Research on hydrostatic bearing technology applied in water hydraulic servo valve

Water hydraulic technology has been developing rapidly over the past decades due to its outstanding advantages, including cleanliness, security, environmental protection and cost-effectiveness and so on. At present, the research and development of water hydraulic servo valve with the performance of high precision, frequency response and high reliability become an important direction of water hydraulic technology. Hydrostatic bearing technology has been used at the both ends of the spool in order to reduce the leakage losses and form good lubrication characteristics between valve spool and sleeve in the water hydraulic servo valve. Based on hydrostatic bearing theory the mathematical model of water film pressure chamber stiffness and bearing capacity is established. Through the analysis of throttling by clearance between spool and sleeve and annular clearance in the flapper-nozzle system, the pressure-flow characteristic equation of flapper-nozzle system and the pressure characteristic equation in the case of zero flow is established, and then the equation of the clearance and nozzle between the spool and sleeve is deduced after some simulation analysis. It is shown that the application of hydrostatic bearing technology can form static pressure lubrication between the valve spool and sleeve. In addition, the linear relationship of the pressure-flow performance of the flapper-nozzle valve is maintained, but the pressure performance of which become worse. Therefore, it's necessary to select the linear district reasonably.