A gear rattle model accounting for oil squeeze between the meshing gear teeth

Abstract

In this paper a non-linear one-degree-of-freedom model for analysis of gear rattle vibrations in automotive manual transmissions is presented. In order to take into account the damping effects owing to the oil in the gap between two teeth of a meshing gear, a simple one-dimensional model for the oil-film squeeze effects is proposed. The squeeze model assumes that the damping force is proportional to the oil viscosity and to the extension of the oil film in the plane of curvature of the teeth, which may depend on the lubrication conditions (dry sump, splash, bath). The results provided from several numerical simulations, carried out with reference to helical involute tooth pairs, confirm the capability of oil in reducing the high-frequency vibrations subsequent to the impact between the teeth. In particular, the influence exerted by oil viscosity and gap extension on the rattle characteristics is investigated through the analysis of the transient response of the driven gear by imposing a harmonic motion to the driving gear

Non-Newtonian mixed thermo-elastohydrodynamics of hypoid gear pairs

“…8 Reduced friction often leads to repetitive impacts of gear teeth pairs or contact separation, thus loss of traction. 9,10 Lubricant is subjected to changes in the regime of lubrication as shown by De la Cruz et al 11 In automotive transmissions and differential gearing, thin films promote mixed thermo-elastohydrodynamic regime of lubrication. Therefore, friction is generated as the result of viscous shear of lubricant as well as counterface asperity interactions.…”

An investigation of manual transmission drive rattle

“…The repetitive impacts between teeth are governed by the low stiffness of the lubricant film and not by the Hertzian effective stiffness of mating gear teeth pairs [4]. For drive rattle, the engaged gear pairs experience higher contact loads and operate under the elastohydrodynamic regime of lubrication.…”

Non-linear vibro-impact phenomenon belying transmission idle rattle

“…Other contact models have included time-varying piecewise linear stiffness functions [2], or have used the classical Hertzian theory [8] or other time-varying functions [9,10]. In the aforementioned models, damping has been mainly included as drag torque between the loose gear and its retaining shaft in the system [3,5,11,12] with constant coefficients or those proportional to the penetration velocity (mutual convergence of gear teeth flanks) [7][8][9].…”

“…In the aforementioned models, damping has been mainly included as drag torque between the loose gear and its retaining shaft in the system [3,5,11,12] with constant coefficients or those proportional to the penetration velocity (mutual convergence of gear teeth flanks) [7][8][9]. The effect of lubricant film squeeze action has been considered by Brancati et al [10] and Gnanakumarr et al [13]. Brancati et al [10] assumed non-linear damping due to a squeeze film adsorbed on the teeth.…”

“…The effect of lubricant film squeeze action has been considered by Brancati et al [10] and Gnanakumarr et al [13]. Brancati et al [10] assumed non-linear damping due to a squeeze film adsorbed on the teeth. On the other hand, in reference [13], no metal-to-metal contact was considered.…”