IMPROVEMENTS IN OR RELATING TO RECIPROCATING PISTON ENGINES

摘要

A reciprocating piston engine is described. The engine has a cylinder with a transfer port (22) and an exhaust port (24), whereby the transfer port (22) and the exhaust port (24) are at least partially coincident and are provided with a port valve (26). The engine further comprises a pump (32) having a divided chamber (38) therein, one side of the chamber being connected to a crankcase (30) via a connecting port (34), and the other side of said chambe r having an inlet port (40), an outlet port (41) and a valve means (42, 44) to ensure unidirectional flow therethrough, wherein said chamber is divided by a moving member (36) responsive to variations in pressure in said crankcase (3 0) to cause flow through said other side of the chamber.