Color-Layer Piston Ring Coating for Visual Wear Indication

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Solution Overview

Problem

Existing methods for determining piston ring wear in two-stroke engines are complicated and inconvenient, requiring calibration and handling of ultrasonic devices, and do not allow for easy identification of wear state or timely replacement.

Innovation Solution

A piston ring with radially superimposed thermally sprayed layers of different colors, including a copper-based layer for wear indication, allowing for simple visual evaluation of wear patterns and enabling detection of excessive or uneven wear through color transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ultrasonic devices are used to determine residual thickness of piston ring, then measurement capability is achieved, but device complexity and ease of operation deteriorate due to calibration requirements and handling inconvenience

Engineering Contradiction:
Improveresidual thickness measurementVSAvoidultrasonic device complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies multiple radially superimposed thermal spray layers with different colors (at least two different colors in a fixed sequence) to the piston ring surface. As the piston ring wears, these colored layers are removed sequentially, providing visual indication of wear stages. This eliminates the need for complex ultrasonic measurement devices while maintaining measurement capability through simple visual inspection of the color sequence.

Inventive Principle:
Principle #32Color changes

2Measurement precision

If ultrasonic devices are used to determine residual thickness of piston ring, then measurement capability is achieved, but ease of operation deteriorates due to handling inconvenience

Engineering Contradiction:
Improveresidual thickness measurementVSAvoidwear determination operation
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The colored thermal spray layers provide immediate visual feedback on piston ring wear status. Operators can quickly assess wear by observing which color layer is currently visible, eliminating the need to handle and operate complex ultrasonic devices. The fixed sequence of colors makes interpretation straightforward and operationally simple.

Inventive Principle:
Principle #32Color changes

3Loss of information

If multiple radially superimposed thermal spray layers with different colors are applied, then wear indication capability is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvewear state informationVSAvoidpiston ring manufacturing
Core Design Contradiction:
Loss of informationVSEase of manufacture

Solution Approach 1:

The patent uses composite thermal spray layers containing copper particles (3-50% by weight) mixed with other materials to achieve both functional and visual properties. The different colored layers are applied in a fixed radial sequence, with each layer containing specific material compositions. This composite approach allows manufacturing of multiple functional layers with distinct visual characteristics through a standardized thermal spray process.

Inventive Principle:
Principle #40Composite materials

4Loss of information

If copper content in lowermost layer is between 30-50% by weight, then color identification is improved, but material cost increases

Engineering Contradiction:
Improvelayer identificationVSAvoidcopper content
Core Design Contradiction:
Loss of informationVSQuantity of substance

Solution Approach 1:

The patent applies copper-containing thermal spray material specifically to the lowermost radial layer(s) where wear indication is most critical, with copper content optimized at 3-50% by weight. This localized application of copper provides strong color identification (reddish hue) exactly where needed for wear assessment, while other layers may use different material compositions. This selective material distribution achieves effective wear indication without unnecessarily increasing overall material costs.

Inventive Principle:
Principle #3Local quality

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

Facilitates quick and easy assessment of wear state, allowing for timely replacement and extending service life by providing clear visual cues for wear status through color sequences and gradients, ensuring operational reliability, especially in critical applications like marine diesel engines.

Implementation Method 1

at least two radially superimposed layers of thermal spray layers are provided, of at least two different colors in a fixed sequence

Methodology Applied
Scientific EffectThermal spray:

Implementation Method 2

the radially lowermost layer or layers are made reddish by the addition of Cu or CuFeAl, the copper content of the lowermost layer or layers preferably being between 30 and 50% by weight

Methodology Applied
Scientific EffectColor identification through copper content:

Data Source

PatentEP3717803B1Piston ring for two-stroke engines with a wear display
Publication Date: 2023.02.22 FEDERAL MOGUL BURSCHEID GMBH
  • EP3717803B1 patent drawingFigure 1~2

AI summary

The invention relates to a piston ring for a two-stroke engine with a wear display, comprising a piston ring body with an outer face, two piston ring flanks, and a piston ring inner face. The invention is characterized in that the outer face is equipped with at least two layers of thermally sprayed layers which lie one over the other radially and which have at least two different colors in a determined order and can thereby be differentiated by color. The radially lowermost layer or lowermost layers are dyed red by adding Cu or CuFeAl, wherein preferably the copper component of the lowermost layer or the lowermost layers is between 30 and 50 wt.%.