Kabushiki Kaisha Riken

Takayuki Ichikawa

Junichi Takahashi

Gyo Muramatsu

Takashi Ono

Hiroshi Shimizu

Takuma Sekiya

Kazuya Mochiduki

A combined oil control ring comprising a pair of annular side rails each having a gap, and an axially corrugated spacer expander arranged between the side rails; the corrugated spacer expander having on the inside seating tabs for pushing inner peripheral surfaces of the side rails; the side-rail-pushing surface of each seating tab being provided with a nitrided layer; an entire surface of each spacer expander except for those provided with the nitrided layer being coated with a plating film; and the plating film having Vickers hardness HV0.01 of 300 or less.

Combined oil control ring

To provide a combined oil control ring comprising a pair of upper and lower side rails and an axially corrugated spacer expander having upper and lower portions for automobile engines, which is capable of keeping an excellent oil-controlling function without sticking between a spacer expander and side rails even in a long period of engine operation, the upper and lower portions of the spacer expander have tabs pushing inner peripheral surfaces of the side rails, projections supporting the side rails, and intermediate portions between the tabs and the projections; and each intermediate portion opposing the side rail has a center-raised bottom having a center-raised shape when viewed along a substantially circumferential direction center-raised shape and a radial direction.

A multi-piece oil ring is provided in which, even after long-term operation of an engine, adhesion and deposition of oil sludge are prevented, sticking of components does not occur, and a high oil control function can be maintained. The multi-piece oil ring includes a spacer expander and a pair of upper and lower side rails supported by the spacer expander. To achieve the above features, at least side faces of the side rails that face the spacer expander are coated with a fluorine-containing coating, and the spacer expander is coated with a metal coating. The angle of contact (&#x3b8;) of a paraffin-based lubricating oil with the portions of the side rails at 150&#xb0; C. that are coated with the fluorine-containing coating is 50&#xb0; or larger, and the angle of contact (&#x3b8;) of the paraffin-based lubricating oil with the portion of the spacer expander at 150&#xb0; C. that is coated with the metal coating is 10 to 50&#xb0;. The difference between &#x3b8;and &#x3b8;(&#x3b8;&#x2212;&#x3b8;) is 30&#xb0; or larger.

Growing community of inventors

Kashiwazaki, Japan

Takayuki Ichikawa