JP2002252989A - Piezoelectric power generating unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric power generating unit which generates large power and is high in reliability. SOLUTION: In a piezoelectric bimorph in which a piezoelectric element is fixed to a part of a single rectangular or bar piezoelectric element or an elastic body, a mechanism for fixing the piezoelectric element or the piezoelectric bimorph to a node of a bending vibration of the piezoelectric element is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a vibration or a shock by vibrating a piezoelectric bimorph or a piezoelectric unimorph, or for lighting a light emitting element or the like by using the generated power, or for reusing a secondary battery. The present invention relates to a power generation device using a piezoelectric element, such as charging and using the same.

[0002]

2. Description of the Related Art Conventionally, when power is generated by a piezoelectric element of this type, a plate-shaped piezoelectric ceramic element is formed by forming electrodes on a paired surface having the largest area, and is laminated with a thin elastic body. Piezoelectric unimorph elements or piezoelectric ceramic elements are connected directly or via an elastic plate.
A piezoelectric bimorph element obtained by laminating pieces is used. In this case, as a method of supporting the element, one end is fixed and a method of applying an external force to the free end, or the periphery of the elastic body that protrudes around the ceramic element is fixed, and an impact body such as a metal ball or a ceramic ball is fixed. A method has been used in which power is generated by colliding with a ceramic portion by a piezoelectric positive effect of a piezoelectric element. The electric energy obtained in this manner is used for light emission of a light emitting body, or a secondary battery is charged and taken out for use.

In Japanese Patent Application Laid-Open No. Hei 6-209807, this power generator is mounted on the sole of a shoe, and an impact body incorporated by reciprocating left and right or up and down strikes a piezoelectric element to generate electricity in accordance with a walking or running motion. The invention which makes the luminous body emit light is disclosed. Japanese Patent Application Laid-Open No. 2000-287664 discloses a similar invention, in which an impact body in a guide collides with a piezoelectric element from vibration during bicycle running to generate distortion, thereby obtaining electric energy and emitting light with this energy. There is disclosed an invention relating to a bicycle capable of driving safely by lighting a diode.

In the above invention, the piezoelectric element is fixed by supporting at least two locations on the outer periphery, thereby realizing the bending state of the beam when receiving an impact, thereby increasing the power generation efficiency. However, in the piezoelectric power generation, the contribution to the power generation efficiency is not limited to not only the distortion at the time of impact but also the electric energy generated at the time of the subsequent damped vibration. Therefore, as a holding condition, in the case of a rectangular bimorph or unimorph vibrator, it is desirable to support two points at a vibration node where damping vibration can be continued as long as possible.

On the other hand, it is relatively difficult to mechanically support the two vibration nodes of the vibrator which receives an impact, the support mechanism is likely to be damaged by the impact of the impact body, and As a result, there has been a problem that the impact on the element is reduced and the power generation performance is reduced. In addition, due to this support structure, there is a problem that the configuration becomes complicated and the number of parts increases, so that there is a problem that the mass productivity is reduced and the manufacturing price is increased, and the appearance of a simple and highly reliable support structure has been desired. .

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to eliminate this drawback by adding a vibrator-joining elastic part for a piezoelectric unimorph, an elastic part of an intermediate layer for a piezoelectric bimorph, and a bending vibration node part for these elements. Supporting columns for supporting, and a frame for fixing the whole are composed of a piezoelectric unimorph unit or a piezoelectric bimorph unit formed by punching out an elastic body plate, which is robust and does not interfere with the impact of the impact body. It is an object of the present invention to provide a piezoelectric power generation device that has a small number of points and is easy to produce, and that efficiently converts strain energy due to impact into electric energy.

[0007]

SUMMARY OF THE INVENTION In order to eliminate this drawback, the present invention eliminates this problem by using a vibrator-bonded elastic part for a piezoelectric unimorph, an elastic part of an intermediate layer for a piezoelectric bimorph, and a bending vibration for these elements. A piezo-electric unimorph unit or piezo-bimorph unit is formed by punching an elastic plate integrally formed with a support for supporting the node portion and a frame for fixing the whole, and this is used for a piezoelectric generator.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

Hereinafter, the piezoelectric bimorph will be described. However, if the piezoelectric ceramic plate to be joined is composed of only one side, a piezoelectric unimorph will be obtained, and the description of the unimorph will be omitted.

FIGS. 1 and 2 are a part view and an assembly view showing an embodiment of the present invention.

FIG. 1 shows components of an embodiment of the present invention. Each component is completed by the following configuration.

Reference numeral 1-1 denotes a piezoelectric ceramic element. In this embodiment, a zircon-lead titanate-based material is used as the piezoelectric ceramic, but a barium titanate-based piezoelectric ceramic material may be used. Reference numerals 1 and 2 denote piezoelectric ceramic elements and a holding plate used when the piezoelectric ceramic elements are sandwiched between metal sheets. In this embodiment, a 0.2 mm stainless material etched is used. About this holding plate, not only stainless steel but other metal materials such as copper,
Further, it is possible to use an organic material such as glass epoxy.

[0013] 1-3 are piezoelectric ceramic elements similar to 1-1. Fig. 2 is a figure? The present invention will be described in detail with reference to FIG. 1 (parts diagram) and FIG. 2 (assembly diagram) showing a bimorph structure in which the components shown in FIG.

FIG. Reference numeral 1 denotes a component configuration for realizing the present embodiment. According to this, the component is composed of two piezoelectric ceramic elements (1-1, 1-3) and a holding plate (1-2) for forming a piezoelectric bimorph structure. At the time of this bonding, the polarity of the piezoelectric ceramic element has the same polarity with respect to the holding plate (1-2). As for the holding plate, a portion (length L1, width W1) functioning as a piezoelectric bimorph with a piezoelectric ceramic element attached thereto, a portion (length L2, width W2) disposed so as to surround the portion and a bridge therebetween. (Length L3, width W3). The position (a) of this bridge is a position obtained from the following formula with respect to the length L1.

A = L1 × 0.224

This position is a node point of the primary flexural vibration of the piezoelectric bimorph and does not restrict the vibration of the piezoelectric bimorph. By not restraining the piezoelectric bimorph, the damped vibration of the piezoelectric bimorph after the impact is prolonged, and electric energy by the piezoelectric can be efficiently extracted. As a result, in fixing the piezoelectric bimorph portion, it is possible to hold the piezoelectric bimorph without restricting the vibration of the piezoelectric bimorph even if the holding portion (length L2, width W2) surrounding the outer periphery of the bridge is fixed.

FIG. 2 is an assembly diagram in which the components shown in FIG. 1 are bonded with an epoxy resin or an anaerobic adhesive. According to this, the functional elements of this assembly are divided into three parts. One is a portion that functions as a piezoelectric bimorph (length L1, width W1), and the other is a portion that is arranged to surround as a fixed function (length L2, width W2) and 3
The first is the part that has the function of bridging them (length L3, width W3).

Parts as fixed functions (length L2, width W2)
Is fixed by a fixing method such as bonding or screwing, and by applying an impact to the piezoelectric bimorph portion (length L1, width W1), electric energy can be extracted from the electric terminals at both ends of the piezoelectric bimorph due to the piezoelectric positive effect. .

This impact causes the piezoelectric bimorph to bend and vibrate, generating electric energy from the piezoelectric bimorph and extracting electric energy from the electric wire connected to both electrodes. Here, the piezoelectric bimorph is supported by a bridge (length) at the node of the flexural vibration of the piezoelectric bimorph.
L3, width W3), and the amount of electric energy generated by the piezoelectric bimorph hardly decreases due to the influence of the fixed portion.

As described above, electric energy can be more efficiently generated from the piezoelectric bimorph, and electric energy can be extracted from both electrode terminals via electric wires. The above-described series of configurations shows that electric energy can be efficiently supplied to a load by preventing a decrease in the amount of generated electricity due to the method of fixing the piezoelectric bimorph.

The electric energy generated from this is connected to a load and performs work. In this embodiment, the load is a light emitting diode, which is finally converted into light emission energy. However, the load is not limited to the light emitting diode.

In each of the power generation units according to the embodiments, an AC voltage is generated. Therefore, if necessary, rectification is performed by a rectifier circuit to take out a DC current, or a capacitor is connected in parallel with a load to generate a generated voltage. Can be used after smoothing.

[0023]

As described above, according to the present invention, the piezoelectric element used in the piezoelectric bimorph, the portion holding the piezoelectric element, and the bridge mechanism for fixing the node part of the flexural vibration can be used to prevent the piezoelectric bimorph from being subjected to impact or the like. When distortion is applied, this can be efficiently converted to electric energy, and the number of types of fixing methods as a unit increases, so that the degree of freedom in design can be increased. Also, the reduction in the number of parts can increase production efficiency and contribute to a reduction in manufacturing costs. Furthermore, with a robust configuration, the impact body is less likely to be disturbed and the reliability against repeated impacts is improved, and a highly reliable and highly efficient power generation unit can be provided.

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of the present invention. 1-1 Piezoelectric element 1-2 Holding plate 1-3 Piezoelectric element

FIG. 2 is a front view showing the first embodiment of the present invention. 2-1 Piezoelectric element 2-2 Holding plate 2-3 Piezoelectric element

Claims (2)

[Claims] 1. An intermediate layer part of a piezoelectric bimorph element, a support part for supporting a node part of a bending vibration of a general element, and a frame part for fixing the whole are formed by punching an integral elastic plate. A piezoelectric bimorph unit and a piezoelectric generator using the same. 2. An elastic plate integrally formed with a vibrator-joining elastic portion of a piezoelectric unimorph element, a support portion for supporting a node portion of a bending vibration of a general element, and a frame portion for fixing the whole. A piezoelectric unimorph unit characterized by being formed by the above method, and a piezoelectric generator using the same.