Design And Experimental Study On Active Steering System Of Distributed Drive Electric Bus

The sustainable development of China's automobile industry is facing the dual challenges of energy security and environmental pollution,and the energy conservation and emission reduction task of the automotive industry is very arduous.Low carbonization and electrification of automobiles have become the world's common strategic choice to respond to energy and environmental challenges and occupy the industrial high ground.China has fully implemented the "pure electric drive" technology transformation strategy.The multi-axis distributed pure electric powertrain system has become the development trend of city bus technology,with its flexible layout,strong bearing capacity,high efficiency,zero emission,low energy consumption and other superior performance.For the multi-axis distributed pure electric powertrain system,there are serious problems such as serious tire wear,large turning radius,poor handling stability and etc...Through the analysis of the tri-axial distributed pure electric powertrain system,the third axle had a great impact on the vehicle handling and its passing.Currently,the steering system of the third axle usually adopt passive steering technology.In the practical application,the third follow-up axle generally existed the following problems,when the reclining angle is too large,the steering torque will be too big,and will result in the difficulty of the turn back of the follow-up axle;when the reclining angle is too small,the steering torque will be too small,the reverse torque generated by frictional resistance around the main pin axis could not be overcome,resulting in the reaction hysteresis of the follow-up axle,increased turning radius,reduction of vehicle steering sensitivity,and exacerbation of the tires abnormal wear.Take the distributed pure electric city bus as the research object,the electromechanical hydraulic active steering system was designed.The electronic control hydraulic power steering system is adopted in the front axle,and is controlled by the driver turning the steering wheel.The electromechanical hydraulic active steering is added in the third axle and is controlled by the active steering control unit,to realize the active steering function of the third axle,improve the handing stability,reduce the turning radius and tire wear and improve the tire life of the vehicle.