JPS6062879A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To reduce the size and the cost of a vibration wave motor by disposing a magnet at least at one of a stator and a rotor arranged in a thrust direction, thereby adapting for a hollow motor. CONSTITUTION:A cylindrical vibrator 20 is formed of a soft magnetic material. An electrostrictive element 21 is polarized, and bonded to the outer periphery of the vibrator 20. A rotor 22 is made of a plastic magnet. Part 23 of a rotor is made of a soft magnetic material, and bonded to the upside of a magnet rotor 22. A recess 25 is formed at the upper edges of the rotors 22. The rotors 22, 23 are attracted to the vibrator 20. The magnet rotor 22 is attracted and contacted under pressure with the vibrator 20. When an AC voltage is applied to the element 21, the rotors 22, 23 are driven, and rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a vibration wave motor driven by progressive vibration waves.

As disclosed in JP-A-52-29192, for example, a vibration wave motor converts the vibration motion generated when a frequency voltage such as alternating current or pulsating current is applied to an electrostrictive element into rotational motion or -dimensional motion. It is something that converts.

Compared to conventional electromagnetic motors, this motor does not require windings, so it has a smaller structure inside the cylinder, and has the advantage of being able to obtain high torque even when rotating at low speeds, as well as having a small moment of inertia.

Therefore, the recency is [1].

The vibration wave motor known from the above publications uses standing vibration waves generated in the vibrator to frictionally drive a moving body such as a rotor in one direction when it converts vibration motion into rotational motion. The vibrating body and the moving body come into frictional contact during the forward motion of vibration, and separate during the backward motion.

Therefore, the vibrating body and the movable body must have a structure in which they contact each other in a minute range, that is, a structure close to point or line contact, which results in poor friction drive efficiency.

A vibration wave motor has recently been improved in this respect, and the moving body can be moved to S4 by the progressive vibration waves generated in the vibrating body! ! There is something to drive it.

FIG. 1 shows a schematic diagram of the '12 section.

In the figure, 1 is an electrostrictive element made of, for example, PZT (lead zirconate titanate), and 2 is a vibrating body made of an elastic material, to which the electrostrictive element 1 is adhered. The vibrating body 2 is mounted together with the electrostrictive element 1 via a vibration absorber 4 (held on a stand 9. 3 is a rotating body, which is rotatably supported by a bearing 12 on a fixed shaft 10 via a bushing 14. The lower end of the fixed shaft 10 is attached to the base 9, and the upper end is screwed.A spring 16 is fitted to the upper end of the bushing 14 on the fixed shaft IO.
Nut 18 is screwed in through washer 17. As a result, the rotating body 3 is pressed against the vibrating body 2.

FIG. 2 is a side view showing the relationship between the electrostrictive element 1 and the vibrating body 2. FIG. The electrostrictive element l includes a plurality of elements 1al ・la2 ・1
a3*e* and lbl・1b2IIlb3... are glued together, and one group of electrostrictive elements 1al and la2
・la3 ..., the electrostrictive elements 1b of other groups, ・
1b2, 1b3, and Φ. are arranged shifted by the wavelength of the vibration wave.

Each electrostrictive element 1aI, 1a2, 1a3 in one group...
. . is the pitch of the repair wavelength, and the polarization properties of adjacent ones are opposite to each other. + and - in the figure indicate polarity. Each electrostrictive element 1b□ in the other group
Similarly, lb, lb3, . . . have a pitch of the same wavelength, and adjacent ones have opposite polarities. A single electrostrictive element having a size equal to the size of these electrostrictive elements arranged side by side may be formed and then polarized to the pitch described above. Electrodes for applying voltage are formed on both polarized surfaces of the electrostrictive element by vapor deposition, writing, or the like.

In the vibration wave motor having such a configuration, an AC voltage of V(, SinωL is applied to the electrostrictive elements 1aI *la7 *1a3 ela4 @116 in one group.The electrostrictive elements 1b, lb2 in the other group・An alternating current voltage of V. Cosωt is applied to lb3, 1b4, etc. Therefore, each electrostrictive element has a phase shift of 180° with respect to the polarization direction between adjacent elements, and a phase shift of 90° between the two groups. An alternating current voltage is applied to cause stretching vibration.This vibration is transmitted and the vibrating body 2 bends and vibrates according to the arrangement pitch of the electrostrictive elements 1.When the vibrating body 2 protrudes at every other electrostrictive element position, , the positions of every other electrostrictive element are retracted.On the other hand, as mentioned above, one group of electrostrictive elements is at a position shifted from the local wavelength with respect to the other group, and the phase of the bending vibration is shifted by 90 degrees. While the AC voltage is applied, vibrations are excited one after another and travel through the vibrating body 2 as progressive bending vibration waves.

The progress state of the wave at this time is shown in Figure 3 (a) (b) (c
) It is shown in (d). Assume that the progressive bending vibration wave now advances in the direction of arrow X. 0 is a stationary state j! The center plane of the vibrating body at point i is in the state shown by the chain line 6 in the vibrating state, and the stress due to bending is balanced on this neutral plane 6. Looking at the cross section 7 perpendicular to the neutral plane 6, no stress is applied at the intersection line 5 of these two planes, and the plane only vibrates. At the same time, the cross section 7 is pendulum vibrating left and right about the intersection line 5. In the state shown in FIG. 4A, a point P on the intersection line between the cross section 7 and the surface of the movable body side 1 of the vibrating body 2 is the right dead center of left-right vibration, and only the upward movement occurs. The pendulum vibration moves in the left direction (when the intersection line 5 is on the positive side of the wave (when it is on the -L side of the center plane 0)
Stress in the opposite direction to the wave's progress is applied, and the wave's negative side (rotation
(when it is on the left side) stress is applied in the right direction. That is, the same figure (
In a), when the intersection line 5' and cross section 7' are the former, stress F' is applied to point V; when the intersection line 5'' and cross section 7'' are the latter, stress F/ is applied to point P'. . The wave progresses, (b)
As shown in , when the intersection line 5 comes to the positive side of the wave, point P moves to the left and at the same time moves upward. In (c), point P only moves to the left at the top dead center of the F vibration. (d
) makes a leftward movement and a downward movement. The wave further advances, moving to the right and downward, moving to the right and in the J direction, and then returning to the state in (a). When this series of interlocking actions is combined, point P moves in a spheroidal motion. As shown in FIG. 2C, on the line where point P touches the rotating body 3, the rotating body 3 is frictionally driven in the X' force direction by the movement of the point P.

Since the rotating body 3 is frictionally driven in this way, it is necessary to press the rotating body 3 against the vibrating body 2. In the previous example, a spring 16 is placed in the center of the pushing mechanism. Therefore, it is difficult to create a hollow motor in which a driven body can be placed in the hollow part of the motor. It also becomes mechanically complex, which hinders miniaturization. It takes thousands of minutes to adjust the balance of the pressure applied to each position of the vibrating body.

The present invention was made in view of the above-mentioned facts, and it is an object of the present invention to provide a small and inexpensive vibration wave motor suitable for hollow motors.

In order to achieve this object, the present invention provides a stator having an electrostrictive element and a vibrating body, which is brought into pressure contact with the stator by a progressive vibration wave generated in the vibrating body by applying a frequency voltage to the electrostrictive element. In a vibration wave motor that frictionally drives a rotor, a magnet is disposed on at least one of the stator and the rotor arranged in the thrust direction to attract external force,
The vibration wave motor is characterized in that the rotor is brought into pressure contact with the stator.

The embodiments shown in the drawings will be described in detail below to clarify the structure of the present invention.

FIG. 4 is a perspective view showing an embodiment of a vibration wave motor to which 1 of the present invention is applied.

20 is a hollow disc type vibrating body (stator) made of a soft magnetic material such as iron. Reference numeral 21 denotes an electrostrictive element, which is subjected to polarization treatment based on the driving principle described above, and is in contact with the lower side of the vibrating body 2o. 22 is a rotating body (rotor),
Consists of plastic magnets. 23 is also a part of the rotating body, is made of soft magnetic material, and is bonded to the upper side of the rotating body 22. On the F side of the electrostrictive element 21, an iL pole (not shown) can be seen. Furthermore, the upper side is YR-coated with a vibration absorber, and the entire structure is housed in a housing.

A vertical cross-sectional view of the vibrating body 20# electrostrictive element 21 and the rotating bodies 22 and 23 is shown in FIG. Magnet 22 which is a rotating body
As for the polarity, N and S poles are arranged on the inner and outer peripheries. The rotating bodies 22 and 23 are attracted to the vibrating body (magnetic body) 20. The soft magnetic material 23 functions as a back yoke. The polar directions of the magnets 22 may be arranged alternately in the circumferential direction as shown in FIG. 6 (L view). Furthermore, the soft magnetic material 23 may be omitted.

In such a vibration wave motor, the magnet rotating body 22 is in suction pressure contact with the magnetic vibrating body 20, and when the above-mentioned AC voltage ratio is applied to the electrostrictive element 21, the rotating bodies 22 and 23 are driven and rotated. .

FIG. 7 is a partially cutaway side view of another embodiment. The rotating body 33 is made of a soft magnetic material, the vibrating body 32 is made of a non-magnetic material, and a magnet 34 is arranged below the electrostrictive cable 21, and a soft magnetic material 35 is arranged below the magnet 34, respectively. Therefore, the rotating body 33 is
It is attracted by the magnet 34 via the pulsating body 32 and the electrostrictive element 21, and is pressed against the vibrating body 32.

The tfJB diagram also shows another embodiment. Rotating body 37
The upper side is a soft magnetic material 37a, the upper side is a non-magnetic material 37b,
Glue the two together. In this embodiment as well, the magnet 34 is located below the electrostrictive element 21. Soft magnetic body 37a of rotating body 37
The portion is attracted by the magnet 34, and the non-magnetic body 37b is brought into pressure contact with the non-magnetic vibrating body 32. In addition, in the example shown in FIGS. 7 and 8, a vibration absorber may be arranged between the vibrating body 21 and the magnet 34.

FIG. 9 shows another embodiment. The vibrating body 45 and the rotating body 46 are in contact with each other on one inclined surface.

An electrostrictive layer R-21 is bonded to the upper side of the vibrating body 45.
On the north side thereof, a rotating body 46 in which a soft magnetic material 49 is bonded to a magnet 48 is arranged.

As explained below, in the vibration wave motor of the present invention, since the rotor and stator are brought into pressure contact by suction, it is easy to create a sound gap in the center, and the vibration wave motor is fitted into a hollow motor. Very small! It can be manufactured at low cost since no special adjustment of the pressure welding balance is required.

In addition, since the relative position of the rotor and stator is always located at the maximum suction force, the rotation center of the rotor is precisely automatically adjusted to the center of the stator.

[Brief explanation of drawings]

Figure 1 is a partially cutaway side view of a conventional vibration wave motor.
Figure r52 and Figure 3 are diagrams explaining the driving principle of a vibration wave motor, Figure 41Δ is a perspective view of a vibration wave motor to which the present invention is applied, Figure 5 is a partially enlarged sectional view thereof, and Figure 6 is a different implementation. FIGS. 7, 8 and 9, which are partially enlarged cross-sectional views of the example, are side views with a partially cut away side view of another embodiment. 20 is a vibrating body, 21 is an electrostrictive wood r., 22 is a magnet,
23 is a soft magnetic material. Patent applicant: Canon Co., Ltd. Figure 1 Figure 8 Figure 2

Claims (1)

[Claims] (1) A vibration wave of a stator having an electrostrictive element and a vibrating body, which frictionally drives a rotor that is in pressure contact with the stator by a progressive vibration wave generated in the vibrating body by applying a frequency voltage to the electrostrictive element. A vibration wave motor, characterized in that a magnet is disposed on at least one of the stator and the rotor arranged in the thrust direction to attract the other and press the rotor against the stator.