Electro-hydrostatic Actuator Feedback Control for Landing Gear

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Solution Overview

Problem

The existing electro-hydrostatic actuator systems for raising and lowering aircraft landing gear experience significant variations in operation time and hydraulic pressure due to environmental temperature changes and aerodynamic loads, leading to inefficient retraction and extension processes.

Innovation Solution

Implementing a feedback control mechanism that adjusts the discharge pressure of the hydraulic pump by controlling the electric motor's rotational speed and current supply, ensuring consistent target discharge pressure and rotational speed regardless of oil viscosity and leakage conditions, thereby stabilizing the hydraulic actuator's operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If feedback control of electric motor rotational speed is performed, then the electric motor reaches target rotational speed, but the discharge rate of hydraulic pump varies significantly with temperature causing inconsistent actuator operation time

Engineering Contradiction:

Improveelectric motor rotational speedVSAvoidlanding gear retraction/extension time

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The patent implements feedback control by detecting the actual discharge pressure of the hydraulic pump and comparing it with target discharge pressure. The controller adjusts the electric motor's rotational speed based on this pressure feedback to maintain consistent hydraulic actuator operation time across varying temperatures. This resolves the contradiction by using pressure feedback as an additional control parameter beyond motor speed feedback alone.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the control parameter from solely motor rotational speed to include discharge pressure of the hydraulic pump. By monitoring and controlling discharge pressure, the system compensates for temperature-induced viscosity changes in the operation oil that affect pump discharge rate, thereby maintaining consistent actuator operation time despite environmental variations.

Inventive Principle:

Principle #35Parameter changes

2Speed

If feedback control of electric motor rotational speed is performed, then the electric motor reaches target rotational speed, but the pressure in hydraulic actuator becomes too high in low-temperature environments

Engineering Contradiction:

Improveelectric motor rotational speedVSAvoidhydraulic actuator pressure

Core Design Contradiction:

SpeedVSStress or pressure

Solution Approach 1:

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system takes preliminary anti-action by detecting discharge pressure before it becomes excessively high and adjusting motor speed in advance. The feedback control mechanism prevents over-pressurization by reducing motor speed when discharge pressure approaches target levels, particularly in low-temperature conditions where oil viscosity increases and pump discharge rate would otherwise be excessive.

Inventive Principle:

Principle #9Preliminary anti-action

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 maintains consistent hydraulic pressure and operation time for landing gear retraction and extension across varying temperatures and aerodynamic conditions, ensuring efficient and predictable performance within a predetermined range.

Implementation Method 1

an electric motor 31 connected to the hydraulic pump 32

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

a hydraulic pump 32 supplying operation oil to the hydraulic actuator 21 through the hydraulic circuit 33

Methodology Applied

Scientific EffectHydraulic pressure generation: Hydraulic Press

Implementation Method 3

the hydraulic actuator 21 performs an extension or retraction operation, thereby allowing the landing gear to be stored in a landing gear bay or to extend from the landing gear bay

Methodology Applied

Scientific EffectHydraulic actuation: Hydraulic Press

Data Source

PatentEP3241744B1Electro-hydrostatic actuator system for raising and lowering aircraft landing gear

Publication Date: 2018.12.19 SUMITOMO PRECISION PRODUCTS CO LTD

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AI summary

An electro-hydrostatic actuator system (1) for raising/lowering a landing gear (11) of an aircraft includes: at least one hydraulic actuator (21, 22) configured to retract and extend the landing gear (11); a hydraulic circuit (33); a hydraulic pump (32); an electric motor (31); a controller (4) configured to control the operation of the electric motor at receiving a command to retract or extend the landing gear; and a sensor (34) detecting the discharge pressure of the hydraulic pump. The controller, when receiving the command, feeds back the discharge pressure detected by the sensor, and controls the operation of the electric motor such that the discharge pressure of the hydraulic pump reaches a target discharge pressure.