High-contact ratio spur gears with conformal contact and reduced sliding

The high-contact ratio (HCR) spur gear is a possible choice for a quiet and smooth gearing system. However, HCR spur gear of the involute type has several constraints, such as high sliding contact under large loads and interference problems in high speed reduction systems, so its benefits may not be fully offered. As a result, the primary goal of this research is to design a non-involute HCR spur gear with reduced sliding contact, enhanced fillet strength, better lubrication conditions, and no interference issues compared to the traditional HCR involute pair. A generalized mathematical model for defining the gear tooth profile and its geometrical aspects is built based on the path of contact shape. The involute curve length parameter and maximum pressure angle during the meshing cycle are only introduced to characterize this model. This model is utilized to create a new non-involute HCR gear pair that provides a free-form tooth profile to meet the design requirements. To demonstrate this method, certain case studies are provided, and the analytical results are validated using the finite element method. The new gear's performance is compared to the traditional involute gear that is currently in use. The results showed that by employing the proposed method, the HCR spur gear can achieve better surface durability and fillet strength.