Magnetoelastic Torque Sensor Noise Reduction
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Solution Overview
Problem
Existing torque sensing devices suffer from rotation noise due to physical irregularities and variations in magnetic field strength and direction, which affect the accuracy of torque measurement.
Innovation Solution
A method and system for magnetizing a torque transducer that adjusts the magnetization field direction to eliminate rotation noise by using a computer-controlled system to measure and adjust the magnetization of a disk or shaft, accounting for irregularities and physical variations, thereby forming magnetically conditioned regions that produce minimal rotation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ring of magnetoelastically active material is disposed around the shaft to sense torque, then torque sensing capability is improved, but rotation noise is generated due to physical irregularities and magnetic field variations
Solution Approach 1:
The patent applies local quality by creating magnetically conditioned regions with specific circumferential magnetic polarization in selected areas of the shaft or disk. These localized regions with controlled magnetic properties (different from the surrounding material) produce consistent magnetic fields that cancel out rotation noise while maintaining torque sensing capability in the magnetoelastically active regions.
2Measurement precision
If magnetically conditioned regions are created to reduce rotation noise, then measurement accuracy is improved, but device complexity increases due to additional magnetization steps
Solution Approach 1:
The patent applies preliminary action by performing magnetization of the shaft or disk in a specific sequence during manufacturing. The magnetically conditioned regions are established in advance with circumferential polarization before the torque sensing operation begins. This preliminary magnetization step ensures that when the device operates, the magnetic fields from these pre-conditioned regions automatically compensate for rotation noise without requiring real-time adjustments or complex control systems.
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 effectively reduces rotation noise, enhancing the accuracy of torque measurement and allowing for precise determination of angular speed and orientation by ensuring consistent magnetization across different angular positions.
Implementation Method 1
the magnetoelastically active region includes one or more magnetically conditioned regions that are magnetically polarized in a circumferential direction and possess sufficient magnetic anisotropy to return the magnetization in the region, following the application of torque to the shaft, to the circumferential direction when the applied torque is reduced to zero. When a torque is applied to the shaft, the circumferential magnetic orientations of the magnetically conditioned regions reorient such that they exhibit helical magnetic orientations having both circumferential and axial components.
Implementation Method 2
Magnetic field sensors mounted proximate to the magnetically conditioned regions, without contacting the regions, are configured to sense only the axial components of magnetic fields produced by the regions.
Data Source
AI summary
A system and method for creating one or more magnetically conditioned regions on a rotatable shaft or disk-shaped torque sensing element, wherein rotation noise produced by the element due to magnetic field variations is substantially negated, and a system and method for creating one or more magnetically conditioned regions on a rotatable shaft or disk-shaped element to allow the element to function as part of a rotational speed or rotational position sensing device.