Compression Piston Ring Recess Geometry for Flutter Suppression
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Solution Overview
Problem
Compression piston rings become unstable at high engine speeds, leading to radial or axial wobble and gas blow-by due to increased pressure, and existing designs with recesses on the upper flank increase the risk of ring fracture.
Innovation Solution
A piston ring design featuring recesses on the upper flank that extend radially outward or inward, with a chamfer at the edge between the interior and flank, and a twist in the installed state, which reduces axial clearance and enhances sealing by allowing combustion gases to flow through the recesses, thereby minimizing ring wobble and fracture risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If recesses are added to the upper piston ring flank to suppress ring wobble, then ring stability is improved, but the risk of ring fracture increases due to structural weakness
Solution Approach 1:
The recesses are designed with specific geometric characteristics (oblique lower edge at 3°-30° angle, radial extent limited to 75% of ring thickness, volume-to-circumference ratio of 0.04-0.08 mm²) to provide local gas flow channels that suppress wobble while maintaining overall ring strength. The localized modification allows gas to flow through the recesses to stabilize the ring without compromising the global structural integrity.
Solution Approach 2:
The recesses feature an asymmetric design where the lower edge runs obliquely to the upper piston ring flank, creating a specific flow direction for combustion gases. This asymmetric geometry optimizes the gas flow path to effectively suppress radial and axial wobble while minimizing impact on ring strength.
2Strength
If the piston ring is designed with conventional structure to maintain strength, then ring strength is preserved, but ring wobble occurs at high engine speeds due to increased pressure
Solution Approach 1:
The piston ring incorporates recesses that function as controlled porous structures, allowing combustion gases to flow through the ring body. This gas flow creates stabilizing pressure distribution that suppresses radial and axial wobble at high engine speeds while maintaining the overall structural strength of the ring.
Solution Approach 2:
The recesses utilize pneumatic principles by allowing combustion gases to flow through the ring structure. The gas flow through the recesses generates pressure forces that counteract the inertial forces causing wobble, stabilizing the ring position in the groove without requiring additional mechanical constraints.
3Stability of the object's composition
If recesses extend deeply into the piston ring to maximize wobble suppression, then ring stability improves, but the risk of fracture increases due to excessive material removal
Solution Approach 1:
The recesses are designed to extend radially only up to 75% of the ring thickness, providing sufficient depth to allow effective gas flow for wobble suppression while retaining enough material to maintain structural strength and prevent fracture. This partial penetration optimizes the balance between stability enhancement and structural integrity.
Solution Approach 2:
The recess geometry is optimized with specific parameters (radial extent limited to 75% of thickness, oblique angle of 3°-30°, volume-to-circumference ratio of 0.04-0.08 mm²) to achieve the maximum stabilizing effect while maintaining adequate structural strength. These parameter constraints ensure the recesses provide sufficient gas flow path length for wobble suppression without removing excessive material.
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 wobble and reduces the risk of fracture while maintaining effective sealing, minimizing axial clearance, and allowing controlled gas flow to prevent blow-by, thus improving engine performance at high speeds.
Implementation Method 1
allowing combustion gases to flow through the recesses, thereby minimizing ring wobble
Implementation Method 2
an increase in pressure before the ring when the piston ring is held by forces of inertia
Implementation Method 3
the lower edge of at least one recess runs obliquely to the upper piston ring flank
Implementation Method 4
enhances sealing by allowing combustion gases to flow through the recesses, thereby minimizing ring wobble
Data Source
AI summary
A piston ring is provided, in particular a compression piston ring having at least one recess with a lower edge running obliquely to the upper piston ring flank on its upper piston ring flank, the ring flank extending radially outward from the piston ring interior and radially inward from the piston ring bearing surface. The piston ring has a chamfer, which is opposite at least one recess. At least one recess and the chamfer extend in the radial direction up to at most the center of the cross-sectional area of the piston ring.