Double-Jacket Electric Machine Casing for Inspectable Cooling Seals

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Solution Overview

Problem

Existing double-jacketed electrical machines lack easy visual inspection of the fluid circuit and are not designed to operate reliably in severe environmental conditions, such as those found in the nuclear field.

Innovation Solution

A double-jacketed electrical machine casing design where the inner and outer casings are removable, allowing for easy inspection of the fluid circuit, with features like radial clearance and seals to prevent fluid leakage, and ribs to enhance cooling, all made from stainless steel for durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the inner casing and outer casing are permanently fixed together by welding, then the structural strength and sealing are improved, but the ability to inspect the fluid circulation space is lost

Engineering Contradiction:

Improvesealing reliabilityVSAvoidinspection accessibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The casing is divided into separable inner and outer parts that can be disconnected for inspection. The inner casing and outer casing are designed as separate components that can be assembled and disassembled, allowing the fluid circulation space to be accessed for inspection while maintaining structural integrity during operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connection between inner and outer casings transitions from static permanent welding to dynamic removable fastening. The casings are fastened together during operation to ensure sealing, but can be separated when inspection is required, providing operational flexibility.

Inventive Principle:

Principle #15Dynamics

2Ease of manufacture

If the end plate is made integral with the inner casing, then the manufacturing complexity is reduced, but the disassembly process becomes more complex when inspection is needed

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiddisassembly complexity

Core Design Contradiction:

Ease of manufactureVSEase of repair

Solution Approach 1:

The end plate is separated from the inner casing as a distinct component. This allows the end plate to be independently removed when the outer casing needs to be detached for inspection, simplifying the disassembly process compared to an integral design where the end plate would be permanently attached.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If the outer casing is designed as a cylindrical sleeve without end walls, then the manufacturing is simplified, but the sealing of the fluid circulation space becomes more difficult

Engineering Contradiction:

Improvecasing manufacturingVSAvoidfluid circulation sealing

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The outer casing is designed with separate end walls that can be attached to the cylindrical sleeve portion. This segmentation allows the main body to be manufactured as a simple sleeve while adding end walls to provide proper sealing surfaces for the fluid circulation space.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Sealing elements are introduced as intermediary components between the inner and outer casings. These seals facilitate the connection and ensure proper sealing of the fluid circulation space while allowing the casings to remain as separate, easily manufactured components.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Shape

If radial clearance is eliminated between the end flange and outer casing, then the structural compactness is improved, but the protection against fluid leakage in case of seal failure is reduced

Engineering Contradiction:

Improvecasing compactnessVSAvoidfluid leakage protection

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

A radial clearance is intentionally maintained between the end flange and outer casing as a protective measure. This clearance acts as a safety feature that prevents fluid from leaking into the machine interior in case of seal failure, directing leakage outward instead.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

Enables reliable operation in severe conditions and facilitates easy inspection without disassembly, ensuring the machine's interior remains protected against seal failure and allowing efficient cooling through a zigzag fluid path.

Implementation Method 1

a circulation of a fluid within the double jacket

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

cooled by a circulation of a fluid within the double jacket

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

The casing comprises a seal, in particular an O-ring, between the rear end wall of the inner casing and the rear end wall of the outer casing

Methodology Applied

Scientific EffectSealing:

Data Source

PatentEP3465884B1Casing of an electric machine with a cooling jacket

Publication Date: 2025.09.17 MOTEURS LEROY SOMER

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AI summary

Disclosed is a double-casing frame of an electric machine that is cooled by a fluid circulating in the fluid circulation space (26) inside the double casing, said double-casing frame comprising: an inner casing (22) on which an end flange (30) is mounted at the rear of the machine; and an outer casing (24) that fits over the inner casing (22) and can be separated from the inner casing (22) without removing the end flange (30).