The present invention addresses the problem of providing a piston ring covered with a DLC coating that has excellent wear resistance and shows a low attacking property on a cylinder bore sliding surface. The problem is solved by a piston ring which is used in the presence of an engine lubricating oil and includes a DLC coating on an outer peripheral sliding surface. The DLC coating has an sp.sup.2 component ratio of 0.5 to 0.85 as determined from a TEM-EELS spectrum obtained by a combination of a transmission electron microscope (TEM) and electron energy loss spectroscopy (EELS), as well as a coating hardness of 12 GPa to 26 GPa and a Young's modulus of 250 GPa or less as measured by a nanoindentation method.

A piston ring includes a first ring portion which is fitted onto an outer circumferential portion of a piston and which is capable of sliding relative to an inner wall surface of a cylinder, and a second ring portion which is fitted onto the outer circumferential portion of the piston, arranged side-by-side with the first ring portion in the axial direction, and which is capable of sliding relative to the inner wall surface of the cylinder. The second ring portion is fitted onto the outer circumferential portion of the piston in such a way as to be positioned on a side opposite to a compression chamber inside the cylinder, relative to the first ring portion, and has a greater hardness than the first ring portion has.

A piston ring structure includes a piston ring having an opening, and at least one positioning clip mounted on the opening of the piston ring. The at least one positioning clip is provided with two insertion slots corresponding to two sides of the opening. The at least one positioning clip is provided with a spacing rib located between the insertion slots. Each of the insertion slots of the at least one positioning clip are mounted on each of the two sides of the opening of the piston ring, with each of the two sides of the opening being inserted into each of the insertion slots of the at least one positioning clip.

A piston ring structure includes a piston ring having an opening, and at least one positioning clip mounted on the opening of the piston ring. The at least one positioning clip is provided with two insertion slots corresponding to two sides of the opening. The at least one positioning clip is provided with a spacing rib located between the insertion slots. Each of the insertion slots of the at least one positioning clip are mounted on each of the two sides of the opening of the piston ring, with each of the two sides of the opening being inserted into each of the insertion slots of the at least one positioning clip.

The invention relates to a hydraulic tool mount having a bore into which a sealing piston is inserted, wherein the sealing piston comprises a pin, a seal and a head which are arranged one behind the other in an axial direction (A) and thus form a stack, wherein the seal comprises a circumferential sealing lip for abutment and sealing against an inner wall of the bore in order to achieve a first sealing effect, and the bore comprises a sealing seat which, when the sealing piston is inserted, forms a stop for the head in axial direction (A), so that, in an end position of the sealing piston, the head abuts the sealing seat and thereby closes the bore in order to achieve a second sealing effect. The invention further relates to a corresponding sealing piston.

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.

A disposable dual-action reciprocating pump part includes a piston and a cylinder, and multiple silicone O-rings. The piston is configured to move bi-directionally inside the cylinder. The multiple silicone O-rings are configured to seal the piston against the cylinder.

A disposable dual-action reciprocating pump part includes a piston and a cylinder, and multiple silicone O-rings. The piston is configured to move bi-directionally inside the cylinder. The multiple silicone O-rings are configured to seal the piston against the cylinder.

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 invention discloses a compressor configured to compress gas. The compressor includes: a cylinder part; a piston disposed in the cylinder part to form in the cylinder part a compression chamber in which the gas is compressed, the piston being configured to compress the gas in the compression chamber; a first sealing part located adjacent to the compression chamber and attached to an outer circumference of the piston, and formed mainly containing at least one type of component that is selected from a group of polyetheretherketone, polyimide, and polybenzimidazole; and a second sealing part located more separated from the compression chamber than the first sealing part is from the compression chamber and attached to the outer circumference of the piston, the second sealing part having a hardness equal to or smaller than that of the first sealing part.