Patent ID: 8662031

Claim:
A through-scavenging two-stroke engine comprising at least: a crankcase; a cylinder forming a combustion chamber therein, the cylinder is mounted on the crankcase; a cylinder head sealing one side of the combustion chamber, the cylinder head is comprising an exhaust port and an exhaust poppet valve controlling the exhaust port; a crankshaft rotatably mounted to the crankcase; a connecting rod; a piston reciprocally disposed into the cylinder, the piston is sealing another side of the combustion chamber; the piston is comprising a piston skirt, a piston crown secured at one end of the piston skirt and a wrist pin secured at the other end of the piston skirt; the piston skirt is having an outer surface adjacent the cylinder and an inner surface; the connecting rod is pivotally mounted to the piston by the wrist pin, the connecting rod is drivingly coupling the piston to the crankshaft; a substantially immovable shell is disposed inside the piston skirt between the piston crown and the wrist pin so that the wrist pin and the piston crown move at opposite sides of the substantially immovable shell; the inner surface of the piston skirt is reciprocally disposed around the substantially immovable shell; the piston crown is comprising an intake port and an intake poppet valve having a restoring valve spring; the intake poppet valve is controlling the intake port; the combustion chamber is communicating, through the intake port, with a space underside the piston crown; the space underside the piston crown is being inside the piston skirt between the piston crown and the substantially immovable shell; the substantially immovable shell is comprising a port feeding air or mixture to the space underside the piston crown; the space underside the piston crown is sealed from the crankcase; and an oil scraper is scrapping most of the oil supplied to the inner surface of the piston skirt back to the crankcase from where it is cleaned and recycled.