In Automated Manual Transmissions (AMTs) the clutch control strategies to manage the engagement operation and clutch vibrational behaviour are mutual interdependent and only an optimized mechatronic design could lead to an effective target from several points of view: passengers' comfort, fuel economy, system reliability, performance, driving feeling, etc. In fact, noise, vibration and harshness (NVH) phenomena are crucial subjects in the modern automotive industry. In passenger car equipped with automatic transmissions the electronic management of the coupling between engine and transmission couldn’t provide sensible improvement of comfort and overall vehicle performance during gearshifts without the availability of dependable models of the flywheel, clutch and driveline as powerful tools for vehicle design engineers. In this paper, simulations of driveline vibrational behaviour have been performed by implementing a high-order multi-body model for the dry clutch mechanism with the purpose of studying the excitation of torsional vibration caused by frictional actions during the slip phase of the clutch engagement in manual or automated manual transmissions. The analysis aims at deepen about the coupling between pressure plate wobbling and torsional motions in order to improve the current understanding of the excitation mechanisms in the frequency region of the so-called “eek noise”, 250-500 Hz. The results of this work substantiate that enhancing of torsional motion in the characteristic frequency range of the eek effect occurs in vehicle launch and gear shifting operations regardless of the rigid wobbling motion of the pressure plate. Such outcomes underline the need to include the non-linear characteristic of the clutch cushion spring in the simulation frictional induced vibration originated at clutch level. Simulations of gear-shifting operations have been carried out by applying ramp profiles to the clutch throwout bearing according to the requirements of typical manoeuvres in passenger cars.

VIBRATIONS INDUCED BY ELECTRO-ACTUATED DRY CLUTCH IN THE EEK FREQUENCY: EXCITATION IN GEAR-SHIFTING OPERATIONS

SENATORE, ADOLFO
2014

Abstract

In Automated Manual Transmissions (AMTs) the clutch control strategies to manage the engagement operation and clutch vibrational behaviour are mutual interdependent and only an optimized mechatronic design could lead to an effective target from several points of view: passengers' comfort, fuel economy, system reliability, performance, driving feeling, etc. In fact, noise, vibration and harshness (NVH) phenomena are crucial subjects in the modern automotive industry. In passenger car equipped with automatic transmissions the electronic management of the coupling between engine and transmission couldn’t provide sensible improvement of comfort and overall vehicle performance during gearshifts without the availability of dependable models of the flywheel, clutch and driveline as powerful tools for vehicle design engineers. In this paper, simulations of driveline vibrational behaviour have been performed by implementing a high-order multi-body model for the dry clutch mechanism with the purpose of studying the excitation of torsional vibration caused by frictional actions during the slip phase of the clutch engagement in manual or automated manual transmissions. The analysis aims at deepen about the coupling between pressure plate wobbling and torsional motions in order to improve the current understanding of the excitation mechanisms in the frequency region of the so-called “eek noise”, 250-500 Hz. The results of this work substantiate that enhancing of torsional motion in the characteristic frequency range of the eek effect occurs in vehicle launch and gear shifting operations regardless of the rigid wobbling motion of the pressure plate. Such outcomes underline the need to include the non-linear characteristic of the clutch cushion spring in the simulation frictional induced vibration originated at clutch level. Simulations of gear-shifting operations have been carried out by applying ramp profiles to the clutch throwout bearing according to the requirements of typical manoeuvres in passenger cars.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/4532057
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