A balance weight includes a main weight portion extending over a range defined by a circular-arc circumferential edge centered at a rotational shaft hole side and a pair of virtual end surfaces located on the circular-arc circumferential edge on both sides of the rotational shaft hole, a pair of extension weight portions extending from the pair of virtual end surfaces to an opposite circular-arc side of the rotational shaft hole from the circular-arc circumferential edge, the rotational shaft hole provided at the main weight portion so as to be located on a central side of the circular-arc circumferential edge, a crank shaft attachment protrusion, a crank shaft hole provided at the crank shaft attachment protrusion radially eccentrically with respect to the rotational shaft hole, and a pair of spaces formed between positions on both sides of the crank shaft attachment protrusion and the pair of extension weight portions, respectively.

Bearing 10 includes: a half bearing member having an inner circumferential face that slides against an associated shaft, and a plurality of recesses provided in a first end face in an axial direction of the associated shaft; a first flange member having a plurality of projections provided at positions corresponding to the plurality of recesses provided in the first end face; and a plurality of staking marks formed in a periphery of each recess when each recess is staked in a state where each of the plurality of projections is fitted to a corresponding one of the plurality of recesses in the first end face to fix the first flange member to the half bearing member. When staking marks formed on both sides of at least one of the plurality of recesses are viewed in a radial direction of the associated shaft, a volume of a deformed portion near a staking mark located outside in a circumferential direction is smaller than a volume of a deformed portion close to a staking mark located inside.

Bearing 10 includes: a half bearing member having an inner circumferential face that slides against an associated shaft, and a plurality of recesses provided in a first end face in an axial direction of the associated shaft; a first flange member having a plurality of projections provided at positions corresponding to the plurality of recesses provided in the first end face; and a plurality of staking marks formed in a periphery of each recess when each recess is staked in a state where each of the plurality of projections is fitted to a corresponding one of the plurality of recesses in the first end face to fix the first flange member to the half bearing member. When staking marks formed on both sides of at least one of the plurality of recesses are viewed in a radial direction of the associated shaft, a volume of a deformed portion near a staking mark located outside in a circumferential direction is smaller than a volume of a deformed portion close to a staking mark located inside.

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 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 crankcase oil catcher, the crankcase oil catcher comprising one or more surfaces configured to catch dispersed oil in a crankcase and direct the oil along the surfaces of the crankcase oil catcher away from a crankcase casing wall and towards a crank sump.

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.

A half bearing has a concave portion, a concave portion, and a concave portion penetrating from the outer circumferential surface to the inner circumferential surface, and the washer has a convex portion, a convex portion, and a convex portion on the inner circumferential surface side. The washer is moved to the outer circumferential surface side of the half bearing in a bent state, the convex portion is inserted into the concave portion, the convex portion is aligned with the position of the concave portion, and the convex portion is aligned with the position of the convex portion. Next, when the half bearing returns to its shape before being bent, the convex portion is accommodated in the concave portion, and the convex portion is also accommodated in the concave portion. Even if an axial force acts on the sliding bearing, the protrusion, the protrusion, and the protrusion engages with the concave portion, the concave portion, and the concave portion, so that the washer and the washer are not detached from the half bearing.

A half bearing has a concave portion, a concave portion, and a concave portion penetrating from the outer circumferential surface to the inner circumferential surface, and the washer has a convex portion, a convex portion, and a convex portion on the inner circumferential surface side. The washer is moved to the outer circumferential surface side of the half bearing in a bent state, the convex portion is inserted into the concave portion, the convex portion is aligned with the position of the concave portion, and the convex portion is aligned with the position of the convex portion. Next, when the half bearing returns to its shape before being bent, the convex portion is accommodated in the concave portion, and the convex portion is also accommodated in the concave portion. Even if an axial force acts on the sliding bearing, the protrusion, the protrusion, and the protrusion engages with the concave portion, the concave portion, and the concave portion, so that the washer and the washer are not detached from the half bearing.

A crankshaft and main bearing assembly for an internal combustion engine, includes: a crankshaft (1) with a first main bearing journal (10), a second main bearing journal (20), and one crankpin journal (110) parallel with, but radially spaced from and positioned between the first and second main bearing journals (10, 20). The first and second main bearing journals (10, 20), each have relevant first or second primary entrance openings (11, 21) in an outer surface for receiving fluid lubricant from the confronting first or second main bearing sleeves (210, 220). The one first crankpin journal (110) has a single exit opening (111) on an outer surface for supply of lubricant, in fluid communication with at least one of the primary entrance openings (11, 21). The main bearing journals (10, 20) on their outer surfaces each also have secondary entrance opening (12, 22) circumferentially spaced from the respective primary entrance openings (11, 21) and radially opposite thereto for also receiving fluid lubricant. The primary entrance opening (21) of the second main bearing journal (20) also is in an angularly spaced position with respect to the primary entrance opening (11) of the first main bearing journal (10), at an angle substantially greater than 0 degrees, but substantially less than 180 degrees. The secondary entrance openings (12, 22) are also in fluid communication with the single exit opening (111) of the one crankpin journal (110), and circumferential grooves of main bearing sleeves.