Clutch assembly for a hybrid-electric aircraft propulsion system

A method for coupling an engine of an aircraft propulsion system with a propulsor, the propulsor driven by an output shaft, an engine drive gear driven by the engine decoupled from the output shaft by a clutch assembly in a disengaged state, the method comprising:

• driving rotation of the propulsor about a rotational axis with an electric machine coupled with the propulsor by the output shaft;
• coupling the engine with the propulsor by axially moving a coupling piston disk mounted about the output shaft from a decoupled axial position to a coupled axial position, the coupling piston disk in the coupled axial position contacting a plurality of sliding pads having obliquely oriented pad body surfaces and radially compressing the sliding pads against a clutching surface on the engine drive gear to couple the engine drive gear with the output shaft;
• and
• driving rotation of the propulsor about the rotational axis with the engine.

An aircraft propulsion system comprising:

• an engine;
• an electric machine;
• and
• a gearbox including an output shaft, an electric machine drive gear, an engine drive gear, and a clutch assembly, the output shaft having a rotational axis, the electric machine drive gear mounted on the output shaft, the electric machine drive gear driven by the electric machine, the engine drive gear selectively couplable with the output shaft by the clutch assembly,
• the clutch assembly including a bearing, a coupling piston disk, and a plurality of sliding pads, the bearing disposed between the output shaft and the engine drive gear, the engine drive gear rotatable relative to the output shaft on the bearing, the clutch assembly selectively coupling the engine drive gear with the output shaft, the clutch assembly configurable in a disengaged state and an engaged state, the engine and the engine drive gear decoupled from the output shaft in the disengaged state of the clutch assembly, the engine and the engine drive gear coupled with the output shaft in the engaged state of the clutch assembly by axial movement of the coupling piston disk to radially compress the plurality of sliding pads against a clutching surface on the engine drive gear, and
• the output shaft structured to drive a propulsor.