Trapezoidal Piston Ring Opening for Single-Side Sealing

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Solution Overview

Problem

Existing piston rings with V-shaped openings face issues with inconsistent size matching, leading to excessive friction, reduced sealing effectiveness, and high blowby and oil consumption due to imperfect size alignment.

Innovation Solution

A piston ring with a trapezoidal opening design featuring varying thicknesses on either side of the opening, with a boss and groove configuration that ensures single-side sealing, reducing blowby and oil consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a V-shaped opening is used in the piston ring, then the sealing effect is improved, but the blowby quantity and engine oil consumption increase due to size matching issues

Engineering Contradiction:
Improvesealing effectVSAvoidblowby quantity and engine oil consumption
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies asymmetry by changing the opening shape from V-shaped to trapezoidal, creating unequal thickness distribution on both sides of the opening. This asymmetric design allows the thicker side to provide better sealing while the thinner side reduces resistance, thereby improving sealing effectiveness without increasing blowby or oil consumption.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent implements local quality by varying the thickness of the piston ring locally around the opening. The trapezoidal design creates different thicknesses at different locations, with the thicker portion providing enhanced sealing capability and the thinner portion reducing overall resistance to gas flow, thus addressing sealing issues without proportionally increasing blowby.

Inventive Principle:
Principle #3Local quality

2Reliability

If the piston ring size is increased to improve sealing, then the sealing effect is improved, but the friction increases due to excessive contact with the cylinder liner

Engineering Contradiction:
Improvesealing effectVSAvoidfriction
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent uses local quality by concentrating the increased thickness only where needed for sealing (at specific portions around the opening) rather than uniformly increasing the entire piston ring size. This localized thickening provides improved sealing at the critical areas while maintaining smaller overall dimensions, thus reducing friction with the cylinder liner.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The trapezoidal opening design segments the piston ring thickness into different zones, with thicker sections positioned to provide sealing and thinner sections reducing friction. This segmentation allows the piston ring to have different functional characteristics at different locations, achieving both improved sealing and reduced friction.

Inventive Principle:
Principle #1Segmentation

3Force

If the piston ring size is decreased to reduce friction, then the friction is reduced, but the opening size increases leading to excessive blowby quantity

Engineering Contradiction:
ImprovefrictionVSAvoidblowby quantity
Core Design Contradiction:
ForceVSLoss of substance

Solution Approach 1:

The patent applies local quality by strategically positioning thicker portions of the piston ring at the opening areas to maintain sealing effectiveness, while the overall ring size remains smaller to reduce friction. The localized thickness variation ensures that blowby is controlled at the opening without requiring a larger overall ring dimension.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4575275B1Piston ring with trapezoidal openning
Publication Date: 2026.04.15 MAHLE AUTOMOTIVE TECH (CHINA) CO LTD
  • EP4575275B1 patent drawingFigure 1~3
  • EP4575275B1 patent drawingFigure 4~5

AI summary

The present invention relates to a piston ring with a trapezoidal opening, used for being sleeved on a piston ring groove of a piston and comprising a piston ring main body with an opening, wherein the piston ring main body is processed with at least one trapezoidal boss at an end of one side of the opening, and is processed with at least one groove matched with the trapezoidal boss at an end of the other side of the opening; a height of the boss is not greater than a depth of the groove; and the piston ring has different thicknesses on two sides of the opening, so that only one side surface of the trapezoidal boss is in contact with a corresponding side surface of the groove in the operation process of an engine.