Characteristics Research And Optimization On Full Hydraulic Steering System With Coaxial Flow Amplification

The steering system is one of the most important systems in the vehicle,and its performances can affect the driving stability,energy consumption,operation efficiency and operation comfort.In recent years,with the development of the large-scale and high power of the construction and agricultural machinery,the requirement of the steering resistance moment increases,only using single stage hydraulic steering control of hydraulic power steering system already cannot meet the requirement of the large machinery.Full hydraulic steering system with coaxial flow amplification has the advantages of small volume,compact structure,responsive,easy install,high working reliability and higher system efficiency.It is widely used in the engineering agricultural machinery with high power.In the paper,the full hydraulic steering system with coaxial flow amplification performance simulation analysis and experimental research are carried out.It has important theory and engineering significance to improve its working stability,safety and efficiency.In the paper,based on the structure characteristics and working principle of the full hydraulic steering system with coaxial flow amplification,its steering gear,the priority valve and the combined valve block,the static characteristics are analyzed,the force balance equation and the flow continuity equation of the priority valve,the steering gear and the steering cylinder are established.According to the relative displacement relation of the valve core and the valve sleeve of the steering gear,each throttle port area is calculated.The area of each throttling port is analyzed based on MATLAB.Modeling and analysis of the steering system and its key components are carried out on AMESim.Firstly,the principle analysis of the steering gear is carried out to verify the accuracy of the steering gear model.Next the dynamic characteristics of the steering system in the different steering wheel speed,engine speed and steering load are analyzed.Finally,the influences of spring stiffness and the preload on the load sensitive characteristics of the steering system are analyzed.Based on the mechanism of the road sense and the principle of the load sensitive control,the structure of the steering system is optimized and analyzed.With the modularity design method,the road sense valve is integrated with the steering gear to get the advantages of compact structure,no leakage and convenient installation when the rotating speed of the steering wheel and the engine speed are constant,the steering load increases,the driver's steering power and labor can be reduced.Based on AMESim,the optimized steering system is modeled and simulated to verify the dynamic characteristics of the steering system after the optimization.According to the working principle and actual working conditions of the steering system,the steering performance of the steering system under different working conditions are verified and analyzed.The experimental data are compared with the simulation results,to verified the correctness of the simulation model.