A Study On Steering Behaviour Of The Bogie With Independently Rotating Wheels

With the development of the technologies of independently rotating wheels (IRW), the bogies with IRW have been applied widely on light rail vehicles and gauge-changeable vehicles. The IRW has become an important research direction for the vehicle running gear technology.Comparing with the conventional solid wheelset, the IRW has no hunting motion and the vehicle system can possess higher stability due to zero longitudinal creep force. But the self-steering capability of the IRW bogie is low because of the lack of longitudinal creep moment. This shortage limits the use of IRW. How to improve the guidance and steering capability of IRW is a difficult problem. Many countries have developed different kinds of bogies with IRW to solve the difficulties of the steering problem and formed various development patterns.The lateral-coupled IRW bogie and the longitudinal-coupled IRW bogie have the advantages of simple structure, relative low cost, and are widely used in light rail vehicles. The longitudinal-coupled IRW bogie also has the advantages of easy dismount of traction motor and convenient maintenance, and is widely used in 100% low floor light rail vehicles abroad. The steering principle of the longitudinal-coupled IRW bogie is analyzed in this thesis first. Then, a full vehicle dynamic model is built for different IRW bogies, the guiding performance of different bogies are investigated by numerical simulation. And then the dynamic performance of longitudinal-coupled IRW bogie with different longitudinal rigidity of the longitudinally arranged traction unit is analyzed.Although the self-steering ability is increased by using the method of coupling the front and back IRW by the longitudinally arranged traction unit, its dynamic curving performance is still not very satisfactory due to large angle of attack. Theoretically speaking, reasonable active steering control is an efficient way to ensure the steering capability. The theory of this method is introduced and through the careful study on the dynamic performance of longitudinal-coupled IRW bogie with or without wheel speed difference control, the feasibility study of active approach based on the feedback of wheel rotating speed is analyzed by numerical simulation.