Study On Electromechanical Coupling Dynamics Characteristics Of Straddle Monorail Traction Gear System

Straddle monorail transportation is widely used in mountainous and coastal cities because of its advantages such as small floor area,strong adaptable terrain ability and short construction period.As the key component of straddle type monorail,traction drive system is a complex electromechanical coupling system composed of traction motor,gear transmission system and wheel axle.Its failure evolution mechanism is different from that of single component,there is electromechanical coupling effect.Its dynamic behavior characteristics directly affect the safety of the whole vehicle.But the combination of factors such as the complicated and changeable operating conditions brought by the continuous small curve radius curve in mountainous areas,the manufacturing and installation errors of gear systems,and deformation of support system under load will inevitably cause the axle to misalignment,causing the gear teeth to eccentrically contact and accelerating the failure of gear,inducing safety accidents,causing serious economic losses and adverse social impacts.Therefore,the study of electromechanical coupling dynamics characteristics of traction gear system under fault condition has important theoretical significance and engineering practical value for the safe and reliable operation of straddle monorail traction system.In this paper,taking the straddle monorail traction gear drive system as the research object,considering the axle deflection fault,and take the internal excitation of the gear system as a starting point to establish a multi degree of freedom bending-torsion-shaft dynamic model of the straddle monorail traction gear transmission system.Then,the traction motor is coupled with the gear drive system,the electromechanical coupling dynamics model of traction motor and gear drive system is established,and the electromechanical coupling effect of motor gear system is clarified.The main research contents are as follows:(1)Calculate the time-varying contact line length of the helical gear pair,and divide the helical gear into a series of uncoupled spur gear slices based on the slice method.Base on the potential energy method to obtain the meshing stiffness of the spur gear slice at each moment to calculate the time-varying meshing stiffness of the helical gear.Then the control variable method is used to explain the influence of helical gear design parameters on the time-varying meshing stiffness is explained.(2)A parallel axis gear axis error model including center distance error,meshing plane error,and perpendicular to the meshing plane error is established.A method for calculating the time-varying meshing stiffness of helical gears under axial deflection is proposed.It provides excitation data parameters for the subsequent research on the dynamic vibration characteristics of gears under the fault condition of axis misalignment error.(3)Comprehensively consider factors such as support stiffness and damping of bears,meshing stiffness and damping of each gear pair,torsional stiffness and damping of shaft and other parameters to establish a straddle monorail two-level transmission gear system 13-degree-of-freedom bending-torsion-axis coupling concentrated mass dynamics model.The dynamic vibration characteristics of the system under normal and axle deflection conditions were solved by Runge-Kutta method with 4-order variable step size.(4)Based on the coordinate transformation,the dynamic mathematical model of traction motor in d-q coordinate system.Taking the electromagnetic torque as the intermediate variable to couple the monorail gear system with the traction motor,and establish a dynamic model of the electromechanical coupling of the traction motor-gear system.Elucidate the evolution law of electromechanical coupling dynamics.