Multi-turn Position Sensor with Threaded Shaft and Hall Effect Detection

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Solution Overview

Problem

Existing position sensors, such as potentiometers, face issues with physical wear and signal drift, leading to errors and potential device failure, especially when detecting multi-turn rotational movements.

Innovation Solution

A rotary position sensor design incorporating a rotatable shaft, threaded members, a magnet, and magnetic flux detection devices, with a redundancy circuit system using Hall devices to detect magnetic fields and reduce errors through majority voting, allowing for accurate multi-turn position sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contact-type sensors (potentiometers) are used to detect position, then position sensing is achieved, but physical wear occurs leading to signal drift and device failure

Engineering Contradiction:

Improvesensor reliabilityVSAvoidsignal accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical contact-based potentiometer system with a magnetic field-based sensing system. A magnet attached to the rotating shaft interacts with a stationary magnetic flux detection device (such as a Hall effect sensor or magnetometer) to generate position signals without physical contact, thereby eliminating wear and signal drift while maintaining position sensing capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the rotating shaft and the detection system. The magnet on the shaft creates a magnetic field that serves as the mediator to transfer rotational position information to the stationary detection device, enabling non-contact signal transmission and eliminating direct mechanical interaction

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If magnetic velocity sensors are used for non-contact detection, then wear is eliminated, but multi-turn position detection capability is insufficient

Engineering Contradiction:

Improvesensor reliabilityVSAvoidmulti-turn position detection

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the position detection function into two independent components: a magnetic flux detection device that provides continuous non-contact position sensing and a separate counting mechanism that tracks the number of revolutions. This segmentation allows each component to specialize in its strength, with the magnetic sensor ensuring reliability and the counter enabling multi-turn measurement

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges the output signals from multiple magnetic flux detection devices and combines them with revolution count data from the threaded member mechanism. This integration creates a composite position measurement system that leverages both the continuous sensing capability of the magnetic devices and the discrete counting capability to achieve accurate multi-turn position detection

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If threaded members are used to convert rotation to linear motion, then multi-turn detection is enabled, but device complexity increases

Engineering Contradiction:

Improvemulti-turn position detectionVSAvoidsensor structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent designs the threaded member assembly to serve multiple functions simultaneously: it converts rotational motion to linear displacement for position measurement, provides a mechanical reference for the magnetic flux detection devices, and enables the counting mechanism for revolution tracking. This multi-functionality reduces the need for separate dedicated components for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables reliable detection of multiple turns of a rotatable shaft, such as a steering wheel, with reduced hysteresis and error detection, ensuring stable and accurate electrical signals over extended rotations.

Implementation Method 1

The at least one magnetic flux detection device is positioned to detect a magnetic field from the at least one magnet

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

at least one magnetic flux detection device... to detect a magnetic field

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS7443160B2Position sensor

Publication Date: 2008.10.28 WOLF RONALD J

AI summary

A position sensor including a rotatable shaft, a first threaded member, a second threaded member, at least one magnet, and at least one magnetic flux detection device. The first threaded member is connected to the rotatable shaft. The second threaded member is threadably engaged with the first threaded member. The at least one magnet is connected to the second threaded member. The at least one magnetic flux detection device is positioned to detect a magnetic field from the at least one magnet.