Grease Composition for Constant Velocity Joint Low-Temperature Resistance
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Solution Overview
Problem
Existing grease compositions for constant velocity joints fail to adequately reduce variation in rotational resistance at low temperatures, leading to stick-slip sounds and compromised riding comfort in extreme cold conditions.
Innovation Solution
A grease composition comprising a diurea thickening agent, synthetic ester oil, mineral or synthetic hydrocarbon oil, molybdenum dialkyldithiocarbamate, molybdenum disulfide, polytetrafluoroethylene, and zinc dithiophosphate, which optimizes fluidity, viscosity, and lubricity to minimize rotational resistance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional grease compositions (mineral oil base with molybdenum compound) are used, then basic lubrication is provided, but variation in rotational resistance at low temperature cannot be sufficiently reduced
Solution Approach 1:
The patent uses a composite grease composition combining synthetic ester oil and mineral oil base oils with multiple additive packages including molybdenum compounds, zinc dithiophosphate, and extreme pressure agents. This composite approach creates synergistic effects that reduce rotational resistance variation at low temperatures better than conventional single-base greases
Solution Approach 2:
The patent modifies the chemical composition parameters of the grease by specifying precise ranges for base oil viscosity (10-100 cSt at 40°C), synthetic ester oil content (10-50%), and additive concentrations. These parameter optimizations ensure the grease maintains stable lubrication properties across extreme temperature variations
2Power
If high-power engines are used to improve car performance, then power transmission capability is enhanced, but constant velocity joints are exposed to greater stresses and severer lubrication conditions
Solution Approach 1:
The grease composition includes extreme pressure additives (sulfur compounds, phosphorus compounds) and anti-wear agents that form protective films on metal surfaces in advance. This beforehand cushioning prevents severe wear and maintains lubrication stability under the high stresses generated by high-power engines
Solution Approach 2:
The multi-component grease formulation combines base oils with different viscosity characteristics and multiple additive systems that work synergistically to handle both high power transmission loads and maintain lubrication stability under severe operating conditions
3Ease of operation
If steering wheel is fully turned to achieve smooth power transmission, then constant velocity joint operates at extreme crossing angles, but rotational resistance variation increases due to frictional resistance differences among parts
Solution Approach 1:
The patent optimizes the grease viscosity parameter (10-100 cSt at 40°C) and base oil composition to ensure the grease maintains appropriate fluidity and film strength at extreme crossing angles. This parameter optimization reduces frictional resistance differences among joint parts during full steering operations
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 grease composition effectively reduces rotational resistance variations at low temperatures, enhancing the performance and comfort of constant velocity joints in extreme cold conditions by optimizing fluidity, viscosity, and lubricity.
Implementation Method 1
a diurea thickening agent having the following formula (1)
Implementation Method 2
a molybdenum dialkyldithiocarbamate... molybdenum disulfide
Implementation Method 3
a polytetrafluoroethylene
Implementation Method 4
a zinc dithiophosphate compound
Implementation Method 5
a synthetic ester oil... a flow point of the synthetic ester oil, the component (b), is not higher than −40° C.
Data Source
AI summary
The invention provides a grease composition for constant velocity joint containing the components (a) to (g) below and a constant velocity joint containing said composition. (a) a diurea thickening agent having the following formula (1):R1NH—CO—NH—C6H4-p-CH2—C6H4-p-NH—CO—NHR2 (1)wherein R1 and R2 may be the same or different and represent C8-C20 alkyl groups, (b) an ester synthetic oil, (c) a mineral oil and/or a synthetic hydrocarbon oil, (d) a molybdenum dialkyldithiocarbamate, (e) molybdenum disulfide, (f) a polytetrafluoroethylene, and (g) a zinc dithiophosphate compound. The grease composition of the invention reduces variations in rotational resistance of the constant velocity joint at a low temperature.