Making diesels quiet and clear

Researchers look at the relative influence of gear design parameters on the rattle noise of a diesel engine timing gear train.

The gear train that drives the camshaft and fuel injection pump is an important set of components in diesel engines. This critical subsystem is highly loaded by periodic torque changes due to engine firing, torque on the camshaft required to lift each valve, and the fuel injection pump. This loading causes the gears to rattle and whine.

Gear rattle, which is usually the greatest source of gear noise in diesel engines, is a result of gear teeth impacting the bounding gear tooth flanks of the mating gear as the tooth clearance is transferred from one side of the tooth to the other. The impact of the gear tooth as this event occurs radiates noise and vibration. The other type of noise, whine, is the result of geometric errors in the gear’s meshing tooth position as a result of gear manufacturing variation, gear mounting error, or gear tooth and support deflection.