Contactless Torque Measurement Using Inclined Magnetic Flux
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing torque and force measurement technologies require permanent attachment or modification of the test subject, are sensitive to magnetic fields, and have limitations in measuring torque and force on rounded shafts without flattening the surface or requiring degaussing.
Innovation Solution
A contactless torque and force measurement system using a magnetic field generator with a ferromagnetic flux concentrator and a sensing arrangement inclined 90° to the magnetic field generating direction, allowing for the measurement of torque and force impacts on a shaft or other corpus without the need for surface flattening or pre-processing, using AC fields and a sensing coil to detect field modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface acoustic wave technology is used for torque sensing, then torque measurement capability is improved, but the shaft surface must be flattened which increases device complexity and preparation requirements
Solution Approach 1:
The patent replaces mechanical contact methods (strain gages requiring surface attachment, surface acoustic waves requiring flattened surfaces) with a contactless magnetic field-based measurement system. The magnetic field generator and sensor arrangements measure torque through magnetic flux modifications without physical contact or surface modification, thereby eliminating the need for surface flattening while maintaining measurement capability.
2Measurement precision
If permanent shaft magnetization method is used, then torque measurement is enabled, but the shaft must be degaussed and magnetically tuned which increases loss of time and processing steps
Solution Approach 1:
The patent substitutes permanent magnetization methods with a contactless AC magnetic field generation approach. The magnetic field generator produces an alternating magnetic field that induces eddy currents in the shaft, creating magnetic flux modifications detectable by the sensor arrangement. This eliminates the time-consuming degaussing and magnetic tuning steps while enabling torque measurement through the inclination-based sensing mechanism.
Solution Approach 2:
The patent employs periodic AC magnetic field generation at frequencies between 50 Hz and 10 kHz. The alternating magnetic field induces periodic eddy currents in the shaft, creating time-varying magnetic flux that the sensor arrangement detects. This periodic action enables torque measurement without permanent magnetization, eliminating the need for degaussing and magnetic tuning procedures.
3Measurement precision
If magnetic field generator and sensor are arranged orthogonally (90° inclination), then signal-to-noise ratio is improved by eliminating background field interference, but the device complexity increases
Solution Approach 1:
The patent employs asymmetric orthogonal arrangement where the magnetic field generator and sensor arrangements are positioned at 90° inclination to each other. This asymmetric configuration causes the generator's magnetic field to be perpendicular to the sensor's sensitive direction during idle conditions, eliminating background field interference. When torque is applied, the shaft's magnetic properties modify the flux path, creating a detectable signal component along the sensor's sensitive axis, thereby achieving high signal-to-noise ratio.
4Ease of operation
If contactless measurement method is used, then ease of operation is improved by eliminating surface preparation, but measurement precision may be affected by air gap and field strength
Solution Approach 1:
The patent employs dynamic AC magnetic field generation and sensing, where both the magnetic field generator and sensor arrangements operate with time-varying fields. The AC field induces eddy currents in the shaft, creating dynamic magnetic flux modifications that are detected by the sensor arrangement. This dynamic approach compensates for air gap effects and maintains measurement precision while enabling contactless operation.
Solution Approach 2:
The patent utilizes parameter changes in the magnetic field frequency (50 Hz to 10 kHz) and amplitude to optimize measurement precision. By varying the AC field frequency and strength, the system can penetrate different air gaps and shaft materials effectively, maintaining measurement precision while preserving the contactless operation advantage.
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 provides high signal-to-noise ratio and low noise measurements, enabling efficient and non-invasive torque and force sensing on various shapes and sizes of shafts, including rotating and moving objects, without interference from static magnetic fields.
Implementation Method 1
a magnetic field generator arrangement (10) having a main magnetic field generating direction (11) for providing a magnetic field in the shaft (100) to be measured
Implementation Method 2
the magnetic field generator arrangement (10) comprises a ferromagnetic flux concentrator (12) having two pole shoes (14, 16) to be positioned facing the shaft (100) to be measured
Implementation Method 3
a magnetic field sensor arrangement (20) having a main magnetic field sensing direction (21) for sensing a magnetic field of a magnetic field provided by the magnetic field generator arrangement (10) upon torque and/or force impact on the shaft (100) to be measured
Implementation Method 4
using AC fields and a sensing coil to detect field modifications
Data Source
Figure 1~2
Figure 3~7
Figure 8~9
AI summary
Torque and force measurement system for measuring toque and/or force impact on a shaft 100 comprising a magnetic field generator arrangement 10 having a main magnetic field generating direction 11 for providing a magnetic field in the shaft to be measured, a magnetic field sensor arrangement 20 having a main magnetic field sensing direction 21 for sensing a magnetic field of a magnetic field provided by the magnetic field generator arrangement upon torque and/or force impact on the shaft to be measured, wherein the main magnetic field generating direction and the main magnetic field sensing direction are inclined β to each other, wherein the magnetic field generator arrangement comprises a ferromagnetic flux concentrator 12 having two pole shoes 14, 16 to be positioned facing the shaft to be measured, wherein the magnetic field sensing arrangement is arranged between the pole shoes adjacent to the shaft to be measured.