JPH02269482A - Ultrasonic linear motor - Google Patents

Abstract

PURPOSE:To accelerate movement and to enhance an efficiency by composing of a pair of elastic elements, a U-shaped vibrator, etc. CONSTITUTION:An ultrasonic linear motor is formed by mounting a U-shaped vibrator 2 on the upper face of groove 1a of a smooth rail 1. The vibrator 2 forms runner 6, and is composed of a pair of L-shaped elastic member 2a-2b, and a laminated ceramic actuator 2c; tapered parts 3a-3b are formed at the upper left and right parts, and laminated ceramic actuators 4-5 are mounted. As a result, the lateral amplitude of the vibration is increased to accelerate is movement.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ultrasonic linear motor that uses ultrasonic vibration of a piezoelectric element as a driving source to obtain linear displacement.

[Prior Art] In recent years, ultrasonic motors using ultrasonic vibrations of piezoelectric elements made of piezoelectric ceramics as a driving source have been developed and are used as actuators for various devices. Such an ultrasonic motor has advantages such as being small and expected to have high torque, and since it does not generate electromagnetic waves, it does not affect electromagnetic media or the like.

In an ultrasonic motor, a vibrating driving body and a driven body are brought close to each other, and vibrations of the driving body in the feeding direction are transmitted to the driven body through friction. The driving body generates oblique linear vibration or elliptical vibration, which is a combination of vibrations in directions orthogonal to each other, and can be structurally classified into vibrating piece type, vibrating piece type,
There are four types: torsional oscillator type, traveling wave type, and leg type.

As shown in FIG. 4, the vibrating piece type ultrasonic motor includes a vertically vibrating piezoelectric vibrator 11 and a vibrating piece 12 attached to the piezoelectric vibrator 11.
is installed obliquely to the contact surface of the driven body 13 and is driven by pushing the driven body 13 in a certain direction.
It has high conversion efficiency and can operate at high speed.

Furthermore, as shown in FIG. 5, the torsional vibrator type ultrasonic motor generates elliptical vibration instead of linear vibration like the vibrating piece type by attaching a torsional coupling element 15 to the piezoelectric vibrator 14. This is how it was done.

As shown in FIG. 6, a traveling wave type ultrasonic motor has a piezoelectric element 17 bonded to a vibrating body 16 formed in an annular or disk shape, and generates a bending vibration wave traveling in the circumferential direction on the vibrating body 16. This causes the contact surface with the rotor 18 to vibrate in an elliptical manner, and has the advantage of less wear due to the large contact area.

Furthermore, the leg-type ultrasonic motor was proposed by the present inventor (see Japanese Patent Application No. 318254, 1983), and is
As shown in the figure, a piezoelectric element 20 is attached obliquely to the top of a columnar vibrating body I9, and by applying longitudinal vibration of this piezoelectric element 20 to a columnar vibrating body 19, elliptical vibration is generated at its lower end surface. The running body 21 is linearly fed in the longitudinal direction of the rail 22, and has advantages such as high conversion efficiency.

[Problems to be solved by the invention] By the way, in each of the conventional ultrasonic motors mentioned above,
In each case, there were issues to be solved, such as the following.

First, in a vibrating piece type ultrasonic motor, the vibrating piece 12
Since the contact between the driven body 13 and the driven body 13 is intermittent, the rotation is unstable, and the direction of feeding of the driven body is also constant. Furthermore, a rotor vibrating piece! There are problems such as severe wear at the tip of No. 2.

Due to the structure of a torsional transducer type ultrasonic motor, it is difficult to separately control the vibration of the feed and the vibration that controls friction, and a linear motion conversion mechanism is required to use it as a linear motor. There were drawbacks such as.

Traveling wave ultrasonic motors have low energy conversion efficiency and
Similar to the above, there is a drawback that a linear motion conversion mechanism is required. Further, as a traveling wave type ultrasonic linear motor, a linear vibrating body is installed in place of the annular or disc-shaped vibrating body 16, and a traveling wave is applied to this to transmit the vibration to the driven body. However, in this case, there is a drawback that the traveling wave is excited throughout the rail, which increases energy loss and reduces efficiency.

Furthermore, the -limb type ultrasonic motor has a disadvantage in that the transverse amplitude of the elliptical vibration is small due to its structure, so that the moving speed is slow.

The present invention was made against this background, and an object of the present invention is to provide an ultrasonic linear motor that can perform linear motion at a high moving speed and has high energy efficiency.

[Means for Solving the Problems] The present invention includes a pair of elastic members and a first vibration element that is attached between one end of the elastic members and vibrates in a direction perpendicular to the mounting surface. A U-shaped vibrating body, second and third vibrating elements that are obliquely attached to both corners of the vibrating body and vibrate in a direction perpendicular to the mounting surface, and the other end of the vibrating body are in contact with each other. and a driven body having a running surface.

[Operation] According to the present invention, alternating current voltages having the same frequency and 180 degree phase difference are applied to the second and third vibrating elements, and each of the above alternating voltages is applied to the first vibrating element. When an AC voltage having the same frequency as , and a phase difference of 90 degrees is applied, each vibrating element generates a vibration that expands and contracts in a direction perpendicular to its mounting surface. In this case, the second and third vibrating elements are attached obliquely to the legs and body of the U-shaped vibrating body, so the vibrations of the second and third vibrating elements are transmitted to the legs and body of the U-shaped vibrating body. The signal is transmitted after being separated into a component in a parallel direction and a component in a perpendicular direction. Furthermore, since the first vibrating element is provided at the center of the torso, the vibration of this vibrating element has components in the parallel direction transmitted to the torso and components in the orthogonal direction transmitted to the legs. Amplify the vibrations of the components. As a result of the combination of these vibrations, diagonal linear or elliptical vibrations with large lateral amplitudes occur on the lower end surface of the legs, and these vibrations are transmitted to the driven body and cause vibrations. The body moves in a straight line in one direction. In this case, since the lateral amplitude of the vibration is large, the moving speed is fast.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing the configuration of an ultrasonic linear motor according to an embodiment of the present invention. In this figure, reference numeral 1 denotes a smooth rail, and a groove 1a having a specified width is formed in the upper surface of the rail l along its longitudinal direction.

A U-shaped vibrating body 2 is placed on the upper surface of the groove 1a of the rail 1 with both ends thereof facing downward.

The vibrating body 2 includes a pair of L-shaped elastic members 2a and 2b made of aluminum or the like and having a square cross section, and a columnar laminated ceramic actuator 2C attached between the upper ends of the elastic members 2a and 2b. The lower part thereof constitutes leg parts 3a and 3b, and the upper part constitutes a body part 3c. The laminated ceramic actuator 2C is a well-known type in which piezoelectric ceramic piles that expand and contract in the thickness direction (longitudinal effect) are laminated with electrodes sandwiched therebetween.

Further, at the upper left and upper right of the vibrating body 2, leg portions 3a,
For example, tapered portions 3d and 3d are formed at an angle of 45 degrees with respect to the body portion 3b and the body portion 3c.

The tapered portions 3d, 3d are provided with laminated ceramic actuators 4.5 that expand and contract in the lamination direction in the same manner as described above.
is installed. The running body 6 is configured in this way.

In such a configuration, a voltage of V a = E sin ωt is applied to the laminated ceramic actuator 4 at the upper left of the traveling body 6, and a voltage of V a = E sinωt is applied to the actuator 5 at the upper right.
It is assumed that a voltage of = E 5in(ωt+π) is applied, and a voltage of Vc=Ecosωt is further applied to the actuator 2c at the center of the body 3c. Note that the driving frequency of each of the above AC voltages is 99 KHz. When each of these AC voltages is applied, vibrations are generated in each of the laminated ceramic actuators 2c and 4.5, which expand and contract in a direction perpendicular to the mounting portion thereof. In this case, since the actuator 4.5 is attached obliquely to the legs 3a, 3b and the body 3C of the U-shaped vibrating body 2, the vibration of the actuator 45 is transmitted to the legs 3a, 3b and the body 3C. The signal is transmitted to both sides of the body 3C by being separated into a component in a parallel direction and a component in a perpendicular direction. In addition, since the actuator 2c is provided at the center of the body 3c,
The vibration of the actuator 2c amplifies the component in the parallel direction transmitted to the trunk 3c, and the vibration in the orthogonal direction transmitted to the legs 3a, 3b. As a result of the synthesis of these vibrations, the legs 3 a, 3 b
An oblique linear or elliptical vibration with a large lateral amplitude occurs on the lower end surface of the rail 1, and this vibration is transmitted to the rail l, causing the traveling body 6 to move linearly in the direction of the arrow X. In addition, in the above-mentioned voltage application state, the driving frequency of the traveling body 6 is 90K.
It moves in the direction of arrow X when the frequency is Hz or more, and moves in the direction of arrow Y when the frequency is less than 90 KHz. Therefore, the moving direction of the traveling body 6 can be controlled by changing the drive frequency.

In FIG. 2, the driving frequency applied to the traveling body 6 is 95.5.
It is a figure which shows the relationship between load and speed when KHz, drive voltage is 3.54 V (effective value), and load is 0 to 400 g. As shown in this figure, the maximum speed under no load is 28,5 cm/sec, and the speed is 10 cm/sec.
The driving force in cm/sec is 290g.

Next, when the AC voltage applied to the actuator 2c is stopped and the AC voltage is applied only to the actuator 4.5, the traveling body 6 moves in the direction of arrow Y when the driving frequency is 94 KHz or more, and when the driving frequency is less than 94 KHz. Move in the direction of arrow X. For example, at a drive frequency of 99 KHz, this is opposite to the moving direction in the above case, and therefore, the moving direction of the traveling body 6 can also be controlled by turning on/off the AC voltage applied to the actuator 2c.

In this way, in the embodiment described above, the leg parts 3a, 3
Since the component in the direction perpendicular to b, that is, the bending vibration, is amplified, elliptical vibration with a large transverse amplitude is generated at the lower end surfaces of the legs 3a and 3b, and therefore the moving speed of the traveling body 6 is increased. can do. Furthermore, since this elliptical vibration is caused by standing waves, it has the effect of high energy efficiency.

Note that instead of the laminated ceramic actuator 2C, a Langevin vibrator 7 or the like may be used as shown in FIG. 3.

Further, in the above embodiment, the phase relationship of each AC voltage applied to the laminated ceramic actuators 2c and 4.5 is fixed, and the moving direction of the traveling body 6 is controlled by changing the drive frequency in this state. However, alternatively, the driving frequency of each AC voltage may be fixed, and the moving direction of the traveling body 6 may be controlled by changing the phase relationship in this state.

[Effects of the Invention] As explained above, according to the present invention, the first vibration is attached between a pair of elastic members and one end of the elastic members and vibrates in a direction perpendicular to the mounting surface. a U-shaped vibrating body consisting of an element, second and third vibrating elements that are attached obliquely to both corners of the vibrating body and vibrate in a direction perpendicular to the mounting surface, and the other end of the vibrating body Since the drive body is provided with a driven body having a running surface that comes into contact with the drive body, it is possible to perform linear motion at a high moving speed, and has the effect of increasing energy efficiency.

[Brief explanation of drawings]

FIG. 1 is a side view showing the configuration of an ultrasonic linear motor according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between load and speed of the ultrasonic linear motor according to this embodiment, and FIG. The drawings showing the embodiment and FIGS. 4 to 7 are drawings showing the conventional example. l...Rail (driven body), 2...U-shaped vibrating body, 2a, 2b...L-shaped elastic member (elastic member), 2c. ...Laminated ceramic actuator (first vibration element), 4.5...
...Laminated ceramic actuator (second and third vibration elements).

Claims (1)

[Claims] (a) U-shaped vibration consisting of a pair of elastic members and a first vibration element that is attached between one end of the elastic members and vibrates in a direction perpendicular to the mounting surface. (b) second and third vibrating elements that are obliquely attached to both corners of the vibrating body and vibrate in a direction perpendicular to the mounting surface; (c) the other end of the vibrating body. 1. An ultrasonic linear motor, comprising: a driven body having a running surface that is brought into contact with the driven body.