JPS61185079A - Piezoelectric linear motor - Google Patents

Abstract

PURPOSE:To enhance energy efficiency with a simple structure by driving a piezoelectric actuator with polyphase AC, and transmitting the displacements of the actuators magnetically to a movable element. CONSTITUTION:A piezoelectric motor has a movable elements 1, 6 bimorph type actuators 2 disposed oppositely to the element 1, and a stator frame 3. The actuators 2 vibrate when 3-phase power sources V1-V3 are applied, and the poles 6 at the end vibrate in response to the phase of the applied power by the application of 3-phase power source V1-V3. The vibration is transmitted magnetically to the element 1, and the element 1 linearly moves. The element 1 has a plurality of poles 5 disposed at the prescribed interval along the moving direction, and the actuators 2 have poles 6 opposed to the element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a piezoelectric linear motor, in particular a piezoelectric actuator such as a bimorph actuator and a ferromagnetic material. Regarding the motor that made this possible.

(Background of the invention) Conventionally, as a near motor using piezoelectric elements, the one disclosed in Japanese Patent Application Laid-Open No. 53-82286 is known. This linear motor uses two piezoelectric elements and a hook mechanism. The hook mechanism converts the vibration of the piezoelectric element into linear motion.However,
Since this motor uses a hook mechanism, the structure is complicated, the movable element may be in a free state, and the hook portion is worn out, resulting in low reliability. In addition, there is an inconvenience that precision machining of the hook portion is required, which increases the price of the product.

(Summary and Object of the Invention) In view of the problems with the conventional type described above, the present invention is a piezoelectric linear motor in which a piezoelectric actuator such as a bimorph actuator is driven with multiphase alternating current, and the displacement of the actuator is magnetically controlled. Based on the concept of transmitting power to the mover, the aim is to increase energy efficiency with a simple structure, reduce the size and weight of the motor, and improve reliability.

(Explanation of Examples) Hereinafter, the present invention will be explained in detail with reference to the drawings.

1(a) and (b) are a plan view and a perspective view, respectively, of a piezoelectric linear motor according to an embodiment of the present invention.The piezoelectric motor shown in these figures has a movable element 1,
For example, six bimorph type actuators 2 are arranged facing the movable element 1, and a fixing frame 3 for fixing each bimorph type actuator 2 at a predetermined position is provided. Further, 4 is a shaft of the movable element 1. Three bimorph actuators 2 are arranged on both sides of the movable element 1, and each has a magnetic pole 6 of, for example, a permanent magnet at the end on the movable element 1 side. Further, the movable element 1 has, for example, six magnetic poles 5 on both sides on which the bimorph actuator is arranged. The magnetic pole 5 is made of ferromagnetic material, and the other parts are made of non-magnetic material.

In the above-mentioned motor, each bimorph actuator that constitutes the stator is generally driven by a power source such as a sine wave or triangular wave of two or more phases of polyphase AC, and the magnetic pole spacing of the mover is d, and the number of phases of the polyphase AC is When p is the distance between bimorph actuators, (1) +Ill /n
)d/11. However, l.

n is a positive integer.

FIG. 2 shows a switch circuit for supplying three-phase power to the piezoelectric motor of FIG. 1. FIG. The circuit shown in the figure includes a switch S W + for moving and stopping the motor, and a switch S W 2 for switching the direction of movement of the motor. Three-phase power is applied to each bimorph actuator 2 as power supplies V+, V2, and V3 via these switches SW2 and SW+. When the switch S W 2 is in the reverse position, two of the three lines of the input three-phase power supply are connected interchangeably.

In the motor described above, when three-phase power supplies V+, V2, and V3 are applied to each bimorph actuator, each bimorph actuator vibrates according to the phase of the applied power supply, and this movement is caused by magnetic movement of the movable member. The movable element performs a linear motion.

FIG. 3 shows the positional relationship between the magnetic poles of the mover 1 and the magnetic poles of each bimorph type actuator. In the same figure, each point 6
a, 6b, and 6c are the positions of the actuator tips, the line segments are the movement trajectories of each tip, and the points 5a, 5b,
..., 5e each indicate the center position of the magnetic pole of the mover.

It is assumed that each bimorph actuator is driven by, for example, a three-phase power supply under the initial conditions shown in FIG. 3, that is, in a state in which points 5a and 68 face each other.

Since the initial point 5a is attracted to the point 6a, it moves in the direction indicated by the arrow X in the figure in response to the vibration of the point 6a, but since the distance between the two gradually increases, the attracting force changes in the direction of becoming weaker.

In response to this, the point 6C driven with a phase difference of 2π/3 attracts the approaching point 5d and moves the movable element in the arrow x direction. As a result, the point 5a escapes from the range of the force of the point 6a. Next, in the same way, point 6b attracts the approaching point 5b and moves the movable element in the direction of arrow x. By repeating these operations, the direct motion of the mover is maintained.

The results of an experiment conducted to confirm the operation of the piezoelectric linear motor having the above configuration will be described below. The mover 1 was constructed by adding five permanent magnet magnetic poles to a brass base, and the distance between each magnetic pole was set to 1.26 mm, which is about twice the amplitude of 0.6 mm of the bimorph type actuator. Three bimorph actuators made of lead titanium zirconate are used as stators, and a pure iron magnetic pole is attached to the tip of each actuator. The spacing between each bimorph actuator was 2.09 nun, and the spacing between the magnetic force between the mover and the stator was O.lli. A three-phase power supply V+ is applied to each bimorph actuator of such a piezoelectric motor.
, V2, V3 and LT20V, 100 Hz (7
) When a voltage was applied, a moving speed of about 126 ml1+7 seconds was obtained.

Moreover, FIG. 4 shows the relationship between displacement and time of such a piezoelectric linear motor. In the figure, F represents the force in the opposite direction applied in the axial direction, that is, the magnitude of the load in duram weight units. As is clear from Fig. 4, when the load is zero, that is, F=O, it operates normally whether driven by a triangular wave power supply or a sine wave power supply, but the load increases, for example, when F-=6. It is gram heavy and is inoperable when driven by a triangular wave power source.

Note that although the above description has been made regarding the case where a piezoelectric actuator is used for the stator, it is clear that the present invention can also be applied to a case where an electromagnetic actuator that performs a vibration operation similar to that of a piezoelectric actuator is used.

(Effects of the Invention) As described above, according to the present invention, a near motor with high energy efficiency can be realized with a relatively simple structure. In addition, since the moving speed of the mover is synchronized with the input signal, it is possible to accurately control the moving speed, etc., and it is also possible to adjust the moving speed over a wide range by changing the frequency of the drive power source. becomes. moreover,
Reverse movement is also possible. In addition, there is little magnetic leakage, and a small metering linear motor can be realized.

Furthermore, since the input impedance is increased, the load on the drive circuit can be reduced.

[Brief explanation of drawings]

1 (a>F3 and (b) are respectively a plan view and a perspective view of a piezoelectric linear motor according to an embodiment of the present invention,
Figure 2 is an electric circuit diagram showing the switch circuit connected to the motor in Figure 1, Figure 3 is an explanatory diagram showing the operation of the motor in Figure 1, and Figure 4 shows the characteristics of the motor in Figure 1. This is a graph showing. 1: Mover, 2: Bimorph actuator, 3: I
IA fixed frame, 4 left, 5. 6:1iil pole, SW
+, SW2: Switch.

Claims (4)

[Claims] 1. A stator comprising a movable element having a plurality of magnetic poles arranged at predetermined intervals along a moving direction, and a plurality of piezoelectric actuators each disposed at a predetermined interval opposite the movable element and having magnetic poles on the movable element side portion. Each piezoelectric actuator is driven by a multiphase alternating current power source, and the magnetic poles added to each piezoelectric actuator are vibrated substantially along the moving direction of the movable element, thereby causing linear motion in the movable element. Features a piezoelectric linear motor. 2. The magnetic pole spacing of the mover is d, the number of phases of the applied power is P,
The piezoelectric linear motor according to claim 1, wherein the spacing between the piezoelectric actuators is (p+m/n)d/p, where m and n are positive integers. 3. 3. The piezoelectric linear motor according to claim 1, wherein the piezoelectric actuator is a bimorph actuator. 4. 4. The piezoelectric linear motor according to claim 3, wherein either one of the magnetic poles of the stator and the magnetic poles of the rotor is a permanent magnet.