The present disclosure is a combination of a cylinder and a piston ring, the combination including a cylinder of an internal combustion engine and a piston ring sliding on an inner peripheral surface of the cylinder. The piston ring has an outer peripheral surface sliding on the inner peripheral surface of the cylinder, and the outer peripheral surface is formed of a substantially hydrogen-free amorphous carbon coating. The Vickers hardness Hd of the amorphous carbon coating and the Vickers hardness Hb of the inner peripheral surface of the cylinder satisfy Hd+Hb≤2500 HV. The ratio ID/IG of the peak intensity of the D band to the peak intensity of the G band in a Raman spectrum obtained by measuring the amorphous carbon coating by Raman spectroscopy is 0.60 or more and 1.33 or less.

This shock absorber includes a piston main body and a piston band. The piston main body has, at an outer peripheral portion thereof, a stepped portion including a large-diameter surface portion, a stepped surface portion and a small-diameter surface portion. The piston band has, at an outer peripheral portion thereof, a large diameter portion, a medium diameter portion formed so as to have a smaller diameter than the large diameter portion, and a small diameter portion formed between the large diameter portion and the medium diameter portion so as to have a smaller diameter than the medium diameter portion, in a state before being disposed in a cylinder. At one end on the side close to a tip portion of a piston rod, an inner peripheral surface is inclined toward the piston main body side from the large-diameter surface portion to a small-diameter surface portion of the stepped portion.

A piston ring is used for a reciprocating compressor. In the piston ring, polytetrafluoroethylene and polyetheretherketone or polyimide account for 50% or more by mass in total. The piston ring does not contain polyphenylene sulfide. The piston ring has a tensile strength within a range of more than 15 MPa and less than 100 MPa.

A piston ring is used for a reciprocating compressor. In the piston ring, polytetrafluoroethylene and polyetheretherketone or polyimide account for 50% or more by mass in total. The piston ring does not contain polyphenylene sulfide. The piston ring has a tensile strength within a range of more than 15 MPa and less than 100 MPa.

An internal combustion engine includes a hollow cylinder, a piston within the hollow cylinder, and a cylinder head. A base valve assembly at a base of the hollow cylinder permits or restricts fluid flow from an intake manifold into a sub-chamber below the piston. The piston includes at least one intake port connecting a combustion chamber above the piston with the sub-chamber, and a transfer valve that opens and closes the at least one intake port. When the transfer valve opens the at least one intake port, fluid is permitted to flow from the sub-chamber to the combustion chamber. The internal combustion engine operates according to a four-stroke piston cycle, wherein multiple intake stages are provided. The intake stages may include intake of air into the sub-chamber during a compression stroke, transfer of air from the sub-chamber to the combustion chamber during a power stroke, intake of air-fuel mixture into the sub-chamber during an exhaust stroke, and transfer of air-fuel mixture from the sub-chamber to the combustion chamber during an intake stroke.

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.

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 sliding element may include a base material having an annular external surface upon which a bonding layer and a sliding layer are sequentially deposited. The sliding layer may be composed of hard amorphous carbon of a combined matrix with sp3/sp2 bonds. The sliding layer may include a plurality of nanoparticles of graphite incorporated within the combined matrix of sp3/sp2.

A sliding element may include a base material having an annular external surface upon which a bonding layer and a sliding layer are sequentially deposited. The sliding layer may be composed of hard amorphous carbon of a combined matrix with sp3/sp2 bonds. The sliding layer may include a plurality of nanoparticles of graphite incorporated within the combined matrix of sp3/sp2.

A seal structure includes a mounting groove disposed in a first member and a packing unit housed in the mounting groove. The packing unit includes an inner circumferential mounting section and an outer circumferential sliding section. Both side surfaces of the packing unit are conical surfaces which are inclined such that their diameters gradually increase in a direction from the mounting section toward the sliding section and which are inclined in mutually opposite directions. The thickness of the packing unit increases in a gradual manner in the direction from the mounting section toward the sliding section, the thickness in the mounting section is the smallest, and the thickness in the sliding section is the largest.