JP2514598Y2 - Piezoelectric element displacement magnifying mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a piezoelectric element displacement magnifying mechanism for magnifying the displacement of a piezoelectric element as a drive source, and particularly to the structure thereof.

[Conventional technology]

Conventional piezoelectric element displacement magnifying mechanism (hereinafter referred to as magnifying mechanism)
This will be described with reference to FIGS. 3 (a) and 3 (b).

FIG. 3A is a diagram showing an example of a magnifying mechanism that mechanically magnifies the displacement generated by a laminated piezoelectric ceramic element (hereinafter referred to as a piezoelectric element) 1.

This enlargement mechanism connects two lever arms 3 for transmitting the displacement generated by the piezoelectric element 1 in the direction of ∘ in the drawing through the first hinge 2 to enlarge the lever arm 3 and the mounting substrate 4. The second hinge 5 and the beam 6 as a displacement magnifying means fastened in a bridge shape to the tip of the lever arm 3 by a rivet.

The first hinge 2, the second hinge 5, the mounting substrate 4, and the lever arm 3 have an integrated structure, and this integrated structure will be referred to as a displacement magnifying metal member 7 hereinafter.

The displacement magnifying metal 7 is manufactured by processing a metal plate by wire cutting or electric discharge machining.

FIG. 3 (b) is a perspective view showing the structure of the beam 6 used in the conventional enlarging mechanism shown in FIG. 3 (a).

The beam 6 is a trapezoidal shape in which a thin metal plate is punched by a press punching method, the movable portion 8 is bent so that it is easily buckled and deformed, and the central portion of the beam 6 has sides parallel to both ends of the beam 6. It is made by molding.

At both ends of the beam 6, fastening portions 9 formed in a U-shape according to the plate thickness of the lever arm 3 are provided, and a circular rivet hole 10 is provided at the center of each fastening portion.

Here, in FIG. 3A, from the central portion of the beam 6,
The distance from the central portion of the side surface of the mounting substrate 4 facing the beam side is referred to as the beam height.

Next, a method of assembling the enlarging mechanism having the above-described configuration will be described.

First, both ends of the piezoelectric element 1 are bonded to the first hinge 2 with an adhesive made of a thermosetting resin.

Next, the beam 6 and the rivet 11 are prepared, the U-shaped fastening portion 9 of the beam 6 is combined with the tip of the lever arm 3, and the rivet hole 12 provided at the tip of the lever arm 3 and the beam 6 The rivet 11 is overlapped with the rivet hole 10 and the rivet 11 is penetrated, and the rivet 11 is molded into a predetermined size by a hydraulic press machine or the like to complete the assembly of the expansion mechanism.

Next, the operation of the enlarging mechanism thus assembled will be described.

When a voltage is applied to the piezoelectric element 1, the piezoelectric effect causes a displacement in the piezoelectric element 1 in a direction indicated by a mark ↔ in FIG. 3A, and this displacement is caused via the first hinge 2 to the lever arm. It is transmitted to 3.

The lever arm 3 uses the transmitted displacement by the lever principle with the second hinge 5 as a fulcrum.
Enlarge at the tip of.

This enlarged displacement is transmitted to both ends of the beam 6 fastened in a bridge shape to the tip of the lever arm 3 as displacement in the longitudinal direction of the beam 6.

The beam 6 receives the displacement in the longitudinal direction and, according to the well-known buckling theory, generates the maximum displacement in the direction indicated by the mark at the central portion.

After that, when the applied voltage is set to 0 volt, the displacement of the piezoelectric element 1 is restored and the displacement of the beam 6 is also restored at the same time.

[Problems to be solved by the device]

In the conventional expansion mechanism described above, the rivet holes 10 provided in the fastening portions 9 at both ends of the beam 6 are circular with the same diameter as the rivet 11.

Here, when the rivet hole 10 of the beam fastening portion 9 and the rivet hole 12 at the tip of the lever arm 3 are overlapped and the rivet 11 is inserted and a force is applied in the axial direction of the rivet 11 by a hydraulic press machine or the like, compression molding is performed. A concentrated load is applied to the edge of the rivet hole 10 of the fastening portion 9 sandwiched between the head of the rivet 11 and the lever arm 3.

When this concentrated load becomes large, a tensile stress is generated in the fastening portion 9 in the radial direction from the center of the rivet hole 10 and a compressive pressure is generated in the circumferential direction.

However, since the fastening portion 9 is thin and has low shape rigidity, the above-described stress causes the fastening portion 9 to bend, and the bending causes the shape of the entire beam 6 to change.

This is because the shape rigidity of the beam 6 changes.
This corresponds to a change in the spring constant of the beam 6 as a buckling spring.

Specifically, the beam height varies as shown in FIG. 3 (a), and as a result, the maximum displacement of the beam 6 at the central portion greatly varies.

As described above, the conventional enlarging mechanism has a drawback that the maximum displacement in the central portion of the beam is large.

[Means for solving the problem]

The piezoelectric element displacement magnifying mechanism according to the present invention is a piezoelectric element displacement magnifying mechanism including two lever arms for transmitting and magnifying the displacement of a piezoelectric element, and a beam fastened in a bridge shape between the tips of the lever arms. The beam is characterized in that it has notches radially arranged from the center of the rivet hole around the rivet hole provided at the fastening portions at both ends of the beam.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing the structure of a beam in the first embodiment of the present invention.

In the beam 6 of the conventional enlarging mechanism shown in FIG. 3 (b), the beam 13 in this embodiment has only a circular rivet hole 10 in the center of the fastening portion 9, whereas the beam 13 is fastened. Part 14
Around the central circular rivet hole 10, four notches 15 are radially provided.

The assembling method in the case of assembling the beam 13 having the above-described structure to manufacture the enlarging mechanism is the same as the assembling method of the conventional enlarging mechanism described above.

Here, when using the beam 13 having the above-described structure to assemble the enlargement mechanism by the same assembling method as in the related art, when fastening the lever arm and the beam 13 with the rivets, as in the conventional enlargement mechanism. , The rivet hole in the fastening portion 14 of the beam 13
Tensile stress in the radial direction centered on 10 and compressive stress in the circumferential direction are generated, which may cause flexure in the fastening portion 14, but this flexure is a cut 15 formed radially around the rivet hole 10. Is alleviated by

 Therefore, the overall shape of the beam 13 does not change.

Next, in order to confirm the above, the results of measuring the beam height variation and the maximum displacement variation of the enlargement mechanism according to the present embodiment will be described.

First, 42 mm of 42Ni-Fe material with a longitudinal elastic modulus of 14.8 × 10 ³ kg / mm ² is 4 mm.
35mm x 30 in outer diameter with wire cut electrical discharge machining
50 mm displacement magnifying brackets were manufactured.

To this, a piezoelectric element in which a conventionally known lead zirconate titanate-based ceramics was laminated was adhered with a thermosetting resin (Amicon A-401).

Next, after the adhesive was hardened, the piezoelectric element attached to the displacement enlarging metal fitting was subjected to polarization treatment under the same polarization conditions as the conventional one.

A beam having a diameter of 2.7 mm and a rivet hole which was cut in the radial direction at four places with a diameter of 2.7 mm was cut in the periphery with aluminum rivets.

The variation in beam height of the magnifying mechanism thus obtained was 0.02-0.09 mm for the designed value of 6.05 mm.

The maximum displacement at the center of the beam when DC150V was applied to this expansion mechanism was 0 to -0.12% with respect to the design value of 0.34 mm.

On the other hand, it has a conventional diameter of 2.
A beam having a rivet hole of 7 mm was manufactured in the same way by the same assembling method as in the example of 50 pieces, and the variation in beam height was 0.05 to 0.17 mm, and the variation in maximum displacement was −5.0 to
It was -25%.

That is, in this embodiment, by making radial cuts around the rivet hole provided in the fastening portion of the beam,
The variation in maximum displacement could be reduced to less than half.

Next, in order to confirm the effect of the present invention in the case where the spring constant of the beam becomes small and the effect of deflection due to rivet fastening becomes easy, the expansion mechanism having a beam whose beam height is smaller than that described above is used. Was manufactured, and the variation of the beam height and the variation of the maximum displacement were investigated.

The design values of beam height and maximum displacement are as follows.

Beam height = 5.8mm Maximum displacement = 0.285mm The number of manufacturing is 50 for each of the expansion mechanism according to the present invention and the conventional expansion mechanism.

In this case, the variation in beam height and the variation in maximum displacement were as follows.

 In the case of the enlargement mechanism according to this embodiment.

Variation in beam height = 0.02 to 0.08 mm Variation in maximum displacement = 0 to -13% For conventional expansion mechanism.

Variation in beam height = 0.02 to 0.18 mm Variation in maximum displacement = -4 to -25% As can be seen from the above results, the beam whose spring constant became smaller due to the reduced beam height was riveted. Even in this case, the variation of the maximum displacement could be reduced to half that of the conventional one.

 Next, a second embodiment of the present invention will be described.

FIG. 2 (a) is a perspective view showing a second embodiment of the present invention, and FIG. 2 (b) is an enlarged sectional view showing an AA cross section of FIG. 2 (a).

In this embodiment, the displacement enlarging metal fitting 16 has a laminated structure, which is different from those of the conventional and first embodiments.

The displacement magnifying bracket 16 is manufactured by stamping a thin metal plate (thickness 0.15 to 0.4 mm) made of a highly rigid metal material.
At this time, the mounting board 4 and the lever arm 3,
A part of an arbitrary shape is punched out or the entire circumference is punched out to form a square-shaped crimped portion 17, and the crimped portions 17 are stacked one on top of another and sandwiched by the frictional force of the cut surface of the protrusion of the crimped portion 17 .

At the tip of the lever arm 3 of the enlargement mechanism according to this embodiment, a beam 13 identical to that of the first embodiment shown in FIG.
It is fastened with rivets.

The rivet fastening method and operation in this embodiment are the same as those in the first embodiment and the conventional expansion mechanism.

In the enlarging mechanism according to this embodiment, the longitudinal elastic modulus is 14.8.
When pressing 0.43 mm thick 42Ni-Fe material of × 10 ³ kg / mm ² , the mounting substrate 4 and the lever arm 3 are each provided with a caulking part that is half-punched on the entire circumference of the square type. Form 3 and 2 places, stack 10 sheets and stack thickness 4mm, outer diameter 35mm x 3
50 pieces of 0mm displacement magnifying bracket were produced.

Next, the displacement magnifying member is attached to the beam in the first embodiment.
A beam with the same shape and structure as 13 was fastened with aluminum rivets.

The variation in beam height in the expansion mechanism of this laminated structure was 0.02 to 0.1 mm with respect to the design value of 6.05 mm. or,
The maximum displacement variation is 0-- with respect to the design value of 0.34 mm.
It was 13%.

From the above results, it was confirmed that the same effects as those of the first embodiment can be obtained also in the present embodiment. [Advantages of the Invention] As described above, the present invention has the rivet provided at the fastening portion of the beam. When the beam and the lever arm are fastened with rivets, by making radial cuts around the hole,
It is possible to reduce the bending that occurs in the fastening portion of the beam.

Therefore, since it is possible to prevent the shape of the entire beam from changing, it is possible to suppress variations in beam height to a minimum, and to reduce variations in maximum displacement to half that in the conventional case.

[Brief description of drawings]

FIG. 1 is a perspective view showing the structure of a beam in the first embodiment of the present invention, FIG. 2 (a) is a perspective view showing the structure of the second embodiment of the present invention, and FIG. 2 (b). ) Is a cross-sectional view showing the structure of the AA cross section in FIG. 2 (a), FIG. 3 (a) is a perspective view showing the structure of a conventional expansion mechanism, and 3 (b) is a conventional expansion. It is a perspective view which shows the structure of the beam in a mechanism. 1 ... Piezoelectric element, 2 ... First hinge, 3 ... Lever arm, 4 ... Mounting board, 5 ... Second hinge, 6,13 ... Beam,
7,16 …… Displacement expansion metal fittings, 8 …… Movable part, 9,14 …… Fastening part, 10,12 …… Rivet hole, 11 …… Rivet, 15 …… Notch, 17 …… Crimping part.

Claims (1)

(57) [Scope of utility model registration request] 1. A piezoelectric element displacement enlarging mechanism comprising two lever arms for transmitting and enlarging a displacement of a piezoelectric element, and a beam fastened in a bridge shape between respective tip ends of the lever arms. A piezoelectric element displacement enlarging mechanism characterized in that it has notches radially arranged from the center of the rivet hole around the rivet hole provided in the fastening portions at both ends.