GB871901A - Piston and rings for use therewith - Google Patents

Abstract

871,901. Pistons. COSSOR, S. N. J. Dec. 30, 1958 [Jan. 24, 1958; March 21, 1958; June 26, 1958], No. 42038/58. Class 122 (1). A piston 10, Fig. 3, comprises a head portion 12 and a skirt portion 11, at least two ring grooves in the head, passages 21, 22 connecting the uppermost groove 13 with the top of the head and holes 25, 26 connecting the remaining groove or grooves 17, 18 with the interior of the piston. The groove 13 accommodates three compression rings 14, 15, 16 which, during operation, are forced into sealing contact with the cylinder wall by gas pressure entering the passages 21, 22, which are circumferentially spaced around the piston, and acting upon the inner faces of the rings. The grooves 17, 18 are fitted with oil-control rings 19, 20 which are prevented from rotation by a spring plate 27 having end lugs 28, 31 passing through slots 29, 32 in the piston and engaging with recesses 30, 33 in the rings; the spring plate may be corrugated to increase its flexibility. In order to facilitate the return of the oil to the sump, the lower edges of the grooves 17, 18 are of less diameter than the piston and lead into inclined grooves 23, 24 which also connect with circumferentially-spaced holes 25, 26. In the modification, shown in Fig. 6, the compression ring 45 is mounted in a groove 43 between rings 44, 46 and is split into a number of segments which are connected by a retaining bard 47 engaging with slots formed in the inner surface of the segments; the ring 45 may be in the form of a continuous ring and, if desired, wide enough to fit completely the groove, the rings 44, 46 then being dispensed with. An oil-control ring 49 is mounted in a groove 48 and is split into a number of segments each urged into sealing contact with the cylinder by springs 53; an oil-groove 54 connected with the interior of the piston is formed below the groove 48. In a further modification shown in Fig. 10, the oil-control ring is formed from a number of plain rings 69 mounted above a corrugated ring 70; a further plain ring 71 may be arranged below the ring 70. Two expansion-controlling slots 39, Fig. 3, are formed diametrically opposite each other in the skirt 11 so as to terminate near the lower edge of the skirt or, if desired, only one such slot may be provided.