Transfer Valve Backup Switching for Parallel Electrohydraulic Servo Valves

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Solution Overview

Problem

Conventional hydraulic control systems for aircraft actuators require two full-sized electrohydraulic servo valves (EHSVs) for normal and backup operations, which are cumbersome and inefficient, necessitating a more effective backup and control mechanism.

Innovation Solution

A system utilizing two parallel electrohydraulic servo valves with a single transfer valve and solenoid valves to switch between them, allowing for normal operation with combined power and backup modes using a single functional EHSV in case of failure, reducing actuator weight, envelope, and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two full-sized electrohydraulic servo valves are used for normal and backup operations, then reliability is improved, but device complexity and weight increase

Engineering Contradiction:

Improvebackup operation reliabilityVSAvoidvalve system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the backup system into modular components: two parallel EHSVs with individual control, and a transfer valve with multiple positions. This segmentation allows independent operation of each EHSV and simplifies the backup switching mechanism, reducing overall system complexity while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The transfer valve serves multiple functions: it connects both EHSVs to the actuator during normal operation, isolates failed EHSVs during backup mode, and enables seamless switching between valves. This multi-functionality eliminates the need for separate backup-specific components, reducing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If two full-sized electrohydraulic servo valves are used for normal and backup operations, then reliability is improved, but weight increases

Engineering Contradiction:

Improvebackup operation reliabilityVSAvoidactuator weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges the backup functionality into the existing EHSV infrastructure by using parallel connection of two standard EHSVs with a transfer valve. This approach eliminates the need for separate backup valve assemblies, reducing overall weight while maintaining full backup capability.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If two full-sized electrohydraulic servo valves are used for normal and backup operations, then backup capability is improved, but leakage increases

Engineering Contradiction:

Improvebackup capabilityVSAvoidhydraulic leakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The transfer valve extracts and isolates the failed EHSV from the hydraulic circuit during backup operation. By blocking the connection between the failed valve and the actuator, the system prevents leakage from the failed EHSV while maintaining clean operation through the functional valve.

Inventive Principle:

Principle #2Taking out (Extraction)

4Adaptability or versatility

If a transfer valve and transfer EHSV/solenoid are used for switching between EHSVs, then backup switching is enabled, but device complexity increases

Engineering Contradiction:

Improvebackup switching capabilityVSAvoidswitching mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The transfer valve acts as an intermediary component that mediates between the two EHSVs and the actuator. It provides a centralized control point for switching and isolation, simplifying the overall switching mechanism while enabling versatile backup operation modes.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enables efficient and reduced-power operation of actuators by disconnecting failed EHSVs and utilizing the remaining one, thereby minimizing weight, size, and leakage, while maintaining reliable actuator functionality.

Implementation Method 1

A first solenoid valve can be operatively connected to actuate the spool of the transfer valve

Methodology Applied

Scientific EffectSolenoid: Solenoid

Implementation Method 2

a first electrohydraulic servo valve (EHSV) configured to be in fluid communication with a pressure supply and with a pressure return

Methodology Applied

Scientific EffectElectrohydraulic conversion:

Data Source

PatentUS12163537B1Three way transfer valve for parallel electrohydraulic servo valve control of actuator

Publication Date: 2024.12.10 HAMILTON SUNDSTRAND CORP

AI summary

A method includes using two parallel electrohydraulic servo valves EHSVs with a single transfer valve to move an actuator during a normal operation mode. The method includes upon failure of one of the EHSVs, using the single transfer valve to disconnect a non-operational one of the EHSVs and continuing to move the actuator with a functional one of the EHSVs in a backup mode.