Stator Assembly Radial Locking Mechanism for Thermal-Free Mounting

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Solution Overview

Problem

Current stator assembly methods, such as shrink fitting, require precise heating and cooling to prevent parts from getting stuck, leading to potential assembly failures and lack of positional adjustment.

Innovation Solution

A stator assembly design featuring recessed shapes on the housing and protruding rollers on the stator, allowing for accurate positioning and locking without heating, using the rollers to exert a radial force for secure fastening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If shrink fitting is used to fasten the stator to the housing, then the assembly size is reduced and manufacturing is facilitated, but the positioning precision deteriorates due to thermal expansion and cooling variability

Engineering Contradiction:
Improveassembly processVSAvoidpositioning precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the thermal field (heating/cooling) with a mechanical field. Instead of using thermal expansion and contraction to assemble the stator to the housing, the invention uses a mechanical locking mechanism comprising a locking element that can be inserted into a locking hole to secure the stator in its final position. This mechanical substitution eliminates the need for precise thermal control while achieving accurate positioning.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a locking element as an intermediary component between the stator and the housing. This locking element fits into a locking hole and provides a reliable mechanical connection that maintains positioning precision without requiring thermal processing. The intermediary element absorbs the complexity of the connection, allowing simple and accurate assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If thermal expansion is used for shrink fitting, then the stator can be inserted freely into the housing, but the assembly reliability deteriorates due to risk of parts getting stuck at wrong position

Engineering Contradiction:
Improveinsertion processVSAvoidassembly reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies preliminary action by providing a shouldered shaft that automatically positions the locking element at the correct location before final assembly. The shouldered portion of the shaft engages with the locking element in advance, ensuring that when the locking element is inserted into the locking hole, it is already at the correct position. This prevents the reliability issue of parts getting stuck at wrong positions during thermal assembly.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces the unreliable thermal field with a reliable mechanical field. Instead of relying on thermal expansion and contraction which can cause parts to get stuck at incorrect positions, the invention uses a mechanical locking mechanism where the locking element is guided by the shouldered shaft to engage precisely with the locking hole, ensuring high assembly reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If shoulder is used to fix the final position of the assembly, then the position is fixed, but the adaptability deteriorates as no adjustment is possible

Engineering Contradiction:
Improveposition fixationVSAvoidpositional adjustment
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the locking mechanism adjustable rather than fixed. The locking element can be removed from the locking hole and repositioned to different locations, allowing the final position of the stator to be adjusted. This dynamic characteristic enables both precise positioning and adaptability, as the locking element can be relocated to accommodate different positioning requirements without requiring new components.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3073613B1Stator assembly and magnetic bearing or electric motor comprising such a stator assembly
Publication Date: 2019.10.09 SKF MAGNETIC MECHATRONICS SAS
  • EP3073613B1 patent drawingFigure 1~2
  • EP3073613B1 patent drawingFigure 3~4
  • EP3073613B1 patent drawingFigure 5~6

AI summary

This stator assembly (1) comprises a housing (3) and a stator (5) which are concentric, the stator (5) being mounted radially inside the housing (3), the housing (3) having an inner surface (30) and the stator (5) having an outer surface (50) which radially faces the inner surface (30) of the housing (3). One of the outer surface (50) of the stator (5) and the inner surface (30) of the housing (3) has recessed shapes (302; 30a; 56; 58) and the other one of the outer surface (50) of the stator (5) and the inner surface (30) of the housing (3) has protruding shapes (52; 54; 32). The recessed shapes and the protruding shapes are arranged so that in a first relative position of the housing (3) and the stator (5), the protruding shapes are inserted in the recessed shapes so that the stator (5) can be mounted radially inside the housing (3) along a central axis (X-X') of the assembly (1), and in a second relative position of the housing (3) and the stator (5), which is angularly shifted relative to the first position around the central axis (X-X'), the protruding shapes exert, against the one of the housing (3) and the stator (5) which bears the recessed shapes, a radial force (F) which angularly and axially locks the stator (5) with respect to the housing (3).