Research On Matching Method Between Multi-way Valve And Pilot Valve For The Work Device Of The Wheel Loader Hydraulic System

The hydraulic multi-way valve and pilot valve are widely applied in theconstruction machinery. The pilot valve is used to control the valve spool movement,which can reduce the control force of the handle. Increasing the stiffness of the springcan offset the effect of the fluid dynamic to the movement of valve spool. However，the loader operation comfort largely depends on the matching characteristic of pilotvalve and multi-way valve, the micro performance of working device and the freestroke of pilot valve.This paper takes pilot valve and multi-way valve on a type of loader as researchobjects. The internal structures of the pilot valve and the multi-way valve were deeplyanalyzed, the relation between the pilot valve displacement pressure curve, multi-wayvalve displacement pressure curve and the multi-way valve displacement flow curvewas deeply studied. In addition, the relation between the pressures at the start positionand the end position of the pilot valve and the opening of multi-way valve wasdetermined, the relation between the pilot valve displacement and the multi-way valveflow was finally confirmed, and the matching principles and methods of pilot valveand multi-way valve were proposed.The models of multi-way valve and pilot valve were established using AMESim,and dynamic simulation of the opening processes of the multi-way valve spool andthe pilot valve spool were conducted. Various factors affecting the performance of thepilot valve and multi-way valve were analyzed. On this base, the matching ofmulti-way valve and pilot valve was optimized and critical parameters weredetermined.The optimized multi-way valve and pilot valve was tested again to verify thedifferent optimization effect.According to the comparison, the testing curve and thesimulation curve are closely identical, which shows the models are accurate. Theresearch results in this essay offer new methods for the matching of multi-way valve and pilot valve, which is not only practically significant for the pilot hydraulic systemdesign of loaders, but also valuable and instructive for the study of pilot hydraulicsystem design for all construction machinery industry.