Piezo stack actuation has excellent and unique characteristics that allow unusual problem solutions. Piezo are used for scientific instrumental techniques with atomic resolution. It is also in everyday uses such as ignitors lighters and piezoelectric controlled fuel injectors in automobile engines. Proven are piezoactuators for antivibration and anti-sound systems. In general, the applications can be divided into four fields:
· Voltage transformation,
· Energy harvesting,
Piezo stack actuator technology enables a multitude of different types: linear positioning, linear and rotary motors, drives for pumps, pneumatic and hydraulic valves, injection nozzles, dispensers, vibration sources (shakers) for sound and dynamic power generation, also for noise and vibration damping, diverse mechanisms optical technology, material and component testing, speakers, inkjet printers, and finally energy harvesting.
Piezoelectric stack transformers are very useful for the generation of high voltages. A piezoeletric transformer is a ceramics block with two functional sections. Each section has a electrode structure. The first section is for the voltage input whereas the second provide the output. The electrode spacing of both electrode structures is different and defines the transformation ratio. The unit is operated in mechanical resonance at quite high frequency to increase power density. The energy is converted twice: The electrical input power is converted in the first piezo section to mechanical power and excites resonance of the whole piezo body. The second functional section transforms the mechanical power to electrical power and the voltage taken form the electrode structure with much larger spacing the exciter electrode. These units demonstrate both piezo effects, the direct and reverse. The advantages of the units are small size and high efficiency for high voltage power generation in the range of Watts.
The piezo effect describes the generation of electric energy form mechanical deformation. If oscillations are present, stacks can be attached to the vibrating structure (e.g. a machine) to generate electrical power. The energy of mechanical deformation, the frequency of the vibration, and the efficiency of the electro-mechanical coupling of the piezo material determine the output power of the described piezo generator. Piezo stack actuators from Piezotechnics are perfect for designing such elements. The achievable output power depend on the available mechanical power, the mechanical deformation of the attached piezo and the frequency. Piezo generators are suitable for supplying small electrical loads and applications such as remote sensors have been successfully demonstrated.
Piezo stacks are perfect for dynamic sensor applications such as acceleration and force measurement. Forces, which act on a piezo stack, cause the displacement of the charges in the crystal structure of the material and a voltage signal across the terminals is generated. Piezo stacks from Piezotechnics generate quite high usable voltage output and allow direct measurement without amplifiers is possible. The limits of these excellent sensors are the low frequency response. In this situation quartz materials are preferable.
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