US Patent 11333068 Side wall for rotary engine housing

A housing for a rotary engine has: a peripheral wall defining two end faces and an inner face transverse to the two end faces; two side walls sealingly engaged to the two end faces of the peripheral wall, a core of a side wall of the two side walls having a core face, the core face having a cavity section facing the rotor cavity and an abutment section annularly extending around the cavity section, the abutment section facing an end face of the two end faces, the abutment section having a flared portion flaring away from the end face; and a coating on the core face, the coating made of a material harder than a material of the core of the side wall, the coating covering the cavity section and ending at a coating edge located on the flared portion, the coating edge free of contact with the end face.