New Pass-by Noise Regulatory Norms IS 3028:2023 (Part 2) - an Analysis of Acceleration and Noise Source Contribution 2024-26-0199

Worldwide automotive sector regulatory norms have changed and become more stringent and complex to control environmental noise and air pollution. To continue this trend, the Indian Ministry of Road Transport is going to impose new vehicle exterior pass-by noise regulatory norms IS 3028:2023 (Part2) to control urban area noise pollution. This paper studies the synthesis of M1 category vehicle driving acceleration, dominant noise source, and frequency contribution in exterior PBN level. A vehicle acceleration analysis study was carried out to achieve an optimized pass by noise (PBN) level based on the vehicle’s PMR ratio, reference, and measured test acceleration data. Based on the analysis, test gear strategy was decided to achieve a lower PBN level. This strategy involved increasing the effective final drive ratio and optimizing engine calibration, resulting in improvement with acceleration in the i^th gear. This increased acceleration surpassed the upper limit of the reference acceleration range; hence, the vehicle was tested in a combination of both gear (i^th and i^th+1) conditions. With this approach, a significant noise improvement could be achieved in overall PBN level. Furthermore, an analysis of exterior pass-by noise sources was conducted during acceleration and constant speed test conditions. Using a masking technique, each major noise source contribution to the overall pass-by noise level was identified. The powertrain emerged as the primary noise source, with its mid-frequency noise making a substantial contribution to pass-by noise. A frequency analysis was also performed to address higher intake noise. These innovative approaches resulted in a considerable reduction in the overall pass-by noise level. Additionally, by implementing these strategies, OEMs could meet the new PBN regulatory standards for all their existing and upcoming vehicle models.