Wheel Brake Actuator Liquid Cooling for Low-Speed Motor Heat

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Solution Overview

Problem

Existing air cooling systems for electro-mechanic wheel brake actuators are inefficient at low speeds due to low air velocities and high bulk air temperatures, leading to insufficient heat removal and reduced wear-resistance of electrical components.

Innovation Solution

A cooling system utilizing a liquid or gaseous coolant with a cooling jacket and channels to enhance heat dissipation, combined with a controller for temperature regulation, ensuring efficient cooling even at low speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If air cooling system is used for the electric motor, then the cooling system is simple in structure, but the cooling efficiency is insufficient at low speeds due to low air velocities and high bulk air temperatures

Engineering Contradiction:
Improvecooling system structureVSAvoidcooling efficiency
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent transitions from air cooling to liquid cooling by introducing a cooling circuit with coolant channels. The cooling circuit includes inlet and outlet ports for coolant flow, and channels formed in the stator and/or rotor to enable efficient heat transfer from the electric motor components to the circulating coolant, thereby resolving the insufficient cooling efficiency at low speeds.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the cooling medium from gas (air) to liquid (coolant), fundamentally altering the heat transfer parameters. The liquid coolant provides superior heat capacity and thermal conductivity compared to air, enabling effective cooling even when vehicle speed and air flow are low.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If air cooling is used, then the system requires no additional cooling fluid infrastructure, but heat removal is significantly limited due to low convection coefficient at low speeds

Engineering Contradiction:
Improvecooling system implementationVSAvoidheat removal efficiency
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent implements a hydraulic cooling system with a cooling circuit that circulates liquid coolant through channels in the electric motor. This system actively manages heat removal by pumping coolant through the stator and rotor, ensuring consistent heat dissipation regardless of vehicle speed or air convection conditions.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Device complexity

If conventional air cooling is used, then the cooling system has low component count, but the wear-resistance of electrical motors decreases due to high temperatures

Engineering Contradiction:
Improvecooling system componentsVSAvoidwear-resistance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces a liquid coolant circulation system with cooling channels integrated into the stator and rotor. This hydraulic cooling approach maintains lower operating temperatures of the electric motor components, thereby preserving wear-resistance and extending component life, especially during low-speed operation when air cooling is ineffective.

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

Improves cooling efficiency and wear-resistance of wheel brake actuators by effectively managing heat dissipation through controlled fluid flow, particularly at low speeds.

Implementation Method 1

the efficiency of the air cooling systems for the wheel brake actuators is limited by the air convection which depends directly on the air circulation

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

a cooling system for a cooling fluid to cool one or more parts of the electric motor

Methodology Applied
Scientific EffectConduction (thermal): Conduction (thermal)

Implementation Method 3

the cooling system comprises a cooling layer which is arranged on one or more parts of the electric motor to cool down the electric motor due to evaporating of the cooling fluid supplied to the cooling layer

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3627667B1Wheel brake actuator and method of controlling a cooling system of an electric motor
Publication Date: 2025.09.03 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH
  • EP3627667B1 patent drawingFigure 1~2
  • EP3627667B1 patent drawingFigure 3~4

AI summary

The present invention relates to an electric motor for actuating a wheel brake actuator, the electric motor including a stator and a rotor, wherein the electric motor further comprises a cooling system for a liquid coolant to cool one or more parts of the electric motor. The present invention further relates to a wheel brake actuator comprising an electric motor and method of controlling of a cooling system of an electric motor for actuating a wheel brake actuator.