Systems and methods for forming a plurality of valleys on an inner circumferential surface of a cylinder liner for uniform oil film thickness are disclosed. In one aspect, an internal combustion engine includes a piston; and a cylinder liner surrounding the piston, wherein the cylinder liner has a plurality of valleys on an inner circumferential surface of the cylinder liner, and wherein the plurality of valleys are formed to a frequency of 7 to 14 valleys per millimeter (mm) having a depth of at least 1 micrometer (μm).

The present invention addresses the problem of providing a cylinder liner or a cylinder bore, which can reduce not only friction on a sliding surface but also oil consumption. In a piston sliding direction of the cylinder bore, grooves of a second sliding region positioned on the side of crankcase have a higher groove area ratio at a depth of 0.3 μm than grooves of a first sliding region positioned on the side of combustion chamber, and the groove area ratio is in a specific range, whereby friction and oil consumption can be reduced.

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.

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.

Provided is a cylinder liner which can reduce the friction of the sliding surface from conventional levels and improve fuel efficiency without increasing oil consumption from conventional levels.

When the inner circumferential surface of a cylinder liner or cylinder bore used in an internal combustion engine has a first sliding region, a second sliding region, and a third sliding region, and when respective surface roughness Rvk is from 0.05 μm to 0.3 μm, from 0.4 μm to 1.5 μm, and from 0.15 μm to 0.7 μm, a friction can be reduced while maintaining oil consumption.

Provided is a cylinder liner which can reduce the friction of the sliding surface from conventional levels and improve fuel efficiency without increasing oil consumption from conventional levels.

When the inner circumferential surface of a cylinder liner or cylinder bore used in an internal combustion engine has a first sliding region, a second sliding region, and a third sliding region, and when respective surface roughness Rvk is from 0.05 μm to 0.3 μm, from 0.4 μm to 1.5 μm, and from 0.15 μm to 0.7 μm, a friction can be reduced while maintaining oil consumption.

The present invention addresses the problem of providing a cylinder liner or a cylinder bore, which can reduce not only friction on a sliding surface but also oil consumption. In a piston sliding direction of the cylinder bore, grooves of a second sliding region positioned on the side of crankcase have a higher groove area ratio at a depth of 0.3 μm than grooves of a first sliding region positioned on the side of combustion chamber, and the groove area ratio is in a specific range, whereby friction and oil consumption can be reduced.

The present invention addresses the problem of providing a cylinder liner or a cylinder bore, which can reduce not only friction on a sliding surface but also oil consumption. In a piston sliding direction of the cylinder bore, grooves of a second sliding region positioned on the side of crankcase have a higher groove area ratio at a depth of 0.3 μm than grooves of a first sliding region positioned on the side of combustion chamber, and the groove area ratio is in a specific range, whereby friction and oil consumption can be reduced.

Provided is a V engine which uses common cylinder heads, and permits favorable arrangement of oil passages so as to accommodate various oil regulating features that are required to operate valve property varying mechanisms. Each end of each cylinder head is formed with a plurality of distribution oil passages opening out at an upper surface of the cylinder head for supplying oil pressure from a main gallery to a valve actuating mechanism. A pair of oil passage connecting members internally defining mutually different connecting oil passages are attached to the upper surfaces of the corresponding end parts of the respective cylinder heads.

Provided is a V engine which uses common cylinder heads, and permits favorable arrangement of oil passages so as to accommodate various oil regulating features that are required to operate valve property varying mechanisms. Each end of each cylinder head is formed with a plurality of distribution oil passages opening out at an upper surface of the cylinder head for supplying oil pressure from a main gallery to a valve actuating mechanism. A pair of oil passage connecting members internally defining mutually different connecting oil passages are attached to the upper surfaces of the corresponding end parts of the respective cylinder heads.