Clonk induced response from synchronizer engagements in dual clutch transmissions

Hong Kong Polytechnic University
Publication Type:
Conference Proceeding
Dynamics for Sustainable Engineering, 2011, pp. 1322 - 1332
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The dual clutch transmission (DCT) is capable of providing mechanical efficiencies comparable to manual transmissions with clutch-to-clutch shifting capabilities of planetary automatic transmissions. Vehicle powertrain equipped with DCTs are considered to be lightly damped dynamic systems, with damping sourced from torsional vibration absorbers and parasitic losses in clutches, transmission and differential considerably less that the damping provided by torque converters in planetary automatics. Consequently, DCTs are exposed to increased response under transient conditions, typically requiring more stringent control strategies for performing clutch-to-clutch shifts, for example. Synchronizer actuation, however, is not given the same detailed level of control to ensure minimization of observable transient response, nevertheless, the high degree of nonlinearity in the mechanismsâ actuation presents potential for initiation of undesirable transients. This paper is tasked with investigating the nonlinear engagement of synchronizers contribution to the introduction of noise, vibration, and harshness (NVH). Of particular interest is the initiation of clonk response in the powertrain, considered to be high frequency (300-5000Hz) elasto-acoustic response in powertrains, typically induced through the nonlinear response, such as synchronizer engagement, interacting with frequencies in long hollow shafts. A multi degree of freedom model of a dual clutch transmission equipped powertrain is presented using lumped inertia-stiffness elements, structured to provide the capabilities for synchronizer engagement using mean engine torque and nonlinear synchronizer models. Synchronizer engagements are undertaken for a variety of input pressures in conditions associated with clonk response. Time and frequency domain results for shaft and sleeve responses post-synchronization are used to evaluate the introduction of frequencies consistent with clonk response. The influence of gear mash nonlinearity and chamfer alignment on the synchronizer response is also studied.
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