Experimental Investigation of Effect of Driveline Torsional Fluctuations on Overall NVH Performance of the Vehicle

Meeting various customer(s) requirements with the given automotive product portfolio within the stipulated time period is a challenge. Design of product configuration matrix is an intelligent task and it requires information about vehicle performance for different configurations which helps in deciding the level of new development. Most often the situation arises, particularly in the field of NVH, to strike the right balance between engine power and structural parameters of the body. The sensitivity of engine power on the overall NVH behavior is the key information necessary to take major business decisions. In this paper, the effect of change in torsional fluctuation of the engine on the NVH behavior of the rear wheel drive vehicle is experimentally studied. The torsional fluctuation of the driveline is given as an input with the help of an electric motor to the existing test vehicle at its differential end and the current NVH levels are measured. A test rig is built to change the levels of torsional vibration input to the vehicle. The threshold level of torsional fluctuation for the given vehicle structure is obtained by taking into account the target values of tactile vibration and subjective perception.

The results are very useful in deciding the acceptable level of change in engine power without carrying any structural change. Also, for a given power, the set of structural changes necessary in the body and suspension linkages to meet the NVH criteria can be studied. The procedure is also extended to an all-wheel drive vehicle with the help of a two wheel drive chassis dynamometer. Obtaining subjective perception of the vehicle NVH even before making the vehicle of target configuration is an inherent advantage of the proposed technique. A good correlation is achieved with the objective results and subjective perception.