A hydraulic tensioner includes a housing defining a cavity configured to receive a fluid from a pressurized fluid source. The hydraulic tensioner also includes a piston disposed within the cavity and configured for movement between a retracted position and an extended position based on a pressure of the fluid. Additionally, the hydraulic tensioner includes a sleeve disposed within the cavity and having an inner surface and an outer surface spaced from the inner surface, the inner surface defining an interior aperture for receiving the piston. Moreover, the sleeve has a thickness of 2 mm or less between the inner surface and the outer surface.

The present invention relates to a tribological system (1; 2) comprising a first body (102; 105) and a second body (101; 107), which each form a component of an internal combustion engine (100), in particular a piston (102), a piston ring (105) or a cylinder (101, 107), and the surfaces (112, 108, 113) of which have a first and a second material area (11, 12) which come into contact with each other at least in some regions during operation and form a tribological contact, wherein the first and/or the second material area (11, 12) is formed as a layer on the basis of chromium oxide or aluminum chromium oxide. The invention also relates to an internal combustion engine (100) having such a system (1; 2).

The present invention relates to a tribological system (1; 2) comprising a first body (102; 105) and a second body (101; 107), which each form a component of an internal combustion engine (100), in particular a piston (102), a piston ring (105) or a cylinder (101, 107), and the surfaces (112, 108, 113) of which have a first and a second material area (11, 12) which come into contact with each other at least in some regions during operation and form a tribological contact, wherein the first and/or the second material area (11, 12) is formed as a layer on the basis of chromium oxide or aluminum chromium oxide. The invention also relates to an internal combustion engine (100) having such a system (1; 2).

A damper includes a piston provided with a rod, and a cylinder storing the piston, and generates a braking force by a movement or relative movement of the piston. The cylinder is provided with width-side wall portions and thickness-side wall portions, and a shape in a cross section of the cylinder in a direction orthogonal to a moving direction of the piston is flat. The cylinder has a connection portion on an open side thereof, and the connection portion bridges the width-side wall portions.

A damper includes a piston provided with a rod, and a cylinder storing the piston, and generates a braking force by a movement or relative movement of the piston. The cylinder is provided with width-side wall portions and thickness-side wall portions, and a shape in a cross section of the cylinder in a direction orthogonal to a moving direction of the piston is flat. The cylinder has a connection portion on an open side thereof, and the connection portion bridges the width-side wall portions.

The invention relates to a cylinder bore and a method. The cylinder bore is configured to receive a piston for reciprocating movement therein and has a pressure side and a counter-pressure side. The cylinder bore includes a bore surface having a first roughness value in a first longitudinal region on the pressure side and a second roughness value different from the first roughness value in the first longitudinal region on the counter-pressure side.

The invention relates to a cylinder bore and a method. The cylinder bore is configured to receive a piston for reciprocating movement therein and has a pressure side and a counter-pressure side. The cylinder bore includes a bore surface having a first roughness value in a first longitudinal region on the pressure side and a second roughness value different from the first roughness value in the first longitudinal region on the counter-pressure side.

Methods and systems are provided for a bore. In one example, a system includes a bore portion for receiving a reciprocating piston, the bore portion having first and second ends between which the piston travels in an axial direction. The bore portion comprises a plurality of recesses, axially spaced apart, and formed in a piston facing surface of the bore portion at a plurality of axial positions, with at least one recess being provided at each axial position. Widths of the plurality of recesses decrease in the axial direction away from a mid-stroke position toward the first and second ends, and depths of the plurality of recesses increase in the axial direction away from the mid-stroke position toward the first and second ends.

Methods and systems are provided for a bore. In one example, a system includes a bore portion for receiving a reciprocating piston, the bore portion having first and second ends between which the piston travels in an axial direction. The bore portion comprises a plurality of recesses, axially spaced apart, and formed in a piston facing surface of the bore portion at a plurality of axial positions, with at least one recess being provided at each axial position. Widths of the plurality of recesses decrease in the axial direction away from a mid-stroke position toward the first and second ends, and depths of the plurality of recesses increase in the axial direction away from the mid-stroke position toward the first and second ends.

Provided is a cast-iron cylindrical member having projections (P) formed integrally with a casted surface (an outer peripheral surface), and a composite structure including the cast-iron cylindrical member and an outer periphery-side member. The cast-iron cylindrical member satisfies: (A) 0.50 mm>a height (H) of the projections (P)0.20 mm; (B) 180a total number (N) of the projections (P) per cm.sup.2 of the outer peripheral surface61; (C) the projections (P) include a projection (Pn) having a constricted shape; (D) a ratio (NP) of the projections (Pn) to the projections (P)50%; (E) a bonding strength index (S) expressed by: S=H.sup.2NNP is equal to or larger than 310; and (F1) a bonding strength F(Al) obtained when the outer peripheral surface of the cast-iron cylindrical member is cast-in inserted with an aluminum alloy exceeds a boundary bonding strength (Fb) expressed by: Fb=1.325H.sup.2N0.75.