Cylinder Bore Surface Roughness for Tribological Optimization
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Solution Overview
Problem
Current internal combustion engine cylinder bore surface treatments, which vary roughness values to optimize lubrication and reduce wear, often result in excessive roughness at top and bottom dead center areas, affecting piston movement smoothness and overall engine performance.
Innovation Solution
A cylinder bore design with different roughness values on pressure and counter-pressure sides, adjusted based on piston speed and lateral forces, to optimize lubrication and reduce wear, featuring a smoother surface at lower regions and increased roughness at high-force areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher roughness value Rvk is provided at top and bottom dead center portions to increase oil storage and reduce wear during mixed friction, then lubrication is improved, but piston movement smoothness is adversely affected
Solution Approach 1:
The patent applies different roughness values to different regions of the cylinder bore surface. Specifically, the first longitudinal region (where lateral forces are highest) has a higher roughness value Rvk1 for oil storage, while the second longitudinal region has a lower roughness value Rvk2 for smooth piston movement. This local differentiation resolves the contradiction by optimizing each region for its specific functional requirements.
2Reliability
If roughness values are varied over the bore surface to optimize lubrication at dead center portions, then wear is reduced, but device complexity increases
Solution Approach 1:
The cylinder bore surface is segmented into distinct longitudinal regions with different roughness characteristics. The first longitudinal region extends from the piston crown toward the midpoint with roughness Rvk1, while the second longitudinal region extends from the piston crown toward the opposite dead center with roughness Rvk2. This segmentation allows optimized wear protection in high-stress areas while maintaining simpler surface treatment overall.
3Loss of energy
If lower roughness value is provided in intermediate portion to enable hydrodynamic lubrication, then friction is reduced, but oil storage capacity is decreased
Solution Approach 1:
The patent optimizes oil storage and friction reduction by assigning different roughness values to different longitudinal regions. The first longitudinal region with higher roughness Rvk1 provides oil storage capacity where lateral forces are highest, while the second longitudinal region with lower roughness Rvk2 facilitates hydrodynamic lubrication where piston speed is greatest, thereby reducing friction losses.
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
This approach enhances oil storage and lubrication during high lateral forces, reduces wear and friction, and maintains smooth piston movement by tailoring surface roughness to kinematic conditions, thereby improving engine efficiency and longevity.
Implementation Method 1
The roughness value Rvk may be mainly responsible for the quantity of the oil retained in the indentations in order to lubricate this tribological system adequately
Implementation Method 2
during a piston stoppage, that is to say, in the top and bottom dead center, the hydrodynamic behavior is cancelled and a mixed friction occurs
Implementation Method 3
In the intermediate portion in which the piston has the greatest relative speed with respect to the bore surface, however, the roughness value Rvk may be reduced as a result of the hydrodynamic behavior
Data Source
AI summary
The invention relates to a cylinder bore and a method. The cylinder bore is configured to receive a piston for reciprocating movement therein and has a pressure side and a counter-pressure side. The cylinder bore includes a bore surface having a first roughness value in a first longitudinal region on the pressure side and a second roughness value different from the first roughness value in the first longitudinal region on the counter-pressure side.