Experimental investigation of gear rattle and nonlinear dynamic interaction in a dual-clutch transmission

Dual-clutch transmissions (DCT) having high efficiency and powershift are widely used in passenger cars thanks to the dual-clutch and preselection strategies. However, the dual-clutch transmission gear rattle behaviour still needs to be fully discovered, especially the influence caused by different preselection strategies. In this regard, the gear rattle sensitivity and dynamic evolution of the geartrain in a DCT were experimentally investigated on a rattle test bench and vehicle powertrain. The rattle response and instan-taneous speed of all speed gears potentially contributing to the overall rattle are measured. The measured results from the DCT were compared with a similar structure six-speed manual transmission to depict its characteristics. Moreover, a multi-degree-of-freedom nonlinear torsional model was established to gain the nonlinear dynamic response along with the rising torsional irregularities; the model considers the crucial parameters affecting rattle behaviour. Two qualitative criteria were consequently given based on the numerical results and the law of the gear motion.The experimental results on the rattle test bench show that the DCT rattle behaviour varies with dif-ferent preselected gears and is quite different from the manual transmission. The rattle sensitivity curves disclose an abrupt jump-up phenomenon when the excitation level reaches a certain level. The nominal input speed, preselection gear and lay-shaft configuration considerably determine the excitation level and amplitude increase of the jump-up on the rattle response. Based on the proposed qualitative criteria, a strongly nonlinear dynamic response is observed in the loaded gear pair under preselection conditions and deteriorates the rattle noise. A considerable dynamic interaction between active and passive sub-gearboxes is found. The appearance of the harmonics of the excitation frequency on the active input shaft that generates the high impact amplitude and density contributes to the jump-up and high vibration response on the rattle sensitivity. Finally, vehicle experiments reproduce the rattle jump-up and dynamic torsional interaction in the DCT powertrain are confirmed.(c) 2023 Elsevier Ltd. All rights reserved.