Two-Phase Lubricating Oil Composition for Wide Temperature Operation
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Solution Overview
Problem
Lubricating oils face challenges in maintaining viscosity across a wide range of temperatures, with low-viscosity oils losing film at high temperatures and high-viscosity oils experiencing churning losses and pump issues at low temperatures, making it difficult to find a single oil that functions effectively in both low- and high-temperature environments.
Innovation Solution
A two-phase lubricating oil composition comprising a low-viscosity hydrocarbon, a high-viscosity polyalkylene glycol, and a control aliphatic ester, where the oxygen/carbon weight ratio of the ester influences the mixing behavior, allowing for controlled separation temperature and maintained kinematic viscosity across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a low-viscosity lubricating oil is used, then the viscosity at low temperatures is low (reducing churning losses and improving pump feed), but the viscosity at high temperatures becomes too low (causing oil film loss and breakdown)
Solution Approach 1:
The lubricating oil is divided into two distinct phases: a low-viscosity hydrocarbon phase (5-500 cSt at 40°C) that remains liquid at low temperatures and provides good pumpability, and a high-viscosity polyalkylene glycol phase (>500 cSt at 40°C) that provides film strength at high temperatures. The phases separate at low temperatures but mix at high temperatures, providing temperature-dependent viscosity control.
Solution Approach 2:
The invention uses a phase separation temperature (Tsep) between -50°C and 100°C as a critical parameter to control the transition between single-phase and two-phase states. By adjusting Tsep through selecting appropriate hydrocarbon/PAG combinations and ratios, the system achieves low viscosity below Tsep (good pumpability) and high viscosity above Tsep (good film stability).
2Reliability
If a high-viscosity lubricating oil is used, then the viscosity at high temperatures is high (maintaining oil film), but the viscosity at low temperatures becomes too high (increasing churning losses and preventing pump feed)
Solution Approach 1:
The system dynamically adjusts its viscosity characteristics based on temperature. Below the phase separation temperature, the system exists as a single high-viscosity phase suitable for high-temperature film stability. Above Tsep, it transitions to a two-phase system where the low-viscosity hydrocarbon separates out, dramatically reducing overall viscosity for improved pumpability at low temperatures.
3Adaptability or versatility
If a single lubricating oil is used to cover wide temperature ranges, then it may function in both low and high temperatures, but it is difficult to maintain the necessary viscosity characteristics across the entire temperature range
Solution Approach 1:
The invention creates a composite lubricating oil system combining two immiscible or partially miscible lubricants with vastly different viscosity-temperature characteristics: a hydrocarbon (low viscosity index) and a polyalkylene glycol (high viscosity index). The composite system exhibits non-linear viscosity-temperature behavior with a phase separation transition, allowing it to adapt to wide temperature ranges better than either component alone.
4Ease of operation
If the separation temperature is lowered to improve low-temperature pumpability, then the oil separates earlier (improving pump feed), but the kinematic viscosity at high temperatures may decrease (affecting lubrication performance)
Solution Approach 1:
The invention uses the low-viscosity hydrocarbon phase as a 'copy' or surrogate that separates out at low temperatures to provide pumpability, while the high-viscosity polyalkylene glycol phase remains as the active lubricating component. The separated hydrocarbon phase effectively copies the low-temperature fluidity needed for pumping, while the PAG phase maintains high-temperature lubrication performance.
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 two-phase system ensures effective lubrication by maintaining kinematic viscosity at high temperatures and reducing separation temperature, allowing the low-viscosity constituent to contribute at low temperatures and the high-viscosity constituent to compensate at high temperatures, thus preventing oil film breakdown and pump issues.
Implementation Method 1
A two-phase lubricating oil composition comprising a low-viscosity hydrocarbon, a high-viscosity polyalkylene glycol, and a control aliphatic ester, where the oxygen/carbon weight ratio of the ester influences the mixing behavior, allowing for controlled separation temperature
Data Source
Figure 1~2
Figure 3
AI summary
Lubricating oil composition comprising a mixture of: (A) a hydrocarbon as a low-viscosity constituent, (B) a polyalkylene glycol (PAG) as a high-viscosity constituent wherein the oxygen/carbon weight ratio is in the range of from 0.450 to 0.580, and (C) a compound as a control constituent wherein the oxygen/carbon weight ratio is in the range of from 0.080 to 0.350. The present invention offers offer a lubricating composition which has two constituents, a low-viscosity constituent together with a high-viscosity constituent which is capable of phase separation from the low- viscosity constituent at low temperatures, and which becomes uniform at high temperatures. By using a control constituent, it is possible both to control appropriately the separation temperature of the lubricating oil composition which is in the form of a mixture of two constituents, and to maintain the kinematic viscosity at high temperatures at almost the same level as when not using the control constituent. Given that the low- viscosity constituent functions at low temperatures and that at high temperatures the lubricating oil functions with a viscosity enhanced by mixing of the high-viscosity constituent and the low-viscosity constituent, it is possible to use such a lubricating oil composition over a wide range of temperatures.