Application of nonlinear vibration absorbers to the control of piston secondary motion in internal combustion engines

The impulsive behavior of piston plays a key role in the Noise, Vibration and Harshness (NVH) of internal combustion engines. There have been several studies on the identification and quantification of piston impacting action under various operation conditions. In the current study, the dynamics of piston secondary motion are briefly explored, since this is fundamental to understanding the aggressive oscillations, energy loss and noise generation. Concepts of controlling piston secondary motion (and thus, impacts) are investigated and a new passive control approach is presented based on the nonlinear energy absorption of the highly transient oscillations. The effectiveness of this new method on the improvement of piston impact behavior is discussed, using a preliminary optimization exercise (with respect to engine excitation/speed, damping and stiffness of the nonlinear oscillator) that leads to the conceptual design of a nonlinear energy absorber.