Counter torque control of torsional vibration suppression device using permanent magnets

A periodic reversal spring (PRS) with permanent magnets is proposed to suppress the torsional vibration of automobile powertrains. Results of numerical dynamic simulations pertaining to automobile powertrains from a previous study show that the magnetic counter torque of a PRS reduces the torsional vibration caused by the internal combustion engine. However, the effectiveness of the PRS has only been verified at one engine operating point. Because the magnetic field of permanent magnets on a PRS is fixed, the waveform of the counter torque of the PRS is uniquely determined. Therefore, a certain mechanism is required to control the amplitude and phase of the counter torque in a PRS to suppress torsional vibrations at several operating points of an engine. In this study, we use a pair of PRSs to control the counter torque and evaluate its effectiveness based on numerical simulations and experiments. First, we show that the amplitudes and phases of the counter torque can be controlled by adjusting the phases of the PRS pair. Next, we perform a three-dimensional electromagnetic field analysis and confirm that the amplitudes and phases of the counter torques are controllable when the phases of the PRS pair are adjusted. Subsequently, we simulate torsional vibrations in powertrains using a dual-mass flywheel (DMF) damper and a DMF damper combined with a controllable PRS as torsional vibration suppression devices. The numerical simulation results show that a controllable PRS can reduce a higher amount of torsional vibration in powertrains at several operating points of an engine compared with a DMF damper. Finally, we construct a prototype of a controllable PRS that uses a simple mechanism to adjust the phases. Experimental results show that a controllable PRS can suppress torsional vibrations in the experimental system at several operating points, wherein the rotational speed and excitation torque are different.