Plain Bearing Lubricative Surface Layer Friction Reduction
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Solution Overview
Problem
Plain bearings in internal combustion engines face challenges with high friction coefficients and reduced lubricant oil films due to increased speed and power demands, leading to potential seizure and fatigue issues, especially when using low-viscosity lubricants, which exacerbate metal-to-metal contact and heat generation.
Innovation Solution
A plain bearing design featuring an aluminum-base bearing alloy with a lubricative surface layer containing a solid lubricant, such as molybdenum disulfide, applied via shot blasting to achieve a low coefficient of friction while maintaining fatigue resistance, with a Vickers hardness between 40 and 160 and a surface layer thickness of up to 10 μm, ensuring effective lubrication and preventing surface roughening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a low-viscosity lubricant oil is used to reduce shearing resistance, then fuel consumption is reduced, but the lubricant oil film becomes thinner thereby increasing metal-to-metal contact portions
Solution Approach 1:
The patent applies a solid lubricant coating specifically on the surface layer of the bearing alloy, creating a localized lubricative zone where metal-to-metal contact occurs. This allows the use of low-viscosity lubricant oil in the bulk while maintaining a protective lubricating film at the critical contact surface, thus resolving the contradiction between reduced fuel consumption and maintained anti-seizure property.
Solution Approach 2:
The patent creates a composite structure by combining aluminum-base bearing alloy with a solid lubricant coating layer. This composite material integrates the load-bearing capacity of the aluminum alloy with the low-friction properties of the solid lubricant, enabling both low fuel consumption through reduced friction and high reliability through prevented metal-to-metal adhesion.
2Object-generated harmful factors
If the coefficient of friction is reduced by adding solid lubricant to bearing alloy, then heat generation is reduced, but the bearing alloy strength may be compromised
Solution Approach 1:
The patent segments the bearing structure into two distinct functional layers: the aluminum-base bearing alloy substrate that provides mechanical strength and load-bearing capacity, and the solid lubricant coating layer that provides low-friction properties and reduces heat generation. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The patent creates a composite structure by combining aluminum-base bearing alloy with a solid lubricant coating layer. This composite material integrates the load-bearing capacity of the aluminum alloy with the low-friction properties of the solid lubricant, enabling both low fuel consumption through reduced friction and high reliability through prevented metal-to-metal adhesion.
3Ease of manufacture
If coating method is used to apply solid lubricant, then application is simple, but bonding strength is inferior and binder resin may reduce friction reducing effect
Solution Approach 1:
The patent removes the binder resin component from the solid lubricant application, using pure solid lubricant material applied through shot blasting. This extraction of the problematic binder resin eliminates the issue of reduced friction effect while maintaining strong bonding through mechanical embedding of the solid lubricant particles into the bearing surface.
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 significantly reduces frictional resistance and heat generation, enhancing anti-seizure and fatigue resistance properties by maintaining a stable lubricant film and preventing surface deterioration, thus ensuring reliable operation under high-speed and high-load conditions.
Implementation Method 1
the frictional resistance between a mating shaft and a plain bearing is high, so that the plain bearings might not contribute to lower fuel consumption and friction heat is generated
Implementation Method 2
a fine powder of molybdenum disulfide (MoS2), as a solid lubricant, is shot to collide against the piston so as to penetrate into the surface layer of the piston
Data Source
AI summary
Disclosed is a plain bearing for internal combustion engines, in which a back metal layer is lined with a bearing alloy layer made of an aluminum-base bearing alloy which has a Vickers hardness (Hv) of from not less than 40 to not more than 160. The bearing alloy layer includes a lubricative surface layer which has a thickness of not more than 10 μm and contains a solid lubricant. The maximum concentration of an element contained in the solid lubricant is not less than 5 mass %.