Electric Motor Bypass Flow Passage for Earth Conductor Protection
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Solution Overview
Problem
High-pressure refrigerant vaporization during cooling in electrical motors can cause fiber-like conductors used as earth conductors to degrade and leak, leading to electrical corrosion and contamination of lubrication oil.
Innovation Solution
A bypass flow passage is implemented within the motor case, allowing refrigerant gas to escape through a lower resistance path instead of through the gap between the earth conductor and rotor shaft, thereby protecting the fiber-like conductors and maintaining efficient electrical charge elimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling device sprays refrigerant liquid to cool the motor inside, then cooling effect is improved, but refrigerant gas leaks through the gap between earth conductor and rotor shaft causing degradation of fiber-like conductors
Solution Approach 1:
A bypass flow passage is introduced as an intermediary path for refrigerant gas to flow through. This passage is formed between the motor case and the earth conductor, providing a dedicated channel that separates the refrigerant flow from the fiber-like conductors. The bypass passage allows high-velocity refrigerant gas to escape without directly contacting and degrading the earth conductor materials.
Solution Approach 2:
The flow path is segmented into two separate channels: one for refrigerant gas flow (bypass passage) and another for electrical charge elimination (gap between earth conductor and rotor shaft). This segmentation allows the cooling function and the earthing function to operate independently without interfering with each other, preventing the refrigerant gas from damaging the fiber-like conductors while maintaining both cooling effectiveness and electrical protection.
2Reliability
If fiber-like conductors are used as earth conductor, then electrical charge elimination is achieved, but conductors are damaged by high-velocity refrigerant gas flow
Solution Approach 1:
The bypass flow passage acts as a mediator that intercepts the refrigerant gas flow before it can reach the fiber-like conductors. By providing this intermediate flow path, the harmful high-velocity gas is directed away from the earth conductor, allowing the conductors to maintain their electrical charge elimination function without suffering mechanical degradation from gas flow.
3Productivity
If refrigerant gas flows through the gap between earth conductor and rotor shaft, then cooling efficiency is improved, but fiber-like conductors are fluttered and degraded
Solution Approach 1:
The bypass flow passage serves as an intermediary structure that captures and directs the refrigerant gas flow. Instead of allowing the gas to flow directly through the gap between the earth conductor and rotor shaft (which would cause conductor degradation), the bypass passage provides a separate route that maintains cooling efficiency while protecting the conductors from harmful gas flow impacts.
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 solution prevents damage to the earth conductors and ensures stable electrical charge elimination by directing refrigerant gas flow through a larger cross-sectional area bypass passage, reducing the risk of corrosion and contamination.
Implementation Method 1
it sprays refrigerant liquid to an inside of a motor for cooling by vaporization heat
Implementation Method 2
distal ends of the fiber-like conductors are contacted with the rotor shaft. According to this configuration, the electrical charge remained in the rotor shaft flows to the motor case through the fiber-like conductors
Data Source
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AI summary
An electrical motor includes a motor case inside which an inner space is formed, a bearing disposed so as to pass through a wall of the motor case, a rotor shaft rotatably supported by the bearing, and an earth conductor that is fixed with the motor case and includes a frame and an electrical conductor provided on the frame. The frame has an annular or curved inner circumferential surface along an outer circumference of the rotor shaft and is fixed with the motor shaft. The electrical conductor is disposed on the inner circumferential surface of the frame so that an end of the electrical conductor is slidably contacted with the rotor shaft. A bypass flow passage is provided between the earth conductor and the motor case. The inner space and an outside of the motor case are communicated with each other via the bypass flow passage. According to the electrical motor, its inside can be cooled without damaging the earth conductor.