Reduced ride comfort caused by beating idle vibrations in passenger vehicles

- This study examines how beating idle vibrations lead to reduced ride comfort in passenger vehicles.
- Beating vibrations were found to induce greater discomfort than single-frequency vibrations.
- The level of discomfort varied with beating frequency and amplitude ratio.
- The frequency dependency of beating vibrations was compared with the ISO frequency weighting function.

Idle vibrations that occur in passenger vehicles at a stop cause passengers to feel discomfort, thus leading to reduced ride comfort. Beating vibration takes place when the frequency of engine vibrations is similar to the frequency of vibrations due to auxiliary parts in the engine room, and this produces a rapid deterioration in ride comfort. This study analyzed beating idle vibrations in an actual vehicle, and performed experiments to assess changes in ride comfort in relation to the amplitude ratio of two vibrations having similar frequencies and their beating frequency. At most frequencies, ride comfort was poorer when the beating vibrations had higher amplitude ratios. A higher level of discomfort was found when the beating frequency fell in a range of 1-4 Hz. Beating vibrations with an amplitude ratio of 0.8 and a beating frequency of 1.0 and 2.0 Hz caused greater discomfort by 3.8 dB compared to single-frequency sinusoidal vibrations.