Electric Downlock Actuator with Lost-Motion Joint

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Solution Overview

Problem

Electrically powered downlock actuation systems face challenges in fitting within the same spatial constraints as hydraulically powered systems, maintaining weight efficiency, and minimizing force inefficiencies when converting rotary motor output to linear motion for landing gear locking mechanisms.

Innovation Solution

The system employs an electrically powered downlock actuator with a rotary output shaft, a connecting output shaft, and a link rod with a lost-motion joint to toggle the linkage between locked and unlocked positions, using an electric motor and gearbox to directly drive the locking mechanism, ensuring efficient operation within existing spatial constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If an electrically powered downlock actuator is used to replace a hydraulic system, then weight is reduced and maintenance is improved, but the device complexity increases due to the need for rotary-to-linear motion conversion mechanisms

Engineering Contradiction:
Improveweight of downlock actuation systemVSAvoidcomplexity of motion conversion mechanism
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The patent replaces the hydraulic mechanical system with an electric motor system. The electric motor directly drives the locking mechanism through rotary motion, eliminating the need for hydraulic fluid, pumps, and complex rotary-to-linear conversion mechanisms. This substitution reduces weight while maintaining functional simplicity.

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

Solution Approach 2:

The patent extracts and eliminates the hydraulic system components (fluid, hoses, pumps) from the downlock actuation system, retaining only the essential electric motor and direct-drive locking mechanism. This extraction reduces overall system complexity while achieving the desired motion.

Inventive Principle:
Principle #2Taking out (Extraction)

2Area of stationary object

If the electric motor directly drives the locking mechanism, then the spatial constraints are satisfied, but force inefficiencies may occur during motion conversion

Engineering Contradiction:
Improvespace occupied by actuation systemVSAvoidforce inefficiency in motion conversion
Core Design Contradiction:
Area of stationary objectVSLoss of energy

Solution Approach 1:

The patent eliminates traditional rotary-to-linear conversion mechanisms (such as screw jacks or rack-and-pinion systems) that cause force inefficiencies. Instead, the electric motor's rotary motion is directly coupled to the locking mechanism through a simplified direct-drive arrangement, minimizing energy loss while fitting within spatial constraints.

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

3Adaptability or versatility

If a lost-motion joint is used in the link rod, then the system allows for longitudinal translation during retraction, but the device complexity increases

Engineering Contradiction:
Improveability to translate during retractionVSAvoidcomplexity of linkage system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent incorporates a lost-motion joint in the link rod that dynamically adapts its state: during landing gear retraction, the joint allows longitudinal translation to accommodate changing distances between components; during locking operations, the joint transitions to a rigid connection to transmit locking forces effectively. This dynamic behavior provides adaptability without requiring complex additional mechanisms.

Inventive Principle:
Principle #15Dynamics

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 allows for reliable and maintainable electrically powered downlock actuation that fits within the same space as hydraulic systems, achieving efficient locking and unlocking of landing gear without significant weight increase or force inefficiencies.

Implementation Method 1

an electric motor coupled to the upper brace; a rotary output shaft coupled to the electric motor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a lost-motion joint, the lost-motion joint being coupled to a connection pin of the second shaft end of the connecting output shaft, wherein the downlock actuator is configured to toggle the linkage

Methodology Applied
Scientific EffectMechanical tolerance and clearance:

Data Source

PatentEP3275782B1Electrically powered downlock actuation system
Publication Date: 2020.07.08 GOODRICH CORP
  • EP3275782B1 patent drawingFigure 1A~1B
  • EP3275782B1 patent drawingFigure 2A~2B
  • EP3275782B1 patent drawingFigure 3A~3B

AI summary

A locking linkage system (200) may comprise a lockable assembly (211) comprising an upper brace (202), a lower brace (204) coupled to the upper brace (202), and a linkage coupled to the upper brace (202) and the lower brace (204). The locking linkage system (200) may further comprise a downlock actuator (212) comprising an electric motor (214) coupled to the upper brace (202), a rotary output shaft (215) coupled to the electric motor (214), a connecting output shaft (218) coupled to the rotary output shaft (215), wherein the connecting output shaft (218) is configured to rotate between a fixed locked position and a fixed unlocked position, and a link rod (220) having a distal end coupled to the linkage and a proximal end comprising a lost-motion joint, the lost-motion joint being coupled to a connection pin of connecting output shaft (218). The downlock actuator (212) may be configured to toggle the linkage, the upper brace (202), and the lower brace (204) between an unlocked position and a locked position.