Oil-Impregnated Bushing Viscosity for High-Temperature Lubricity
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Solution Overview
Problem
Oil-free chains experience lubricity loss and reduced abrasion resistance at high temperatures due to decreased kinematic viscosity of PFPE, leading to oil film discontinuity and shortened lifespan.
Innovation Solution
Impregnating bushings with lubricating oil having a kinematic viscosity of 720 mm²/s or more at 40°C, using perfluoropolyether as a major ingredient, to maintain lubricity and prevent oil film discontinuity even at high temperatures up to 250°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If PFPE is used as lubricating oil for high-temperature operation, then heat resistance is improved, but kinematic viscosity decreases at high temperature causing oil film discontinuity
Solution Approach 1:
The patent changes the kinematic viscosity parameter of the lubricating oil to 720 mm²/s or more at 40°C, which is significantly higher than conventional PFPE. This parameter change ensures that even when viscosity decreases at high temperatures, the oil maintains sufficient film thickness and continuous lubrication, resolving the contradiction between heat resistance and lubricity retention.
2Reliability
If lubricating oil with high kinematic viscosity is used, then lubricity is maintained at high temperature, but oil may flow out excessively from the bushing pores
Solution Approach 1:
The patent utilizes the porous structure of the sintered metal bushing to control oil retention. The pores act as reservoirs that hold the high-viscosity lubricating oil, allowing it to be released gradually during operation. This prevents excessive oil flow out while maintaining continuous lubrication, resolving the contradiction between lubricity and oil loss.
3Ease of operation
If conventional PFPE is impregnated in bushing, then lubrication performance is achieved, but abrasion elongation-resistant life is shortened at high temperature
Solution Approach 1:
The patent changes the kinematic viscosity parameter to 720 mm²/s or more at 40°C, ensuring sufficient lubrication film thickness during high-temperature operation. This extended lubrication capability directly increases the abrasion elongation-resistant life of the chain, resolving the contradiction between lubrication performance and component lifespan.
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
Ensures continuous lubrication and extended abrasion-resistant life of oil-free chains by maintaining sufficient kinematic viscosity under high-temperature conditions without excessive oil flow, thereby enhancing the chain's performance and longevity.
Implementation Method 1
the lubricating oil for impregnation of the oil-impregnated bushing oozes out
Implementation Method 2
oil film discontinuity arises
Data Source
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AI summary
An oil-impregnated bushing in which oil film discontinuity does not arise at an inner circumferential face and which has a favorable abrasion resistant life, an oil-free chain comprising the oil-impregnated bushing, and a method for manufacturing the oil-impregnated bushing are provided. The oil-free chain 1 is obtained by connecting a pair of inner link plates 2, 2, which are connected by oil-impregnated bushings 3, 3, and a pair of outer link plates 4, 4, which are connected by pins 5, 5 inserted into adjacent oil-impregnated bushings 3, 3 of adjacent inner link plates 2, 2, alternately. The oil-impregnated bushing 3 is obtained by impregnating a bushing made of a metal sintered body with perfluoropolyether having a kinematic viscosity at 40 °C equal to or higher than 350 mm 2 /s. The bushing is impregnated with perfluoropolyether having a kinematic viscosity corresponding to the operating temperature of the oil-free chain 1.