13 Automotive Applications of Active Vibration Control 1

In recent years, commercial demand for comfortable and quiet vehicles has encouraged the industrial development of methods to accommodate a balance of performance, efficiency, and comfort levels in new automotive year models. Particularly, the noise, vibration and harshness characteristics of cars and trucks are becoming increasingly important (see, e.g., (Buchholz, 2000), (Capitani et al., 2000), (Debeaux et al., 2000), (Haverkamp, 2000), (Käsler, 2000), (Wolf & Portal, 2000), (Sano et al., 2002), (Mackay & Kenchington, 2004), (Elliott, 2008)). Research and development activities at ContiTech and the UniBwM have focused on the transmission of engine-induced vibrations through engine and powertrain mounts into the chassis (Shoureshi et al., 1997), (Karkosch et al., 1999), (Bohn et al., 2000), (Svaricek et al., 2001), (Bohn et al., 2003), (Kowalczyk et al., 2004), (Bohn et al., 2004), (Kowalczyk & Svaricek, 2005) (Kowalczyk et al., 2006), (Karkosch & Marienfeld, 2010). Engine and powertrain mounts are usually designed according to criteria that incorporate trade-offs between vibration isolation and engine movement since the mounting system in an automotive vehicle has to fulfil the following demands: • holding the static engine load, • limiting engine movement due to powertrain forces and road excitations, and • isolating the engine/transmission unit from the chassis. Rubber and hydro mounts are the standard tool to isolate the engine and the transmission from the chassis. Rubber isolators work well (in terms of isolation) when the rubber exhibits low stiffness and little internal damping. Little damping, however, leads to a large resonance peak which can manifest itself in excessive engine movements when this resonance is excited (front end shake). These movements must be avoided in the tight engine compartments of today’s cars. A low stiffness, while also giving good isolation, leads