Combined Oil Control Ring With Nitrided Spacer Tabs
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Solution Overview
Problem
Existing combined oil control rings face challenges with high tension variation, wear resistance, and sludge resistance due to issues with Ni plating films chipping or peeling, which affect their conformability and oil consumption in engines with improved combustion efficiency.
Innovation Solution
A combined oil control ring design featuring a Ni plating film with specific crystal orientations and structure, heat-treated to prevent chipping and peeling, and a nitrided layer on side-rail-pushing surfaces, with the Ni plating film acting as a nitridation-preventing film and anti-sticking layer, ensuring low tension variation and excellent wear and sludge resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a nitrided layer is formed on the spacer expander to improve wear resistance, then wear resistance is improved, but the Young's modulus and developed length increase, resulting in larger tension variation
Solution Approach 1:
The patent applies nitriding treatment selectively only to the side-rail-pushing surfaces of the spacer expander, rather than the entire surface. This localized approach provides wear resistance where needed while minimizing the increase in Young's modulus and developed length, thus controlling tension variation within acceptable ranges.
Solution Approach 2:
The spacer expander surface is divided into two functional zones: nitrided surfaces for wear resistance at contact points, and non-nitrided surfaces to maintain original mechanical properties and tension characteristics. This segmentation allows simultaneous achievement of wear resistance and tension control.
2Adaptability or versatility
If the width of side rails is reduced to improve conformability, then conformability coefficient is improved, but the oil ring becomes more susceptible to sticking and wearing
Solution Approach 1:
The patent applies different surface treatments to different parts of the oil ring: Ni plating on non-contact surfaces for anti-sticking protection, and nitriding on side-rail-pushing surfaces for wear resistance. This allows narrow side rails to maintain conformability while being protected against sticking and wearing through localized surface engineering.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves low tension variation and enhanced wear and sludge resistance, reducing fuel consumption and maintaining performance in engines with improved combustion efficiency by preventing Ni plating film defects and ensuring effective nitridation and anti-sticking properties.
Implementation Method 1
Patent Reference 7 teaches that the Ni plating film suppresses the sticking of oil sludge, because of its surface free energy and hydrogen bonding force.
Implementation Method 2
a side-rail-pushing surface of each seating tab being provided with a nitrided layer
Implementation Method 3
a Ni plating film acting as a nitridation-preventing film
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
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.