Oil Control Ring Spacer Expander Geometry for Lug Wear Control
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Solution Overview
Problem
In internal-combustion engines, the wear of lug parts in oil control rings due to contact with side rails leads to reduced surface pressure and deteriorated oil scraping performance, especially with higher engine rotation speeds and more lubricious engine oils, causing relative position shifts and increased wear.
Innovation Solution
An oil control ring design featuring a spacer expander with lug parts having a W/H ratio of 1.5 or more, where W is the width at 0.05 mm from the highest position and H is the height difference, along with rail facing parts that reduce sludge accumulation and wear, and protruding parts for improved slip resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine rotation speed is increased to achieve higher output, then the power increases, but the lug part wear increases due to higher reciprocation speed
Solution Approach 1:
The invention changes the geometric parameters of the lug part by defining a specific W/H ratio of 1.5 or more, where W is the width at 0.05mm from the highest position and H is the height difference. This parameter optimization reduces contact stress and wear while maintaining the oil control ring's functionality at higher engine speeds
Solution Approach 2:
The invention introduces a new dimensional relationship by specifying the width-to-height ratio of the lug part. This dimensional constraint creates an optimized contact geometry that distributes wear more evenly, allowing the system to operate reliably at higher speeds without increasing wear
2Loss of energy
If more lubricious engine oil is used to improve fuel efficiency, then the fuel efficiency improves, but the relative position shift between side rails and spacer expander increases
Solution Approach 1:
The invention optimizes the lug part geometry with a W/H ratio of 1.5 or more, which increases the contact area and improves positional stability. This geometric parameter change compensates for the reduced friction from more lubricious oils, preventing circumferential position shifts
3Reliability
If the lug part contact area is increased to reduce wear, then the wear resistance improves, but the surface pressure decreases
Solution Approach 1:
The invention defines a specific W/H ratio of 1.5 or more that optimizes the balance between contact area and surface pressure. This parameter optimization ensures sufficient wear resistance while maintaining adequate surface pressure for effective oil scraping performance
Data Source
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AI summary
An oil control ring according the present disclosure includes a pair of side rails, and a spacer expander disposed between the pair of side rails, in which the spacer expander includes a plurality of lug parts with which inner circumferential surfaces of the side rails are in contact, and a plurality of rail facing parts provided adjacent to the lug parts and facing side surfaces of the side rails, and all or at least a part of the plurality of lug parts satisfy a condition represented by a following inequality (1). W/H≥1.5 In inequality (1), W indicates a width (unit: mm) of each of the lug parts at a position 0.05 mm away from a highest position of the lug part in a direction of each of the rail facing parts, and H indicates a height difference (unit: mm) between a highest position of a region on the rail facing part adjacent to the lug part and the highest position of the lug part.