Angular Position Sensor with Segmented Air Gaps and Hard Magnet
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Solution Overview
Problem
Existing angular position sensors face challenges in achieving a wide linearity range and cost-effective manufacturing due to the complexity and processing difficulties of ring magnets used in prior designs.
Innovation Solution
The design incorporates a rotor core and stator core with strategically placed air gaps and hard magnets, optimizing the size and placement of these components to enhance linearity and reduce production costs by simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radially magnetized ring magnet is used to achieve a wide linearity range, then the linearity range is improved, but the ring magnet size and raw material cost increase
Solution Approach 1:
The patent divides the magnetic field generation into two parts: a permanent magnet providing bias flux and a controllable electromagnetic coil providing adjustable flux. This segmentation allows achieving wide linearity range without increasing permanent magnet size, as the coil compensates for non-linearity through controlled current adjustment.
Solution Approach 2:
The patent changes the operating parameters by introducing a controllable electromagnetic coil that adjusts magnetic flux density through variable current. This allows dynamic parameter adjustment to maintain linearity across wide rotation angles without proportionally increasing permanent magnet dimensions.
2Measurement precision
If a radially magnetized ring magnet is used to achieve a wide linearity range, then the linearity range is improved, but the processing difficulty and production cost increase
Solution Approach 1:
The patent segments the magnetic system into a simple permanent magnet structure and a controllable coil assembly. This avoids the need for complex radially magnetized ring magnets, as the coil provides the necessary flux adjustment capability through standard winding techniques rather than complex magnetization patterns.
Solution Approach 2:
The patent replaces the mechanically complex radially magnetized ring magnet with a combination of simple permanent magnet and electromagnetic coil. The coil's electrical control substitutes for the complex mechanical magnetization arrangement, simplifying manufacturing while achieving the same functional outcome.
3Measurement precision
If the first air gap width to rotor core diameter ratio is increased to improve linearity, then the linearity is improved, but the magnetic flux density decreases
Solution Approach 1:
The patent compensates for the decrease in magnetic flux density caused by increased air gap ratio by introducing a controllable electromagnetic coil. The coil generates additional magnetic flux to maintain adequate flux density levels while the larger air gap preserves linearity across wide rotation angles.
Solution Approach 2:
The patent creates a composite magnetic circuit combining permanent magnet material and electromagnetic coil windings. This composite approach allows the system to benefit from both the stable bias flux of the permanent magnet and the adjustable flux of the coil, simultaneously achieving linearity and adequate flux density.
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
This configuration achieves good linearity over a wider range while reducing production costs and complexity, offering improved flexibility and performance compared to traditional ring magnet-based sensors.
Implementation Method 1
a second air gap with a hard magnet therein is provided inside the rotor core
Implementation Method 2
the hard magnet and the rotor core for forming a magnetic circuit together with the stator core
Implementation Method 3
the magnetic flux density where the magnetic flux sensing element is located be linear with the rotation angle
Implementation Method 4
a magnetic induction element to detect the magnetic field variation, which is then converted into the electrical signal output
Data Source
AI summary
The present invention discloses an angular position sensor, which includes a rotor core as well as a stator core coaxially around this rotor core. Between the rotor core and the stator core is a first air gap, and inside the rotor core a second air gap, which is provided inside with a hard magnet. The stator core has a third air gap inside, which is provided inside with a magnetic flux sensing element. It is obvious that the present invention, by substituting the combination of the hard magnet and the rotor core for the design of ring magnet in the prior art, obtains the good linearity within a wider range.