Isolation of Engine Vibrations from 3 Cylinder Engines on Off-Highway Machines

The BS4 regulation for emission required several changes on engines as well as design and development of new auxiliary systems. These changes affected the engine dynamic behavior and ultimately noise and vibration in engine. These changes are validated for various operating conditions on engine test cell in a controlled environment where engine is mounted on test cell with dyno. Further, this engine is used in various equipment application and needs to be validated for noise and vibration performance. Three-cylinder engines have inherent imbalance forces, hence it is extremely critical to select the proper engine isolators to reduce the vibrations and noise. This paper covers the methods used for verification of engine isolation performance. NVH tests are conducted for integration of three-cylinder engine with roadbuilding machine. An analytical model is developed to identify rigid body modes and mount transmissibility. Results from this analytical model were verified with a physical experimental modal analysis. Vibration transmissibility at each mount is measured to ensure sufficient vibration attenuation. Vibration levels on machine frame and cab seat are evaluated in various operating conditions. These evaluations helped to select suitable isolators for machine NVH performance.