Abstract
The use of Continuously Variable Transmissions (CVT) in automotive applications has seen a remarkably strong growth worldwide. Customers appreciate the excellent fuel efficiency and high level of comfort of CVT equipped drivelines. Besides smooth shifting, the high level of comfort is driven by the excellent NVH behaviour of the pushbelt. In order to be prepared for increasing requirements in noise behaviour, a study was performed to optimize the noise performance of the Pushbelt CVT. In this study the dynamic behaviour of the system is simulated by Finite Element Analysis (FEA) and validated by Experimental Modal Analysis (EMA). The resulting mode shapes are related to the noise radiation by means of Planar Near-field Acoustical Holography (PNAH). This measurement method enables the determination of acoustic quantities such as the pressure, particle velocity, and intensity by using the acoustic pressure measurements in the near field of the pulleys and pushbelt as an input. The results of this study are used to improve the noise performance of the pushbelt by optimizing the pushbelt element sequence of thicker and thinner elements.
KEYWORDS – NVH, Near-field Acoustical Holography, Pushbelt, CVT, Transmission