JPH03149954A - Wobble motor - Google Patents

Abstract

PURPOSE:To realize the linear motion without use of any special motion transmission mechanism by forming at least one of an outer circumferential face of a rotor and an inner circumferential face of a stator to be a taper so that an outer diameter or an inner diameter of one end is larger with respect to other end. CONSTITUTION:A length LR of a rotor 12 is set larger than a length LS of a stator 10 and the shape of an outer circumferential face is tapered so that an outer diameter DR1 of one end is larger than an outer diameter DR2 of the other end. When a voltage is sequentially applied to each electrode of the stator 10, the rotor 12 is driven while being in rolling contact onto an inner face of the stator 10 with the action of an electrostatic force. In this case, at least one of the outer circumferential face of the rotor 12 and the inner circumferential face of the stator 10 is tapered to displace the rotor 12 in the axial direction of the stator 10 attended with the driving. Thus, linear motion is attained without using any special motion transmission mechanism by extracting the axial movement of the stator 10.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a wobble motor that is driven by applying electrostatic force between a stator and a rotor.

<Prior Art> Currently, electromagnetic motors are commonly used for various purposes. However, this type of motor has the disadvantage that when the motor diameter is reduced to about a few degrees, the volumetric efficiency of the electromagnetic force decreases, and the generated torque decreases.

Therefore, in recent years, highly efficient small motors that use electrostatic force as a driving force have been proposed, and in particular, wobble motors that have a mechanism that effectively generates torque are attracting attention.

This wobble motor, as shown in Figs. 3 and 4,
It has a structure in which a rotor 3 having an outer diameter smaller than the inner diameter of the inner hole 2 of a cylindrical stator l is provided, and a plurality of strip electrodes 4 are arranged on the inner surface of the stator 1 with an insulator 5 interposed therebetween. It is located. The rotor 3 is the inner hole 2 of the stator 1
By sequentially applying a voltage to each electrode 4 of the stator 1 and applying an electrostatic force between the stator 1 and the rotor 3, the rotor 3 rotates along its axis while moving along the inner surface of the stator 1. It is.

<Problems to be solved by the invention> However, since the conventional wobble motor only extracts rotational torque from the shaft rotation of the rotor 3, it is necessary to use a ball screw, etc., to linearly move an object using the motor output. It is necessary to convert rotational motion into linear motion using a motion transmission mechanism. However, when such a motion transmission mechanism is used, there is a problem in that the entire device becomes larger even though the motor itself is made smaller. Furthermore, since it is difficult in principle to obtain a sufficiently large torque with this type of motor that utilizes electrostatic force, there is also the problem that the use of this type of motion transmission mechanism causes a decrease in efficiency.

This invention was made in view of the above problem, and an object of the present invention is to provide a new wobble motor that can realize linear motion by itself without using a motion transmission mechanism by devising the shape of the rotor or stator. shall be.

<Means for Solving the Problems> The present invention provides a wobble motor in which a rotor having an outer diameter smaller than the inner diameter is provided in the inner hole of the stator and the rotor is driven by an electrostatic force acting between the stator and the rotor. At least one of the outer circumferential surface of the rotor and the inner circumferential surface of the stator is formed in a tapered shape such that the outer diameter or inner diameter of one end is larger than that of the other end.

<Operation> When a voltage is sequentially applied to each electrode of the stator, the rotor rotates around its axis while rolling on the inner surface of the stator due to the action of electrostatic force. In this case, since at least one of the outer circumferential surface of the rotor and the inner circumferential surface of the stator is tapered, the rotor is displaced in the axial direction of the stator as it rotates. Therefore, by extracting the movement of the stator in the axial direction, linear movement can be obtained without using any special motion transmission mechanism.

<Embodiment> FIG. 1 shows the configuration of a wobble motor according to an embodiment of the present invention.

The illustrated wobble motor includes a cylindrical stator 10 and a rotor 12 disposed in an inner hole 11 of the stator lO.
Although not shown, a plurality of electrodes and insulators are arranged alternately on the inner surface of the stator IO.

The length LII of the rotor 12 is longer than the length of the stator 10, and the shape of the outer peripheral surface is such that the outer diameter D□ at one end is the same as the outer diameter at the other end. It is formed into a tapered shape that makes it larger. This rotor 12 is connected to the inner hole 1 of the stator 10.
When the rotor 12 is inserted into and inscribed in the rotor 1, the rotor 12 is held in a state where its central axis 13 is inclined with respect to the cylindrical axis 14 of the stator 10 by a taper angle θ expressed by the following equation.

In this embodiment, the outer circumferential surface of the rotor 12 is tapered, and the inner hole 11 of the stator lO is straight with a constant inner diameter D8. However, as shown in FIG. Constant straight shape, inner hole 1 of stator lO
1 is the inner diameter D1 of one end. It may be formed into a tapered shape such that the inner diameter I)sz is larger than the inner diameter I)sz of the other end.

In the wobble motor shown in Fig. 1, the stator lO
When a voltage is sequentially applied to each electrode, an electrostatic force acts between the rotor 12 and the stator lO, and the rotor 12 is sequentially attracted to each electrode. As a result, the rotor 12 is transferred while being inscribed in the stator 10, and the rotor 12 itself rotates around the central shaft 13 in a direction opposite to the direction of transfer. In addition, since the outer circumferential surface of the rotor 12 is tapered, the rotor 12 moves along with the stator 100 and the cylindrical shaft 1.
The amount of movement X at this time when the rotor 12 is displaced in the direction of 4 is as follows, where 2 is the distance that the rotor 12 has rolled on the inner circumferential surface of the stator lO. However, when a voltage is applied to each electrode of the stator 1G for one revolution, 2=πDs.

By sequentially applying a voltage to each electrode of the stator 10 in this way, the rotor 12 moves linearly in the direction of the cylindrical shaft 14.
However, in this case, the difference in the outer diameter of the rotor 12 (D□-〇ml
) is set to be large and the taper angle θ is made large, the amount of movement per unit rotation can be increased and the operating speed can be increased. On the other hand, if the outer diameter difference (Dmt) of the rotor 12 is set small, the amount of movement per unit rotation becomes minute, and precise linear motion becomes possible.

Note that the illustrated wobble motor is not provided with a special mechanism for supporting the rotor 12, and the rotor 12 is moved to the stator 10 by the frictional force between the stator lO and the rotor 12.
It is held in the inner hole 11 of.

For example, when this wobble motor is used vertically, the rotor 12 is held by the frictional force represented by the product of the electrostatic force F acting between it and the stator 10 and the friction coefficient μ between the two, so the following formula is used: By satisfying the following relationship, the rotor 12 is held without a support mechanism.

M−g<F・mi...■ In the above formula, M is the mass of the rotor 12, and g is the acceleration of gravity.

Furthermore, if the load on the rotor 12, that is, the mass of the movable body driven by the rotor 12, is m, then if the following relationship is satisfied,
The rotor 12 can move a movable body.

(M+m)= g<F -//--...■Also, when using the wobble motor horizontally, the thrust of the wobble motor f
On the other hand, if the static frictional force mg-p of the movable body (where m is the mass of the movable body) satisfies the following relationship, the rotor 12 can move the movable body.

f>m-g-p... [F] <Effects of the Invention> As described above, the present invention provides at least one of the outer circumferential surface of the rotor and the inner circumferential surface of the stator with respect to the outer circumferential surface of the other end. Because it is formed into a tapered shape that increases the diameter or inner diameter,
The rotor can be displaced in the axial direction of the stator while being rotated, and linear motion can be realized without using a special motion transmission mechanism.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a wobble motor according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of another embodiment of the invention, FIG. 3 is a perspective view showing the appearance of a conventional example, and FIG. 4 is a vertical cross-sectional view of a conventional example. 10... Stator 11... Inner hole 12.
...rotor

Claims (1)

[Scope of Claims] A wobble motor in which a rotor having an outer diameter smaller than the inner diameter is arranged in an inner hole of the stator and drives the rotor by an electrostatic force acting between the stator and the rotor, wherein the outer circumferential surface of the rotor and the stator At least one of the inner circumferential surfaces of the wobble motor is formed in a tapered shape such that the outer diameter or inner diameter of the other end is larger than that of one end.