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.

The disclosure provides a two-cycle engine and an engine work machine. When a piston is located on the side of a bottom dead center, at a part corresponding to a notch part in the piston, an inner surface of the crank case protrudes toward an interior side to form a crank case first protruding part penetrating through the notch part toward the interior side. Meanwhile, the crank case at a part corresponding to a part without the notch part in the piston is not in a shape protruding toward the interior side. By assembling the piston and the crank case in such shapes, the piston is able to reciprocally move up and down without interfering with the crank case. In this case, by disposing the crank case first protruding part, the volume in the crank case is able to be reduced.

An air handling arrangement in a two-stroke cycle, opposed-piston engine with uniflow scavenging and constructed for heavy-duty operation includes sequentially arranged turbochargers in series with a supercharger. In some aspects, the air handling system is equipped with an EGR channel.

A scavenger valve and method of directing gas in a two stroke engine are provided involving poppet elements in a scavenger valve with specific multiple, different flow paths from individual poppet heads.

A method for controlling a two-stroke engine operatively connected to a turbocharger, the turbocharger being in fluid communication with the engine to provide a boost pressure thereto, the method including: comparing one of (i) an actual power output of the engine; and (ii) an exhaust temperature representative of an actual temperature of exhaust gas being discharged by the engine, with a corresponding threshold value thereof; in response to the one of the actual power output of the engine and the exhaust temperature being less than the corresponding threshold value: determining a corrective amount of boost pressure to add to the boost pressure of the turbocharger; and controlling the turbocharger to increase the boost pressure of the turbocharger by the corrective amount. Another method for controlling a two-stroke engine operatively connected to a turbocharger is also disclosed.

The invention relates to a method (100) for controlling a powertrain system (10) of a vehicle (1) during gear upshifting, said powertrain system comprising: an internal combustion engine system (11) comprising an internal combustion engine (12) configured to output a rotational speed (W1) via an engine output shaft (8); a transmission arrangement (14) having a number of gear stages to obtain a set of gears, the transmission arrangement being operatively connected to the internal combustion engine via a transmission input shaft (64) and further having a transmission output shaft (24) for providing a rotational speed to one or more drive wheels (26) of the vehicle; the method comprising the steps of: operating (110) the engine in a four-stroke operation to provide engine rotational speed output via the engine output shaft; receiving (120) an indication of an intended upshifting from a gear of the set of gears to a higher gear of the sets of gears; reducing (130) the rotational speed of the engine output shaft by adjusting the operation of the engine from the four-stroke operation to a two-stroke braking operation; and, when said engine is in the two-stroke braking operation, performing (140) the intended upshifting from said gear of the set of gears to said higher gear of the sets of gears.

A piston ring is provided, in particular a compression piston ring having at least one recess with a lower edge running obliquely to the upper piston ring flank on its upper piston ring flank, the ring flank extending radially outward from the piston ring interior and radially inward from the piston ring bearing surface. The piston ring has a chamfer, which is opposite at least one recess. At least one recess and the chamfer extend in the radial direction up to at most the center of the cross-sectional area of the piston ring.

A piston with external pins boss connected with at least two coupled crankshafts, transforming reciprocating linear movement of the piston into rotary motion of the crankshafts. A cylinder jacket with the piston head forms the combustion chamber. Piston inner space with static counterpart forms an additional intake-breathing chamber. On static counterpart, an income and outgo valves can be located. From reciprocating movement of the piston, the intake-breathing chamber will provide intake gases to the combustion chamber employing a transfer port. Previous to the transfer port, a control valve may be disposed to regulate the volume of intake gases entering the combustion chamber. The intake-breathing gases not used for combustion may be mixed with combustion exhaust gases. Length of connecting links, on inverse configuration, provides extra time at maximum compression rate; improving evaporation and combustion stage timing.

An engine assembly for a vehicle includes an internal combustion engine operating on a two-stroke engine cycle. A compressor is in fluid communication with an intake port of at least one cylinder of the engine to pump air into the engine. An exhaust pipe is in fluid communication with an exhaust port of the at least one cylinder. The exhaust pipe has an inlet and an outlet defining a length of the exhaust pipe therebetween. A diameter of the exhaust pipe increases along a portion of the length of the exhaust pipe in a flow direction of the exhaust pipe. The diameter of the exhaust pipe does not decrease along the length of the exhaust pipe in the flow direction of the exhaust pipe.

An attachment for purging the inside of the carburetors which is comprised by a tubular device having a carburetor connecting member and quick connect receiver extension. The attachment is connected through the bottom of the carburetor or through the feed fuel line of the carburetor. The attachment is attachable to a quick disconnect fitting which can be connected to a conventional car tire air nozzle or pressurized can with the same fitting as the car tire nozzle. The attachment allows all the jets and passages located on the inside of carburetor to be purged at the same time with multiple short blasts of compressed air or pressurized can solvent but without the carburetor being removed from the engine or taken a part. The same principles can easily be applied to all type carburetors for either a two or four-stroke engine.