Oil Control Ring Side Rail Geometry for High-Speed Sealing
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Solution Overview
Problem
Internal combustion engines operating at high rotation speeds experience increased oil consumption due to the destabilized behavior of traditional oil control rings, which fail to effectively seal the cylinder bore.
Innovation Solution
A side rail with a vertically symmetrical shape and specific curvature ratios for its inner peripheral surface, combined with a spacer expander, stabilizes the oil control ring's behavior at high speeds, enhancing sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner peripheral surface of the side rail is rounded in a semicircular shape (conventional design), then the manufacturing is simple, but the oil consumption increases at high rotation speeds due to unstable behavior of the oil control ring
Solution Approach 1:
The invention changes the geometric parameters of the inner peripheral surface by defining a specific curvature radius ratio (R1/h0 between 0.7-1.1) for the inner tip portion. This parameter optimization ensures stable behavior of the side rail during high-speed reciprocation, maintaining reliable sealing performance while preventing excessive oil consumption that occurs with conventional semicircular designs.
Solution Approach 2:
The invention introduces asymmetry in the curvature distribution of the inner peripheral surface. Instead of a uniform semicircular shape, the inner tip portion has a specifically designed asymmetric curvature profile where the curvature radius varies along the height, creating optimal contact characteristics with the piston groove that stabilize the oil control ring behavior at high speeds.
2Reliability
If the curvature radius R1 of the inner tip portion is increased to improve sealing, then the sealing performance improves, but the side rail behavior becomes unstable at high speeds increasing oil consumption
Solution Approach 1:
The invention establishes an optimal parameter range for the curvature radius ratio (R1/h0 between 0.7-1.1) that simultaneously achieves stable side rail behavior and reliable sealing performance. This parameter optimization prevents both the instability that leads to oil consumption and the excessive sealing that causes behavioral instability.
Solution Approach 2:
The invention applies a specific degree of curvature (not maximum, not minimum) to the inner tip portion. By using a moderate curvature radius within the specified range, the design achieves sufficient sealing performance without creating excessive contact pressure or instability, balancing both requirements optimally.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A side rail forms an oil control ring together with a spacer expander, and includes: an outer peripheral surface; an inner peripheral surface having a vertically symmetrical shape in an axial cross section; a first side surface; and a second side surface. The inner peripheral surface includes an inner tip portion satisfying following Condition 1 in an axial cross section. 0.7≤R1/h0≤1.1 In the expression, R1 represents a curvature radius (unit: mm) of a curve forming the inner tip portion, and h0 represents a height (unit: mm) of the side rail.