A multi-link piston crank mechanism includes a crank pin bearing portion including a crank pin bearing central portion that is disposed at a center thereof in an axial direction of a crank shaft. The crank pin bearing central portion at a portion positioned on the first end side of the lower link is thicker in a radial direction of the crank pin than a portion positioned on the second end side of the lower link. The second control link end portion is thicker along a radial direction of the second through hole than the second upper link end portion along a radial direction of the first through hole.

The bearing apparatus 1 includes a crankshaft having multiple journals, main bearings supporting the crankshaft, and a bearing housing. The plurality of journals include a first journal with a lubricating oil passage and a second journal without a lubricating oil passage. The first and second journals are supported by first and second main bearings, respectively. The bearing housing is constituted by an Al-alloy upper housing and an Fe-alloy lower housing. The depth of the oil groove of the upper half bearing of the second main bearing at least in a 45 region is equal to or smaller than a half of the depth of the oil groove of the upper half bearing of the first main bearing in the 45 region.

A bearing device includes a crankshaft having a plurality of journal portions, main bearings for supporting the crankshaft, and a bearing housing. The plurality of journal portions includes a first journal portion with a lubricating oil passage and a second journal portion without the lubricating oil passage. The first and second journal portions are supported by the first and second main bearings. The bearing housing includes an upper-side housing and a lower-side housing. A length of a crush relief of at least an upper-side halved bearing of the second main bearing is larger than a length of the crush relief of each of upper-side and lower-side halved bearings of the first main bearing.

An internal combustion engine that includes an oil baffle in the oil sump. The internal combustion engine may include a crankcase comprising an oil sump containing an oil reservoir, a crankshaft, and an oil baffle positioned within the oil sump. The crankshaft may be a vertical crankshaft and a first balance shaft may extend upward from the oil baffle. The crankshaft may be positioned within the oil baffle and a drivetrain may, also optionally, be positioned in the oil baffle. The internal combustion engine may be configured such that the oil reservoir has a first oil level when the internal combustion engine is off and a second oil level when the internal combustion engine is running at normal operating conditions. The first oil level is above a floor of the oil baffle. The second oil level may, also, be above the floor of the oil baffle.

A substantially tubular supply line (2, 11) of a main oil gallery (1, 10) for distributing lubricating or cooling oil to bearing points of a crankshaft of an internal combustion engine. The supply line (2, 11) has at least one inflow opening (3, 5, 6, 13) arranged on the supply line (2, 11) and feed lines (4, 12) having feed line openings (7.1, 7.2) on the supply line (2, 11) for feeding the lubricating or cooling oil to the bearing points of the crankshaft in the crankcase. The inflow opening (3, 5, 6, 7.1, 7.2, 13) is formed in a flow-favorable manner and may define a funnel shape.

An engine lubrication structure supplies oil from an oil pump to individual components of an engine in which a balancer shaft is disposed parallel with a crank shaft in a crank case, the engine includes a turbocharger which compresses intake air using exhaust gas of the engine; a main gallery which supplies oil to a bearing of the crank shaft and a bearing of the balancer shaft and a sub-gallery which supplies, to individual components of the engine, oil that has been supplied to the bearing of the balancer shaft are provided in the crank case; and an oil passage which supplies oil to the turbocharger is connected to the sub-gallery.

A bearing device includes a crankshaft having a plurality of journal portions, main bearings for supporting the crankshaft, and a bearing housing. The plurality of journal portions includes a first journal portion with a lubricating oil passage and a second journal portion without the lubricating oil passage. The first and second journal portions are supported by the first and second main bearings. The bearing housing includes an upper-side housing and a lower-side housing. A length of a crush relief of at least an upper-side halved bearing of the second main bearing is larger than a length of the crush relief of each of upper-side and lower-side halved bearings of the first main bearing.

An internal combustion engine that includes an oil baffle in the oil sump. The internal combustion engine may include a crankcase comprising an oil sump containing an oil reservoir, a crankshaft, and an oil baffle positioned within the oil sump. The crankshaft may be a vertical crankshaft and a first balance shaft may extend upward from the oil baffle. The crankshaft may be positioned within the oil baffle and a drivetrain may, also optionally, be positioned in the oil baffle. The internal combustion engine may be configured such that the oil reservoir has a first oil level when the internal combustion engine is off and a second oil level when the internal combustion engine is running at normal operating conditions. The first oil level is above a floor of the oil baffle. The second oil level may, also, be above the floor of the oil baffle.

A four-stroke engine lubrication system comprises: an engine body in which a crank shaft chamber and an air valve distribution chamber are arranged; a cylinder head cover fixed onto the engine and communicated with the atmosphere; and an oil storage tank which is configured to store lubricating oil, arranged on the engine body, located at one side of a cam, and provided with an oil mist generation device therein, wherein an oil outlet passage of the oil mist generation device communicates the oil storage tank with the crank shaft chamber via an oil outlet pipe; the crank shaft chamber is communicated with the air valve distribution chamber via a check valve; the air valve distribution chamber is communicated with the oil storage tank via a pipe; the air valve distribution chamber is communicated with the cylinder head cover; and the cylinder head cover is communicated with the oil storage tank.

A crankshaft has a rotational axis, about which the crankshaft can be rotated, and a crankpin journal for mounting a connecting rod eye of a connecting rod. A groove runs in the circumferential direction of the crankpin journal and is provided for the supply of lubricating oil in an outer surface of the crankpin journal. The groove extends only over a defined part length of the circumference of the crankpin journal. A crank arrangement includes a crankshaft of this type and a bearing shell which engages around the crankpin journal.