Efficiency modelling in the full toroidal variator: Investigation into optimisation of EHL contact conditions to maximize contact efficiency.

Numerical insight into heat transfer and power losses in spinning EHD non-Newtonian point contacts

“…10 together with the total heat generated in the contact calculated by the triple integration of equations (18) and (19) for U 1,x,0 ¼ 1.9 m/s and U 2,x,0 ¼ 2.1 m/s. The repartition between sliding losses and spin losses is particularly of interest and shows a similar behaviour to the experimental work of Newall et al [27]. As spin increases, sliding losses decreases due to decrease in viscosity (Table 5), which is equivalent to a decrease of the longitudinal friction, as in Fig.…”

“…Thus, transverse friction may give complementary information [14], but considering these two parameters only may not reflect the physical mechanism of shearing which is direction independent, as shown in equations (13) and (19). As an alternative to longitudinal and transverse frictions, power losses are introduced in a way similar to Newall et al [27]. It reflects in a more accurate way the internal dissipation occurring within spinning EHD contacts, taking into account the Fig.…”

“…Power losses (PL) include sliding power losses describing x and y force losses due to constant sliding along x and y directions and spin power losses describing torque losses due to spin. The expression for power losses can be calculated as follows and leads to a similar expression to the one used by Newall et al [27] PL ¼…”

A Mathematical Method for Eliminating Spin Losses in Toroidal Traction Drives

“…The Spin Losses. Efficiency losses of the Toroidal CVTs consist of bearing losses, spin losses, churning losses, and slip losses [9]. Churning losses are often neglected by researchers because of their small magnitude compared with other losses [16,25].…”

“…Full-Toroidal CVTs, which were first proposed in 1877 [7], can transmit higher torque than that of the Friction CVTs [8]. However, their efficiency losses are up to 9% to 11% [9] because of spin losses induced by the different speed distributions in the contact area [10]. To overcome this drawback, Kraus modified the geometry and proposed the Half-Toroidal CVTs [11], which have been demonstrated to reduce the spin losses greatly and control their total efficiency losses below 5% to 7% [12].…”