Influence of Different Gear Flank Deviation Tolerance Classes on the Contact Pattern

Abstract

Mobility electrification advent has affected the vehicle systems’ design requirements, especially for the powertrain components. Αmong the critical fields affecting the functional performance of future powertrain components is their geometrical accuracy. For gears, the necessity of tighter manufacturing tolerances is related to the much higher rotational speeds involved in the electric motor operation than the internal combustion engine. Although the gear flank tolerance classification establishes the limits of tolerable deviations, there is no treatment regarding how different deviation factors can differently influence the dynamic behavior of gears. Therefore, when standards suggest that high-speed gears require improved tolerance classes, all deviation factors are considered a group. In the case of mobility industries like the automotive, tightening tolerance classes represent a challenge. So, the objective of the present study was the assessment of the influence of different gear deviation factors in tooth contact patterns to identify possible different effects among them. So, tooth contact analyses were performed by computational simulations for a gear sample. The influence of manufacturing profile and helix slope deviations of different tolerance classes in the contact pattern was investigated. The results have demonstrated that a class modification in helix slope deviation has a higher impact on the maximum contact pressure than a class modification in profile slope deviation. When assembly deviations are also considered, the distinct influences are intensified. Identifying the most influential deviation parameters allows the gear manufacturing sector not to have to tighter all tolerances to guarantee an adequate e-mobility gear operation.