Rotary Shaft Position Sensing Without Micro-Mechanical Switches

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Solution Overview

Problem

Existing rotary shaft position detection systems, particularly in motorized valves, rely on complex and bulky micro-mechanical switches that are prone to wear and require precise assembly, limiting their use in high-vibration environments and increasing maintenance costs.

Innovation Solution

A rotary position detection assembly using a non-conductive plate with conductive tracks and a conductive slider that rotates with the shaft, providing electrical contacts at predetermined positions to generate output signals based on the shaft's position, eliminating the need for micro-mechanical switches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If micro-mechanical switches are used for position detection, then position detection capability is achieved, but device complexity and bulk increase

Engineering Contradiction:

Improveposition detection capabilityVSAvoidsensor construction complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces micro-mechanical switches with a magnetic field-based detection system using a magnet attached to the shaft and a magnetic sensor on the circuit board. This substitution eliminates the need for complex mechanical switch mechanisms while achieving accurate position detection through magnetic field sensing, directly resolving the contradiction between measurement capability and device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If micro-mechanical switches are used for position detection, then position detection capability is achieved, but reliability decreases due to wear and mechanical stress

Engineering Contradiction:

Improveposition detection capabilityVSAvoidswitch durability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent eliminates mechanical contact components by using a magnetic field-based sensing system. The magnet rotates with the shaft and interacts with the magnetic sensor without physical contact, eliminating wear, friction, and mechanical stress that cause reliability issues in micro-mechanical switches, thereby achieving both position detection capability and high reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If micro-mechanical switches are used for position detection, then position detection capability is achieved, but manufacturing and assembly difficulty increase due to tolerance requirements

Engineering Contradiction:

Improveposition detection capabilityVSAvoidassembly difficulty

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the precision-mechanical micro-switch assembly with a magnetic sensing system where a magnet is attached to the shaft and a magnetic sensor is mounted on the circuit board. This system is much more tolerant of manufacturing variations and assembly tolerances because magnetic field sensing does not require the same precision mechanical clearances and alignments that micro-mechanical switches demand, significantly easing manufacturing and assembly.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If micro-mechanical switches are used for position detection, then position detection capability is achieved, but the valve structure size increases

Engineering Contradiction:

Improveposition detection capabilityVSAvoidvalve structure size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent replaces the bulky mechanical switch assembly with a compact magnetic sensing system. The magnet attached to the shaft and the magnetic sensor on the circuit board occupy minimal space compared to the mechanical switch mechanism, allowing for a more compact overall valve structure while maintaining position detection capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 assembly offers a simple, durable, and cost-effective solution for precise rotary position detection, adaptable to various positions, with reduced mechanical stress and improved reliability in harsh environments.

Implementation Method 1

an electrically conductive member mounted to rotate with the shaft and to make contact with the first and the second track

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS20250317031A1Rotary shaft position detection assembly

Publication Date: 2025.10.09 BE AEROSPACE INC

AI summary

A rotary position detection assembly for detecting the rotary position of a rotating shaft, the assembly comprising: a non-conductive plate mounted around the rotating shaft, and relative to which the shaft rotates, in use; the plate having formed thereon a first electrically conductive track forming a closed loop around the shaft, and a second track forming a closed loop around the rotating shaft and having electrically conductive points at predetermined positions around the second track separated by non-conductive portions; an electrically conductive member mounted to rotate with the shaft and to make contact with the first and the second track; and one or more output members to provide an output signal indicative of the rotary position of the shaft based on the position of the electrically conductive member relative to the electrically conductive points of the second track and its electrically conductive contact therewith.