A two-stroke engine with valves near bottom dead center that are adapted to prevent intake charge from exiting exhaust ports, wherein the valves are actuated by air pressure difference.

A two-stroke engine with valves near bottom dead center that are adapted to prevent intake charge from exiting exhaust ports, wherein the valves are actuated by air pressure difference.

A new engine which incorporates the advantages found in a two-stroke with the advantages found in a four-stroke engine combined.

A new engine which incorporates the advantages found in a two-stroke with the advantages found in a four-stroke engine combined.

A two-stroke engine includes: a scavenging port communicating with a crank chamber and a side portion of a cylinder, and switchably brought into communication with or shut off from the cylinder by a piston; and multiple fuel injection valves for injecting fuel into the scavenging port. Since the fuel injection valves inject fuel into the scavenging port, there is no need to apply a high pressure injection system. By causing the start of fuel injection to be delayed from a timing at which the scavenging port is opened, fresh air is sent into the cylinder at an early stage of scavenging, and air-fuel mixture is sent into the cylinder at a late stage of scavenging. Thereby, even in a long-stroke engine, stratified scavenging is performed to suppress blow-by of air-fuel mixture.

A two-stroke engine includes: a scavenging port communicating with a crank chamber and a side portion of a cylinder, and switchably brought into communication with or shut off from the cylinder by a piston; and multiple fuel injection valves for injecting fuel into the scavenging port. Since the fuel injection valves inject fuel into the scavenging port, there is no need to apply a high pressure injection system. By causing the start of fuel injection to be delayed from a timing at which the scavenging port is opened, fresh air is sent into the cylinder at an early stage of scavenging, and air-fuel mixture is sent into the cylinder at a late stage of scavenging. Thereby, even in a long-stroke engine, stratified scavenging is performed to suppress blow-by of air-fuel mixture.

A turbocharger for an engine includes a housing, a shaft, a turbine wheel mounted to the shaft for rotation therewith, a compressor wheel mounted to the shaft for rotation therewith, and a bearing cartridge rotatably supporting the shaft relative to the housing. The housing is positioned axially between the turbine and compressor wheels. The bearing cartridge includes an inner ring mounted to the shaft, an outer ring disposed between the inner ring and the housing and movable relative to the housing, and a first and a second plurality of roller elements axially spaced apart from one another and disposed radially between the inner and outer rings to rotatably support the inner ring relative to the outer ring. A radial gap (RD) is defined between the outer ring (134) and the housing (126). Lubricant flows into the radial gap and radially separates the outer ring from the housing during operation of the turbocharger.

A turbocharger for an engine includes a housing, a shaft, a turbine wheel mounted to the shaft for rotation therewith, a compressor wheel mounted to the shaft for rotation therewith, and a bearing cartridge rotatably supporting the shaft relative to the housing. The housing is positioned axially between the turbine and compressor wheels. The bearing cartridge includes an inner ring mounted to the shaft, an outer ring disposed between the inner ring and the housing and movable relative to the housing, and a first and a second plurality of roller elements axially spaced apart from one another and disposed radially between the inner and outer rings to rotatably support the inner ring relative to the outer ring. A radial gap (RD) is defined between the outer ring (134) and the housing (126). Lubricant flows into the radial gap and radially separates the outer ring from the housing during operation of the turbocharger.

A two-stroke internal combustion engine includes: a piston-cylinder group defining a combustion and a pumping chamber, the piston mobile in the cylinder between a bottom dead center where the combustion chamber's volume is maximum and the pumping chamber's volume is minimum, and a top dead center, where the combustion chamber's volume is minimum and the pumping chamber's volume is maximum. The engine also includes an intake conduit communicating with the pumping chamber, an exhaust conduit communicating with the combustion chamber, at least a pair of transfer conduits allowing communication between the pumping and combustion chambers, and at least two primary channels in the piston, individually provided with an inlet facing onto the exhaust conduit and an outlet facing on a respective transfer conduit at least when the piston is at the top dead center. A lateral surface of the piston includes a lowering where the primary channels inlets are located.

A two-stroke internal combustion engine includes: a piston-cylinder group defining a combustion and a pumping chamber, the piston mobile in the cylinder between a bottom dead center where the combustion chamber's volume is maximum and the pumping chamber's volume is minimum, and a top dead center, where the combustion chamber's volume is minimum and the pumping chamber's volume is maximum. The engine also includes an intake conduit communicating with the pumping chamber, an exhaust conduit communicating with the combustion chamber, at least a pair of transfer conduits allowing communication between the pumping and combustion chambers, and at least two primary channels in the piston, individually provided with an inlet facing onto the exhaust conduit and an outlet facing on a respective transfer conduit at least when the piston is at the top dead center. A lateral surface of the piston includes a lowering where the primary channels inlets are located.