JP2622286B2 - Ultrasonic linear motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic linear motor for obtaining a linear displacement by using ultrasonic vibration of a piezoelectric element as a driving source.

[Related Art] In recent years, ultrasonic motors using ultrasonic vibration of a piezoelectric element made of piezoelectric ceramics as a driving source have been developed and used as actuators for various devices. Such an ultrasonic motor is expected to be small and have high torque,
Since there is no generation of electromagnetic waves, there is an advantage that there is no influence on an electromagnetic medium or the like.

The ultrasonic motor brings a vibrating driving body and a driven body close to each other, and transmits vibration in a feed direction of the driving body to the driven body via friction. The driving body performs oblique linear vibration or elliptical vibration that combines vibrations in directions perpendicular to each other, and when structurally classified, it can be divided into vibrating reed type, torsional vibrator type, traveling wave type, and single leg type. There are four types.

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

In addition, the torsional vibrator type ultrasonic motor generates an elliptical vibration instead of a linear vibration like a vibrating piece type by providing a torsional coupling element 15 to the piezoelectric vibrator 14 as shown in FIG. It is like that.

As shown in FIG. 6, the traveling wave type ultrasonic motor is configured such that a piezoelectric element 17 is joined to a vibrating body 16 formed in an annular or disk shape, and a bending vibration wave traveling in a circumferential direction is applied to the vibrating body 16. By giving it, the contact surface with the rotor 18 is caused to elliptically vibrate, and has an advantage that the contact area is large and the wear is small.

The single-foot type ultrasonic motor has been proposed by the present inventor (see Japanese Patent Application No. 63-318254). As shown in FIG. Piezoelectric element 20
The longitudinal vibration of the piezoelectric element 20 is attached to the columnar vibrating body 19
In this case, the traveling body 21 is linearly fed in the longitudinal direction of the rail 22 by generating an elliptical vibration at the lower end surface, and has advantages such as high conversion efficiency.

[Problems to be Solved by the Invention] By the way, each of the conventional ultrasonic motors described above has the following problems to be solved.

First, in a vibrating piece type ultrasonic motor, the vibrating piece 12
The rotation of the driven body is unstable because the contact between the driven body and the driven body 13 is intermittent, and the direction of feed of the driven body is also constant.
Further, there is a problem that the tip of the rotor vibrating piece 12 is severely worn.

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

The traveling wave type ultrasonic motor has a drawback that the energy conversion efficiency is low and a linear motion conversion mechanism is required as described above. In addition, as a traveling wave type ultrasonic linear motor, a linear vibrating body may be installed instead of the ring or disk shaped vibrating body 16, and a traveling wave may be given to this to transmit vibration to a driven body. However, in this case, since the traveling wave is excited in the entire rail, the energy loss is further increased, and the efficiency is reduced.

The single-foot type ultrasonic motor has a drawback that the moving speed is slow because the lateral amplitude of the elliptical vibration is small due to its structure.

The present invention has been made under such a background,
It is an object of the present invention to provide an ultrasonic linear motor that can perform a 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 vibrating element mounted between one ends of the elastic members and vibrating 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,
A driven body having a running surface with which the other end of the vibrating body is in contact.

According to the present invention, AC voltages having the same frequency and a phase difference of 180 degrees are applied to the second and third vibrating elements, respectively, and the AC voltage is applied to the first vibrating element. When an AC voltage having the same frequency as the above and having a phase difference of 90 degrees is applied, each of the vibrating elements generates a vibration that expands and contracts in a direction perpendicular to the mounting surface. In this case, since the second and third vibrating elements are obliquely attached to the legs and the trunk of the U-shaped vibrating body, the vibrations of the second and third vibrating elements are caused by the legs and the trunk. Are divided into components in the parallel direction and components in the orthogonal direction, respectively, and transmitted. In addition, since the first vibration element is provided at the center of the body, the vibration of the vibration element reflects the component in the parallel direction transmitted to the body and the component in the orthogonal direction transmitted to the legs. Amplifies component vibration. Then, as a result of the synthesis of these vibrations, oblique linear or elliptical vibrations having a large lateral amplitude are generated on the lower end surface of the leg, and the vibrations are transmitted to the driven body, and The body moves linearly in one direction. In this case, the moving speed is high because the lateral amplitude of the vibration is large.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing a configuration of an ultrasonic linear motor according to one embodiment of the present invention. In this figure, reference numeral 1 denotes a smooth rail, and a groove 1a having a predetermined width is formed on the upper surface of the rail 1 along the longitudinal direction.
A U-shaped vibrator 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 is formed of aluminum or the like, and has a pair of L-shaped elastic members 2a and 2b having a square cross section, and the elastic members 2a and 2b.
And a columnar laminated ceramic actuator 2c attached between the upper ends of the upper and lower portions 2b, whereby the lower portion is the leg portions 3a and 3b and the upper portion is the trunk portion 3c. The multilayer ceramic actuator 2c is a well-known one in which piezoelectric ceramic plates that expand and contract in the thickness direction (vertical effect) are stacked with electrodes interposed therebetween.

The upper left and upper right portions of the vibrating body 2 have legs 3a, 3
Tapered portions 3d, 3d are formed at an angle of, for example, 45 degrees with respect to b and the trunk 3c. And this taper part 3d, 3d
Are mounted with laminated ceramic actuators 4 and 5 which expand and contract in the laminating direction in the same manner as above. The traveling body 6 is configured in this manner.

In such a configuration, a voltage of Va = Esinωt is applied to the multilayer ceramic actuator 4 at the upper left of the traveling body 6 and a voltage of Vb = Esin (ωt + π) is applied to the actuator 5 at the upper right. Actuator in the center of part 3c
A voltage of Vc = Ecosωt is applied to 2c. The driving frequency of each of the AC voltages is 99 KHz. When each of these AC voltages is applied, the above-mentioned multilayer ceramic actuator 2c,
In the cases 4 and 5, vibrations that expand and contract in a direction perpendicular to the mounting surface are generated. In this case, actuators 4,5
Is mounted obliquely with respect to the legs 3a, 3b and the trunk 3c of the U-shaped vibrating body 2, so that the vibration of the actuators 4, 5 is applied to both the legs 3a, 3b and the trunk 3c. Each component is transmitted after being decomposed into a component in a parallel direction and a component in a direction orthogonal to each other. Also, since the actuator 2c is provided at the center of the body 3c, the vibration of the actuator 2c
The component in the parallel direction transmitted to the torso 3c and the leg 3
Amplifies the vibration of the component in the orthogonal direction transmitted to a and 3b. And as a result of the synthesis of these vibrations,
On the lower end surfaces of a and 3b, oblique linear or elliptical vibrations having a large lateral amplitude are generated, and the vibrations are transmitted to the rail 1 so that the traveling body 6 linearly moves in the arrow X direction. In the above-described voltage applied state, the traveling body 6 has a drive frequency of 90.
It moves in the arrow X direction above KHz, and moves in the arrow Y direction below 90 KHz. Therefore, the moving direction of the traveling body 6 can be controlled by changing the driving frequency.

FIG. 2 shows that the driving frequency applied to the traveling body 6 is 95.5 KH.
z, drive voltage is 3.54V (effective value), load is 0-400g
It is a figure which shows the relationship between load and speed at the time of setting. As shown in this figure, the maximum speed at no load is 28.5 cm / sec, and the propulsion at a speed of 10 cm / sec is 290 g.

Next, when the AC voltage applied to the actuator 2c is stopped, and the AC voltage is applied only to the actuators 4 and 5, the traveling body 6 moves in the arrow Y direction at a drive frequency of 94 KHz or more, and moves at a drive frequency of less than 94 KHz. Move in arrow X direction.
For example, at a driving frequency of 99 KHz, the moving direction is opposite to the moving direction in the case described above. Therefore, the moving direction of the traveling body 6 can be controlled also by turning on / off the AC voltage applied to the actuator 2c.

As described above, in the above-described embodiment, by providing the laminated ceramic actuator 2c vibrating in the longitudinal direction at the center of the body 3c of the vibrating body 2, the components of the legs 3a and 3b in the direction perpendicular to each other, Since the vibration is amplified, elliptical vibration having a large lateral amplitude is generated on the lower end surfaces of the legs 3a and 3b, and therefore, the moving speed of the traveling body 6 can be increased. Further, since the elliptical vibration is caused by the standing wave, there is an effect that the energy efficiency is high.

In addition, instead of the multilayer ceramic actuator 2c, a Langevin vibrator 7 or the like may be used as shown in FIG.

Further, in the above embodiment, the phase relationship between the AC voltages applied to the multilayer ceramic actuators 2c, 4, 5 is fixed, and the moving direction of the traveling body 6 is controlled by changing the driving frequency in this state. However, in addition, the driving direction 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 described above, according to the present invention, a pair of elastic members are attached between one end of the elastic members,
A U-shaped vibrating body composed of a first vibrating element vibrating in a direction perpendicular to the mounting surface, and a second and a second vibrating body mounted diagonally on both corners of the vibrating body and vibrating in a direction perpendicular to the mounting surface. 3 and a driven body having a running surface with which the other end of the vibrating body abuts, so that linear motion with a high moving speed can be performed, and energy efficiency can be reduced. There is an effect that can be increased.

[Brief description of the drawings]

FIG. 1 is a side view showing the configuration of an ultrasonic linear motor according to one 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. FIGS. 4 to 7 show an example of the prior art. 1 ... rail (driven body) 2 ... U-shaped vibrating body, 2a, 2
b ... 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)

(57) [Claims] 1. A U-shaped vibrating body comprising: a pair of elastic members; and a first vibrating element mounted between one end of the elastic members and vibrating 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; and (c) the other end of the vibrating body is An ultrasonic linear motor, comprising: a driven body having a running surface in contact therewith.