Telescopic Actuator Auxiliary Rod Jamming Prevention

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Solution Overview

Problem

Telescopic actuators used in applications like aircraft landing gear face a risk of main rod jamming, which prevents the actuator from functioning and can pose a safety hazard by blocking movement of the mechanical system.

Innovation Solution

A telescopic actuator design that includes an auxiliary rod mounted to slide within the main rod, with controlled retaining means to keep the auxiliary rod retracted until the main rod jams, allowing the auxiliary rod to extend and prevent jamming, ensuring continued movement of the mechanical system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a telescopic actuator with main rod and auxiliary rod is used to increase stroke, then the actuator length is extended, but the risk of main rod jamming increases which blocks mechanical system movement

Engineering Contradiction:

Improveactuator strokeVSAvoidjamming resistance

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The actuator is divided into two independent rod systems: a main rod and an auxiliary rod. The auxiliary rod can operate independently within the main rod, providing segmentated functionality where one segment (auxiliary rod) can compensate for failures in the other segment (main rod), thereby resolving the contradiction between extended stroke and jamming resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the operational parameter of the auxiliary rod from static to dynamic. By introducing controlled retaining means that can transition between locked and unlocked states, the auxiliary rod's position parameter becomes variable, enabling it to remain retracted during normal operation and extend only when the main rod jams, thus improving reliability without compromising the extended stroke capability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If controlled retaining means are added to retain the auxiliary rod in retracted position, then the actuator operates like a conventional actuator, but the device complexity increases

Engineering Contradiction:

Improvejamming protectionVSAvoidactuator structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The controlled retaining means serves multiple functions: it acts as a locking mechanism to hold the auxiliary rod in the retracted position during normal operation, and simultaneously serves as a release mechanism that enables the auxiliary rod to extend when the main rod jams. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving jamming protection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The controlled retaining means acts as an intermediary element between the auxiliary rod and the main rod system. It mediates the interaction by controlling when the auxiliary rod remains constrained and when it is freed to compensate for main rod jamming, adding only the necessary complexity to coordinate between the two rod systems without requiring complete system redesign.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Length of moving object

If the auxiliary rod is used to extend the stroke rather than prevent jamming, then the actuator length increases, but the safety hazard from main rod jamming remains

Engineering Contradiction:

Improveactuator strokeVSAvoidsafety hazard from jamming

Core Design Contradiction:

Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

The system applies preliminary anti-action by pre-positioning the auxiliary rod in a retracted state within the main rod, ready to counteract the harmful effect of jamming. The controlled retaining means pre-establishes the constraint that will prevent the auxiliary rod from interfering with normal operation, while also preparing the mechanism to release and extend the auxiliary rod if jamming occurs, thereby neutralizing the safety hazard before it can manifest.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The invention converts the potential harm of main rod jamming into a beneficial trigger mechanism. When the main rod jams, this harmful condition automatically activates the release of the controlled retaining means, which in turn enables the auxiliary rod to extend and restore system functionality. The harmful jamming event is transformed into the activation signal that benefits the system by engaging the backup mechanism.

Inventive Principle:

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

Data Source

PatentUS7802488B2Telescopic actuator with a main rod and an auxiliary rod, and a method making use thereof

Publication Date: 2010.09.28 SAFRAN LANDING SYSTEMS

AI summary

The invention relates to a telescopic actuator comprising a cylinder in which a main rod is mounted to slide telescopically along a sliding axis between a retracted position and an extended position. The actuator includes an auxiliary rod mounted to slide telescopically in the main rod along said sliding axis between a retracted position and an extended position, the actuator including controlled retaining means for retaining the auxiliary rod in the retracted position inside the main rod.