NVH Analysis and Optimization of Engine Balance Shaft Module 2021-01-1032
For any combustion engine, balance has always been important regardless of types of cylinder layout. One of the disadvantages of the inline four engines is the second-order unbalanced forces, which leads to high-frequency excitation of vehicle’s structure and consequent internal noise. Balance shaft modules (BSM) are often used in inline-four engines, to reduce the second-order vibration and mitigate engine imbalance.
Balance shafts are often running at light load and high-speed condition which could induce both gear rattle and gear whine from the BSM gear set. Typically, scissor gear set is used between crankshaft and BSM to reduce the gear rattle noise. However, a poor scissor gear design could easily lead to unpleasant gear whine noise.
There is an increasing trend to shorten development cycles and reduce cost using simulation models. This paper discusses an analytical method to simulate gear whine and rattle generated by engine BSM. Simulation software MASTA is a robust and fast tool to perform such analysis. Gear design sensitivity analyses including gear macro and microgeometry was conducted. Finally, reasonable correlation was achieved between the simulation and dyno test data.