Jet Pipe Servo Valve Research Articles

Investigation on the Prestage of a Water Hydraulic Jet Pipe Servo Valve Based on CFD

In a water hydraulic jet pipe servo valve, the overall performance of the valve is directly influenced by the structure dimension of the receiver and the prestage— jet pipe amplifier. This paper deals with the influence rules of the structure dimension parameters and performance parameters on the buildup pressure in the two receiving holes, including the vertical clearance between the nozzle and the receiver, the diameter of the nozzle hole, the diameter of the receiving orifice, and the nozzle offset distance. The best combination of structure size is finally obtained by using numerical simulation, computer emulation and experiment analysis methods. Then build up the finite volume analysis models about the pressure field and the speed field of the jet pipe amplifier. Through analyzing the characteristics of the flow field, a mathematics relation between the jet nozzle offset and the pressure ratio inside the two receiver holes is established, which reveals the energy distribution and conversion mechanism. The conclusion could be an important reference for the design and research of jet pipe servo valve.

Depression of Self-Excited Pressure Oscillations and Noise in the Pilot Stage of a Hydraulic Jet-Pipe Servo-Valve Using Magnetic Fluids

Magnetic fluid (MF) shows an increased saturation magnetization when exposed to a magnetic field. In order to improve the quality of servo-valve products by depressing and overcoming the self-excited high-frequency pressure oscillations and noise appearing in pilot stage of a hydraulic servo-valve, application of magnetic fluid in a hydraulic servo-valve is developed in this paper. Large damping can be introduced by the magnetic fluids into the servo-valve if magnetic fluids are filled into the working gaps of the hydraulic servo-valve torque motor. After the construction and working principle of a hydraulic servo-valve with magnetic fluids are introduced, the high-frequency pressure oscillation signals are tested and recorded when magnetic fluids are applied or not in the servo-valve. Experimental results are compared and analyzed by using FFT analysis method. It is shown that pressure oscillations of the servo-valve are depressed when magnetic fluids are applied.

Simulation investigation on fluid characteristics of jet pipe water hydraulic servo valve based on CFD

Simulation investigation on fluid characteristics of the water hydraulic jet pipe servo valve (WHJPSV) is con- ducted through a commercial computational fluid dynamics (CFD) software package FLUENT. In particular, the factors to fluid characteristics of WHJPSV are addressed, which include diameter combination of jet pipe and receiver pipe, jet pipe nozzle clearance, angle between two jet receiver pipes and deflection angle of the jet pipe. It is concluded from the results that: (i) Structural parameters have great influences on fluid characteristics of WHJPSV, when d1 = d2 = 0.3 mm, α =4 5 ◦ , b = 0.5 mm, and the simulation exhibits better fluid characteristics; (ii) The magnitude of the recovery pressure and flow velocity increase almost linearly with the deflection angle of jet pipe. The research work in this paper is important for deter- mining and optimizing the structural parameters of the jet pipe and jet receiver. The relevant conclusions could be extended to the study of other water hydraulic servo control components.

Research to the Wear and Geometric Error Relations of Electro hydraulic Servo Valve

The working principle, failure modes and failure causes of the jet pipe servo valve has been analyzed. Get the main failure modes of the servo valve, which is caused by wear. The influences of the arris edge geometric error on the performance of the servo valve been analyzed. Get the wearing capacity equal to the edge arris geometric error. It provides an estimation method of the arris edge geometric error, which could be use to analysis the wearing capacity of the servo valve.

Steady-state analysis of a precision hydraulic flow control servovalve using the finite element method

In the present paper, an attempt has been made to simulate the steady-state operation of the jet pipe Electro-Hydraulic ServoValve (EHSV) using the Finite Element Method (FEM). The jet pipe servovalve has two stages and consists of two main assemblies: first-stage torque motor assembly and second-stage valve assembly. Between the first and second stage there is a mechanical feedback to stabilize the valve operation. Each assembly has various delicate and precise components. The finite element analysis has been carried out on jet pipe and feedback spring assembly. The analysis shows that the stiffness of flexure tube and feedback spring assembly plays the major role in achieving steady-state valve operation. The stiffness of these components is obtained through the FEM and these results are validated with experiment. The commercial ABAQUS finite element code has been used for the simulation. The mathematical model of the jet pipe EHSV has been developed and simulated using MATLAB to study the spool dynamics with the main emphasis on the steady-state valve operation. The required simulation parameters, like moment of inertia, stiffness of the components and lever arm length. are obtained from the FEM.