Gearshift Comfort Optimization Research Of Sedan Manual Transmission

With the improvement of living standard, people requirement of gearshift comfort of automobile is becoming harsher. Shifting system is the core part of manual transmission for achieving shift function; its performance determines the vehicle shifting quality largely. Consider the analysis of working process and principle of shifting system. The main affecting factors of gearshift comfort are found out and the general parameter laws of gearshifting comfort system are summed up. With the help of virtual simulation test technology, the research conclusions provide theoretical support for the optimization of gearshift comfort.First, the subjective and objective evaluation systems of gearshift comfort are analysised and the comfort optimization objects apply to this paper are choosed.Second, based on selecting process and shifting process, the structure, principle and function of modern shift system are researched and mathematical theory models are established, the main parameters which influence the gearshift comfort are found out.The accurate 3D models of manual transmission system are completed by using UG NX software. The dynamic simulation model of shift system is established after the simulation parameters set in ADAMS.By using the simulation, the influence laws of structure and performance parameters of external control mechanism, inner shift mechanism and synchronizer are researched. The results indicate that, When the arrangement radius of flexible shaft is steady, the displacement efficiency and force efficiency are decreasing with the increase of friction coefficient between cable and shaft sleeve, displacement efficiency increase with cable stiffness increasing,but cable stiffness has no effect on force efficiency. The force of gear selecting depend on the matching relationship between pin spring force, gear selecting type line and weight of barrel, generally, selection force increase with the pin spring force and the cone angle increasing. Shifting force increase with the pin spring force, the shift typeline not only influence the shifting force, but also influence the gearshift comfort. The maximum gearshift force and synchronization time decrease with the increasing of friction coefficient of synchronizer cone but friction coefficient has no effect on the second impact force. Pre-synchronization slider spring force has no effect on the maximum gearshift force, but will affect the locking function of synchronizer.According to practical experiences and the research results, a general optimization method of gearshift comfort is summed up; it would provide an important reference for optimization and improve gearshift comfort.