Shut-down Arrangement for Fuel Systems with Delayed Signal Control

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Solution Overview

Problem

Existing shut-down arrangements for fuel control systems face issues with fatigue damage due to fluid hammer-induced pressure spikes during rapid shut-downs, which are undesirable in regular use, and result in a heavy system due to the need for separate control valve arrangements for normal and rapid shut-downs.

Innovation Solution

A shut-down arrangement featuring a control unit that receives a delayed second shut-down signal, allowing the system to gradually reduce fuel supply before shutting off, minimizing pressure spikes and using a single shut-off actuation device to achieve weight savings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a single shut-off actuation device is used for both normal and rapid shut-down, then weight is reduced, but pressure spikes occur during rapid shut-down causing fatigue damage

Engineering Contradiction:

Improveweight of shut-down arrangementVSAvoidpressure spikes causing fatigue damage

Core Design Contradiction:

Weight of moving objectVSObject-affected harmful factors

Solution Approach 1:

The control unit performs preliminary action by gradually reducing fuel supply through the metering device before the shut-off actuation device operates. This preliminary reduction in fuel flow prevents pressure spikes when the shut-off valve closes rapidly, thereby eliminating fatigue damage while maintaining rapid shut-down capability with a single actuation device

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The metering device acts as an intermediary between the fuel pump and the shut-off valve. It mediates the fuel flow reduction process, allowing the system to gradually decrease fuel supply before the final shut-off action, thus preventing pressure spikes while enabling rapid response

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If separate control valve arrangements are used for normal and rapid shut-down, then shut-down performance is optimized, but system weight increases

Engineering Contradiction:

Improveshut-down performanceVSAvoidweight of shut-down arrangement

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

The single shut-off actuation device is designed with multi-functionality, serving both normal shut-down and rapid shut-down operations. The control unit manages different shut-down modes by controlling the metering device and timing the actuation device operation, allowing one device to perform multiple functions that previously required separate valve arrangements

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses dynamic control through the control unit that adjusts the operation of the metering device and shut-off actuation device based on the required shut-down mode. The delay means dynamically times the actuation device response, enabling the same physical device to achieve different shut-down characteristics (normal vs rapid) as needed

Inventive Principle:

Principle #15Dynamics

3Weight of moving object

If rapid shut-down mode is used for all engine shut-down events, then weight is saved, but fatigue damage occurs from pressure spikes during regular use

Engineering Contradiction:

Improveweight of shut-down arrangementVSAvoidfatigue damage from pressure spikes

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes operational parameters dynamically - during normal shut-down, the metering device gradually reduces fuel flow parameters, while during rapid shut-down, the shut-off actuation device quickly closes the valve. The delay means adjusts timing parameters to coordinate these actions, allowing the same hardware to safely perform both operational modes without fatigue damage

Inventive Principle:

Principle #35Parameter changes

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 solution reduces the risk of fatigue damage while maintaining rapid engine shut-down capabilities, achieving weight savings and ensuring safety in emergency situations, with the delayed shut-down also enhancing flexibility in fuel system checks.

Implementation Method 1

high pressure spikes may occur in parts of the fuel system, resulting from the well known phenomenon of fluid hammer

Methodology Applied

Scientific EffectFluid hammer: Fluid Hammer

Data Source

PatentUS8733398B2Shut-down arrangement

Publication Date: 2014.05.27 ROLLS ROYCE PLC

AI summary

A shut-down arrangement comprises a shut-off actuation device operable under the control of a control unit, a switch whereby a first shut-down signal can be supplied to the control unit and whereby a second shut-down signal can be supplied to the shut-off actuation device, and delay means whereby the transmission of the second shut-down signal to the shut-off actuation device is delayed relative to the transmission of the first shut-down signal to the control unit.