JPH06197560A - Actuator - Google Patents

Abstract

PURPOSE:To obtain an actuator having stabilized characteristics by improving the contacting state between a moving body and fixed member so as to reduce the occurrence of friction between them. CONSTITUTION:A moving body 3 and inertial body 4 are respectively fixed to both end faces of a laminated piezoelectric element 2. A guide member 7 utilizing the rolling of balls 6 is provided between the moving body 3 and a fixed member 5. The member 7 is constituted in such a way that two rails 8 are respectively fixed to the body 3 and member 5 and the balls 6 are put between two rails 8. The body 3 is finely moved by utilizing the impact force of the inertial body 4 by applying a voltage across the element 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator driven by using an electromechanical energy conversion element.

[0002]

2. Description of the Related Art As a conventional actuator of this type, one disclosed in, for example, JP-A-63-299785 is known. That is, the actuator is configured such that the metal moving body 12 is fixed to one end surface of the piezoelectric element 11 and the metal inertial body 13 is fixed to the other end surface thereof (see FIG. 1 of the publication). The moving body 12 contacts the surface of the fixed member (base 4), and the inertial body 13 does not contact the fixed member 4. When, for example, a voltage waveform (see FIG. 7 of the same publication) is applied to the piezoelectric element 11, the piezoelectric element 11 expands and contracts as shown in FIG. 3 of the publication, and the moving body 12 is slightly moved by the force associated with the rapid deformation of the inertial body 13. It is a thing. Further, as shown in FIG. 15 of the publication, there is also proposed a structure in which a bimorph type piezoelectric element 31 which is bent and deformed is used as a piezoelectric element, and a movable body 32 is minutely moved by a rapid deformation force of an inertial body 33.

[0003]

However, according to the above-mentioned conventional technique, the contact surface between the movable body and the fixed member is abraded, which is a serious problem. This contact surface has a great influence on a minute step movement, and an accurate step distance cannot be maintained due to a wear phenomenon, or a movement speed changes depending on a reversible direction.
Further, due to the generation of abrasion powder, the powder intervenes between the contact surfaces, causing a problem such as destabilizing the friction coefficient between the moving body and the fixed member.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to improve the contact state between a movable body and a fixed member, reduce the occurrence of wear, and stabilize the characteristics. The present invention provides an actuator.

[0005]

[Means for Solving the Problems] An actuator that is slightly moved by an impact force of an electromechanical energy conversion element, and includes a moving body fixed to one end surface of the conversion element and an opposite end surface of the conversion element. An inertial body to be fixed, a guide member installed between the movable body and the fixed member, and moved by a ball or a roller, and a pressing member installed on the movable body or the fixed member to apply a preload to the ball or the roller of the guide member. And an actuator are configured. The electromechanical energy conversion element is composed of a multi-layer piezoelectric element that is bent and displaced by stacking a large number of piezoelectric elements that are displaced in the thickness sliding direction.

[0006]

According to the above construction, between the moving body and the fixed member,
By installing the guide member that is preloaded by the pressing member, it is possible to eliminate wear between the moving body and the fixed member. Normally, guide members using balls and rollers are often used for bearings, etc., but if these are used as they are,
Since the rolling friction coefficient of balls and rollers is small, it is not possible to realize minute movement using impact force. For example, in the case of rapid deformation due to expansion and contraction of the electromechanical energy conversion element, since the stationary holding force of the moving body is small, the moving body moves during both expansion and contraction, making it difficult to obtain a stable step amount.
Also, the step amount becomes extremely small.

However, by preloading the balls and the rollers to increase the rolling friction coefficient, the movable body can be moved by the impact force of the inertial body accompanying the rapid deformation of the electromechanical energy conversion element.

The conventional coefficient of static friction between the moving body and the fixed member is a stable coefficient such as the rolling friction coefficient of a ball or a roller, and the step amount and the moving speed of the actuator can be made constant. In addition, there is no generation of abrasion powder.

[0009]

Embodiment 1 FIGS. 1 and 2 show an actuator of this embodiment, and as shown in FIG. 2 as an electromechanical energy conversion element, a large number of thin piezoelectric elements 1 which are displaced in the thickness direction by applying a voltage are laminated. The laminated piezoelectric element 2 that expands and contracts is used.

A movable body 3 made of metal is adhered and fixed to one end surface of the laminated piezoelectric element 2, and an inertial body 4 made of metal is similarly adhered and fixed to the other end surface. Mobile 3
Between the fixing member 5 and the fixing member 5, two guide members 7 utilizing rolling of the ball 6 are installed. The guide member 7 has rails 8 fixed to the movable body 3 and the fixed member 5, respectively, and a large number of balls 6 are installed between the two rails 8. The rail 8 on the fixed member 5 side is preloaded in the direction of the rail 8 on the moving body 3 side by a screw 9 that is a pressing member. When a voltage having a conventional pattern is applied to the laminated piezoelectric element 2, the moving body 3 is slightly moved by the impact force of the inertial body 4.

Explaining the operation of the actuator configured as described above, the rolling friction coefficient of the ball can be increased by the preload of the pressing member installed on the fixed member. When the impact force of the inertial body exceeds the rolling frictional force of the ball, the moving body moves in small steps. When the moving body moves, the sphere rotates and suppresses abrasion with the fixed member. In addition, even if it is reversibly moved, since the friction coefficient does not change depending on the direction, the moving speed becomes constant. Also, the amount of one step can be made variable by adjusting the preload of the pressing member.

In the actuator of this embodiment described above, wear is eliminated between the moving body and the fixed member, and the step amount and moving speed become constant. In addition, there is no generation of abrasion powder, and a long life can be realized.

[0013]

[Embodiment 2] FIGS. 3 and 4 show an actuator according to the present embodiment, and as shown in FIG. 4 as an electromechanical energy conversion element, a large number of thin piezoelectric elements which are displaced in the thickness sliding direction by voltage application are laminated. Laminated piezoelectric element 11
Is used. The laminated piezoelectric element 11 is bent and deformed by applying a voltage.

A metal moving body 3 is adhered and fixed to one end surface of the laminated piezoelectric element 11, and the other end surface is
The inertial body 4 made of metal is similarly fixed by adhesion. Between the moving body 3 and the fixed member 5, two guide members 7 utilizing the rolling of the ball 6 are installed as in the first embodiment described above.
Preload is applied by the screw 9 of the pressing member. The ball 6 and the rail 8 are coated with grease. When a voltage having a conventional pattern is applied to the laminated piezoelectric element 11, the laminated piezoelectric element 11 is bent and deformed, and the impact force of the inertial body 4 causes the moving body 3 to move minutely.

The operation of the actuator configured as described above will be described. Using the bending deformation of the piezoelectric element,
A device using a bimorph type piezoelectric actuator has been proposed as a device for slightly moving a moving body. However, since a bimorph has a small generating force, a large moving body cannot move. Also, a large voltage is required to obtain a sufficient step amount. However, when the bending deformation of the laminated piezoelectric element as in this embodiment is used, a large generated force can be obtained and a small step drive can be realized with a small mechanism. Further, it is possible to apply grease to the guide member and further suppress abrasion. Also, the pronunciation when moving can be reduced.

In the actuator of this embodiment described above, the same effect as that of the first embodiment can be obtained even if the bending deformation of the laminated piezoelectric element is used. It should be noted that, if a laminated piezoelectric element that expands and contracts and is used in Example 1 is added to the moving body, a large step amount and high speed movement can be realized.

[0017]

Third Embodiment FIGS. 5 and 6 show an actuator according to the present embodiment, which is an example of an actuator that moves in a minute rotation. As the electromechanical energy conversion element, the bending-type laminated piezoelectric element 11 similar to that of the second embodiment is used.

A ring-shaped moving body 12 is adhered and fixed to one end surface of the laminated piezoelectric element 11, and a metal inertial body 4 is similarly adhered and fixed to the other end surface.
A ring-shaped guide member 14 utilizing the rolling of the ball 6 is installed between the moving body 12 and the disc-shaped fixed member 13. The guide member 14 includes the movable body 12 and the fixed member 1.
The rails 15 are fixed to 3 and the two rails 15
A large number of spheres 6 are installed via a retainer 16 between them. In addition, on the rail 15 on the side of the moving body 12,
Preload is applied in the direction of the rail 15 on the side of the fixing member 13 (outer direction from the center) by the screw 9 which is a pressing member. When a voltage having a conventional pattern is applied to the laminated piezoelectric element 11, the moving body 12 is finely rotated by the impact force of the inertial body 4.

The operation of the actuator constructed as described above will be described. By using a bending-deformable laminated piezoelectric element, minute rotational movement can be realized. Also in this case, since the rolling of the ball is used, the abrasion does not occur and the step movement of a certain angle can be performed in the reversible rotation direction.

The actuator of the present embodiment described above is an example in which the impact force of the inertial body is used for the rotational movement, but it is possible to achieve a minute rotational movement with a very simple structure and to achieve miniaturization.

In the first, second and third embodiments, the guide member for rolling with a sphere has been shown, but the guide member using the rolling of the roller 17 as shown in FIG. .

[0022]

In the actuator of the present invention, a preloaded sphere or roller guide member is installed between the moving body and the fixed member to prevent the friction coefficient from changing due to wear, and to change the step amount and the movement. It is possible to provide an actuator that can obtain a stable speed.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an actuator according to a first embodiment of the present invention.

FIG. 2 is a stacking state diagram of piezoelectric elements according to the first embodiment.

FIG. 3 is a schematic diagram of an actuator according to a second embodiment of the present invention.

FIG. 4 is a stacking state diagram of piezoelectric elements according to the second embodiment.

FIG. 5 is a schematic diagram of an actuator according to a third embodiment of the present invention.

FIG. 6 is a sectional view of an actuator according to the third embodiment.

FIG. 7 is a sectional view of an actuator of a modified example of the invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thickness direction piezoelectric element 2 Stretching laminated piezoelectric element 3 Moving body 4 Inertial body 5 Fixing member 6 Sphere 7 Guide member 9 Pressing member 10 Thickness sliding direction piezoelectric element 11 Bending laminated type piezoelectric element

Claims (2)

[Claims] 1. In an actuator that is slightly moved by an impact force of an electromechanical energy conversion element, a movable body fixed to one end surface of the conversion element and an inertia fixed to the other end surface of the conversion element facing each other. A body, a guide member that is installed between a movable body and a fixed member, and is moved by a ball or roller, and a movable body or a fixed member,
An actuator comprising: a pressing member that applies a preload to a ball or a roller of the guide member. 2. The actuator according to claim 1, wherein the electromechanical energy conversion element is a laminated piezoelectric element in which a large number of piezoelectric elements that are displaced in the thickness sliding direction are laminated and bent and displaced.