Cylinder Liner Fire Ring Structure for Fatigue Crack Reduction
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Solution Overview
Problem
Cylinder liners in combustion engines face issues with reduced stiffness and increased fatigue cracks due to large scraper rings, leading to pressure differences and material strength deterioration.
Innovation Solution
A cylinder liner design with a recess accommodating a ring-shaped element, where the inner diameter of the upper wall portion is larger than the bottom, minimizing pressure differences and enhancing stiffness by reducing the recess depth and optimizing the ring's dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large scraper ring is used to ensure proper piston functionality, then the scraping function is improved, but the material thickness of the cylinder liner is reduced, resulting in reduced stiffness and increased fatigue cracks
Solution Approach 1:
The scraper ring is divided into two separate functional elements: a fire ring for scraping carbon deposits and a separate compression ring for maintaining compression. This segmentation allows each ring to be optimized for its specific function while reducing the overall radial height required in the cylinder liner, thereby preserving material thickness and structural strength.
Solution Approach 2:
The invention transitions from a single large-diameter scraper ring to multiple smaller-diameter rings stacked axially. By moving the scraping function to a smaller radial dimension and distributing it across multiple axial layers, the design maintains effective scraping while preserving cylinder liner stiffness and reducing fatigue stress concentrations.
2Ease of operation
If a large scraper ring is used to improve piston functionality, then the scraping capability is enhanced, but pressure differences between the combustion chamber and piston upper part increase, deteriorating material strength
Solution Approach 1:
The fire ring is separated from the compression ring, allowing the fire ring to be positioned at an optimal radial height for scraping while the compression ring maintains sealing. This separation enables pressure equalization between the combustion chamber and piston upper part, reducing harmful pressure differences that would otherwise deteriorate material strength.
Solution Approach 2:
The invention changes the radial dimension parameter of the scraper ring, reducing its radial height from a large single ring to a smaller fire ring positioned at an optimized height. This parameter change reduces the volume of trapped pressure differences while maintaining effective scraping functionality.
3Ease of operation
If the recess depth is increased to accommodate the ring-shaped element, then the scraping function is improved, but the stiffness of the cylinder liner is reduced
Solution Approach 1:
The scraping function is segmented into a smaller fire ring that requires less radial depth in the cylinder liner. By reducing the radial height of the fire ring and positioning it at an optimized height, the recess depth is minimized while maintaining effective scraping, thereby preserving cylinder liner stiffness.
Solution Approach 2:
The invention optimizes the radial height parameter of the ring-shaped element, reducing it from a large scraper ring to a compact fire ring. This parameter optimization allows the recess to be shallower while maintaining scraping effectiveness, thus preserving the structural stiffness of the cylinder liner.
Data Source
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AI summary
The present invention pertains to a cylinder liner for a cylinder of a combustion engine as well as a combustion engine comprising at least one cylinder with a corresponding cylinder liner, in particular to reduce pressure differences between a combustion chamber and an upper part of a piston and/or to improve stiffness and fatigue strength of the cylinder liner. Accordingly, a cylinder liner (10) for a cylinder of a combustion engine is suggested, which comprises a longitudinally extending wall, wherein an inner diameter of the wall defines a bore (12) configured for receiving a piston and wherein the wall comprises a recess (14) facing the bore (12) and accommodating a ring-shaped element (16) extending into the bore (12) and beyond the wall in a radially inward direction. An inner diameter (20) of an upper wall portion (18) extending from the recess (14) to a combustion region end portion of the cylinder liner (10) is larger than an inner diameter (24) of a bottom wall portion (22) extending from the recess (14) to an opposing end portion of the cylinder liner (10).