Hermetic Terminal Insulation to Prevent Refrigerant Dewing
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Solution Overview
Problem
Conventional hermetic terminals for vehicular compressors do not effectively prevent dew drops from forming on the outer surface due to direct contact with refrigerant, which compromises electrical insulation.
Innovation Solution
A hermetic terminal with a heat insulating member made of materials like HNBR or EPDM, covering the metal base and lead inside the pressure-resistant container, prevents direct contact with refrigerant and thus dew formation, while maintaining refrigerant and oil resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the hermetic terminal is directly exposed to refrigerant for cooling, then heat dissipation is improved, but dew drops form on the outer surface compromising electrical insulation
Solution Approach 1:
The hermetic terminal is divided into two functional zones: an inner exposed portion that contacts refrigerant for heat dissipation, and an outer covered portion that is protected from refrigerant contact to prevent dew formation. The terminal includes a base portion and a lead portion, with the heat insulating member selectively covering specific surfaces to maintain electrical insulation while allowing heat transfer from internal components.
Solution Approach 2:
A heat insulating member made of refrigerant-resistant material (such as fluororesin or silicone rubber) is introduced as an intermediary between the hermetic terminal and the refrigerant. This intermediary layer prevents direct contact between the refrigerant and the terminal's outer surface, thereby preventing dew drop formation while still allowing the terminal to function electrically and thermally through the insulating barrier.
2Reliability
If insulating coat such as silicone rubber is applied on metal base and lead for electrical insulation, then electrical insulation is improved, but refrigerant and oil resistance is compromised
Solution Approach 1:
The material properties of the heat insulating member are specifically selected to achieve a balance between electrical insulation, refrigerant resistance, and oil resistance. Materials such as fluororesin (e.g., PTFE, FEP) or silicone rubber are chosen because they maintain high electrical insulation properties while simultaneously exhibiting excellent resistance to refrigerants and lubricating oils, thus resolving the contradiction through material parameter optimization.
Solution Approach 2:
The heat insulating member is constructed from composite or specially formulated materials that combine multiple desirable properties: electrical insulation capability, refrigerant resistance, and oil resistance. These composite materials integrate the benefits of different material characteristics to simultaneously satisfy all three requirements that individual materials cannot meet alone.
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
Prevents dew drops from forming on the outer surface of the hermetic terminal, enhancing electrical insulation and resistance to refrigerant and lubricating oil.
Implementation Method 1
a heat insulating member 14 that is provided to cover at least a partial surface of the hermetic terminal 10 which is located inside a pressure-resistant container 35 after the hermetic terminal 10 is fixed to the pressure-resistant container 35 and comes into contact with refrigerant sealed in the pressure-resistant container 35
Data Source
AI summary
The hermetic terminal includes a metal base that is provided with at least one sealing hole, a lead that is inserted in the sealing hole provided on the metal base, an insulating material that hermetically seals the metal base and the lead, and a heat insulating member that is provided to cover at least a partial surface of the hermetic terminal which is located inside a pressure-resistant container after the hermetic terminal is fixed to the pressure-resistant container and comes into contact with refrigerant sealed in the pressure-resistant container.