Tachometer Shaft Connection for Aircraft Wheel Signal Noise Reduction

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Solution Overview

Problem

Existing methods for connecting a tachometer shaft to an aircraft wheel result in noisy signal readings at low speeds, making it difficult to effectively regulate braking.

Innovation Solution

A connection method is introduced where the tachometer shaft end is equipped with a supporting member that engages an elastic member within a housing, reducing noise by compensating for any rotational play between the shaft and housing, utilizing a fluted input and a rotating sleeve with a torsion spring to maintain alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a tachometer shaft is directly engaged in a housing with a non-circular section drive, then the connection is simple and direct, but the signal becomes noisy at low speeds due to rotational play

Engineering Contradiction:
Improveconnection structureVSAvoidtachometer signal quality
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

A sleeve is introduced as an intermediary component between the tachometer shaft and the housing. The sleeve contains a support member that engages with the shaft end, while the housing contains an elastic member that engages with the sleeve. This intermediary structure eliminates direct engagement issues and reduces rotational play, thereby reducing signal noise at low speeds while maintaining connection simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The connection structure is divided into three separate components: the tachometer shaft, the sleeve with support member, and the housing with elastic member. This segmentation allows each component to be optimized independently - the shaft for rotational drive, the sleeve for precise positioning, and the housing for elastic engagement - resolving the contradiction between simple connection and precise signal measurement.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If filtering is applied to the tachometer signal, then some noise reduction is achieved, but important information is masked when noise is severe

Engineering Contradiction:
Improvesignal noiseVSAvoidusable signal information
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

Instead of filtering the signal after it is generated, the invention takes preliminary action by eliminating the source of noise - rotational play - through the support member and elastic member engagement. By preventing the mechanical play that causes noise before the signal is generated, the original signal information is preserved without needing aggressive filtering that would mask useful information.

Inventive Principle:
Principle #10Preliminary 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 significantly reduces noise in the tachometer signal at low speeds, allowing for accurate braking regulation by ensuring a precise and stable connection between the tachometer shaft and the wheel.

Implementation Method 1

an elastic member (18) to make up any rotating game between the end of the shaft and the housing

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the elastic member comprises a twisting spring acting on the sleeve to remember to a position

Methodology Applied
Scientific EffectTorsion spring: Torsion Spring

Data Source

PatentEP3309066B1Method for linking the shaft of a tachometer and an aircraft wheel
Publication Date: 2021.12.01 SAFRAN LANDING SYSTEMS
  • EP3309066B1 patent drawingFigure 1
  • EP3309066B1 patent drawingFigure 2~3
  • EP3309066B1 patent drawingFigure 4a~4b

AI summary

The invention relates to a method for connecting one end (9) of a tachometer shaft (8) (7) disposed in a landing gear axle (1) to a wheel (2) rotatably mounted on said axle. The method comprises the step of equipping the wheel with a housing (14) adapted to receive the end of the tachometer shaft and drive the shaft in rotation with the wheel. The housing includes a support member (17) projecting inside the housing to be pushed by the end of the shaft against an elastic member (18) to compensate for any play between the end of the shaft and the housing. The invention also relates to a socket for this connection.