An annular seal for sealing an opening in a pump housing surrounding a piston rod includes a primary sealing portion with an inner surface adjacent to the piston rod and an outer surface adjacent to the pump housing. An initial sealing portion features an inner wall and an outer wall so that an annular space is defined therebetween. A top wall extends between the inner and outer walls. A coil spring is positioned within the annular space of the initial sealing portion and urges the inner wall into engagement with the piston rod and the outer wall into engagement with the pump housing.

A piston assembly for an internal combustion engine includes a cylinder bore and a piston having exactly two ring grooves, a scraper ring positioned in the upper ring groove, and an oil control ring positioned in the lower ring groove. A constant twist occurs in the scraper ring about a rotational center of the cross-section, the constant twist occurring at each cross-sectional location of the scraper ring about the circumference of the ring and between adjacent free ends of the ring. The oil control ring can be of a multi-segmented U-flex design, with a coil spring mounted in a channel thereof. The combination of the two rings leads to improved sealing and oil control so that the piston can be manufactured with only two rings, thus reducing overall weight and cost.

The present disclosure provides a sealing ring assembly having a sealing ring and a reinforcement, configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The sealing ring may be segmented, and a metal layer, wire, or other reinforcement may be affixed to the ring. The reinforcement is placed into tension against the sealing ring, which is correspondingly placed into compression. The composite structure of a relatively brittle sealing ring and reinforcement provides for reduced tensile loads in the sealing ring, thus extending life and reducing the likelihood of failure. The brittle portion of the sealing ring assembly may include a polymer or ceramic such as graphite, which is relatively less strong in tension than compression.

A combination of piston rings assembled to a piston includes a first compression ring, a second compression ring, a third compression ring and an oil ring. When an axial width of the first compression ring is h1(1), an axial width of the second compression ring is h1(2), an axial width of the third compression ring is h1(3) and an axial width of the oil ring is h1(4), h1(1)≥h1(2) and h1(1)≥h1(3), and when h1(TOTAL)=h1(1)+h1(2)+h1(3)+h1(4), h1(TOTAL)≥3.1 mm.

A combination of piston rings assembled to a piston includes a first compression ring, a second compression ring, a third compression ring and an oil ring. When an axial width of the first compression ring is h1(1), an axial width of the second compression ring is h1(2), an axial width of the third compression ring is h1(3) and an axial width of the oil ring is h1(4), h1(1)≥h1(2) and h1(1)≥h1(3), and when h1(TOTAL)=h1(1)+h1(2)+h1(3)+h1(4), h1(TOTAL)≥3.1 mm.

The present disclosure provides a sealing ring assembly having ring segments configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The sing segments are configured to move radially outward and wear during operation of the piston via the cylinder device. The ring segments include, for example, wedge-shaped features that engage with corresponding wedge recesses in the interfaces between ring segments. The sealing ring assembly may include a high-pressure boundary and a low-pressure boundary. As the sealing ring wears, the ring segments stay engaged with the interfaces, so that ring gaps do not form on the low pressure boundary.

The present disclosure provides a sealing ring assembly having ring segments configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The sing segments are configured to move radially outward and wear during operation of the piston via the cylinder device. The ring segments include, for example, wedge-shaped features that engage with corresponding wedge recesses in the interfaces between ring segments. The sealing ring assembly may include a high-pressure boundary and a low-pressure boundary. As the sealing ring wears, the ring segments stay engaged with the interfaces, so that ring gaps do not form on the low pressure boundary.

A multi-piece piston ring includes an upper scraper ring 10 comprising two flank surfaces, an outer scraping surface/edge, and an inner spring contact surface. A lower support ring 4 includes two flank surfaces, an outer spring contact surface, and a support ring inner surface. An expander spring/spiral spring 8, which, on an upper and lower side, is operational to abut against a respective lower flank surface of the upper scraper ring 10 and against the upper flank surface of the support ring 4. Scraper ring contact projections protruding upwards on an inner spring side, and support ring contact projections protruding downwards on an outer spring side, wherein the scraper ring contact projections are to each abut against the inner spring contact surface of the scraper ring 10, and support ring contact projections protruding downwards are to abut against the outer spring contact surface.

A multi-piece piston ring includes an upper scraper ring 10 comprising two flank surfaces, an outer scraping surface/edge, and an inner spring contact surface. A lower support ring 4 includes two flank surfaces, an outer spring contact surface, and a support ring inner surface. An expander spring/spiral spring 8, which, on an upper and lower side, is operational to abut against a respective lower flank surface of the upper scraper ring 10 and against the upper flank surface of the support ring 4. Scraper ring contact projections protruding upwards on an inner spring side, and support ring contact projections protruding downwards on an outer spring side, wherein the scraper ring contact projections are to each abut against the inner spring contact surface of the scraper ring 10, and support ring contact projections protruding downwards are to abut against the outer spring contact surface.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted therein. The piston may be configured to move in a first stroke that includes an expansion stroke portion and a non-expansion stroke portion. The engine may further include first and second piston rod portions extending from opposite faces of the piston. A recess in the piston rod portions may be configured to communicate gases between a combustion chamber and locations outside the cylinder. There may also be a chamber surrounding the first or second piston rod portion, the chamber configured to be supplied with gas and the chamber being isolated from the first combustion chamber and the second combustion chamber.