JPH0199672A - Method for control of electric distortion drive means - Google Patents

Abstract

PURPOSE: To make it possible to achieve large displacement without the occurrence of polarization destruction of electrostrictive elements constituting electrostrictive laminates by arranging the electrostrictive laminates above and below a working section and subjecting the electrostrictive laminates to a prescribed voltage control and a position control. CONSTITUTION: A pair of the electrostrictive laminates 2a to 2d constituted by laminating the polarized electrostrictive elements 10 are disposed above and below the working section 5a and the driving end 3 thereof is arranged to face the working section 5a. Further, the alternating voltages at which the absolute values of positive voltage exceed the absolute value of negative voltage are impressed to the upper and lower electrostrictive laminates in such a manner that the phases are reversed from each other. In addition, the voltage impression to allow the driving ends 3 to form clearances with each other in a voltage releasing stage and to fill the clearances by the expansion to each other at the time of non-operation is executed. Consequently, the large displacement may be achieved without the occurrence of the polarization destruction of the electrostrictive elements 10 constituting the electrostrictive laminates and without the occurrence of hindrance in holding of the working section 5a. The drive assembly useful as a displacement generation source is thus obtd.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electrostrictive drive device applied to a mechanism that requires displacement, such as a cyclic fatigue testing device for inspecting bending fatigue of ceramic samples. Regarding control method.

<Problems to be Solved by the Invention> As an electrostrictive drive device, a pair of electrostrictive laminates are arranged above and below an actuating part, and the driving ends of the electrostrictive laminates are placed opposite to the actuating part, and one of the electrostrictive laminates is It may be proposed that the actuating portion is caused to extend and contract according to the drive timing in which the actuating portion is raised and the other portion is extended, thereby imparting reciprocating vertical displacement to the operating portion.

An object of the present invention is to provide a control method with such a configuration that can increase the displacement as much as possible.

Means for Solving the Problems> The present invention provides a pair of electrostrictive laminates formed by stacking polarized electrostrictive elements above and below an actuating part, and the driving end thereof is placed opposite to the actuating part. At the same time, an alternating voltage in which the absolute value of the positive voltage exceeds the absolute value of the negative voltage is applied to the upper and lower electrostrictive laminates so that the phases are opposite to each other, and when the voltage is released,
A gap is formed between the drive ends, and when not driven,
mutually extending said r1! This device is characterized in that a voltage is applied to fill the IPI1.

Effect> The amount of expansion and contraction of the carcasses of the pair of electrostrictive jA layers arranged above and below the actuating part is proportional to the applied voltage, but since the negative voltage is opposite to the polarization direction of the electrostrictive element, the negative voltage If the absolute value of is large, polarization destruction occurs. Therefore, the absolute value of the negative voltage is set to be less than or equal to the polarization voltage, and the absolute value of the positive voltage is set to be greater than or equal to the absolute value of the negative voltage.

As a result, the amount of expansion of the electrostrictive laminate is greater than the amount of contraction, based on the state in which no voltage is applied.

By the way, if the driving ends of the upper and lower electrostrictive carcasses are placed in contact with the actuating part in the non-applied state, then as the alternating voltage is applied, the driving ends of the electrostrictive laminate on the extension side will become actuated. The working end of the electrostrictive carcass on the other contracting side is strongly pressed with a pressure corresponding to the excessive extension through the part, mutual internal stress is generated, and the element is destroyed. Therefore, a gap is created between the drive ends by the amount of the excess gap in a non-applied state.

As a result, mutual expansion and contraction is performed without generating internal stress, resulting in reciprocating displacement of the operating portion.

In addition, in the non-applied state, the actuating part cannot be held between the driving ends of the electrostrictive laminate due to the gap, so in the non-actuating state, the amount of extension that can fill the gap between the electrostrictive laminates is limited. A positive voltage is applied to each other to cause the two to occur.

Therefore, when a voltage is applied at a driving timing when the expansion and contraction phases of the electrostrictive laminates that are adjacent to each other on the upper and lower sides are reversed, the actuating part is given a reciprocating vertical displacement, and therefore, if a driven body is connected to the actuating part, , it is possible to cause the driven body to undergo a large reciprocating displacement.

<Embodiment> Fig. 1.2 shows the present invention applied to a displacement magnification mechanism using the principle of leverage.

Here, on the upper and lower holding surfaces 1.1, a pair of electrostrictive laminates 2a and 2b and an electrostrictive laminate 2c and 2d are provided oppositely on the upper and lower sides.
is held with its drive end 3 facing inward.

An operating portion 5a of an operating rod 5 is interposed between each driving end 3 of the electrostrictive laminates 2a, 2b and the electrostrictive laminates 2c, 2d,
The electrostrictive laminate 2a, 2% (2b, 2d) 1l
At fl, the support shaft 6 protrudes from both sides and is pivotally supported. Further, on both sides and the front and back of the support shaft 6, electrostrictive v1 layer bodies 2a, 2b are provided.
, 2c, 2d (7) A contact method 7 is embedded at a position facing each drive end 3. Furthermore, the other end of the operating rod 5 is an output end 5b connected to a driven body.

The electrostrictive laminates 2a, 2b and the electrostrictive laminates 2c, 2d are made of a piezoelectric composite material or a piezoTIt ceramic material, and electrically conduct the four electrostrictive elements 1O in the figure, which are polarized in the thickness direction, in the width direction. They are stacked in parallel and a wear-resistant material is fixed to the end perpendicular to the stacking direction to form the drive end 3. In the bending configuration, when an alternating voltage is applied to each electrostrictive element 10, this strain is superimposed and it expands and contracts in the thickness direction, but this expansion and contraction occurs due to the relationship of Poisson's ratio and the mode of the piezoelectric constant dffl. This causes the drive end 3 to expand and contract.

The electrostrictive laminates 2a, 2b and the electrostrictive laminate 2 having this configuration
Although the piezoelectric constant d 31 is small in c and 2d, a sufficiently large displacement can be achieved with a relatively low voltage and even with a small number of a layers. In addition, in the direction of the a-layer, each electrostrictive element 1O is bonded with an adhesive, so the tensile force in the lamination direction tends to cause peeling of the planting layer surface, and although it is weak against tensile force, as mentioned above, Since it uses a mode with a piezoelectric constant d31 that is perpendicular to the lamination direction, it is strong against tensile force.

Then, when the HA drive end contacts the contact method 7 and the electrostrictive laminates 2a and 2d expand, the electrostrictive laminates 2b and 2c
By applying a voltage timing at which the voltage is contracted by the voltage applying means 12, the operating rod 5 swings about the support shaft 6, and a large reciprocating displacement occurs at the output end of the operating rod 5.

An example of voltage control by this voltage applying means 12 is shown in Section 3.4.
The diagram will be explained.

Footwear bodies 2a, 2b and 2c, 2 are attached to the electrostrictive 11 facing upwardly and downwardly.
A voltage with an inverted phase is applied to d. At this time,
When a negative high voltage opposite to the polarization direction is applied to each electrostrictive element 10, the polarization disappears or is reversely polarized.
For example, 1000 V/mm (positive voltage) is applied, and 250 V/5l (7) is applied in the contraction direction (negative voltage). This voltage distribution shifts the zero reference of the AC voltage to the negative side, as shown in Figure 4. This is achieved by controlling the

Correspondingly, the electrostrictive laminates 2a, 2b, and 2c
, 2d has a total length of 20mm, the amount of contraction displacement is 2mm
Although the amount of extensional displacement is larger than the amount of contractional displacement, such as the amount of extensional displacement is 8 mm, the electrostrictive laminates 2a, 2b, and 2c are
2d, a distance of about 8 m (see Fig. 3A) is created with the voltage removed.

- On the other hand, in this voltage release state, the actuating part 5a cannot be held, so in the non-actuating state of one actuating rod 5, the electrostrictive laminates 2a, 2b and 2c, 2d are respectively equal to A positive voltage is applied to slightly expand the actuating portion 5a to fill the gap and hold the actuating portion 5a.

With this configuration, as shown in FIG. It performs a tilting motion about the support shaft, and is taken out as an enlarged displacement from the output end 5b. By linking a driven body to the output end 5b, this displacement can be used for various purposes such as a drive source for a pump, a drive source for a fatigue testing device, etc.

Instead of the electrostrictive laminates 2a and 2b and the electrostrictive laminates 2c and 2d, as shown in FIG. 5, a number of piezoelectric layers 21 polarized in the thickness direction are electrically arranged in parallel in the vertical direction to form an a-layer. A driving end 22 made of a wear-resistant material is provided at the end thereof, and this is brought into contact with the above-mentioned contact method 7, and the piezoelectric constant d 3
Electrostrictive laminates 20a, 20b, 20c, and 20d that apply force in the stacking direction to the contact method 7 in three modes may be applied.

When these electrostrictive laminates 20a, 20b, 20c, and 20d are used, the electrostrictive laminates 20a, 20b, and 20
c and 20d apply preload to each other via the operating rod 5, increasing the durability of the electrostrictive laminate.

In each of the above-mentioned embodiments, one end of the operating rod 5 is given a tilting motion about the support shaft 6, and the other end is caused to undergo a large displacement by the action of the lever. By using an electrostrictive laminated body, the displacement of the actuating part between its driving ends may be used directly as a source of displacement, or the driven body itself may be placed between a pair of electrostrictive laminated bodies. , this may be used as the actuating part.

<Effects of the Invention> As described above, the present invention has electrostrictive laminates arranged above and below the actuating section, and the electrostrictive laminates are subjected to predetermined voltage control and position control. It has excellent effects such as being able to achieve large displacements without causing polarization breakdown of the electrostrictive elements that make up the strained laminate and without causing problems in holding the operating parts, making it extremely useful as a displacement generation source. .

[Brief explanation of the drawing]

Figure 1 is a side view of the displacement magnification mechanism to which the present invention is applied;
The figure is an enlarged longitudinal sectional side view of one end of the operating rod 5. Further, FIG. 3 is an operation explanatory diagram showing expansion and contraction control of the electrostrictive element, and FIG. 4 is a voltage waveform diagram. Further, FIG. 5 is a side view of a displacement magnifying mechanism to which another electrostrictive laminate is applied. 2a, 2b, 2c, 2d; Electrostrictive a carcass 3; Drive end 5
; Operating rod 5a; Operating part 5b: Output end 6: Support shaft
10. Electrostrictive elements 20a, 20b, 20c, 20d; Electrostrictive laminate 21; Electrostrictive element 22; Drive end Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] 1) A pair of electrostrictive laminates formed by laminating polarized electrostrictive elements are disposed above and below the actuating part, and the driving ends thereof are placed opposite to the actuating part, and the upper and lower electric Applying an alternating voltage in which the absolute value of the positive voltage exceeds the absolute value of the negative voltage to the strained laminate so that the phases are opposite to each other, and in a voltage released state, a gap is formed between the drive ends. A method for controlling an electrostrictive drive device, further comprising applying a voltage that expands mutually and fills the gap when the device is not in operation. 2) The electrostrictive laminate has a piezoelectric constant d_3_ in which a plurality of electrostrictive layers are laminated and the end perpendicular to the lamination direction is the driving end.
2. The method of controlling an electrostrictive drive device according to claim 1, wherein the electrostrictive drive device is constructed of an electrostrictive laminate using one mode. 3) The electrostrictive laminate is constructed by laminating a plurality of electrostrictive layers and using a piezoelectric constant d_3_3 mode with an end in the stacking direction serving as a driving end. A method for controlling an electrostrictive drive device according to scope 1.