Encapsulated Rotor Cooling Structure for Brushless Electric Motors
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Solution Overview
Problem
Brushless electric motors with encapsulated rotors face challenges in maintaining acceptable temperatures due to overheating, which can damage permanent magnets, and existing cooling solutions are either complex or inadequately encapsulated, making them susceptible to contamination and reducing their lifespan.
Innovation Solution
A heat dissipating element with high thermal conductivity, such as aluminum, is attached to the rotor packet, forming a gap seal with the stator coil body to prevent contamination and efficiently conduct heat away, while a fan wheel with high thermal conductivity enhances heat dissipation, maintaining the rotor at a safe temperature without additional cost or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor is encapsulated to protect it from contamination, then the rotor is protected from metal dust and contaminants, but the rotor overheats due to trapped heat
Solution Approach 1:
The encapsulation is segmented into multiple parts: the motor housing forms the outer enclosure, while the stator assembly with its mounting flange creates an inner sealing structure. This segmentation allows the gap between the heat dissipating element and stator to form a seal that blocks contaminants while the segmented structure itself provides thermal management pathways.
Solution Approach 2:
The heat dissipating element acts as an intermediary component between the rotor and the external environment. It provides a dual function: thermally coupling with the rotor to conduct heat away, while its positioning relative to the stator creates a gap seal that prevents contaminant ingress. This intermediary structure resolves the contradiction by mediating between thermal management and contamination protection requirements.
2Temperature
If cooling solutions are added to the encapsulated motor, then rotor overheating is prevented, but the device complexity increases
Solution Approach 1:
The heat dissipating element is merged with the rotor assembly, forming an integrated thermal management component. The fan wheel is coupled to this heat dissipating element, combining the cooling function with the existing rotor structure. This merging eliminates the need for separate, complex cooling systems while effectively managing rotor temperature.
Solution Approach 2:
The heat dissipating element serves multiple functions simultaneously: it acts as a thermal conductor to transfer heat from the rotor, provides structural support as part of the rotor assembly, and its positioning creates the gap seal for contamination protection. The fan wheel similarly provides both cooling airflow and acts as a rotor component. This multi-functionality reduces overall device complexity while achieving effective cooling.
3Power
If the output of the electric motor is increased, then the motor power is improved, but the rotor temperature increases and permanent magnets are damaged
Solution Approach 1:
The heat dissipating element provides continuous thermal coupling with the rotor, maintaining constant heat transfer from the rotor to the heat dissipating element. The fan wheel continuously moves air across the heat dissipating element surfaces, ensuring uninterrupted cooling. This continuous thermal management allows the motor to sustain higher power outputs without rotor overheating that would damage permanent magnets.
Solution Approach 2:
The system changes thermal parameters by introducing the heat dissipating element with high thermal conductivity material, fundamentally altering the thermal landscape of the motor. This parameter change enables the motor to operate at higher power levels by actively managing the temperature parameter, preventing the direct correlation between increased power output and increased rotor temperature that would otherwise damage permanent magnets.
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 effectively prevents rotor overheating, maintains the rotor's encapsulation integrity, and allows for high-output operation in electric tools like angle grinders by ensuring reliable heat dissipation and air flow, thereby extending the motor's lifespan and preventing damage to permanent magnets.
Implementation Method 1
A heat dissipating element (14) is attached to a rotor packet (8) of the rotor (4)... the heat dissipating element consists of a material with high thermal conductivity... the heat dissipating element consists of aluminum
Implementation Method 2
the heat dissipating element is connected to a fan wheel or formed in one piece with a fan wheel... Coupling the fan wheel with the heat dissipating element results in a substantial increase in the surface area of the heat dissipating element, so that a correspondingly larger amount of heat can be conveyed away from the rotor
Data Source
AI summary
The present disclosure relates to an electric motor having a stator and a rotor. The rotor is fitted with permanent magnets which are surrounded by a rotor packet. A heat dissipating element is attached to the rotor packet. A gap seal is formed between an outer diameter of the heat dissipating element and an inner diameter of a component connected to the stator. In some examples, the component may be a coil body connected to the stator.