Servovalve Fluid Measuring System Based On The Spool Valve Flow Pressure Characteristics

Spool valve is an hydraulic actuator which makes use of the sharp-edged orifice between the spool and the sleeve for throttle control. Due to its excellent flow characteristic, it is used as the servo-valves' power output stage. Through spool axial displacement, the spool valve changes the orifice size to control the flow output. Therefore, the spool valve overlap value becomes key indicators during the spool manufacturing process. The tolerance of overlap is 1?m and can't be interchanged. At present, the fluid method is widely adopted to measure the overlap value. The Fluid Measuring method, based on the theory of the outflow through sharp-edged orifice formula and considering the aviation hydraulic oil as its measuring medium, has a broad application prospect.Production practice shows that some of the spools' overlap value fulfills the design requirement, but the pressure gain and the internal leakage of the servo valve will be out of specification during servo valve testing. Therefore, it is necessary to study the pressure and leakage characteristics of the spool valve to connect them with the valve overlap value and further guide the Fluid Measuring.First, the thesis studies different orifices' flow models and further builds the entire flow field model of the spool valv e. Combined with COMSOL's simulation analysis, it focuses on the impact of geometrical factors to the whole spool valve flow pressure characteristics.Second, a new Fluid Measuring system with wide application range(100-1200L/min) is developed. Under the circumstance of meeting the measurement accuracy and stability demands, the newly developed system improves the application scope and realizes multi-index measurements, such as the valve overlap value, internal leakage and pressure gain. At the same time, the thesis uses automated measurement software written by VC, utilizes SQL server to store measurement data and finally achieves the goal that the whole valve characteristic curve directs the overlap value's Fluid Measuring.Finally, the experimental research is carried out to test the performance of new Fluid Measuring system and accomplish the spool valve's flow and pressure characteristics experiment.