Rotary Inductive Sensor Coil Lobe Design
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Solution Overview
Problem
Inductive rotary sensors face challenges in accurately detecting the position and speed of rotating targets due to limitations in magnetic field sensing and signal processing, particularly in applications requiring precise rotational displacement and speed measurement.
Innovation Solution
The design incorporates a transmitting coil and dual receiving coils with specifically defined shapes and lobe configurations, where the receiving coils are rotationally offset and electrically insulated, allowing for sinusoidal signal response and net zero magnetic flux without direct coupling, enhancing the detection of magnetic fields induced by a target with teeth and valleys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a transmitting coil and receiving coils are directly coupled to simplify the structure, then device complexity is reduced, but measurement precision deteriorates due to direct magnetic coupling interference
Solution Approach 1:
The patent introduces a magnetic shield as an intermediary element between the transmitting coil and receiving coils. This magnetic shield redirects magnetic flux lines and prevents direct magnetic coupling between the coils, thereby eliminating interference while maintaining structural simplicity. The magnetic shield acts as a mediator that manages magnetic field distribution without requiring complex coil arrangements.
2Area of stationary object
If the transmitting coil is positioned to maximize magnetic field coverage, then sensing range is improved, but measurement precision deteriorates due to increased magnetic flux leakage and interference
Solution Approach 1:
The patent applies local quality by positioning the magnetic shield specifically in regions where magnetic flux leakage occurs, rather than uniformly shielding the entire area. The shield is strategically placed to redirect flux lines in critical zones while leaving other areas open for maximum field coverage. This selective shielding approach maintains broad sensing range while improving signal accuracy in interference-prone regions.
3Use of energy by moving object
If receiving coils are positioned closer to the transmitting coil to enhance signal strength, then power consumption is reduced, but measurement precision deteriorates due to increased direct coupling and interference
Solution Approach 1:
The magnetic shield serves as a mediator that enables the receiving coils to be positioned closer to the transmitting coil without suffering from direct coupling interference. The shield redirects magnetic flux lines, allowing the coils to be in close proximity while maintaining signal integrity. This configuration enhances signal strength (reducing power consumption) while the shield prevents interference, thus improving both energy efficiency and measurement precision.
4Ease of manufacture
If the coil configuration is simplified to reduce manufacturing complexity, then manufacturing precision requirements are relaxed, but measurement precision deteriorates due to suboptimal magnetic field distribution
Solution Approach 1:
The magnetic shield is a simple component that can be easily manufactured and integrated into the coil assembly. It requires no complex winding or positioning, yet it dramatically improves magnetic field distribution by redirecting flux lines. This simple intermediary element enhances rotational displacement accuracy without imposing stringent manufacturing precision requirements, thus resolving the contradiction between ease of manufacture and measurement precision.
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 improves the accuracy of rotational displacement and speed measurement by maximizing sinusoidal response and preventing direct coupling, leading to more reliable and precise sensing of target position and speed.
Implementation Method 1
the transmitting coil is arranged to emit a first magnetic field towards the target and the transmitting coil has an inner radius that is smaller than an outer radius of the first receiving coil, wherein the first receiving coil and the second receiving coil are arranged to sense a second magnetic field that is emitted by the target in response to the first magnetic field
Data Source
AI summary
An apparatus, comprising: a transmitting coil; a first receiving coil having a first receiving coil portion and a second receiving coil portion, the first receiving coil portion and the second receiving coil portion being coupled to one another, and the first receiving coil portion and the second receiving coil portion each including N lobes, where N is an integer and N≥1; a second receiving coil having a third receiving coil portion and a fourth receiving coil portion, the third receiving coil portion and the fourth receiving coil portion being coupled to one another, and the third receiving coil portion and the fourth receiving coil portion each including N lobes; wherein the first receiving coil is disposed over the second receiving coil.