Electrical Equipment Thermal Tolerance via Segmented Casing

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Solution Overview

Problem

Rotating electrical equipment, such as electric motors, face issues with stator detachment due to thermal expansion differences between ferrous stator materials and aluminum alloy casing, leading to operational instability and safety risks.

Innovation Solution

The equipment incorporates a plurality of fixing bars and slots in the casing, allowing for better thermal expansion adaptation and simplified assembly, with a flexible seal and reduced rigidity to maintain stator centering and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of stationary object

If the circumferential wall is made of aluminum alloy to reduce mass and improve heat dissipation, then the mass and thermal conductivity are improved, but the stator attachment is lost due to thermal expansion differences

Engineering Contradiction:

Improvemass of equipmentVSAvoidstator attachment

Core Design Contradiction:

Weight of stationary objectVSReliability

Solution Approach 1:

The circumferential wall is segmented by introducing axial slots that divide the continuous structure into sections. This segmentation reduces the overall rigidity of the wall, allowing it to accommodate thermal expansion differences between the aluminum alloy casing and ferrous stator without compromising stator attachment. The slots create flexible zones that can deform independently to absorb dimensional changes during thermal cycles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rigidity parameter of the circumferential wall is changed by introducing slots that reduce structural stiffness. This parameter modification allows the wall to transition from a rigid structure that would crack or detach under thermal stress to a semi-flexible structure that can adapt to thermal expansion while maintaining stator attachment through controlled deformation.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If the circumferential wall is made of aluminum alloy to improve heat dissipation, then the thermal conductivity is improved, but the rigidity is reduced making assembly more difficult

Engineering Contradiction:

Improveheat dissipationVSAvoidassembly difficulty

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The circumferential wall is divided into segments by axial slots, creating a modular structure that is easier to assemble. The segmented design allows components to be fitted together more readily and accommodates manufacturing tolerances, simplifying the assembly process while maintaining the thermal conductivity benefits of aluminum alloy.

Inventive Principle:

Principle #1Segmentation

3Force

If radial clamping is applied by the side walls to hold the stator, then the stator is fixed in position, but the stator rotation and off-centering occur due to thermal expansion

Engineering Contradiction:

Improveradial clamping forceVSAvoidstator centering

Core Design Contradiction:

ForceVSStability of the object's composition

Solution Approach 1:

The circumferential wall transitions from a static rigid structure to a dynamic semi-flexible structure capable of controlled deformation. During thermal expansion, the wall with slots can deform radially and axially to maintain optimal contact pressure with the stator, ensuring continuous radial clamping force while accommodating dimensional changes that would otherwise cause stator rotation or off-centering.

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

This design ensures the stator's secure fixation and centering during operation, enhancing heat dissipation and reducing the risk of accidents by accommodating thermal expansion differences between materials.

Implementation Method 1

the aluminum alloy walls tend to expand more than the ferrous material stator when the internal temperature of the equipment rises during its operation

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the equipment comprising a plurality of bars extending in the ducts and having ends fixed to the flanges

Methodology Applied

Scientific EffectMechanical fastening: Mechanical Fastener

Implementation Method 3

The reduced rigidity of the walls, obtained by the softer material and the slot, further facilitates the assembly of the equipment

Methodology Applied

Scientific EffectThermal expansion accommodation: Thermal Expansion

Data Source

PatentEP4213345A1Electrical equipment with improved thermal tolerance, and associated vehicle

Publication Date: 2023.07.19 ALSTOM HOLDINGS SA

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AI summary

An electrical device (20) comprises: - a protective housing (30) including a circumferential lateral wall (46) made of a first material and two end flanges (48), the housing (30) defining an internal space (32) around a central axis (A), and - a stator (34) made of at least one second material, disposed in the internal space (32) around the axis (A). The stator (34) includes a plurality of mounting conduits (58) extending parallel to the axis (A) and opening on either side of the stator (34). The device (20) includes a plurality of bars (44) extending within the conduits (58) and having ends (64) fixed to the flanges (48). The circumferential wall (46) has at least one slot (51) passing through a whole thickness of the circumferential wall (46) and extending from one flange (48) to the other.