Hydraulic Pressure Switch for Thrust Reverser Control

Solution Overview

Problem

Conventional pressure switches in thrust reverser systems are either too insensitive to detect low pressures due to high response thresholds set to avoid false triggers from momentary transients, or they fail to detect high absolute pressures, which can indicate return line blockages, posing safety risks if not detected in flight.

Innovation Solution

A hydraulically controlled pressure switch with a spool configured to respond to both control and return pressures, utilizing different end shapes/sizes to create force biases, allowing detection of small differentials or high absolute pressures while avoiding responses to normal pressure transients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If absolute pressure switches are set to have a high response threshold to avoid false triggers from momentary transients, then false triggers are reduced, but low control pressures are not detected

Engineering Contradiction:

Improveavoidance of false triggersVSAvoiddetection of low control pressures

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The pressure switch function is segmented into two independent detection paths: an absolute pressure detection path (via the first pressure port and first spring) and a differential pressure detection path (via the second pressure port and second spring). This segmentation allows each path to be optimized for its specific detection purpose without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pressure switch is designed with multi-functionality to detect both absolute pressure (for high pressure blockage detection) and differential pressure (for low pressure control detection), making it a universal monitoring device that handles multiple pressure monitoring scenarios within a single component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If differential pressure switches are used to avoid responding to momentary transients, then response to transients is avoided, but high absolute pressure throughout the system is not detected

Engineering Contradiction:

Improveavoidance of false triggersVSAvoiddetection of high absolute pressure

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The pressure switch function is segmented into two independent detection paths: an absolute pressure detection path (via the first pressure port and first spring) and a differential pressure detection path (via the second pressure port and second spring). This segmentation allows each path to be optimized for its specific detection purpose without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pressure switch is designed with multi-functionality to detect both absolute pressure (for high pressure blockage detection) and differential pressure (for low pressure control detection), making it a universal monitoring device that handles multiple pressure monitoring scenarios within a single component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If pressure switch response threshold is increased to filter out normal pressure transients, then false triggers from transients are reduced, but sensitivity to real pressure changes is decreased

Engineering Contradiction:

Improvestability against normal transientsVSAvoidsensitivity to pressure changes

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The pressure switch function is segmented into two independent detection paths: an absolute pressure detection path (via the first pressure port and first spring) and a differential pressure detection path (via the second pressure port and second spring). This segmentation allows each path to be optimized for its specific detection purpose without compromising the other.

Inventive Principle:

Principle #1Segmentation

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 improved switch effectively detects pressure changes indicative of system issues, such as leaks or blockages, reducing false triggers and ensuring safe operation by being sensitive to differential and absolute pressures without reacting to normal transients, thus enhancing safety and reliability.

Implementation Method 1

The pressure switch comprises a hydraulic spool that responds to control line pressure to drive a spring loaded target into range of a pair of proximity switches

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

The proximity switches respond to proximity of the target as it is moved by a sufficiently high control pressure against the force of the spring

Methodology Applied

Scientific EffectProximity sensing:

Data Source

PatentEP2966287B1Pressure switch for thrust reverser control

Publication Date: 2019.08.28 GOODRICH ACTUATION SYST

Figure 1
Figure 2

AI summary

A hydraulically controlled pressure switch, comprising a spool 1' having an elongate body with a first end 7'a and a second end 7'b, and an intermediate part between the two ends; a target 3' movably connected to the second end of the spool by means of a spring 2'; means 4' for detecting movement of the target and providing an indication of pressure acting on the spool based on the movement of the target; whereby the spool is configured to cause movement of the target against the means of the spring based on the level of pressure 5' acting against the first end, towards the spring, and also the level of pressure 6' at the intermediate part between the two ends.