Four-cycle OHV engine

1. A four-cycle overhead valve (OHV) engine comprising:

a crankshaft disposed in a vertical direction;

an engine case housing and supporting the crankshaft; and

a camshaft disposed parallel to the crankshaft in the engine case housing and adjacently to the crankshaft, the camshaft including an intake-side cam and an exhaust-side cam, wherein:

a cylinder axis line is perpendicular to the vertical direction,

rotation of the camshaft opens and closes an intake valve and an exhaust valve via cam/push rod coupling,

the engine case housing includes bearings that rotatably support the crankshaft and the camshaft, an oil pump and lubricating oil passages that pump lubricating oil to the bearings, and an oil filter device that keeps the lubricating oil clean,

the lubricating oil passages include main lubricating oil passages, the main lubricating oil passages including communication portions linearly formed with extending portions, the communication portions communicating between the respective bearings of the crankshaft and the camshaft from outside the engine case housing, the extending portions extending from outside the engine case housing to the bearings of the camshaft,

the oil filter device is disposed on a side portion of one side of a cylinder body in a width direction in a cylinder head side with respect to the engine case housing in a space between a center line of the main lubricating oil passage and the cylinder axis line of the cylinder body, the oil filter device includes the oil pump disposed on the engine case housing, and the oil filter device further includes lubricating oil passages that connect the oil pump to the main lubricating oil passage,

the camshaft is disposed biased to the cylinder head side with respect to the crankshaft, and the oil pump is disposed on a lower engine case of the engine case housing corresponding to a shaft end portion of the camshaft, and

the main lubricating oil passages include outer portions inclining to a direction of the cylinder head such that the main lubricating oil passages intersect with the cylinder axis line with an acute angle.

2. The four-cycle OHV engine according to claim 1 , wherein

the oil filter device includes a cylindrically-shaped filter and a filter case that houses the filter, and

the filter case is disposed such that a central axis line of the cylindrical shape of the filter is parallel to an axis line of the crankshaft, and the filter case includes an opening configured to mount and remove the filter and a lid body that covers the opening.

3. The four-cycle OHV engine according to claim 1 , wherein

the engine has the cylinder axis line configured to be parallel with respect to a travelling direction of an outboard motor that includes the engine, and

an intake device that supplies engine combustion air is disposed on one side portion of the cylinder body on an opposite side to the oil filter device across the cylinder axis line.