Torque Sensor Injection Molded Magnets Cost Reduction
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Solution Overview
Problem
Conventional small diameter torque sensors rely on expensive sintered neodymium magnets, leading to high manufacturing costs and signal noise, while struggling to achieve high magnetic field and rotational accuracy without these magnets.
Innovation Solution
A non-contacting torque sensor design featuring a magnetic flux generating rotor with injection molded N and S pole magnets, disposed axially between stators, and a magnetic flux detecting probe, which detects variations in magnetic flux to measure relative twist between the rotor and stators, reducing costs and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sintered neodymium magnets are used to create the magnetic field, then magnetic field strength and rotational accuracy are improved, but manufacturing cost and signal noise increase significantly
Solution Approach 1:
The patent replaces expensive sintered neodymium magnets with injection-molded flexible magnet material that is bonded to the rotor. This substitution uses a cheaper material (flexible magnet material) that can be manufactured at lower cost through injection molding, while still providing sufficient magnetic field strength for the torque sensor application.
Solution Approach 2:
The patent changes the magnetic material parameters from high-strength sintered neodymium to flexible magnet material with different magnetic properties. By adjusting the magnetization direction (radial vs. axial) and using the flexibility of the molded material to conform to the rotor surface, the patent achieves the required magnetic field characteristics without the cost of premium magnets.
2Illumination intensity
If sintered neodymium magnets are used to create the magnetic field, then magnetic field strength is improved, but signal noise increases significantly
Solution Approach 1:
The patent replaces expensive sintered neodymium magnets with injection-molded flexible magnet material that is bonded to the rotor. This substitution uses a cheaper material (flexible magnet material) that can be manufactured at lower cost through injection molding, while still providing sufficient magnetic field strength for the torque sensor application.
3Illumination intensity
If traditional radially-oriented sintered magnets are used, then magnetic field is generated, but cost and manufacturing complexity increase
Solution Approach 1:
The patent replaces the traditional mechanical process of attaching radially-oriented sintered magnets with injection molding technology. The flexible magnet material is injected directly into molds that form the magnet segments and bond them to the rotor in a single integrated process, eliminating complex assembly steps and reducing manufacturing complexity.
Solution Approach 2:
The patent changes the magnetic material parameters from high-strength sintered neodymium to flexible magnet material with different magnetic properties. By adjusting the magnetization direction (radial vs. axial) and using the flexibility of the molded material to conform to the rotor surface, the patent achieves the required magnetic field characteristics without the cost of premium magnets.
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 design achieves high magnetic field and rotational accuracy with reduced manufacturing costs and minimal signal noise, providing a robust and cost-effective solution comparable to traditional magnet-based sensors.
Implementation Method 1
plurality of N pole magnets 112 and S pole magnets 114 alternatingly disposed proximate the radially outboard surface 110
Implementation Method 2
The magnetic flux detecting probe 108 is disposed at a distance from the radially outboard surface and configured for detecting variations in magnetic flux produced by the magnetic flux generating rotor
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A non-contacting torque sensor comprises a magnetic flux generating rotor and a magnetic flux detecting probe. The magnetic flux generating rotor is disposed axially between a first stator and a second stator and has a radially outboard surface and plurality of N pole magnets and S pole magnets alternatingly disposed proximate the radially outboard surface. Each stator has a plurality of stator teeth, with each one of said plurality of stator teeth corresponding to a unique one of said plurality of N pole magnets and S pole magnets. The magnetic flux detecting probe is disposed at a distance from the radially outboard surface and configured for detecting variations in magnetic flux produced by the magnetic flux generating rotor to detect a change of a relative twist between the magnetic flux generating rotor and the first stator and second stator. The N pole magnets and S pole magnets are injection molded.