JPH041361Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Industrial Application Field The present invention relates to a displacement mechanism using a piezoelectric element.

B. Prior Art Displacement mechanisms that use piezoelectric elements to obtain minute displacements have been known, but when obtaining displacements of several tens of micrometers to several hundred micrometers, bimorph piezoelectric elements are used.

For example, FIG. 9 shows a nozzle flapper of a servo valve such as a current-pneumatic converter using a bimorph piezoelectric element. Here, 21 is a flapper made of a bimorph piezoelectric element, and 22 is a nozzle. The amount of deflection of this type of flapper 21 is controlled by a pulse width modulation method (hereinafter referred to as a PWM method), or the amount of deflection is controlled by a DC voltage.

C. Problems to be solved by the invention However, in the case of the PWM method, there is a problem in its durability because the bimorph piezoelectric element is repeatedly deformed. In addition, when controlling with DC voltage, a creep phenomenon of the piezoelectric element occurs, and even if the pressure obtained from the servo valve is controlled by applying feedback by nozzle back pressure, there is a risk that it will deviate from the control range of the electric circuit. For example, there is a possibility that the nozzle back pressure cannot be controlled to a predetermined value or higher. Furthermore,
In general, the bimorph type has problems in that although a relatively large displacement can be obtained, the generated force is small, the reproducibility of displacement is poor, and the strength is weak.

An object of the present invention is to solve such conventional problems and provide a displacement mechanism that uses a laminated piezoelectric element to obtain displacement equivalent to that of a bimorph piezoelectric element.

D. Means for Solving the Problems In order to achieve such an objective, the displacement mechanism of the present invention has a leaf spring supported in a cantilever manner on the main body, and a part of the leaf spring protruding from the main body has a part that is attached to the main body. An input section rising from the displacement section at a predetermined angle of inclination is connected to the free end of the input section, and by displacing the free end using the fixed end of the displacement section as a fulcrum, the entire displacement section can be moved. A laminated piezoelectric element that is deformed using its fixed end as a fulcrum is attached, and the piezoelectric element is arranged so that the direction of expansion and contraction of the laminated piezoelectric element substantially coincides with the rising direction of the input section.

E Effect When a control voltage is applied to the laminated voltage element and the piezoelectric element expands, the input section is displaced. This displacement is transmitted from the fixed end of the input section to the leaf spring, and the free end of the leaf spring is displaced by an amount expressed by (displacement of input section x magnification). The magnification rate is expressed by the ratio L/l of the distance l from the free end of the input section to the fixed end of the leaf spring to the distance L from the fixed end to the free end of the leaf spring.

F Embodiment FIGS. 1 to 8 show an example in which the displacement mechanism according to the present invention is applied to a nozzle flapper of a voltage-pneumatic converter, and FIG. 1 is a sectional view taken along the line - in FIG.
FIG. 2 is a plan view, and FIGS. 3 to 7 are views showing the constituent elements.

Reference numeral 1 indicates a leaf spring, and as shown in FIGS. 3a and 3b, the leaf spring 1 has a mounting part 1a with an opening 1b in the center, and a mounting part 1a that is connected to the mounting part 1a and is folded slightly upward in the figure. From a bent triangular displacement part 1c and a tongue-shaped input part 1d, which is made with a width narrower than the opening 1b at approximately the center of the displacement part 1c, and whose tip on the opening side is bent upward in the figure. Become.

2 is a main body, which includes a mounting part 2a having a U-shaped planar shape as shown in FIGS.
A columnar part 2b is connected to the end of the columnar part 2b, and a surface 2c of the columnar part 2b on the mounting part 2a side is an inclined surface as shown in FIG. 4b with respect to the mounting part 2a.

The leaf spring 1 is attached to the main body 2, but the leaf spring 1
The plate spring 1 is placed on the mounting part 2a by inserting the columnar part 2b into the opening 1b from below, and the pressing plate 3 is provided on the upper surface of the leaf spring mounting part 1a, and the lower surface of the mounting part 2a is placed on the lower surface of the mounting part 2a. A spring presser 5 having the shape shown in , b is provided, and a presser plate 3, a leaf spring 1, and a main body 2 are provided.
By tightening the retaining plate 6 together with the bolts 4, the leaf spring 1 is held between the retaining plate 3 and the mounting portion 2a, and the spring retaining plate 5 is held against the retaining plate 6.
and the mounting portion 2a. Here, the tip 5a of the spring retainer 5 is in contact with the lower surface of the plate spring 1 at the substantially center thereof, and supports the plate spring 1.

Reference numeral 7 designates a laminated piezoelectric element, and as shown in FIGS. 6a and 6b, a holding plate 8 having a V-shaped groove 8a carved on one end surface is attached by adhesive or the like. The input portion 1d of the leaf spring 1 is locked in the groove 8a of the holding plate 8. The other surface of the piezoelectric element 7 is attached to the inclined surface 2c of the main body 1 via a holding plate 11. Here, if the inclination angle θ ₁ of the input part 1d and the inclination angle θ ₂ of the inclined surface 2c are set equal, the direction of the load input from the piezoelectric element 7 to the input part 1d will be parallel to the plane of the input part 1d. , the leaf spring 1 can be deformed by efficiently using the stress generated by the piezoelectric element 7.

Furthermore, in FIGS. 1 and 2, reference numeral 9 denotes a support plate, and as shown in FIGS. 9a is carved, and one end side has a screw 9.
b is screwed. This support plate 9 is inserted into the opening 1b of the leaf spring 1, the groove 9a is locked to the periphery of the opening 1b on the opposite side from the input part 1d, and the other end 9c is welded to the columnar part 2b. There is. Then, the screw 10 is screwed onto the screw 9b, and the screw 10 is screwed onto the screw 9b.
The tip of the piezoelectric element 7 is pressed into contact with the columnar part 2b, whereby the support plate 9 is bent about the end part 9c as a fulcrum, and the main body 2 and the piezoelectric element 7 are tightened by the leaf spring 1.

The operation of the displacement mechanism configured in this way will be explained.

When a voltage having the waveform shown in FIG. 8 is applied to the piezoelectric element 7, the piezoelectric element 7 expands at time _T1 , and the input section 1
Press d. That is, as shown in Fig. 3b, a load P is input to the input part 1d, and as a result, the displacement part 1c moves in the q direction (Fig. 3b ) is displaced.

At this time, as shown in Fig. 3b, the length from the fixed fulcrum part Y to the free end of the displacement part 1c is L, the distance from the fixed fulcrum part Y to the free end Z of the input part 1d is l, and the input load If the displacement of the input part 1d due to P is δ, then the displacement in the q direction at the free end of the displacement part 1c is Q
can be expressed as Q=δ×L/l. That is, the displacement of the input section 1d by the piezoelectric element 7 is expanded to L/l.

In this way, in the nozzle flapper, the displacement part 1
When c is displaced, the nozzle back pressure changes, thereby controlling the duty ratio of the input waveform to the piezoelectric element 7, thereby controlling the nozzle back pressure.

In the above, the case where the displacement mechanism according to the present invention is applied to the nozzle flapper of a voltage-pneumatic converter has been explained, but various devices other than the nozzle flapper,
In other words, the present invention can be applied to various types of displacement mechanisms that obtain minute displacements of several tens of micrometers to several hundred micrometers.
Further, the shapes of the leaf spring 1, the main body 2, etc. are not limited to the above embodiments.

G. Effects of the invention Since the invention is constructed as described above, it has a simple construction using a laminated piezoelectric element with a relatively small amount of displacement, and has the same size as a bimorph piezoelectric element, ranging from several tens of micrometers to several micrometers.
A relatively large displacement of 100 μm can be obtained, and all the problems of the conventional displacement mechanism using bimorph piezoelectric elements can be solved.

[Brief explanation of the drawing]

1 to 8 show an embodiment of the present invention, in which FIG. 1 is a cross-sectional view taken along the - line in FIG. 2, FIG. 2 is a plan view, and FIGS. 3 a and 3 are plan views and Side view, Figures 4a, b, and c are a plan view, side view, and perspective view of the main body; Figures 5a, b are a plan view and side view of the spring retainer; Figures 6a, b are the front of the retainer plate. Figures 7a and 7b are front and side views of the support plate, Figure 8 is a diagram showing an example of the input waveform to the piezoelectric element, and Figure 9 is a diagram showing an example of the input waveform to the piezoelectric element. It is a figure showing an example of a nozzle flapper. DESCRIPTION OF SYMBOLS 1... Leaf spring, 1c... Displacement part, 1d... Input part, 2... Main body, 2a... Mounting part, 2b... Column part, 5... Spring retainer, 6... Stop plate, 7... Laminated piezoelectric element, 8, 11...pressing plate, 9...supporting plate.

Claims (1)

[Scope of utility model registration request] A leaf spring is cantilever-supported on the main body, and an input part is connected to the middle of the displacement part of the leaf spring protruding from the main body, rising up from the displacement part at a predetermined angle toward the main body. A laminated piezoelectric element is attached to the free end of the section, and the laminated piezoelectric element deforms the entire displacement section using the fixed end of the displacement section as a fulcrum by displacing the free end using the fixed end of the displacement section as a fulcrum. A displacement mechanism characterized in that the piezoelectric element is arranged so that the expansion and contraction direction of the input section substantially coincides with the rising direction of the input section.