Research On The Steer-by-Wire System Of Pure Electric Drive Loader

With the attention of the society to energy conservation and environmental protection,as well as the development trend of construction machinery intelligence and electro-mechanical-hydraulic integration,pure electric drive has become the most promising driving method in the field of construction machinery due to its great advantages of zero emissions and no pollution.Loaders have always been an important part of construction machinery,among which articulated loaders are the most widely used.However,the current pure electric drive articulated loader is only modified for its power drive part,and its steering system still uses the traditional structure.Steering system of traditional loaders takes a large proportion of energy consumption and has poor handling.With the expansion of the project scale and the complexity of various working conditions,the traditional steering system has been difficult to meet current engineering needs and energy conservation and emission reduction requirements.Therefore,the research on the optimization and upgrading of the steering system of pure electric drive loader is of great significance.The steering system of a traditional loader uses the steering gear as the core,and the system oil passes through the steering gear to cause a large pressure loss.Adopting an open hydraulic circuit combined with a fixed-speed and fixed-displacement hydraulic drive structure,the motor’s excellent speed regulation performance is not exerted,and the system has large throttling loss and overflow loss.Using mechanical-hydraulic joint control,the steering wheel rotation angle does not accurately correspond to the vehicle rotation angle,which brings control difficulties.Therefore,the energy-saving and controllability of the steering system of the loader needs to be improved.In this paper,a 1.6-ton pure electric articulated loader is taken as the research object.The mathematical model of articulated steering system and the virtual prototype of the whole vehicle are built,and the kinematics,dynamics and simulation analysis are carried out in depth.Based on the working principle of steering hydraulic system,a hydraulic simulation model of steering system was built to analyze the defects of traditional steering system.According to the shortcomings of the traditional steering system,a closed hydraulic circuit and a permanent magnet synchronous motor combined with a variable speed and fixed displacement system structure are proposed.Based on this structural scheme,a closed hydraulic system is designed,combined with the steer-by-wire technology,a closed pump-controlled electro-hydraulic flow matching steering system is proposed.The stability of the system is analyzed by establishing a mathematical model of a new type of steer-by-wire system.In order to further improve the energy-saving and maneuverability of the steering system,a closed-loop control strategy for the entire vehicle corner was proposed,and the feasibility of the closed-loop control of the entire vehicle corner was verified by creating an AMESim model.According to the principle of the new-type steer-by-wire system and component parameter settings,a closed pump-controlled electro-hydraulic flow matching steering system test platform was built.Set up different working conditions according to the actual engineering operation scenarios of the loader,conduct research on the energy saving and maneuverability of the system,compared to traditional steering system and the new wire control steering system,validation of new type wire control steering system energy-saving advantages The stability of the new steer-by-wire system and the tracking status of the steering signal are verified through experiments.