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Development and Application of an Objective Metric for Transient Engine Clatter Noise

FCA US LLC-Anil Charan
InDepth Engineering Solutions-Aniket Parbat
Published 2019-06-05 by SAE International in United States
Several powertrain noise phenomena have been studied over the years. Sound quality metrics, like loudness, sharpness, modulation, and tonality, among others, have been developed to characterize powertrain noises. While these readily available metrics work well on steady state and some transient noises, they do not correlate directly with subjective impressions. Moreover, it is difficult to assign a meaningful single rating for time varying noises that may also be associated with simultaneous variations in frequency content. This paper summarizes the process of creating a vehicle level objective metric and its application to blind noise samples to verify correlation with subjective impressions, particularly in association with clatter noise at moderate engine speeds (2000-3500 rpm) with light to moderate throttle tip-ins. The main results include a single number rating and a rating curve as a function of engine speed useful for comparative NVH assessments of multiple vehicles or of multiple hardware iterations on a development vehicle with objectionable clatter content. The latter application is particularly useful since it gives correct feedback to an uninitiated engineer about the hardware…
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Target Setting Process for Hybrid Electric Drives Using TPA, Jury Study, and Torque Management

FCA US LLC-Vinod Singh, Anil Charan
InDepth Engineering Solutions-Aniket Parbat
Published 2019-06-05 by SAE International in United States
The idea of improved efficiency without compromising the “fun to drive” aspect has renewed the auto industry’s interest toward electrification and hybridization. Electric drives gain from having multiple gear ratios which can use advantageous operating set points thus increasing range. Furthermore, they benefit significantly from frequent decelerations and stopping as is experienced in city driving conditions. To recuperate as much energy as possible, deceleration is done at high torque. This presents an interesting but serious sound quality issue in the form of highly tonal whine harmonics of rapidly changing gears that do not track with vehicle speed thus being objectionable to the vehicle occupants. This paper presents an NVH target setting process for a hybrid electric transmission being integrated into two existing vehicles, one belonging to the premium segment and another aimed at enthusiasts with off-road applications. The demand for power has shifted from mechanical domain into electrical domain, and as such, the solution to electric drive NVH issues also lay partly, in the way these drive systems are calibrated. A time-domain Transfer Path Analysis…
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Powertrain Level Target Setting for Impulsive Noise based on Interior Noise Levels

FEV North America Inc.-Aniket Parbat, Todd Tousignant, Kiran Govindswamy
Published 2015-06-15 by SAE International in United States
The definition of vehicle and powertrain level NVH targets is one of the first tasks toward establishing where a vehicle's NVH behavior will reside with respect to the current or future state of industry. Realization of vehicle level NVH targets relies on a combination of competitive powertrain (source) and vehicle (path) NVH performance. Assessment of vehicle NVH sensitivity is well understood, and can be accomplished through determination of customer interface NVH response to measured excitations at the source input locations. However, development of appropriate powertrain source targets can be more difficult, particularly related to sound quality. This paper discusses various approaches for definition of powertrain targets for sound quality, with a specific focus on impulsive noise.
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