Research On The Dynamics For LIM Vehicle With Independtant Wheel

Urban transit is a powerful tool for solving traffic difficulty, and now it has become an efficient , convenient and green transportation system. AS an important part of urban rail transit system ,Vehicle driven by linear induction motor(LIM vehicle) has been developed since the first train —set was born in 1985.Its superiority was realized and the transit style was spread rapidly. It was popular for its less transverse section, convenient maintenance, sharp curve passing, steep grade passing, free route chosen, cheaper cost and none influence by weather. Two vehicle styles was formed : one is Japan style and the other is Canada style, LIM vehicle is much different from traditional vehicle driven by rotational motor. It is driven not by the adhesion force from the contact between wheel and rail, but by the electromagnetic force from reaction plate which is mounted in track. LIM vehicle model using independent wheel was put forth in the paper and the suspension system of the vehicle was designed . application of independent wheel will bring two problems. One is if the vehicle can center automatically after wheel has a lateral displacement. The other is bad curve passing performance for no steering force. Changing the wheel profile and low friction coefficient between wheel and rail are effective methods to solve the first problem. Adopting force steering mechanism is a powerful means to solve the second problem.The paper begins with the character of linear induction motor and indicated that the efficiency of LIM is depended on the reduction of air gap of motor. The fluctuation of air gap can influence the characters of LIM. So the LIM suspension style is the important part of application of LIM vehicle. Firstly Paper gives many kinds of LIM suspension systems used overseas now and their bogies suspension system. After that the dynamic Vehicle model with independent wheel was established using Simpack software and detailed original parameters were given. Then the dynamic simulation calculation was performed and optimized parameters were chosen. On the base of optimized model, force steering mechanism was added and dynamic calculation was performed again.The conclusion shows the new model can solve the problems in the application of independent wheel. It not only can lower the air-gap of LIM, but also can solve the conflict between stability and curve passing performance when the stiffness of primary suspension was changed. By the means of using new profile with a big discrepancy of contact angle and low friction coefficient of wheel-rail contact, the weight recover force can be made fully use of to center the vehicle in the track. Theforce steering mechanism can avoid that wheel flange contacts with rail by decrease the attack angle. And, the left wheel and right wheel can rotate with different speed, the whole creeping force come down and the wear^ noise in curve can be reduced greatly. To sum up, the model with LIM> independent wheel and force steering mechanism has much more superiority than traditional urban transit Vehicle.