Brake Stack Closure Pressure Determination System

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Solution Overview

Problem

Aircraft brake systems face issues with rapid brake torque onset due to underfilling or overfilling with hydraulic fluid, leading to deceleration overshoot or delayed brake onset and pressure overshoot during stack closure.

Innovation Solution

A brake system that includes a force member, a valve for adjusting fluid pressure, and pressure transducers generating a proportional electrical signal, with processors that modulate fluid pressure based on a waveform signal to determine the stack closure pressure by monitoring the output signal until it equals the commanded pressure, reducing lag and adjusting for changes over time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If hydraulic brake pressure is increased to generate brake torque, then braking force is improved, but deceleration overshoot occurs due to rapid brake torque onset

Engineering Contradiction:

Improvebrake torqueVSAvoiddeceleration control

Core Design Contradiction:

ForceVSEase of operation

Solution Approach 1:

The system performs preliminary action by determining the stack closure pressure in advance through a detection phase where the brake piston is advanced until contact with the brake stack occurs. This pre-determined pressure value is then used as a reference to control subsequent braking operations, preventing rapid torque onset and deceleration overshoot by modulating pressure increase rate based on the pre-acquired closure pressure information.

Inventive Principle:

Principle #10Preliminary action

2Stress or pressure

If hydraulic brake fluid volume is increased to ensure sufficient pressure, then brake torque generation is improved, but pressure overshoot occurs during stack closure

Engineering Contradiction:

Improvehydraulic brake pressureVSAvoidpressure control accuracy

Core Design Contradiction:

Stress or pressureVSMeasurement precision

Solution Approach 1:

The system implements feedback by continuously monitoring the actual fluid pressure in the cylinder using a pressure transducer and comparing it with the commanded pressure from the valve. The control module adjusts the valve command based on the difference between commanded and actual pressure, preventing pressure overshoot during stack closure by dynamically modulating the hydraulic fluid flow to match the desired pressure profile.

Inventive Principle:

Principle #23Feedback

3Device complexity

If conventional brake systems use fixed initial pressure settings, then system simplicity is maintained, but brake onset delay occurs due to incorrect pressure initialization

Engineering Contradiction:

Improvepressure control systemVSAvoidbrake onset delay

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The system performs preliminary action by executing a detection phase before normal braking operations to determine the actual stack closure pressure. This pre-acquired information is stored and used to initialize subsequent braking operations, eliminating brake onset delay caused by incorrect fixed pressure settings while maintaining reasonable system complexity through automated detection and storage of closure pressure values.

Inventive Principle:

Principle #10Preliminary action

4Device complexity

If brake stack closure pressure is not accurately determined, then system simplicity is maintained, but brake torque generation reliability deteriorates

Engineering Contradiction:

Improvepressure detection systemVSAvoidbrake torque generation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system implements feedback by using pressure transducers to continuously monitor actual fluid pressure and comparing it with commanded pressure from the control valve. The control module adjusts valve commands based on the pressure difference feedback, ensuring accurate determination of stack closure pressure and reliable brake torque generation while managing detection system complexity through automated control algorithms.

Inventive Principle:

Principle #23Feedback

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 system effectively sets the initial brake pressure to minimize lag in conventional brake systems, allowing for precise control and adjustment of brake torque, reducing deceleration overshoot and delay, and accounting for wear and fluid volume changes.

Implementation Method 1

one or more pressure transducers that generate a proportional electrical signal representative of the fluid pressure within the cylinder

Methodology Applied

Scientific EffectPressure transduction: Piezoresistive Effect

Data Source

PatentUS11345465B2System for determining the stack closure pressure of a brake stack

Publication Date: 2022.05.31 THE BOEING CO

AI summary

A brake system includes a brake stack having a stack closure pressure, a force member positioned within a cylinder, a valve configured to control fluid pressure of the brake system, and one or more pressure transducers that generate a proportional electrical signal representative of the fluid pressure within the cylinder. The brake system also includes one or more processors in electronic communication with the valve, the one or more pressure transducers, and a memory coupled to the one or more processors. The memory stores data comprising a database and program code that, when executed by the one or more processors, causes the brake system to determine the stack closure pressure of the brake stack.