Characterisation of torque converter dampers: A novel method for exciting dampers through torque pulsation generation

As part of a wider study into torque converter damper characterization, a new method to replicate representative torque fluctuations required to excite the damper has been developed. The dynamometers currently utilised within the University of Bath’s transmission research facility are not capable of the dynamic response necessary to excite the damper in a way that mimics the excitation that occurs in vehicle; the objective of this research was to produce a mechanical solution through the use of an adapted motored engine. A motored diesel engine has been adapted to act as a set of air springs through the deactivation of the cylinder valves and by controlling the air pressure in the cylinders using a compressed air supply fed into the engine via the modified injectors. The engine crankshaft is then powered using the dynamometers installed on the rig; thus the electric machines can provide a ‘mean’ torque which is then supplemented by the torque pulsations produced by the cylinder air springs. The crankshaft output is then connected to the torque converter, exciting the damper and allowing the full range of damper performance to be analysed. Proof-of-concept testing results have been compared to fired engine data and an initial Simulink model and have shown that the concept is capable of producing torque fluctuations with magnitudes that are very similar to a fired engine; the pulsation generator is actually capable of producing a much wider range of torque pulsations then a fired engine, which will allow a much larger range of characterisation tests to be performed then if a fired engine was used to excite the damper.