Electric Track Lock for Thrust Reverser Safety

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Solution Overview

Problem

Current thrust reverser actuation systems require manual inhibition of movable parts during maintenance, which is unsafe and inefficient, and existing locking mechanisms are bulky, heavy, and complex, relying on large solenoids and reduction gearboxes.

Innovation Solution

A lightweight and compact track lock system using a pawl assembly with a compliant member and position lock assembly that mechanically locks the slider assembly, utilizing motion to actuate the tertiary lock instead of electrical power, and includes sensors for indication of lock positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual inhibition of movable parts is used during maintenance, then the system is simple to operate, but safety is compromised and efficiency is reduced

Engineering Contradiction:
ImprovesafetyVSAvoidlocking mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism automatically engages and disengages based on the position of the movable element, eliminating the need for manual intervention. The system self-locks when the movable element reaches a predetermined position and self-unlocks when reversed, providing safety without requiring manual operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical inhibition with an automated locking mechanism that uses a locking element and cam surface to automatically secure the movable element in position, transitioning from human-operated mechanical inhibition to an automated mechanical locking system.

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

2Reliability

If traditional locking mechanisms with large solenoids and reduction gearboxes are used, then the locking function is reliable, but the system becomes bulky and heavy

Engineering Contradiction:
Improvelocking function reliabilityVSAvoidlocking mechanism weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent extracts and eliminates the large solenoid and reduction gearbox from the locking mechanism, retaining only the essential locking function through a simplified design that uses a locking element, cam surface, and spring, thereby significantly reducing weight while maintaining reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the operational parameters of the locking mechanism by using a spring-based system with a cam surface instead of an electrically-driven reduction gearbox, altering the force application method from high-torque mechanical reduction to cam-based mechanical advantage, which reduces the overall size and weight of the system.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If traditional locking mechanisms with large solenoids are used, then the locking function is reliable, but the device complexity increases

Engineering Contradiction:
Improvelocking function reliabilityVSAvoidlocking mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the large solenoid from the locking mechanism, retaining only the essential locking components (locking element, cam surface, spring), thereby simplifying the device architecture while preserving the core locking function through passive mechanical means.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The locking mechanism operates automatically based on the position of the movable element, with the spring providing the necessary force to engage or disengage the locking element as the cam surface rotates, eliminating the need for complex electrical control systems.

Inventive Principle:
Principle #25Self-service

4Speed

If electrical power is used to actuate the locking mechanism, then the response is fast, but power consumption increases

Engineering Contradiction:
Improvelocking actuation speedVSAvoidpower consumption
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The patent replaces the electrically-actuated locking mechanism with a passive mechanical system that uses the motion of the movable element itself to drive the cam surface and engage or disengage the locking element, eliminating power consumption while maintaining rapid response through direct mechanical coupling.

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

Solution Approach 2:

The locking mechanism uses the kinetic energy and motion of the movable element to automatically engage or disengage the lock, with the spring providing the necessary restoring force, thereby eliminating the need for external electrical power while maintaining fast actuation speeds through direct mechanical energy transfer.

Inventive Principle:
Principle #25Self-service

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

The system prevents inadvertent in-flight deployment, reduces bulk and weight, and lowers power consumption by using mechanical motion to lock the slider assembly, providing a safer and more efficient locking mechanism.

Implementation Method 1

a compliant member configured to urge rotation of the pawl assembly about the pawl axis from a pawl locked position, such that the pawl arm is engaged in the slot and the pawl cam is disengaged from a slider cam extending from the slider assembly

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3307623B1Electric track lock
Publication Date: 2019.04.24 WOODWARD INC
  • EP3307623B1 patent drawingFigure 1~2
  • EP3307623B1 patent drawingFigure 3~4
  • EP3307623B1 patent drawingFigure 5~6

AI summary

A track lock assembly (100) includes a pawl assembly (110) comprising a pawl arm (112) extending from a pawl axis (116) and configured to engage a slot (20) in a slider assembly (10), a cam arm (114) extending from the pawl axis (116) and having a pawl cam (118) configured to engage a slider cam (119) on the slider assembly (10) in order to pivot the pawl assembly (110) for the pawl arm (112) to engage the slot (20). The track lock assembly (100) further includes a compliant member (160), and a position lock assembly (150) comprising a first lock arm (152) extending from a lock axis (156) and an actuator (170) configured to urge rotation of the first lock arm (152) between a lock locked position and a lock unlocked position, the first lock arm (152) configured to engage and retain the cam arm (114) in a pawl locked position when the first lock arm (152) is in the lock locked position and disengage the cam arm (114) in the lock unlocked position such that the compliant member (160) is able to urge the pawl assembly (110) to a pawl unlocked position.