Dynamic analysis of automotive gearing systems

The standard approach often used to reduce gear noise in automotive system is to minimize the transmission error. This is done by using stringent quality control measures in the gear manufacture, selecting desirable gear parameters, and applying profile modifications. This approach may be effective in many instances. However, there are numerous examples where the gear quality is the best that can be achieved within the manufacturing constraints, and the noise levels still exceed acceptable limits. In many cases, the system dynamics cause the gear train design to be highly sensitive to manufacturing induced transmission error. Therefore, it is advantageous to perform dynamic analysis to examine the influence of gear train dynamics and design parameters on gear noise. Proper design modifications may then be identified and applied to reduce gear noise levels. In this paper, dynamic models of typical automotive gearing applications using spur, helical, bevel, hypoid and planetary gear sets are developed analytically. Basic formulations used in modeling different types of gears are discussed in detail. These gear models are for use in finite element models of gearing systems for simulating gear whine problems. A procedure for examining the design parameters that control the dynamic mesh force generated per unit transmission error and gear case response is proposed. It can be used to understand the gear whine process and obtain ways to develop quiet gearing systems. A generic automotive transmission is analyzed to demonstrate the salient features of the proposed gear noise reduction technique.