Negative Pressure Cooling for Electrical Machines

Solution Overview

Problem

Existing cooling systems for electrical machines face challenges in achieving high power density while efficiently managing heat, often resulting in mechanical complexity, noise, and the risk of cooling liquid leakage.

Innovation Solution

A negative relative pressure cooling system is integrated with the electrical machine, utilizing a cooling passageway with an inlet and outlet connected to a vent tank and a liquid-actuated aspirator. This system operates at a pressure less than ambient atmospheric pressure, allowing air to be drawn into the passageway in case of leaks, preventing cooling liquid leakage and enhancing cooling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If positive pressure cooling systems are used to force cooling liquid through passageways, then cooling efficiency is improved, but the risk of cooling liquid leakage increases and mechanical complexity increases

Engineering Contradiction:

Improvecooling efficiencyVSAvoidcooling liquid leakage risk

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent inverts the conventional positive pressure cooling approach by using negative pressure (vacuum) to draw cooling liquid through the passageways. This reversal of the pressure gradient eliminates the risk of liquid leakage while maintaining effective cooling, as the cooling liquid is pulled through the passageways rather than forced through them under positive pressure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent employs pneumatic principles by using a vacuum system to create negative pressure differential that drives the cooling liquid through the passageways. The vacuum pump creates a pressure differential that pulls the cooling liquid from the reservoir through the stator core and teeth, eliminating the need for positive pressure systems that cause leakage.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Temperature

If positive pressure cooling systems are used to force cooling liquid through passageways, then cooling efficiency is improved, but mechanical complexity and noise increase

Engineering Contradiction:

Improvecooling efficiencyVSAvoidmechanical complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent inverts the conventional positive pressure cooling approach by using negative pressure (vacuum) to draw cooling liquid through the passageways. This reversal of the pressure gradient eliminates the risk of liquid leakage while maintaining effective cooling, as the cooling liquid is pulled through the passageways rather than forced through them under positive pressure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent employs pneumatic principles by using a vacuum system to create negative pressure differential that drives the cooling liquid through the passageways. The vacuum pump creates a pressure differential that pulls the cooling liquid from the reservoir through the stator core and teeth, eliminating the need for positive pressure systems that cause leakage.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Temperature

If cooling liquid is forced through passageways at high pressure, then cooling efficiency is improved, but noise increases

Engineering Contradiction:

Improvecooling efficiencyVSAvoidnoise

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The patent inverts the conventional positive pressure cooling approach by using negative pressure (vacuum) to draw cooling liquid through the passageways. This reversal of the pressure gradient eliminates the risk of liquid leakage while maintaining effective cooling, as the cooling liquid is pulled through the passageways rather than forced through them under positive pressure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent employs pneumatic principles by using a vacuum system to create negative pressure differential that drives the cooling liquid through the passageways. The vacuum pump creates a pressure differential that pulls the cooling liquid from the reservoir through the stator core and teeth, eliminating the need for positive pressure systems that cause leakage.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 system effectively prevents cooling liquid leakage by utilizing negative relative pressure, thereby maintaining high cooling efficiency and reducing mechanical complexity and noise, while allowing for enhanced power density in electrical machines.

Implementation Method 1

a negative relative pressure cooling system connected to the cooling passageway and adapted to move cooling liquid through the cooling passageway at a pressure less than the ambient atmospheric pressure

Methodology Applied

Scientific EffectNegative relative pressure: Pressure Gradient

Implementation Method 2

The flow of the motive liquid through the liquid-actuated aspirator, from the first inlet to the outlet, produces a vacuum that draws the cooling liquid and any entrained air towards the second inlet where it mixes with the motive liquid

Methodology Applied

Scientific EffectVenturi effect: Venturi Effect

Data Source

PatentEP3945760B1Negative relative pressure cooling systems

Publication Date: 2025.04.09 GE ENERGY POWER CONVERSION TECHNOLOGY LTD(GB)

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AI summary

A negative relative pressure cooling system for an item of industrial equipment (e.g., an electrical machine or transformer) is described. The item of industrial equipment includes a cooling passageway (2) adapted to cool part of the item of industrial equipment (24). The cooling system (4) is connected to the cooling passageway (2) and adapted to move cooling liquid through the cooling passageway (2) at a pressure less than the ambient atmospheric pressure.