Piston Ring Edge Rolling for Fatigue Strength
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Solution Overview
Problem
Conventional piston rings are prone to cracking and fracture due to thermal and dynamic loads, particularly at the edges, leading to reduced fatigue and rupture strength, and existing solutions often require expensive materials or complex designs.
Innovation Solution
Introducing compressive stresses into the edges of the piston ring by rolling, which increases fatigue strength by reducing tensile stresses and preventing crack propagation, without the need for expensive materials or complex designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength of the material is increased to prevent ring cracks, then the rupture strength is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies local quality by introducing compressive stresses specifically at the edge zones of the piston ring where cracks typically initiate. Instead of increasing the strength of the entire ring material, the solution locally modifies the stress state at the critical edge regions through rolling treatment, thereby preventing crack formation without requiring expensive high-strength materials throughout the entire component.
Solution Approach 2:
The patent changes the physical parameter of stress distribution in the piston ring edge zones by applying rolling treatment. This process transforms the stress state from tensile (which promotes cracking) to compressive (which prevents cracking), thereby improving rupture strength without changing the base material composition or requiring costly material substitutions.
2Strength
If the thickness of the material is increased to prevent ring cracks, then the fatigue strength is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies local quality by concentrating the strengthening effect at the edge zones where cracks initiate, rather than increasing the thickness of the entire piston ring. The rolling treatment creates a localized compressive stress field at the edges, providing fatigue protection precisely where needed without adding overall complexity to the ring design or requiring thicker sections throughout.
3Strength
If compressive stresses are introduced by rolling, then the fatigue strength is increased by 30%, but additional manufacturing steps are required
Solution Approach 1:
The patent applies preliminary action by introducing compressive stresses through rolling treatment during the manufacturing process, before the piston ring is installed in the engine. This pre-establishes the protective compressive stress field in the edge zones, ensuring fatigue resistance from the outset without requiring additional maintenance or intervention during engine operation.
Solution Approach 2:
The patent changes the stress distribution parameter in the piston ring by applying rolling treatment, transforming the edge zones from tensile stress regions (prone to cracking) to compressive stress regions (resistant to cracking). This parameter change achieves a 30% increase in fatigue strength and can be integrated into existing manufacturing workflows.
4Strength
If expensive materials or complex designs are used to increase fatigue strength, then the rupture strength is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies local quality by targeting the edge zones of the piston ring for rolling treatment, where cracks typically initiate. This localized approach provides fatigue strength enhancement precisely where needed without requiring expensive materials for the entire component, thereby maintaining cost-effectiveness while achieving the desired strength improvement.
Solution Approach 2:
The patent changes the stress distribution parameter through rolling treatment, creating compressive stresses in the edge zones that prevent crack formation. This parameter modification achieves fatigue strength improvement without requiring expensive material substitutions or complex design changes, maintaining manufacturing simplicity and cost-effectiveness.
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 method achieves a 30% increase in fatigue strength and rupture strength of piston rings, effectively preventing crack propagation under alternating loads, while maintaining cost-effectiveness and simplicity in manufacturing.
Implementation Method 1
The piston ring comprises a plastically deformable material and has at least one edge between a running surface and a piston ring flank, compressive stresses being introduced into the edge between the running surface and the piston ring flank by rolling
Implementation Method 2
compressive stresses being introduced into the edge between the running surface and the piston ring flank by rolling
Data Source
Figure 1~3
Figure 4~5
AI summary
The present invention relates to a piston ring (2) with increased fatigue strength, made of a plastically deformable material. The piston ring (2) has a bearing surface (4) which is limited at the top by an upper bearing surface edge (3) and at the bottom by a lower bearing surface edge (1). Along at least one part of the circumference, compressive stresses are introduced to the upper bearing surface edge (3) and/or to the lower bearing surface edge (1), wherein said compressive stresses are produced by rolling.