Torque and Rotation Sensing With Ferrite-Coupled Wide Air Gaps
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Solution Overview
Problem
Existing torque and angle of rotation detection systems, such as KiTorq, face challenges with narrow radial air gaps, susceptibility to external magnetic fields, high manufacturing costs, and difficulty in mounting the stator unit close to the rotor unit due to space constraints.
Innovation Solution
The system employs dipole magnets with high remanence and ferrite elements in the secondary coil, allowing for a wider radial air gap with increased tolerance, improved inductive coupling efficiency, and easier stator unit mounting, using ferrite elements secured in blind holes and a rotor cover to protect components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the radial air gap between stator unit and rotor unit is reduced to achieve accurate magnetic field measurements, then measurement precision is improved, but device complexity and manufacturing cost increase due to tight tolerance requirements
Solution Approach 1:
The patent changes the magnetic properties of the rotor unit by introducing ferrite elements with high magnetic permeability. This parameter change allows the system to tolerate larger radial air gaps while maintaining measurement precision, as the enhanced magnetic coupling compensates for the increased distance between stator and rotor components.
Solution Approach 2:
Ferrite elements are introduced as intermediary magnetic components on the rotor unit. These elements act as magnetic mediators that strengthen the magnetic field coupling between the stator magnets and rotor sensors, enabling accurate measurements even with larger air gaps and relaxed tolerance requirements.
2Ease of manufacture
If dipole magnets with low remanence are used, then manufacturing cost is reduced, but reliability deteriorates due to susceptibility to external magnetic fields
Solution Approach 1:
The patent changes the magnetic parameter of the system by using ferrite elements with high magnetic permeability and optimized remanence characteristics. This parameter optimization allows the use of cost-effective magnet materials while achieving reliable operation resistant to external magnetic fields through enhanced magnetic field stability.
3Ease of manufacture
If iron powder/resin mixture is used in secondary coil, then ease of manufacture is improved, but inductive coupling efficiency deteriorates due to air inclusions
Solution Approach 1:
The patent uses a composite material approach by combining ferrite particles or elements with resin binder to create a magnetic composite for the secondary coil. This composite material provides both ease of application (similar to iron powder/resin) and high magnetic permeability (unlike iron powder), eliminating the air inclusion problem while maintaining manufacturing simplicity.
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 achieves accurate torque and angle of rotation measurements with reduced interference from external fields, lower manufacturing costs, and simplified installation, enabling a broader air gap and axial offset tolerance.
Implementation Method 1
When an electrical voltage is applied to the measuring grid, the measuring grid exhibits an electrical resistance. The electrical resistance changes upon expansion or compression of the measuring grid, which change in electrical resistance generates measurement signals in the bridge circuit.
Implementation Method 2
The primary and secondary coils are inductively coupled to one another. A primary electrical voltage in the primary coil generates a secondary electrical voltage in the secondary coil. Inductive coupling of the primary and secondary coils occurs in a contactless manner
Implementation Method 3
The rotor unit comprises a plurality of dipole magnets which are spaced apart from each other. The stator unit comprises a magnetic field sensor that measures the magnetic fields of the dipole magnets during rotation of the rotor unit.
Data Source
AI summary
A torque and angle of rotation detection system is rotatable about an axis of rotation and includes a stator unit separated from a rotor unit by an air gap disposed radially with respect to the axis of rotation. The rotor unit includes strain gauges, dipole magnets and a secondary coil with ferrite elements. The stator unit includes a magnetic field sensor and a primary coil wherein a primary electrical voltage in the primary coil generates a secondary electrical voltage in the secondary coil.