JP3489619B2 - Piezoelectric generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric generator using a piezoelectric ceramic element. [0002] As is well known, piezoelectric materials have a variety of applications for converting elements between mechanical energy and electrical energy. Many inorganic and organic materials exhibiting the piezoelectric effect are known, but PZT (piezo) ceramics are currently in practical use.
Materials such as electric ceramics are known. A piezoelectric ceramic element is an element in which a high DC voltage is applied to a polycrystalline body to generate remanent polarization and thereby impart piezoelectricity. Since the basic piezoelectric constant can be changed considerably freely depending on the composition, Its application is wide. In particular,
Zinc titanium zirconate-based piezoelectric ceramic elements have a wide selection range of composition ratios and additives, and have a wide range of application. FIG. 2 is an explanatory view of a conventional piezoelectric generator. In this piezoelectric power generating device, a piezoelectric ceramic element 2 is joined to a metal substrate 1 and both ends of the substrate 1 are fixed by holders 3 made of a hard material such as metal. And
A steel ball 4 is dropped from above the metal substrate 1 to apply mechanical impact energy due to collision to the piezoelectric ceramic element 2,
It excites the flexural vibration of the piezoelectric ceramic element 2 including the substrate 1 to extract electric energy. [0005] However, in the above-described conventional piezoelectric power generating device, the center of vibration (the portion that does not expand and contract) is located because the substrate 1 and the piezoelectric ceramic element 2 are made of different materials. Since the substrate 1 and the piezoelectric ceramic element 2 are joined without being set on the joining surface, when the center L of the vibration appears on the piezoelectric ceramic element 2 side, polarization cancellation (D1 = D2) occurs. hand,
Eventually, the amount of distortion in the portion D3 becomes the amount of power generation, so that there is a problem that the power generation efficiency is greatly reduced. The present invention has been made in view of the above situation, and an object of the present invention is to greatly improve the power generation efficiency of a piezoelectric power generation device having a single-layer structure of this kind. Therefore, it is intended to provide a piezoelectric power generation device which can simplify the structure of this type of piezoelectric power generation device, can be miniaturized and can be used for various purposes, and can be manufactured at low cost and has excellent power generation efficiency. Is what you do. In order to achieve the above object, according to the present invention, a metal plate is joined to a piezoelectric ceramic element to form a piezoelectric ceramic body, and the piezoelectric ceramic element or metal Based on the technical premise of a piezoelectric generator capable of generating electricity by applying a collision load to the plate, the amount of strain deformation of the metal plate and the amount of strain deformation of the piezoelectric ceramic element
To balance by adjusting the thickness of the metal plate
With both ends of the piezoelectric ceramic body closed.
And the center point of vibration in the state where the piezoelectric ceramic element and the metal plate are joined and held ,
It is characterized in that it is set at the joint surface between the piezoelectric ceramic element and the metal plate. The present invention will be described below in detail based on an embodiment shown in the accompanying drawings. FIG. 1 shows a schematic configuration of a piezoelectric power generating device according to an embodiment of the present invention. The piezoelectric power generating device has a piezoelectric ceramic element plate 12 bonded to a metal substrate 10 and a substrate. Both ends of the piezoelectric ceramic element plate 10 and the piezoelectric ceramic element plate 12 are adhered and held by cushion materials 11, 11 via a holder 13 made of a hard material such as metal. The amount of strain deformation of the metal substrate 10 is set so as to be balanced with the amount of strain deformation of the piezoelectric ceramic element 12 by adjusting the thickness of the metal substrate 10. 12 and metal substrate 1
The center point L of the vibration in the state where 0 is joined is
It is set so as to be a bonding interface between the piezoelectric ceramic element 12 and the metal plate 10. [0011] Therefore, in this embodiment, by colliding the <br/> et steel balls 14 or either side of the metal substrate 10 or the ceramic element 12, the mechanical shock energy generated by the collision This is applied to the piezoelectric ceramic element 12 to excite flexural vibration in the piezoelectric ceramic body A including the substrate 10. At this time, since the vibration generated in the piezoelectric ceramic element 12 is not canceled out by the vibration of the metal substrate 10 , most of the bending vibration around the bonding surface which is the center point L of the vibration is converted to electric energy. It can be taken out efficiently. The generated electric current as electric energy is taken out using the lead wire 19. In this embodiment, a protector plate (not shown) made of metal or synthetic resin is fixed to the piezoelectric ceramic body 12 so as to improve durability. You can also. Although the outer shape of the piezoelectric ceramic body 1 is not particularly limited, the front shape may be a circle, an ellipse, a triangle, a square, a polygon, or the like. Further, the cushion material 11 is made of a synthetic resin material, a rubber material, or a sponge-like soft material. By using such a cushion material 11, the vibration of the piezoelectric ceramic body A can be prevented from being attenuated. When the piezoelectric ceramic body A vibrates, the member supporting the piezoelectric ceramic body A becomes a factor for attenuating the vibration of the piezoelectric ceramic body A,
In order to remove this damping factor, it is desirable to keep the piezoelectric ceramic body A as free as possible using the cushion material 11. By using the cushion material 11 in this manner, the natural vibration of the piezoelectric ceramic body A lasts for a long time, so that the power generation efficiency is improved. In addition, this cushion material 11
Reduces the impact applied to the piezoelectric ceramic body A. If the above-described piezoelectric power generating device is placed in an environment of a predetermined motion state utilizing wind, waves, or human action, impact energy acting on the piezoelectric ceramic body A is applied. Is done. Then, the vibration of the piezoelectric ceramic body A is excited, and the expansion and contraction are repeated, thereby generating AC electricity. In the case of using the above-described piezoelectric power generating device to charge the electricity generated by the power generating device, although not shown, PZT constituting the piezoelectric ceramic element 12, a required number of rectifying diodes, and electricity are stored. It is appropriately composed of a capacitor, a switch and a required number of light emitting diodes. P
The electricity generated by the ZT is full-wave rectified by the diode. This full-wave rectified electricity is charged to the capacitor. By operating the switch, the capacitor is discharged to light each light emitting diode. As described above, in the piezoelectric power generating device according to this embodiment, the piezoelectric ceramic element 12 has a single-layer structure,
In addition, since there is no fear that the vibration generated in the piezoelectric ceramic element 12 is canceled out, most of the bending vibration can be efficiently taken out as electric energy around the bonding surface which is the center point L of the vibration, so that the power generating device can be used. The configuration is extremely simplified, the whole device can be reduced in size, and the manufacturing cost can be reduced, so that practical applications are further expanded. For example, if this piezoelectric power generation device is mounted on a bicycle or shoes, and the light emitting diode is turned on, it can be used as a device for recognizing the presence at night. Further, if the battery is mounted on a battery-type wristwatch or a mobile phone, it can be used as a substitute for a battery or as a measure against running out of a battery. Furthermore, by generating electricity using the sway of the waves, use as a lighting device for a buoy (buoy) can be expected. Further, it is also possible to adopt a configuration in which electricity is stored until a constant voltage is reached, and when the constant voltage is reached, the stored electric energy is released at a stroke. As described above, according to the piezoelectric generator of the present invention, the amount of strain deformation of the metal plate and the piezoelectric ceramic
Adjust the amount of strain deformation of the metal element by adjusting the thickness of the metal plate.
And the piezoelectric ceramic
Since both ends of the mixed body are held by the cushioning material, and the center point of the vibration in a state where the piezoelectric ceramic element and the metal plate are bonded and held is set at a bonding interface between the piezoelectric ceramic element and the metal plate, power generation is performed. efficiency is significantly improved, with an effective power generation device can be obtained in the low power generation, it is possible to reduce the number of parts, it is possible to realize a reduction in size and manufacturing cost, moreover, the piezoelectric cell
I hold both ends of the Lamix body with cushioning material
Therefore, the vibration of the piezoelectric ceramic body lasts a long time ,
It has an excellent effect of being greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a schematic configuration of a piezoelectric generator according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a piezoelectric generator according to a conventional example. [Description of Signs] A Piezoelectric ceramic body L Center point of vibration 10 Metal substrate 11 Cushion material (cushion plate) 12 Piezoelectric ceramic element 13 Holder 14 Steel ball

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-49388 (JP, A) JP-A-5-64418 (JP, A) JP-A-55-20459 (JP, A) JP-A-2000-287464 (JP, A) JP-A-2001-145375 (JP, A) JP-A-9-191664 (JP, A) JP-A-11-275875 (JP, A) JP-A-51-115074 (JP, U) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H02N 2/00 H01L 41 / 113,41 / 187

Claims (1)

(57) [Claims 1] A metal plate is bonded to a piezoelectric ceramic element to form a piezoelectric ceramic body, and power can be generated by applying a collision load to the piezoelectric ceramic element or the metal plate. In a piezoelectric generator, the amount of strain deformation and pressure of the metal plate
The amount of strain deformation of the ceramic element is determined by the thickness of the metal plate.
By adjusting the
Hold both ends of the piezoelectric ceramic body with cushioning material,
The piezoelectric power generating device, characterized in that the piezoelectric ceramic element and the metal plate to the central point of vibration in the state of being bonded and fixed, was set on the bonding boundary surface between the piezoelectric ceramic element and the metal plate.