JPH0937573A - Ultrasonic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain sufficient driving force with only one pressurization mechanism by providing the pressurization mechanism which applies pressure to a stator of a driving mechanism that contains the stator which is so located as to hold both faces of a rotor. SOLUTION: An ultrasonic actuator has a disc-like rotor 3 installed on a rotary shaft 10, two disc like stators 1 which are located on both sides of the rotor 3, and a pressurization mechanism 4 which brought the rotor 3 and the stators 1 into contact with each other. The pressurization mechanism 4 is constituted of pressurization springs, etc., which energize a second stator 1b to the rotor 3 side and transmit reaction force of torque that works on the stators 1 to a case 9 and the force transmitted to the case 9 energizes a first stator 1a to the rotor 3 side through the case 9. By this method, pressurization force works in the axis direction between the stators 1 and the rotor 3 and thereby the stators 1 and the rotor 3 are in tight contact with each other. Since the two stators are located, torque twice as large as in the case that there is only one stator can be generated and sufficient driving force can be obtained with only one pressurization mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator, and more particularly to an ultrasonic actuator which uses ultrasonic vibration energy of a vibrator using a piezoelectric element as a driving source, and is applied to driving an arm of a robot. Is something that can be done.

[0002]

2. Description of the Related Art As an actuator utilizing the piezoelectric effect of a piezoelectric element, an ultrasonic actuator for forming a traveling wave on the surface of an elastic stator by the piezoelectric element and frictionally driving a rotor in contact with the stator by the traveling wave is known. Known from the past.

FIG. 14 is a diagram for explaining the state of the traveling wave in the ultrasonic actuator, and shows the case of the traveling wave type motor. In FIG. 14, two vibration sources A and B composed of piezoelectric elements are arranged at appropriate intervals, and voltages having different phases are applied to each of Csinωt and Csinωt.
Vibration of cos ωt is generated. As a result, a traveling wave propagating rightward in the figure is formed. When the rotor 3 is placed on the stator 4 on which the traveling wave is formed and pressure is applied to the rotor, the rotor receives a force in the tangential direction due to the elliptic motion at the portion in contact with the wave front of the traveling wave, and the rotor 3 causes the arrow Move in the direction of. As a result, the rotor 3 is driven.

15 to 17 are views for constructing a conventional ultrasonic actuator using a traveling wave type motor. In FIG. 15, the conventional ultrasonic actuator is
A pair of stators 1'-1, 1'-2 and a rotor 3'are used as basic constituent elements, and one stator 1'-1 is provided with a piezoelectric element 2'to face the rotor 3'and the other stator 1'-1. 1'-2 and the pressure mechanism 4'are made to oppose. The stator 1'-2 is supported by the rotor 3'by bearings 5 '.

The pressurizing mechanism 4'is a mechanism for applying a pressurizing force to the contact surface between the stator 1'-1 and the rotor 3'to bring the stator 1'-1 and the rotor 3 'into close contact with each other. Is transmitted to the bearing 5'via the stator 1'-2. 16 is a diagram for explaining the configuration of an ultrasonic actuator in which two traveling wave type ultrasonic actuators shown in FIG. 15 are combined. In the ultrasonic actuator shown in FIG. 16, two stators 1′-1 are provided with the rotor 3 ′ interposed therebetween. Each stator 1 '
Similar to the configuration shown in FIG. 15, -1 is provided with a piezoelectric element 2 ', a pressurizing mechanism 4'and a stator 1'-2 are provided on the opposite side of the rotor 3', and is supported by a bearing 5 '. There is.

FIG. 17 is a diagram for explaining the structure of the stator 1 '. Radial grooves 12 'are formed on the surface of the stator 1'that contacts the rotor 3', and a rotary shaft 10 'is provided through an opening 13' formed in the center.

[0007]

However, the conventional ultrasonic actuator has a problem in that the generated driving force and the bearing mechanism are complicated. In the conventional ultrasonic actuator, the number of stators in contact with the rotor is one.
Since there are two or at most two, the driving force generated in the rotor is limited and it is difficult to increase the output.

It is possible to increase the driving force by providing a plurality of ultrasonic actuators each including a rotor and a stator, but a pressurizing mechanism for forming a contact pressure between the stator and the rotor. Is necessary for each stator, and therefore it is necessary to increase the pressurizing mechanism as the driving force increases, which causes a problem that the pressurizing mechanism becomes complicated.

Further, in the conventional pressurizing mechanism of the ultrasonic actuator, the reaction force of the pressurizing force for bringing the stator into contact with the rotor is applied to the bearing, so that the bearing not only supports the rotor. It is necessary to support the reaction force of this pressurizing mechanism, and sufficient strength and rigidity are required. Therefore, as the number of pressurizing mechanisms increases, the structure of the pressurizing mechanism itself becomes complicated. Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide an ultrasonic actuator capable of obtaining a sufficient driving force by one pressurizing mechanism.

[0010]

An ultrasonic actuator of the present invention is an ultrasonic actuator which uses ultrasonic vibration energy of a vibrator using a piezoelectric element as a drive source, and an elastic body having a traveling wave formed on its surface. Is a traveling wave type ultrasonic actuator that frictionally drives the rotor with a traveling wave, the rotor and the piezoelectric element being installed, and both sides of the rotor being gripped and arranged. The object of the present invention is achieved by providing at least one drive mechanism including a stator, and one pressurizing mechanism for applying a pressure to the stator of the drive mechanism.

The ultrasonic actuator of the present invention uses a drive mechanism composed of a rotor and a stator provided with a piezoelectric element as a drive unit, and the drive mechanism holds the rotor between two stators, whereby the contact area between the stator and the rotor is increased. Can be increased to increase the generated torque. Also,
A plurality of drive mechanisms is provided, one stator of one drive mechanism is brought into contact with the other stator of an adjacent drive mechanism, and the plurality of drive mechanisms are stacked in the rotation axis direction of the rotor to form a drive mechanism row. Thus, it is possible to increase the generated torque by stacking a plurality of drive mechanisms as one drive unit.

Further, in order to drive the rotor by the traveling wave formed on the stator, it is necessary to apply a pressurizing force to the contact surface between the stator and the rotor to bring them into close contact with each other. The ultrasonic actuator of the present invention applies this pressurizing force by one pressurizing mechanism. In one drive mechanism, two stators are in close contact with each other on both sides of the rotor by a pressurizing mechanism. As a result, the contact area between the rotor and the stator increases, and the generated torque increases. Also,
By stacking a plurality of drive mechanisms on a common rotating shaft, the torque generated by each drive mechanism can be added, and the torque generated by the entire drive mechanism can be increased.

The application of the pressurizing force by one pressurizing mechanism can be carried out, for example, by applying the pressurizing force from both ends of one drive mechanism or a drive mechanism train in which a plurality of drive mechanisms are laminated. As a result, it is possible to apply a pressurizing force by one pressurizing mechanism, and the number of pressurizing mechanisms can be reduced. Further, it is possible to adopt a configuration in which the rotor is the end of pressurization, or a configuration in which both ends of the drive mechanism are sandwiched and a pressurization transmission mechanism that applies pressurization in opposite directions to the drive mechanism via the ends is provided. . With this configuration, the bearing supports only the rotor, and the application of pressure from the pressure mechanism can be eliminated. Further, the rotor is slidable in the axial direction with respect to the rotary shaft, and is configured to be restrained in the circumferential direction, thereby enabling axial movement by pressurization and transmission of generated torque to the rotary shaft. .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (First Embodiment) FIG. 1 is a diagram for explaining a first embodiment of the present invention. In FIG. 1, the ultrasonic actuator is a disk-shaped rotor 3 attached to a rotary shaft 10.
And two annular stators 1 (first stator 1a, second stator 1b) arranged on both sides of the rotor 3 and a pressurizing mechanism 4 for bringing the rotor 3 and the stator 1 into contact with each other. . A piezoelectric element 2 (first piezoelectric element 2a, second piezoelectric element 2b) is installed on the stator 1, and a case 9 is installed so as to sandwich the stator and the pressurizing mechanism 4 from the outside.

The stator is formed of an elastic body and has a first
One side of the stator 1a faces one surface of the rotor 3, and the other side of the first stator 1a includes a first piezoelectric element 2a and is attached to one end of a case 9. Also, the second
One of the stators 1b faces the other surface of the rotor 3, and the other of the second stators 1b includes the second piezoelectric element 2b and is in contact with one end of the pressurizing spring 4. Further, the other end of the pressurizing spring 4 is held by the case 9. Rotor 3
The rotary shaft 10 is supported by a bearing 5.

The pressurizing mechanism 4 can be constituted by an elastic member such as a pressurizing spring. One of them presses the second stator 1b toward the rotor 3 side, and the reaction force of the torque acting on the stator 1 is applied to the case 9. introduce. This reaction force biases the first stator 1a toward the rotor 3 side via the case 9. As a result, a pressurizing force is applied between the stator 1 and the rotor 3 to press them in the axial direction, and the contact surfaces of the stator 1 and the rotor 3 are brought into close contact with each other.

Since the two pressurizing forces acting on the rotor 3 from the stator 1 are balanced with each other, the bearing 5 does not need to support the thrust force due to the pressurizing force and supports only the rotating shaft 10 of the rotor 3. By driving the piezoelectric element 2, the stator 1 generates vibration so that a traveling wave circulates in the circumferential direction. Due to the vibrational movement of the surface of the stator 1, the rotor 3 in contact with the stator 1 is driven in one direction by frictional force,
Generates torque.

According to the first embodiment, (1) since two stators are arranged on both sides of the rotor, twice the torque is generated as compared with the case where one stator 1 is provided. 2) Since the bearing does not support the pressure applied between the stator and the rotor, it is possible to reduce the frictional resistance in the bearing and to reduce the size.

In the configuration examples shown in FIGS. 2 to 5, the set of the stator and the rotor in the ultrasonic actuator shown in FIG. 1 is used as a unit drive mechanism, and a plurality of drive mechanisms are used to configure a drive mechanism array. And constitutes an ultrasonic actuator.

In FIG. 2, one drive mechanism is constituted by the rotor and the stators arranged on both sides of the rotor, and a plurality of these drive mechanisms are used to arrange them in layers. For example, a stator on one side of one drive mechanism is brought into contact with a stator on the other side of an adjacent drive mechanism, and a plurality of drive mechanisms are stacked in the rotation axis direction of the rotor to form a drive mechanism row. The stator 6a on one end side is urged toward the rotor 3 by the pressurizing mechanism 4. As for the stator 6b on the other end side of the drive mechanism row, the pressurizing force of the pressurizing mechanism 4 is transmitted through the case 9 and is biased to the rotor 3 side as in the configuration example of FIG. .

FIG. 3 is a view showing the structure of the stator. An opening 13 through which the rotary shaft 10 passes is formed at the center of a structure made of an annular elastic body, and radial grooves 12 are formed on both sides. It Further, projections 11 are radially formed on the circumferential surface of the annular structure intermittently. This protrusion 1
1 is located in a spline 7 formed in the axial direction on the inner peripheral surface side of the case 9, whereby the stator 1 can move along the spline 7 in the axial direction, but rotation in the circumferential direction does not occur. Be detained.

4 and 5 are views showing the structure of the rotor. An opening 15 for attaching to the rotary shaft 10 is opened at the center of the disk-shaped structure, and the peripheral surface of the opening 15 is shown. The projections 11 are radially formed intermittently toward the center. On the other hand, the rotating shaft 10 has an axial groove 16
To form a spline 8, and the protrusion 11 of the rotor 3 is located inside the spline 8.
The rotor 3 is movable along the spline 8 in the axial direction and is restrained by the rotation of the rotary shaft 10 in the circumferential direction.

Therefore, even if the contact surface between the rotor 3 and the stator 1 is abraded by friction and the axial distance between the rotor 3 and the stator 1 changes, the stator 1 and the rotor 3 and the stators 7, 8 are As it slides and moves along, the contact between rotor 3 and stator 1 is automatically maintained.

Further, since the pressurizing force is supported by the stator and the case at both ends of the drive mechanism, the bearing 5 supporting the rotary shaft 10 does not need to support the pressurizing force. Therefore, the bearing 5 can be downsized, and the frictional resistance can be reduced to improve the efficiency of the actuator.

Next, an example in which the ultrasonic actuator according to the first embodiment is applied to a joint drive mechanism of a robot arm will be described with reference to FIGS. 6 and 7. This application example is an example of forming a joint drive mechanism of a robot arm by combining three ultrasonic actuators 21 to 23 as shown in FIG. FIG. 7 is a cross-sectional view of the joint drive mechanism of this robot arm, showing the first ultrasonic actuator 21.
The third ultrasonic actuator 23 shows a cross section in a direction parallel to the axis, and the second ultrasonic actuator 22 shows a cross section in a direction orthogonal to the axis.

Each of the ultrasonic actuators 21 to 23 can be constituted by a drive mechanism similar to the ultrasonic actuator shown in FIG. 2, and the rotary shaft 10 has a position detector 19 such as an encoder for detecting a rotational position. Is installed, and the whole is housed in the case 9 to form one unit of the actuator. In the example shown in the figure, an example in which three actuators are combined is shown, but a joint drive mechanism can be configured by assembling as many as the number of degrees of freedom of the joints of the robot arm.

When the first embodiment is applied to a joint drive mechanism such as a robot arm, (1) a sufficient drive torque can be obtained without using a speed reducer, (2)
Since the speed reducer is not used, it is possible to eliminate an error caused by the speed reducer that occurs between the robot arm and the feedback signal of the position detector, and improve the motion accuracy and the positioning accuracy of the robot arm. (3) In the traveling wave type ultrasonic actuator, when the driving power to the piezoelectric element is stopped, the stator and the rotor are pressed by the applied pressure and the frictional force acts, so that the position of the arm is held. Therefore, there is an effect that a holding brake mechanism for that is unnecessary, and a gravity holding brake that is normally required by the robot arm can be unnecessary.

(Second Embodiment) Next, the second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. The second embodiment is different in the structure of the pressurizing mechanism 4 and is substantially the same in the other structures, and therefore only the different parts will be described below.

In FIG. 8, a pressurizing mechanism 4 for pressing the stator 1 and the rotor 3 against each other is provided on the rotor 3 side. The stator 1 is slidable in the axial direction with respect to the case 9 along the splines 7 as in the second embodiment. On the other hand, the first rotor 3a at one end of the laminated rotors 3 is fixed to the rotary shaft 10, and the other rotors 3 slide axially with respect to the rotary shaft 10 along the splines 8. It is possible. Further, one of the pressurizing mechanisms 4 is supported by a supporting portion 14 fixed to the rotary shaft 10, and the other abuts on the slidable rotor 3.

As a result, the pressurizing force of the pressurizing mechanism 4 makes contact between the rotor 3 and the stator 1 which are slidable between the support portion 14 fixed to the rotary shaft 10 and the first rotor 3a. . Even when the contact surface between the rotor 3 and the stator 1 is abraded by friction and the axial distance between the rotor 3 and the stator 1 is changed, the stator 1 and the rotor 3 are also changed.
Since it slides and moves along the stators 7 and 8, the contact between the rotor 3 and the stator 1 is automatically maintained.

Further, in comparison with the second embodiment, the stator has a structure in which all the surfaces thereof come into contact with the rotor, and thus it is possible to contribute to the generation of the driving torque.

In the second embodiment, in addition to the effect of the first embodiment, (1) the structure of the stator can be made common. (2) The pressurizing force of the pressurizing mechanism 4 is the rotating shaft. The rotor mounted on the rotor 10 and the inside of the supporting portion can be closed, and it is not necessary to transmit the pressurizing force by the case 9, and the structure can be simplified.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. In the third embodiment, as shown in FIG. 9, the ultrasonic actuator includes two disk-shaped rotors 3 (first rotor 3a, second rotor 3b) mounted on a rotary shaft 10 and a space between the two rotors 3. The two annular stators 1 (first stator 1a, second stator 1b) sandwiched between the rotor 1 and the rotor 3 provided between the first stator 1a and the second stator 1b are brought into contact with each other. The pressurizing mechanism 4 is provided. The first piezoelectric element 2a is installed on the stator 1a, and the second piezoelectric element 2b is installed on the stator 1a.

The stator is formed of an elastic body and has a first
The stator 1a faces one surface of the first rotor 3a, the other side of the first stator 1a abuts one end of the pressurizing mechanism 4 to receive a pressurizing force, and the other side of the second stator 1b receives the second rotor 3b. The other side of the second stator 1b is in contact with the other side of the pressurizing mechanism 4 to receive the pressurizing force. The rotary shaft 10 of the rotor 3 is supported by the bearing 5 with respect to the case 9.

The pressurizing mechanism 4 can be constituted by an elastic member such as a pressurizing spring, one of which is the first stator 1a and the first stator 1a.
The rotor 3a is urged, and the second stator 1 is urged on the other side.
B is urged to the second rotor 3b side. Thereby, the first
The contact between the stator 1a and the first rotor 3a and the contact between the second stator 1b and the second rotor 3b are performed.

By driving the piezoelectric element 2, the stator 1 generates vibration so that a traveling wave circulates in the circumferential direction. Due to the vibrational movement of the surface of the stator 1, the rotor 3 in contact with the stator 1 is driven in one direction by frictional force,
Generates torque. Further, the torque acting on the rotor 3 on the axially moving side via the pressurizing mechanism 4 is transmitted to the rotary shaft 10 via the spline 8.

According to the third embodiment, (1) the contact area between the stator and the rotor is doubled, so that twice the torque is generated as compared with the conventional ultrasonic actuator. ) When the distance between the stator and the rotor changes due to wear between the stator and the rotor, the stator is moved in the axial direction with respect to the rotor side by the pressurizing force of the pressurizing mechanism 4, so that the distance is automatically adjusted. (3) Since the bearing does not support the pressure applied between the stator and rotor,
The frictional resistance in the bearing can be reduced, and the size can be reduced.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. 4th
10, the ultrasonic actuator comprises a disk-shaped first rotor 3a attached to the rotary shaft 10, a disk-shaped second rotor 3b movable axially by a spline 8, and One annular stator 1 sandwiched between the two rotors 3 and the second rotor 3b
A pressurizing mechanism 4 for contacting the rotor 3 and the stator 1 provided between the rotor 3 and the supporting portion 17 fixed to the rotating shaft 10 is provided.

The stator 1 is formed in a shape in which the surface facing the first rotor 3a and the surface facing the second rotor 3b are not symmetrical, and the piezoelectric element 2 is installed. Further, the surfaces of the first rotor 3a and the second rotor 3b that face the stator 1 are formed in a non-symmetrical manner according to the shape of the stator 1. Further, the stator is formed of an elastic body, and the outer peripheral side thereof is elastically attached to the case 9 via a stator support portion 18 formed in an annular shape. When the rotor and the stator move in the axial direction, this stator support 1
The elastic support of 8 makes it possible to compensate for this movement.

The pressurizing mechanism 4 can be constituted by an elastic member such as a pressurizing spring, one of which biases the second stator 1b toward the rotor 3 side, and the other of which is supported by the supporting portion 17. As a result, the contact between the first rotor 3a and the stator 1 and the contact between the second rotor 3b and the stator 1 are performed.

When the traveling wave is driven by the piezoelectric transverse effect of the piezoelectric element 2, the stator 1 vibrates so that the traveling wave circulates in the circumferential direction. Due to the oscillating motion of the surface of the stator 1, the rotor 3 in contact with the stator 1 is driven in one direction by a frictional force to generate torque. Further, the torque acting on the rotor 3 on the axially moving side via the pressurizing mechanism 4 is transmitted to the rotary shaft 10 via the spline 8.

According to the fourth embodiment, (1) the contact area between the stator and the rotor is doubled, so that twice the torque is generated as compared with the conventional ultrasonic actuator. ) When the gap between the stator and rotor changes due to wear, the pressure of the pressurizing mechanism and the elastic support of the stator cause axial movement of the stator and rotor, and the distance is automatically adjusted. Is done,
(3) Since the bearing does not support the pressurizing force applied between the stator and the rotor, it is possible to reduce the frictional resistance in the bearing and to reduce the size.

(Fifth Embodiment) Next, the fifth embodiment of the present invention will be described.
The embodiment will be described with reference to FIGS. 11 and 12. The fifth embodiment has substantially the same structure as the second embodiment shown in FIG. 8 and is different in the structures of the piezoelectric element and the stator. Therefore, only different points will be described below.

The piezoelectric element 2 according to the second embodiment utilizes the piezoelectric lateral effect to generate undulating vibrations in the stator. Therefore, in the second embodiment, piezoelectric elements are attached to the back sides of the vibrating surfaces on both sides of the stator, respectively, and a gap is provided between the two piezoelectric elements to constrain the mutual vibrations. On the other hand, the fifth embodiment utilizes the vibration in the thickness direction generated in the stator 1 by the piezoelectric vertical effect of the piezoelectric element 2. Therefore, as shown in FIG. 11, in the second embodiment, the piezoelectric element 2 is provided in the middle of the adjacent rotor 3 side of the stator 1, and the vibration in the vertical direction of one piezoelectric element 2 is applied to both sides of the stator 1. The configuration is such that it is transmitted to the rotor 3.

FIG. 12 is a diagram for explaining the relationship between the stator and the piezoelectric element. As shown in (a) of FIG. 12, the piezoelectric element 2 shown by diagonal lines is divided into two parts with respect to the stator 1, and the voltages A and B have different phases as shown in (d) of FIG. 12, respectively. Driven by, the thickness changes according to the phase. By driving with this different phase voltage,
Vibration as shown in FIGS. 12B and 12C is generated in one stator.

The ultrasonic actuator has the piezoelectric element 2
Rotational torque is generated in the rotor 3 by the vertical vibration of.
According to the fourth embodiment, in addition to the effects of the second embodiment, (1) it is possible to reduce the number of piezoelectric elements, and (2) therefore, it is possible to reduce the size and the number of parts. The effect is that it can be done. (Other Embodiments) In the above-described embodiments, an example in which the stator and the rotor are formed in an annular shape is shown, but a configuration in which these are arcuate is also possible.
FIG. 13A shows an example of a configuration in which the annular stator 1 is an arc-shaped rotor 3, and FIG. 13B is an example of a configuration in which an annular rotor is combined with an arc-shaped stator.

[0047]

As described above, according to the present invention,
It is possible to provide an ultrasonic actuator capable of obtaining a sufficient driving force by one pressurizing mechanism.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a laminated structure according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a stator in the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a rotor according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of a rotor and a rotary shaft according to the first embodiment of the present invention.

FIG. 6 is a schematic external view of an example in which the first embodiment of the present invention is applied to a joint drive mechanism of a robot arm.

FIG. 7 is a sectional view of an example in which the first embodiment of the present invention is applied to a joint drive mechanism of a robot arm.

FIG. 8 is a diagram illustrating a second embodiment of the present invention.

FIG. 9 is a diagram illustrating a third embodiment of the present invention.

FIG. 10 is a diagram illustrating a fourth embodiment of the present invention.

FIG. 11 is a diagram illustrating a fifth embodiment of the present invention.

FIG. 12 is a diagram illustrating a relationship between a stator and a piezoelectric element according to a fifth embodiment of the present invention.

FIG. 13 is a diagram illustrating another mode of the present invention.

FIG. 14 is a diagram for explaining a state of a traveling wave in the ultrasonic actuator.

FIG. 15 is a diagram for configuring a conventional ultrasonic actuator using a traveling wave motor.

FIG. 16 is a diagram for configuring a conventional ultrasonic actuator using a traveling wave motor.

FIG. 17 is a diagram for configuring a conventional ultrasonic actuator using a traveling wave motor.

[Explanation of symbols]

 1,1a, 1b, 6a, 6b Stator 2,2a, 2b Piezoelectric element 3,3a, 3b Rotor 4 Pressurizing mechanism 5 Bearing 7,8 Spline 9 Case 10 Rotating shaft 11,14 Projection part 12,16 Groove 13,15 Opening part 14,17 Support part 18 Stator support part 19 Position detector 20 Detector 21,22,23 Actuator

Claims (5)

[Claims] 1. A traveling wave type ultrasonic actuator, comprising: an elastic stator having a traveling wave formed on a surface thereof; and a rotor in contact with the stator, wherein the rotor is frictionally driven by the traveling wave. Is provided and at least one drive mechanism including a stator arranged to grip both sides of the rotor, and one pressurization mechanism for applying a preload to the stator of the drive mechanism. Ultrasonic actuator. 2. A plurality of drive mechanisms are provided, one stator of one drive mechanism is brought into contact with the other stator of an adjacent drive mechanism, and the plurality of drive mechanisms are stacked in the rotation axis direction of the rotor to drive. The ultrasonic actuator according to claim 1, wherein a mechanism row is configured, and the one pressurizing mechanism applies pressure from both ends of the drive mechanism row. 3. The ultrasonic actuator according to claim 1, wherein the pressurizing mechanism uses a rotor as an end of pressurizing. 4. The pressurizing mechanism is provided with a pressurizing force transmitting mechanism that grips both ends of the drive mechanism and applies pressurizing forces in opposite directions to the drive mechanism via the end portions. Item 3. The ultrasonic actuator according to item 1, 2 or 3. 5. The ultrasonic actuator according to claim 1, wherein the rotor is slidable in the axial direction with respect to the rotating shaft and is constrained in the circumferential direction.