Browse Publications Technical Papers 2001-01-1507
2001-04-30

Estimation of Statistical Distribution of Composite Manufactured Transmission Error, A Precursor to Gear Whine, for A Helical Planetary Gear System 2001-01-1507

Gear whine is one of the NVH attributes that have become noticeable as performance of other NVH attributes is improved. The predominant root cause of gear whine is transmission error, defined as the deviation of angular position of driven gear/s from the ideal conjugate position/s. Presence of Transmission error can be attributed to three major sources: 1) dimensional variability of individual gears during manufacturing, 2) misalignment during assembly and 3) dynamic tooth deflections during operation.
This paper describes a method to estimate statistical distribution of Composite Manufactured Transmission Error (cMTE) for a planetary gear system based on measured surface variation of the gear tooth profiles. The statistical distribution of the surface variation is derived from measured left and right profiles for four equally spaced teeth per gear in both lead and involute directions. Along the lead direction average and maximum lead offset between two gage lines is measured along with any crown. For involute direction, the roll angle at the high point is measured as well as the tip and form fall-off.
Most of the prior research in MTE estimation is concerned with single mesh point and often ignores the statistical nature of the problem. The cMTE estimation method described in this paper considers multiple mesh points and determines a single composite measure for the whole system. Also, a normal statistical distribution for each individual gear tooth profile is considered. The cMTE estimation is a two-step process. Initially measured data for gears is used to determine the statistical representation of a family of surfaces. Finally, gear meshing is simulated incrementally and the cMTE is computed at each increment. The distribution of the cMTE is then reported as a function of angular rotation from engagement to disengagement of a single tooth.

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