Research On Optimization Of Pre-Compensated Multi-Way Valve Through Changing Pressure Differential

Load sensing is the key technology for hydraulic systems of construction machinery to realize energy saving and improve the operating performance of actuator.At present,the domestic research on load-sensing multi-way valve technology is still not deep enough.During the process of product application,problems such as low precision of flow control,poor operating performance and limited flow range still exist.To solve these problems,an optimization method of changing the pressure differential of multiway valve is proposed,which applies additional force to the compensator spool to change its force balance state,carries on real-time control to the pressure difference,and optimizes the fretting performance,speed regulating performance and energy saving of multi-way valve.When the flow is saturated,multiple loads are decelerated in proportion by controlling the setting pressure of the compensator to realize anti-flow saturation and increase the flow control range.The specific research content is as follows:(1)Based on the constant pressure difference control principle of load-sensing system,the variable pressure differential control principle is proposed in this paper.After calculation and verification,the variable pressure differential control principle is optimized for the existing load-sensing multi-way valve CMT with front compensation valve.By adding a pressure difference control unit,additional force is applied to the pressure compensator to control the pressure differential of the main valve port.The differential pressure control unit is selected and checked,and its mathematical model is established.(2)According to the key parameters of the optimized variable pressure differential multiway valve,the simulation model of the components and the system of the variable pressure differential multiway valve is established,and the load sensitive performance,fretting performance,speed regulating performance and energy saving performance of the variable pressure differential multiway valve are simulated and analyzed.(3)Based on the variable pressure difference method,two anti-saturation strategies,PID control method and flowmeter algorithm,are proposed to control the setting pressure of compensation valve,and the control flow of the two methods is analyzed.Through the matlab/amesim co-simulation analysis,the flowmeter algorithm has better anti-saturation effect,and can ensure that the difference between the main valve pressure and the maximum load is stable at the set value when the flow is saturated,which solves the flow saturation problem of the load sensitive system in front of the actual valve compensation.(4)According to the requirements of fast response performance,energy saving and anti-saturation performance for hydraulic drive system,optimizing multi-way valve through changing pressure differential was carried out.Combined with the pressure flow characteristics of the cultivator under different working conditions,the energy saving,fast response and anti-saturation performance of the variable pressure differential multiway valve system were studied,and the feasibility of the variable pressure differential control was verified by experiments.Compared with the traditional load sensing system,the new variable pressure differential load sensing system has better energy saving and control.