Variations of a Wankel engine

For a triangular Wankel rotor, the ratio between gear and gear ring must be a constant 2:3, for a square rotor 3:4, for a pentagonal rotor 4:5, and for a hexagonal rotor 5:6. This is ensured here by hidden constraints. The trajectory of one corner (or rather: the identical trajectories of all corners) of the rotor then generate the required contour of the combustion chamber.