Undercut Piston Ring Geometry for Lower Oil Consumption
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Solution Overview
Problem
In conventional piston rings with an undercut shape, oil on the cylinder inner wall can flow into the space between the piston ring and the ring groove during the downward stroke, leading to increased oil consumption.
Innovation Solution
The piston ring design features a cut surface with a second surface inclined away from the central axis, an angle of inclination between 50° and 85°, and a specific ratio of axial distances to facilitate oil flow to the crank chamber side, reducing the likelihood of oil entering the space between the piston ring and the ring groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional piston ring with an undercut is used, then oil scraping performance is improved, but oil flows into the space between the piston ring and ring groove leading to increased oil consumption
Solution Approach 1:
The invention applies a specific inclination angle (50° to 85°) to the second surface of the cut surface locally, while other parts of the piston ring maintain conventional design. This localized modification directs oil flow along the inclined surface toward the crank chamber side, preventing oil from entering the space between the piston ring and ring groove, thus resolving the contradiction between oil scraping performance and oil consumption
Solution Approach 2:
The invention changes the geometric parameters of the cut surface by specifying an inclination angle between 50° to 85° for the second surface and defining the ratio H/h1 between 0.2 to 0.4. These parameter modifications optimize the oil flow path along the cut surface, ensuring oil is directed to the crank chamber side while maintaining effective oil scraping performance
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 design effectively reduces oil consumption by ensuring that oil scraped off by the piston ring is directed to the outer circumferential side and dropped into the crank chamber, minimizing the amount that flows into the combustion chamber.
Implementation Method 1
a part of the oil scraped off by the piston ring flows along the slope of the second surface, so that the part of the oil can easily escape to the outer circumferential side of the piston ring and drop to the crank chamber side
Data Source
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AI summary
An outer circumferential surface of a piston ring has a cut surface forming a notched portion between an outer circumferential end surface and a lower surface, the cut surface including a first surface between the outer circumferential end surface and a bottom portion, and a second surface between the bottom portion and the lower surface. The second surface is inclined away from a central axis of the piston ring as it extends toward a crank chamber side, an angle of inclination of the second surface with respect to the bottom portion being greater than or equal to 50° and less than or equal to 85°. When an axial width of the piston ring is h1 and a distance in an axial direction between a connecting portion between the cut surface and the outer circumferential end surface and a connecting portion between the cut surface and the lower surface is H, H/h1 is greater than or equal to 0.2 and less than or equal to 0.4.