Closed Rotary Electric Machine Internal Air Cooling System

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Solution Overview

Problem

Existing cooling systems for closed rotating electrical machines, particularly air cooling systems, are inefficient and limited in effectively dissipating heat generated within the machine, especially for high-power applications, leading to performance degradation and reduced lifespan.

Innovation Solution

A closed rotating electrical machine with two internal fans mounted on the rotor shaft, directing airflow through fins on the flanges to capture heat, combined with external cooling means that can utilize either air or liquid to efficiently cool the carcass and stator, ensuring effective heat dissipation without significant electrical energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If air cooling is used for closed electrical machines, then the machine can be sealed (IP67 protection), but the cooling efficiency is insufficient for high-power applications

Engineering Contradiction:
Improvesealed machine capabilityVSAvoidcooling efficiency
Core Design Contradiction:
Adaptability or versatilityVSTemperature

Solution Approach 1:

The cooling system is segmented into multiple independent air circulation circuits: an external circuit with fans and ducts for overall cooling, and internal circuits with separate ducts for cooling the rotor and stator independently. This segmentation allows each circuit to be optimized for its specific cooling target, achieving effective heat dissipation in sealed high-power machines.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Cooling ducts act as intermediaries between the external air cooling system and the internal components (rotor and stator). The ducts transmit cooled air from the external circuit to the internal components, enabling heat transfer from high-power components to the external cooling environment while maintaining the sealed structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If conventional air cooling systems are used, then the structure is simple, but heat generated at the rotor cannot be effectively evacuated

Engineering Contradiction:
Improvecooling system structureVSAvoidrotor heat dissipation
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The cooling system is segmented into multiple independent air circulation circuits: an external circuit with fans and ducts for overall cooling, and internal circuits with separate ducts for cooling the rotor and stator independently. This segmentation allows each circuit to be optimized for its specific cooling target, achieving effective heat dissipation in sealed high-power machines.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling system transitions from surface-level external cooling to multi-dimensional internal cooling by introducing internal ducts that penetrate into the rotor and stator. This dimensional extension allows direct heat extraction from internal components, not just from external surfaces.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Temperature

If liquid cooling systems are used for high-power machines, then cooling efficiency improves, but the machine structure becomes more complex and energy consumption increases

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcooling system structure
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The system uses pneumatic cooling (air circulation) instead of hydraulic cooling (liquid circulation). By using fans to circulate air through external and internal ducts, the system achieves effective cooling of high-power machines without the structural complexity and energy consumption associated with liquid cooling systems, including pumps, seals, and coolant management.

Inventive Principle:
Principle #29Pneumatics and hydraulics

4Adaptability or versatility

If air cooling is used for closed machines, then sealing is possible, but mechanical losses increase due to fan operation

Engineering Contradiction:
Improvesealed machine capabilityVSAvoidmechanical losses
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The cooling system uses dynamic air circulation with fans that can adjust their operation based on thermal load. The external fans and internal fans operate at variable speeds to match the cooling requirements, reducing mechanical losses when full cooling capacity is not needed while maintaining effective cooling when required.

Inventive Principle:
Principle #15Dynamics

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 proposed cooling system effectively cools the rotor, shaft, coil heads, and casing of high-power electrical machines, maintaining performance and extending lifespan while minimizing mechanical losses and electrical energy consumption.

Implementation Method 1

a cooling system comprising a pair of internal fans arranged inside the casing to create an air flow inside the casing during the rotation of the rotor

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 2

the internal face of the flanges comprising fins arranged on a peripheral part of the housing of the bearing to direct the flow of air and capture the heat of said flow of air

Methodology Applied
Scientific EffectHeat Conduction: Conduction (thermal)

Implementation Method 3

capture the heat of said flow of air

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

external cooling means for cooling the carcass and the front and rear flanges

Methodology Applied
Scientific EffectHeat Exchange: Heat Exchanger

Data Source

PatentEP3526887B1Closed rotary electric machine comprising an internal air cooling system
Publication Date: 2021.07.28 MAVEL EDT SPA
  • EP3526887B1 patent drawingFigure 1A~2B
  • EP3526887B1 patent drawingFigure 3A~4B
  • EP3526887B1 patent drawingFigure 5~6

AI summary

The invention relates to a closed rotary electric machine incorporating a cooling system which comprises two internal fans (181, 182) securely mounted on the shaft (160) of the rotor (150), at the two ends of the rotor (150), each facing the internal face (111, 121) of a flange (110, 120) comprising fins (113, 123) capable of directing the airflow created by the internal fans and capable of capturing its heat. The casing, which contains the rotor and the stator (190) of the electric machine, is closed in a sealed manner by two flanges. The cooling system also comprises external cooling means for cooling the casing and flanges, which cooling can be by air (fan 140) or by liquid.