Research On Torsional Vibrations In Shanghai Maglev Track Inspection Vehicle's Driveline

Maglev Transpid system is a fast and safe traffic system. The maglev track must be kept clean and good situation for the operations of maglev vehicle. The research objective of this dissertation is Shanghai Maglev Track Inspection Vehicle (SMT). SMT is a special engineering vehicle, which is not only a mobile platform of instruments for track inspection, also a tractor vehicle when needed. On the one hand, instruments for track inspections demand that the vibrations of SMT should be very little; on the other hand, serious torsional self-excited vibration in SMT's driveline must be avoided during towing work mode. Thus, it is necessary and important to study torsional vibrations in SMT's driveline.This dissertation firstly analyses the needed work modes of SMT. Whether the hydraulic torque converter is locked is clear during all required work modes. Torsional parameters of the drivline are calculated. Based on experimental data, dynamic torques of turbine and pump are shown as algebraic equations, and dynamic torsional damping of the hydraulic torque converter is estimated.According to front-rear symmetrical characteristics of SMT's driveline, two 7 DOFs models are used to replace SMT's driveline. A linear model describes the driveline when the hydraulic torque converter is locked, while a nonlinear model describes the driveline when the hydraulic torque converter is hydraulic coupling. Natural frequencies of the driveline are calculated, and compared with frequencies of diesel engine's torque excitements and natural frequencies of vehicle's vertical vibration system and vehicle body vibration system. As a result of the comparison, it shows that those frequencies are far away fom natural frequencies of torsional vibration system of the driveline. Vibration responses of the driveline are calculated by numerical simulations when the hydraulic torque converer is hydraulic couping. Then, it points out that torsional vibrations in the driveline are little.Suppose the tractor vehicle's velocity is a variable, a popular model of wheeled tractor vehicle's driveline is built, and the driveline is simplified as a 2-DOF-vibration system. After variables transfering, a 2-order nonlinear ordinary differential equation (ODE) is used to describe torsional self-excited vibration system of the drivline. With the qualitative analysis of the ODE, the existence of torsional self-excited vibration in...