Notched Piston Ring Geometry for Lower Engine Oil Consumption
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Solution Overview
Problem
In internal combustion engines with conventional piston rings having an undercut, oil can flow onto the undercut surface and into the space between the piston ring and the ring groove, leading to increased oil consumption.
Innovation Solution
A piston ring design featuring an outer circumferential surface with a cut surface forming a notch, where the second surface is inclined away from the central axis, allowing oil to easily escape to the outer side and prevent flow into the space between the ring and the groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
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, increasing oil consumption
Solution Approach 1:
The undercut is segmented into multiple surfaces (first surface, second surface, third surface) with different orientations. The second surface is inclined away from the cylinder center, while the first and third surfaces face different directions, creating distinct flow paths for scraped oil that prevent it from entering the gap between the piston ring and ring groove.
Solution Approach 2:
Different portions of the undercut have different surface qualities and orientations tailored to specific functions. The second surface is specifically designed with an inclination angle of 10-45 degrees to guide oil away from the gap, while other surfaces have different characteristics optimized for their local roles in oil control.
2Loss of substance
If the second surface of the cut surface is inclined away from the central axis, then oil is directed away from the ring groove, but the structural complexity of the piston ring increases
Solution Approach 1:
The inclination angle of the second surface is optimized within a specific range (10-45 degrees) to achieve effective oil diversion. This parameter optimization balances the competing requirements of oil control performance and manufacturing feasibility, avoiding excessive complexity while maintaining effectiveness.
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
This design effectively reduces oil consumption by ensuring that oil scraped off by the piston ring is directed away from the ring groove, preventing it from flowing into the combustion chamber.
Implementation Method 1
the second surface is inclined away from a central axis of the piston ring as it extends toward the crank chamber side
Implementation Method 2
an angle of inclination of the second surface with respect to the lower surface in a cross section orthogonal to the circumferential direction of the piston ring is greater than or equal to 50° and less than or equal to 85°
Data Source
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.