To meet stringent emission standards and improve performance of two-stroke crankcase-scavenged engines, the muffler (13) of the engine is provided with mixing means (130, 31) for mixing the exhaust gases (42) resulting from the mixture participating in combustion and gases resulting from scavenging, so that a substantially homogenous gaseous mixture is formed within the muffler (13), and means (81) for sensing oxygen concentration is located in the homogeneous gaseous mixture and are configured to provide an output value to a control unit (80) for controlling supply of fuel to the engine and thereby the air-fuel ratio in the combustion chamber (41). The muffler (13) suitably is provided with a catalytic element (140), preferably a three-way catalyst. The engine (1) preferably is a stratified charge engine.

A method of raising exhaust gas temperatures of a two-cycle uniflow scavenged engine at lower loads. At lower loads, the exhaust valves are activated with a frequency that is less frequent than every engine cycle. This exhaust valve deactivation may be combined with additional engine operating strategies, such as by using fewer than all cylinders as combusting cylinders, adjusting fueling to combusting cylinders, and reducing compressor output.

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.

Provided is an engine, including: a cylinder; a piston accommodated in the cylinder; a combustion chamber facing the piston; a sliding portion (large-diameter portion) configured to perform a stroke motion together with the piston; a hydraulic surface of the sliding portion facing a side opposite to the combustion chamber; a hydraulic chamber, which the hydraulic surface faces; and an auxiliary hydraulic chamber, which communicates with the hydraulic chamber, and has a volume changeable in accordance with a hydraulic pressure in the hydraulic chamber.

A method of injection of liquid or gaseous ammonia fuel into a reciprocating engine that includes at least two cylinders, each cylinder including a piston that moves reciprocally within that cylinder, each cylinder having a head location at one end located opposite to a compression end of the piston and defining a combustion chamber therebetween, the cylinder including at least one inlet valve through which combustion gases are fed into the combustion chamber and at least one exhaust valve through which spent combustion gases egress the combustion chamber, the piston moving the cylinder in a cycle between top dead center where the piston is located closest to the head location and bottom dead center where the piston is located furthest from the head location, and including at least one fuel injector located at or in the head location, and wherein the method comprises: injecting the ammonia fuel into the combustion chamber of each cylinder as at least one fuel jet with a timing of: after the at least one exhaust valve of the respective cylinder is substantially closed; and before the respective piston moves to at most 35 degrees, preferably at most 45 degrees, prior to top dead centre.

A mixture formation unit has a base body in which an intake channel section is formed. The intake channel section extends from a first end side of the base body to a second end side of the base body. The mixture formation unit has at least one rectilinearly extending channel which opens into the intake channel section. The channel opens at the first end side of the base body. The mixture formation unit is preferably provided for a two stroke engine whose intake channel is divided downstream of the mixture formation unit into a mixture channel and an air channel.

A mixture formation unit has a base body in which an intake channel section is formed. The intake channel section extends from a first end side of the base body to a second end side of the base body. The mixture formation unit has at least one rectilinearly extending channel which opens into the intake channel section. The channel opens at the first end side of the base body. The mixture formation unit is preferably provided for a two stroke engine whose intake channel is divided downstream of the mixture formation unit into a mixture channel and an air channel.

Provided is an engine system including: a bypass pipe (bypass flow passage) connecting an upstream side and a downstream side of the turbine on an exhaust flow passage; a bypass valve configured to open and close the bypass flow passage; and a catalytic activation controller configured to control the bypass valve and a compression ratio of a combustion chamber.

A 2-cycle internal combustion engine in which the intake cycle begins before and ends after the exhaust cycle, resulting in a longer power stroke, increased torque and greater efficiency is disclosed herein. In the preferred embodiment, the 2-cycle engine has a power stroke of about 160 degrees, an exhaust stage of about 70 degrees, and an intake cycle of about 110-115 degrees.