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Simulation of Gear Shift Force Curve and Shift Rail Ramp Profile
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 12, 2010 by SAE International in United States
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This paper presents a simulation for the gear shift process of a manual transmission, implemented using a library function. All the subsystem (i.e. synchronizer and the shift system) are correlated to generate a gear shift curve for optimum shift ability prediction of a manual transmission.
A 5-speed manual transmission is used as an example in the paper to illustrate the simulation, co-relation and the validation of the gear shift performance curve on the vehicle. The dynamic behavior of the shift system and synchronizer in engaging and disengaging the gear is simulated through the gear shift characteristics to generate the shift rail's ramp profile. The synchronizer travel is co-related with the shift rail ramp profile to get a negative force after synchronization is over. The profile indicates the role of the detent ball diameter, radius on the shift rail ramp's profile etc and how it affects synchronizer force over the shift rail travel. It compares the constant slope and variable slope in the shift rail profile through differential equation to evolve the impact on shift feel. It tries to solve the issue of the gear jump out and double bump (2 nd load peak) as it plots the disengagement force with the movement of the detent ball on the ramp profile in co-relation with the synchronization travel. The simulation data on gear shift system such as shift rail's ramp profile, engagement force and detent preload, are quantitatively analyzed for the assessment of shift quality. Shift control variables are adjusted interactively to calibrate the shift system for the best trade off between shift effort and positive shift feel.
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