Whine Noise Development of Engine Timing Gear System in Heavy Duty Vehicle

Gear train is the most applied in the heavy duty engine timing system on the benefit of reliability, durability, timing accuracy, maintenance, and high torque transmission. But the gear train is vulnerable to rattle and whine noise due to many serial gear connections, which lead to more possibility for gear backlash impact and gear transmission errors compared with chain and toothed meshed belt timing systems. Furthermore, normal heavy duty diesel vehicles like truck and bus are well vibration isolated from engine at gear noise frequency range. Therefore, noise source control is inevitable in the developing process in heavy duty diesel vehicles. The objective of this paper is to reduce timing gear whine noise in the engine developing process for heavy duty vehicles. Main focus is modification of gear tooth shape in the proto engine developing process considering vehicle driving modes. To investigate engine timing gear whine noise, transmission error analysis was executed in accordance with proto type gears and optimal gear tooth modification was induced by transmission error analysis, engine bench, and vehicle test.