Hydraulic Control System for Thrust Reversal and Variable Nozzle
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Solution Overview
Problem
The existing control architectures for turbojet engine nacelles with thrust reversal and variable nozzle devices face challenges in using single-action cylinders due to aeronautical safety and segregation criteria, which complicates the implementation of both functions while maintaining safety standards.
Innovation Solution
A hydraulic control system that segregates control modes between thrust reversal and variable nozzle operations, allowing the use of single-action actuators by providing mechanical synchronization and fluid communication between cylinders, along with a central control unit and redundant valve systems to ensure safety and availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If single-action cylinders are used to control both thrust reversal and variable nozzle devices, then the bulk and mass of the nacelle are reduced, but aeronautical safety standards and control segregation criteria cannot be met
Solution Approach 1:
The control system is segmented into two distinct control units: a first control unit dedicated to thrust reversal mode and a second control unit dedicated to variable nozzle mode. This segmentation allows each control unit to independently manage its respective function while maintaining aeronautical safety standards, eliminating the need for complex segregated control lines that would otherwise be required when using single-action cylinders for both functions.
Solution Approach 2:
Single-action cylinders are designed to perform multiple functions by being controlled by different control units in different operational modes. The same physical cylinder can control either the thrust reversal device or the variable nozzle device depending on which control unit is active, thereby reducing nacelle mass while maintaining safety through logical control segregation rather than physical segregation.
2Device complexity
If single-action cylinders are used for both functions, then the device complexity is reduced, but control segregation and availability criteria are compromised
Solution Approach 1:
The control system is divided into separate control units for thrust reversal and variable nozzle functions. Each control unit manages specific valves and cylinders independently, reducing overall system complexity by eliminating the need for complex segregated control lines while maintaining functional availability through independent control paths.
Solution Approach 2:
The system dynamically switches between control modes by activating different control units based on operational requirements. The first control unit activates for thrust reversal operations while the second control unit activates for variable nozzle operations, allowing the same physical infrastructure to serve multiple functions without compromising availability.
3Adaptability or versatility
If double-action cylinders with double rods are used, then both functions can be controlled, but the bulk and mass of the nacelle increase
Solution Approach 1:
Single-action cylinders are designed to universally control both thrust reversal and variable nozzle functions by switching between control units. Instead of requiring separate double-action cylinders for each function, the same single-action cylinders perform both roles, significantly reducing nacelle mass while maintaining full functional capability through the dual control unit architecture.
Solution Approach 2:
The control system merges the functionality of what would traditionally require separate double-action cylinders into a unified system using single-action cylinders controlled by two different control units. This merging reduces the number of actuators and associated infrastructure needed in the nacelle, reducing mass and bulk while preserving all required functions.
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 the use of single-action cylinders for both thrust reversal and variable nozzle functions while meeting aeronautical safety standards, enhancing system availability and reliability through segregated control and mechanical synchronization.
Implementation Method 1
A hydraulic control system that segregates control modes between thrust reversal and variable nozzle operations, allowing the use of single-action actuators by providing mechanical synchronization and fluid communication between cylinders
Data Source
Figure 1
AI summary
The present invention relates to a hydraulic control system for a thrust reversal device installed on a jet engine nacelle and combined with a nozzle variation device, which includes at least one mobile cowl translated by a plurality of mutually synchronised single-action actuators (1d, 1g), said hydraulic control system including at least one unit (100d, 100g) for controlling the cylinders according to a variable nozzle mode, and at least one unit (200) for controlling the cylinders according to a thrust reversal mode, characterised in that the control system includes at least one additional regulation unit (400) hydraulically interconnecting the cylinders and including a plurality of control valves (401, 402).