Research On Oil Compensation Method For Internal Leakage Of Electronic-control Full-hydraulic Steering System

Full hydraulic steering system uses hydraulic power for its steering operation,and there is no mechanical connection between steering wheel and steering mechanism.Since there is no mechanical connection for accurate positioning,and exists internal leakage in the hydraulic components,positional relationship between steering wheel and ground wheel is not one-to-one correspondence during steering operation,steering wheel has a certain slip relative to ground wheel when forklift returns,which makes it difficult for the driver to memorize the position of handle ball of steering wheel,causing inconvenience for steering operation.Electronic-control full hydraulic steering system can ensure accurate corresponding relation between steering wheel and ground wheel during steering process by conducting oil compensation,which allows driver to operate forklift more conveniently and accurately.On the basis of oil compensation method for internal leakage in hydraulic redirector,the research of this paper mainly discussed accurate corresponding relation between steering wheel and ground.Main contents in this article are as follows:Used forklift as research object,qualitatively analyzed internal leakage characteristics of full-hydraulic steering system,and designed a new kind of electrocontrol full-hydraulic steering system,meanwhile,analyzed its control principle,compensation principle and compensation working conditions.Analyzed influence factors on internal leakage of full-hydraulic steering system,established mathematic model of the system,and used Matlab/Simulink software to respectively analyze effect degree of gap between valve pocket and valve body,oil temperature and pressure difference on internal leakage of the system.In order to verify compensation function of the designed system,in extreme working conditions,according to different steering wheel speed,simulated oil volume entering into hydraulic cylinder,oil internal leakage volume,and angle error.By comparing the steering precision of before and after the electro-control oil compensation system was enabled,feasibility of the designed electro-control oil compensation scheme was verified.According to the requirements of its function,used STC15F2K60S2 MCU as the core to design controller,drew circuit schematic diagram of all function modules of the controller and designed its printed circuit board,which was used as the hardware platform of compensation system.In addition,designed algorithm for oil compensation,then completed programming of all function modules in Keil C51,to accomplish data communication between the controller and human-computer interface,data processing,and solenoid valve control.Used forklift as experimental platform,confirmed standard proportionality coefficient between steering wheel and ground wheel of compensation algorithm through the collected data.Then testing the forklift when conducted pivot and dynamic steering,based on the available conditions,in different temperature and speed of steering wheel,before and after the electro-control oil compensation system was enabled,testing angle of steering wheel when the ground wheel returned,or arriving at the range of ±2° of its zero position.By comparing the results of before and after the system was enabled,function of the designed system and its stability was confirmed.