A transmission includes a case, a clutch pack, a piston. The case defines a bore that transitions along a step from a first to a second diameter. The piston is disposed within the bore. The piston has first and second seals that engage the case along the first and second diameters, respectively. The piston defines a chamber that is encompassed by the piston, the case, the first seal, and the second seal. The piston is configured to engage a clutch pack when hydraulic fluid is channeled into the chamber.

A piston of an internal combustion engine is disclosed. The piston includes a piston head with a piston bowl, a ring part and an annular cooling channel arranged between the ring part and the piston bowl. A closure element is provided to close the cooling channel in a direction away from the piston bowl. At least one guiding element is arranged in the cooling channel. The at least one guiding element provides a lug facing in a direction of an inner cooling channel wall and disposed at least partially circumferentially. The lug of the at least one guiding element is structured and arranged to direct cooling oil present in the cooling channel towards an upper region of the inner cooling channel wall relative to the closure element to facilitate cooling the upper region.

A piston of an internal combustion engine is disclosed. The piston includes a piston head with a piston bowl, a ring part and an annular cooling channel arranged between the ring part and the piston bowl. A closure element is provided to close the cooling channel in a direction away from the piston bowl. At least one guiding element is arranged in the cooling channel. The at least one guiding element provides a lug facing in a direction of an inner cooling channel wall and disposed at least partially circumferentially. The lug of the at least one guiding element is structured and arranged to direct cooling oil present in the cooling channel towards an upper region of the inner cooling channel wall relative to the closure element to facilitate cooling the upper region.

The present invention discloses a piston for an engine. The piston comprises a piston body; wherein, a top land, a first compression ring groove, a second land, a second compression ring groove, a third land, an oil ring groove are disposed in turn on the periphery of the piston body from top to bottom; the ratio of the depth of the first compression ring groove to the depth of the second compression ring groove is less than or equal to 1.0; at least one of annular expansion grooves are disposed on the periphery of the second land and/or the third land, to reduce the intra-cylinder carbon deposition and the hydrocarbon emissions in the exhaust gas emissions of the engine and thus improve the engine efficiency and the overall performance of the engine.

The present invention discloses an energy-saving and emission-reducing multistage throttling expansion method for engine. In a crevice passage disposed between the combustion chamber and the crankcase, a multistage throttling is disposed for converting pressure energy of the high-pressure blow-by gas into kinetic energy and momentum, and a multistage expansion is disposed for expanding and dissipating the incoming kinetic energy and momentum of the high-velocity blow-by gas into heat, so that to realize the multistage throttling and expansion method, reduce the leaking of the unburned fuel-air mixture and the burned gas, the hydrocarbon emissions hidden in the intra-cylinder carbon deposition and exhaust gas emissions of the engine, and also improve the engine efficiency and the overall performance of the engine.

A piston for an internal combustion engine includes a piston crown and a piston skirt, and an oil gallery formed between the piston crown and the piston skirt. A gallery inlet to the oil gallery, and a plurality of gallery drain outlets are formed in the piston skirt. The gallery drain outlets have, circumferentially around the piston center axis, a non-axisymmetric arrangement in a distribution biased to an anti-thrust side of the piston.

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.

A piston arrangement comprises a circumferential piston groove that can accommodate a seal for sealing between the piston and the cylinder bore when the piston moves in a reciprocal movement. The piston arrangement comprises a first fluid flow passage, defined at least in part by the piston body that fluidly connects the forward side of the cylinder bore with a space within the piston groove underneath the seal and a second fluid flow passage, defined in part by the piston body, which fluidly connects the rear side of the cylinder bore with the space within the piston groove underneath the seal. The two fluid flow passages allow a controlled fluid flow around the piston seal and comprise a channel provided in a lateral wall of the piston groove or an orifice provided in the piston body.

A piston arrangement comprises a circumferential piston groove that can accommodate a seal for sealing between the piston and the cylinder bore when the piston moves in a reciprocal movement. The piston arrangement comprises a first fluid flow passage, defined at least in part by the piston body that fluidly connects the forward side of the cylinder bore with a space within the piston groove underneath the seal and a second fluid flow passage, defined in part by the piston body, which fluidly connects the rear side of the cylinder bore with the space within the piston groove underneath the seal. The two fluid flow passages allow a controlled fluid flow around the piston seal and comprise a channel provided in a lateral wall of the piston groove or an orifice provided in the piston body.

A piston for an internal combustion engine is provided. The piston includes a piston body including an upper combustion surface, an annular side wall with a ring belt region, and a cooling gallery located within the piston body having a fluid inlet. A piston ring is located in a ring groove around the ring belt region and an alignment pin is secured in a hole in the piston side wall to restrict circumferential displacement of the piston ring. The piston body further includes a boss within the cooling gallery into which the hole and the alignment pin extend. The boss projects into the cooling gallery opposite the fluid inlet and is shaped to provide a flow splitter surface configured to divide cooling fluid flowing through the fluid inlet during use into first and second fluid flows and to direct the first and second fluid flows in opposite directions around the cooling gallery.