Magnetic Resonance Steering Position Sensor for Forklifts

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Solution Overview

Problem

Conventional position measuring devices for industrial truck steering systems face issues with wear, sealing, and accuracy in damp environments, and provide only discrete measurements, leading to potential errors and increased tire wear.

Innovation Solution

A non-contact, analog position measuring system using magnetic resonance sensors to detect the position of a magnet on a tie rod, generating continuous signals that allow for precise steering angle calculation and error detection, with sensors housed in protective housings for reliability in harsh conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional potentiometers are used for position sensing, then the device can measure position, but the wiper and resistance track experience wear and require sealing in damp environments

Engineering Contradiction:
Improveposition sensing reliabilityVSAvoidwear and sealing requirements
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical contact-based potentiometer system with a magnetic field-based sensing system. A magnet is attached to the moving component (tie rod), and magnetic sensors (such as Hall sensors or magnetoresistive sensors) are mounted on the stationary part. The magnet's position is detected through changes in the magnetic field, eliminating the need for physical contact between moving and stationary components, thus removing wear and sealing requirements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the moving magnet and the stationary magnetic sensors. This magnetic field mediator allows position information to be transmitted without direct mechanical contact, solving the wear and sealing problems while maintaining continuous analog position measurement capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If discrete proximity switching elements are used for position measurement, then the device can detect position, but only discrete values are obtained leading to imprecise measurements

Engineering Contradiction:
Improvesensor arrangement simplicityVSAvoidsteering angle measurement precision
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent replaces discrete proximity switching elements with continuous magnetic field sensors. Instead of using spaced-apart switching elements that provide stepped position data, the invention uses magnetic sensors that detect the magnet's position continuously through magnetic field strength variations, providing precise analog position measurements while maintaining ease of manufacture.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If a single magnetic sensor is used for position detection, then the device structure is simple, but no error detection capability is provided

Engineering Contradiction:
Improvesensor system complexityVSAvoiderror detection capability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the single sensor function into multiple independent magnetic sensors positioned at different locations. By segmenting the measurement function across multiple sensors, the system can compare readings from different sensors to detect errors, malfunctions, or inconsistencies, thereby providing error detection capability while maintaining relatively simple device structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where the controller receives signals from multiple magnetic sensors and compares the measured position with expected values or with readings from other sensors. This feedback loop enables real-time error detection and can trigger warnings or corrective actions, enhancing system reliability without significantly increasing complexity.

Inventive Principle:
Principle #23Feedback

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

Ensures accurate and reliable steering control, detects malfunctions, prevents accidents, and reduces tire wear by providing continuous, accurate measurements and monitoring capabilities, even in damp or dirty environments.

Implementation Method 1

two magnetic resonance sensors which generate continuous, opposing signals depending on the position of a position sensor magnet

Methodology Applied
Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentEP2100798B1Industrial truck, in particular forklift
Publication Date: 2011.05.25 JUNGHEINRICH AG
  • EP2100798B1 patent drawingFigure 1

AI summary

The truck has a target value sensor (10) connected with a steering wheel (1), and a steering device (40) effectively connected with a steering link (42). Magnetic resonance sensors (50, 52) detect a position of a position generator magnet (44). The magnet and the sensors are moved relative to each other during steering movement of the steering device. A steering controller (20) evaluates signals received from the target value sensor and the resonance sensors for detecting an error function of one of the resonance sensors, and regulates a vehicle steering angle about a target steering angle.