Title: Method for Measuring and Analyzing Transient Powertrain Vibrations of Hybrid Electric Vehicles on an Acoustic Roller Test Bench
text: In terms of customer requirements, driving comfort is an important evaluation criterion. Regarding hybrid electric vehicles (HEVs), maneuver-based measurements are necessary to analyze this comfort characteristic [1]. Such measurements can be performed on acoustic roller test benches, yielding time efficient and reproducible results. Due to full hybrid vehicles’ various operation modes, new noise and vibration phenomena can occur. The Noise Vibration Harshness (NVH) performance of such vehicles can be influenced by transient powertrain vibrations e.g. by the starting and stopping of the internal combustion engine in different driving conditions. The paper at hand shows a methodical procedure to measure and analyze the NVH of HEVs in different driving conditions. In order to investigate the influence of noise and vibrations by restarting and stopping the internal combustion engine (ICE) (like switching between electric and hybrid driving or the start-stop function) on the driver, acoustic and vibration measurements are performed inside the vehicle. A binaural artificial head is used to examine the acoustic effects on the vehicle interior noise. The vibration behavior is analyzed using acceleration sensors at defined measurement positions. Regarding the human perception of the NVH performance, characteristic values, related to the vibrational response of the vehicle, are needed for a vehicle evaluation. By combining the measurement data of the transient powertrain vibrations with evaluation approaches (ISO 2631-1, DIN EN 61672-1, spectrograms using Fourier transform (FFT) and subsequent psychoacoustic criteria) a frequency-dependent vibration analysis is performed. The analysis, depending on measurements on an acoustic roller test bench, supports the development of HEVs’ NVH performance, regarding the perceived driving comfort by the customer.