Patent ID: 11873780
Assignee: NIPPON PISTON RING CO., LTD.
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A combined oil ring, comprising:
a pair of upper and lower side rails fitted in an oil ring groove of a piston, the pair of upper and lower side rails each being formed in a planar and annular shape and having a sliding contact portion in sliding contact with a cylinder; and
a spacer expander disposed between the pair of upper and lower side rails and having a seating tab portion, the seating tab portion comprising an upper seating tab portion and a lower seating tab portion for pressing the pair of upper and lower side rails outward,
wherein, each in the pair of upper and lower side rails has, in a sectional shape of the sliding contact portion taken along an axial direction of the piston, an outermost diameter portion located below a center of an axial direction width of the pair of upper and lower side rails,
the combined oil ring comprises an anti-tilt device that prevents the pair of upper and lower side rails from tilting due to sliding contact with the cylinder at positions where the upper seating tab portion and the lower seating tab portion come into contact with inner peripheral sides of the pair of upper and lower side rails,
the anti-tilt device has contact surfaces in the upper seating tab portion and the lower seating tab portion contacting with the upper side rail and the lower side rail respectively, the contact surfaces having an upper inclined surface and a lower inclined surface, each sectional shape of the inclined surfaces along the axial direction of the piston being inclined with respect to the axial direction of the piston by a predetermined angle, and
the inclined angle θ1 of the upper inclined surface is defined to be smaller than the inclined angle θ2 of the lower inclined surface.