An engine is described having a crankcase, a liner and a head assembly. The crankcase is split along a plane defining a two part crankcase, where fluid passages are passing through only one of the crankcase portions, so as to not require crossing the split line. A connecting rod also includes a tapered end, and the piston has a complementary carrier receiving the connecting rod.

A bearing structure has a crankshaft rotatably supported by a crankshaft bearing part, formed of a cylinder block of an internal combustion engine and a first bearing cap, through a bearing metal, a second shaft rotatably supported by a second shaft bearing part formed of the first bearing cap and a second bearing cap, wherein the bearing metal has a bearing metal planar portion for rotatably supporting the crankshaft with an entire inner peripheral surface of the bearing metal, the inner peripheral surface at which the bearing metal planar portion is formed, a bearing metal oil groove portion formed with an oil groove formed to extend circumferentially in an inner peripheral surface of the bearing metal, the inner peripheral surface at which the bearing metal oil groove portion is formed, a first oil hole opening at the oil groove, and a second oil hole opening at the oil groove.

A lubrication device of an engine includes a crankshaft supported and rotatably mounted by a main bearing and disposed at one side of a cylinder block, wherein the crankshaft includes a first main journal and a second main journal at a center in an axial direction, the first main journal being disposed between a first pin journal and a second pin journal, the second main journal being disposed between the second pin journal and a third pin journal, and two oil holes formed at the first main journal, wherein one of the oil holes is extended so as to supply oil to the first pin journal, and another oil hole is extended so as to supply oil to the second pin journal.

Methods and systems are provided for an engine housing assembly. In one example, an engine housing assembly comprises an engine housing component, the housing component at least partially defining a first bore for receiving a first shaft and at least partially defining a second bore for receiving a second shaft; and a reinforcement member cast into the housing, the reinforcement member having a lower coefficient of thermal expansion than the housing component, wherein the reinforcement member at least partially surrounds the first and second bores. A method of manufacturing the engine housing assembly is also provided.

The present disclosure provides a lubrication system comprising: a pump having an inlet in fluid communication with a lubricant source and an outlet; a cooler having an inlet in fluid communication with the outlet of the pump and an outlet; a lubrication filter having an inlet in fluid communication with the outlet of the cooler and an outlet; a first delivery path in fluid communication with the outlet of the lubrication filter, the first delivery path being configured to deliver cooled, filtered lubricant to a bearing system of an engine; and a second delivery path in fluid communication with the outlet of the pump, the second delivery path being configured to deliver uncooled, unfiltered lubricant to piston cooling nozzles of the engine.

In an internal combustion engine, an oil return passage extending from a breather chamber can be formed without increasing the number of component parts and without increasing the size of the internal combustion engine. The internal combustion engine (1) comprises an engine block (30) defining a cylinder (2); a case member (19) fastened to a lower part of the engine block to define a crank chamber jointly with the engine block; a bearing member (50) fastened to the engine block in the crank chamber to rotatably support a crankshaft; a breather chamber (113) defined in the engine block; an inlet passage (112) formed in the engine block to communicate the crank chamber with the breather chamber; a connection pipe (114) communicating the breather chamber with an intake device; and an oil return passage (150) formed at least in the bearing member, and extending from a bottom part of the breather chamber to an oil return port (147) opening at an outer surface of the bearing member. The oil return port may be provided in a lower part of the bearing member.

A device lubricates a big-end bearing on a crankshaft of an internal combustion engine. The device includes a piston with a fluid channel and an outlet channel fluidically connected thereto, and a connecting rod. The connecting rod has a small connecting rod eye, a large connecting rod eye and a connecting channel. The small connecting rod eye is fluidically connected to the outlet channel. The connecting channel forms a fluidic connection between the small and large connecting rod eyes so that a cooling lubricant fluid can be supplied from the fluid channel to the large connecting rod eye via the outlet channel, the small connecting rod eye and the connecting channel. In this way, the big-end bearing can be lubricated by cooling oil from the fluid channel of the piston.

The present disclosure provides a lubrication system comprising: a pump having an inlet in fluid communication with a lubricant source and an outlet; a cooler having an inlet in fluid communication with the outlet of the pump and an outlet; a lubrication filter having an inlet in fluid communication with the outlet of the cooler and an outlet; a first delivery path in fluid communication with the outlet of the lubrication filter, the first delivery path being configured to deliver cooled, filtered lubricant to a bearing system of an engine; and a second delivery path in fluid communication with the outlet of the pump, the second delivery path being configured to deliver uncooled, unfiltered lubricant to piston cooling nozzles of the engine.

An internal combustion engine is provided, which includes an engine body provided with a cylinder and a piston reciprocatably accommodated in the cylinder, a crankshaft that converts reciprocating movement of the piston into rotational movement, and a bearing member pivotally supporting the crankshaft via lubricating oil. The crankshaft includes a crank journal pivotally supported by the bearing member, and a counterweight extending radially outward from an axial end part of the crank journal. The crank journal has a recess formed in a part thereof corresponding to the extended position of the counterweight, the recess being depressed radially inwardly. The recess is deeper at the axial end part of the crank journal than an axial center part.

A crankshaft bearing structure is provided, in which a crankshaft includes a first crank journal and a second crank journal, and a crank pin disposed therebetween. First upper-and-lower journal bearings and second upper-and-lower journal bearings are attached to the respective crank journals, and each upper bearing includes an oil hole connected to an oil passage to supply oil to between the crank journal and the journal bearings. An in-shaft oil passage is formed in the crankshaft to draw oil from an outer circumferential surface of the second crank journal to an outer circumferential surface of the crank pin. The second upper journal bearing has, on an inner circumferential surface thereof, a circumferential groove connected to the oil hole. The oil is supplied to between the first upper-and-lower journal bearings and the first crank journal, only through a passage passing through the oil hole of the first upper journal bearing.