Four-stroke internal combustion engine lubrication device

Abstract

There is provided a four-stroke internal combustion engine lubrication device that is capable of appropriately lubricating various parts regardless of engine orientation, of improving the capability for collecting excess oil within a valve chamber or the like and the capability for supplying oil to the various parts, and of reliably preventing oil leakage from a breather port provided in the valve chamber. It comprises: a reed valve (40) that allows oil flow from an oil chamber (17) into a crankcase (15) but prevents oil flow from the crankcase (15) to the oil chamber (17); an oil supply passage (35) for supplying oil from the crankcase (15) to a valve chamber (18); and a plurality of independent oil collection passages (51, 52) with differing inlet / outlet positions and for collecting in the oil chamber (17) the excess oil in the valve chamber (18). The dimensions of the various parts are so designed as to constantly maintain the oil chamber (17) under negative pressure during operation. The excess oil within the crankcase (15) is returned to the oil chamber (17) utilizing the negative pressure of the oil chamber (17).

Description

BACKGROUND INFORMATION[0001]The present invention relates to a lubrication device for a four-stroke internal combustion engine that is suitable for use as a power source of a portable work machine such as a brush cutter, a chain saw, etc., and more specifically to a four-stroke internal combustion engine lubrication device that is so arranged as to be capable of appropriately lubricating various parts regardless of the orientation of the work machine (engine), of improving the capability for collecting excess oil within a valve chamber, etc., and the capability for supplying oil to the various parts, and of reliably preventing oil leakage from a breather port (blow-by gas discharge port) provided in the valve chamber.[0002]JP Patent Publication (Kokai) No. 2002-188423 A (“Patent Document 1”), incorporated by reference herein, discusses four-stroke internal combustion engines that are suitable for use as power sources of portable work machines such as brush cutters, chain saws, etc.,...

AI Technical Summary

Benefits of technology

[0005]An aspect of the present invention includes a four-stroke internal combustion engine lubrication device that is capable of appropriately lubricating various parts regardless of the orientation of the engine, of improving the capability for collecting excess oil within a valve chamber, etc., and the capability for supplying oil to the various parts, and of reliably preventing oil leakage from a breather port (blow-by gas discharge port) provided in the valve chamber.

[0020]In addition, since the oil chamber that surrounds the crankcase is so shaped as to comprise an expansive bulging portion in the direction in which the one-way valve is provided so that the one-way valve would always be maintained at a position above oil level regardless of engine orientation, oil is prevented from flowing into the crankcase while still in liquid form, and it is possible to reliably supply to the crankcase oil that has been turned into mist.

Problems solved by technology

However, conventional four-stroke internal combustion engine lubrication devices such as those discussed above do not sufficiently address changes in the orientation of the engine, and are deficient in terms of their capability for collecting excess oil within the valve chamber, etc., and their capability for supplying oil to various parts.

Thus, there are such problems as leakage of excess oil from within the valve chamber to the outside through the breather port (blow-by gas discharge device), etc.

Further, when a reed valve is used for the one-way valve, the reed valve opens as the piston rises and the crankcase becomes negatively pressured (i.e., lower in pressure than the oil chamber).

Further, if the plurality of oil collection passages are integrated (merged) midway, gas would be more readily sucked in than liquid, thereby making oil collection difficult.

Images