Engine Valve Raised Ring and Dimple for Fatigue Resistance
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Solution Overview
Problem
Modern heavy-duty diesel engines face challenges with high and low cycle fatigue, as well as valve recession in engine valves due to increased pressures and temperatures, leading to maintenance and downtime issues.
Innovation Solution
The engine valve design incorporates a stem, a head with an outer lip surface, a seating surface, and a combustion surface featuring a convex arcuate surface forming a raised ring and a concave arcuate surface forming a dimple, which reduces stress and contact pressure, thereby enhancing durability and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If engine displacement is decreased or engine output is increased to meet competitive market demands, then power density and cost competitiveness are improved, but pressures and temperatures inside the cylinder increase, leading to greater demands on valves and increased fatigue problems
Solution Approach 1:
The patent applies local quality by modifying specific regions of the valve head (combustion surface) with raised rings and dimples while keeping other parts unchanged. These localized geometric modifications create areas of altered stress distribution that specifically address fatigue problems in high-stress zones without changing the overall valve design or requiring material changes throughout the entire component.
Solution Approach 2:
The patent employs curvature principles by introducing raised rings and dimples with specific radii of curvature on the combustion surface. These curved geometric features redistribute stress through their arcuate shapes, creating smoother stress transitions and reducing concentration points that would otherwise lead to fatigue failure under increased cylinder pressures and temperatures.
2Ease of manufacture
If conventional valve designs are used under increased cylinder pressures and temperatures, then manufacturing simplicity is maintained, but valve recession and fatigue problems increase, necessitating maintenance and causing downtime
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the combustion surface through raised rings and dimples with specific dimensions, radii, and positions. These parameter modifications alter the stress distribution characteristics and contact pressure patterns, enabling the valve to withstand harsher operating conditions and extend service life without fundamentally changing the manufacturing process or requiring complex multi-step production methods.
3Reliability
If valve geometry is modified to reduce stress and contact pressure, then fatigue and recession resistance is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the combustion surface into distinct geometric zones featuring raised rings and dimples with specific dimensions and positions. This segmented approach allows each feature to address specific stress concentration areas independently, providing targeted fatigue resistance while maintaining a systematic and manufacturable design that doesn't overly complicate the overall valve structure.
Data Source
AI summary
An engine valve includes a stem, a head comprising an outer lip surface, a seating surface extending from the outer lip surface toward the stem, and a combustion surface extending from the outer lip surface on the opposite side of the head as compared to the seating surface. The combustion surface includes a first convex arcuate surface spaced away from the outer lip surface, at least partially forming a raised ring, and a first concave arcuate surface spaced away from the outer lip surface, at least partially forming a dimple.