| As the ideal transmission of automobile, Continuously Variable Transmission(referred to as CVT) can acquire the continuously output power so that it can achieve a good match between the vehicle driving resistance and the output torque of the engine within the range of transmission ratio permitted by transmission,then the good fuel economy and dynamic performance is ultimately obtained. However,CVT can only allow the limited range of continuously transmission ratio due to the restraint of it’s own structural characteristics and working principle. As a result,it can not ensure the ideal conditions of the engine during any driving conditions of automobile. Therefore, it comes to the question on how to increase transmission ratio as much as possible in the premise of CVT’s inherent advantages,obtaining the ideal conditions of the engine during the most driving conditions of automobile.The question represents the direction of transmission’s development.Compared with CVT, Infinitely Variable Transmission(referred to as IVT)not only has the same transmission characteristics with CVT,but also achieves the substantial expansion of the range for transmission ratio. Consequently the depth research on IVT has a more profound theoretical significance and application value.The current domestic and foreign research for IVT is mainly for the comprehensive design on the structure of toroidal traction IVT.This issue integrates the basis of the transmission characteristics on the structure of toroidal traction IVT,using theory of Tribology,Theoretical Mechanics, Mechanical Design,Materials science and other relevant basic theories to design a new type of Friction Hmisphere-Type Traction IVT System,which has the essential difference with the traditional Toroidal Traction IVT. This issue focuses on the new transmission system as the research object, expands the main research around this topic as below:1. Having the creative design and development of the Friction Hemisphere-Type Traction IVT System on the basic principle of the torque splitting.Doing the3d model design of this transmission system under UG context. Analyzing the structural features and working principle of it.In the meantime,proceeding the kinematic analysis among every component,then the transmission characteristics and governor characteristics of this transmission system is obtained. 2.Building the IVT power transmission model couplinged by IVT system and engine. Analyzing the correspondence among engine,IVT system and vehicle. Achieving the matching between the ideal conditions of vehicle and engine.Finaly the integrated control strategy is analyzed.3.Proceeding the comprehensive control research on transmission ratio adjustment for the Friction Hemisphere-Type Traction IVT System. Proposing the integrated control strategy of the transmission ratio regulation for this transmission system. Doing the parametric design of dynamical model of the transmission system.under ADAMS context.Building the corresponding state variable.Then leading the control module into Simulink,importing the corresponding control algorithm.Through the different driving conditions such as the start,urgent acceleration,steadily along and climbing,using throttle percentage as the conrtol input signal,obtaining the control result between the actual transmission ratio and target transmission ratio.4.Doing the further study on the contact pressure between the friction hemisphere pair of the transmission system. Proposing the mechanical model of clamping force between the friction hemisphere pair.Analyzing the coefficient of rolling friction through the relative motion on the surface of the friction hemisphere pair.Building the mathematical relationships among the normal pressure, the rate of change on speed ratio and engine speed. Subsequently,building the dynamical model under Simulink context,importing the relevant control algorithm,acquiring the control result of actual clamping force relative to target clamping force on the basis of the transmission control model.Consequently,the comprehensive design work for Friction Hemisphere-Type Traction IVT System is finished.5.Porposing specific Introduction and analysis for the Comprehensive performance of the transmission system,including the actual speed ratio model when considering the effect of clamping force,the travel range of the speed ratio control cylinder piston when the transmission system is equipped in automobile, the effective output power of the transmission system and the ransmission efficiency.Through the analysis of such useful comprehensive performance parameters,this paper demonstrates the rationality and the superiority of the transmission system.This paper proposes the further improvement work with regard to this transmission system at last,including the starting control of clutch,the optimization of mechanical model for clamping force and the problem with the lubrication between the friction hemisphere pair,which will be the research area in future. |
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