| 摘要 |
A lubricating apparatus for small-sized four-cycle engines to be used in portable type bush cutters, knapsack type powered sprayers, etc. In the lubricating apparatus, an oil returning channel is arranged to provide communication between a valve gear room and an oil sump, and an oil inhaling channel is branched from the middle of the oil returning channel so as to provide communication to an opening in an immediate lower portion of a skirt of a piston being at the top dead center. By this means, when a crank room is negatively pressurized, the oil sucked from the valve gear room is taken through the oil inhaling channel being in communication to a point inside a cylinder where the highest negative pressure is generated, and fed into the cylinder. An opening portion of the oil returning channel is provided with a check valve for opening when the engine is upright and closing when the engine inverted or slanted to prevent the backflow of oil from the oil sump to the oil returning channel. In order to carry out the returning of oil to the oil sump securely, the valve gear room further comprises an oil inhaling means being capable of immersing its extremity into the oil collected inside the valve gear room when the engine is put over sideways.
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