the drive disk 2 is a conical surface 41, and the conical surface 4. is in contact with the drive disk 2. The rotating shaft 1 passes through a fixed casing 3 and is rotatably supported by a bearing 6 provided between the fixed casing and the fixed casing. The bearing 6 is slidable on the rotating shaft 1 in the axial direction. An adjusting nut 7 is screwed into the end of the rotating shaft 1, and a spring 8 is provided between the adjusting nut 7 and the bearing 6. By rotating this adjustment point 7, the contact pressure of the swash plate 4 against the drive disk 2 can be adjusted. As can be seen from FIG. 2, there are a plurality of piezoelectric elements 5 in the circumferential direction, and in this embodiment, the number of piezoelectric elements 5 is 5A.
, 5B15C, 5D, 5a15b, 5c.

Eight pieces of 5d are installed.

The operation of the ultrasonic actuator according to an embodiment of the present invention configured as described above will be explained.

The state shown in FIG. 1 shows a state in which the piezoelectric element 5A is extended and the piezoelectric element 5a is contracted.

From this state, the voltage application is sequentially shifted in the circumferential direction so that the piezoelectric element 5B is expanded, the piezoelectric element 5b is contracted, the piezoelectric element 5C is further expanded, the piezoelectric element 5c is contracted, and then the piezoelectric The element 5D expands and the piezoelectric element 5d contracts. Then, the process returns to the expansion and contraction of the piezoelectric elements 5A and 5a.

In this way, when the voltage application completes one cycle, the swash plate 4 operates so that the top becomes oblique and swings and rotates.

The swash plate 4 does not rotate itself but simply swings at an inclination angle θ, but the conical surface 4 of the swash plate 4 does not rotate. Since the upper point is displaced at a predetermined circumferential speed, the conical surface 4I comes into contact with the drive disk 2 and drives it to rotate, so that the rotating disk 1
becomes rotating. The rotation mechanism in this case is known as a reduction mechanism using a swash plate gear (Japanese Unexamined Patent Publication No. 1986-60
-125443), and its reduction ratio is as follows.

That is, if the inclination angle of the swinging rotation is θ, the reduction ratio is 1/Sinθ.

Now, if the displacement amount of the piezoelectric element 5 is Δ, and the mounting radius of the piezoelectric element 5 is R, then ΔL is very small, so Sinθ=θ
In the end, the reduction ratio is 1/Sinθ=1/θ=1/(Δ
L/R)=R/ΔL.

The above is one embodiment of the present invention, and the present invention is not limited to the above embodiment.

For example, forming different numbers of teeth on the swash plate and the drive disk,
It also includes a configuration in which the phase shifts by the difference in the number of teeth during one oscillating rotation of the swash plate, and this shift is extracted as an output rotation.

Further, the fixed casing and the drive disk are relative, and the present invention also includes a structure in which the fixed casing is rotatable and the drive disk is fixed.

(Effects of the Invention) The effects of the present invention explained above are as follows.

Since the deformation of the elastic body is not utilized, the durability is independent of the fatigue life of the elastic body, and the durability is improved.

Furthermore, the rotation speed can be easily controlled by changing the amount of displacement of the piezoelectric element by changing the applied voltage, or by changing the rotation speed of the oscillating rotation.

Since it has the same characteristics as conventionally known ultrasonic actuators, it can be used in the same manner as conventionally known ultrasonic actuators.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an ultrasonic actuator showing an embodiment of the present invention, Fig. 12 is a front view showing the attachment of a piezoelectric element of the ultrasonic actuator of Fig. 1, and Fig. 3 is a sectional view of a known ultrasonic actuator. It is a diagram. 1: Rotating shaft 2: Drive disk 3: Fixed casing 4: Swash plate 4. : Conical surface 5: Piezoelectric element 6: Bearing 7: Nut 8 Nispring sub-agent Patent attorney Tsuji Sanbe (1 idiot) Fig. Fig. et al.

Claims (3)

[Claims] (1) A casing, a disc disposed opposite to the casing, and a swash plate disposed between the casing and the disc, one end of which is fixed to the swash plate and the other end of which is fixed to the swash plate. a piezoelectric element fixed to the casing and to which a voltage is applied so that the deformation sequentially moves in the circumferential direction; A relative displacement is produced between the swash plate and the disc, and either the casing or the disc is made non-rotatable, the other is rotatable, and output rotation is extracted from the rotatable side. actuator. (2) Either or both of the casing and the disc are provided so that they can approach and separate from each other, thereby making the contact pressure between the swash plate and the disc variable. Actuator as described. (3) The disk and the swash plate are provided with teeth with different numbers of teeth that mesh with each other, and one swing of the swash plate causes a phase difference corresponding to the difference in the number of teeth to be released from either the casing or the disk. 3. The actuator according to claim 1, wherein the actuator extracts output rotation.