Internal combustion engine

An internal combustion engine unit including an engine block which has a single combustion chamber, a boost chamber and a single piston constrained to have rocking motion about a pivot axis within said engine block, wherein:

• said piston has a first arcuate sealing surface and a second arcuate sealing surface radially offset from said first arcuate sealing surface with both said surfaces transcribing a circumferential path about said pivot axis, the piston including a floor extending substantially radially between said first arcuate sealing surface and said second arcuate sealing surface;
• said combustion chamber has four walls;
• one wall of the combustion chamber being of arcuate formation which describes a circumferential path from said pivot axis and against which said first arcuate sealing surface of the piston can seal;
• and another wall of the combustion chamber being formed by said second arcuate sealing surface of said piston;
• the second arcuate sealing surface of the piston seals the combustion chamber from the boost chamber and wherein a primary transfer duct provides communication between an induction chamber situated below the piston and the combustion chamber through a port in the one wall of the combustion chamber which is uncovered by the piston when the piston has reached a predetermined position within the combustion chamber to enable an air/fuel charge to pass from the induction chamber into the combustion chamber,
• an exhaust port in the one wall of the combustion chamber adapted to be uncovered by the piston when the piston has reached a predetermined position within the combustion chamber whereby combustion gases can exit the combustion chamber.

An internal combustion engine unit having:

• a) a single combustion chamber, b) a single piston pivoted on a pivot and forming part of the combustion chamber, c) a transfer port to admit a gaseous charge into the combustion chamber, d) an exhaust port to exhaust gas from the combustion chamber, and e) a connection between the piston and a crankshaft, wherein:
• the piston has a first arcuate surface and a second arcuate surface radially offset from said first arcuate surface with both said surfaces transcribing a circumferential path about the piston pivot, the piston including a floor extending substantially radially between the first arcuate surface and the second arcuate surface;
• the combustion chamber is formed by walls, a first wall being of arcuate formation and describing a circumferential path from said piston pivot and against which the first arcuate surface of the piston can seal;
• and
• a second wall of the combustion chamber being of arcuate formation and describing a circumferential path from said piston pivot and against which the second arcuate surface of the piston can seal.

An internal combustion engine unit which includes:

• a) a single combustion chamber, b) a boost chamber, and c) a single piston pivoted about a pivot axis and connected to a crankshaft housed within an induction chamber situated below the piston, wherein:
• i) an exhaust port and a transfer port are formed in a wall of the combustion chamber and are each adapted to be alternately sealed from the combustion chamber and opened to the combustion chamber by the piston when the piston has reached a predetermined position within the combustion chamber,
• ii) the piston has a first arcuate surface and a second arcuate surface radially offset from said first arcuate sealing surface with both said surfaces transcribing a circumferential path about said pivot axis, the piston including a floor extending substantially radially between said first arcuate surface and said second arcuate surface;
• and
• iii) the combustion chamber has walls, one wall being of arcuate formation which describes a circumferential path from said pivot axis and against which said first arcuate surface of the piston can seal and another wall being of arcuate formation which describes a circumferential path from said pivot axis and against which said second arcuate surface of said piston can seal in a manner such that a seal is maintained between the combustion chamber and the boost chamber.