JPH01136576A - Supersonic motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field The present invention relates to improvements in ultrasonic motors.

A conventional ultrasonic motor usually includes two members that are movable relative to each other and pressed against each other, and is configured to generate surface acoustic waves on the pressure surfaces of the two members to move the two members relative to each other. For example, in a rotary motor, the above two members are
It consists of a vibrating member whose position is fixed and a rotating body that is rotatable around one axis while being in pressure contact with the vibrating member, and the locus of a point on the pressure contact surface of the vibrating member draws an ellipse. The vibrating member is caused to vibrate in a vibration mode.

Problems to be Solved by the Invention Incidentally, generally speaking, ultrasonic vibration generating elements for exciting a vibrating member vibrate in one direction. When vibrating, the shape and size of the vibrating member are determined so that a mechanical resonance system is formed in which the ultrasonic vibration generating element is mounted so that the parts vibrate in one direction, but the surfaces in contact with each other generate elliptical vibration. It is normal to Therefore, the major axis/minor axis ratio of the elliptical vibration generated on the pressure contact surface of the vibrating member excited by the single natural vibration mode of the ultrasonic vibration generating element is determined by the shape of the ultrasonic vibration generating element. ,
There is a drawback that controlling the ultrasonic motor may be difficult.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The gist is that: (b) a first vibrating member including a first press contact surface and configured to vibrate in a unidirectional vibration mode; (C) a first ultrasonic vibration generating element that is attached to the device and excites the first vibration member; a second vibrating member having two press-contact surfaces and configured such that the second press-contact surface vibrates in a vibration mode in a direction different from the one direction; and a second ultrasonic vibration generating element that excites the member.

Operation and Effect of the Invention With this structure, the first vibrating member is excited by the first ultrasonic vibration generating element and is vibrated in a vibration mode in which the pressure contact surface vibrates in one direction, while the second vibrating member is Second
By being excited by the ultrasonic vibration generating element and vibrating the pressure contact surface in a vibration mode in which the pressure contact surface vibrates in a direction different from one direction, the pressure contact surface of the first vibration member and the pressure contact surface of the second vibration member are made to vibrate. be moved relative to each other.

Generally, the frequency of the natural vibration of a vibrating member in a single direction is not affected by the magnitude of the vibrating member in a direction orthogonal to the natural vibration of the vibrating member. Further, a first ultrasonic vibration generating element that excites the first vibrating member is attached in a plane perpendicular to the vibration direction of the first pressure contact surface of the first vibrating member, and excites the second vibrating member. The second ultrasonic vibration generating element is attached to the second pressing surface of the second vibrating member within a plane perpendicular to the vibration direction. Therefore, when attaching the first vibrating member and the second vibrating member to the first ultrasonic vibration generating element and the second ultrasonic vibration generating element that excite them, the area of the first vibrating member, the second vibrating member, and the first ultrasonic vibration generating element and the second ultrasonic vibration generating element that excites them is limited to an area that affects the natural vibration mode of the vibrating member itself. Since the vibration amplitude can be increased without causing any damage, the amplitude of the vibration can be changed freely, and the desired motor output can be obtained without impairing the control characteristics.

Here, if the ultrasonic motor is of a linear morph type, the first vibrating member and the second vibrating beam are moved relative to each other along a straight line. However, if the ultrasonic motor is a rotary motor type, the first vibrating member and the second vibrating member are relatively rotated around one axis. In this case, preferably, the first vibrating member is configured such that its first pressing surface vibrates in a circumferential vibration mode, and the second vibrating member is configured such that its second pressing surface vibrates in the axial vibration mode. It is configured to vibrate at .

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, a holder 10 has a cylindrical shape with a bottom, and is fixed to a fixed member (not shown) such as a machine frame. A rotating shaft 12 is slidably fitted to the bottom of the holder 10, and a nut 1 is screwed onto one end of the rotating shaft 12.
4 and the bottom surface inside the holder 10, a preloaded coil spring 15 and a thrust bearing 16 are inserted, so that the rotation shaft 12 can be rotated and the nut 1 can be rotated.
It is constantly biased toward the 4th side.

The fixed vibration member 18 is fixed concentrically to the holder 10, and has a through hole 20 formed therein, into which the rotating shaft 12 is loosely fitted, as shown in detail in FIGS. 2 and 3. , a boss portion 22 fixed to the holder 10 and having a square axial cross section, and a rectangular flat plate portion 24 that protrudes the same length in all directions from four sides of the outer periphery of the boss portion 22 and is located within a plane containing the axis. and an annular pressure contact portion 26 that connects one corner of the outer peripheral side of the flat plate portion 24 to each other.

Because it is configured in such a shape, a pair of piezoelectric elements 28 are attached to both sides of the longitudinal center portion of each flat plate portion 24.
When a high-frequency drive signal is supplied to the fixed-side vibrating member 1 in a vibration mode in which the first press-contact surface 30 provided on one surface in the axial direction of the annular press-contact portion 26 vibrates exclusively in the circumferential direction,
8 can be made to vibrate. In this example,
The fixed side vibrating member 18 functions as a first vibrating member, and the piezoelectric element 28 functions as a first ultrasonic vibration generating element.

A movable vibration member 32, which functions as a second vibration member in this embodiment, is fixed to the other end of the rotating shaft 12. As shown in detail in FIGS. 4 and 5, the movable vibrating member 32 includes a boss portion 34 having a square shaft cross section into which the other end of the rotating shaft 12 is fitted, and an outer periphery of the boss portion 34. A rectangular flat plate part 36 that protrudes the same length from four sides in all directions and is located in a plane perpendicular to the axis, and the outer circumferential end of this flat plate part 36 are interconnected, and the annular pressure welding and an annular pressure contact portion 38 having a second pressure contact surface 42 that is brought into pressure contact with the first pressure contact surface 30 of the portion 26 . Because of this configuration, when a high-frequency drive signal is supplied to the piezoelectric elements 40 affixed to each pair of piezoelectric elements 40 on both sides of the longitudinal center portion of the flat plate portion 36, the piezoelectric elements 40 are applied to one surface of the annular pressure contact portion 38 in the axial direction. The movable vibration member 32 is configured to vibrate in a vibration mode in which the second pressure contact surface 42 provided opposite the first pressure contact surface 30 vibrates exclusively in the axial direction. In this embodiment, the piezoelectric element 40 functions as a second ultrasonic vibration generating element.

In the ultrasonic motor configured as described above, a drive signal from a control device (not shown) is transmitted to the piezoelectric elements 28 and 4.
0, the fixed side vibration member 18 is supplied to the piezoelectric element 28
The movable vibrating member 32 is excited by the piezoelectric element 40 and the first pressure contact surface 30 is vibrated in a circumferential vibration mode, while the movable vibration member 32 is excited by the piezoelectric element 40 and the second pressure contact surface 4
2 is vibrated in a vibration mode in which it vibrates in the axial direction perpendicular to the circumferential direction, thereby causing the fixed side vibration member 18 and the movable side vibration member 32 to rotate relative to each other.

That is, between each drive signal supplied from the control device to the piezoelectric elements 28 and 4°, one point facing each other on the first pressure contact surface 3° and the second pressure contact surface 42 is connected to the movable vibration member 32.
The vibration causes the first and second pressure contact surfaces 30.42 to come closest to each other.
When the pressing force at is maximum, the fixed side vibrating member 18
A certain phase relationship is provided such that the circumferential vibration of is approximately at a maximum. By reversing the phase relationship of the drive signals, the rotation direction of the ultrasonic motor is reversed, and by increasing and decreasing the amplitudes of the drive signals, the ultrasonic motor is controlled to a desired rotational speed. Ru. In the ultrasonic motor of this embodiment, since the fixed vibration member 18 is provided in a fixed position, the torque output from the rotating shaft 12 is utilized.

In this embodiment, the fixed side vibrating member 18 is configured so that its first pressure contact surface 30 vibrates exclusively in a vibration mode in which it vibrates in the circumferential direction, and the movable side vibrating member 3
2 is configured such that its second pressure contact surface 42 is vibrated exclusively in a vibration mode in which it vibrates in the axial direction.

Generally, when a vibrating member has natural vibration in a single direction, the piezoelectric element that excites it is installed in a plane orthogonal to the single direction, and the natural frequency is orthogonal to the vibration in the single direction. It does not depend on the size of the vibrating member in the direction of vibration. Therefore, the fixed side vibrating member 18, the movable side vibrating member 32, and the piezoelectric element 28 that excites them.
The mounting area with the piezoelectric element 4o can be increased without affecting each vibration mode, so the vibration amplitude can be freely changed and the desired motor output can be obtained without impairing the control characteristics. For example, in the flat plate parts 24 and 36, if the plate thicknesses t and t' are constant, the natural frequency in the circumferential direction is hardly affected even if the width dimension and h' are changed. ri and h
By increasing the contact area with the piezoelectric elements 28 and 40, a large output torque can be obtained.

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, in the ultrasonic motor of the above embodiment, the fixed vibration member 18 is provided in a fixed position, the movable vibration member 32 is rotatably provided, and torque is output from the rotating shaft 12. However, on the contrary, there is no problem even if the movable vibration member 32 is fixed in position and the fixed vibration member 18 is rotatably provided.

Further, although the fixed side vibrating member 18 and the movable side vibrating member 32 of the above-mentioned embodiment are each provided with four flat plate portions 24 and 36, they may have two, three, or five or more flat plate portions. Alternatively, the flat plate portions 24 and 36 may be separate members from the boss portions 22 and 34 or the annular pressure contact portions 26 and 38.

Furthermore, in the above embodiment, a pair (two) of piezoelectric elements 38 and 40 were attached to both surfaces of the flat plate portions 24 and 36 of each of the fixed vibration member 18 and the movable vibration member 32, respectively. , the piezoelectric elements 38 and 40 may be attached one by one, or every other piezoelectric element 38 and 40 may be attached on the flat plate portions 24 and 36.

Further, in the above-mentioned ultrasonic motor, the rotational driving force is output from the rotary shaft 12 fixed to the movable vibration member 32 which is rotatably provided, but the movable vibration member is fixed. It may also be configured as a so-called linear motor type that is provided so as to be movable relative to the side vibration member along a straight line. In this case, the first pressure contact surface provided on the fixed vibration member is formed parallel to the above-mentioned - straight line, and the second pressure contact surface of the movable vibration member is brought into pressure contact with a part of the first pressure contact surface.

Further, in the above embodiment, the fixed vibration member 18 is configured such that the first pressure contact surface 30 is caused to vibrate naturally in the circumferential direction, and the second pressure contact surface 42 is caused to vibrate in a direction perpendicular to the circumferential direction, i.e. Although the movable side vibration member 32 was configured to cause natural vibration in the axial direction, the first pressure contact surface 30
Even if the vibration directions of the second pressure contact surface 42 and the second pressure contact surface 42 are not perpendicular to each other, a certain effect can be obtained as long as they are in different directions.

The above-mentioned embodiment is merely one embodiment of the present invention, and the present invention can be modified in various ways without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of an embodiment of the present invention. 2 and 3 are a plan view and a partially cutaway front view of the stationary vibrating member shown in FIG. 1. FIG. 4 and 5 are a plan view and a partially cutaway front view of the movable vibration member shown in FIG. 1. FIG. 18; Fixed side vibration member (first vibration member) 28: Piezoelectric element (first ultrasonic vibration generating element) 30: First pressure contact surface 32: Movable side vibration member (second vibration member) 40: Piezoelectric element (second Ultrasonic vibration generating element) 42: Second pressure contact surface Applicant: Brother Industries, Ltd.] Figure 2

Claims (2)

[Claims] (1) a first vibration member including a first pressure contact surface and configured to vibrate in a unidirectional vibration mode;
a first ultrasonic vibration generating element attached to the first vibrating member to excite the first vibrating member; and a first ultrasonic vibration generating element that is movable relative to the first vibrating member in the one direction and is in pressure contact with the first pressure contact surface. a second vibrating member that is attached to the second vibrating member and configured to vibrate in a vibration mode in a direction different from the one direction; An ultrasonic motor comprising: a second ultrasonic vibration generating element that excites two vibrating members. (2) The first vibrating member and the second vibrating member are provided so as to be relatively rotatable around a common axis, and the first vibrating member has a first pressure contact surface in a circumferential vibration mode. Claim 1, wherein the second vibration member is configured such that the second pressure contact surface vibrates in a vibration mode in the axial direction.
The ultrasonic motor described in section.