Frictional power losses on spur gears with tip reliefs. The load sharing role

Abstract

The load sharing impact on the efficiency of spur gears with modified profile was assessed in this work. The aim was to analyse the influence of the profile modifications on the load sharing, which also considers the effect of the torque level on the system deflections, and how these load sharing variations affected the system efficiency. Due to the frictional effect importance on power losses, in the operating conditions considered, sliding friction between teeth in presence of lubricant was studied in this proposal. The results established that tip relief improves the efficiency of the system due to the reduction of effective contact ratio. Moreover, there is a tip relief which makes optimal the efficiency in specific operating conditions, corresponding to the unit value of the effective contact ratio. Thus, the main conclusion of this work is that the tip relief which makes optimal the efficiency coincides with the theoretical dynamic optimum of the transmission.

Investigation on the wear of spur gears generated by modified cutter

“…The maximum pressure at each contact point can be calculated based on the Hertzian contact model [45,46] as follows:…”

Frictional power losses on spur gears with tip reliefs. The friction coefficient role

“…Sliding friction formulation follows the Coulomb ′ s model. This is the reason why power losses are dependent of the friction coefficient (µ (θ)), sliding velocity factor ( Vs(θ) V ) and load sharing ( [9,10], where V is the pitch line velocity, θ the rotation angle and F N max the maximum normal force. Their multiplication is denominated as Instantaneous Power Loss (IP L) factor (equation 1).…”

“…As something worth of mention, this LCM takes into account the torque level and profile modification effects on the friction coefficient and load sharing. This LCM has been previously developed by the authors [13,16,44], extended to the modelling of planetary gears [20,21] and currently used to calculate the efficiency of spur gear transmissions [9,10]. This LCM allows for including profile modifications, which affect directly the dynamic behaviour and efficiency of the system, as well as opens the possibility of studying manufacturing and assembly errors [14,15] effects on power losses.…”

“…This LCM allows for including profile modifications, which affect directly the dynamic behaviour and efficiency of the system, as well as opens the possibility of studying manufacturing and assembly errors [14,15] effects on power losses. As commented, this proposal is mainly focused on the friction coefficient role in the efficiency of this kind of gear transmissions, since the load sharing role was analysed before [10]. This is the reason why two friction coefficient formulations have been implemented.…”

Tribological and thermal properties of a crowned gear pair with high-speed and heavy-load in thermal micro-elastohydrodynamic lubrication

“…investigated the effects of load sharing and friction coefficient of a tip relief spur gear pair on frictional power loss. 22,23 Marques et al. 24 studied the power loss of standard spur and helical gears based on load distribution model with the frictional effect.…”