| 摘要 |
a four-stroke engine (1) is provided to lubricate driving parts including a crankshaft (24) and valve operating members while circulating oil, using pressure fluctuation in a crank chamber (23), the pressure fluctuation being caused by reciprocating motion of a piston (11). Cam driving parts (31, 33) move with rotation of the crankshaft (24) ; a driving chamber (51) and a rocker chamber (42) are connected to one another; the rocker chamber (42) is connected to the crank chamber (23) and a gas-liquid separator (81); an oil accumulated in a tank (62) is sucked up into the crank chamber (23) and circulated through each part of the four-stroke engine (1); the crank chamber (23) and the driving chamber (51) are connected to one another via a communicating passage (67) and a return passage (68); and the crank chamber (23) and the driving chamber (51) connected to one another via the return passage (68) communicate with one another only when the piston (11) is located in a vicinity of the top dead center. |
