Conceptual design optimisation of a constant-velocity coupling

•A simple spherical geometry model of the Thompson coupling has been presented.•Parameter study carried out using flexible design variables in Thompson coupling.•Whilst the rigid body dynamics is possible, proposed model is simple and flexible.

The Thompson Coupling is a novel constant velocity joint that operates using the robust double Cardan mechanism. Constant velocity and determinate linkage kinematics are maintained by a spherical pantograph. This mechanism forms an extra loop attached to the intermediate shaft in the double Cardan linkage, and consequently constrains this shaft to bisect the axis of input and output. To date, there has been little presented on the closed-form kinematics of this component. Closed-form expressions for its motion and the rotation of the double Cardan joint are derived by consideration of spherical linkage kinematics, and presented in this work. These expressions are then used to drive basic conceptual design optimisation, whose goal is to reduce induced driveline vibration. The findings of this optimisation are discussed with respect to the current design of the Thompson joint. Improvements in induced driveline vibration are possible, subject to the satisfaction of other coupling design criteria.