Oil-Hole Link Component Carbon Gradient for Bending Stress Resistance
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Solution Overview
Problem
The link components of internal combustion engines with oil holes are prone to damage due to concentrated bending stress, and existing high-cost solutions involving high-temperature tempering and multiple additive elements are inefficient.
Innovation Solution
A link component with an oil hole featuring an inclined surface on the crankshaft side and a carbon concentration of 0.7 wt % to 0.9 wt % for increased resistance, and a carbon concentration of 0.5 wt % or more on other surfaces to enhance yield strength, without the need for high-temperature tempering or multiple additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If general carburizing and quenching is applied to the entire link component, then the surface hardness is increased, but the oil-hole parts still cannot withstand high bending stress due to stress concentration
Solution Approach 1:
The patent applies different carbon concentration ranges to different regions of the link component. The oil-hole parts have a carbon concentration of 0.7-0.9 wt%, while other parts have 0.5 wt% or more. This local differentiation allows the oil-hole regions to achieve higher strength and toughness to withstand bending stress concentration, while other regions maintain adequate hardness.
Solution Approach 2:
The patent changes the carbon concentration parameter spatially within the component. By controlling the carbon concentration to be higher (0.7-0.9 wt%) in the oil-hole regions compared to other areas (0.5 wt% or more), the material properties are optimized for the specific stress conditions at each location, resolving the contradiction between general hardness and localized strength.
2Strength
If high-temperature tempering and multiple additive elements are used to increase bending-fatigue resistance, then the link component achieves high hardness and toughness, but the production cost increases significantly
Solution Approach 1:
Instead of applying expensive high-temperature tempering and multiple additives throughout the entire component, the patent uses selective carbon concentration control (0.7-0.9 wt% in oil-hole parts vs. 0.5 wt% or more elsewhere) to achieve the required bending-fatigue resistance only where needed, reducing overall material cost and simplifying the manufacturing process.
Solution Approach 2:
The patent replaces the expensive combination of high-temperature tempering and multiple additive elements with a controlled carbon concentration gradient. This parameter change achieves comparable or superior bending-fatigue resistance through compositional control rather than costly processing and alloying.
3Strength
If the carbon concentration is increased uniformly throughout the link component, then the yield strength is improved, but the risk of cementite formation increases which may cause damage
Solution Approach 1:
The patent applies different carbon concentration ranges to different regions: 0.7-0.9 wt% in oil-hole parts where high strength is needed but cementite must be avoided, and 0.5 wt% or more in other parts. This localized approach achieves yield strength improvement while suppressing harmful cementite formation in the critical oil-hole regions.
Solution Approach 2:
By spatially varying the carbon concentration parameter, the patent optimizes the balance between yield strength and cementite formation risk. The controlled carbon range of 0.7-0.9 wt% in oil-hole parts provides sufficient strength while staying below the threshold for excessive cementite formation.
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 solution effectively increases the initial crack strength and prevents damage by concentrating carbon on the inclined surface, reducing production costs and eliminating the risk of cementite formation, thereby enhancing the durability of the link components.
Implementation Method 1
The carburizing and the quenching refer to a technology for increasing bending-fatigue resistance of steel components by forming their surfaces into dense martensitic structures, specifically, by subjecting these surfaces to carbon impregnation and rapid cooling.
Implementation Method 2
a surface other than the oil hole has a carbon concentration of 0.5 wt % or more. The inclined surface has a carbon concentration within a range of 0.7 wt % or more and 0.9 wt % or less
Data Source
AI summary
A link component (150) with an oil hole (150E) is attached to a crankshaft (106) of an internal combustion engine (E), and the oil hole (150E) allows communication from an outside to the crankshaft (106) side. The oil hole (150E) has an inclined surface (150F) along an opening rim on the crankshaft (106) side. A surface other than the oil hole (150E) has a carbon concentration of 0.5 wt % or more. The inclined surface (150F) has a carbon concentration within a range of 0.7 wt % or more and 0.9 wt % or less. Production cost is suppressed, and at the same time, damage is prevented by increasing resistance of the oil-hole part on which stress is liable to concentrate.