Investigations on Valve Train Noise in Multi-Valve Engines

Due to the high amount of valve train noise in multi-valve engines measures were developed to reduce this noise. These measures are dynamically optimized profiles and cam phasing (small angular shift between neighboured cams). Both measures show a drastic reduction in valve train noise and also overall engine noise but do not have any negative effects on performance, economy and costs. Not only overall noise is improved but also sound quality especially impulsiveness characterized by the Kurtosis factor. To assess these design changes with respect to radiated noise in the early design stage an estimation method was used. The estimation method is based on the calculated force and velocity time histories and shows good correlation with the measured data.