Patent ID: 8505504

Claim:
A two-stroke engine comprising: a crankshaft rotatable about an axis; an engine block including a combustion cylinder and a compression cylinder; a first piston slidably disposed within said combustion cylinder and coupled to a first connecting rod which is coupled to said crankshaft for reciprocating movement within said combustion cylinder through a power stroke during each rotation of said crankshaft about said axis; a second piston slidably disposed within said compression cylinder and coupled to a second connecting rod which is coupled to said crankshaft for reciprocating movement within said compression cylinder such that fresh air is received and compressed in said compression cylinder during each rotation of said crankshaft about said axis; a conduit providing fluid communication between said combustion cylinder and said compression cylinder; a fuel injector in communication with said combustion cylinder for admitting fuel into said combustion cylinder; first and second rotary valves in said engine block and operatively coupled to said crankshaft for rotation relative to said crankshaft, said first and second rotary valves being respectively rotatable to selectively admit fresh air into said compression cylinder and to permit the flow of compressed air into said conduit; and said first and second rotary valves operable such that air compressed in said compression cylinder is transferred through said conduit to said combustion cylinder and scavenges substantially all contents of said combustion cylinder before fuel is admitted to said combustion cylinder by said fuel injector; wherein said conduit is open to said combustion cylinder during scavenging; wherein said conduit defines a first volume for holding air and said combustion cylinder defines a first maximum volume for holding a mixture of air and fuel, said first volume of said conduit being sufficient to displace a volume at least as great as said first maximum volume of said combustion cylinder.