LUBRICATION SYSTEM FOR PORTABLE FOUR-CYCLE ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a lubrication system for a portable four-cycle engine including a passage for collecting oil and including a valve operating chamber of a simple structure suitable for production. SOLUTION: An opening end 36a on a valve operating chamber side of a breather passage 36 is provided at substantially a center of the valve operating chamber 30, and the valve operating chamber 30 includes a valve operating chamber cover 31 covering a valve mechanism. An inner cover 40 attached along an inner surface of the valve operating chamber cover 31 and forming a suction passage 45 with a shoulder disposed in a gap with a circumferential edge of a top plate portion of the cover is provided inside the cover. A cover-side direct passage 47 and a block-side direct passage 48 are provided which connect a suction passage 45 with a crank chamber 5a when negative pressure is created in the crank chamber 5a. Three or more suction tubes 46 that communicate with the suction passage 45 and extend to a crank lower side of the valve operation chamber are provided in the inner cover 40. At least one of opening ends 46b of the suction tubes 46 is provided lower than the opening end 36a of the breather passage 36 in an attitude of the engine 1 during use. COPYRIGHT: (C)2011,JPO&INPIT