JPH076716Y2 - Cylindrical piezoelectric actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cylindrical piezoelectric actuator used for clamping an object or the like.

[Conventional technology]

Piezoelectric actuators have been used in various fields in recent years, but as a structure thereof, a bimorph type in which piezoelectric ceramics and a metal plate are laminated and a laminated type in which piezoelectric ceramics are laminated are generally used.

A cylindrical piezoelectric actuator has been considered as an application example of the above-mentioned laminated type (see Japanese Patent Laid-Open No. 61-15383). As shown in FIG. 4, the piezoelectric ceramics 11 having a cylindrical shape and the electrodes 12 having a cylindrical shape are laminated alternately. , 14 were formed. When electricity is applied between the external electrodes 13 and 14, the inner diameter is displaced in the direction of contraction as shown by the arrow.Therefore, if the shaft is inserted through the hole 15, the shaft can be clamped. It was

[Problems of conventional technology]

However, the conventional piezoelectric actuator 10 as described above is displaced only in the direction of clamping toward the hole 15, and is only applied as a clamp element.

[Means for Solving the Problems]

In view of the above, the present invention provides a cylindrical piezoelectric actuator in which each cylindrical piezoelectric ceramic is sequentially shifted in the axial direction and laminated.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

As shown in a perspective view in FIG. 1 (a) and a sectional view in FIG. 1 (b), the piezoelectric actuator 1 has cylindrical piezoelectric ceramics 2 and internal electrodes 3 alternately laminated, and each piezoelectric ceramic 2 is The holes are sequentially shifted in the axial direction, and have a substantially conical shape having holes 1a as a whole. Also, on the slope,
External electrodes 4 and 5 are formed.

As shown in FIG. 1 (c), the electrode lead-out structure of the piezoelectric actuator 1 is such that the inner electrodes 3 are exposed every other layer to form electrode lead-out portions 3a at positions where the outer electrodes 4 are formed. The external electrode 4 is formed so as to connect the parts 3a. In addition, at the position where the external electrode 5 is formed, the internal electrodes 3 that are not bonded to the external electrodes 4 are exposed every other layer and serve as electrode lead-out portions 3b. 5 is formed. After all, the internal electrodes 3 are electrically connected in parallel every other layer.

Each piezoelectric ceramic 2 is polarized in the thickness direction, and when a voltage is applied through the external electrodes 4 and 5, each piezoelectric ceramic 2 extends in the thickness direction. At this time, the piezoelectric actuator 1 as a whole is displaced so that the inner diameter d ₁ is contracted and the entire length t ₁ is contracted.

That is, when the piezoelectric actuator 1 of the present invention is energized, it is displaced obliquely toward the hole 1a as shown by the arrow in FIG. 1 (b), and can be applied to various applications as described later. You can do it.

Next, a method for manufacturing the piezoelectric actuator 1 will be briefly described. First, a ceramic raw material having a piezoelectric effect is formed into a tape shape, and a conductive paste such as Mo-Mn is applied as the internal electrode 3, and then it is wound into a cylindrical shape and sequentially laminated for each layer. Then, the whole may be baked and polarized by a usual method to form the external electrodes 4 and 5.

Actually, two 20 μm thick ceramic tapes are put together to form a cylindrical piezoelectric ceramic 2 and the thickness of the internal electrode 3 is about
The piezoelectric actuator 1 was manufactured by stacking 55 sheets having a thickness of 10 μm. The overall dimensions are as follows: inner diameter d ₁ is 5 mm, outer diameter d ₂ is 12 mm, length t ₁ is 5 mm, and length of piezoelectric ceramics 2 is t.
₂ was 3 mm, and the inclination angle α was 30 °. The displacement amount when a voltage of 50 V was applied to the piezoelectric actuator 1 was as follows.

When the inclination angle α is increased, the clamping force is slightly weakened, but the axial displacement amount is increased. Conversely, when the inclination angle α is decreased, the axial displacement amount is decreased but the clamping force is increased. Therefore, it suffices to have an appropriate inclination angle α depending on the intended use.

Next, an application example using the piezoelectric actuator 1 of the present invention will be described.

The negative actuator F shown in FIG. 2 is formed by vertically connecting a plurality of piezoelectric actuators 1. The negative actuator F is displaced in a contracting direction when energized. Since a normal laminated actuator is displaced in a direction in which it expands when energized, such a negative actuator F that is displaced in the opposite direction is highly useful. Actually, as shown in FIG. 2, ten piezoelectric actuators 1 are connected and the length t is 50 mm.
When a voltage of 50 V was applied to the above, the displacement amount of the length t was -12.3 μm.

The linear motor L shown in FIG. 3 (a) comprises a rotor 7 having two piezoelectric actuators 1A and 1B fixed in opposite directions, and a shaft 6 inserted through these piezoelectric actuators 1A and 1B. In this piezoelectric actuator 1A, 1B,
As shown in FIG. 3 (b), the AC voltage is changed in phase.
When applied with a 90 ° offset, the rotor 7 will drive on the shaft 6. This is the piezoelectric actuator 1A, 1B
Not only clamps the shaft 6, but also simultaneously displaces the shaft 6 so as to move the shaft 6 in the axial direction. Actually, the rotor 7 has an outer diameter of 12 mm, a length of 15 mm, the shaft 6 has an outer diameter of 5 mm, the piezoelectric actuators 1A and 1B have an inclination angle α of 30 °, and when an alternating voltage of 30 V is applied,
With a maximum frequency of 100 KHz, the maximum operating speed of the rotor 7 is 80
It was mm / sec.

[Effect of device]

As described above, according to the present invention, in the cylindrical piezoelectric actuator, the cylindrical piezoelectric ceramics are sequentially shifted in the axial direction so that the holes are clamped at the time of energization and simultaneously displaced in the axial direction. It can be used for various applications such as linear motors, and because it has no mechanical sliding parts, it can be displaced with extremely high precision.

[Brief description of drawings]

FIG. 1 (a) is a perspective view showing a piezoelectric actuator according to an embodiment of the present invention, FIG. 1 (b) is a sectional view taken along line XX in FIG. 1 (a), and FIG. It is a principal part expanded sectional view which shows a structure. FIG. 2 is a side view showing a negative actuator which is an application example of the present invention. FIG. 3 (a) is a cross-sectional view showing a linear motor which is another application example of the present invention, and FIG. 3 (b) is a diagram showing a waveform of an AC voltage supplied to the linear motor shown in FIG. 3 (a). is there. FIG. 4 is a sectional view showing a conventional cylindrical piezoelectric actuator. 1: Piezoelectric actuator 2: Piezoelectric ceramics 3: Internal electrode 4, 5: External electrode

Claims (1)

[Scope of utility model registration request] 1. A cylindrical piezoelectric actuator, characterized in that a plurality of cylindrical piezoelectric ceramics and electrodes are laminated alternately in a state of being axially shifted in sequence.