JPS6188771A - Rotary drive device - Google Patents

Abstract

PURPOSE:To readily control an ultrafine rotating operation with a small and high torque by using piezoelectric elements of three types and utilizing the electrostrictive effects of them in special combination. CONSTITUTION:The outer and inner wheel 1, 2 and inner wheel inner rotary unit 3 of a rotary drive device are all freely rotatably composed concentrically, and a ball bearing 4 is provided between the wheels 1 and 2. Piezoelectric elements X-Z of three types of a piezoelectric element X mounted on the wheel 2, a piezoelectric element Y mounted on the wheel 3, and a piezoelectric element Z mounted to couple with the wheel 2 and the unit 3 are used. Thus, the element X controls to rotate by the frictional resistance for the relative rotation between the wheels 1 and 2, the element Y controls to rotate between the unit 3 and the wheel 1, and further the element Z restricts the rotary motion between the wheel 2 and the unit 3. When a voltage is sequentially applied to the elements X-Z to rotate the wheel 2 in the arbitrary steps in the rightward or leftward.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotational drive device using a piezoelectric element.

(Prior art and its problems) Conventionally, there are motors, rotary solenoids, etc. that are rotatably driven. The motor is an AC motor.

There are various types of motors such as DC motors and stepping motors, but none of them are small and have high torque, so they have to be used in combination with a reduction gear as required. Also, with a rotary type renoid (ON10 F of the output shaft
It can only perform two rotational operations (F), and is not suitable for applications such as motors that require control of minute rotational operations.

(Object of the invention) The object of the present invention is to eliminate such conventional drawbacks,
It is an object of the present invention to provide a rotary drive device that is small in size, generates high torque, and can easily control minute rotational movements.

(Structure of the Invention) According to the present invention, there is provided a rotating mechanism in which the inner ring is mounted so as to rotate inside the outer ring through means for reducing frictional resistance between the outer ring and the inner ring, which are circular in shape, and the inner ring. an inner rotating part that rotates freely on a concentric circle with respect to the outer ring; and an inner rotating part that is located between the outer ring and the inner ring and is attached to the inner ring, and generates mutual rotational movement on the surface facing the outer ring by expansion and contraction due to electrostrictive effects. a first piezoelectric element that is controlled by friction; and a first piezoelectric element that is installed between the outer ring and the inner ring inner rotating part and is attached to the inner ring inner rotating part and controls mutual rotational movement by an electrostrictive effect similarly to the first piezoelectric element. a second piezoelectric cord that is controlled by friction; and a second piezoelectric cord that is attached between the inner ring and the inner ring inner rotating part and controls the mutual rotational movement of the inner ring and the inner ring inner rotating part by expansion and contraction using an electrostrictive effect. A rotary drive device includes a piezoelectric element No. 3, and performs relative rotational motion between the outer ring and the inner ring by sequentially generating expansion and contraction due to the electrostrictive effect of the piezoelectric element No. 1.2.3. can get.

(Detailed description of the configuration) In the rotary drive device of the present invention, in a mechanism in which an outer ring and an inner ring rotate freely relative to each other, such as a ball bearing, three types of piezoelectric elements or pressure elements are used. Using a telescoping device or the like that magnifies and transforms the displacement of the effect, each electrostrictive effect is combined and utilized as follows. First, in the first piezoelectric element, mutual rotation between the outer ring and the inner ring is controlled by frictional resistance. Next, a second pressure 1 element is also provided inside the inner ring, and between the inner wheel rotating part that freely rotates like the hands of a clock on a concentric circle with respect to the outer ring and the inner ring, and the outer ring, Rotation control is performed using frictional resistance. Further, a third piezoelectric element is attached so as to restrict the mutual rotational movement of the inner ring and the inner ring inner rotating section.

Therefore, when voltages are sequentially applied to the piezoelectric elements 1.2.3, the inner ring rotates to the right or left with respect to the outer ring depending on the length of expansion and contraction due to the electrostrictive effect of the third piezoelectric element. .

Next, an explanation will be given with reference to drawings showing examples.

(Embodiment) FIG. 1 is an overview diagram showing a first embodiment of the rotary drive device of the present invention. The outer ring 1, the inner ring 2, and the inner ring rotating part 3 all rotate freely on concentric circles. Further, in this example, a ball bearing 4 is used as a means for reducing frictional resistance between the outer ring 1 and the inner ring 2. Therefore, as shown in the figure, there are three types of piezoelectric elements: a piezoelectric element Composed of pressure elements.

FIG. 2 is a top view of the rotary drive device shown in FIG. 1. The piezoelectric cords X and Y attached to the inner ring 2 and the inner-ring internal rotating part 3 are each lightly in contact with the outer ring 1, or are provided with a gap smaller than the displacement due to the electrostrictive effect of each piezoelectric element. Further, an inner ring inner rotating part 3 that freely rotates like the hands of a clock is connected to the inner ring 2 by a third piezoelectric element 2. The cross-sectional view of (G)-(G) at this time is shown in Fig. 3, and S)-[F
]) are shown in FIG. 4.

The sectional view taken along line (3)-(a) in Figure 3 shows how the outer ring 1 and the inner ring 2 are combined with the bearing 4 as a means of reducing frictional resistance, and how the outer ring 1 and the inner ring 2 are arranged concentrically like the hands of a clock with respect to the inner ring 2. The relationship between the inner ring rotating part 3, which is rotated freely, and the piezoelectric cord Y attached to the inner ring rotating part 3 and the outer ring 1 is shown. The [F])-03) sectional view in FIG. 4 shows the relationship between the piezoelectric element X attached to the inner ring 2 and the outside 1. At this time, each piezoelectric element X, Y must be in light contact with the outer ring 1, or a gap smaller than the displacement due to the electrostrictive effect of each piezoelectric cord X, Y must be provided in order to obtain a frictional force with the disconnection Jl. Yes.

FIG. 5 shows the basic operation of each piezoelectric element as a time chart. This is the state of voltages x, y, and z applied to each piezoelectric element X, Y, and ZK, and when the voltages x, y, and z applied to each piezoelectric element X, Y, and Z are ON, each piezoelectric element ,Y,
The explanation will be given assuming that Z generates an electrostrictive effect such that it expands and contracts when it is turned off. Then, as shown in FIG. 5(a), each pressure forming element X.

By applying a voltage X*yaZ to Y and Z at once, the inner ring 2 rotates clockwise with respect to the outer ring 1 in FIG. Conversely, each piezoelectric element
, Y, and ZK voltages X+7+z are sequentially applied to rotate the inner ring 2 to the left with respect to the outer ring 1 in FIG. 5(a) and 5), each piezoelectric element X, Y is turned continuously in units of one round P.

By applying the pressure zK; pressure X*y+Z, the inner ring 2 can be continuously rotated to the right or left by an arbitrary number of steps υ.

As a second embodiment, FIG. 6 shows a sectional view of a rotary drive device in which the bearing 4 shown in FIG. 3 in the first embodiment is integrated with the outer ring 1 and the inner ring 2. In this way, the shape and mounting method of each part can be easily changed without changing the basic configuration.

Three types of pressure 7 used in the first example as a third example
The first and second piezoelectric elements of the w element generate an electrostrictive effect by applying a voltage to each, and the more frictional force is obtained against the outer ring in fc4, the less likely it is to occur and the more stable the piezoelectric element becomes. rotation is obtained. Therefore, by including means for enlarging and converting the displacement of the piezoelectric element using the principle of leverage, a more stable and strong rotational force can be obtained. Further, by including a means for enlarging and converting the displacement in the third piezoelectric element, the rotation pitch can be increased, and a rotation drive device that rotates at a higher speed can be obtained.

Each of the elements X and Y described above as the fourth embodiment.

Stronger rotational force can be obtained by arranging a plurality of 2 and their attachment parts, for example, at 180 degrees or every 120 degrees of a circle around the rotation axis.

(Effects of the Invention) From the above, the rotary drive device of the present invention can easily be made small and compact, and can generate high torque and rotate. Furthermore, by controlling the piezoelectric elements in combination so that they operate in parallel or series, it is possible to easily generate high torque at a higher speed.

In addition, rotary drive devices used in robots, etc. often require a high-torque motor rather than a high-speed rotary motor, and a small-sized motor is very effective.

[Brief explanation of drawings]

FIG. 1 is an overview of the rotary drive device of the present invention, and FIG.
3 and 4 are cross-sectional views, and FIG. 5 is a diagram showing timing for control. FIG. 6 is a sectional view showing the second embodiment. In the figure, 1... Outer ring, 2... Inner ring. 3...Inner ring internal rotating part, 4...Ball bearing. X, Y, Z...indicate piezoelectric elements, respectively. Daitojin=shi P′zuru ・:(” Rod 5 Figure 1 (,) 1 (b)

Claims (1)

[Claims] A rotation mechanism in which the inner ring is attached to a circular outer ring and an inner ring so that the inner ring rotates inside the outer ring through means for reducing frictional resistance, and an inner ring that freely rotates on a concentric circle with respect to the inner ring. a first piezoelectric element that is located between an inner rotating part and the outer ring and the inner ring and is attached to the inner ring and controls mutual rotational movement by friction generated on a surface facing the outer ring by expansion and contraction due to an electrostrictive effect; a second piezoelectric element that is located between the outer ring and the inner ring inner rotating part and is attached to the inner ring inner rotating part and controls mutual rotational motion by friction due to an electrostrictive effect like the first piezoelectric element; a third piezoelectric element installed between the inner ring and the inner ring inner rotating part and controlling the mutual rotational movement of the inner ring and the inner ring inner rotating part by expansion and contraction due to an electrostrictive effect;
A rotary drive device characterized in that relative rotational movement is performed between the outer ring and the inner ring by sequentially causing expansion and contraction due to the electrostrictive effect of the piezoelectric elements of 2 and 3.