Hermetic Compressor Motor Coils Segmentation for Insulation Breakdown
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Solution Overview
Problem
Hermetically sealed compressors face challenges with heat generation and insulation breakdown at the connection between lead wires and external terminals due to the use of aluminum wires with larger diameters, which increases coil resistance and reduces insulation distance, leading to potential shorts and local Joule loss.
Innovation Solution
The compressor design features multiple turns of individual coils to reduce wire radius, allowing for proper crimping and insulation, with distributed external terminals and crimped terminal blocks to maintain pressure resistance and standardization, using aluminum wires covered with fluorine resin for corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum wires with larger diameters are used for coils to reduce coil resistance, then electrical conductivity is improved, but the distance between crimped areas of external terminals becomes shorter, increasing the risk of insulation breakdown
Solution Approach 1:
The patent divides each coil into multiple individual coils (e.g., three individual coils per stator phase), allowing each to be connected to separate external terminals. This segmentation reduces the current load per terminal and increases the distance between crimped areas, preventing insulation breakdown while maintaining electrical conductivity.
Solution Approach 2:
The patent transitions from a single-coil configuration to a multi-coil configuration, adding dimensional complexity to the terminal arrangement. This allows external terminals to be distributed more widely across the terminal block, increasing spacing and reducing the risk of insulation breakdown between adjacent crimped areas.
2Reliability
If the diameter of aluminum wires is increased to reduce coil resistance, then electrical conductivity is improved, but it becomes difficult to ensure strong compressive force extends to the center of the wire bundle during crimping, leading to gaps and insufficient conductive contact
Solution Approach 1:
By dividing the coil into multiple individual coils, each with smaller wire diameter, the patent enables effective crimping of each individual wire or small bundle. This ensures that compressive force from the crimp terminal extends to the center of each wire bundle, eliminating gaps and ensuring sufficient conductive contact, while still achieving the required overall electrical conductivity through parallel connections.
Solution Approach 2:
The patent changes the parameter of wire diameter from large to small by using multiple individual coils instead of a single thick wire. This parameter change makes the crimping process feasible and reliable, ensuring proper compressive force distribution and conductive contact, while maintaining the electrical conductivity requirement through the parallel configuration of multiple coils.
3Reliability
If the dimensions of external terminals are increased to improve crimping quality, then manufacturing reliability is improved, but the terminal block size increases, compromising the motor casing's ability to withstand pressure
Solution Approach 1:
The patent segments the coil connections into multiple individual coil connections, each using smaller external terminals. This allows the use of compact terminal blocks that maintain adequate spacing between crimped areas, preserving the motor casing's pressure resistance while ensuring proper crimping quality through appropriate terminal dimensions for each individual connection.
4Reliability
If aluminum wires are used for coils to resist corrosion from corrosive gases, then corrosion resistance is improved, but the larger wire diameter reduces insulation distance and increases the risk of shorts
Solution Approach 1:
The patent divides the coil system into multiple individual coils, each connected to separate external terminals. This segmentation increases the spatial distribution of connection points, maintaining adequate insulation distances between adjacent terminals even when using aluminum wires with larger diameters, thereby reducing the risk of short circuits while preserving corrosion resistance.
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
This configuration reduces localized resistance loss, prevents insulation breakdown, and maintains pressure resistance while allowing for cost-effective standardization of components, ensuring reliable operation in corrosive environments.
Implementation Method 1
a technique in which aluminum wires covered with a fluorine resin are used for the coils of a screw compressor motor in a refrigeration device that employs ammonia as a coolant
Implementation Method 2
external terminals have crimped terminal structures in which the leading ends of the coils are inserted and crimped
Implementation Method 3
the stators of the motor are each formed by winding a plurality of individual coils in multiple turns
Implementation Method 4
a hermetically sealed structure is often used, in which a compressor main body and the motor are integrally connected
Data Source
Figure 1
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Figure 3~5
AI summary
A hermetically sealed compressor in which heat generation and insulation breakdown are hardly to occur at the connection portion between a lead wire of a motor and an external terminal is configured as follows. The compressor main body and the motor are integrally structured. The flow path of a fluid to be compressed is communicated with the internal space of the motor. The stator (10) of the motor is formed by winding each of a plurality of independent coils (A1, A2, B1, B2, C1, C2) in multiple turns. Each of the coils (A1, A2, B1, B2, C1, C2) is provided with a separate external terminal (18).