IC (Internal Combustion) engines are evolved and refined over time to greater levels of technology in terms of emission, performance, NVH (Noise, Vibration & Harshness), and design philosophy. Crank-train generates a greater impact on NVH optimization due to its geometry and dynamics. Hence, more attention to mass balancing is required to minimize the negative impact on NVH.
The present work demonstrates the evaluation of balancing rate of crank-train system from the first principle of couple balancing. Calculations are conducted at the concept stage to estimate an internal rotating couple balancing of crank-train system due to counterweights and rotating masses. As crankshaft weighs approximately 10-12% weight of an engine and its counter weight plays a vital role in balancing, its optimization will result in a significant impact on NVH. Therefore, based on balancing rate, engines’ crankshaft was optimized and to validate the methodologies, forces on engine mount and main bearings were evaluated for both the base and optimized engine.
Conventionally, CAE analysis needs to be conducted at each iteration of optimization to evaluate the balancing of the system. However, using the mentioned approach, estimating balancing at a preliminary stage of design optimization proves to be effective in time-saving too. Forces on the crankcase and engine mounting arm evaluated as these are exciting forces for in cab NVH.