Research on gearshift of Non-synchronizer automatic mechanical transmission based on hierarchical bounding box collision detection algorithm

Replacing synchronizers with dog clutches in automated mechanical transmission leads to reduction in development costs and greater compactness. The key to achieving shock-free gear-shift control and minimizing power interruptions in NSAMT lies in accurate modeling of dynamic gear-meshing collisions and high-quality analysis of gear-shifting factors. The present work contributes solutions to address the above-mentioned two challenges/ limitations during the NSAMT shift process: 1) hierarchical bounding box collision detection algorithm is proposed for accurately calculating collision forces; 2) The simulation and analysis consider various influencing factors, including the initial collision position between the sleeve and gear ring during shifting, engagement speed difference, and shift force. The simulation results show: that the initial impact position does not affect the initial impact force but can alter the engagement time. Moreover, under identical shift forces, collisions between meshing teeth sides generate greater collision forces compared to tip-to-tip collisions. Additionally, it is observed that there is no linear relationship between tooth side collision force and shift force magnitude; thus, a higher shift force does not necessarily result in a greater impact force throughout the entire shifting process.