| 摘要 |
PURPOSE: An engine piston is provided to restrain the waste of oil by making oil scraped via an oil ring along drain creases in the upper portion of a piston skirt portion. CONSTITUTION: A piston(4) is airtightly installed in a cylinder(2) to reciprocate upwardly and downwardly. The piston has a piston head(8) and first, second, and third lands(14). A first ring groove(16) is formed between the first and second lands, a second ring groove(18) between the second and third lands, and a third ring groove(20) between the third land and the upper end of a skirt portion(6) of the piston. First and second piston rings(22,24) for transmitting heat applied to the piston to a cylinder block(28) are mounted in the first and second ring grooves. An oil ring(26) for scraping down remnant oil is installed in the third ring groove. Many oil drain holes(30) are formed in the third ring groove. Drain creases(32) for draining oil are formed along the upper circumference of the skirt portion. The oil scraped down by the oil ring is promptly drained via the drain creases in the third ring groove. With the scraped oil, the skirt portion is lubricated. Therefore, the waste of oil is restrained.
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