| 摘要 |
<p>A stepped piston (P, 19,31,50) for an engine of the kind having one or more cylinders (18, 30, 40, 51 the or each cylinder containing a stepped piston having a pumping part (4) of larger diameter, and a working part (1) of smaller diameter, the working part (1) of the piston (P, 19, 31, 50) being slidable in, and associated with, a working part of the cylinder (18, 30, 40, 51) in which combustion of a fuel/air mixture takes place, and the pumping part (4) of the piston being slidable in, and associated with, a pumping part of the cylinder, the piston having a body with an interior hollow (1, 1', 39, 45) opening to the outside of a lower end (5) of the piston, the body comprising a smaller diameter (1) working, part, extending from the top (2) of the piston (P, 19, 31, 50) to a step (3), and a larger diameter (4), pumping, part extending from the step (3) to a lower end (5) of the piston, at least one piston ring groove (6, 7; 20, 21, 22; 32, 33, 34; 41, 42, 43) formed in an outer surface of the smaller diameter part (1) and at least one piston ring groove (8, 9) formed in the outer surface of the larger diameter part (4), each piston ring groove, in use, receiving a piston ring (10, 11; 23, 24, 25; 35, 36, 37; 46, 47, 48; 12, 13), the smaller diameter part (1) of the piston having at least one metering opening (15, 16; 26; 38; 44; 70, 71) providing a through passage for lubricant, between the interior (1, 11; 39, 45) of the piston and the outer surface of the smaller diameter part (1) of the piston.</p> |
