JPH10337051A - Oscillatory actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of the shaft member for an oscillatory actuator, e.g. a rod-like oscillation wave motor. SOLUTION: The oscillatory actuator comprises an oscillator for clamping a piezoelectric element 3 by resilient bodies 1, 2 and tightening the resilient bodies 1, 2 by means of a shaft member 5 passing through the central part of these members, and a contacting body 8 moving relatively to the oscillator while touching the driving face of the resilient body 1. The shaft member 5 comprises a flange part 5a having a larger diameter than other part, and a threaded part being screwed with a tightening nut member 6 wherein the piezoelectric element 3 and the first resilient body 2 are clamped by the flange part 5a and the nut member 6 being tightened to the threaded part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration type actuator such as a vibration wave motor.

[0002]

2. Description of the Related Art A strain generating element as an electro-mechanical energy conversion element that generates mechanical strain in response to the action of an electric field or a magnetic field is attached to an elastic body to form a vibrating body. Vibration wave actuators that vibrate a body and convert the vibration of the elastic body into continuous or intermittent mechanical movement and output the vibration wave actuator are currently used in various fields. Piezoelectric / electrostrictive actuators utilizing electrostrictive elements are most widely used.

[0003] Among the piezoelectric actuators using the piezoelectric element, an actuator called a vibration wave motor can constitute a continuous rotation type rotary drive source. And so on.

[0004]

Various types of vibration wave motors have been proposed. Vibration wave motors currently being manufactured are roughly classified into the following. 1) A flat or ring-shaped elastic body There is a flat type that excites a vibration wave and presses the disk-shaped or ring-shaped rotor against it, and a 2) rod-type (so-called pencil type) that presses the rotor against the Langevin type vibrator. .

FIG. 9 shows a conventional ring-shaped vibration wave motor as an example of such a vibration wave motor. The vibration wave motor corresponds to an elastic body 20 supported by a case 24 and forming a ring-shaped vibration body together with a piezoelectric element 25. The rotor 21 rotating integrally with the output shaft 22 is in pressure contact with the disc spring 23.

One of the major problems of the vibration wave motor represented here is that the cost is high. In a traveling wave type vibration wave motor, 1) in order to match (close as much as possible) the resonance frequencies of two different vibration modes, the shape accuracy of the ring-shaped elastic body is strictly controlled (from several μm to several μm). 10 μm), so it is absolutely necessary to rely on machining, and mass production processing such as forging, powder sintering, and pressing cannot be used easily. 2) The cost of the piezoelectric element is high (particularly, large-diameter ring-type vibrators). In that, there are many parts to throw away material, attaching electrodes,
There are many post-processes such as polarization.) 3) There is a bonding process for the piezoelectric element. (Motor performance is greatly affected by the quality of bonding, so pay close attention to cleaning of the bonding surface, surface accuracy, bonding conditions, etc.) ).

Instead of this, as shown in FIG. 8, a rod-shaped vibration wave motor which is advantageous in cost has been proposed.

In this vibration wave motor, a plurality of PZTs 3 and a power supply electrode plate are sandwiched between a first elastic body 1 and a second elastic body 2 having a hole coaxial with the outer diameter at the center. The male screw portion of the shaft 5 having the holes penetrated is screwed into the inner screw portion 1 e of the elastic body 1, and PZT3
The Langevin type vibrating body is formed by tightening the elastic bodies 1 and 2 with the interposed members.

On the other hand, around the shaft 5, a rotor 8 which engages with the gear 11 and abuts on the spring case 9 in the thrust direction, a spring case 9 in which a pressure spring 14 is provided, and a shaft rotatably mounted on a ball bearing 10. Supported gear 11,
A motor mounting flange 12 on which the ball bearing 10 is mounted is disposed.
Is fixed by a nut member 13. The spring force of the pressure spring 14 is transmitted to the rotor 8 via the spring case 9,
It comes into pressure contact with the driving surface of the elastic body 1. The rotational force is transmitted to the gear 11 and output to the outside.

When an alternating signal, for example, a frequency voltage, which is a driving signal, is applied to the PZT 3, a driving wave is formed on the driving surface of the first elastic body 1 by synthesizing bending vibration, and the driving wave causes the rotor 8 to generate friction. Driven.

The rod-shaped vibration wave motor shown in FIG. 8 can be reduced in diameter (the piezoelectric element can be laminated, so that input power can be supplied even if the motor is reduced in diameter). Such a structure is suitable for low cost, and in fact, a considerable cost reduction can be realized as compared with the vibration wave motor of the type shown in FIG.

However, the cost is several times higher than that of a small electromagnetic motor when compared at the same output, and the characteristics (for example, quietness, direct drive, and holding power) of the vibration wave motor are sufficient. The fact is that it is used only in limited fields where it can be used.

In the future, in order for a vibration wave motor to be put to practical use in a wide range of fields, it is indispensable to reduce the cost until it becomes comparable to an electromagnetic motor, and this is a major problem.

An object of the present invention is to further improve a vibration type actuator such as a rod type vibration wave motor.

[0015]

According to a first configuration for realizing the object of the present invention, an electro-mechanical energy conversion element is sandwiched between a first elastic body and a second elastic body from both sides. A vibrating body in which the first elastic body and the second elastic body are tightened from both sides by a shaft member passing through a center portion of the member, and a driving surface of the first elastic body which is in contact with the vibrating body; In a vibration-type actuator having a moving contact body, the shaft member has a flange portion having a larger diameter than other portions, and a screw portion screwed to a tightening nut member. The energy conversion element and the first and second elastic bodies are sandwiched between screwed nut members.

A second configuration for realizing the object of the invention according to the present application is the above-mentioned first configuration, wherein the shaft has a first shaft portion for holding the vibrating body and the second portion except for the flange portion. And a second shaft portion having a smaller diameter than the one shaft portion.

A third configuration for realizing the object of the present invention according to the present application is the above-described first and second configurations, wherein the second shaft portion is constituted by a plurality of step portions having different diameters. is there.

A fourth structure for realizing the object of the invention according to the present application is the first, second or third structure, wherein the shaft member is formed by header processing and rolling. .

A fifth configuration for realizing the object of the invention according to the present application is the above-mentioned first, second, third or fourth configuration.
An open side surface of at least one of the flange portion of the shaft member and the screw member is formed as a concave or convex surface which becomes a resistance when tightening a screw by contact with a jig.

A sixth configuration for realizing the object of the invention according to the present application is the fifth configuration, wherein the concave and convex portions formed on the flange portion of the shaft member are inclined in a direction that provides resistance when screwing. This is a serration.

In the above configuration, 1) the internal thread portion 1e cut into the first elastic body 1 in the conventional example shown in FIG. 8 can be eliminated, and the processing cost can be reduced.

2) Also, by eliminating the inner screw portion 1e, the first elastic body can be formed by die casting or the like.

3) By forming a concave portion or a convex portion on the open side surface of the flange portion or the nut portion member of the shaft member, even if the diameter of the flange portion is small, the tightening jig and the flange portion and the nut member can be tightened without slipping. As a result, the difference between the maximum diameter and the minimum diameter of the shaft member can be made smaller than in the conventional example, and a processing method suitable for mass production, such as header processing and rolling processing, is adopted.

This makes it possible to reduce the cost,
The problem can be solved.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.

A laminated PZT 3 and a power supply flexible 4 are sandwiched between a first elastic body 1 and a second elastic body 2 each having a hole coaxial with the outer diameter at the center thereof, and the holes penetrate through these holes. The Langevin-type vibrating body is formed by tightening the above-mentioned members 1 to 4 with the flange portion 5a of the shaft 5 and the nut 6 thus formed. Further, a friction ring 7 (SUS420J2 quenched product) is joined to the upper part of the first elastic body 1 in the figure by an adhesive.

On the other hand, the aluminum rotor 8 is subjected to alumite treatment, and is joined to an iron-based metal spring case 9 by an adhesive or the like. The spring case 9 is provided with a cylinder portion for guiding the spring and a flange portion for receiving the spring below the cylinder portion. The compression spring 14 is sandwiched between the flange portion and the lower portion of the gear 11, and compressed. The rotor 8 is pressed against the friction ring 7 of the vibrator.

The gear 11 is positioned in the thrust direction by a motor mounting flange 12 positioned by a positioning step 5k provided on the shaft 5 and a nut 13 for fixing the gear 11 via a ball bearing 10. And is rotatably supported by a ball bearing 10.

The driving of the vibration wave motor having the above-described configuration is performed by transmitting a two-phase alternating signal out of phase from a power source (not shown) to the laminated PZT3.
, Bending vibrations in two directions with respect to the longitudinal direction of the shaft 5 are excited by the vibrating body, and the vibrating body performs a skipping motion. At this time, an elliptical vibration occurs on the sliding surface of the friction ring, whereby the rotor 8, the spring case 9, the gear 11
Rotates together. The spring case 9 is provided with two grooves (not shown) in the radial direction, and the two protrusions (not shown) provided on the gear 11 are fitted without any gap. The torque of the rotor 8 is transmitted to the gear 11 without loss.

In this embodiment, the shaft is manufactured by cutting SK4F material (free-cutting material). However, since the maximum diameter of the shaft is smaller than that of the conventional example (φ7.6 of the conventional example).
mm → 5a section φ3.8 mm) Since the machining allowance is small, the machining cost can be reduced to about 2/3 of the conventional cost. Also, as for the vibrating body 1, the number of processing steps for cutting was remarkably reduced because the internal thread portion was eliminated, and the processing cost was reduced to about １ ／. Furthermore, as a result of eliminating screws, the shape becomes die-castable, and by using die-casting materials such as zinc and aluminum, the cost is reduced to half that of cutting.
It can be reduced to １ ／.

In the present embodiment, the flange portion 5a of the shaft is located near the center of the shaft, and a nut is screwed to the end of the shaft. The structure (5a in FIG. 1) may be tightened with a nut.

(Second Embodiment) FIGS. 2 and 3 show a second embodiment.

FIG. 2 is a sectional view of the rod-shaped vibration wave motor, and FIG. 3 is a plan view of the shaft of FIG.

In this embodiment, the shaft 5 is formed by header processing, and a flange 5a is provided near the center.
Screw portion 5b at the tip of the large-diameter side shaft portion (A portion)
And the screw 5c at the tip of the small diameter side shaft portion (B portion) and the positioning portion 5d of the motor mounting flange 12 were formed by rolling.

Header processing is a kind of plastic processing using a forging die, and is often used for processing bolts, shafts, and the like. In this embodiment, as shown in FIG. The long wire a wound into a shape is cut into an appropriate length by a header processing machine b, and this is used as a blank c.

Further, a punch (1P, 2P, 3P, etc.) and a die (1D, 2D, etc.) are prepared in the header processing machine b, and are roughly formed in the first step (combination of the punch 1P and the die 1D). In order to perform the above, the blank c is compressed (extruded) from the rough forming punch 1P side to form a thin pin having a step. In the second step, a molded product indicated by oblique lines formed in the first step is molded by the second punch P2 and the second die D2, and the molded article in the second step is formed in the third step. In the above, a punch P3 and a die D2 are used for forming, and these steps are sequentially performed to gradually form a final product.

In this embodiment, the material of the shaft is SCM.
After rolling, quenching and tempering were performed so that the hardness became HRC 40 or more, and NiP plating was performed for rust prevention.

Although the same applies to the first embodiment, the shaft has four main roles.

First, part A is made of elastic bodies 1 and 2 and PZT.
3. To clamp the flexible member 4 with a strong clamping force using the nut 6 to form a rod-shaped vibrator. In order to realize a highly efficient vibrating body, the magnitude of the clamping force is an important parameter, and it is essential to maintain the strength of the portion A sufficiently.

In the present embodiment, the outer diameter of the vibrating body is φ10 m.
m, so that the A part has an axial force of 2
It was necessary to tighten with a force of 00 kgf or more. Therefore, part A is made φ2.3 mm, and HRC4 is used to increase the axial strength.
0 or more quenching was performed. Further, in order to increase the tensile and torsional rupture strength generated on the shaft when the nut is tightened, the diameter of the threaded portion 5b at which the shaft diameter is minimized is increased in order to increase the valley diameter. I was fine.

The second role is that the portion B functions as a motor support portion so as not to transmit the vibration of the portion A to the motor flange 12. For this purpose, the portion B is designed to be thinner than the portion A and to adjust the length appropriately to optimize the bending rigidity so as not to hinder the vibration of the portion A. In FIG. 3, the diameter of the 5h portion is φ1.4 mm, and the length of the B portion is 1
It was 3.2 mm.

The third role is to position the motor flange, thereby setting the amount of compression of the rotor pressure spring,
There is a function to set the pressing force. For this purpose, a positioning abutment 5d is provided on the shaft. Since the motor mounting flange 12 is inserted from the 5c side, the outer diameter of 5d must be larger than the maximum diameter of 5c. In order to greatly increase the 5d portion by rolling, the 5e and 5f portions are crushed and made finer, and the extra thickness is brought to the 5d portion, and the shape of the abacus is increased in order to efficiently increase the diameter of the 5d portion. I made a ball.

As a fourth role, the screw portion 5c has a function of engaging with the motor mounting flange 12 without play and determining the degree of rotation between the flange and the shaft 5. This flange 12
Is an important part for engaging with the gear 11 and the rotor 8 and maintaining the accuracy of the coaxiality of these parts.

(Third Embodiment) FIG. 4 shows a third embodiment.

In this embodiment, the diameter of the portion B is 5h, 5i
By adjusting the diameter and length of this portion in two steps as described above, the portion B was designed to have an optimal support function.

The length of the portion B is limited by the size of the motor and is not a parameter that can be changed so much.

In this embodiment, the 5i portion is φ1.4 m
m, length 1.8 mm, 5 h portion was φ1.2 mm, and these boundaries were tapered at 15 degrees to facilitate drawing.
The total length is 1 as in the second embodiment shown in FIG.
It was 3.2 mm.

As a further merit of forming a step on the shaft as described above, a two-step drawing can be performed at the time of header processing, so that the 5h portion can be further narrowed. Normally, in the case of a material such as SCM435 which is high carbon and hard as in the present embodiment, the shape of the shaft according to the second embodiment shown in FIG.
Although the limit was about 1.6 mm, in the present embodiment shown in FIG. 4, φ1.2 mm could be realized, and the degree of freedom in designing the portion B was widened.

In the present embodiment, the portion B is provided in two stages. However, the present invention is not limited to this, and any portion may be formed in order to optimize the support function.

(Fourth Embodiment) FIG. 5 shows a fourth embodiment.

In this embodiment, a serration 5j having a groove depth of about 0.2 mm and 12 peaks is provided on the B side of the flange 5a at the center of the shaft. This is to make the serrations engage with the jig when assembling the vibrating body to facilitate the assembling. Hereinafter, a method of assembling the vibrator will be described.

As described above, the vibrating body has a structure in which the laminated PZT 3 and the flexible member 4 are sandwiched by the elastic members 1 and 2 and these members are fastened by the flange 5a and the nut 6 of the shaft. At this time, FIG.
As shown in the figure, two opposed chamfers 1a, 1b and 1
c and 1d, which need to be positioned so that they are orthogonal to the vibration direction of the first vibration mode. In addition, since the laminated PZT 3 and the flexible 4 have an electrode relationship, the relative positional relationship is determined.

That is, the relative positional relationship between the elastic body 1, the laminated PZT 3, and the flexible member 4 is determined. If the relative positional relationship is shifted during the assembly of the vibrating body, the performance of the vibrating body is significantly reduced.
Since the vibrating body of the conventional example (FIG. 8) has a thread cut into the elastic body 1, the outer peripheral part of the elastic body 1 is clamped at the time of assembly, and PZT
3. A jig for engaging the outer diameter of the elastic body 2 is used to determine the coaxiality of these components, and the shaft 5 is inserted from the elastic body 2 side while lightly pressing the end surface of the elastic body 2 toward the elastic body 1.
Was screwed into the elastic body 1 and tightened with a required torque. The reason why the end surface of the elastic body 2 is lightly pressed is to prevent the elastic body 2 from rotating due to the frictional force with the bearing surface of the shaft when the shaft is screwed, and to prevent PZT or the like from being shifted together.

However, in this embodiment, since the shaft and the elastic body 1 are fitted with a play, it is not possible to hold the elastic body 1 during assembly. Therefore, as shown in FIG. 6, the shaft is turned upside down, and the serration portion 5j of the shaft flange is engaged with the jig (the serration is also applied to the jig so that the jig also matches the shaft), and the elastic body 1, PZT3, flexible 4. By inserting the elastic body 2 into the shaft 5 as shown in the figure and tightening the nut 6 while applying a preload in the D direction by the jigs 16a and 16b, the shaft is prevented from rotating together when the nut is tightened. As a result, the assembly workability was improved.

Here, the serrations 5j are inclined in such a direction as to increase the catching force when the nut 6 is tightened, and although not shown in the drawing, the coaxiality of each of the members 1 to 4 is set. Needless to say, the assembly is also performed using a jig for putting out.

As the serrations 5j, as shown in FIG. 5C, the serrations may be iris knurls. In this case, the same knurls are applied to the shaft receiving surface of the assembly jig 15 at the same time. Further, as another example, although not shown in the drawing, the same effect can be obtained by roughening the uneven surface to a surface roughness of about 5 to 20S instead of the serration 5j as the uneven surface.

In this embodiment, only the SK4F material and the SCM435 are described as the material of the shaft. However, the material is not limited to these materials, and a metal material or a polymer material such as a reinforced plastic may be used. However, in the case of performing header processing and rolling processing, a material having ductility and toughness is preferable. For example, chromium molybdenum steel (SC
M415, SCM445, etc.), nickel chromium molybdenum steel, brass (73 series), stainless steel (SUS30
4), carbon steel (such as S45C), titanium, and heat-resistant steel (such as Inconel) have excellent workability. In particular, when strength is required for the shaft, a material that can be hardened is desirable.

[0058]

As described above, the first to sixth aspects of the present invention have the following effects.

1) Since the thread portion of the elastic body can be eliminated, the man-hour for processing the vibrating body can be greatly reduced, and the cost of the vibrating actuator can be greatly reduced.

2) By providing the flange portion or the nut member of the shaft member with a concave or convex so as to resist rotation, a sufficient tightening torque can be applied even if the diameter of the shaft flange is small. The difference between the maximum diameter and the minimum diameter of the shaft member can be reduced, and the number of processing steps can be reduced, so that the cost of the shaft member can be reduced.

3) The shaft member can be formed by header processing and rolling processing, and the cost of the shaft member can be further reduced.

4) Providing steps with different thicknesses on the small-diameter shaft portion of the shaft member facilitates the design of an optimal support shape without restriction on the length of the shaft member.

[Brief description of the drawings]

FIG. 1 is a sectional view of a vibration wave motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a vibration wave motor according to a second embodiment of the present invention.

FIG. 3 is a side view of the shaft of FIG. 2;

FIG. 4 is a side view of a shaft according to a third embodiment of the present invention.

5A and 5B show a fourth embodiment of the present invention, in which FIG. 5A is a side view of a shaft, FIG. 5B is an enlarged view of a shaft flange, and FIG.

FIG. 6 is a sectional view showing an assembled state of the vibrating body.

FIG. 7 shows a first elastic body, (a) is a plan view, (b)
FIG. 3A is a cross-sectional view along the line FF ′ in FIG.

FIG. 8 is a sectional view of a conventional vibration wave motor.

FIG. 9 is a sectional view of a conventional ring-type vibration wave motor.

FIG. 10 is a diagram showing header processing according to the second embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st elastic body 2 ... 2nd elastic body 3 ... Laminated PZT 4 ... Flexible (flexible printed wiring board) 5 ... Shaft 6 ... Nut 7 ... Friction ring 8 ... Rotor 9 ... Spring case 10 ... Ball bearing 11 ... Gear DESCRIPTION OF SYMBOLS 12 ... Vibration wave motor flange 13 ... Nut 14 ... Spring 15 ... Assembly jig 16 ... Assembly jig 17 ... Assembly jig 20 ... Vibration body 21 ... Rotor 22 ... Shaft 23 ... Pressure spring 24 ... Vibration wave motor cover

Claims (6)

[Claims] An electro-mechanical energy conversion element is sandwiched between a first elastic body and a second elastic body from both sides, and the first elastic body and the second elastic body are sandwiched by a shaft member passing through a central portion of these members. A vibrating body that tightens the body from both sides,
In a vibration-type actuator having a contact body that comes into contact with a driving surface of the first elastic body and moves relatively to the vibration body, the shaft member includes a flange portion having a larger diameter than other portions, and a tightening nut. A screw portion to be screwed to the member,
A vibration-type actuator, wherein the energy conversion element and the first and second elastic members are sandwiched between the flange portion and a nut member screwed to the screw portion. 2. The first shaft portion for holding the vibrating body on the shaft and the first shaft portion except for the flange portion.
The vibration type actuator according to claim 1, further comprising a second shaft portion having a smaller diameter than the shaft portion. 3. The vibration-type actuator according to claim 1, wherein the second shaft portion includes a plurality of steps having different diameters. 4. The vibration type actuator according to claim 1, wherein the shaft member is formed by header processing and rolling processing. 5. A flange portion of the shaft member or at least one open side surface of the screw member is formed as a concave or convex surface which becomes a resistance at the time of screw tightening by contact with a jig. The vibration type actuator according to claim 1, 2, 3, or 4. 6. The vibration-type actuator according to claim 5, wherein the concave and convex portions formed on the flange portion of the shaft member are serrations provided with an inclination in a direction that becomes a resistance at the time of screw tightening.