OPTICALLY POWERED HYDRAULIC PILOT VALVE USING PIEZOELECTRIC MULTILAYER ACTUATOR
Keywords:hydraulic pilot valve, piezoelectric actuator, power-by-light system, optical power, flapper valve, fibre optic, hazardous environment
A normally-closed 2/2 hydraulic pilot valve has been developed for a power- by-light system which is being applied in aerospace fuelling systems and oil-well applications. This system offers unique advantages such as good immunity from electromagnetic interference, intrinsic safety, and low attenuation for long distance. The valve employs a piezoelectric multilayer bender actuator (Pz29) with an elastomer blocking plate and a nozzle as the valve mechanism. The valve system is operated by 86 mW optical power which is transmitted via a multimode optical fibre (core diameter 62.5 μm) from a laser diode light source. The optical power is converted to electrical power by a photovoltaic cell, to drive the pilot valve, which requires, 8 mW electrical power to operate. The valve output flow-rate of 28 cm3/s has been achieved at an operating pressure of 1000 kPa, which is adequate for the applications. Howev-er, the maximum operating pressure up to 2000 kPa has already been tested. For the valve dynamic response, 18 ms average opening time and 1.5 seconds controllable smooth shut-off time have been observed. There was no valve opera-tion failure during vibration testing up to 196 m/s2. The pilot valve is now used to operate an aircraft refuelling valve system that provides aviation fuel flow-rate up to 680 l/min. It can also be used for other hazardous environments and noisy applications.
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