Gap Compensation for Magnetostrictive Torque Sensors

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Solution Overview

Problem

Magnetostrictive torque sensors face inaccuracies due to variations in the gap between the sensor and the monitored component, which can be influenced by vibrations and changes in the component's shape, leading to deviations in torque measurements independent of the actual applied torque.

Innovation Solution

A gap-compensated torque sensing system that integrates a proximity sensor with the magnetostrictive torque sensor, allowing for independent measurement of the gap and adjustment of torque readings to account for variations, thereby enhancing measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetostrictive torque sensor is used to measure torque, then torque measurement capability is achieved, but measurement precision deteriorates due to gap variations

Engineering Contradiction:
Improvetorque measurement accuracyVSAvoidmeasurement stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent segments the measurement function into two independent parts: a magnetostrictive sensor for torque measurement and a separate proximity sensor for gap measurement. This segmentation allows each sensor to perform its specific function without interference, enabling independent compensation of gap variations to improve torque measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where the proximity sensor continuously monitors gap variations and this information is used to compensate the torque measurements from the magnetostrictive sensor. The feedback loop corrects measurement errors caused by gap changes, thereby improving measurement precision and reliability.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If gap compensation is implemented using traditional methods, then some accuracy improvement is achieved, but device complexity increases

Engineering Contradiction:
Improvetorque measurement accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The proximity sensor serves multiple functions: it measures gap distance for compensation purposes, and its measurements are universally applicable to correct all torque readings affected by gap variations. This multi-functionality approach improves precision without proportionally increasing complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces complex mechanical gap adjustment mechanisms with electronic sensing and computational compensation. The proximity sensor and processing system substitute for mechanical solutions, achieving precision improvement through electronic means rather than mechanical complexity.

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 system improves the accuracy of torque measurements by isolating gap-related changes from electromagnetic property variations, reducing errors and achieving better control of rotating machine components.

Implementation Method 1

magnetostriction is a property of ferromagnetic materials that characterizes changes in shape (e.g., expansion or contraction) of the material in the presence of a magnetic field

Methodology Applied
Scientific EffectMagnetostriction: Magnetostriction

Implementation Method 2

A magnetostrictive torque sensor can generate magnetic flux that permeates a shaft and it can sense the magnetic flux as it interacts with the shaft

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 3

these changes in distance can cause variations in the magnetic flux sensed by a magnetostrictive torque sensor

Methodology Applied
Scientific EffectMagnetic flux sensing: Magnetic Field

Data Source

PatentEP3444581B1Improved gap compensation for magnetostrictive torque sensors
Publication Date: 2021.07.28 BENTLY NEVADA INC
  • EP3444581B1 patent drawingFigure 1
  • EP3444581B1 patent drawingFigure 2
  • EP3444581B1 patent drawingFigure 3

AI summary

A gap compensated torque sensing system and methods for using the same are provided. The system can include a sensor head in communication with a controller. The sensor head can contain a torque sensor and a proximity sensor coupled to the sensor head. The torque and proximity sensors can each sense magnetic fluxes passing through the target and a gap between the sensor head and the target. The controller can estimate torque applied to the target from magnetic fluxes sensed by the torque sensor. The controller can determine an improved gap measurement that is independent of electromagnetic properties of the target from magnetic fluxes sensed by the torque and proximity sensors. The estimated torque can be modified by the improved gap measurement to compensate for changes in magnetic properties of the target due to variations in the gap. In this manner, the accuracy of the torque measurements can be increased.