A fast post-immersion restart system for a marine propulsion unit

摘要

A marine propulsion unit comprises a cylinder (1), a combustion chamber (2) extending from one end of the combustion chamber, a spark plug (8) provided in the combustion chamber (2), and a piston (5) mounted for reciprocating movement within the cylinder (1).A first port (9) is provided in the combustion chamber (2), and this is selectively openable independent of the position of the piston (5) within the cylinder (1). If the propulsion unit should be immersed in water so that the cylinder becomes flooded, the cylinder can be purged by opening the port (9) and moving the piston (5) so as to expel water through the port (9). Once all water has been expelled further movement of the piston causes gases in the cylinder to pass over the spark plug thus removing trapped water from the spark plug without the need to remove the spark plug from the engine to dry it. The location of the first port is chosen so as to maximise as far as possible the flow of gas over the spark plug (8), to minimise the time taken to remove trapped water from the spark plug. Once the spark plug has been dried sufficiently to allow ignition to be achieved, the propulsion unit can be restarted.A second port (10) can also be provided to improve drainage of the engine.