JPH07177769A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To provide a vibration wave motor which can form a travelling wave without using a piezoelectric element. CONSTITUTION:A vibration wave motor comprises a vibrator and a member, for example, a rotor 1 which is in contact with the vibrator. The vibrator has a field generating means comprising a plurality of drive coils 2 which generate one or a plurality of magnetic fields at the surface in contact with the rotor. The magnetic field generating means is driven with a rotating magnetic field which is almost matched with the natural frequency of the rotor 1 so that the rotor 1 is excited with a travelling wave to generate elliptical movement of the surface particles at the area of rotor 1 in contact with the vibrator. Thereby, the rotor 1 is rotated against the vibrator. A part of the rotor 1 corresponding to the area where the magnetic field excited by the vibrator is generated is attracted and deformed. When this area proceeds in the moving direction, the travelling wave is generated in the rotor 1 and the rotor 1 rotates when it receives a pressurizing force resulting from attraction force between the vibrator and rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration wave motor, and more particularly to a vibration wave motor for forming a traveling wave on a rotor by utilizing a change in magnetic attraction force excited on an exciter and rotating the rotor. Regarding

[0002]

2. Description of the Related Art As a motor utilizing vibration, an annular ultrasonic motor described in JP-A-59-201684 and JP-A-59-201685 is known.

The outline of this ultrasonic motor will be described with reference to FIG. 13. A piezoelectric element 4 provided in a part of a vibrator 4 is described.
The natural vibration of the oscillator 4 is excited by a, and an elliptic motion is generated on the contact surface with the rotor 3. Then, the rotor 3 rotates in contact with the upper part of the ellipse. 3a is an elastic member for adjusting the contact area between the vibrator 4 and the rotor 3, and 4b is a projection for enlarging the amplitude in the circumferential direction.

[0004]

Although the above ultrasonic motor has various advantages, the following problems have been pointed out.

Since a piezoelectric element is used, the cost is high.
Further, since the piezoelectric element uses lead, it has an effect on the environment.

Since the pressing force is always constant, it is difficult to operate at low speed. Also, the loss at the sliding portion is large at low speeds.

A bearing is required to support the axial pressure contact force.

Since the piezoelectric element is attached to the vibrator, the internal loss of the vibrator is large.

An object of the present invention is to solve the above problems and provide a vibration wave motor capable of forming a traveling wave without using a piezoelectric element.

[0010]

A structure of a vibration wave motor for achieving the object of the present invention includes a vibrating element and a member that comes into contact with the vibrating element, and the vibrating element has a contact surface with the member. Has a magnetic field generating means for generating one or a plurality of magnetic fields, and the elastic traveling wave is excited in the member by driving the magnetic field generating means at a cycle substantially matching the natural frequency of the member, Of the rotor, which is characterized by causing an elliptical motion in the surface particles at the contact portion with the exciter to move the exciter and the member relative to each other, and corresponding to a location where a magnetic field excited by the exciter is generated. The object is sucked and deformed, and a traveling wave is formed in the rotor by advancing in this direction in the moving direction, and the rotor rotates under the pressure applied by the suction force of the both.

[0011]

EXAMPLE FIG. 1 shows a first example.

In FIG. 1 (a), reference numeral 1 designates a metallic rotor made of a magnetic material such as iron and formed in an annular shape. In FIG. 1B, 2 is an exciter. 2a is an elastic member, 2b is an iron core, 2c is a coil, 2d is a substrate, and the iron core 2 is
In b, 6 kerfs are formed at equal pitch in the radial direction,
The coil 2c is wound around each of the convex portions in between. As shown in the figure (c), alternating currents i ₁ and i
_{When 2} and i _{3 respectively} flow, a magnetic flux is generated in the iron core 2b, a magnetic attraction force is generated on the upper surface of the exciter 2, and the rotor 1 and the exciter 2 are attracted to each other as shown in (d) of FIG. To be done. Figure 2 now
As shown on the (a) to (c) to (A) sides, the magnetic flux density B ₁
The currents i _{1 to} i ₃ are input with different temporal phases so that B ₃ to B ₃ are generated. Then, the magnetic attraction force has a shape as shown on the (B) side of (a) to (c) of FIG. 2, that is, f ₁ (t) = f ₁ '(1-cosωt) f ₂ (t) = f ₂ a distribution such as '{1-cos (ωt + 2 / 3π)} f 3 (t) = f 3' {1-cos (ωt + 4 / 3π)}. Where ω is the excitation angular frequency.

When the amplitude f ₁ ′ ≈f ₂ ′ ≈f ₃ ′, the magnetic attraction force is υ = ω / 2πλ (λ is the wavelength, λ = π
d / 2) (d is the center diameter of the iron core 2b).

Since the rotor 1 has a circular (true circle) ring shape shown in FIG. 3, it has four nodes, and an antinode portion between them has an eigenmode in which it vibrates in the out-of-plane direction. When the natural angular frequency of this mode is close to ω, a traveling wave having a natural mode shape is generated in the rotor corresponding to the magnetic attraction force.

FIGS. 4 and 5 are views showing this state, in which the rotor 1 and the exciter 2 are expanded in the circumferential direction and enlarged in the longitudinal direction. Figure 4 shows the second and fifth iron cores 2 from the left.
It is the moment when the suction force at b-2, 2b-5 becomes maximum, and the upper portion of the rotor 1 is bent downward, and the elastic member 2a is compressed. As the suction force progresses to the right side in the figure, the elastic traveling wave in the rotor 1 also moves to the right side accordingly, and the amplitude expands. When the excitation force due to the suction force is constant, the amplitude of the rotor saturates at a certain constant value. FIG. 5 is a diagram at that time. That is, the rotor 1
Is in contact with the elastic member of the exciter 2 at two places, the part between them,
That is, there is a gap between both ends and the center. Elastic member 2
a is compressed only at the contact portion due to the suction force.

At this time, the rotor 1 has a circumferential direction (horizontal direction in the drawing) substantially proportional to the distance from the neutral plane (dotted line).
Since the amplitude is generated, an elliptic motion is generated on the lower surface of the rotor 1 as in the conventional ultrasonic motor. At the position where the lower surface of the rotor 1 and the elastic member 2a come into contact, the point on the rotor 1 tries to move to the left, and as a result of being constrained by 2a, the rotor 1 moves in the right direction, that is, in the same direction as the traveling wave. Do it.

FIG. 6 shows a second embodiment. In this embodiment, the height of the neutral surface is increased and the circumferential amplitude is increased by providing the projection 1a on the lower surface of the rotor 1. This allows
When the axial amplitudes of the rotor are equal, the rotational speed of the rotor can be increased.

FIG. 7 shows a third embodiment. In this example,
A disk-shaped support plate 1b is fixed to the inside of the annular rotor 1, and an output shaft 1c is provided at the center of the support plate 1b.
It is configured to obtain the shaft output. The support plate 1b and the output shaft 1c are objects having rigidity and mass such that the output shaft 1c is hardly excited by the vibration of the rotor 1.

FIG. 8 shows a fourth embodiment. First mentioned above
In the embodiment, the coil 2c is wound around the lower part of the exciter 2 with the axial direction as the winding center, but in the present embodiment, the coil 2c is wound.
The coil 2c is arranged in the radial direction and the coil 2c is arranged on the inner peripheral side, whereby the thickness of the exciter 2 is reduced.

FIG. 9 shows a fifth embodiment. The elastic member 2a in FIG. 8 is a member having a small Young's modulus, such as a resin, provided on the entire upper surface of the iron core 2b, whereas in the present embodiment, the tip of the iron core 2b has a flange-shaped brim spring shape. This gives it elasticity in the axial direction.

FIG. 10 shows a sixth embodiment. In each of the above-described embodiments, the nodal diameter of the ring is 2 as the eigenmode of the rotor 1.
Although the above mode was used, another mode may be used as long as a traveling wave can be generated on the contact surface of the rotor with the exciter. Therefore, in this embodiment, a rod-shaped rotor 10 having a constricted portion 10a at the center in the longitudinal direction as shown in FIG.
The bending first-order mode of the rod as shown in FIG. On the other hand, the exciter 2 shown in FIG. 10B is always given a magnetic field that rotates while the suction force at one location is maximized. If the frequency of the attraction force is substantially equal to the natural frequency of the bending mode of the rotor, the rotor rotates while contacting the elastic member 2a, as shown in (c) of FIG.

FIG. 11 shows a seventh embodiment. The present embodiment is an example of using the in-plane (radial direction) bending mode of the rotor 30. As shown in the figure, the rotor 30 is rotated by applying a rotating exciting force to the exciter 40 that substantially matches the natural frequency of the elliptical mode. 40a is an elastic member, 40b is an iron core, 40c is a coil, and 40d is a substrate.

FIG. 12 shows an eighth embodiment. In the embodiment described so far, the exciting force as shown in FIG. 2 is generated in the exciter, but other distributions may be used. In (a) of FIG. 12, a sinusoidal magnetic flux density B is generated, and an exciting force f in a rectified form is obtained.

In FIG. 12B, a pulsed magnetic field density B is generated to obtain a pulsed excitation force f.

In FIG. 12C, the magnetic field density B of the sine wave
The excitation force f is obtained by adding the DC component to

In (d) of FIG. 12, an exciting force f is obtained by adding a direct current component to the sinusoidal magnetic field density B as in (c) of FIG. 12, but the amount of the direct current component f _DC is obtained. The effect of changing the applied pressure without changing the exciting force is obtained by changing the.

[0027]

As described above, according to the present invention, the following effects can be obtained.

Since the piezoelectric element is not used, there is a D-cost. Also, there are no parts that affect the environment.

Since the pressing force changes with the exciting force, it rotates stably even at low speeds. Also, the efficiency at low speed is good.

No bearing is required.

Since the exciter and the rotor are made of metal, the internal loss is small.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention, in which (a) is a rotor, (b) is an exciter, and (c) is a cross-sectional view of the exciter.
FIG. 6D is a perspective view showing an assembled state of the exciter and the rotor.

FIG. 2 is a diagram showing a relationship between a magnetic flux density generated in the exciter of FIG. 1 and a magnetic attraction force.

3 is a diagram showing a state in which a node diameter 2 of the rotor 1 of FIG. 1 is shown.

FIG. 4 is a schematic diagram showing a driving state of the motor shown in FIG.

FIG. 5 is a schematic diagram showing a driving state of the motor of FIG. 1, showing a driving principle.

FIG. 6 is an exploded perspective view showing a second embodiment.

FIG. 7 shows a third embodiment, (a) is a perspective view of a rotor, and (b) is a side sectional view thereof.

FIG. 8 shows a fourth embodiment, (a) is a plan view and (b) is a plan view.
Is a side sectional view thereof.

FIG. 9 is a side sectional view showing a fifth embodiment.

FIG. 10 shows a sixth embodiment, (a) is a perspective view of a rotor, (b) is a perspective view of an exciter, and (c) is a side view showing a driving state.

FIG. 11 is a plan view showing a seventh embodiment.

FIG. 12 is a waveform diagram showing the relationship between the signal applied to the drive coil and the attraction force.

FIG. 13 is a perspective view showing a conventional vibration wave motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rotor 1a ... Protrusion 1b ... Support plate 1c ... Output shaft 2 ... Exciter 2a ... Elastic member 2b ... Iron core 2c ... Coil 2d ... Substrate

Claims (1)

[Claims] 1. A vibrating element and a member in contact with the vibrating element, the vibrating element having magnetic field generating means for generating one or a plurality of magnetic fields on a contact surface with the member, and the member has The elastic traveling wave is excited in the member by driving the magnetic field generating means at a frequency substantially equal to the natural frequency, and an elliptic motion is generated in the surface particles at the contact portion of the member with the exciter. A vibration wave motor, wherein a pendulum and the member are moved relative to each other.