A cylindrical sleeve for an internal combustion engine is disclosed. The cylindrical sleeve includes a hollow cylindrical sleeve body, extending along an axial direction, with an inner peripheral side that has, along the axial direction, a first axial portion and a second axial portion. The inner peripheral side in the first axial portion is either cylindrical or opens at a first opening angle towards the second axial portion. The second axial portion opens at a second opening angle away from the first axial portion that is greater than the first opening angle. A first surface roughness of the inner peripheral side in the first axial portion is greater than a second surface roughness in the second axial portion.

An engine includes a cylinder block including a cylinder hole, a crank shaft as an offset crank, and a connecting rod that connects the piston and the crank shaft. An inclined surface is provided on an entire circumference of a crank-shaft-side opening edge of one end of the cylinder hole. When viewed in the axial direction of the crank shaft, a boundary line between the inclined surface and the cylinder hole extends towards the other end of the cylinder hole as it extends toward an offset side on which the crank shaft is offset from the center axis of the cylinder hole. The offset crank engine has the entire circumference of the crank-shaft-side opening edge of the cylinder hole chamfered without any bad influence on the sliding surface and posture of the piston to avoid interference between the crank-shaft-side opening edge of the cylinder hole and the connecting rod.

An engine includes a cylinder block including a cylinder hole, a crank shaft as an offset crank, and a connecting rod that connects the piston and the crank shaft. An inclined surface is provided on an entire circumference of a crank-shaft-side opening edge of one end of the cylinder hole. When viewed in the axial direction of the crank shaft, a boundary line between the inclined surface and the cylinder hole extends towards the other end of the cylinder hole as it extends toward an offset side on which the crank shaft is offset from the center axis of the cylinder hole. The offset crank engine has the entire circumference of the crank-shaft-side opening edge of the cylinder hole chamfered without any bad influence on the sliding surface and posture of the piston to avoid interference between the crank-shaft-side opening edge of the cylinder hole and the connecting rod.

A photonic reflector device includes a first layer, a second layer, and a third layer. The first layer, which functions as a retro-reflector, is formed of a first material contacting a second material and having a non-planar interface therebetween. The second layer, which functions as a photonic crystal, includes third and fourth materials that have different refractive indices from one another and are configured such that the second layer has a periodic optical potential along at least one dimension. The third layer, which functions as a Lambertian scatterer, includes a plurality of inclusions in a first matrix material. In combination, the layers may be optimized to synergistically reflect targeted wavelengths and/or polarizations of light.

A cylinder liner for an internal combustion engine may include a hollow-cylindrical liner body, which may have an inner circumferential surface including a first axial portion and a second axial portion. The first axial portion may open at a first opening angle towards the second axial portion. The second axial portion may open at a second opening angle away from the first axial portion. The second opening angle may be greater than the first opening angle. A first surface roughness in the first axial portion may be greater than a second surface roughness in the second axial portion. A plateau aspect in the second axial portion, which may be defined as R3p=Rvk/(Rpk+Rk), may be 0.2 to 1.6. A texture height in the second axial portion, which may be defined as R3k=Rpk+Rk+Rvk, may be 0.4 μm or less.

A photonic reflector device includes a first layer, a second layer, and a third layer. The first layer, which functions as a retro-reflector, is formed of a first material contacting a second material and having a non-planar interface therebetween. The second layer, which functions as a photonic crystal, includes third and fourth materials that have different refractive indices from one another and are configured such that the second layer has a periodic optical potential along at least one dimension. The third layer, which functions as a Lambertian scatterer, includes a plurality of inclusions in a first matrix material. In combination, the layers may be optimized to synergistically reflect targeted wavelengths and/or polarizations of light.

A piston engine may include a clearance gap between a piston assembly and a cylinder. The piston may be configured to translate in a bore of the cylinder. The clearance gap between the piston assembly and the bore may be actively or passively controlled. A control system may provide one or more adjustments based on, for example, a detected temperature, pressure, flow rate, work metric, and/or other indicator. The adjustments may include, for example, adjusting a cylinder liner, adjusting a flow through a bearing element, adjusting a coolant flow, adjusting a heat pipe property, and/or other adjustments. One or more auxiliary systems may be used to provide the adjustments.

A piston engine may include a clearance gap between a piston assembly and a cylinder. The piston may be configured to translate in a bore of the cylinder. The clearance gap between the piston assembly and the bore may be actively or passively controlled. A control system may provide one or more adjustments based on, for example, a detected temperature, pressure, flow rate, work metric, and/or other indicator. The adjustments may include, for example, adjusting a cylinder liner, adjusting a flow through a bearing element, adjusting a coolant flow, adjusting a heat pipe property, and/or other adjustments. One or more auxiliary systems may be used to provide the adjustments.

A sliding mechanism of the present invention includes a cylinder bore having a thermally sprayed iron-based coating and includes a piston with a piston ring covered with a hard coating composed mainly of carbon. The thermally sprayed coating has diamond abrasive grains. An area ratio of the diamond abrasive grains to a surface of the thermally sprayed coating is 0.3 to 1.8%, which enables suppressing wear of the piston ring having the hard coating composed mainly of carbon.

An internal combustion engine with at least one cylinder having a cylinder barrel that forms a guide for a piston associated with the cylinder. The cylinder barrel is only partially formed by a cylinder wall of a crankcase or of a cylinder liner fastened to the crankcase. The cylinder barrel, in a central region as seen in the cylinder axial direction, is formed by the cylinder wall. The cylinder wall, in an upper region of the cylinder barrel adjoining the central region and/or in a lower region adjoining the central region, has an encompassing recess into which is inserted a one-piece or multi-piece annular sliding element, the radially inner wall of which forms a part of the cylinder barrel.