Patent ID: 7793635

Claim:
A rotary piston type internal combustion engine comprising an output shaft, a rotor coupled to said output shaft with no relative rotation, a housing rotatably supporting said output shaft, an annular operation chamber formed by said rotor and housing for forming an intake operation chamber, a compression operation chamber, a combustion operation chamber and an exhaust operation chamber, at least one pressuring/pressured member provided to said rotor for partitioning said annular operation chamber and for compressing intake air in the compression operation chamber and receiving gas pressure of combustion gas in the combustion operation chamber, at least one operation chamber partitioning member provided to said housing for partitioning said annular operation chamber, an intake port for introducing intake air into said annular operation chamber, an exhaust port for exhausting gas from said annular operation chamber, and a fuel supply means for supplying fuel, wherein compressed fuel-air mixture is ignited using a spark plug or compression ignition; said annular operation chamber is formed by at least one of sidewall portions of said rotor in an axial direction of said output shaft and said housing, and has an entirely or mostly cylindrical inner peripheral wall and an entirely or mostly cylindrical outer peripheral wall; said operation chamber partitioning member comprising a reciprocating partitioning member that reciprocates in parallel to an axis of said output shaft between an advanced position where it partitions said annular operation chamber and a retracted position where it is retracted from said annular operation chamber; a biasing means for biasing said reciprocating partitioning member toward said advanced position; said pressuring/pressured member comprising an arc-shaped partitioning member having a first inclined surface for driving said reciprocating partitioning member from said advanced position to said retracted position, a forefront sliding surface continued from said first inclined surface, and a second inclined surface continued from said forefront sliding surface and allowing said reciprocating partitioning member to return from said retracted position to said advanced position; wherein said annular operation chamber has a rectangular half section with arc-like rounded corners in a plane containing the axis of said output shaft and is constituted by a shallow annular groove formed in said rotor and a deep annular groove formed in said housing; wherein said shallow annular groove has a first annular wall on a plane orthogonal to the axis of said output shaft and inner and outer corner walls that are on an inner peripheral side and on an outer peripheral side of said first annular wall; and wherein said deep annular groove has an inner cylindrical wall, an outer cylindrical wall, a second annular wall on a plane orthogonal to the axis of said output shaft, and inner and outer corner walls that are on an inner peripheral side and on an outer peripheral side of said second annular wall.