Patent ID: 8578895
Filing Date: 2013-11-12
Classification: F02B,F02D,Y02T

Abstract:
1. A two-stroke engine composed of: a) a crankcase defining at least one engine cylinder; b) an injector for direct injection of fuel into the engine cylinder; c) an engine piston mobile inside the engine cylinder between a top dead center and a bottom dead center; d) a crankshaft supported in the crankcase with at least two bearings and including at least one crank pin, at least a first connecting rod hinged to the engine piston and directly to the crank pin of the crankshaft; e) an air pump, the air pump including a pump cylinder housed in the engine, a pump piston sliding in the pump cylinder, and a second connecting rod hinged to the same crank pin of the crankshaft as the first connecting rod; f) a main pipe connected to the air pump communicating with the engine cylinder through a plurality of scavenging pipes opening into said cylinder through respective scavenging ports placed immediately above the piston in its bottom dead center position; g) an exhaust pipe opening into the cylinder through an exhaust port located immediately above the piston in its bottom dead center position; h) at least one auxiliary pipe connected to a source of pressurized air and flowing into said cylinder at a level higher than the scavenging pipes and exhaust pipes, the auxiliary pipe stemming from the main pipe; i) a valve to selectively open and close the auxiliary pipe once in every cycle of the two-stroke engine, for supercharging during operation and for decompression to reduce a resisting torque at engine start-up, the valve being a rotary valve sealingly coupled to a cylindrical seat intersecting the auxiliary pipe and having at least one tangential groove capable of selectively aligning itself with the main pipe, the valve including a channel configured to allow exhaust gases to re-circulate from the cylinder through the auxiliary pipe, before the exhaust port is opened; and j) a phase transformer associated with the valve and configured to turn the valve by a given angle, to exclude supercharging under partial load conditions.