Polyimide Piston Ring Assembly for Oil-Free Hydrogen Wear Resistance

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Solution Overview

Problem

Existing piston rings for hydrogen gas compressors in oil-free environments lack adequate wear resistance and heat resistance, as evaluated tests were conducted only in oil-lubricated or air atmospheres, failing to account for the unique conditions in hydrogen environments.

Innovation Solution

A piston ring composed of thermoplastic polyimide as a main component with carbon fiber and/or graphite additives, achieving a tensile strength of 90 MPa or more and a bending strength of 150 MPa or more, along with a seal ring having lower strength for improved sealability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If thermoplastic polyimide resin is used as a main component for its heat resistance, then heat resistance is improved, but wear resistance in oil-free hydrogen environment is insufficient

Engineering Contradiction:

Improveheat resistanceVSAvoidwear resistance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The invention uses a composite material consisting of thermoplastic polyimide resin as the base material combined with PTFE (polytetrafluoroethylene) and carbon fiber additives. This composite structure leverages the heat resistance of polyimide while PTFE provides low friction and wear properties, and carbon fiber enhances mechanical strength, thereby resolving the contradiction between heat resistance and wear resistance in oil-free hydrogen environments.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention optimizes the compositional parameters by specifying that the thermoplastic polyimide resin content is 80-95 wt%, PTFE content is 5-20 wt%, and carbon fiber content is 1-10 wt%. By carefully controlling these parameter ranges, the material achieves both sufficient heat resistance from the polyimide matrix and adequate wear resistance from the PTFE and carbon fiber components.

Inventive Principle:

Principle #35Parameter changes

2Strength

If high strength piston ring is used, then mechanical strength is improved, but sealability is worsened

Engineering Contradiction:

Improvetensile strength and bending strengthVSAvoidsealability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention applies local quality by incorporating PTFE and carbon fiber additives specifically to address the interface between the piston ring and cylinder wall. The PTFE provides low-friction sliding properties at the contact surface, while the carbon fiber reinforces the structural integrity, allowing the piston ring to maintain both high overall strength and effective local sealability at the contact interface.

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

The piston ring assembly demonstrates enhanced wear resistance and heat resistance in hydrogen environments, ensuring long life and efficient hydrogen gas compression.

Implementation Method 1

The piston ring contains thermoplastic polyimide as a main component, and carbon fiber and/or graphite as an additive

Methodology Applied

Scientific EffectComposite materials: Composite Materials

Data Source

PatentUS12504072B2Piston ring, piston ring assembly, and reciprocating compressor

Publication Date: 2025.12.23 KOBE STEEL LTD

AI summary

A piston ring is a piston ring for use in an oil-free-type reciprocating compressor for compressing hydrogen gas, the piston ring containing thermoplastic polyimide as a main component and carbon fiber and/or graphite as an additive, and having a tensile strength of 90 MPa or more and a bending strength of 150 MPa or more.