Patent ID: 6158401
Filing Date: 2000-12-12
Classification: F02B

Abstract:
A method of operating a free piston internal combustion engine, comprising the steps of:providing a housing including a combustion cylinder and a hydraulic cylinder;providing a piston including a piston head reciprocally disposed within said combustion cylinder, a plunger head reciprocally disposed within said hydraulic cylinder, and a plunger rod interconnecting said piston head with said plunger head, said plunger head and said hydraulic cylinder defining a variable volume pressure chamber on a side of said plunger head generally opposite said plunger rod;pulsing a supply of hydraulic fluid from a high pressure hydraulic accumulator into said pressure chamber during a beginning portion of a compression stroke to cause said piston head to move toward a top dead center position;decoupling said high pressure hydraulic accumulator from said pressure chamber; andcoupling a low pressure hydraulic accumulator with said pressure chamber during a remaining portion of said compression stroke, thereby allowing a relatively lower pressure hydraulic fluid to flow into said hydraulic cylinder as said piston head moves toward said top dead center position.