Analysis of a Dual Mass Flywheel System for Engine Control Applications

Dual Mass Flywheel (DMF) systems are today widely adopted in compression ignition automotive powertrains, due to the well-known positive effects on vehicle drivability and fuel consumption. This work deals with the analysis of undesirable effects that the installation of a DMF may cause to engine and transmission dynamics, with the objective of understanding the causes and of determining possible solutions to be adopted. The main results of an experimental and simulation analysis, focused on the rotational dynamics of a powertrain equipped with a DMF system, are presented in the paper. A mathematical model of the physical system has been developed, validated, and used to investigate, in a simulation environment, the anomalous behavior of the powertrain that had been experimentally observed under specific conditions. Particular attention has been devoted to two aspects that are considered critical: engine cranking phase; interactions between powertrain dynamics and idle speed control. Experimental tests have initially been carried out in a laboratory environment, to characterize the performance (both static and dynamic) of the DMF system under study. On-board tests have subsequently been performed on a vehicle whose powertrain is equipped with the same DMF. During on-board tests, signals preprocessed by the Electronic Control Unit have been recorded together with analog signals sampled at higher frequency with an external device.