Parameter study on the influence of a radial groove design on the drag torque of wet clutch discs in comparison with analytical models

A considerable part of the power loss in disengaged wet clutches is caused by viscous shearing of the cooling oil between the clutch discs. Reducing this drag loss as far as possible is the objective of current research. This contribution deals with the measurement and analytical computation of the drag torque of a clutch disc with radial grooving. Operating parameters and diverse geometrical parameters such as groove width, depth, angle, or number are varied. A newly developed single-disc test rig by which the dependencies of the drag torque are able to be examined is used for measuring. Conclusions to the cause of the fluid flow behaviour are drawn and the results are compared to analytical calculation models.