Flow Divider Valves Transient Pressure Limiting

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Solution Overview

Problem

Conventional flow divider valves in aerospace fuel systems face challenges in smoothly transitioning between flow splits, especially at low flow conditions, leading to disturbances and inefficiencies.

Innovation Solution

The system incorporates an equalization bypass valve (EBV) with a pressure equalization solenoid and orifice bypass valve (OBV) to manage pressure differentials and rate limiting orifices, allowing for variable rate control and rapid transitions between equalized and un-equalized modes, minimizing fuel flow disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional flow divider valves are used to control flow split transitions, then the system can maintain stable operation, but the transition speed is slow and disturbances occur especially at low flow conditions

Engineering Contradiction:

Improvetransition speedVSAvoidflow stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The flow control system is segmented into multiple independent pathways: a primary flow path through the EBV with rate limiting orifice, and a secondary bypass path through the OBV. This segmentation allows different portions of flow to be controlled at different rates, enabling faster overall transition while maintaining stability through the controlled primary path.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between restricted flow mode (through EBV and RLO) and bypass flow mode (through OBV) based on operating conditions. The OBV opens during rapid acceleration to provide unrestricted flow path, then closes during steady-state operation, allowing the system to adapt its flow characteristics in real-time.

Inventive Principle:

Principle #15Dynamics

2Reliability

If rate limiting orifices are used to control flow transitions, then flow disturbances are minimized, but upstream over-pressurization occurs during rapid accelerations

Engineering Contradiction:

Improveflow control precisionVSAvoidupstream pressure

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The OBV acts as an intermediary element that provides an alternative flow path around the rate limiting orifice. When upstream pressure becomes excessive during rapid acceleration, the OBV opens to relieve the pressure buildup by allowing fuel to bypass the restrictive RLO, preventing over-pressurization while maintaining flow control capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bypass valve is pre-positioned to open automatically when pressure differential across the RLO reaches a predetermined threshold. This preliminary action occurs before dangerous over-pressurization levels are reached, proactively preventing the harmful condition while maintaining normal flow control during standard operation.

Inventive Principle:

Principle #10Preliminary action

3Loss of time

If the EBV opens quickly to respond to flow split commands, then transition time is reduced, but fuel flow disturbances increase

Engineering Contradiction:

Improvetransition timeVSAvoidflow disturbance level

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The total flow is segmented into controlled portion (through EBV) and uncontrolled portion (through OBV). During rapid transitions, the OBV provides an unrestricted path that allows the EBV to open quickly without causing disturbances, as the bypass path absorbs the transient flow changes that would otherwise disturb the system.

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

This configuration enables faster and more stable flow split transitions, reducing fuel flow disturbances and preventing upstream over-pressurization, particularly during rapid accelerations, thus improving the performance of gas turbine engine fuel systems.

Implementation Method 1

A pressure equalization solenoid (PES) is connected to the EC to selectively connect a servo supply pressure (PFA) conduit and/or a return pressure (PDF) conduit into fluid communication with the EC

Methodology Applied

Scientific EffectElectromagnetic force: Electromagnet

Implementation Method 2

The EBV can include a piston that divides flow between the EC and the flow inlet conduit to apportion flow from the flow inlet conduit to the secondary conduit based on a pressure differential between a flow meter pressure at the flow inlet conduit and a pressure in the EC

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP3889409B1Flow divider valves with transient pressure limiting

Publication Date: 2024.04.24 HAMILTON SUNDSTRAND CORP

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AI summary

A system includes a flow inlet conduit (102) and a primary conduit that branches from the flow inlet conduit (102) for delivering flow to a set of primary nozzles. An equalization bypass valve (EBV) connects between the flow inlet conduit and a secondary conduit for delivering flow to a set of secondary nozzles. The EBV is connected to an equalization conduit (EC). A pressure equalization solenoid is connected to the EC to selectively connect a servo supply pressure conduit and/or a return pressure (PDF) conduit into fluid communication with the EC. An EBV rate limiting orifice (RLO) is connected in the PDF conduit. A bypass conduit branches from the PDF conduit on a first side of the EBV RLO and reconnects to the PDF conduit on a second side of the EBV RLO. An orifice bypass valve (OBV) is connected to the bypass conduit and acts to selectively bypass the EBV RLO.