NVH Refinement on the Agriculture Tractor using Coupled Test and Simulation Approach

The Indian farmers choice of agriculture tractor brand is driven by the ease of operation and fuel efficiency. However, the customer preference for operator comfort is driving many tractor OEMs for improvement in noise and vibration at the operator location. Also, the compliance to CMVR regulation for noise at operator ear location and vibration at operator touch point location are mandatory for all the tractors in India. NVH refinement development of the tractor plays a critical role in achieving the regulated noise level and improved tactile vibration In presented work, the airborne sources such as exhaust tail pipe, intake snorkel and cooling fan are quantified by at tractor level through elimination method. The detailed engine level testing in engine noise test cell (hemi anechoic chamber) is carried out to estimate the contribution of engine components to overall noise. The outcome of Noise source identification (NSI) has revealed silencer, timing gear cover and oil sump to be highest ranked sources in descending order. The silencer design using FEM/BEM tools is carried out which had yielded noise reduction up to 4 dB at Full load. Also, operational deflection shape of complete chassis system is carried out to identify the structural weakness. Improvement in engine primary balancing and structural changes has yielded up to 60% reduction in operator touch point vibration.