PAG Lubricant Composition for Motor-Integrated Compressors
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Solution Overview
Problem
There is a need for lubricants suitable for use with HFO-1234yf refrigerants, particularly in motor-integrated compression-type refrigeration/air conditioning systems, that exhibit appropriate miscibility, chemical, thermal, and hydrolytic stability, as well as specific electrical properties to prevent leakage currents in electrically driven compressors.
Innovation Solution
A polyalkylene glycol (PAG) lubricant basefluid with a specific formula, RX(R b< O) y R c<, is developed, which is purified to have a Total Acid Value of less than 0.03 mgKOH/g, a cation content of less than 30 ppm, and a moisture content of less than 300 ppm, resulting in a lubricant with a minimum volume resistivity of 1 x 10^12 ohm cm, ensuring no electrical leakage current in motor-integrated compressors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PAG lubricant is used with HFO-1234yf refrigerant in motor-integrated compressors, then lubrication performance is improved, but electrical leakage current increases
Solution Approach 1:
The patent changes the chemical composition parameters of the PAG lubricant by specifying precise molecular weight distributions (average molecular weights of 350-750 g/mol) and structural characteristics to achieve optimal balance between lubrication performance and electrical resistivity, thereby reducing electrical leakage current while maintaining reliable lubrication
2Stability of the object's composition
If conventional PAG lubricant is used, then miscibility with refrigerant is achieved, but chemical stability deteriorates
Solution Approach 1:
The patent optimizes the chemical structure parameters of PAG lubricant by controlling the ratio of different polyether units and specifying molecular weight ranges to simultaneously achieve high chemical stability (resistance to decomposition) and adequate miscibility with HFO-1234yf refrigerant across operating temperature ranges
3Object-affected harmful factors
If purified PAG lubricant is used, then electrical resistivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary purification actions during the lubricant manufacturing process, including filtration and drying steps performed before final assembly, to remove impurities that would affect electrical resistivity, thereby achieving high electrical performance without requiring complex post-manufacturing treatment
Data Source
AI summary
A PAG lubricant basefluid for use with a fluoroalkene refrigerant, the basefluid containing a PAG having the formula: RX(RaO)x(RbO)yRc, where R is selected from alkyl groups having from 1-10 carbon atoms, acyl groups having from 1-10 carbon atoms, aliphatic hydrocarbon groups having from 2-6 valencies, and substituents containing a heterocyclic ring in which the heteroatom(s) are oxygen; X is O or S; Ra is a C2 alkylene group; Rb is a C3 alkylene group; Rc is the same as R or is an H; x and y are each independently 0 or an integer ? 100; and the sum of x + y is an integer in the range of from about 5-100. Refrigeration and lubricant compositions containing the PAG lubricant basefluid and a method of operating a motor-integrated compressor of a refrigeration or air conditioning system with substantially no electrical leakage current are also provided.