As the heavy-duty combustion engine development goes towards lower rotational speeds and higher cylinder pressures, the torsional vibrations increase. There is therefore a need to identify and study new types of vibration absorbers that can reduce the level of torsional vibrations transmitted from the engine to the gearbox. In this work, the concept of a dual-mass flywheel combined with a tuned vibration absorber is analysed. The tuned vibration absorber efficiently reduces the vibration amplitudes for engine load frequencies near the tuning frequency, but it also introduces an additional resonance into the system. By placing the tuned vibration absorber on an intermediate flange between the two dual-mass flywheels, the introduced resonance frequency will be lower than the tuning frequency and a resonance in operating engine speed range can be avoided. Numerical simulations are used to show how the torsional vibration amplitudes in a heavy-duty truck powertrain are affected by the tuned vibration absorber and how the different parameters of the tuned vibration absorber and the dual-mass flywheel affect the torsional vibrations and the resonance frequencies.

The current development of more efficient combustion engines leads to an increase in engine torsional vibrations; therefore, new technology is needed for reducing the vibrations transmitted from the engine to the driveline. In this article, the concept of power split vibration absorber is evaluated. A mathematical model of the power split vibration absorber is presented, and an analytical study shows how different design parameters affect the power split vibration absorber performance. Numerical simulations with models representing typical heavy-duty truck powertrains are used in the evaluations. It is concluded that for a low level of damping, the power split vibration absorber can provide significantly lower vibration amplitudes than a corresponding dual mass flywheel within a limited speed range. If the power split vibration absorber is optimised for the critical low engine speeds, an overall decrease in the level of vibration can be obtained, but a larger installation space than with a conventional dual mass flywheel would probably be required.

No abstract