OIL SCRAPER RING FOR PISTONS OF AN INTERNAL COMBUSTION ENGINE

Abstract

An oil scraper ring is provided for pistons (2) of an internal combustion engine having an oil scraper piston ring groove (4) formed without at least one oil drain bore. The scraper ring includes a ring body (6) comprising an upper ring flank (8), a lower ring flank (10), a ring inner side (12), a ring outer side (14) and two abutting surfaces (16, 18). An upper oil scraper rail (20) and a lower oil scraper rail (22) extend in the circumferential direction in spaced apart relation from one another in the axial direction and extend radially to the outside from the ring outer side (14) are arranged on the ring outer side (14). Oil passages (24) running in the radial direction are arranged in a region between the upper scraper rail (20) and the lower scraper rail (22), and at least one groove (26) extends in the radial direction on the lower ring flank (10).

Claims

1-12. (canceled)

13. An oil scraper piston ring of an internal combustion engine, comprising: a ring body comprising an upper ring flank, a lower ring flank, a ring inner side, a ring outer side, and two abutting surfaces; wherein the outer ring side includes an upper oil scraper rail and a lower oil scraper rail extending in a circumferential direction and spaced apart from one another in an axial direction and projecting radially outward from the ring outer; wherein at least one oil passage extends in the radial direction in a region between the upper scraper rail and the lower scraper rail, and wherein the lower ring flank includes at least one groove extending in the radial direction that has a depth or a width which decreases from the inside to the outside in the radial direction, and wherein the ring inner side includes a groove which runs in the circumferential direction for receipt of an expander spring.

14. The oil scraper ring according to claim 13, wherein the at least one groove has a semi-circular cross section.

15. The oil scraper ring according to claim 13, wherein the at least one groove comprises a plurality of grooves arranged at even angular distances in the circumferential direction on the lower ring flank.

16. The oil scraper ring according to claim 15, wherein each groove is arranged at an angular distance of 360/(n+1)° from another one of the at least one groove), in the case of a number of n>1 grooves, and wherein grooves, which are located closest to an oil scraper ring gap, likewise have an angular distance of 360/(n+1)° from said oil scraper ring gap in an oil scraper ring plane or oil scraper ring projection, respectively, based on a center point of the oil scraper ring.

17. The oil scraper ring according to claim 15, wherein six grooves are arranged on the oil scraper ring at an angular distances of 14.5° to 30.5°, 104.5° to 120.5°, 149.5° to 165.5°, 194.5° to 210.5°, 239.5° to 255.5°, and 329.5° to 345.5 from an abutting surface) in an oil scraper ring plane or from an abutting surface in an oil scraper ring projection, respectively, based on the center point.

18. The oil scraper ring according to claim 17, wherein the angular distances are 17.5° to 27.5°, 107.5° to 117.5°, 152.5° to 162.5°, 197.5° to 207.5°, 242.5° to 252.5°, and 332.5° to 342.5°.

19. The oil scraper ring according to claim 17, wherein the angular distances are 20.5° to 24.5°, 110.5° to 114.5°, 155.5° to 159.5°, 200.5° to 204.5°, 245.5° to 249.5°, and 335.5° to 339.5°

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Exemplary embodiments of the invention will be described in more detail below with reference to the figures based on schematic illustrations, wherein

[0025] FIG. 1 shows an oil scraper ring according to an embodiment of the invention, and

[0026] FIG. 2 shows an arrangement of the grooves on the oil scraper ring.

DETAILED DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows a cross sectional view of an oil scraper ring, which is installed in an oil scraper piston ring groove 4 of a piston 2 without oil drain means. The oil scraper ring has an upper ring flank 8, a lower ring flank 10, a ring inner side 12, and a ring outer side 14. The upper ring flank 8 is arranged on the combustion chamber side and the lower ring flank on the crankcase side. Two spaced-apart oil scraper rails are arranged on the ring outer side 14. The upper oil scraper rail 20 is arranged on the combustion chamber side and the lower oil scraper rail 22 on the crankcase side. The two oil scraper rails 20, 22 scrape oil off a non-illustrated cylinder inner wall, which forms the running surface for the piston.

[0028] Two types of oil passages are arranged in the ring body 6. Oil passages 24, which are arranged between the two oil scraper rails 20, 22 and which run to the ring inner side in the radial direction, on the one hand. Oil accumulating between the two oil scraper rails 20, 22 can drain to the ring inner side 12 through the oil passages 24. Grooves 26, which are arranged on the lower ring flank 10 and through which the oil can flow from the ring inner side 12 to the ring outer side 14 as well as from the ring outer side 14 to the ring inner side 12, on the other hand. The oil passages 24 as well as the grooves 26 run in a radial direction ring body 6. An axial direction corresponds to the longitudinal axis of the piston 2 or to the direction of movement thereof, respectively, and runs perpendicular to the radial direction.

[0029] A groove (32) running in the circumferential direction, in which an expander spring, preferably a tubular spring, runs, can further be seen in FIG. 1. The expander spring is suggested as circle. Compared to the one-piece oil scraper ring, a two-piece oil scraper ring comprising an expander spring has a significantly smaller cross sectional surface. The ring body 6 is thus relatively flexible and, in combination with the expander spring, displays a very good mold filling ability. The oil scraper ring is pressed predominantly by the expander spring against the cylinder wall. The expander spring is made of heat resistant spring steel. In the case of two-piece oil scraper rings, the radial pressure distribution is always virtually symmetrical because the contact pressure is evenly large over the entire coil spring circumference. To increase the service life, the outer diameters expander spring are ground, are wound more tightly on the abutting surfaces 16, 18, or are also covered with a Teflon tubing. Due to these measures, the bearing surface is enlarged, the surface loading is reduced, and the friction wear between ring body 6 and expander spring is thus reduced. The ring body 6 is either made of aluminum, grey cast iron, or steel.

[0030] FIG. 2 shows a top view in the axial direction of the ring body 6, wherein abutting surfaces 16, 18, an oil scraper ring gap 28, and a center point of the oil scraper ring 30 can be seen.

LIST OF REFERENCE NUMERALS

[0031] 2 piston [0032] 4 oil scraper piston ring groove [0033] 6 ring body [0034] 8 upper ring flank [0035] 10 lower ring flank [0036] 12 ring inner side [0037] 14 ring outer side [0038] 16, 18 abutting surfaces [0039] 20 upper oil scraper rail [0040] 22 lower oil scraper rail [0041] 24 oil passage [0042] 26 groove [0043] 28 oil scraper ring gap [0044] 30 center point of the oil scraper ring [0045] 32 groove running in the circumferential direction