JP3359167B2 - Ultrasonic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator for driving a driven body by generating ultrasonic vibration by an electromechanical transducer such as a piezoelectric element or an electrostrictive element.

[0002]

2. Description of the Related Art Referring to FIGS.
The conventional ultrasonic actuator 100 disclosed in Japanese Patent No. 039011 will be described. In the conventional ultrasonic actuator 100, as shown in FIG. 9, two electromechanical transducers 112 are fixed on one surface of a rectangular parallelepiped resonator 111 to form an ultrasonic transducer 113.

A sliding protrusion 115 is fixed to a surface of the ultrasonic transducer 113 opposite to a surface on which the electromechanical transducer 112 is mounted, and a driven body 117 is pressed against the sliding protrusion 115. The driven body 117 is driven. The ultrasonic actuator 100 is supported at its center by a projection 11 arranged at a node of vibration.
6 is performed.

In the ultrasonic actuator 100, as a driving principle, a primary longitudinal vibration (A direction vibration) of the resonator 111 shown in FIG. 10 and a secondary bending vibration (B direction vibration) also shown in FIG. The size of the resonator 111 is determined so as to match the resonance frequency of (2), and the driving power with a phase shift of 90 degrees is supplied to the two electromechanical transducers 112 at that frequency to generate an elliptical vibration in the resonator 111. Then, the driven body 117 is driven by pressing the driven body 117 against the driven body 117.

[0005]

The above-mentioned ultrasonic actuator
Considering the balance of forces when driving the motor 100, FIG.
The relationship is as follows. Central node position of ultrasonic transducer 113
Pressing force W on the projection 116 ₁Is applied, and this reaction force
The sliding protrusion 115 is disposed symmetrically with respect to the slide 16.
Reaction force W evenly in minutes_Two(= 1 / 2W₁) Occurs. Ma
Also, the ultrasonic vibrator 113 exerts a thrust on the driven body 117.
This reaction force is applied to the ultrasonic vibrator 113 to provide F1.
F in part 116_ROccurs as At this time, the ultrasonic vibrator 1
13 has M ₁A directional moment occurs. actually
Since the ultrasonic transducer 113 does not rotate,
A reaction force is generated against the sliding protrusion 115 and the protrusion 11.
Point P on 6₁, P_TwoConsidering the above, the moment is (F_R
・ L₁= 2 · L_Two・ R₁) And point P_TwoIn
(Drag R_Two= F_R・ L₁/ 2 · L_Two)
And P₁R for the point₁Of the same absolute value in the opposite direction to_Two
Is working.

FIG. 13 summarizes this relationship, and it can be seen that the normal force applied to the sliding protrusion 115 during driving is unbalanced. Due to this unbalanced vertical force, the driving force transmitted from each sliding protrusion 115 to the driven body 117 is represented by the vertical resistance, where the friction coefficient between the driven body 117 and the sliding protrusion 115 is μ1. As a result, the driving force transmitted by the left and right sliding protrusions 115 becomes unbalanced, and the efficiency of the ultrasonic actuator 100 is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic actuator with improved efficiency which overcomes the above-mentioned disadvantages of the prior art.

[0008]

According to the first aspect of the present invention,
A resonator, a plurality of electromechanical transducers fixed to the resonator, and an elliptical vibration generated in the resonator by applying a high-frequency voltage having a different phase to the electromechanical transducer. In an ultrasonic actuator that drives a driven member that presses against a body, a supporting position of the resonator when the driven member is pressed against the resonator is determined by a moment of reaction force based on a thrust of the ultrasonic actuator itself. This is the position where the occurrence is minimized.

According to a second aspect of the present invention, an elliptical vibration is applied to the resonator by applying a resonator, a plurality of electromechanical transducers fixed to the resonator, and high-frequency voltages having different phases to the electromechanical transducer. In the ultrasonic actuator that drives a driven member that presses the resonator based on the elliptical vibration, the support position of the resonator when the driven member is pressed against the resonator is determined by using the resonator In the vicinity of the driven body deviated from the position of the standing wave vibration node.

According to a third aspect of the present invention, an elliptical oscillator is applied to the resonator by applying a high-frequency voltage having a different phase to the resonator, a plurality of electromechanical transducers fixed to the resonator, and the electromechanical transducer. And an ultrasonic actuator that drives a driven member that presses against the resonator based on the elliptical vibration, wherein the support mechanism of the resonator when pressing the driven member against the resonator includes the resonator And a plate-like elastic member having a function of pressing a driven member against the resonator disposed on the lower end face of the plate.

[0011]

According to the ultrasonic actuator of the first aspect, when the driven member is pressed against the resonator, the supporting position of the resonator is changed by the moment of the reaction force based on the thrust of the ultrasonic actuator itself. Since the position is set to minimize the generation, the generation of the moment due to the reaction force based on the thrust of the ultrasonic actuator itself can be suppressed to the minimum only by the simple means of specifying the supporting position.

According to the ultrasonic actuator of the present invention, the position of supporting the resonator when the driven member is pressed against the resonator is shifted from the position of the standing wave vibration node of the resonator. Since it is located in the vicinity of the driving body, the generation of a moment due to a reaction force based on the thrust of the ultrasonic actuator itself can be suppressed to a minimum by the same simple means as in the first aspect of the present invention.

According to the ultrasonic actuator of the third aspect, the support mechanism of the resonator when pressing the driven member against the resonator is mounted on the resonator disposed on the lower end surface of the resonator. Since it is constituted by a plate-like elastic member which also has a function of pressing the drive member, the generation of a moment due to a reaction force based on the thrust of the ultrasonic actuator itself can be suppressed to the minimum, and the resonance The body can be held by a plate-like elastic member having a function of pressing the driven member, and the structure can be further simplified.

The operation of the present invention will be described below in more detail.
Hereinafter, the operation of the present invention will be described in more detail with reference to FIG. 12 again.

In FIG. 12, the ultrasonic actuator
Vertical resistance on the left and right sliding protrusions 116 due to thrust
Force W₁, W_TwoTo eliminate the imbalance of (L₁/ 2
・ L _Two) ・ F_RShould be close to zero.
Dimension L₁Should be close to zero. Specifically, the support position is
Dimension L₁So that the position of the sliding protrusion 116 is close to zero.
The position may be shifted in the Y direction shown in FIG. Ideally,
The sliding protrusion 116 is arranged at the height of the contact surface with the driven body 117.
Can eliminate the above imbalance when placed.
Wear.

[0016]

Embodiments of the present invention will be described below in detail.

[First Embodiment] A first embodiment will be described with reference to FIGS.
An embodiment will be described.

(Construction) The ultrasonic vibrator 6 of the first embodiment includes a brass substantially rectangular parallelepiped resonator 2 having a pair of electromechanical transducers 1 arranged therein .
As shown in FIGS. 4 and 5, the resonance longitudinal vibration shown in FIG. 4 and the resonance bending vibration shown in FIG. 5 are simultaneously excited.

A stainless steel pin 4 hardened at the center in the left-right direction and near the lower end of the resonator 1 is connected to the resonator 2.
Press-fit. At the center of the upper surface of the resonator 2, a projection 20 for fixing the electromechanical transducer 1 is formed integrally with a surface perpendicular to the resonator 2.

The electromechanical transducer element 1 is so pressed that the end face of the electromechanical transducer element 1 is pressed and stopped by the projection 20.
Is firmly fixed to the resonator 2 by the fixing member 21 and the screw 22. At the time of this fixing, an adhesive is applied to the entire surface of the electromechanical transducer 1 that is in contact with the resonator 2, thereby firmly fixing the resonator 2 of the electromechanical transducer 1. A sliding protrusion 5 is provided at a bending vibration antinode position on the side opposite to the surface on which the electromechanical transducer 1 is arranged.

FIGS. 1 and 2 show an example in which an ultrasonic linear actuator is formed by using the ultrasonic vibrator 6 having this configuration.

The pin 4 of the ultrasonic vibrator 6 is sandwiched in a V groove 8 of a hardened stainless steel holder 7, and a pressing spring 10 is provided above the V axis 8 of the holder 7 on a vertical axis 9. Is provided so as to be in contact with the upper surface of the holder 7, and the opposite of the pressing spring 10 is coupled to a pressing screw 12 screwed to the housing 11, and the pressing screw 12 is adjusted to be appropriately connected to the holder 7 through the holder 7. The pressing force is applied to the ultrasonic vibrator 6.

The side surface of the holder 7 is supported by bearing means 13 so that the holder 7 can move in the vertical axis 9 direction (C direction) without resistance. A sliding member 15 adhered and fixed to a driven body 14 is disposed on a surface of the ultrasonic vibrator 6 where the sliding protrusion 5 provided is in contact, and the driven body 14 is movably held by a bearing 16. ing.

[0024] (Operation) According to the first embodiment, determined the dimensions of the resonator 2 so as to match the resonance frequency of the longitudinal vibration and the second-order bending vibration of the primary of the resonator 2, the ultrasonic vibration By applying a drive voltage having a resonance frequency of the resonator 2 shifted by 90 degrees in phase from a high-frequency power supply (not shown) to the two electromechanical transducers 1 of the element 6, the adhesive is fixed to the antinode of the resonator 2 The driven sliding portion 5 performs an elliptical vibration, and the driven body 14 on the bearing 16 is driven linearly.

(Effect) By setting the press-fitting position of the pin 4 at the center of the resonator 2 in the left-right direction and near the lower end of the resonator 2, it is possible to reduce the dimension L shown in FIG. Thereby, the imbalance due to the thrust applied to the sliding protrusion 5 can be reduced with a simple configuration.

[Second Embodiment] FIGS. 6 to 8 show the second embodiment.
This will be described with reference to FIG. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

(Construction) In the center of the lower end face 17 of the resonator 2 of the ultrasonic transducer 25 shown in FIG.
8 is provided in such a size that its groove depth is equal to the thickness of the support spring 19, which is a plate-like elastic member, and that the support spring 19 enters the groove 18 without any groove width. A screw hole 24 for screwing a screw 23 for fixing the support spring 19 is provided at the center of the groove 18.

FIGS. 7 and 8 show the configuration of an ultrasonic linear actuator using the ultrasonic vibrator 25. FIG.

An end 27 of a holder 26 corresponding to the holder 7 having a structure in which a lower part is opened is provided with a screw 2
A screw hole corresponding to the hole 28 of the support spring 19 fixed by 3 is drilled, so that the ultrasonic vibrator 25 can be screwed through the support spring 19 to the holder 26 using the screw 29. To be fixed to At the upper end of the holder 26, a pressing screw 12 is arranged. Other configurations are the same as those of the first embodiment.

(Operation) According to the present embodiment, the pressing screw 12
By turning, the support spring 19 bends, and the pressing force of the driven body 14 against the sliding protrusion 5 can be given while fixing the ultrasonic vibrator 25.

(Effect) In the second embodiment, since the lower surface of the ultrasonic vibrator 25 is fixed, imbalance due to thrust can be further reduced, and the holding and pushing of the ultrasonic vibrator 25 by the support spring 19 can be achieved. The structure can be made simpler because it can also serve as pressure application.

It is obvious that the ultrasonic actuator of this configuration can be applied not only to the linear type but also to a rotary type ultrasonic actuator by pressing a rotating body against an elliptical vibration generating section.

[0033]

According to the first aspect of the present invention, the support position is set to a position where the generation of a moment due to a reaction force based on the thrust of the ultrasonic actuator itself is minimized.
The generation of a moment due to a reaction force based on the thrust of the ultrasonic actuator itself can be minimized by simple means. According to the second aspect of the invention, Ru can be suppressed the occurrence of moment due to the reaction force based on the thrust of the ultrasonic actuator itself invention similar simplified structure of claim 1, wherein a minimum. According to the invention 請 Motomeko 3 wherein, with the generation of the moment due to the reaction force based on the thrust of the invention similar to the ultrasonic actuator itself of claim 1, wherein it is possible to minimize, the use of the plate-like elastic member Can further simplify the structure.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an ultrasonic actuator according to a first embodiment of the present invention.

FIG. 2 is a schematic side view showing the ultrasonic actuator of the present embodiment.

FIG. 3 is a perspective view showing an ultrasonic vibrator in the ultrasonic actuator of the present embodiment.

FIG. 4 is an explanatory diagram showing longitudinal vibration of an ultrasonic transducer.

FIG. 5 is an explanatory diagram showing bending vibration of the ultrasonic transducer.

FIG. 6 is an exploded perspective view showing an ultrasonic transducer and a support spring in an ultrasonic actuator according to a second embodiment of the present invention.

FIG. 7 is a schematic sectional view showing an ultrasonic actuator according to a second embodiment of the present invention.

FIG. 8 is a schematic side view showing the ultrasonic actuator of the present embodiment.

FIG. 9 is a perspective view showing a conventional ultrasonic actuator.

FIG. 10 is an explanatory diagram showing longitudinal vibration of an ultrasonic transducer.

FIG. 11 is an explanatory diagram showing bending vibration of the ultrasonic transducer.

FIG. 12 is an explanatory diagram showing moment, thrust, and reaction force in a conventional ultrasonic actuator.

FIG. 13 shows a thrust in a conventional ultrasonic actuator,
It is explanatory drawing which shows a reaction force.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromechanical conversion element 2 Resonator 4 Pin 5 Sliding protrusion 6 Ultrasonic vibrator 7 Holder 8 V groove 10 Press spring 11 Housing 12 Press screw 13 Bearing means 14 Driven body

Continuation of the front page (72) Inventor Yoshihisa Taniguchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside the O-Limpus Optical Industry Co., Ltd. (72) Inventor Kazuhiro Kumei 2-43-2 Hatagaya, Shibuya-ku, Tokyo O-limpus (56) References JP-A-6-2844752 (JP, A) JP-A-6-254494 (JP, A) JP-A-4-347587 (JP, A) JP-A-2-228267 ( JP, A) JP-A-63-277477 (JP, A) JP-A-5-15693 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02N 2/00 B06B 1/06

Claims (3)

(57) [Claims] 1. A resonator, a plurality of electromechanical transducers fixed to the resonator, and high-frequency voltages having different phases applied to the electromechanical transducer to generate an elliptical vibration in the resonator. In an ultrasonic actuator that drives a driven member that presses against the resonator based on vibration, the support position of the resonator when pressing the driven member against the resonator is based on the thrust of the ultrasonic actuator itself. An ultrasonic actuator, characterized in that the position is such that the generation of a moment due to a reaction force is minimized. 2. A resonator, a plurality of electromechanical transducers fixed to the resonator, and high-frequency voltages having different phases applied to the electromechanical transducer to generate an elliptical vibration in the resonator. In an ultrasonic actuator that drives a driven member that presses against the resonator based on vibration, a supporting position of the resonator when pressing the driven member against the resonator is determined by setting a standing wave oscillator of the resonator. An ultrasonic actuator, characterized in that it is located near the driven body shifted from the position and at the center of the resonator in the left-right direction . 3. A resonator, a plurality of electromechanical transducers fixed to the resonator, and a high frequency voltage having a different phase applied to the electromechanical transducer to generate an elliptical vibration in the resonator. In an ultrasonic actuator that drives a driven member that presses against the resonator based on vibration, a support mechanism of the resonator when the driven member is pressed against the resonator is fixed to a lower end surface of the resonator. An ultrasonic actuator comprising a plate-like elastic member having a function of pressing a driven member against the resonator.