Patent ID: 7044472

Claim:
A combined steel oil control ring having steel side rails and a steel spacer expander, said spacer expander including ear portions for contacting the side rails, said ear portions being substantially equally spaced with respect to each other along an internal circumferential portion of said spacer expander, said ear portions having radially extending external, circumferential surfaces, said radially extending external circumferential surfaces of said ear portions being adapted to press said side rails radially outwardly through the use of the resilient force raised by the spacer expander, said spacer expander comprising: up-and-down contours, each formed circumferentially along said radially external circumferential surface of said ear portions said up-and-down contours each including at least two axially extending groove regions and at least three axially extending flat regions within each of said ear portions and having an aggregate circumferential width within a range of 30%-70% of the entire circumferential width of each said ear portion.