JPH0731168A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To provide an ultrasonic motor in which the rotation can be detected with high resolution without projecting the ultrasonic motor to the outside of the case. CONSTITUTION:A drive module 1 is brought into external contact with a rotary drum 2 to cause rotary driving. A disc 3 is disposed integrally with the rotary drum 2 and a frictional disc 4 is pressed against the outer radial part thereof. The disc 3 has a diameter smaller than the height of the drive module 1 and a plurality of substantially conical protrusions 4a and recesses 3a are provided at the frictional transmission parts of both discs in order to prevent slip through mating. A rotation detector is linked with the frictional disc 4 and integrally fitted in a case 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor, and more particularly to the rotation detection of an ultrasonic motor in which a drive module is circumscribed on a rotary drum to obtain rotary drive.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic motor for circumscribing a drive module on a rotary drum and detecting its rotation to obtain rotational drive is shown in FIGS. FIG. 3 is a front view of an essential part showing an example of a rotation detector of a conventional ultrasonic motor, and FIG. 4 is a side view of FIG. 3, in which a drive module 16 integrally constructed by using a piezoelectric element or the like is provided outside the rotary drum 11. The shaft 11a, which is elastically circumscribed by the mounting bracket 17 on the diametrical part, is rotatably supported by the shaft 11a integrated with the rotary drum 11, and the output end is drive-coupled to the rotation detector 13 via the coupling 12 and mounted. The cylinder 14 is attached to the motor case 15, and these are integrally constructed to detect the rotation of the ultrasonic motor.

A method of driving the ultrasonic motor having the above-described structure and a method of detecting its rotation will be described. When a required pulsed power source is supplied to the driving module 16, the lower surface of the pressing portion of the driving module 16 makes an elliptic motion. A wave (not shown) is synthesized, and the rotary drum 11 pressed against this surface rotates by transmitting the wave motion by friction drive. A shaft 11a is integrated with the rotary drum 11, and a detector 13 is rotated via a coupling 12 in association with the shaft 11a, where rotation detection is performed by a general rotation detection method such as an optical or magnetic method. Be done.

[0004]

However, in the above-mentioned structure, the case 15 of the ultrasonic motor is projected to the outside by the amount of the coupling 12 and the rotation detector 13 (δ in the figure). Originally, the ultrasonic motor has the characteristics of low speed, high torque, small size and light weight as compared with the electric motor, and it can be placed directly on the robot etc. even if it uses gears etc., and it can be made compact. It has become extremely important for applications such as mobile robots that move. However, since the protrusions (δ in the figure) are generally 2 to 4 times as long as the thickness of the ultrasonic motor body, the ultrasonic motor is compact enough to be applied to a space-saving place such as the aforementioned self-propelled robot. However, because of the above-mentioned protrusion δ,
The labor saving space is impaired, which is a serious problem. The present invention was devised in view of the above-mentioned points, and an object of the present invention is to obtain an ultrasonic motor that eliminates such drawbacks.

[0005]

[Means for Solving the Problems] That is, in order to achieve the object, an ultrasonic motor in which a drive module is circumscribed on a rotary drum to obtain a rotary drive module is integrally formed on a side portion of the rotary drum. A plate 3 is arranged, a friction disk 4 having a diameter E equal to or smaller than the height L of the drive module is pressed against the outer diameter portion of the disk 3, and the rotation detector 5 is linked thereto. These are attached to the inside of the case of the ultrasonic motor to be integrally configured, and rotation detection is performed without protruding outside the case of the ultrasonic motor. Also,
A plurality of substantially cone-shaped protrusions and depressions are formed in the friction transmission portions of the pressing contact portions of the friction discs 4 and 3, respectively, and the engagement prevents slippage and corrects the positional deviation.

[0006]

The operation will be described in combination with the embodiment described below.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. 1 is a front view of an essential part showing an embodiment of the present invention, and FIG. 2 is a side view of FIG. 1. In FIGS. 1 and 2, a drive module 1 is circumscribed on a rotary drum 2 and elastically attached by a mounting bracket. It is fixed to the case 6 to obtain rotational drive. A disc 3 is arranged on the side of the rotary drum, and the disc 3 is drivingly linked with the rotary drum 2, and the friction circle having a diameter E equal to or smaller than the height L of the drive module 1 is provided on the outer diameter portion of the disc 3. The plate 4 is pressed into contact with the friction disc 4 and a plurality of substantially conical and convex friction deviation preventing gold 4a are formed on the outer diameter portion of the friction disc 4. A plurality of discs 3 to be pressed against each other are formed at the same pitch as the conical recesses 3a having substantially the same shape corresponding to the protrusions, and the engagement prevents the discs 3 and the friction discs 4 from slipping. The rotation detector 5 is driven and linked to the friction disk 4, and these are mounted in the case 6 of the ultrasonic motor to be integrally constructed. The rotation is detected without protruding to the outside.

The driving of the ultrasonic motor constructed as above and the method of detecting the rotation thereof will be described. When the required pulsed power source is supplied to the driving module 1, the driving module 1
A wave (not shown) having an elliptical motion is synthesized on the lower surface of the pressing contact of the rotating drum 2, and the rotary drum 2 pressed against this surface rotates by transmitting the motion of the wave by friction drive, and is linked to the circle. The plate 3 also rotates at the same speed. Further, the friction disc 4 pressed against this also rotates due to the friction transmission of the pressing portion. The accuracy and resolution of rotation detection are extremely important, and since they are transmitted by friction in this drive etc., some slip is caused in the transmission system between the disc 3 and the friction disc 4 due to impact or accidents during various acceleration / deceleration. It may occur. Therefore, even if this deviation occurs, the substantially conical projections and recesses 3a and 4a formed on the friction surfaces of both discs 3 and 4 are corrected to the center of the pitch by the conical triangular inclination effect.
Misalignment is prevented. Therefore, since the minimum correction interval of this deviation is related to the pitch, the pitch increment may be determined according to the purpose of use.

When the friction disk 4 rotates, the rotation detector 5 is drivingly linked to the rotation, so that rotation detection is performed here. Further, in the actual design, the rotating drum 2 is composed of a plurality of drive modules 1 compared to the size of the drive module 1.
The diameter of the disc 3 can be made as large as this, and the small diameter E of the friction disc 4 is smaller than that of the drive module 1. Since the height L is equal to or smaller than the height L, the rotational speed of the disk 3 is increased with respect to the friction disk 4 by this diameter ratio.
The rotation angle to the rotation detector 5 is expanded by this amount, so that it can be detected with high resolution. Outer diameter of rotating drum 2 in prototype
Is 120 mm, the diameter of the friction disc 4 is about 40 mm,
A resolution improvement of 3 times was obtained from the diameter ratio of 120/40. Therefore, rotation detection is performed with high resolution without protruding outside the case 6 and without slipping.

[0010]

As described above, according to the present invention, the rotation can be detected without protruding to the outside of the case 6 of the ultrasonic motor, and the rotation detector 13 and the coupling of the conventional example can be detected.
Since there are no protrusions δ at all compared to external protrusions δ such as 12, it is possible to achieve a very useful space saving. Especially, it can be easily applied to a self-propelled robot. Further, in the present invention, the dimension in the width direction is increased by the thickness of the discs 3 and the friction discs 4, but since this is about several mm, it is a tenth of the projection δ in comparison with the conventional projection δ, so there is no problem. Further, since the outer diameter of the friction disk 4 can be made smaller than the outer diameter of the disk 3, the speed is increased by this diameter ratio, the rotation angle to the rotation detector 5 is expanded, the resolution is increased, and the accuracy is improved. Good rotation detection is obtained.
This is especially important for ultrasonic motors, and the driving speed is lower (about 1/30) than that of electric motors, so even in this state, rotation can be detected accurately by increasing the speed, which is highly effective for precise positioning. Is obtained.

[Brief description of drawings]

FIG. 1 is a front view of a main part of rotation detection of an ultrasonic motor according to the present invention.

FIG. 2 is a sectional view taken along the line of FIG.

FIG. 3 is a front view of a main part of rotation detection of a conventional ultrasonic motor.

FIG. 4 is a side view of FIG.

[Explanation of symbols]

 1 Drive module 2 Rotating drum 3 Disc 3a Conical recess 4 Friction disc 4a Conical protrusion 5 Rotation detector 6 Case 7 Mounting bracket 11 Rotating drum 11a Shaft 12 Coupling 13 Rotation detector 14 Mounting cylinder 15 Case 16 Drive module 17 Mounting bracket

Claims (1)

[Claims] 1. An ultrasonic motor for rotatively driving a rotary drum by circumscribing a drive module, wherein a disc is arranged on a side of the rotary drum, and the disc is drivingly linked to the rotary drum. A friction disk having a diameter E equal to or smaller than the height L of the drive module is pressed against the diameter portion, and a plurality of substantially anti-friction friction preventing gold 4a having a substantially conical shape is attached to the outer diameter portion of the friction disk. Individually formed, this protrusion 4a on the disk of the pressing partner
Corresponding to the above, a plurality of conical recesses 3a of approximately the same shape are formed at the same pitch, and the engagement prevents slippage between the disc and the friction plate and the displacement is corrected, and rotation detection is performed on this friction disc. An ultrasonic motor, characterized in that the devices are driven and linked, and these are attached inside a case of the ultrasonic motor to be integrally configured, and rotation detection is performed with high resolution without protruding outside the case of the ultrasonic motor.