JPH09219979A - Vibration actuator - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: In a deformed mode degenerate vibration actuator utilizing longitudinal vibration and torsional vibration, the moving element tilts as it is driven, resulting in uneven rotation, uneven torque, and left / right difference. The efficiency will decrease. SOLUTION: A fixed shaft 10, a vibrator 2 which is supported by the fixed shaft 10 and generates a plurality of vibrations, and a fixed shaft 10
A movable body 12 which is rotatably supported by the movable body 12 and is rotationally driven by being brought into pressure contact with the end face of the vibrator 2; One bearing 13 and a power take-off member 16 installed on the mover 12 for transmitting the rotation of the mover 12 to the outside
In the ultrasonic actuator 1, the power takeoff member 16 is installed at substantially the same position as the installation position of the bearing 13 in the direction of the fixed shaft 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator, and more particularly to a vibration actuator which suppresses a decrease in drive efficiency due to power take-out as much as possible.

[0002]

2. Description of the Related Art FIG. 14 is a perspective view showing a structure of a conventional example of a longitudinal-torsion vibration type vibration actuator.

Conventionally, in this type of vibration actuator, in a stator (stator) 101, a piezoelectric element 10 for torsional vibration is provided between two cylindrical vibrators 102 and 103.
4 are arranged. Further, a piezoelectric element 105 for longitudinal vibration is arranged above the vibrator 103. The piezoelectric element 104 for torsional vibration is polarized in the circumferential direction. On the other hand, the piezoelectric element 105 for longitudinal vibration is polarized in the thickness direction. Further, the rotor (moving element) 106 is arranged above the piezoelectric element 105 for longitudinal vibration.

A vibrator 102 constituting a stator 101,
103 and the piezoelectric elements 104 and 105
It is screwed and fixed to the screw part of the. The rotor 106 is rotatably provided on the shaft 107 via a ball bearing 108 provided at the center. A nut 110 is screwed into the tip of the shaft 107 via a spring 109.
As a result, the rotor 106 is brought into pressure contact with the stator 101 with a predetermined pressing force F.

The piezoelectric element 104 for torsional vibration and the piezoelectric element 105 for longitudinal vibration are driven by the phase shifter 112 controlling the phase shift of the voltage of the same frequency oscillated from the oscillator 111.

The piezoelectric element 104 for torsional vibration gives a mechanical displacement for rotating the rotor 106. On the other hand, the piezoelectric element 105 for longitudinal vibration includes the stator 101 and the rotor 1.
The frictional force acting between the piezoelectric element 104 and the piezoelectric element 104 is periodically changed in synchronization with the cycle of the torsional vibration by the piezoelectric element 104, thereby playing a role of a clutch for converting the vibration into a unidirectional motion.

FIG. 15 is an exploded perspective view showing a stator 101 of this conventional vibration actuator. The piezoelectric element 104 for torsional vibration needs to be polarized in the circumferential direction. Therefore, as shown in FIG.
One end was divided into about eight fan-shaped pieces, and each piece was polarized and then reassembled into a ring shape. Reference numeral 104a in FIG. 15 is an electrode.

[0008]

However, in the above-mentioned conventional vibration actuator, the piezoelectric element 1 for torsional vibration is used.
When combining 04 with a ring shape, it was difficult to obtain the ring shape accuracy.

On the other hand, the area of each of the piezoelectric element 105 for longitudinal vibration and the piezoelectric element 104 for torsional vibration is substantially equal to the sectional area of the stator 106 or smaller than the sectional area of the stator 106. It was Moreover, in order to penetrate the shaft 107, the piezoelectric element 10 for longitudinal vibration is used.
It was also necessary to make a hole in the center of each of the piezoelectric elements 104 for torsional vibration and. Therefore, the area of each of the piezoelectric element 105 for longitudinal vibration and the piezoelectric element 104 for torsional vibration is further reduced, and it is difficult to increase torque and rotation of the vibration actuator.

In order to solve such a problem, the applicant of the present invention has already disclosed in Japanese Patent Application No. 6-275022 or the like a variant which can be driven with a high torque and a high rotation and is easy in structure and manufacturing. We proposed a vibration actuator using a mode-degenerate oscillator.

The vibration actuator using the modified mode degenerate oscillator has a higher torque and a smaller size than a conventional vibration actuator using a plurality of same-mode vibrations represented by an annular type. Furthermore, the possibility of weight reduction and the like is expected, and development has been actively promoted in recent years.

As a vibration actuator using a modified mode degenerate type vibrator, there is a vibration actuator using a longitudinal-torsion vibration type vibrator. There are several types of vibration actuators using this longitudinal-torsional vibration. Among them, there is a type in which the longitudinal vibration and the torsional vibration are set in the vicinity of the same frequency, and an elliptic motion, which is a combination of displacements of the longitudinal vibration and the torsional vibration, is used as a driving force.

FIG. 4 shows a modified mode degenerate vibration actuator 1 in which the resonance frequencies of longitudinal vibration and torsional vibration are matched by devising the shape of the vibrator 2 alone.
FIG.

FIG. 5 is an explanatory view showing the arrangement of the piezoelectric bodies 3 and 4 in the vibrator 2, and FIG. 5 (a) is a side view showing the left half from the center line of the vibrator 2 in section. 5 (b)
Is the AA cross section, the BB cross section, and the CC in FIG.
It is explanatory drawing which shows a cross section with the application condition of drive voltage Vt, Vl.

As shown in FIGS. 5 (a) and 5 (b),
The vibrator 2 joins the piezoelectric bodies 3 and 4 which are electromechanical conversion elements excited by a drive signal, and the piezoelectric bodies 3 and 4 are joined to each other to excite the piezoelectric bodies 3 and 4 to cause primary longitudinal vibration and secondary longitudinal vibration. The elastic body 5 is configured to generate a driving force on the driving surface D when the torsional vibration is generated.

As can be seen from FIGS. 4 and 5, the elastic body 5 has four large-diameter portions 6A to 6D and four large-diameter portions 6A which are formed apart from each other in the direction parallel to the central axis direction. ~ 6
Three small-diameter portions 6a formed in a step shape between each D
It is obtained by recombining the two semi-hollow cylindrical bodies 5a and 5b obtained by vertically dividing the hollow cylindrical body provided with ˜6c into two in the plane including the central axis.

Piezoelectric bodies 3 and 4 which are plate-shaped electromechanical conversion elements are held in a state of being sandwiched between the divided surfaces of the two semi-hollow cylindrical bodies 5a and 5b. The piezoelectric body has a primary longitudinal vibration (L1
Two layers of the piezoelectric body 4 having a large piezoelectric constant d ₃₁ are arranged at one place near the node of (mode), and the secondary torsional vibration (T2
Two layers of the piezoelectric body 3 having a large piezoelectric constant d ₁₅ are arranged at two places near the (mode) node.

In the elastic body 5, through holes 7a to 7d are formed in parallel with the stacking direction of the piezoelectric bodies 3 and 4 at substantially the centers of the four large diameter portions 6A to 6D in the elastic body length direction. Bolts 8a to 8d are inserted into these through holes 7a to 7d, and nuts 9a to 9d are respectively screwed into the bolts 8a to 8d to fasten and fix the semi-hollow columnar bodies 5a and 5b and the piezoelectric bodies 3 and 4. To do.

Further, the elastic body 5 is provided at a predetermined position of the round rod-shaped fixed shaft 10 in the vicinity of the node of the primary longitudinal vibration (L1 mode), which is a substantially central portion of the small diameter portion 6b in the longitudinal direction of the elastic body. It is installed in a state in which the pin 11, which is a support member for fixing to, is penetrated.

The mover 12 is a thick ring-shaped mover base material 1
2a, and a sliding member 12b that is attached to one end surface of the mover base material 12a and contacts the elastic body driving surface D. Positioning with respect to the fixed shaft 10 is performed by a bearing 13 which is a rotation supporting member fitted to the inner peripheral portion of the end face of the moving element base material 12a on the side opposite to the oscillator. In addition, a coil spring 14 (which may be a disc spring, a leaf spring, or the like) serving as a pressurizing unit is fixed to a predetermined position of the fixed shaft 10, and the coil spring 14 directs the vibrator 2 toward the elastic body driving surface D. Is pressurized.

In the vibration actuator shown in FIG. 4, the mover 12 is supported by a single bearing 13, but there are also some in which two bearings are arranged on both end surfaces of the mover base material 12a. However, if the moving element 12 is supported by the two bearings in this way,
Therefore, it is desirable that the moving element 12 be supported by one bearing, because it may excessively restrain the moving element 12 and the driving efficiency of the vibration actuator may be lowered.

The fixed shaft 10 is arranged so as to pass through the hollow portion of the vibrator, fixes the vibrator 2 and positions and supports the mover 12 in the radial direction thereof.
Further, a screw portion is formed on the upper end of the fixed shaft 10, and a nut 15 which is an adjusting means for adjusting the pressing force of the coil spring 14 is screwed onto the screw portion. The pressing force of the coil spring 14 is adjusted by adjusting the screwing position of the nut 15 with respect to the fixed shaft 10.

As shown in FIG. 5B, the drive circuit oscillates the drive signal and the oscillated drive signal into a signal having a phase difference of (1/4) λ (λ: wavelength). Phase-shifting part 22 to separate and piezoelectric body for torsional vibration (PZT for T) 3,
3 includes a T amplification unit 23 that amplifies a drive signal that is input to 3 and an L amplification unit 24 that amplifies the drive signal that is input to the longitudinal vibration piezoelectric body (PZT for L) 4.

As shown in FIG. 5 (b), the elastic body 5 vertically divides the hollow columnar body into two, and holds the piezoelectric bodies 3 and 4 in a state where the divided planes are sandwiched. Piezoelectric bodies 3 and 4 are 3
Each of the piezoelectric bodies 3 and 4 is composed of two layers.

As described above, the piezoelectric body 4 of one group among the piezoelectric bodies 3 and 4 of the three groups has a piezoelectric body with a large piezoelectric constant d ₃₁ remaining at one location near the node of the primary longitudinal vibration. In the second group of piezoelectric bodies 3 and 3, piezoelectric bodies having a large piezoelectric constant d ₁₅ are arranged at two locations near the node of the secondary torsional vibration.

The piezoelectric body 3 having a large piezoelectric constant d ₁₅ causes shear displacement in the longitudinal direction of the elastic body 5. FIG. 5 (b)
2 in each of the AA cross section and the CC cross section in FIG.
The pair of piezoelectric bodies 3 are arranged so that the shear deformation is alternately in the front direction and the opposite direction with respect to the circumferential direction of the elastic body 5.

The piezoelectric bodies 3 are arranged so that the twisting directions of the AA cross section and the CC cross section are opposite to each other. When the piezoelectric bodies are arranged in this way and each is sheared and deformed, a secondary torsional vibration is generated in the vibrator 2.

The piezoelectric body 4 having a large piezoelectric constant d ₃₁ expands and contracts in the longitudinal direction of the elastic body 5. FIG. 5 (b)
The two sets of piezoelectric bodies 4 for longitudinal vibration in the BB cross section are arranged so that displacement occurs in the same direction when a certain potential is applied.

As described above, the piezoelectric body 3 for torsional vibration having a large piezoelectric constant d ₁₅ and the piezoelectric body 4 for longitudinal vibration having a large piezoelectric constant d ₃₁ are arranged in advance for torsional vibration. Piezoelectric body 3
When a sine wave voltage is input to the oscillator 2, a torsional motion is generated in the oscillator 2 accordingly. On the other hand, when a sine wave voltage is input to the piezoelectric body 4 for longitudinal vibration, the vibrator 2 expands and contracts accordingly.

With the above configuration, the oscillator 21 oscillates a drive signal, and the drive signal is divided by the phase shifter 22 into two signals having a (1/4) λ phase difference, each of which is a T amplifier. It is amplified by 23 and the L amplifier 24. T
The drive signal amplified by the amplifier 23 is input to the piezoelectric body 3 for torsional vibration. On the other hand, the drive signal amplified by the L amplifier 24 is input to the piezoelectric body 4 for longitudinal vibration.

FIG. 6 shows the longitudinal vibration (L1
3) and a torsional vibration (T2 mode). As shown in FIG. 6, the vibrator 2 to which the drive signal is input is excited by the piezoelectric bodies 3 and 4, and has a primary longitudinal vibration having a vibration antinode and a node 2
The following torsional vibrations occur. Here, if the phase difference between the drive voltages applied to the piezoelectric body 3 for torsional vibration and the piezoelectric body 4 for longitudinal vibration is set to be shifted by (1/4) λ, the drive surface D of the vibrator 2 has an elliptic motion. Occurs.

When such an elliptic motion is generated on the driving surface D, torsional vibration (T2 mode) generates nodes at two locations of the small diameter portions 6a and 6c having a small torsional rigidity, and the end surface The drive surface D, which is, becomes the antinode of vibration. On the other hand, the longitudinal vibration (L1 mode) generates a node near the small diameter portion 6b, and the drive surface D becomes an antinode. The mover 12 pressed against the drive surface D is driven by frictionally receiving a drive force from the vibrator 2.

FIG. 7 is an explanatory diagram showing over time that an elliptic motion occurs on the driving surface D of the vibrator 2. FIG.
The moving element is not shown in FIG. As shown in FIG. 7, when the phase difference between the period of the torsional vibration (T2 mode) and the period of the longitudinal vibration (L1 mode) is shifted by (1/4) λ, the driving surface D of the vibrator 2 is set. Elliptic motion occurs at the fixed point of.

At time t = (6/4) π, the displacement of the torsional vibration T is maximum on the left side, while the displacement of the longitudinal vibration L is zero. In this state, the mover is brought into pressure contact with the drive surface D of the vibrator 2 by a pressure mechanism (not shown).

From this state, t = (7/4) π˜0
Up to (2/4) π, the torsional vibration T is displaced from the maximum on the left side to the maximum on the right side, while the longitudinal vibration L is displaced from zero to the maximum on the upper side and returns to zero again. Therefore, the fixed point of the driving surface D of the vibrator 2 rotates rightward while pressing the moving element, and the moving element is driven.

Next, from t = (2/4) π to (6/4) π, the torsional vibration T is displaced from the maximum on the right side to the maximum on the left side, while the longitudinal vibration L is zero. Then, it moves to the lower maximum and returns to zero again. Therefore, the fixed point of the drive surface D of the vibrator 2 rotates to the left while moving away from the moving element, so that the moving element is not driven. At this time, the moving element has different natural frequencies even if it is pressed by the pressing member, so that the vibrator 2
Does not follow the shrinkage of

Here, when the frequency of the torsional vibration is made to substantially match the resonance frequency of the torsional vibration and the frequency of the longitudinal vibration is made to substantially match the resonance frequency of the longitudinal vibration, both the torsional vibration and the longitudinal vibration are resonated. Then the elliptical movement expands.

By the way, in the vibration actuator shown in FIG. 4, unless the mover 12 itself driven by the vibrator 2 is a final drive symmetrical object, the mover 12 takes out power for transmitting the driving force to the outside. It is necessary to further provide a section. As such a power take-out part, the mover 12
Since is driven to rotate, it is generally provided on the outer peripheral surface of the mover 12.

8 and 9 are partial sectional views showing a vibration actuator in which a gear 16 as a power take-out portion is formed on the outer peripheral surface of the mover 12. FIG. 8 shows a gear 16
Is installed on the vibrator 2 side, and FIG. 9 is a case where the gear 16 is installed on the anti-vibrator 2 side.

In the vibration actuator shown in FIGS. 8 and 9, the gear 16 is formed in an annular shape on a part of the outer peripheral surface of the mover 12, and a gear (not shown) of a power transmission target member is meshed with the gear 16. By doing so, the driving force generated in the mover 12 is extracted. However, if an attempt is made to extract the driving force in this manner, the mover 12 will be tilted or whirling due to the driving.

FIG. 10 shows the state of the moving element 12 in which the vibration actuator shown in FIG. 8 is tilted or whirling, and FIG. 11 is the vibration actuator shown in FIG. 9 in which tilting or whirling is generated. It is explanatory drawing which shows the situation of each mover 12.

As shown in FIGS. 10 and 11, when the power take-out portion 16 is meshed with the drive force transmitting gears 18a and 18b formed in a part of the power transmitting target members 17a and 17b, respectively, FIG. In the vibration actuator shown in FIG. 9, the mover 12 tilts with respect to the fixed shaft 10 and swirls around the installation position of the ball bearing 13 in the longitudinal direction of the fixed shaft 10. Such inclination and whirling of the mover 12 are particularly remarkable when the length of the mover 12 in the rotation axis direction is large. The mover 12 tilts or swings around in this manner because there are distances h ₁ and h ₂ between the bearing installation position and the gear 16 installation position in the longitudinal direction of the fixed shaft 10. is there.

When the vibration due to the inclination or whirling of the moving element 12 approaches the natural frequency of the fixed shaft 10 or the surrounding system, chatter vibration or noise is generated in the moving element 12. There is a fear.

Further, as an example of the variant mode degenerate oscillator, the above-described longitudinal-torsion oscillator type vibration actuator moves the rotational displacement due to the torsional vibration generated in the oscillator 2 to the moving element. The vertical amplitude due to longitudinal vibration is used for intermittently transmitting to 12 (clutch-like). Therefore, when a slight inclination or whirling of the moving element 12 occurs, the vibrator driving surface D that is displaced in the order of micron to submicron,
That is, the contact state (parallelism of surfaces, surface pressure state, etc.) between the vibrator 2 and the mover 12 is significantly affected. Therefore, in the vibration actuator in which the mover 12 is tilted,
At the time of driving, uneven rotation, uneven torque, left-right difference, lowering of driving efficiency, etc. occur, and the performance of the vibration actuator deteriorates.

Further, FIGS. 12 and 13 both show the case where the power take-out portion for taking out the power is changed to the belt 19 which is a transmission mechanism. 12 and 13, belt 19 may or may not be a toothed belt.

Ordinary belt 19 whose transmission mechanism is not toothed
In the case of, the moving element 12 and the power transmission target member 17 are
A mechanical relationship is maintained that is linked by the frictional force generated between the surface of each of the mover 12 and the power transmission target member 17 and the belt 19. Therefore, it is necessary to give sufficient tension to the belt 19 to generate a frictional force. If the transmission mechanism is the toothed belt 19, it is necessary to set an appropriate tension on the belt 19 in order to accurately transmit the rotational force.

However, in the vibration actuators shown in FIGS. 12 and 13, similarly to the vibration actuators shown in FIGS. 8 to 11 described above, the moving element 12 is tilted to cause tilting or whirling of the moving element 12. Occurs, causing uneven rotation, uneven torque, left-right difference, and lower efficiency.

[0048]

In order to solve such a problem, according to the present invention, a power take-out portion is provided in the axial direction of the fixed shaft in the vicinity of the installation position of the rotary support member of the mover. It suppresses the occurrence of tilt and whirling.

According to a first aspect of the present invention, a fixed shaft, a columnar vibrator supported by the fixed shaft and generating a plurality of vibrations, and a vibrator rotatably supported by the fixed shaft are provided. A columnar relative movement member that is pressed against the end face of the rotor and is driven to rotate by the vibration, and a rotary support that is installed on the relative movement member and rotatably supports the relative movement member with respect to the fixed shaft. In a vibration actuator comprising a member and a power take-out member that is installed on the relative motion member and transmits the rotation of the relative motion member to the outside, the power take-out member has the rotation support in the fixed axial direction. It is characterized in that it is installed at substantially the same position as the installation position of the member.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the rotation supporting member is
It is characterized by being a bearing. The invention of claim 3 is the vibration actuator according to claim 1 or 2, wherein the vibration actuator is
It is a characteristic mode degenerate vibration actuator that utilizes a plurality of different vibration modes.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the following description of each embodiment will be given by taking an ultrasonic actuator that uses an ultrasonic vibration region as an example of the vibration actuator.

FIG. 1 is a partial sectional view of an ultrasonic actuator according to the first embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing a situation where the driving force is taken out by this ultrasonic actuator. Except for the range shown in FIGS. 1 and 2, the vibration actuator is the same as that shown in FIGS. 4 to 7, and therefore the description of the range not shown in FIGS. 1 and 2 is omitted.

In the first embodiment shown in FIGS. 1 and 2, an annular groove 12c is formed in the center of the upper end surface of the mover 12,
The bearing 13 is fitted into the groove 12c and mounted. By mounting the bearing 13 at a predetermined position on the fixed shaft 10, the movable element 12 is rotatably supported by the fixed shaft 10.

In the present embodiment, the gear 16 as a power take-out member is formed in an annular shape on the outer peripheral surface of the moving element 12 which is at the same height as the installation position of the bearing 13 in the longitudinal direction of the fixed shaft 10.

In the first embodiment shown in FIGS. 1 and 2, the gear 16 is provided at the same height as the bearing 13 and the gear 1 is formed in the power transmission target member 17a in an annular shape.
The power is taken out from 8a. Therefore, the load applied to the gear 16, that is, the external force applied to the moving element 12 directly acts on the bearing 13 which plays the role of the center of rotation of the moment.

In other words, the mechanical influence of the power transmission target member 17a, which is an external load, on the mover 12 is generated in the bearing 13 in the longitudinal direction of the fixed shaft 10. That is, the external force from the power transmission target member 17a to the mover 12 acts in the vicinity of the rotation center point of the moment generated when the mover 12 is tilted or whirles.

As described above, according to the present embodiment, the acting portion of the external force from the power transmission target member 17a exists near the position where the moment for tilting the mover 12 is generated. The value can be made extremely small. Therefore, the inclination and whirling of the mover 12 can be suppressed to an extremely low level. Although the gear 16 is formed at the same height as the bearing 13 in the present embodiment, the present invention is not limited to such a mode. The gear 16 may be installed in the vicinity of the installation position of the gear 16 to the extent that it does not matter even if a moment that tilts the mover 12 is generated.

(Second Embodiment) FIG. 3 is a partial sectional view of an ultrasonic actuator according to a second embodiment of the present invention. The ultrasonic actuator of the present embodiment is one in which the power take-out member for taking out power is changed to the belt 19 which is a power transmission mechanism.

That is, as shown in FIG.
Instead of providing the gear 16 for taking out power on the outer peripheral surface of the ball bearing 13 in the longitudinal direction of the fixed shaft.
The annular belt 19 is hung at the same height as that of the belt 19 and the gear 18a for extracting the driving force of the power transmission target member 17a is arranged at the same height.
Drive force is taken out via.

According to the ultrasonic actuator of this embodiment, even if the belt 19 is tensioned, the bearing 1
3 and the belt 19 are at the same height, the moving element 1
2 does not tilt. Therefore, the inclination and whirling of the mover 12 can be suppressed to an extremely low level, and the ultrasonic actuator can be operated extremely stably.

As described above, according to the ultrasonic actuators of the first and second embodiments, since the power is taken out from the vicinity of the rotary support member of the moving element, which is the relative moving member, the moving element of the moving element is removed. Tilt and whirling can be suppressed to an extremely low level. Therefore, the surface pressure of the sliding surface between the vibrator and the mover can be stably maintained. Therefore, it is possible to prevent the occurrence of rotation unevenness, torque unevenness, left-right difference, and efficiency reduction when driving the ultrasonic actuator.

(Modifications) In each of the embodiments, an ultrasonic actuator using vibration in the ultrasonic region is taken as an example of the vibration actuator, but the vibration actuator according to the present invention is not limited to such a mode. The same can be applied to vibration actuators that utilize vibrations in other vibration regions.

Further, in each of the embodiments, the piezoelectric body is used as the electromechanical conversion element, but it is equally applicable as long as it can convert electric energy into mechanical displacement. For example, an electrostrictive element or a magnetostrictive element may be used instead of the piezoelectric body.

Further, in each of the embodiments, the ultrasonic actuator in which the first-order longitudinal vibration and the second-order torsional vibration are generated in the vibrator is taken as an example, but the present invention is limited to such a mode. However, it is not
The same can be applied to any vibration actuator that generates the following torsional vibration (m, n: natural number) and uses a combined vibration of these vibrations as a driving force.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an ultrasonic actuator according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a situation where a driving force is extracted by the ultrasonic actuator according to the first embodiment of the present invention.

FIG. 3 is a partial sectional view of an ultrasonic actuator according to a second embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of a variant mode degenerate vibration actuator in which the resonance frequencies of the longitudinal vibration and the torsional vibration of the vibrator alone are matched.

5 (a) and 5 (b) are explanatory views showing the arrangement of piezoelectric bodies in a vibrator, FIG. 5 (a) is a side view showing a left half from a center line of the vibrator in a cross section, and FIG. A-A in a)
The drive voltage Vt, Vl is applied to the cross section, the BB cross section, and the CC cross section.
FIG. 4 is an explanatory diagram showing the state of application of.

FIG. 6 is an explanatory diagram showing an example of vibration waveforms of longitudinal vibration (L1 mode) and torsional vibration (T2 mode) generated in the vibrator.

FIG. 7 is an explanatory diagram showing over time that an elliptical motion occurs on the driving surface D of the vibrator.

FIG. 8 is a cross-sectional view showing an example in which a gear as an output take-out portion is annularly formed on the outer peripheral surface of a moving element.

FIG. 9 is a cross-sectional view showing an example in which a gear as an output take-out portion is formed in an annular shape on the outer peripheral surface of a moving element.

10 is an explanatory diagram showing a state of a moving element in which tilting or whirling has occurred in the vibration actuator shown in FIG.

FIG. 11 is an explanatory diagram showing a state of a moving element in which tilting or whirling has occurred in the vibration actuator shown in FIG. 9.

FIG. 12 is an explanatory diagram showing a case where a power take-out section for taking out power is changed to a belt.

FIG. 13 is an explanatory diagram showing a case where a power take-out portion for taking out power is changed to a belt.

FIG. 14 is a perspective view showing the structure of a conventional example of a vertical-torsion vibration type vibration actuator.

FIG. 15 is a perspective view showing a developed stator of the conventional vibration actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic actuator (vibration actuator) 2 Vibrator 3 Piezoelectric body for torsional vibration 4 Piezoelectric body for longitudinal vibration 5 Elastic bodies 5a, 5b Semi-cylindrical elastic body 6A to 6D Large diameter part 6a to 6c Small diameter part 7a to 7d Through hole 8a-8d Bolt 9a-9d Nut 10 Fixed shaft 11 Pin 12 Moving element 12a Moving element base material 12b Sliding material 13 Bearing 14 Coil spring 15 Nut 16 Power extraction part 17 Power transmission object member 18 Gear 19 Belt

Claims (3)

[Claims] 1. A fixed shaft, a columnar vibrator supported by the fixed shaft and generating a plurality of vibrations, rotatably supported by the fixed shaft, and pressure-contacted to an end face of the vibrator. A columnar relative movement member that performs relative movement with the vibrator by the vibration, and a rotation support member that is installed on the relative movement member and rotatably supports the relative movement member with respect to the fixed shaft. A vibration actuator that is installed on the relative motion member and that transmits a rotation of the relative motion member to the outside, wherein the power extraction member is the installation position of the rotation support member with respect to the fixed axis direction. A vibration actuator, which is installed at substantially the same position. 2. The vibration actuator according to claim 1, wherein the rotation support member is a bearing. 3. The vibration actuator according to claim 1 or 2, wherein the vibration actuator is a modified mode degenerate vibration actuator that utilizes a plurality of different vibration modes.