A piston ring set for internal combustion (IC) engine is provided. The IC engine includes a cylinder having a liner and a finish on the liner. A piston having a crown and a set of grooves is disposed in the cylinder. A set of piston rings is disposed in the set of grooves. The piston rings are disposed in order from closest to the crown and include at least a first compression ring having free ends defining a first end gap, a second compression ring having free ends defining a second end gap. A nominal value of the first end gap of the first compression ring is greater than a nominal value of the second end gap of the second compression ring.

In an engine piston assembly of the present invention, a piston structure, together with a piston ring set matched to the piston structure and an inner wall of a cylinder bore body, forms a crevice passage having at least two annular expansion chambers and also having a function of multistage throttling and expansion. The engine piston assembly of the present invention can not only greatly and effectively reduce the intra-cylinder carbon deposition and the hydrocarbon emissions in the exhaust gas emissions of the engine, but also significantly improve the engine efficiency and the overall performance of the engine, so that the present invention is suitable for wide applications.

In an engine piston assembly of the present invention, a piston structure, together with a piston ring set matched to the piston structure and an inner wall of a cylinder bore body, forms a crevice passage having at least two annular expansion chambers and also having a function of multistage throttling and expansion. The engine piston assembly of the present invention can not only greatly and effectively reduce the intra-cylinder carbon deposition and the hydrocarbon emissions in the exhaust gas emissions of the engine, but also significantly improve the engine efficiency and the overall performance of the engine, so that the present invention is suitable for wide applications.

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 novel cleaning container is disclosed for backflushing and hence clean an espresso machine. The container may include a body having a top, an opposing bottom, and an interior cavity for holding water, detergent, and/or other cleaning fluid. A piston is slidably disposed within the interior cavity between up and down positions, wherein the piston and an opening of the body at the top define a variable volume for cleaning the machine. A spring is seated firmly within the body underneath the piston for biasing the piston to the up position. A stopper disposed about the top of the piston limits the motion of the piston at the top of the body. One or more grooves within the body are in fluid communication with one or more outlets to permit fluid to exit the body during cleaning. The body may be transparent or translucent.

A pump assembly, fluid machinery, and a heat exchange device. The pump assembly includes: a lower flange; a lower friction-reducing ring; a cylinder, the lower friction-reducing ring being disposed inside the cylinder, and the lower flange being disposed below the cylinder; and a piston assembly arranged inside the cylinder and includes a piston sleeve and a piston slidably arranged inside the piston sleeve. The lower friction-reducing ring has a central hole. A position-limiting protrusion is disposed on a surface of the piston sleeve, which faces the lower flange. The limiting protrusion extends into the central hole of the lower friction-reducing ring, fits and is limited by the lower flange.

A pump assembly, fluid machinery, and a heat exchange device. The pump assembly includes: a lower flange; a lower friction-reducing ring; a cylinder, the lower friction-reducing ring being disposed inside the cylinder, and the lower flange being disposed below the cylinder; and a piston assembly arranged inside the cylinder and includes a piston sleeve and a piston slidably arranged inside the piston sleeve. The lower friction-reducing ring has a central hole. A position-limiting protrusion is disposed on a surface of the piston sleeve, which faces the lower flange. The limiting protrusion extends into the central hole of the lower friction-reducing ring, fits and is limited by the lower flange.

Provided are an oil ring for an internal combustion engine and a piston assembly including the same, in which the oil ring for an internal combustion engine includes: a compression portion protruding from an upper portion of a body, in close contact with a cylinder inner wall and effectively limiting explosive gas generated in a combustion chamber; a scraper portion protruding from a lower portion of the body, in close contact with the cylinder inner wall and including a nose scraping off oil oversupplied to cylinder inner wall; and an oil suction portion being a space formed between the compression portion and the scraper portion to collect and discharge the oil oversupplied to cylinder inner wall, thereby reducing leakage of high-temperature and high-pressure gas generated in the combustion chamber, and preventing incomplete combustion caused by oil leaked into the combustion chamber.

Piston ring arrangement (40) with a piston ring (50) encircling a main axis (X), the piston ring (50) having a sealing surface (58) directed radially outward and a contact surface (55) directed radially outward, the sealing surface (58) being radially outside of the contact surface (55). To improve the service life of piston rings for reciprocating compressors, the piston ring arrangement (40) has a retaining ring (70) encircling the main axis (X) with a retaining surface (72) directed radially inward, the piston ring (50) and the retaining ring (70) being situated such that the retaining surface (72) and the contact surface (55) are adjacent in the radial direction.