Variable Transmission Traction Fluid Low Temperature Flow
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Solution Overview
Problem
Conventional lubricants for infinitely variable transmissions face challenges in achieving a balance between good low temperature flow properties and high elastohydrodynamic (EHD) shear strength, with dimethylsilicone fluids previously limited by poor hydrocarbon solubility and compatibility issues.
Innovation Solution
The use of simple dimethylsilicone fluids with a viscosity of less than 20 centistokes, specifically blended with a perhydro dimer of alpha-methyl styrene, enhances low temperature performance without compromising shear strength, allowing for the formulation of fully-formulated traction fluids with improved thermal conductivity and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cycloaliphatic hydrocarbons are used as traction fluid, then high EHD shear strength is achieved, but low temperature flow properties deteriorate
Solution Approach 1:
The patent combines cycloaliphatic hydrocarbon (providing high EHD shear strength) with dimethylsilicone fluid (providing excellent low temperature flow properties) to create a composite traction fluid that achieves both high shear strength and good low temperature performance simultaneously, resolving the contradiction between these two opposing requirements
Solution Approach 2:
The patent carefully controls the viscosity parameter of the dimethylsilicone fluid component (keeping it below 20 centistokes at 77°F) and optimizes the blending ratio to maintain high EHD shear strength while improving low temperature flow properties, demonstrating parameter optimization to resolve the contradiction
2Ease of operation
If fluids with good low temperature properties are incorporated to improve low temperature performance, then low temperature flow properties are enhanced, but shear strength deteriorates
Solution Approach 1:
The patent selects dimethylsilicone fluid with specifically controlled viscosity parameters (less than 20 centistokes at 77°F) and optimizes its concentration in the blend to improve low temperature flow properties while maintaining adequate shear strength, demonstrating precise parameter control to avoid the typical trade-off
3Ease of operation
If low-viscosity dimethylsilicone fluids are used to improve low temperature flow, then low temperature viscometrics are enhanced, but volatility and flash/fire points may be compromised
Solution Approach 1:
The patent creates a composite fluid system where dimethylsilicone fluid (low viscosity, excellent low temperature properties) is blended with cycloaliphatic hydrocarbon (high flash point, low volatility). The hydrocarbon component compensates for the volatility concerns of the silicone fluid while the silicone component provides the low temperature performance, thus resolving the contradiction through synergistic combination
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
This approach results in traction fluids with improved low temperature viscometrics and maintained high temperature shear strength, enabling effective torque transmission in infinitely variable transmissions without significant volatility or viscosity compromise.
Implementation Method 1
simple low-viscosity dimethylsilicone fluids can accomplish the desired balance of these properties
Implementation Method 2
high elastohydrodynamic (EHD) shear strength
Implementation Method 3
The fluid is required to exhibit high pressure and high shear conditions found I the area of contact between the plate or roller elements which are separated by a thin film of the fluid
Implementation Method 4
The long chain molecules of the traction fluid interlock with one another when the fluid is compressed and becomes highly viscous under pressure
Data Source
AI summary
The present invention utilizes simple dimethylsilicone fluids of the proper viscosity/molecular weight added to modify the low temperature properties of polycyclic hydrocarbons. One preferred embodiment of a polycyclic hydrocarbon is a perhydro dimer of alpha-methyl styrene. Addition of the dimethylsilicone fluid to the perhydo dimer of alpha-methyl styrene improves the low temperature performance without degrading the requisite low shear stress shear strength properties. Low viscosity dimethylsilicone lubricating fluids combined with polycyclic hydrocarbons are suitable for use in infinitely variable transmissions providing good low temperature flow properties and high shear strength at high temperature and low contact stress conditions.