Change Drum Magnetic Position Sensing Without Contact Errors

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Solution Overview

Problem

Existing gear position detection devices for change drums in vehicles are prone to erroneous detection due to variations in contact state and require a wide range for resistance change, limiting flexibility in design and installation.

Innovation Solution

A rotation position detection device using a magnetic field generator fixed to the change drum and a separate magnetic field detector positioned to detect changes in the magnetic field, allowing for accurate detection of the rotational position without reliance on contact state or wide-range installation constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If electrical contact detection is used to detect gear position, then the detection mechanism is simple, but the potential difference varies due to contact state variations causing erroneous detection

Engineering Contradiction:

Improvedetection mechanism complexityVSAvoidgear position detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces the electrical contact-based mechanical detection system with a magnetic field-based detection system. A magnetic field generator (permanent magnet) is fixed to the change drum, and a magnetic field detector (Hall element) detects the magnetic field changes as the drum rotates. This substitution eliminates contact state variations entirely, as the magnetic field detection occurs without physical contact between the detector and the rotating component, thereby resolving the contradiction between simple mechanism and accurate detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a wide range contact surface is used for resistance change detection, then the detection covers the full rotation range, but the design flexibility and installation flexibility are reduced

Engineering Contradiction:

Improvedetection coverage rangeVSAvoidinstallation flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The magnetic field detection system allows the detector to be positioned at a fixed location while the magnetic field generator rotates, eliminating the need for a wide-range contact surface. The magnetic field naturally extends through space, allowing detection at any point within the field range, thus providing both full rotation range detection and high installation flexibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from a one-dimensional contact surface approach to a three-dimensional magnetic field approach. The magnetic field generator creates a magnetic field that extends in multiple dimensions, allowing the detector to be positioned in various locations (radially, axially, or circumferentially) while still detecting the full rotation range, thereby increasing installation flexibility.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If contact-based detection is used, then the device structure is simple, but the contact state variations cause potential difference variations leading to erroneous detection

Engineering Contradiction:

Improvedetection device structureVSAvoiddetection accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the contact-based electrical detection system with a non-contact magnetic field detection system. The magnetic field generator (permanent magnet) is fixed to the change drum, and the magnetic field detector (Hall element) detects the magnetic field changes as the drum rotates. This substitution eliminates contact state variations entirely, as the magnetic field detection occurs without physical contact between the detector and the rotating component, thereby resolving the contradiction between simple structure and reliable detection.

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 solution minimizes erroneous detection and design constraints by using a magnetic field-based system that accurately detects the rotational position of the change drum, improving detection accuracy and flexibility in device layout.

Implementation Method 1

a magnetic field generator (110) that is fixed to a change drum (60) and that rotates along with the change drum (60) to differentiate an ambient magnetic field

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Implementation Method 2

a magnetic field detector (140) that is formed separately from the magnetic field generator (110) and that is fixed to a position at which a magnetic field changes in response to rotation of the magnetic field generator (110), to detect the magnetic field

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS11293547B2Rotation position detection device for change drum and motorcycle

Publication Date: 2022.04.05 KAWASAKI MOTORS LTD

AI summary

A rotation position detection device includes a change drum, a magnetic field generator, and a magnetic field detector. The magnetic field generator is fixed to the change drum and rotates along with the change drum to differentiate an ambient magnetic field. The magnetic field detector is formed separately from the magnetic field generator and fixed to a position at which a magnetic field changes in response to rotation of the magnetic field generator so as to detect the magnetic field and output a signal that depends on the rotational position of the change drum on the basis of the detection result.