Large-Shaft Bearing Surface Roughness for Seizure Prevention
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Solution Overview
Problem
Existing bearing devices for ships face challenges in inhibiting frictional resistance and seizure between shaft and bearing members, particularly in high-load environments, while avoiding the mixing of impurities and increased costs associated with surface treatments, and are not effective for rotating shafts.
Innovation Solution
A bearing device with a shaft member and bearing member optimized by controlling the arithmetic mean roughness and protruding peak height of their surfaces, along with a lubricating oil system that maintains a fluid lubrication state, eliminating the need for surface coatings and reducing frictional resistance and seizure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nitrogen-containing amorphous carbon film is formed on the bearing member surface, then frictional resistance and seizure are reduced, but impurities are mixed into the lubricating oil and cost increases
Solution Approach 1:
The patent removes the surface film coating from the bearing member, extracting the problematic element (film) that causes impurity mixing while maintaining the essential function of friction reduction through optimized surface roughness control of the shaft member alone
Solution Approach 2:
The patent changes the surface roughness parameters of the shaft member (arithmetic mean roughness Ra and protruding peak height Rpk) to specific ranges that enable the shaft surface to reduce friction without requiring a coating film, thereby preventing impurity generation while maintaining reliability
2Reliability
If a nitrogen-containing amorphous carbon film is formed on the bearing member surface, then frictional resistance and seizure are reduced, but capital investment and cost increase
Solution Approach 1:
The patent eliminates the expensive surface film coating process from the bearing member, removing the capital investment and cost burden while achieving the same friction reduction effect through simpler shaft member surface roughness control
Solution Approach 2:
The patent replaces the expensive, complex surface film coating with a simpler, more economical approach using controlled surface roughness of the shaft member, which achieves friction reduction without requiring costly materials or manufacturing processes
3Reliability
If the technique from Patent Document 2 is applied to a rotating shaft bearing device, then friction may be reduced, but the technique is designed for reciprocating motion and may not be effective for rotation
Solution Approach 1:
The patent adapts the surface parameters (arithmetic mean roughness Ra and protruding peak height Rpk) to specific ranges suitable for rotating shaft conditions, transforming the approach from reciprocating motion design to rotational motion optimization
Solution Approach 2:
The patent applies specific surface roughness characteristics to the shaft member surface that are tailored for rotational bearing conditions, creating local surface properties optimized for the specific operating conditions of rotating shafts rather than general reciprocating motion
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 optimized bearing device effectively inhibits frictional resistance and seizure while preventing the mixing of impurities and reducing costs, maintaining a fluid lubrication state and ensuring efficient operation of rotating shafts.
Implementation Method 1
lubricating oil is supplied to a gap between the shaft member and the bearing member. The lubricating oil forms an oil film between the shaft member and the bearing member to reduce frictional resistance between these members
Data Source
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AI summary
A bearing device includes: a shaft member having a shaft diameter of greater than or equal to 180 mm; a bearing member which slidably supports an outer peripheral face of the shaft member; and a lubricating oil which is supplied to a gap between the outer peripheral face of the shaft member and an inner peripheral face of the bearing member and forms an oil film in the gap, wherein an arithmetic mean roughness Ra1 of the outer peripheral face of the shaft member is greater than or equal to 0.05 µm and less than or equal to 0.30 µm, and a protruding peak height Rpki of the outer peripheral face is greater than or equal to 0.04 µm and less than or equal to 0.34 µm.