Piston sealing mechanism for a circulating piston engine

An engine, comprising:

• a housing;
• a combustion assembly carried by the housing, the combustion assembly comprising:
• an annular bore defined by the housing,
• at least one combustion piston disposed within the annular bore, and
• a sealing mechanism positionable between a retracted position and an extended position relative to the at least one combustion piston and configured to selectively seal the at least one combustion piston relative to at least one corresponding wall of the annular bore;
• and
• at least one rotary valve configured to move between a first position within the annular bore to allow the at least one combustion piston to travel within the annular bore from a first location proximate to the at least one valve to a second location distal to the at least one rotary valve and a second position within the annular bore to define a combustion chamber relative to the at least one combustion piston at the second location.