Design And Performance Research Of Servo Valve For High Pressure Common Rail Engine

With the protection of non-renewable resources and the requirements of sustainable development strategies,intelligence,greenness and energy saving have become the mainstream trends of social development.Internal combustion diesel engines are widely used in electromechanical equipment such as automobiles,ships and generators,and the development of their fuel injection systems tends to be high-precision and high-frequency response.In order to improve the control accuracy of diesel engine fuel injection,combined with servo motor direct drive technology,a servo oil distribution rotary valve for high pressure common rail diesel engine is designed,and its performance is studied.The research contents are as follows:The working principle of the servo oil distribution rotary valve is analyzed,and the overall structure scheme is determined.Based on the working parameters of the H32/40 VP high-pressure common rail diesel engine,the design goals and technical parameters of the servo oil distribution rotary valve for sequential oil distribution and flow adjustment are proposed.,the rated output flow of the valve port is calculated to be 0.101kg/stk.According to the different working conditions of the servo oil distribution rotary valve,the valve core and valve seat are designed,and the strength is checked.Three valve port models of rectangle,triangle and U shape are proposed,and the formulas for calculating the flow area of different valve port models are established,and the change curve of the flow area is obtained by analysis.According to the fluid control at the oil outlet of the valve seat,the steady-state hydraulic force,transient hydraulic force,viscous friction force and hydraulic clamping force of the valve core are analyzed,and the mechanical model of the servo oil distribution rotary valve is established.The flow field analysis model of the servo oil distribution rotary valve with three shapes of valve ports is established.Through the fluid-structure coupling analysis,it is obtained that the maximum stress of the valve core is 202.56 MPa,the maximum strain is 1.30,and the maximum deformation is 10.42 μm.The spool material is 45 gauge steel.The dynamic simulation of the pressure and output flow of the servo oil distribution rotary valve with three types of valve ports: rectangular,triangular and U-shaped,the results show that when the spool works at 1900 r/min,the rectangular,triangular and U-shaped valve ports The secondary oil distributions are 0.133,0.085,and 0.130 kg/stk,respectively.The single distribution of rectangular and U-shaped valve ports exceeds the rated value by 33%and 30%,while the single distribution of triangular valve ports is less than the rated value.Moreover,the U-shaped valve port has an obvious flow adjustment gradient at different speeds,the valve core flow channel pressure is stable,and the fluid flow rate is relatively stable,so the U-shaped valve port is preferred.Finally,the variation law of the valve port output flow,valve core axial force and torque at different axial positions of the U-shaped valve port model is obtained.