Combined Oil Control Ring Center-Raised Spacer Expander
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Solution Overview
Problem
Conventional oil control rings in internal combustion engines suffer from oil sludge accumulation, leading to sticking between the spacer expander and side rails, which hinders their oil-controlling function and durability, especially in engines with repeated start and stop cycles.
Innovation Solution
The combined oil control ring features an axially corrugated spacer expander with center-raised bottoms in its intermediate portions, allowing oil to flow circumferentially or radially, combined with a resin or metal coating to prevent sludge accumulation, ensuring effective oil flow and reduced sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the space between the spacer expander and side rails is made narrow to reduce oil consumption, then oil consumption is reduced, but oil sludge accumulation increases causing sticking between components
Solution Approach 1:
The intermediate portions of the spacer expander are designed with convex shapes (curved surfaces) that protrude toward the side rails. This curvature prevents oil sludge from accumulating in flat spaces by creating a shape that facilitates oil flow and prevents stagnation, thereby preventing sticking while maintaining narrow spacing for low oil consumption
Solution Approach 2:
The spacer expander features localized convex intermediate portions at specific locations where oil sludge accumulation is most problematic. This local structural modification targets the specific problem areas without changing the overall narrow design of the oil ring, allowing prevention of sticking only where needed while maintaining low oil consumption globally
2Loss of energy
If the oil ring is designed with small axial width to improve followability and reduce friction loss, then friction loss is reduced, but oil sludge accumulation in narrow spaces increases causing sticking
Solution Approach 1:
The convex intermediate portions with curved surfaces prevent oil sludge accumulation in the narrow axial width design by creating flow-friendly geometry. This allows the oil ring to maintain small axial width for good followability and low friction loss while preventing sticking through the curvature-induced oil flow pattern
Solution Approach 2:
The convex intermediate portions dynamically facilitate oil flow during engine operation. As the spacer expander moves axially during combustion cycles, the convex shapes continuously promote oil drainage and prevent static accumulation, maintaining reliability in the narrow small-width design
3Ease of manufacture
If conventional flat intermediate portions are used in the spacer expander, then manufacturing is simple, but oil sludge accumulates in the spaces between intermediate portions and side rails
Solution Approach 1:
The intermediate portions are formed with convex curved surfaces that can be manufactured using standard forming processes. The curvature is achieved through simple wire forming or rolling operations, maintaining ease of manufacture while effectively preventing oil sludge accumulation through the curved geometry that promotes oil flow
Data Source
Figure 1(a)~2
Figure 3(a)~3(b)
AI summary
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.