Grease Composition for On-Vehicle Speed Reducer
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Solution Overview
Problem
Conventional greases for on-vehicle electric component speed reducers face challenges in maintaining adhesiveness and low-temperature properties under high-speed conditions, with viscosity increasers causing dispersion and decreased performance at low temperatures.
Innovation Solution
A grease composition using a mixture of specific diurea compounds as a thickener and a mixed oil of PAO and mineral oil with specific kinematic viscosity and pour point ranges, optimizing penetration to balance adhesiveness and low-temperature properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a viscosity increaser is included in grease to improve adhesiveness, then adhesiveness under high-speed condition is improved, but low-temperature property decreases due to increased viscosity in low-temperature environment
Solution Approach 1:
The invention changes the chemical composition parameters of the base oil, specifically using a mixed oil comprising poly-α-olefin and mineral oil in a controlled ratio range (30:70 to 70:30 by mass). This parameter change allows the grease to achieve both high-temperature adhesiveness and low-temperature fluidity without requiring viscosity increasers that would harm low-temperature performance.
Solution Approach 2:
The invention uses a composite base oil system combining poly-α-olefin and mineral oil in specific proportions. This composite material approach leverages the complementary properties of both oils: poly-α-olefin provides high-temperature stability and adhesiveness, while mineral oil contributes to low-temperature fluidity, achieving a balance that single-component oils cannot provide.
2Ease of operation
If the kinematic viscosity of base oil is reduced or penetration of grease is increased to improve low-temperature property, then low-temperature property is improved, but adhesiveness under high-speed condition decreases
Solution Approach 1:
The invention optimizes the kinematic viscosity parameter of the base oil within a specific range (10 to 50 mm²/s at 40°C) and controls the penetration value (220 to 300 at 25°C). These parameter changes are achieved through the controlled mixing ratio of poly-α-olefin and mineral oil, enabling the grease to simultaneously achieve good low-temperature property and sufficient adhesiveness under high-speed conditions.
Solution Approach 2:
The composite base oil system of poly-α-olefin and mineral oil in controlled ratios provides a synergistic effect where the mixture as a whole exhibits properties superior to the individual components. The composite material maintains appropriate viscosity and penetration values that balance both low-temperature operability and high-speed adhesiveness.
3Ease of manufacture
If a single type of diurea compound is used as thickener, then manufacturing simplicity is maintained, but the balance between adhesiveness and low-temperature property cannot be achieved
Solution Approach 1:
The invention uses a composite thickener system combining aliphatic diurea and aromatic diurea compounds in a controlled mass ratio (1:4 to 4:1). This composite approach creates a synergistic effect where the two thickener types work together to provide both adequate adhesiveness and good low-temperature property, achieving a performance balance that single thickener types cannot accomplish.
Solution Approach 2:
The invention optimizes the thickener content parameter within the range of 5 to 30 mass% and controls the ratio of aliphatic to aromatic diurea compounds. These parameter changes enable the grease to achieve the desired balance between adhesiveness and low-temperature property while maintaining reasonable manufacturing complexity.
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 composition achieves improved durability and extended life of speed reducers by maintaining adhesiveness and low-temperature performance, reducing starting voltage, and providing excellent heat resistance.
Implementation Method 1
The thickener contains a diurea compound... a mixture of specific diurea compounds as a thickener
Implementation Method 2
a mixed oil of PAO and mineral oil that has a kinematic viscosity and a pour point within specific ranges
Data Source
AI summary
The invention provides a grease composition for a speed reducer part of an on-vehicle electric component, the grease composition containing a base oil and a thickener, wherein the base oil is poly-α-olefin or a mixed oil of poly-α-olefin and mineral oil having a kinematic viscosity of 4 to 19 mm2/s at 100°C and a pour point of -30°C or lower, the thickener is a mixture of a diurea compound expressed by formula (1) and a diurea compound expressed by formula (2) R1-NHCONH-R2-NHCONH-R1 (1) R3-NHCONH-R2-NHCONH-R3 (2) wherein R1 is a straight-chain alkyl group having 8 or 18 carbon atoms, R2 is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R3 is an aryl group having 6 to 7 carbon atoms, and a penetration of the grease composition is 220 to 280.