Compressor Motor Insulation for Hydrolysis-Resistant Heat Pumps
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Solution Overview
Problem
Current heat pump systems face issues with the hydrolysis of insulating materials due to high hygroscopicity of refrigerating machine oil and increased temperatures, poor chemical stability of low-GWP refrigerants like hydro-olefin-based fluorohydrocarbons, and challenges in suppressing decomposition and polymerization reactions in the compressor slidable sections.
Innovation Solution
A heat pump apparatus utilizing a wholly aromatic liquid crystal polyester (LCP) as the insulating material and a refrigerant mixture of difluoromethane (HFC-32) with ethylene-based fluorohydrocarbons, where the refrigerating machine oil has a low water absorption rate and contains a flame retardant to suppress decomposition reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulating materials (PET, PEN, PPS) are used in the electric motor, then the motor can operate, but the insulating material undergoes hydrolysis due to high hygroscopicity of refrigerating machine oil and increased temperatures, leading to deterioration
Solution Approach 1:
The patent changes the chemical composition parameters of the insulating material from conventional PET/PEN/PPS to a fluorinated polymer with specific molecular structure containing CF2 groups, which fundamentally alters the material's resistance to hydrolysis and chemical stability under high temperature and humid conditions
Solution Approach 2:
The patent uses a composite approach by combining fluorinated polymer material with specific molecular structure to create an insulating material that simultaneously provides electrical insulation, hydrolysis resistance, and thermal stability, overcoming the limitations of single-material solutions
2Object-affected harmful factors
If low-GWP refrigerants like hydro-olefin-based fluorohydrocarbons are used, then environmental impact is reduced, but the refrigerant exhibits poor chemical stability and undergoes decomposition and polymerization reactions in the compressor slidable sections
Solution Approach 1:
The patent introduces a flame retardant as an intermediary substance that mediates between the low-GWP refrigerant and the high-temperature environment in the compressor, suppressing decomposition reactions and preventing polymerization while allowing the refrigerant to maintain its low environmental impact
Solution Approach 2:
The patent changes the chemical composition of the refrigerant by selecting specific hydro-olefin-based fluorohydrocarbons with controlled molecular structures and combining them in specific ratios, thereby improving chemical stability while maintaining low GWP properties
3Strength
If refrigerating machine oil with high hygroscopicity is used to lubricate the compression mechanism, then lubrication is effective, but the oil absorbs water and promotes hydrolysis of insulating materials
Solution Approach 1:
The patent changes the chemical composition parameters of the refrigerating machine oil by selecting specific base oils and additive packages that provide effective lubrication while having low hygroscopicity, thereby reducing water absorption and preventing hydrolysis of insulating materials
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 solution provides long-term reliability and stability to the heat pump system by preventing hydrolysis of insulating materials and suppressing refrigerant decomposition, maintaining efficiency and reducing the risk of damage from explosive decomposition reactions.
Implementation Method 1
the insulating material is a wholly aromatic liquid crystal polyester (LCP) having a molecular main chain constituted by a monomer including p-hydroxybenzoic acid (PHB) as an essential monomer and a monomer solely including benzene-ring as another monomer via an ester bond
Implementation Method 2
The refrigerating machine oil has a saturated water content of 2% or less at 40 degrees C and a relative humidity of 80%, for 24 Hr
Implementation Method 3
a refrigerant mixture of difluoromethane (HFC-32) with ethylene-based fluorohydrocarbons, where the refrigerating machine oil has a low water absorption rate and contains a flame retardant to suppress decomposition reactions
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An insulating material that tends not to hydrolyze is used to thereby provide a heat pump apparatus having long-term reliability. An electric motor (6) of a compressor (1) is fixed to a sealed container (10) and includes a stator (6s) around which a winding wire (6w) is wound through intermediation of an insulating material (7), and a rotor (6r) surrounded by the stator (6s). The insulating material (7) is a wholly aromatic liquid crystal polyester (LCP) having a molecular main chain constituted by a monomer including p-hydroxybenzoic acid (PHB) as an essential monomer and a monomer solely including benzene-ring as another monomer via an ester bond. The refrigerating machine oil has a saturated water content of 2% or less at 40 degrees C, a relative humidity of 80%, for 24 Hr. To suppress the explosive decomposition reaction of ethylene-based fluorohydrocarbon, a flame retardant is used to generate chemical species that complement active radicals that cause the decomposition reaction.