Rotary Machine Casing Sealing via Mated Protrusions

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Solution Overview

Problem

Conventional induction motors face challenges with increased parts count and reduced assembly ease due to the need for sealing members in cooling medium passages, and insufficient rigidity from mated interfitting portions, leading to potential deformation and refrigerant leakage under vibration.

Innovation Solution

An external cover-cooled rotary electric machine design featuring a center frame with mated recess and protrusion portions for radial positioning and sealing, eliminating the need for separate sealing members and enhancing rigidity by forming the refrigerant passage with cut surfaces that fit together without gaps, thus reducing the number of parts and improving assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sealing members are used to seal the opening portions of cavities in the stator frame, then the cooling medium passage can be sealed, but the number of parts increases and ease of assembly deteriorates

Engineering Contradiction:

Improvesealing of cooling medium passageVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the sealing function with the mated interfitting portions between the stator frame and end brackets. The recesses in the stator frame and protrusions in the end brackets are designed to not only provide mechanical positioning and connection but also to seal the opening portions of the cooling medium passage cavities. This integration eliminates the need for separate sealing members, reducing the number of parts while maintaining reliable sealing of the cooling medium passage.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If mated interfitting portions with shallow-based indentations and protrusions are used for radial positioning, then the positioning function is achieved, but the rigidity of the assemblage is insufficient

Engineering Contradiction:

Improveradial positioningVSAvoidrigidity of assemblage

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent enhances the mated interfitting portions by designing them with both radial and axial dimensions. The recesses in the stator frame and protrusions in the end brackets extend in the axial direction, creating deep-based interfitting structures rather than shallow ones. This dimensional extension in the axial direction significantly increases the rigidity of the assemblage while maintaining the radial positioning function, preventing deformation under vibration and load.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If the stator frame and end brackets are fitted together with insufficient rigidity, then assembly is simple, but deformation occurs under vibration causing refrigerant leakage

Engineering Contradiction:

Improveassembly simplicityVSAvoidprevention of refrigerant leakage

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent combines the sealing function with the structural connection function in the mated interfitting portions. The recesses and protrusions are designed to simultaneously provide mechanical connection for simple assembly and sealing to prevent refrigerant leakage. By making the interfitting portions deep-based and extending them in the axial direction, the design ensures sufficient rigidity to prevent deformation under vibration while maintaining assembly simplicity, thus eliminating refrigerant leakage without complicating the assembly process.

Inventive Principle:

Principle #5Merging (Combining)

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 reduces the number of parts required, simplifies assembly, increases the rigidity of the casing, and prevents refrigerant leakage by using the mated protrusions as sealing members, while maintaining efficient cooling through the refrigerant passage.

Implementation Method 1

an elastic sealing member is disposed annularly on an opposite side of whichever mated recess portion of the first mated recess portion and the second mated recess portion the refrigerant passage has the opening from the first inner wall surface so as to be held between an end surface of the center frame and an end surface of whichever bracket of the first bracket and the second bracket faces the mated recess portion

Methodology Applied

Scientific EffectSealing:

Implementation Method 2

perform cooling by making a refrigerant flow through the center frame

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

a refrigerant passage through which the refrigerant is made to flow is formed inside the center frame

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS8736119B2External cover-cooled rotary electric machine and casing used therein

Publication Date: 2014.05.27 MITSUBISHI ELECTRIC MOBILITY CORP

AI summary

A center frame is fastened to a first bracket and a second bracket such that a first mated protrusion and a second mated protrusion are fitted together with a first mated recess portion and a second mated recess portion so as to be mated. O rings are disposed annularly so as to be held between an end surface of the first bracket and a first axial end surface of the center frame, and between an end surface of the second bracket and a second axial end surface of the center frame on an opposite side from outer circumferential inner wall surfaces of the first mated recess portion and the second mated recess portion.