Aircraft Throttle Lever Linkage With Jam-Tolerant RVDT Redundancy

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Solution Overview

Problem

Existing aircraft throttle systems are prone to mechanical failures due to the lack of redundancy and protection against jamming in the mechanical linking systems, which can lead to interference and operational failures in critical engine control systems.

Innovation Solution

A throttle system with a single lever connected to multiple independent mechanical-rotation to electronic-conversion devices, such as RVDTs, and a design that includes shearable fasteners or frangible links to create points of failure, allowing the system to disengage and prevent jamming, ensuring continued operation even if one mechanical linking system fails.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single mechanical linking system is used to connect the throttle lever to the RVDT, then the device complexity is reduced, but the reliability decreases due to lack of redundancy

Engineering Contradiction:

Improvemechanical linking systemVSAvoidengine control system

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The mechanical linking system is divided into multiple independent pathways, each connecting the throttle lever to a separate RVDT. This segmentation ensures that if one linkage fails, other independent linkages remain functional, providing redundancy without significantly increasing overall system complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the mechanical linking system are designed with varying properties - some components are made with shearable fasteners or frangible links that are intentionally weaker to create designed points of failure. This local differentiation allows the system to sacrifice specific components to protect the overall system reliability.

Inventive Principle:

Principle #3Local quality

2Strength

If the mechanical linking system is made rigid and strong, then the strength increases, but the reliability decreases due to potential jamming that affects the entire system

Engineering Contradiction:

Improvemechanical linking systemVSAvoidthrottle lever operation

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The system incorporates designed points of failure using shearable fasteners or frangible links that are positioned to fail before critical jamming occurs. These pre-positioned weak points act as cushions, allowing the system to fail gracefully in a controlled manner rather than experiencing catastrophic jamming that would affect the entire throttle control system.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The potential harm of mechanical failure is converted into a benefit by designing specific components to fail in a controlled manner. When a shearable fastener or frangible link fails, it prevents jamming from propagating through the entire system, allowing the throttle lever to remain operable through alternative independent linkages.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If redundant RVDTs are connected through a common mechanical system, then the reliability improves through redundancy, but the object-generated harmful factors increase due to potential interference and jamming

Engineering Contradiction:

Improveengine control systemVSAvoidmechanical interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

Each RVDT is connected to the throttle lever through its own independent mechanical linkage, completely separate from other RVDT linkages. This segmentation eliminates mechanical interference between redundant components while maintaining reliability through diversity. If one linkage experiences jamming or failure, it cannot affect the operation of other independent linkages.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The throttle lever serves as an intermediary that distributes mechanical input to multiple independent RVDT linkages. Each linkage acts as a separate mediator between the pilot's input and the electronic control system, ensuring that failures in one pathway do not propagate to other pathways.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 ensures continued operation of the throttle lever and engine control by allowing other RVDTs to function independently if one mechanical linking system jams, maintaining engine control and preventing interference, thus enhancing reliability and safety.

Implementation Method 1

RVDTs, as is known in the art, take mechanical rotation, and based on angular displacement, transmit signals so that the extent of displacement can be used by digitally-based electronic systems existing in the aircraft

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11542883B2Throttle system

Publication Date: 2023.01.03 TEXTRON INNOVATIONS INC

AI summary

Disclosed is a throttle quadrant arrangement utilizing a throttle lever mechanically connected to three Rotary Variable Differential Transformers (RVDTs). The signals from the RVDTs are monitored by a process where the processing component. More specifically, RVDT outputs are monitored by the engine control system to determine if they are outside a predetermined range of operability. If an RVDT is not operable, the engine control system establishes a thrust output using the signal from one of the functional two. If only one or none are within the range, the system moves on to a default mode.