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TRANSMISSION MODELS

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The take-off manoeuvre of a vehicle was studied in Section 23.9 using a simple model where the inertia of both engine and vehicle were modelled as two flywheels connected to each other by a rigid shaft and a friction clutch. This model can be made more realistic by adding the torsional compliance of the shaft, of the joints and possibly the gear wheels, as well as the rotational inertia of the various elements of the driveline. A model of the whole driveline is thus obtained, with the engine and vehicle modelled as two flywheels located at its ends. However, the. | 30 TRANSMISSION MODELS The take-off manoeuvre of a vehicle was studied in Section 23.9 using a simple model where the inertia of both engine and vehicle were modelled as two flywheels connected to each other by a rigid shaft and a friction clutch. This model can be made more realistic by adding the torsional compliance of the shaft of the joints and possibly the gear wheels as well as the rotational inertia of the various elements of the driveline. A model of the whole driveline is thus obtained with the engine and vehicle modelled as two flywheels located at its ends. However the engine shaft is itself a compliant system. Moreover its pistonconnecting rod-crank systems should be modelled as systems with variable inertia in time. At the other end of the driveline the dynamics of the transmission and the longitudinal dynamics of the vehicle are coupled by the tires which are themselves compliant in torsion. The longitudinal compliance of the suspensions may affect the dynamics of the driveline and couples with the dynamics of the vehicle which is in turn coupled with comfort dynamics. Because many of the parts that may be included in the model of the driveline have a strongly nonlinear behavior the model must include nonlinearities that prevent frequency domain solutions from being obtained if a high degree of detail is to be considered. In this case only time domain solutions can be obtained. The mathematical models of the various parts of the transmission from the engine to the vehicle will be described in this chapter. G. Genta L. Morello The Automotive Chassis Volume 2 System Design Mechanical Engineering Series Springer Science Business Media B.V. 2009 577 578 30. TRANSMISSION MODELS 30.1 COUPLING BETWEEN COMFORT AND DRIVELINE VIBRATION As predictable in a system with many degrees of freedom the driveline has many vibration modes and natural frequencies. The effects of the various modes are different and a variety of models may be used for their study. The most