| High torque hub drive system is the core component of large tonnage engineering vehicles.It carries many core functions such as driving,transmission,deceleration and braking,and has the characteristics of high integration,long service life,stability and reliability.However,with the improvement of performance requirements such as loading capacity,reliability and ride comfort of engineering vehicles,higher requirements are put forward for the structural design,dynamic performance and stability of high torque hub drive system.Taking the high torque hub drive system of 400 t mining dump truck as the research object,this paper makes a detailed study on the key dynamic performance and mutual coupling characteristics of each subsystem and the whole system through contact friction theoretical analysis,equivalent moment of inertia research and dynamic modeling analysis.At the same time,based on the dynamic response load spectrum,combined with the research of stiffness matching,modal decoupling and topology optimization,the multi-directional reliability analysis and specific structure optimization design of the system are completed,which lays a foundation for the design and optimization of this type of system.The main research contents and achievements of this paper are as follows:(1)Solve the key and difficult problems of system dynamics modeling and improve the accuracy of dynamics modeling.The fractal contact theory is proposed to study the surface contact stiffness of parts,and experiments are designed to calculate the surface contour of key parts,identify fractal parameters and calculate the contact stiffness.Based on the static friction theoretical model considering Stribeck effect and combined with the friction characteristic curve of friction lining paper-based composites,the key friction parameters in the brake are defined.Based on the energy conservation method,the equivalent vehicle load is calculated.(2)Based on the dynamic model of hub drive deceleration system and wet multi disc brake system,the output characteristics and braking performance of the system are studied,and the essential reasons affecting the running smoothness of the system are revealed.The key influencing factors of braking performance are obtained,and the theoretical torque calculation model is modified by the average compression force loss coefficient to improve the calculation accuracy.Through the whole machine load experiment,the accuracy of the system dynamics model is verified and the reliability of the model is improved.(3)Based on the overall dynamic model and motion mechanism of the system,the operation process of the system is divided into the normal working stage and braking stage of the mining dump truck.Taking the system output characteristics and braking performance as the analysis index,the coupling characteristics between the transmission deceleration system and the braking system are studied to solve the problem that the interaction between subsystems is difficult to quantify,it provides a reference for the coupling design of reducer and brake in high torque hub drive system.(4)The load spectrum of parts is obtained through system dynamics simulation.Combined with external excitation analysis,based on the research of system constraint mode,structural stiffness and fatigue life,the reliability of the system is comprehensively evaluated to solve the problem that it is difficult to accurately define the load spectrum in reliability analysis.The research on structural topology optimization aiming at modal decoupling and stiffness matching is proposed to improve the structural reliability and running smoothness of the system. |
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