US Patent 7296544 Internal combustion engine

A four stroke internal combustion engine (110) having at least one cylinder (13) having a double acting piston (16) dividing the cylinder into two combustion chambers (14 & 15) and being reciprocable within the cylinder (13) to perform a power stroke producing work on a crankshaft (21) whilst moving towards or away from the crankshaft. The piston (16) has a pivotal connection (30) with a connecting rod (17) in turn connected directly to the crankshaft (21). A separation plate (18) separates the engine sump (12) from the adjacent combustion chamber (15) and accommodates lateral movement of the connecting rod (17) passing sealingly therethrough.