| 摘要 |
A two-stroke engine having an improved piston construction which reduces friction and wear between the piston and the cylinder wall, thereby providing cooler operation at any selected speed. The decreased wear increases piston life. The piston skirt, which is substantially parallel to the cylinder wall during normal operation, has a plurality of circumferentially spaced openings formed therethrough. These circumferentially spaced apart openings or holes, which are of a relatively small cross-sectional area compared with the area of the ports, are aligned with vertical continuous portions of the cylinder wall. The openings of the inlet, outlet, and transfer ports are located between the vertical continuous portions or ribs of the cylinder. The piston is disposed within the hollow inner portion of the cylinder for relative reciprocating motion. The openings in the cylinder skirt are aligned to move along the vertical ribs. As the piston reciprocates, the holes permit the fuel-air mixture in the crankcase to form a hydrostatic-type bearing between the piston and the cylinder wall. The disclosed bearing drastically reduces friction and results in substantially lower operating temperatures for the engine and provides reduced piston and cylinder wall wear. The openings through the piston skirt should generally be uniformly spaced around the skirt to provide for a uniform loading on the piston. Normally, the holes in the piston skirt will be formed in 180 DEG spaced apart pairs. It has been determined that three pairs, six holes, uniformly spaced around the piston skirt provide for good operating performance. More than one set of circumferentially spaced holes can be utilized in the piston skirt. Additional sets of circumferentially spaced bores can be vertically separated. Excellent operation can be obtained with three sets of vertically aligned and circumferentially spaced apart bores through the cylinder skirt.
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