Analysis of vibrational comfort in a car equipped with a modified 3-cylinders engine

Regular paper

Alix Carbajo

PSA Peugeot CitroŽn

Wednesday 3 june, 2015, 11:40 - 12:00

0.7 Lisbon (47)

Abstract:
In order to improve engines in a way that reduces emissions and consumption of future cars, automobile manufacturers are developing innovative drivetrains like new 3-cylinders engines. In spite of improving the consumption and emissions, these modifications imply a new vibrational and acoustical environment in the car interior which can affect the comfort of drivers and passengers. Indeed the engine presents unusual harmonics at low frequencies and drivers may consider its sounds and vibrations as unpleasant or even uncomfortable. The aim of our study is thus to analyse the vibrational comfort in the particular case of a 3-cylinders engine whose harmonics are much lower in frequency and higher in magnitude than a common engine. We work on the analysis of modifications and their consequences to propose organic or digital solution to improve the vibroacoustic comfort like modification of the wheels horizontal suspension to lower the vibrationís magnitude. Another axis of improvement is a sonification solution that enhances the engine sound. The study took place in a driving simulator where modal parameters of a car horizontal suspension Ė amplitude and central frequency of the mode Ė can be changed and proposed to several testing subjects. This allowed us to determine the acceptability threshold and the couple of parameters which gives the best results in terms of comfort. Moreover, by testing two different sounds of the same engine, it has been showed how a better quality sound influences the evaluation of vibrational comfort.

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