CV Joint Grease Composition for Low-Temperature Stick-Slip Prevention
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Solution Overview
Problem
Conventional fixed type constant velocity universal joints experience stick slip and abnormal noises at low temperatures due to temporary lack of lubricity in extremely cold regions, leading to inefficiencies in power transmission systems.
Innovation Solution
The use of a grease composition containing 80% or more paraffinic mineral oil or a mixture of paraffinic mineral oil and synthetic hydrocarbon oil, with 3 to 8% thickener and 5 to 20% ester oil, along with track grooves formed as circular arcs and straight portions, to enhance lubricity and prevent stick slip and abnormal noises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional grease is used in extremely cold regions, then the universal joint can operate at low temperatures, but stick slip and abnormal noises occur due to temporary lack of lubricity
Solution Approach 1:
The patent changes the chemical composition parameters of the grease by specifying 80% or more paraffinic mineral oil or a mixture of paraffinic mineral oil and synthetic hydrocarbon oil, along with 3 to 8% thickener and 5 to 20% ester oil. This parameter change ensures the grease maintains appropriate viscosity and flowability at low temperatures, preventing stick slip and abnormal noises while maintaining reliable lubricity.
2Reliability
If grease viscosity is increased to prevent lubricity loss, then lubrication is improved, but grease flowability at low temperatures deteriorates
Solution Approach 1:
The patent uses a composite grease formulation combining multiple base oils (paraffinic mineral oil, synthetic hydrocarbon oil, and ester oil) with a thickener. The paraffinic mineral oil provides low-temperature flowability, the synthetic hydrocarbon oil enhances viscosity stability, and the ester oil improves lubricity. This composite material approach achieves both good lubricity and maintained flowability at low temperatures.
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 proposed solution ensures the flowability and viscosity of the grease at low temperatures, preventing stick slip and abnormal noises, while maintaining durability and cost-effectiveness in power transmission systems.
Implementation Method 1
the grease contains 80% by mass or more of paraffinic mineral oil or a mixture of paraffinic mineral oil and synthetic hydrocarbon oil with respect to the total mass of a lubricant component contained as base oil
Implementation Method 2
grease having a friction coefficient of 0.13 or less is applied to track grooves, thereby preventing hammering sound from occurring
Data Source
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AI summary
Provided is a fixed type constant velocity universal joint which can prevent stick slip from occurring due to lack of lubricity, and prevent abnormal noises from occurring at low temperatures, even during use in an extremely cold region. The fixed type constant velocity universal joint which has grease enclosed therein and is provided with an outer joint member 23 having an inner surface in which a plurality of track grooves 22 are formed, an inner joint member 26 having an outer circumferential surface in which a plurality of track grooves 25 are formed, a plurality of balls 27 for transmitting torque provided between the track grooves 22 of the outer joint member 23 and the track grooves 25 of the inner joint member 26, and a cage 28 for retaining the balls 27, in which the grease contains 80% by mass or more of paraffinic mineral oil or a mixture of paraffinic mineral oil and synthetic hydrocarbon oil with respect to the total mass of a lubricant component contained as base oil, the paraffinic mineral oil accounts for 70% by mass or more of the total mass of the lubricant component, and the grease contains 3 to 8% by mass of a thickener with respect to the total mass of the grease, so that the grease prevents abnormal noises from occurring at low temperatures.