Piston Ring Flank Seal for Blowby Reduction

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Solution Overview

Problem

Existing piston rings face challenges in sealing the gap between the lower ring flank and the piston ring groove flank due to surface roughness and waviness, leading to gas flow and deformation under thermal influences, which affects the seal's effectiveness and longevity.

Innovation Solution

A piston ring design featuring a ring flank seal groove on the lower flank with openings allowing combustion gases to press a seal against the piston ring groove flank, utilizing elastic materials and specific groove shapes like trapezoidal or dovetail to enhance sealing without completely closing the gap, allowing for axial movement and pressure distribution across surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a seal is placed in the ring flank seal groove to reduce blowby, then sealing effectiveness is improved, but the piston ring's freedom of rotation and heat transfer may be compromised

Engineering Contradiction:

Improvesealing effectivenessVSAvoidfreedom of rotation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The seal is positioned locally in the ring flank seal groove at the lower ring flank, providing enhanced sealing at the critical blowby location without affecting the overall rotation and heat transfer properties of the piston ring. The seal groove is strategically placed to target only the specific sealing issue at the lower flank-piston groove interface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The piston ring sealing function is segmented into multiple zones: the traditional crown seal at the upper flank and the new ring flank seal at the lower flank. This segmentation allows each seal to address specific sealing needs in different locations, improving overall sealing effectiveness while maintaining the ring's operational characteristics.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the wall thickness of the piston ring is weakened to improve seal mobility, then the seal's ability to conform to surfaces is improved, but the structural strength of the piston ring is reduced

Engineering Contradiction:

Improveseal mobilityVSAvoidstructural strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

Instead of weakening the piston ring wall thickness to improve seal mobility, the invention provides mobility in the axial dimension by creating a ring flank seal groove that allows the seal to move up and down within the groove. This dimensional approach maintains the ring's structural strength while achieving the necessary seal conformability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Force

If openings are created to allow combustion gases to press the seal against the groove flank, then sealing pressure is improved, but the structural integrity of the ring is compromised

Engineering Contradiction:

Improvesealing pressureVSAvoidstructural integrity

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The invention converts the harmful blowby gases that were previously causing sealing problems into a beneficial force. By creating openings that allow combustion gases to access the ring flank seal groove, the gases press the seal against the lower piston ring groove flank, transforming the problematic gas flow into the sealing mechanism that prevents further blowby.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly reduces gas leakage ('blowby') while maintaining the piston ring's freedom of rotation and heat transfer, extending the seal's service life by using materials with high thermal expansion and precise adjustment for optimal sealing performance.

Implementation Method 1

combustion gases can enter the ring flank seal groove through the openings and press a ring flank seal arranged therein downward against the lower piston ring groove flank

Methodology Applied

Scientific EffectGas pressure: Pressure Increase

Implementation Method 2

The material of the ring flank seal has a significantly higher coefficient of thermal expansion than the material of the piston ring itself

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 3

The material of the ring flank seal has a significantly higher coefficient of thermal expansion than the material of the piston ring itself

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10436323B2Piston ring having a groove seal

Publication Date: 2019.10.08 FEDERAL MOGUL BURSCHEID GMBH

AI summary

A piston ring (2) has at least one ring flank seal (14) arranged on a lower ring flank (8) of the piston ring.