Sealed Motor Heat Exchanger for Thermal Runaway

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Solution Overview

Problem

Existing closed electric motors used in rail transport vehicles face thermal runaway due to insufficient heat dissipation, particularly in operating regimes where heat generated by the conversion of electrical energy into mechanical energy is not effectively transferred to the liquid cooling system, leading to complex and non-modular thermal coupling solutions that are difficult to install and require special arrangements.

Innovation Solution

A closed electric motor design featuring a heat exchanger with a simple, reliable thermal coupling mechanism that includes a heat exchanger made from a good heat-conducting material, such as aluminum, integrated with the motor's casing and liquid cooling system, allowing for efficient heat transfer through a gaseous volume and easy installation without requiring specific motor arrangements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a thermal coupling device is installed to improve heat transfer from the engine interior compartment to the liquid cooling system, then heat dissipation efficiency is improved, but device complexity increases and installation becomes difficult

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoiddevice complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The heat exchanger is nested within the interior compartment of the motor, utilizing the available space efficiently. The heat exchanger core is positioned inside the compartment while its cooling fins extend outward, nesting multiple functional elements within the motor structure without increasing overall footprint.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The heat exchanger acts as an intermediary component between the motor's interior compartment and the liquid cooling system. It mediates heat transfer from the hot interior compartment air to the cooling liquid flowing through its channels, enabling efficient thermal coupling without direct contact between the cooling system and motor components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If a thermal coupling device is installed to improve heat transfer, then heat dissipation efficiency is improved, but ease of installation deteriorates as it cannot be added during motor life

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoidease of installation
Core Design Contradiction:
TemperatureVSEase of operation

Solution Approach 1:

The heat exchanger is designed as a separate, modular component that can be independently installed. The heat exchanger core and fin assembly are segmented from the motor housing, allowing it to be added as a distinct unit during maintenance or upgrades without requiring motor disassembly or special arrangements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The heat exchanger is pre-assembled with its cooling fins and core structure before installation into the motor. This preliminary preparation allows for quick installation during motor maintenance without requiring complex on-site assembly procedures or special motor configurations.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If conventional heat dissipation through casing conduction is used, then device simplicity is maintained, but heat dissipation efficiency becomes insufficient leading to thermal runaway

Engineering Contradiction:
Improvedevice simplicityVSAvoidheat dissipation efficiency
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The heat exchanger utilizes liquid cooling hydraulics to improve heat dissipation. Cooling liquid flows through channels in the heat exchanger core, carrying heat away from the motor interior compartment much more efficiently than air conduction through the casing, preventing thermal runaway while maintaining relative simplicity.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The heat exchanger changes the thermal parameters of the cooling system by introducing a liquid cooling medium with high heat capacity and thermal conductivity. This parameter change enables significantly higher heat transfer rates compared to the original air conduction system, solving the insufficient heat dissipation problem.

Inventive Principle:
Principle #35Parameter changes

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 reduces the interior compartment temperature by approximately 10°C, providing a simpler and more reliable thermal management system that can be easily integrated during the motor's life cycle, addressing the inefficiencies of previous solutions.

Implementation Method 1

heat transfer from the engine interior compartment to the liquid cooling system

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

heat transfer through a gaseous volume

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

liquid cooling means for liquid cooling of the interior compartment of the motor

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 4

means for converting the electrical energy received by the motor into mechanical energy

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 5

heat generated by the operation of the engine... by Joule effect

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2634896B1Sealed electric motor comprising a heat exchanger
Publication Date: 2021.07.28 ALSTOM TRANSPORT TECH SAS
  • EP2634896B1 patent drawingFigure 1
  • EP2634896B1 patent drawingFigure 2

AI summary

This engine comprises a frame (12) delimiting an internal compartment (14) defining an internal gaseous volume (15), means (16) for converting the electrical energy received by the engine (10) into mechanical energy, including a stator (64) and a rotor (62), the stator (64) comprising at least some coils (86), means (18) for liquid cooling of the internal compartment (14), and means (20) for thermal coupling between the internal compartment (14) and the liquid cooling means (18). The thermal coupling means (20) include a heat exchanger (108) mounted on the frame (12) in the internal compartment (22), having a support (116) applied to the frame (12) and at least one radial projection (118) extending towards the central axis A-A'.