Elastohydrodynamic lubrication of hypoid gear pairs at high loads

Abstract

The definitive version can be found at: century. Transmission efficiency as well noise and vibration concerns require combined elastohydrodynamic and tooth contact analysis of hypoid gear teeth pairs through mesh. Although such analyses have been reported for general cases of elliptical point contact conjunctions with angled flow entrainment, they do not comply with the prevailing load and kinematic conditions in differential gears. In particular, teeth pair contacts are subject to significant loads of order of several kN requiring solution to the EHL problem at such high loads. The current analysis reports solutions for rolling and sliding elastohydrodynamics of hypoid gear teeth pairs at realistic drive torques, not hitherto reported in literature.

Non-Newtonian mixed elastohydrodynamics of differential hypoid gears at high loads

“…This is carried out using the Calyx software [18,29]. A full description of the approach followed is given in Mohammadpour et al [21] with a brief description provided in section 2.3.…”

“…The current study uses the approach of Conry et al [42] and extends it to the case of elliptical point contact with angled lubricant entrainment into the contact, as is the case for hypoid gear teeth pairs through mesh (Mohammadpour et al [21]). Thus:…”

“…The work in [21] is extended here to include non-Newtonian shear of thin films at high loads, whilst retaining the angled lubricant entrainment flow into the rolling and sliding contact and using realistic inlet boundary conditions. Furthermore, the non-Newtonian shear behaviour variously reported for hypoid gear pairs makes use of the lubricant shear rate as a function of hyperbolic sine function of shear stress, which allows the limiting shear stress of the lubricant to be exceeded.…”

“…He considered the contact as an elliptical point contact. Similarly, Mohammadpour et al [21] also used an elliptical contact footprint, providing an isothermal Newtonian elastohydrodynamic solution of hypoid gears at high loads, representative of automobile differentials and with angled lubricant flow into the contact. They also accounted for inlet starvation, which is another important facet of lubrication of gears, using Hamrock and Dowson's inlet starvation boundary [22].…”

“…In equation (11), the undeformed parabolic conjunctional profile is: The instantaneous radii of pinion and gear teeth are determined through TCA (Mohammadpour et al [21], see section 2.3). A key assumption made in this paper is isothermal conditions.…”