A Study on Hypoid Gears NVH Robustness

Hypoid gears transmission error (TE) is a metric that is usually used to evaluate their NVH performance in component level. The test is usually done at nominal position as well as out of positions where the pinion and gear are moved along their own axis and also along offset direction to evaluate sensitivity of the measured TE to positional errors. Such practice is crucial in practical applications where the gear sets are inevitably exposed to off position conditions due to a) housing machining and building errors, b) deflections of housing, bearings, etc. under load and c) thermal expansions or contractions of housing due to ambient temperature variations. From initial design to development stage, efforts should be made to design the gear sets to be robust enough to all combinations of misalignments emanated from all three mentioned categories. This study is one such effort a) to evaluate main parameters affecting TE response of a hypoid gear set at various misalignment conditions and temperature variations under various loads as well as b) quantifying topography effects on TE response under such load and misalignment conditions. Approximating surface corrections/modifications from nominal through a bi-cubical polynomial, the effects of different topography errors on loaded TE (LTE) is evaluated. Looking at overall LTE response under various micro-geometric modifications one can see how significant micro-geometry of gears are in controlling LTE behavior.Cross Reference: