Study On The New PWM High Speed On-off Valve

Digital electric-hydraulic governor has become the future direction of development of the turbine governor for its advantages of highly intelligent, fast dynamic response, small steady state error and strong anti-jamming capability etc.High speed on-off valve is the core component in digital electric-hydraulic governor, it has many merits such as high response speed, good ability of resisting contaminated oil and capability of assorting well with electrocircuit. The performance of high speed on-off valve exerts direct influence on the control performance of the turbine governor system. There are many shortcomings of existing high speed on-off valve, such as small output flow and slowly speed of response, it can not meet the control requirements of the turbine governor system. This paper aimed at the functional requirements and technical specifications of the turbine governor system for high speed on-off valve, we designed the new PWM high speed on-off valve. The valve use single-nozzle flapper valve as the pilot stage, the ball valve as the power stage of main valve, according to structural design and theoretical analysis of the valve, making it meet the control requirements of the turbine governor system.The main contents of this paper are as follows:(1) According to the specifications and functional requirements of the PWM high speed on-off valve, we designed the specific structure of high speed on-off valve. The valve use PWM as the control mode, use high frequency electromagnet to driving baffle of single-nozzle flapper valve directly for high speed movement, making the piston of differential hydraulic cylinder push case of main valve switching fast under the effect of differential pressure, then achieve the fast connect and break of inlet and outlet.(2)Numerical analysis on the main valve and nozzle flapper valve flow field of PWM high speed on-off valve by the Fluent software, obtaining the streamlined graph, pressure and velocity cloud graph of the flow field. According to analyze different dimensions and boundary conditions of the flow field, finding out the relevant factors of affecting the characteristics of high speed on-off valve flow field, providing design basis for choosing the structure size of the valve reasonable.(3) This paper analyzed the static and dynamic characteristics of PWM high speed on-off valve. On the basis of dynamic mathematical model of high speed on-off valve, using the Simulink tool of Matlab to establish the time-domain simulation model of PWM high speed on-off valve, then completed the numerical simulation of its dynamic characteristic; We also analyzed various factors which affect the dynamic characteristic of high speed on-off valve, fixed the structure size of high speed on-off valve major components.The developed PWM high speed on-off valve in this paper, preferably solves the problem that the normal high speed on-off valve has the problems of slow response speed and small output flow, it meets the control requirements of the turbine governor system, and has some use value and a wide range of application prospect.