JP2607560B2 - Linear actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a minute drive linear actuator which serves as a drive source for a precision positioning precision stage used in semiconductor equipment and the like.

2. Description of the Related Art In recent years, linear actuators have a linear motion in which the motion is different from the rotary motion of a rotary actuator, so that the driving force can be directly taken out as a linear motion. It is becoming increasingly used. As the linear actuator, a linear motor, a linear pulse motor, a piezoelectric ceramic actuator, and the like have been put into practical use, and as the fine drive and precision positioning, a large number of laminated piezoelectric ceramic actuators have been particularly used.

Hereinafter, an example of the above-described laminated piezoelectric ceramic actuator, which is the conventional linear actuator, will be described with reference to FIGS. 8 and 9. FIG.

FIG. 8 is a configuration diagram showing a structure of a laminated piezoelectric ceramic actuator which is a conventional linear actuator. In FIG. 8, reference numeral 1 denotes a piezoelectric ceramic green sheet, and reference numeral 2 denotes a metal electrode material printed on the piezoelectric ceramic green sheet 1 and serves as an internal electrode. Reference numeral 3 denotes an external electrode electrically coupled to the internal electrode 2. Reference numeral 4 denotes an insulator that electrically insulates the internal electrode 2 from the external electrode 3. Reference numerals 5a and 5b denote power supply terminal wires drawn from each of the external electrodes 3, and are formed by laminating the piezoelectric ceramic green sheets 1. It is connected to a drive power source 7 for driving the laminated piezoelectric ceramic actuator 6 to expand and contract.

The operation of the laminated piezoelectric ceramic actuator 6, which is a conventional linear actuator configured as described above, will be described below.

When a voltage is applied from the drive power supply 7 to the external electrodes 3, a voltage is also applied to the internal electrodes 2 printed on the piezoelectric ceramic green sheet 1. At this time, an electric field in a certain direction is applied to each of the piezoelectric ceramic green sheets 1, and a strain in each of the piezoelectric ceramic green sheets 1 is generated by an electrostriction effect. The amount of distortion is proportional to the number of laminated piezoelectric ceramic green sheets 1 and can be linearly extracted as the amount of displacement of the laminated piezoelectric ceramic actuator 6. Also, the laminated piezoelectric ceramic actuator 6
When a voltage in a direction opposite to that described above is applied to the external electrodes 3 from the drive power supply 7 in a state where is stretched, the laminated piezoelectric ceramic actuator 6 is driven in a contracting direction.

FIG. 9 is a diagram showing, as an example, a displacement amount when 100 V is applied from the driving power supply 7 to the laminated piezoelectric ceramic actuator 6 (piezoelectric ceramic green sheet element cross-sectional area 25 mm ² , length 18 mm). The vertical axis shows the displacement,
Voltage is shown on the horizontal axis. In FIG. 9, an arrow direction c indicates a displacement amount when the applied voltage is gradually increased, and an arrow direction d indicates a displacement amount when the voltage is gradually decreased.

Problems to be Solved by the Invention However, the above configuration has a problem that the amount of expansion and contraction of the laminated piezoelectric ceramic actuator 6 is very small with respect to the applied voltage of the driving power supply 7. Therefore, in order to increase the amount of expansion and contraction, it is necessary to further increase the applied voltage or to stack more piezoelectric ceramic green sheets 1, which results in an increase in the size of the drive power supply 7 and the size of the actuator, thereby increasing the cost. Had the problem that

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a linear actuator in which linear small displacements are continuously added in a certain direction, and can be taken out as a larger displacement. Is what you do.

Means for Solving the Problems In order to solve the above problems, the linear actuator of the present invention comprises a rod-shaped yoke material having magnetic pole teeth, a multilayer wound coil attached to the magnetic pole teeth, and applying a current to the coil. A coil power supply, a piezoelectric ceramic attached to the bar-shaped yoke member, and a drive power source configured to drive the piezoelectric ceramic to expand and contract to slightly change the bar-shaped yoke member. Two or more rod-shaped yoke members, each of which is opposed to the magnetic pole teeth of the two or more rod-shaped yoke members.
In this example, a plurality of rod-shaped magnetic bodies are arranged.

According to the present invention, the micro-displacement due to the expansion and contraction of the piezoelectric ceramic is transmitted to a rod-shaped yoke member having magnetic pole teeth attached to the piezoelectric ceramic, and the multilayer wound coil attached to the magnetic pole teeth is transmitted from a coil power supply. By applying an electric current, the magnetic pole teeth are formed as electromagnets, and a bar-shaped magnetic body arranged so as to face the magnetic pole teeth is attracted to the magnetic pole teeth, which has become the electromagnet, by an electromagnetic force and restrained, thereby causing a small displacement of the piezoelectric ceramics. From the magnetic pole teeth of the bar-shaped yoke material to the bar-shaped magnetic body. Also, only when the piezoelectric ceramic is displaced in the direction in which it extends, the multilayer body is excited to form an electromagnet. Can move continuously. And, of the two telescopic drive units,
When one piezoelectric ceramic moves in the direction in which the multilayer wound coil is extended in a state where the coil is excited, and when the other piezoelectric ceramic moves in the direction in which the multilayer wound coil is contracted without being excited, the exciters are separated from each other. The piezoelectric ceramics are driven in the direction of extension by the driving force of the ceramics by the amount of displacement of each piezoelectric ceramic. By repeating this, the magnetic body can be continuously moved in the extending direction by the driving force of the different piezoelectric ceramics.

Also, only when the piezoelectric ceramic is displaced in the contracting direction, the magnetic coil is excited to form the magnetic teeth portion as an electromagnet, and when the piezoelectric ceramic is displaced in the extending direction, it is not excited, and the magnetic material moves in the contracting direction of the piezoelectric ceramic. It can move continuously for each minute displacement. At this time, when one of the two expansion / contraction drive units moves in a contracting direction in a state where the multilayer wound coil is excited, the other piezoelectric ceramic extends without the multilayer wound coil being excited. When moving in the direction, the magnetic material can be driven by the displacement of each piezoelectric ceramic in the direction of contraction by the driving force of the separate piezoelectric ceramics. Can be. Accordingly, a linear minute displacement can be continuously taken out in a certain direction. In addition, since the magnetic pole teeth of one expansion / contraction drive unit always become an electromagnet and hold the magnetic body in an attracted state, even if the linear actuator vibrates due to external vibration or the like, the position of the magnetic body shifts. Nothing is gone.

Embodiment Hereinafter, a linear actuator according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a linear actuator showing one embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a laminated piezoelectric ceramic actuator by a green sheet method, 12 denotes a driving power supply for driving the laminated piezoelectric ceramic actuator 11 to expand and contract, and 13 denotes a laminated piezoelectric ceramic actuator.
11 is a bar-shaped yoke material attached to one end of
Has 14 Reference numeral 15 denotes a multilayer wound coil attached to the magnetic pole teeth 14, and reference numeral 16 denotes a coil power supply for applying a current to the multilayer wound coil 15. The first telescopic driving unit 17 is constituted by the above members 11 to 16. Also, a second telescopic drive unit
Reference numeral 18 denotes a laminated piezoelectric ceramic actuator 19 by the green sheet method, a driving power supply 20 for driving the laminated piezoelectric ceramic actuator 19 to expand and contract, and a bar-shaped yoke having magnetic pole teeth 21, similarly to the first telescopic driving unit 17. It is composed of a material 22, a multilayer wound coil 23 attached to the magnetic pole teeth 21, and a coil power supply 24 for applying a current to the multilayer wound coil 23. 25 and 26 are fixed ends of the first and second laminated piezoelectric ceramic actuators 11 and 19, respectively. Reference numeral 27 denotes a bar-shaped magnetic body made of a ferrite material disposed so as to face the magnetic pole teeth 14 and 21 of the bar-shaped yoke members 13 and 22. Reference numerals 28 and 29 denote rollers attached to the magnetic body 27, which slide on the guide 30 when the magnetic body 27 moves. Further, when current is applied to the multilayer wound coils 15 or 23 and the magnetic pole teeth 14 or 21 are formed as electromagnets, the magnetic body 27
Or it is prevented from being adsorbed by 21.

The operation of the linear actuator configured as described above will be described with reference to FIGS. FIG. 2 shows the first step of the linear actuator operation, in which the laminated piezoelectric ceramic actuators 11, 19 are shown.
In the figure, both the driving power supplies 12 and 20 are in the OFF state, the displacement amount is 0, and they are at the origin position. A current is applied to the multilayer wound coil 15 of the first telescopic drive unit 17 from the coil power supply 16, and the N pole and the S pole are polarized on the magnetic pole teeth 14 to form an electromagnet.
A polarity opposite to the tip polarity of the magnetic pole teeth 14 is generated in a portion facing the magnetic pole teeth 14, and a force is generated such that the magnetic pole teeth 14 and the magnetic body 27 are attracted to each other by the magnetic force.

FIG. 3 shows a second step of the linear actuator operation. In the first step state of FIG. 2, the drive power supply 12 of the multilayer piezoelectric actuator 11 is turned on to apply a voltage, and the multilayer piezoelectric ceramic is applied. Actuator
11 is driven in the direction of arrow j, that is, in the extending direction. At this time, since the rod-shaped magnet 27 is attracted to the magnetic pole teeth 14 by the electromagnetic force generated on the magnetic pole teeth 14 due to the excitation of the multilayer wound coil 15, the displacement of the rod-shaped yoke material 13, that is, the laminated piezoelectric ceramics The actuator 11 moves in the direction of arrow j by the same amount as the displacement of the actuator 11.

FIG. 4 shows a third step of the linear actuator operation. In the second step state, after the movement of the magnetic body 27 in the j direction is completed, the multilayer wound coil 23 of the second telescopic drive unit 18 is completed.
A current is applied from the coil power supply 24 to the magnetic pole teeth 21 to form an electromagnet, and a portion of the magnetic body 27 facing the magnetic pole teeth 21 generates a polarity opposite to the tip polarity of the magnetic pole teeth 21, and Magnetic material 27
And attract each other. Further, at this time, a current that generates an alternating magnetic field that demagnetizes the magnet portion of the magnetic body 27 formed in the portion opposed to the magnetic pole teeth 14 from the coil power supply 16 to the multilayer wound coil 15 of the first telescopic drive unit 17. Is applied.

FIG. 5 shows the fourth step of the linear actuator operation. The voltage of the driving power supply 12 is gradually reduced to the laminated piezoelectric ceramic actuator 11 of the first telescopic drive unit 17 so that the original displacement amount of 0 is obtained. The position, that is, the origin, is contracted in the direction of arrow k. At this time, a voltage is applied to the laminated piezoelectric ceramic actuator 19 of the second telescopic drive unit 18 from the drive power supply 20,
Driving is performed in the extending direction j in the same manner as in the second step. Accordingly, the magnetic body 27 also moves in the j direction by the same amount as the displacement of the laminated piezoelectric ceramic actuator 19.

FIG. 6 shows the fifth step of the linear actuator operation. In the fourth step, after the movement of the magnetic body 27 is completed,
A coil power supply 16 is applied to the multilayer wound coil 15 of the first telescopic drive unit 17.
More current is applied, and the magnetic pole teeth 14 are formed as electromagnets.
A polarity opposite to the tip polarity of the magnetic pole teeth 14 is generated at a portion of the magnetic body 27 facing the magnetic pole 27 so that the magnetic pole teeth 14 and the magnetic body 27 attract each other. Further, at this time, the magnetic pole teeth are supplied from the coil power supply 24 to the multilayer wound coil 23 of the second telescopic drive unit 18.
A current that generates an alternating magnetic field that demagnetizes the magnet portion of the magnetic body 27 formed in the portion facing the portion 21 is applied. When this demagnetization is completed, the drive power supply 20 is driven to the laminated piezoelectric ceramics actuator 19 in the direction of contraction by gradually lowering the voltage, and contracts in the direction of arrow k to the position of the displacement amount 0, that is, the origin. Further, when the drive power supply 12 of the multilayer piezoelectric ceramic actuator 11 is turned on, the second step state shown in FIG. 3 is attained. If the above operation is repeated continuously, the magnetic body 27 of the multilayer piezoelectric ceramic actuator 11, 19 is extended. It will move continuously in the direction.

FIG. 7 shows a sequence for driving the linear actuator according to one embodiment of the present invention.

Conversely, in order to move the magnetic body 27 in the direction in which the laminated piezoelectric ceramic actuators 11, 19 contract, in a state where the laminated piezoelectric ceramic actuators 11, 19 are expanded,
When the multilayer wound coils 15 and 23 are energized, the magnetic pole teeth 14 and 21 are formed as electromagnets, and when the laminated piezoelectric ceramic actuators 11 and 19 are at the origin positions, an alternating magnetic field is applied to the multilayer wound coils 15 and 23. The current to be generated may be applied.

As described above, according to the present embodiment, the two telescopic drive units 1
By providing 7,18, the multilayer piezoelectric actuator 1
1, 19 small displacements in a certain direction can be continuously provided to the magnetic body 27 as linear displacements. Further, the driving can be performed faster than the method of driving with only one expansion / contraction driving unit. Since one of the magnetic pole teeth 14 and 21 always attracts the magnetic body 27 by the electromagnetic force, the position of the magnetic body 27 is not disturbed by external vibration or the like.

In the present embodiment, two expansion / contraction drive units 17 and 18 are provided, but more may be provided. In addition, the bar-shaped yoke material 13,2
Although the two magnetic pole teeth 14 and 21 are each one, a plurality of them may be provided. Further, although the magnetic body 27 is made of a ferrite material, another magnetic material may be used. Further, although the sliding portions are the rollers 28 and 29 and the guide 30, it is needless to say that other mechanisms may be used. Further, the piezoelectric ceramics are laminated by a green sheet method,
However, it may be a bimorph type.

Advantageous Effects of the Invention As described above, according to the present invention, two or more expansion / contraction drive units are provided, and one rod-shaped magnetic body is disposed so as to face the magnetic pole teeth of two or more rod-shaped yoke members. Can be continuously applied to the magnetic body in a fixed direction, and the magnetic body can be driven faster than when a single expansion / contraction drive unit is driven. Further, since one of the magnetic pole teeth always holds the magnetic body by the electromagnetic force, even if external vibration or the like occurs, the position of the magnetic body can be stably positioned without being disturbed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a linear actuator showing one embodiment of the present invention, FIGS. 2 to 6 are operation explanatory diagrams showing first to fifth steps of the operation of the linear actuator, and FIG. The figure shows a sequence diagram for driving the linear actuator.
FIG. 1 is a configuration diagram of a laminated piezoelectric ceramic actuator which is a conventional linear actuator, and FIG. 9 is a diagram for explaining a voltage and a displacement amount applied to the laminated piezoelectric ceramic actuator of FIG. 11,19 …… Laminated piezoelectric ceramic actuator, 12,20
…… Drive power supply, 13,22 …… Bar-shaped yoke material, 14,21 …… Magnetic pole teeth, 15,23 …… Multilayer wound coil, 16,24 …… Coil power supply,
17 first telescopic drive unit, 18 second telescopic drive unit, 27
...... Rod-shaped magnetic material.

Claims (1)

(57) [Claims] 1. A bar-shaped yoke material having magnetic pole teeth, a multilayer wound coil attached to the magnetic pole teeth, a coil power supply for applying a current to the coil, a piezoelectric ceramic mounted on the bar-shaped yoke material, and the piezoelectric ceramics And a driving power source configured to drive the bar-shaped yoke material to slightly change the bar-shaped yoke material, and provided at least two telescopic driving portions, facing the magnetic pole teeth of the two or more bar-shaped yoke materials. Linear actuator in which one bar-shaped magnetic body is arranged.