Mitigation of Engine Sub-system Noise in Two Wheeler Using Crank Angle Domain Analysis

One of the main objective of manufacturer is to achieve high productivity with low cost while increasing the customer satisfaction. With increased competition in the automotive sector the product quality is defined not only from fuel economy and durability perspective but also Noise, Vibration and Harshness (NVH), which plays a vital role in attracting the customers. In two wheeler, engine is dominant noise source and its quality improvement is utmost priority. Now a days, several signal processing and sensing techniques are developed for noise source identification of an engine but precise source identification can be achieved only by advanced analysis technique. This paper focuses on a procedure for noise source identification from engine sub-system viz. valve operation and its generation mechanism using crank angle domain analysis in two wheeler engine. Baseline noise measurements were carried out for critical frequency identification. Further, vibro-acoustic measurements were carried out on engine and data analysis was done in angle domain using reference of crank angular position. Source identification was done by correlating the vibro-acoustic data with the operation of engine valves and related components. Based on source identification, engineering solutions were proposed and evaluated for its vibro-acoustic behavior. Results indicated significant reduction in contribution of impulsive noise to overall noise of the engine. Using this procedure, one can clearly link the abnormal noise phenomenon from valve mechanism to its sub-components which will help in selecting feasible engineering solution and mitigating the sub-system noise.