Search Results

NVH refinement of passenger vehicles is crucial to customer acceptance of contemporary vehicles. This paper describes the vehicle NVH development process, with specific examples from a Diesel sedan application that was derived from gasoline engine-based vehicle architecture. Using an early prototype Diesel vehicle as a starting point, this paper examines the application of a Vehicle Interior Noise Simulation (VINS) technique in the development process. Accordingly, structureborne and airborne noise shares are analyzed in the time-domain under both steady-state and transient test conditions. The results are used to drive countermeasure development to address structureborne and airborne noise refinement. Examples are provided to highlight the refinement process for “Diesel knocking” under idle as well as transient test conditions. Specifically, the application of VINS to understanding the influence of high frequency dynamic stiffness of hydro-mounts on Diesel clatter noise is examined.

Optimization of the interface between the powerplant and vehicle frame/body is critical to obtaining superior interior structureborne noise and vibration characteristics in the vehicle. This paper demonstrates the combination of new and existing simulation/experimental methodologies for powerplant integration, including results from case studies. Multi-body simulation based methodologies are used to optimize the location, number, and type of powerplant mounts on a vehicle, taking into account the input forcing from the engine and frequency-dependent mount properties. Upon obtaining the first prototype vehicle, a procedure to evaluate the effectiveness of the powerplant mounts using a vibrational power flow technique, is described. The influence of mount bracket resonances on interior vehicle sound is shown and a new procedure to optimize mount brackets, provided.

The sound quality and performance of an automotive engine are both significantly influenced by the “air-to-air” system, i.e., the intake system, the exhaust system, and the engine gas dynamics. Only a full systems approach can result in an optimized air-to-air system, which fulfills engine performance requirements, overall sound pressure level targets for airborne vehicle noise, as well as sound quality demands. This paper describes an approach, which considers the intake system, engine, and exhaust system within one CAE model that can be utilized for engine performance calculations as well as acoustic simulations. Examples comparing simulated and measured sound are discussed. Finally, the simulated sound (e.g., at the tailpipe of the exhaust system) is combined with an interior noise simulation technique to evaluate its influence inside the vehicle's interior.

The shifter lever is one of the main customer contact points in the vehicle. Vibration levels at this contact point have an effect on perceived vehicle quality. For this reason, shifter lever vibration and the corresponding transfer paths from the transmission to the shifter lever need to be considered during vehicle development. On a recent program, experimental measurements identified the shifter cable to be a significant transfer path for shifter lever vibration. An integrated Computer Aided Engineering (CAE) and experimental effort was undertaken to model and optimize the shifter lever and cable assembly for reduced vibration. Experimental data was used to better understand the vibration phenomenon, set boundary conditions for the CAE modeling, and for correlation. The CAE model contains the shifter lever assembly and a detailed cable assembly model.