Multi-body dynamic analysis and torsional vibration suppression in hybrid electric vehicle drivetrains using an inner damper enhanced dual-mass flywheel

Hybrid electric vehicles often experience significant powertrain torsional vibration due to diverse driving modes and frequent mode switching, which negatively impacts vehicle comfort and durability. This study addresses the multi-condition torsional vibration problem in hybrid electric vehicle powertrains by proposing and evaluating a novel dual-mass flywheel with an inner damper featuring multi-stage stiffness. We first detail the structure and operational principles of the dual-mass flywheel with an inner damper. Subsequently, a four-stage stiffness dual-mass flywheel with an inner damper is designed through theoretical calculations, and its accuracy is rigorously verified via both experimental testing and simulation. To assess its performance, a comprehensive multi-body dynamic simulation model of a hybrid electric vehicle powertrain is developed. This model is used to compare the damping efficacy of the dual-mass flywheel with an inner damper against a conventional dual-mass flywheel across various critical operating conditions, including acceleration, engine-start-while-driving, cruise-control, tip-in, and tip-out. The damping performance is quantified using key vibration indices such as speed fluctuation, root mean square, vibration dose value, peak-to-peak value, and vibration isolation rate. Simulation results show that the integration of the inner damper significantly suppresses torsional vibration across all tested conditions, leading to an average reduction of 30% in vibration indices and a 10% improvement in overall damping performance. This research confirms the effectiveness of the dual-mass flywheel with an inner damper in mitigating hybrid electric vehicle powertrain torsional vibrations under diverse operating scenarios.