Oil Control Ring Window-Hole Geometry for Deposit-Free Oil Drainage
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Solution Overview
Problem
Engine oil stagnation in the land space of oil control rings leads to deposit accumulation, which impairs oil scraping performance and causes unscraped oil to be released with exhaust gases, potentially causing the oil control ring to stick to the piston.
Innovation Solution
The oil control ring design features a web part with specific geometric configurations, including window holes and non-window hole parts, that satisfy certain dimensional and angular conditions to inhibit oil stagnation, ensuring efficient discharge and preventing deposit accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oil control ring uses a conventional land space design, then the structure is simple, but engine oil stagnates in the land space causing deposit accumulation
Solution Approach 1:
The land space is segmented into multiple regions by dividing the web part into first, second, and third web parts with different thicknesses. This segmentation creates distinct functional zones: the first land space for oil collection, the second land space as a transition zone, and the third land space for discharge, preventing oil stagnation while maintaining structural integrity.
Solution Approach 2:
Different portions of the web part are given different thicknesses to create local quality variations. The first web part has a first thickness, the second web part has a second thickness greater than the first, and the third web part has a third thickness greater than the second. This local differentiation optimizes oil flow characteristics in each region while addressing the stagnation problem.
2Productivity
If the oil control ring allows oil to flow through the land space, then oil discharge is enabled, but deposits accumulate when oil stagnates
Solution Approach 1:
The oil control ring structure is designed in advance to prevent oil stagnation before deposits can form. The progressive thickness increase from the first to the third web part creates a built-in flow direction that continuously moves oil through the land spaces and out through window holes, eliminating the preliminary condition for deposit accumulation.
Solution Approach 2:
The design converts the potential harm of oil stagnation into a benefit by using the land space structure to actively guide and accelerate oil flow. The varying web part thicknesses create pressure gradients that transform the land space from a stagnation zone into an active oil transport channel, improving discharge efficiency while preventing deposits.
3Ease of manufacture
If the web part has uniform thickness, then manufacturing is simple, but oil stagnation occurs in the land space
Solution Approach 1:
The web part thickness is made dynamic rather than uniform, creating a gradient structure where the first web part has a first thickness, the second web part has a greater second thickness, and the third web part has an even greater third thickness. This dynamic variation optimizes oil flow performance while remaining manufacturable through standard machining processes.
Data Source
AI summary
An oil control ring comprises: an oil ring having a pair of land parts arranged in a sliding direction and connected to each other by a web part; and a coil expander that biases the oil ring toward the outer circumferential side in the radial direction. The web part of the oil ring is provided with a plurality of window holes. In the axial cross-sectional view of the largest opening portion of the window hole in the axial direction of the oil ring, a width H1 in the sliding direction of the oil ring and a length L1 of a combustion chamber-side non-window hole part, which excludes the window hole, in the outer circumferential surface of the web part, satisfy the condition of 0.15>L1/H1≥0.