Piston Ring Oblique Flank and Recesses for Groove Tilting
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Solution Overview
Problem
Piston ring grooves in internal combustion engines tilt due to thermal deformation, leading to altered hydrodynamic characteristics, increased oil film thicknesses, and poor oil scraping behavior, which existing solutions attempt to address by modifying the groove geometry, increasing manufacturing complexity and cost.
Innovation Solution
A piston ring with an oblique lower flank and recesses in the upper flank to compensate for tilting, maintaining a conventional rectangular cross-section, ensuring optimal contact with the cylinder wall by adjusting gas flow and pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recesses are introduced in the upper flank to restore gas flow, then the gas-tightness is improved, but the axial height at the external circumferential surface is reduced
Solution Approach 1:
The recesses are strategically positioned only in the upper flank region where gas flow restoration is needed, while preserving the full axial height at the external circumferential surface for structural integrity and thrust capacity. This localized modification achieves gas-tightness improvement without sacrificing overall ring height.
2Reliability
If the piston ring axial height is increased at the external circumferential surface to compensate for groove tilting, then the lower flank contact is improved, but the axial play is reduced leading to poor gas flow
Solution Approach 1:
The solution applies local geometric modifications: increasing axial height specifically at the external circumferential surface to improve lower flank contact, while simultaneously introducing recesses in the upper flank to restore axial play and gas flow. Each local modification addresses a specific functional requirement.
Solution Approach 2:
The piston ring is segmented into functional zones with different geometric characteristics: the external circumferential surface has increased axial height for improved contact, while the upper flank contains recesses for gas flow management. This segmentation allows simultaneous optimization of both contact quality and gas flow.
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 solution effectively compensates for groove tilting without increasing manufacturing complexity, maintaining gas-tightness and reducing blow-by losses by optimizing the axial play and gas flow, thus improving bearing and wear behavior.
Implementation Method 1
The piston of an internal combustion engine deforms during operation under the influence of the combustion heat and the temperature distribution resulting therefrom in axial direction differently
Implementation Method 2
the piston ring is no longer pressed optimally against the cylinder wall or respectively bush in the particularly critical thrust region
Data Source
AI summary
A piston ring for a piston of a piston engine has an external circumferential surface (2), and internal circumferential surface (4), and upper flank (6) pointing in the direction of the piston upper side, and a lower flank (8) pointing in the direction of the piston underside. The lower flank (8) runs obliquely with respect to the upper flank (6), so that axial height (A) of the piston ring is grater at the external circumferential surface (2) than the axial height (B) at the internal circumferential surface (4), and wherein on each side of the thrust of the piston ring at least one recess (10) is provided in the upper flank (6).