Ceramic Sleeve Stabilizes Ironless Stator Winding at 550°C

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Solution Overview

Problem

Existing electric motors for high-temperature applications face deformation issues due to stoved enamel softening, compromising the air gap and stability, especially in aerospace and oil industry applications, leading to complex and costly designs with frequent maintenance needs.

Innovation Solution

A hollow-cylindrical supporting sleeve made of ceramic material, such as zirconium oxide, is radially positioned inside the stator winding to maintain its shape, combined with a ceramic potting compound for additional stability and heat dissipation, and a soft-magnetic return for optimal heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a hollow-cylindrical ironless stator winding made of stoved-enamel wire is used, then the motor can operate at high temperatures, but the stoved enamel becomes soft and causes winding deformation

Engineering Contradiction:

Improveoperating temperatureVSAvoidwinding dimensional stability

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

A hollow-cylindrical supporting sleeve made of high-temperature stable material (such as ceramic or graphite) is introduced as an intermediary component between the rotor and the stator winding. This supporting sleeve maintains the air gap and provides mechanical support to the stator winding, preventing deformation when the stoved enamel softens at high temperatures.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If a ceramic sleeve is added to maintain air gap and enable cooling, then winding stability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvewinding shape stabilityVSAvoidmotor structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The hollow-cylindrical supporting sleeve is designed to perform multiple functions simultaneously: it maintains the air gap between rotor and stator, provides mechanical support to prevent winding deformation, and serves as a flow channel for cooling medium circulation. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Stability of the object's composition

If active cooling system with oil circuit is implemented, then winding deformation is prevented, but maintenance requirements and operating costs increase

Engineering Contradiction:

Improvewinding dimensional stabilityVSAvoidmaintenance frequency

Core Design Contradiction:

Stability of the object's compositionVSEase of repair

Solution Approach 1:

The supporting sleeve structure enables passive cooling through its hollow cylindrical design that allows cooling medium to flow through the air gap region. This self-service cooling approach reduces reliance on complex active cooling systems with pumps and controls, thereby decreasing maintenance requirements.

Inventive Principle:

Principle #25Self-service

4Stability of the object's composition

If stator winding is wound onto slotted core stack, then winding stability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvestator winding stabilityVSAvoidmanufacturing simplicity

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the slotted core stack from the motor design, adopting a hollow-cylindrical ironless stator winding instead. By removing the complex slotted core structure, manufacturing is simplified while the hollow supporting sleeve provides the necessary mechanical stability to prevent winding deformation at high temperatures.

Inventive Principle:

Principle #2Taking out (Extraction)

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 ensures the electric motor maintains stability and functionality at temperatures up to 550°C or higher, simplifying manufacturing, reducing maintenance, and preventing deformation, while maintaining a stable air gap and efficient heat dissipation.

Implementation Method 1

The hollow-cylindrical stator winding (4) is supported by a hollow-cylindrical supporting sleeve (6) made of a ceramic material, such as zirconium oxide, which lies radially inside against the stator winding (4)

Methodology Applied

Scientific EffectThermal stability:

Implementation Method 2

a soft-magnetic return for optimal heat transfer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

The stator winding normally consists of several rhombic individual windings that overlap in the circumferential direction. The stator winding is here wound from stoved-enamel wire which, after it has cured, takes care that the stator winding remains dimensionally stable.

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS8946962B2Electric motor for high-temperature applications

Publication Date: 2015.02.03 MAXON MOTOR AG

AI summary

An electric motor for high-temperature applications. The electric motor includes a rotor and a stator with a hollow-cylindrical, ironless stator winding of stoved-enamel wire. Furthermore, a soft-magnetic return is provided which encloses the stator winding. The stator winding is supported by a hollow-cylindrical supporting sleeve lying radially inside against the stator winding.