Aircraft Outflow Valve Flap Pressure Control

Solution Overview

Problem

Existing aircraft pressure control systems require large and costly negative pressure relief valves to prevent cabin collapse during rapid descent or air conditioner failures, which compromises fuselage strength and increases costs.

Innovation Solution

The method involves adjusting outflow valves to direct external air into the cabin during descent when external pressure exceeds internal pressure, potentially eliminating the need for conventional negative pressure relief valves and allowing them to be designed smaller, reducing airflow through existing valves and thus reducing their size and associated costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional negative pressure relief valves are used to prevent cabin collapse during rapid descent, then cabin pressure safety is improved, but valve size increases which compromises fuselage strength and increases costs

Engineering Contradiction:

Improvecabin pressure safetyVSAvoidfuselage strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The outflow valve is designed to perform multiple functions: during normal flight it relieves positive pressure from the cabin, and during rapid descent it directs external air into the cabin to prevent collapse. This multi-functionality eliminates the need for separate large negative pressure relief valves, thereby preserving fuselage strength while maintaining cabin pressure safety.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of using valves that passively open to relieve negative pressure, the invention actively uses the outflow valve to direct external air inward during rapid descent. This inverted approach transforms the outflow valve from a simple pressure relief device into an active pressure control mechanism that prevents cabin collapse.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If conventional negative pressure relief valves are used to prevent cabin collapse, then cabin pressure safety is improved, but valve costs increase

Engineering Contradiction:

Improvecabin pressure safetyVSAvoidvalve cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The outflow valve is designed to perform multiple functions: during normal flight it relieves positive pressure from the cabin, and during rapid descent it directs external air into the cabin to prevent collapse. This multi-functionality eliminates the need for separate large negative pressure relief valves, thereby preserving fuselage strength while maintaining cabin pressure safety.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention merges the functions of positive pressure relief and negative pressure prevention into a single outflow valve system. By combining these functions, the design eliminates the need for additional separate valves, reducing overall system complexity and manufacturing costs while maintaining cabin pressure safety.

Inventive Principle:

Principle #5Merging (Combining)

3Stress or pressure

If outflow valves are adjusted to 90 degree position to compensate for negative pressure, then internal pressure is maintained, but additional airflow requires larger negative pressure relief valves

Engineering Contradiction:

Improveinternal pressureVSAvoidairflow volume

Core Design Contradiction:

Stress or pressureVSQuantity of substance

Solution Approach 1:

Instead of using valves that passively open to relieve negative pressure, the invention actively uses the outflow valve to direct external air inward during rapid descent. This inverted approach transforms the outflow valve from a simple pressure relief device into an active pressure control mechanism that prevents cabin collapse.

Inventive Principle:

Principle #13The other way round (Inversion)

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 approach maintains cabin pressure without the need for large negative pressure relief valves, enhancing fuselage strength and reducing costs while ensuring safe internal pressure during descent and normal flight conditions.

Implementation Method 1

adjusting a flap of at least one outflow valve to a blade position, in which the flap directs air flowing past an outer surface of the craft into the craft to increase the internal pressure, if the external pressure exceeds the internal pressure

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS8876040B2Method for controlling the internal pressure in an aircraft

Publication Date: 2014.11.04 AIRBUS OPERATIONS GMBH

AI summary

The present invention provides a method for controlling an internal pressure in an aircraft or spacecraft, the method comprising the following steps: detecting the internal pressure in the craft and an external pressure Pa outside of the craft and comparing said pressures with each other; and adjusting a flap of at least one outflow valve to a blade position, in which the flap directs air flowing past an outer surface of the craft into the craft to increase the internal pressure, if the external pressure exceeds the internal pressure by a predetermined value during the descent of the craft. The idea, on which the present invention is based, is to assign a double function to the outflow valve: during normal flight the positive pressure in the craft is relieved by means of the outflow valve. During a too steep descent or in case of failure of the air conditioner of the craft, the flap directs air into the craft and thus adapts the internal pressure to the external pressure as soon as it exceeds the internal pressure. Thus, a negative pressure relief valve is advantageously not required and a size thereof can be considerably reduced respectively.