Internal combustion engine

Claim 1

An internal combustion engine comprising a main combustion chamber communicating with a subsidiary combustion chamber and flow control means for controlling fluid flow between these, the control means being effective to at least provide a substantial restriction to communication between the combustion chambers, prior to ignition of a subsidiary air fuel charge introduced into the subsidiary combustion chamber in use of the engine, and to subsequently effect relief of said restriction whereby ignited said subsidiary air fuel charge is caused to pass to said main combustion chamber via a passageway extending from the subsidiary combustion chamber to effect ignition of a main working fluid charge in the main combustion chamber, the igniting working fluid charge then expanding against a moveable part of the engine to effect operation thereof, wherein said control means comprises a cylindrical element moveable in a lengthwise direction of said passageway and arranged to execute lengthwise reciprocatory motion when the engine is operated, said element having a radially outwardly directed peripheral surface portion thereon which portion is caused to be moved into adjacent relationship with a complementary peripheral surface portion of the passageway, during said reciprocatory movement, whereby to effect said at least substantial restriction of communication between the combustion chambers and is caused to be moved away from said surface portion of the passageway during said reciprocation to present clearance between the surface portions for effecting said relief of said restriction, and further wherein said element is arranged to move through said passageway, during said reciprocation, whereby to be clear of the surface portion of the passageway respectively at respective opposite extremes of the reciprocatory movement, whereby the control means is in an open condition at such extremes and in a substantially closed condition at an intermediate position between said extremes.