JPH0449351B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a piezoelectric actuator that uses piezoelectric elements, and in particular, to a piezoelectric actuator that utilizes piezoelectric elements, and in particular to a piezoelectric actuator that utilizes piezoelectric elements, and in particular, a piezoelectric actuator that can be produced by skillfully combining a plurality of piezoelectric elements on a cantilevered rod-shaped body. The present invention relates to a piezoelectric actuator configured to increase the swing displacement at the free end portion of a rod-shaped body.

[Conventional technology]

Piezoelectric elements include, for example, single-crystal quartz, ceramics with a perovskite structure such as barium titanate, lead zirconate titanate, and lead titanate.
Furthermore, it is made of a piezoelectric material such as polyvinylidene fluoride, an organic material, and can function as a sensor by generating voltage when force is applied to it. Conversely, when voltage is applied, it generates a force. generated and can function as an actuator.

In recent years, piezoelectric actuators that perform various operations by skillfully combining piezoelectric elements with such characteristics have been actively developed.For example, there are laminated and bimorph types. generally known.

[Problem to be solved by the invention]

By the way, there are problems when using the piezoelectric element described above as an actuator.
The purpose is to adopt a configuration that can appropriately obtain displacement and generated force (thrust) according to the application.

However, the general laminated type and bimorph type described above have advantages and disadvantages, and in particular, one that has large displacement and generated force as described above has not yet been proposed, and can satisfy such requirements. There is a demand for the emergence of piezoelectric actuators. In other words, the former laminated type generates a large force but the displacement is small, while the latter bimorph type generates a large displacement but the generated force is small. be.

With these conventional actuator structures, it is necessary to increase both the displacement and the generated force, for example, when using it as a drive device such as a valve device, it is necessary to add some kind of amplification mechanism. Not only is it not possible to achieve the performance achieved by using such a piezoelectric actuator, but both of the above-mentioned piezoelectric actuators do not require lamination of multiple piezoelectric elements,
Since it is simply a product of two piezoelectric elements pasted together, it has drawbacks such as a lack of strength and rigidity, and it is desired that some kind of countermeasure be taken to eliminate these problems.

[Means to solve the problem]

In order to meet such demands, the piezoelectric actuator according to the present invention includes a rod-shaped body whose one end is fixed in a cantilever shape and whose free end portion on the other end can be oscillated, and a piezoelectric actuator that A piezoelectric element is provided in each of the plurality of notches. are fitted in such a way that the gaps between the corresponding notches are widened and narrowed.

Further, according to the present invention, comb-like notches each having an inverted chevron shape are formed along the longitudinal direction on one side of the cantilever-like rod-like body, and the size of the comb-like notches in the depth direction is A piezoelectric element is fitted in the part.

[Effect]

According to the present invention, a voltage is applied to the piezoelectric elements, and the piezoelectric elements are expanded and contracted so as to expand and narrow the gap between the comb-shaped notches in the cantilever-shaped rod-shaped body in which each piezoelectric element is fitted. , it is possible to increase the oscillating displacement output at the free end portion of the rod-shaped body and the generated force.

In particular, if the above-mentioned comb-like notches are formed into an inverted chevron shape and a piezoelectric element is fitted therein, the swing displacement output and generated force at the free end portion of the rod-like body can be further increased. .

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 shows an embodiment of the piezoelectric actuator according to the present invention, and in the figure, the piezoelectric actuator, which is designated as a whole by reference numeral 1, has one side surface that is comb-shaped along the longitudinal direction. The rod-shaped body 2 is provided with a cantilever-shaped metal rod-shaped body 2 formed with a notch as shown in FIG. The free end portion 2a on the end side is configured to be oscillated by a desired amount of displacement and generated force to become an output extraction portion.

Further, a voltage is applied intermittently to each of the plurality of comb-shaped notches 4 formed in parallel along the longitudinal direction on one side of the cantilever-shaped rod-shaped body 2. Accordingly, a piezoelectric element 5 which performs an expanding and contracting operation is fitted and is fixedly bonded within each of these notches 4 and is integrally connected to this rod-shaped body 2. These plurality of piezoelectric elements 5 act to widen and narrow the gap between the notches 4 of the rod-shaped body 2 into which they are fitted.

Each of these piezoelectric elements 5 is fitted in the notch 4 of the cantilever-like rod-shaped body 2 so as to leave the inner end portion as a space, thereby widening and narrowing the gap described above. This makes it possible to perform the functions smoothly and appropriately. In addition, in this embodiment, a comb-shaped notch 4 is formed along the longitudinal direction on one side of the cantilever-shaped rod-shaped body 2.
2 shows a case in which each of the holes is formed in the shape of parallel slits, and the inner end portion thereof forms a substantially circular hole.

Piezoelectric actuator 1 with such a configuration
According to the above, although the structure is simple and inexpensive, it is possible to increase the oscillating displacement output δ at the free end portion 2a of the cantilever-like rod-shaped body 2 as an output, and to reduce the generated force. It can also be made larger, and can be used as various actuators in various fields to exhibit its effects.

In other words, the piezoelectric element 5 can output an output as strain by applying an applied voltage as an input, but the amount of strain is about 10 ^-3 (μm), and this can be applied to various drives. In order to use it as a device, this amount of deformation must be considerably amplified. On the other hand, when the structure of this embodiment is adopted, although the amount of strain in the piezoelectric element 5 alone is small, the amount of displacement of the free end portion 2a as the cantilever-like rod-shaped body 2 can be increased. The rod-shaped body 2 can be displaced with a stroke of about 25 to 100 mm, although this varies depending on the cross-sectional shape of the rod-shaped body 2 depending on its width W and its length l. In the case of the above-described structure, when the piezoelectric element 5 is displaced in the direction of widening the gap due to the applied voltage,
In the cantilever-shaped rod-shaped body 2, the upper side on the element 5 side is deformed, but the lower side thereof is not deformed, so the curvature of the rod-shaped body 2 changes and becomes arc-shaped as shown by the dashed line in the figure. It is curved and deformed, and if one end is fixed, a considerable amount of displacement will occur at the free end portion 2a.

In addition, since the piezoelectric element 5 is used, the displacement amount and force generated in this manner can be directly obtained as a displacement output by the applied voltage, resulting in good operating efficiency. Furthermore, the overall spring stiffness is determined by the shape of the rod-shaped body 2, and the rigidity against displacement is determined by the rigidity of the above-mentioned cantilever-shaped rod-shaped body 2 itself, and cannot be set to a constant value. This can increase reliability in terms of overall strength. Further, according to the above-described configuration, the displacement and the repulsing force can be freely varied by controlling the voltage applied to each piezoelectric element 5 and applying the voltage to only an arbitrary element 5. There are also advantages such as
The piezoelectric actuator 1 having such a structure has the advantage that it has superior performance compared to conventional mechanical actuators because it does not include any members that cause friction or bumps.

FIG. 2 shows another embodiment of the piezoelectric actuator according to the present invention, and in this embodiment,
The comb-tooth-shaped notches 10 are formed along the longitudinal direction on one side of the cantilever-shaped rod-shaped body 2 so as to have an inverted chevron shape, and the inner end portions are left. This shows a case where a substantially wedge-shaped piezoelectric element 11 is fitted into most of the notch 10 in the depth direction.

According to such a configuration, the piezoelectric element 1
Since 1 has a wedge shape, the amount of displacement thereof is proportional to its thickness in the depth direction. Therefore, in such a configuration, since the displacement in the thick part of the piezoelectric element 11 is larger than in the thin part, each piece a, b can be easily moved over the entire length of each notch part 10. The center of rotation O can be obtained. As a result, the width W of the rod-shaped body 2 can be increased compared to the embodiment shown in FIG. 1, which has the advantage that the mechanical strength of the rod-shaped body 2 can be further increased. Here, in the figure, 11a is an insulating layer formed on the outside of the piezoelectric element 11, and 11b and 11c are a pair of electrode layers formed on the inside thereof.

Note that the present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part may be modified and changed as appropriate. For example, in each of the embodiments described above, the displacement can be changed by changing the amount of current applied to each piezoelectric element 5, 11, or by connecting each piezoelectric element 5, 11 in parallel and controlling the appropriate combination using a switch control. The amount and generated force can be freely varied. Furthermore, various modifications can be made to the shape, structure, etc. of the piezoelectric elements 5 and 11 described above.In short, the rod-shaped body 2 has a cantilever shape in which the free end portion 2a can be oscillated. Any material may be used as long as it can widen or narrow the gap by being fitted into the comb-like notches 4, 10 formed along the longitudinal direction on one side surface of the comb.

〔Effect of the invention〕

As explained above, the piezoelectric actuator according to the present invention includes a rod-shaped body whose free end portion is in the shape of a cantilever that can be oscillated, and a plurality of piezoelectric elements that perform expansion and contraction operations by applying a voltage. has
Notches are formed in one side of the rod-shaped body along the longitudinal direction so as to have a comb-like shape, and a piezoelectric material is applied to each of the plurality of notches in a state that can widen or narrow the gap between the corresponding notches. Since the elements are fitted, it is possible to increase the amount of rocking displacement at the free end portion of the cantilever-like rod-shaped body as an output, despite the simple and inexpensive configuration.
It is also possible to increase the generated force, so that it can be used effectively as various actuators in various fields. In particular, such an effect can be further enhanced by forming the above-mentioned comb-like notches so as to have a substantially inverted chevron shape, and by fitting piezoelectric elements into each of the notches.

Furthermore, according to the present invention, the reliability of the overall strength can be increased by the rigidity of the above-mentioned cantilever-shaped rod itself, and further, by appropriately controlling the voltage applied to the above-mentioned piezoelectric element, It has various excellent effects such as being able to freely vary its displacement and generated force.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing one embodiment of a piezoelectric actuator according to the present invention, and FIG. 2 is a partially omitted enlarged side view of a main part showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Piezoelectric actuator, 2...Cantilever-shaped rod-shaped body, 2a...Free end portion, 3...Fixed part, 4, 10...Comb tooth-shaped notch part, 5, 11...
Piezoelectric element.

Claims (1)

[Claims] 1. A rod-shaped body 2 configured such that one end is fixed in a cantilever shape so that the free end portion 2a on the other end side can be oscillated, and a rod-shaped body 2 that can be expanded and contracted by applying a voltage. A piezoelectric actuator 1 is made up of a plurality of piezoelectric elements 5 and 11, in which one side of the rod-shaped body 2 is cut out so as to have a comb-like shape along its longitudinal direction. The piezoelectric element 5,
11 is fitted in such a manner that the gap between the corresponding notches 4 and 10 is widened and narrowed. 2 The comb-like notches 10 formed along the longitudinal direction on one side of the cantilever-like rod-like body 2 are each cut out so as to have an inverted chevron shape, and the size in the depth direction is 2. A piezoelectric actuator according to claim 1, wherein a piezoelectric element 11 is fitted in a portion thereof.