Piston Ring Recess Geometry for Defined Groove Sealing

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Solution Overview

Problem

Existing piston rings for internal combustion engines fail to effectively prevent oil carbon deposits and maintain a well-defined contact situation between the groove and cylinder, leading to blow-by issues.

Innovation Solution

A piston ring design featuring a recess with conical surfaces and a piston ring groove with a projection, where the surfaces are angled to create a specific contact configuration that reduces oil carbon accumulation and ensures a precise contact with the cylinder, incorporating wear protection coatings for enhanced durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional piston ring design is used, then the structure is simple and manufacturing is easy, but oil carbon deposits accumulate and sealing effectiveness deteriorates

Engineering Contradiction:

Improvesealing effectivenessVSAvoidpiston ring structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The piston ring is divided into multiple functional zones through the recess structure, creating distinct regions for sealing, oil control, and carbon deposit management. The recess separates the inner surface from the upper ring flank, allowing each zone to perform its specific function independently, thereby improving overall sealing effectiveness while maintaining manageable structural complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the piston ring are given different geometric properties through the recess structure. The conical surfaces within the recess provide specific contact characteristics for preventing carbon deposit accumulation, while other regions maintain properties optimized for sealing and oil control. This localized differentiation allows the ring to address multiple functional requirements simultaneously

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If trapezoidal rings are used to release oil carbon deposits, then carbon deposit accumulation is reduced, but the contact situation at the groove becomes less defined

Engineering Contradiction:

Improveoil carbon depositsVSAvoidcontact situation definition

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The recess structure introduces asymmetric geometry within the piston ring, with conical surfaces having specific angle ranges (10°-50° for the first surface, 5°-30° for the second surface). This asymmetric design creates a well-defined contact situation at the groove while maintaining the ability to release oil carbon deposits through the axial clearance variation

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention specifies precise parameter ranges for the recess geometry, including the angles of the conical surfaces and the axial height proportions (0.5-0.7 times the ring height). By controlling these parameters within defined ranges, the contact situation at the groove is precisely defined while the trapezoidal-like geometry continues to effectively release oil carbon deposits

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If cross-sectional weakenings are provided to give twist, then attachment behavior at the groove is improved, but structural strength is reduced

Engineering Contradiction:

Improveattachment behaviorVSAvoidring structural strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The recess structure acts as a nested feature within the piston ring body, creating internal geometric complexity without removing significant material. The conical surfaces are positioned within the ring thickness, allowing the twist and attachment behavior to be achieved while preserving the overall structural strength of the ring

Inventive Principle:

Principle #7Nested doll (Nesting)

4Duration of action of stationary object

If wear protection layers are added to surfaces, then durability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecomponent durabilityVSAvoidmanufacturing process

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

Wear protection layers are applied selectively to specific surfaces that require enhanced durability, such as the conical surfaces within the recess and the running surface. This localized approach provides wear protection where most needed while minimizing the overall manufacturing complexity compared to coating the entire ring

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11493129B2Piston ring and piston with internal groove sealing

Publication Date: 2022.11.08 FEDERAL MOGUL BURSCHEID GMBH

AI summary

A piston ring has a running surface, an inner surface, a lower ring flank, and an upper ring flank. A recess, extending across the perimeter in the shape of an internal angle, is located at the transition between the inner surface and the upper ring flank. The recess defines a conical first surface and a conical second surface at the piston ring. The first surface lies farther outward, when viewed in the radial direction, and farther above, when viewed in the axial direction, than the second surface. In an axial cross section, a first angle between the axial direction and the first surface lies in the range between 10° and 50°, and a second angle between the radial direction and the second surface lies in the range between 5° and 30°. A piston having a piston ring groove includes a projection on the groove bottom. A combination made from an above-mentioned piston ring and an above-mentioned piston are adapted to one another, so that the projection projects into the recess.