Aircraft Air Mixing Valve Layout for Ice-Free Backflow Protection

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Solution Overview

Problem

Aircraft air conditioning systems face complexity and increased component count due to separate safety and non-return valves required to prevent icing, leading to higher costs and pressure losses.

Innovation Solution

Integration of a non-return valve within the mixing device eliminates the need for separate components and additional pipes, using triangular pockets with flaps that pivot in warm air flows to remain ice-free and close only in fault conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate safety valve and non-return valve are provided in the pressure frame, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improveprevention of icingVSAvoidcomponent count
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the safety valve and non-return valve functions into a single integrated mixing device. The mixing device includes a first mixing chamber for fresh air, a second mixing chamber for recirculated air, and an integrated non-return valve mechanism that prevents backflow while maintaining cabin pressure. This merging eliminates the need for separate safety and non-return valves in the pressure frame, reducing component count while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If additional pipes are provided for routing circulating air, then reliability is improved, but weight increases

Engineering Contradiction:
Improvepressure maintenanceVSAvoidsystem weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent integrates the circulating air routing function directly into the mixing device structure. The second mixing chamber is positioned to receive recirculated air from the cabin, and the integrated valve mechanism controls air flow without requiring additional external pipes. This integration eliminates unnecessary piping while maintaining pressure maintenance capability, thereby reducing system weight.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If additional pipes are provided for routing circulating air, then reliability is improved, but pressure losses increase

Engineering Contradiction:
Improvepressure maintenanceVSAvoidpressure losses
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent consolidates the air routing function within the mixing device itself, eliminating additional external pipes. The first and second mixing chambers are directly connected to the discharge line, and the integrated valve mechanism controls flow without creating extra resistance. This reduces the number of connections and joints in the air flow path, thereby minimizing pressure losses while maintaining reliable pressure control.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If separate components are used, then reliability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvesystem reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent integrates multiple functions (mixing of fresh and recirculated air, non-return valve operation, and safety pressure maintenance) into a single mixing device assembly. This reduces the total number of components that need to be manufactured, assembled, and tested, thereby lowering manufacturing costs while maintaining system reliability through the integrated design.

Inventive Principle:
Principle #5Merging (Combining)

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

This design results in a compact, cost-effective, and weight-saving system with reduced pressure losses and enhanced reliability through the elimination of redundant components and pipes.

Implementation Method 1

Comparatively warm recirculated air from the aircraft cabin thus surrounds the cold fresh air flowing out of the air conditioning system, so that icing due to the heat transfer from the warm air can be prevented.

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

the warm circulating air from the cabin is routed through the so-called pressure frame into the unpressurized area. The mixed, ice-free air is fed back into the cabin via a non-return valve.

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP1964775B1Mixing device for aircraft air-conditioning system
Publication Date: 2014.04.16 LIEBHERR AEROSPACE LINDENBERG GMBH
  • EP1964775B1 patent drawingFigure 1~2
  • EP1964775B1 patent drawingFigure 3~4
  • EP1964775B1 patent drawingFigure 5~6

AI summary

The invention relates to a mixing device (10) for an aircraft air conditioning system with a supply line for fresh air from the air conditioning system, with a second supply line for recirculated air from a printed area of ​​the aircraft and with a discharge line for supplying mixed air in the printed area of ​​the aircraft, wherein a check valve (12) is integrated in the mixer.