Patent ID: 7469664

Claim:
An internal combustion engine comprising: an inner and outer piston disposed in each of a pair of cylinders, one end of the outer piston cooperating with the cylinder to form a combustion chamber, the other end of the outer piston coupled to a plunger that moves in unison with the piston; a scavenging pump disposed at the end of a cylinder, the scavenging pump comprising first and second chambers defined by the movable plunger; wherein the pump is configured to draw fluid into the first chamber from outside the pump when the outer piston is moving toward the inner piston, and to direct the fluid from the first chamber into the second chamber, pressurizing it, when the outer piston is moving away from the inner piston; and wherein the pressurized second chamber is able to communicate with the intake ports of both cylinders so that the pressurized fluid is directed into each when intake ports are opened.