Research On Dynamic Characteristics Of Pilot-operated Piston Shut-off Valve Spool

With increased emphasis on green car issues, automobile exhaust emission limits more stringent, and three-way catalytic converters'(TWC) cleaning and repair become the focus of attention. In the cleaning process, it requires high performance control valves. But the general pilot-operated piston cut-off valve's corrosion resistance and open performance is difficult to meet process requirements, and seriously affecting the cleaning efficiency and overall quality of the device.In this paper, according to the demands of actual working conditions, to improve valve performance is research objective. According to the continuity equation, energy conservation equation, we set up and analyze mathematical model of original pilot valve, and inferred main factors that had affect the dynamic characteristics of the valve. We put forward the improved structure of the spool which had open diversion tank, and correct mathematical model of original pilot valve. For improvement program for the spool and the main influencing factors, we use AMESim software to build dynamic simulation model of the original valve and the valve that had open diversion tank. Through analyzing dynamic simulation results, we verify the superiority of improvement program. At the same time, we had established digital prototypes of the original valve and the valve that had open diversion tank. For critical state of pilot spool opens, we made flow field simulation analysis by using dynamic mesh of simulation software CFD. And we further verify accuracy and reliability of analysis results and dynamic simulation. Finally, we verified reliability of analysis results and dynamic simulation by experimental methods, verified accuracy of the spool movement characteristics of law of structural parameters.Through the above study, we had get a mathematical model of the improved pilot valve, put forward the concept and expression of diversion coefficient. The results show that the improved pilot valve relative to the original pilot valve, the spool suffered larger pressure forces and open time had shortened by 5.62%; according to the state of the valve, the flow channel cross-sectional shape preferably semicircular guide preferably 4 launder distribution average; and when the percentage of diversion area occupy an area of the valve chamber at 6.28%, the best performance of the valve open.