Experimental Approach for the Knocking Noise Source Identification & Its Suppression through Lubrication Regime Optimization in Crank-Train of an IC Engine 2022-28-0067

Over the years, Fuel efficiency and cabin comfort of vehicle has become increasingly important in buying decision and can significantly give competitive edge to the vehicle in marketplace. Weight and friction reduction of rotating and reciprocating components in engines is one of the proven approaches to improve the efficiency of internal combustion engine. To reduce the friction, the general approach is to use low viscosity engine oils, improve the surface finish and reduce the contact area of sliding elements, switch over from sliding contact to rolling contact etc. However sometimes this approach has adverse impact on engine NVH characteristics due to occurrence of abnormal transient noise due to mechanical knocking of the components in specific operating conditions. The mechanical knocking noise in engine generally occurs due to interaction of engine components with inadequate lubrication regime, in-appropriate clearance, higher combustion pressures/speed or due to combination of above-mentioned phenomenon.

This paper describes an analytical approach undertaken to identify the source of mechanical knocking noise observed from piston-train in an inclined engine. The analytical approach involved experiments, Noise, vibration, In-cylinder pressure data acquisition and its analysis in angle domain to understand the physical phenomenon happening during the noise occurrence and its mechanism. After identification of the noise source and phenomenon this paper touches upon the experimental setup and methodology to identify the countermeasures for knock noise and its effectiveness.

These countermeasure solutions of lubrication regime improvement in the crank-train identified through experimentation have resulted in significant reduction in noise and vibration levels in the subject engine without any durability concern and cost impact.