Internal combustion engine

Claim 1

In an internal combustion engine operable using a cycle having expansion, exhaust, intake and compression phases, which engine comprises at least one pair of opposed pistons which reciprocate in cylinder portions which are in fluid communication with each other via a common combustion chamber, the pistons being coupled to respective cam elements engaged with a common output shaft for converting the reciprocating motion of the pistons into rotational motion, and the cylinder portions having intake and exhaust ports in the cylinder walls arranged such that each intake port is engaged by one piston and each exhaust port is engaged by the respective opposed piston; the improvement comprising that the cam elements are provided with different cam profiles profiled at least along those cam portions proceeding the closing of the intake port to cause the respective pistons to uncover the respective exhaust and inlet ports in a timed sequence such that an exhaust stroke length formed between the opposed pistons when the exhaust port is initially opened, is longer than an intake stroke length formed between the opposed pistons when the inlet port is closed, at which time the exhaust port engaging piston has moved from the exhaust port by an amount of at least 10% of a distance from the exhaust port to the center of the common combustion chamber at ignition to produce a sufficient increase in effective volume of the expansion phase with respect to the intake phase to give hyper-expansion.