A Multibody Dynamics Approach to Assess Auto Pull Behavior of Gear Shift System

Gear shift system in a gearbox is used to shift the power flow from one gear set to another gear set which enables manual transmission to maintain different torque and speed combination. Shift quality is determined by the response of the gear shift lever while changing the gears. Shift force over the entire travel event of engagement and disengagement for multiple gear sets is the key factor influencing gear shift quality. If the shift forces are higher, the effort required for shifting will also increase resulting in uncomfortable shifting. On the other hand, with lower shifting force, sudden jerk, vibration or change in vehicle condition may also cause shifting which is undesirable and may lead to safety issue. One of the important features of shift system is auto pull behavior observed while shifting. While shifting, driver starts displacing the shift lever and after threshold point the transmission itself pulls the shift lever to the end point, reducing driver effort. In the present study multibody dynamic (MBD) approach is used to evaluate auto pull behavior of gear shift system. Detailed rigid body dynamic modelling of the gear shift system along with its subsystems, power trains is developed in the virtual environment. Different geometric and non-geometric parameters affecting the auto pull behavior of shift system are studied. The results from MBD analysis are correlated with analytical calculation and validated with experimental measurement. Virtual engineering approach helps in establishing the design parameters and their optimization through use of simulation methodology even before physical prototype is built and thus reduces the prototype building and testing cost. This study can further be utilized to automate the design process as per shift system requirement.