Hydraulic Base Oil Low-Temperature Filterability
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Solution Overview
Problem
Hydraulic equipment with precision valves and small micropore filters face issues with poor lubrication and malfunction due to blockages, leading to decreased flow in hydraulic pumps at low temperatures, especially in systems with filters having micropore diameters of 50µm or less.
Innovation Solution
A specific base oil with defined kinematic viscosity, pour-point, viscosity index, and carbon composition is used to improve low-temperature filterability, combined with a poly(meth)acrylate series additive, to enhance the hydraulic oil composition's performance in such systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional lubricating oils with sufficient low-temperature viscosity (BF viscosity at -40°C ≤ 20,000mPa·s) are used, then cold flow properties are improved, but flow in hydraulic pump decreases at low temperature (particularly -30°C or less) due to blockage of micropore filters with diameter of 50μm or less
Solution Approach 1:
The invention changes the chemical composition parameters of the base oil by specifying precise ranges for n-paraffin (0-10 mass%), iso-paraffin (85-95 mass%), and naphthene (0-10 mass%), along with controlled kinematic viscosity at 40°C (2.0-6.0 mm²/s) and at 100°C (1.5-6.0 mm²/s). This compositional parameter optimization enables the oil to maintain both low-temperature flow properties and compatibility with fine filters, resolving the contradiction between cold flow performance and hydraulic pump flow at low temperatures.
2Measurement precision
If filters with smaller micropore diameter (50μm or less) are used for accurate control and contamination prevention, then measurement precision and system reliability are improved, but blockage occurs at low temperature leading to poor lubrication and malfunction
Solution Approach 1:
The invention optimizes the base oil parameters including specific viscosity ranges at different temperatures and controlled paraffin content to ensure the oil flows smoothly through filters with micropore diameter of 50μm or less at low temperatures without causing blockages, thereby maintaining both filter precision and system reliability.
3Productivity
If base oil with lower kinematic viscosity is used to improve filterability, then low-temperature filterability is improved, but lubrication ability may deteriorate
Solution Approach 1:
The invention carefully balances the kinematic viscosity parameters, specifying 2.0-6.0 mm²/s at 40°C and 1.5-6.0 mm²/s at 100°C, along with controlled composition ranges. This optimized parameter set ensures the oil maintains adequate viscosity for effective lubrication while achieving sufficient flowability through filters at low temperatures, thus resolving the contradiction between filterability and lubrication ability.
Data Source
AI summary
The object of the present invention is to provide a base oil for hydraulic oil suitably used for hydraulic systems having filters of which micropore diameter is 50µm or less, which is capable to improve the decrease of flow in a hydraulic pump at low temperature like -30°C or less and capable to normally operate the hydraulic systems. The invention also provides a hydraulic oil composition using the above base oil, especially a hydraulic oil composition suitably used for such as tractors, transmissions, and common systems thereof having the hydraulic systems. In order to achieve the object, provided is a base oil for hydraulic oil comprising mineral oil, wherein the mineral oil is defined by kinematic viscosity at 100°C: 1.5~6mm2/s, pour-point: -10°C or less, viscosity index: 100 or more, %CP: 70 or more, %CA: 2 or less, and aniline point: 106°C or more; and wherein, the mineral base oil is treated by catalytic dewaxing process and/or contains tertiary carbon atoms at a ratio of 7.4% or more to the total carbon atoms.