Hydraulic Valve Orifice Layout for Slew Rate Limiting

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Solution Overview

Problem

Existing fluid flow systems in applications like gas turbine engines face challenges in maintaining adequate fluid flow and controlling slew rates under varying pressure conditions, often leading to undesirably high slew rates that can exceed predetermined thresholds.

Innovation Solution

Incorporating fixed orifices between the electromechanical interface device (EMID) and the metering valve to limit the pressure differential and flow rate, ensuring the slew rate remains within a safe range by sizing the orifices to restrict fluid flow accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the EMID meters fluid from high-pressure and low-pressure sources to control the metering valve, then fluid flow control is improved, but the slew rate may exceed predetermined thresholds under certain conditions

Engineering Contradiction:
Improvefluid flow controlVSAvoidslew rate control
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

A fixed orifice is introduced as an intermediary component between the EMID and the metering valve. This orifice acts as a flow restriction that limits the maximum rate at which fluid can reach the metering valve, thereby preventing slew rate from exceeding predetermined thresholds while still allowing the EMID to maintain fluid flow control through pressure differential adjustment

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If fixed orifices are added to limit pressure differential and flow rate, then slew rate control is improved, but device complexity increases

Engineering Contradiction:
Improveslew rate controlVSAvoidsystem structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fixed orifice is designed with a specific aperture size that changes the flow characteristics of the system. By carefully selecting the orifice dimension, the system achieves predetermined slew rate limiting without requiring complex control mechanisms, maintaining simplicity while improving reliability

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 effectively prevents slew rates from exceeding predetermined thresholds, enhancing the reliability and safety of the fluid flow system while reducing costs and weight, and can be applied to various fluid control applications beyond fuel supply systems.

Implementation Method 1

A fixed orifice arrangement is disclosed for limiting the slew rate of a metering valve

Methodology Applied
Scientific EffectFluid flow restriction through orifice: Pressure Drop

Data Source

PatentUS20230160349A1Hydraulically rate limited valve
Publication Date: 2023.05.25 HAMILTON SUNDSTRAND CORP
  • US20230160349A1 patent drawing
  • US20230160349A1 patent drawing
  • US20230160349A1 patent drawing

AI summary

A fluid flow system includes a main valve having a spool, a first chamber, and a second chamber. A pressure difference between the first chamber and the second chamber is configured to move the spool to control fluid flow. An electromechanical meter interface device (EMID) is in fluid communication with at least one of the first and second chambers of the main valve. The EMID is configured to meter fluid from a first source and a second source to the at least one of the first chamber and the second chamber. The first source has a different pressure from the second source. A fixed orifice is arranged between the main valve and the EMID. A fuel system for a gas turbine engine is also disclosed.