Brake Caliper Heatsink Using Phase Change to Prevent Overheat

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Solution Overview

Problem

Helicopter rotor brakes face overheating issues during emergency braking, leading to potential hydraulic fluid ignition and increased weight due to oversized heatsinks, which compromise performance and safety.

Innovation Solution

A heatsink with a hollow base and intermediate material that melts between 520 Kelvin and 575 Kelvin, surrounded by a refractory housing, featuring external and internal fins for efficient heat dissipation, reducing the size and weight of the braking system while preventing fluid ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heatsink is sized to dissipate four times the nominal braking energy for emergency braking, then the external surface temperature does not exceed fluid ignition temperature, but the heatsink requires significantly greater volume and weight

Engineering Contradiction:
Improveexternal surface temperature of brakeVSAvoidweight of heatsink and brake calliper
Core Design Contradiction:
TemperatureVSWeight of stationary object

Solution Approach 1:

The patent utilizes the phase transition (melting) of an intermediate material positioned between the brake calliper and heatsink base. This material absorbs thermal energy through latent heat of fusion, preventing heat transfer to the heatsink base and maintaining external surface temperatures below fluid ignition temperature without requiring oversized heatsink dimensions

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The intermediate material acts as a thermal intermediary or mediator between the brake calliper and heatsink base. It intercepts and absorbs thermal energy during emergency braking, protecting the heatsink structure from excessive heat while enabling compact design

Inventive Principle:
Principle #24Intermediary (Mediator)

2Weight of stationary object

If the heatsink is made compact to reduce weight, then the installation becomes easier, but the ability to dissipate heat during emergency braking is insufficient

Engineering Contradiction:
Improveweight of heatsinkVSAvoidheat dissipation capacity
Core Design Contradiction:
Weight of stationary objectVSLoss of energy

Solution Approach 1:

The intermediate material's phase transition from solid to liquid absorbs large amounts of thermal energy through latent heat of fusion. This enables compact heatsink design while maintaining sufficient heat dissipation capacity during emergency braking, as the phase change material handles the thermal load that would otherwise require large heatsink surface area

Inventive Principle:
Principle #36Phase transitions

3Object-affected harmful factors

If refractory materials are used to isolate the brake, then fluid ignition is prevented, but the internal parts of the brake reach higher temperatures reducing performance and reliability

Engineering Contradiction:
Improvefluid ignition preventionVSAvoidreliability of internal brake parts
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The intermediate material serves as a thermal intermediary that protects internal brake parts from excessive heat. It absorbs thermal energy during emergency braking, preventing heat transfer to the brake calliper and internal components, thereby maintaining their temperature within safe operating limits and preserving reliability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The phase transition of the intermediate material absorbs large amounts of heat energy, creating a thermal barrier that protects internal brake parts from reaching temperatures that would compromise their performance and reliability

Inventive Principle:
Principle #36Phase transitions

4Object-affected harmful factors

If refractory isolation is used to prevent fluid ignition, then safety is improved, but the brake takes longer to cool down delaying engine restart

Engineering Contradiction:
Improvefluid ignition preventionVSAvoidcooling down time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The intermediate material undergoes phase transition from solid to liquid, absorbing large amounts of thermal energy through latent heat of fusion. This rapid heat absorption enables the brake system to cool down quickly after emergency braking, allowing faster engine restart while still preventing fluid ignition

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The intermediate material acts as a thermal mediator that facilitates rapid heat removal from the brake system. By absorbing thermal energy during phase change, it accelerates the cooling process compared to passive refractory isolation

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively manages thermal energy during emergency braking by absorbing heat through latent fusion, preventing fluid ignition and reducing the heatsink's bulk, thus enhancing safety and performance without the need for oversized cooling systems.

Implementation Method 1

the intermediate material melts to absorb thermal energy from the brake calliper

Methodology Applied
Scientific EffectLatent fusion heat: Latent Heat

Implementation Method 2

the intermediate material is configured to melt so as to absorb thermal energy from the brake calliper

Methodology Applied
Scientific EffectPhase change: Phase Change

Implementation Method 3

The heatsink is therefore sized in order to be able to dissipate four times the nominal braking energy

Methodology Applied
Scientific EffectHeat dissipation: Heat Sink

Data Source

PatentEP3650340B1Rotor brake overheat management device
Publication Date: 2021.10.20 RATIER FIGEAC SAS
  • EP3650340B1 patent drawingFigure 1
  • EP3650340B1 patent drawingFigure 2
  • EP3650340B1 patent drawingFigure 3A~3B

AI summary

A heatsink (310) for a brake calliper is provided. The heatsink (310) includes a hollow base (315) and an intermediate material (317) provided in the hollow base (315), the intermediate material being preferably configured to melt above a certain temperature to transport heat from the beake caliper.