Hydraulic Servo Actuator Command Transmission With Three-Channel Redundancy

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Solution Overview

Problem

Current flight control systems in helicopters face issues with mechanical connections between controls and hydraulic actuators, leading to potential loss of control in case of flight control computer or electrical transmission failure, and require a space-saving electric architecture with high availability.

Innovation Solution

An electromechanical architecture that transmits electrical commands to hydraulic actuators using a system with three channels of rotary and linear electric actuators, each connected to a control device, ensuring high availability and reducing mechanical circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical connections are used between controls and hydraulic actuators, then control reliability is maintained, but system complexity and pilot effort increase

Engineering Contradiction:
Improvecontrol reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical connections between controls and hydraulic actuators with an electromechanical system. Electrical commands from the flight control computer are transmitted to electric actuators, which then mechanically drive the hydraulic actuators. This substitution eliminates complex mechanical linkages while maintaining control reliability through the redundant three-channel architecture.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electric actuators as intermediary components between the flight control computer and hydraulic actuators. These electric actuators receive electrical commands and convert them to mechanical motion to drive the hydraulic actuators, serving as a mediating layer that eliminates direct mechanical connections while preserving control functionality.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If three-channel electromechanical system is implemented, then control availability is guaranteed, but system footprint increases

Engineering Contradiction:
Improvecontrol availabilityVSAvoidsystem footprint
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the three control channels into a single integrated electromechanical actuator assembly. The three electric actuators (first rotary, second rotary, and linear) are combined to drive a single hydraulic actuator, sharing common mechanical connections and control electronics, thereby reducing overall system footprint while maintaining control availability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent designs the electromechanical actuator assembly with multi-functional capability, where the same mechanical connections and structural components serve all three control channels. The electric actuators can independently or collectively drive the hydraulic actuator, providing universal functionality that reduces redundant components and minimizes system footprint.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If electrical transmission replaces mechanical transmission, then pilot effort is reduced, but control reliability decreases

Engineering Contradiction:
Improvepilot effortVSAvoidcontrol reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent segments the control system into three independent control channels, each with its own electric actuator and control path. This segmentation allows the system to maintain electrical transmission benefits (reduced pilot effort) while improving reliability through redundancy - if one channel fails, the other two can still provide control authority.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements beforehand cushioning by designing the three-channel electromechanical system with redundant control paths before any failure can occur. The system is pre-configured with multiple independent channels that can compensate for failures, ensuring control reliability is maintained even when electrical transmission components fail.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

Eliminates mechanical connections, reduces pilot effort, maintains hydraulic actuator functionality, and guarantees control availability even in case of channel failure, while minimizing system footprint.

Implementation Method 1

a rotary electric actuator (211) comprising a first channel (211a) comprising a motor (a1), and a second channel (211b) comprising a motor (b1)

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

a linear electric actuator (212) comprising a third channel (212c) comprising a motor (c1)

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 3

at least one hydraulic servo actuator (30)

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4448383B1Command transmission system to a hydraulic servo actuator
Publication Date: 2025.09.10 SAFRAN ELECTRONICS & DEFENSE (FR)
  • EP4448383B1 patent drawingFigure 1
  • EP4448383B1 patent drawingFigure 2
  • EP4448383B1 patent drawingFigure 3~4

AI summary

One aspect of the invention relates to a system (20) for transmitting commands to at least one hydraulic servo actuator (30), comprising: - a mechanical system (21) including: o a rotary electrical actuator (211) comprising a first and a second channel (211a, 211b), o a linear electrical actuator (212) comprising a third channel (212c), the linear electrical actuator (212) being connected to the rotary electrical actuator (211) by a mechanical connection (213) and being connected to the hydraulic servo actuator (30) by a mechanical connection (214); - a control system (22) including: o a first control device (221) connected via an electrical connection to the first channel (211a); o a second control device (222) connected via an electrical connection to the second channel (211b); o a third control device (223) connected via an electrical connection to the third channel (212c).