Compression Piston Ring Recess Geometry for Ring Chatter Control
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Solution Overview
Problem
Compression piston rings in internal combustion engines become unstable at higher engine speeds, leading to radial or axial ring chatter and increased blow-by due to inertial forces, which existing designs fail to adequately address without compromising the ring's integrity.
Innovation Solution
A piston ring design featuring a plurality of recesses on the upper flank with inclined lower edges and a chamfer on the edge between the inner side and the lower flank, which extends radially up to the centroid of the axial cross-sectional area, providing a negative or positive twist to enhance sealing and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recesses are added to the upper piston ring flank to suppress ring flutter, then sealing performance is improved, but structural strength is weakened
Solution Approach 1:
The recesses are strategically positioned only on the upper piston ring flank where gas pressure acts to stabilize the ring, while the lower flank maintains full thickness for strength. This localized modification provides sealing enhancement exactly where needed without compromising overall ring integrity.
Solution Approach 2:
The recesses are pre-formed during manufacturing to create optimal gas flow paths that will stabilize the ring during operation. The inclined lower edges are designed in advance to guide combustion gases effectively into the ring groove, preventing flutter before it occurs.
2Reliability
If the radial extent of recesses is increased to improve gas flow, then sealing is enhanced, but ring strength is reduced
Solution Approach 1:
The radial extent of recesses is optimized to a specific range (10-30% of ring thickness) that balances gas flow requirements with structural integrity. The inclined lower edges are designed with specific angles (15-45 degrees) to maximize gas flow efficiency while maintaining adequate material strength.
3Reliability
If chamfer is extended radially to suppress flutter, then sealing performance improves, but manufacturing complexity increases
Solution Approach 1:
The solution is divided into two separate but complementary features: recesses on the upper flank and a chamfer on the lower flank. This segmentation allows each feature to be optimized independently for its specific function while simplifying the overall manufacturing process compared to a single complex modification.
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 suppresses ring chatter while maintaining structural integrity by allowing combustion gases to press the piston ring strongly against the cylinder wall, minimizing axial play and oil flow, and reducing the risk of breakage.
Implementation Method 1
a pressure increase in front of the ring when the piston ring is held against its upper flank by inertial forces
Implementation Method 2
the piston ring is held against its upper flank by inertial forces
Implementation Method 3
the piston ring has a chamfer at the edge between the inner piston ring surface and the lower piston ring flank
Implementation Method 4
the piston ring has a negative twist in the installed state
Data Source
Figure 1A~1B
Figure 2A~3
Figure 4~5
AI summary
The invention relates to a piston ring, in particular a compression piston ring, comprising, on a top piston ring flank, at least one recess having a bottom edge extending obliquely with respect to the top piston ring flank, which recess extends radially outward from the inside of the piston ring or extends radially inward from the piston ring running surface. The piston ring has a chamfer opposite the at least one recess. The at least one recess and the chamfer extend in the radial direction at the most up to an area centre of gravity of a cross-sectional area of the piston ring.