Patent ID: 8910613
Filing Date: 2014-12-16
Classification: F02B,Y02T

Abstract:
1. An internal combustion engine, comprising: a first cylinder with a first piston slidably disposed in the first cylinder, the first cylinder defining a combustion chamber having a first diameter; the first piston having a first stroke; an expansion cylinder adjacent to the first cylinder, with a second piston slidably disposed in the expansion cylinder, the expansion cylinder defining an expansion chamber having a second diameter; the first piston of the first cylinder is between about 180-190 degrees out of phase with the second piston of the expansion cylinder; an exhaust passage fluidly connecting the combustion chamber and the expansion chamber; one or more valves controlling the flow of gas from the combustion chamber to the expansion chamber through the exhaust passage; wherein the second diameter is larger than the first diameter and/or the second piston has a second stroke that is larger than the first stroke; a vent passage on the expansion cylinder that fluidly communicates the expansion chamber with atmosphere, and a check valve on the expansion cylinder that controls flow through the vent passage, the check valve is biased by a spring to a closed position preventing flow through the vent passage, the check valve is movable against the bias of the spring to an open position so that the expansion cylinder fluidly communicates with atmosphere, and a spring force provided by the spring is such that the check valve automatically opens if a negative pressure develops in the expansion chamber so that atmospheric pressure is greater than the negative pressure in the expansion chamber to equalize pressure in the expansion chamber with atmospheric pressure.