Inductive Door Position Sensor Using Nested Coils
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Solution Overview
Problem
Conventional door position sensors using potentiometers or optical encoders face issues such as short lifespan due to mechanical wear and power dependency, leading to recalibration needs after power failures.
Innovation Solution
A door operator system incorporating an inductive sensor with nested coils and a controller that provides a varying power signal to inductively link with a rotatable arm, allowing for precise determination of the arm's rotational position without mechanical wear and power loss concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a potentiometer is used for door position sensing, then the system can detect door position, but the mechanical wear between the wiper and resistive material causes a relatively short life span
Solution Approach 1:
The patent replaces the mechanical potentiometer system with an inductive sensor system that uses electromagnetic fields instead of mechanical contact. The inductive sensor includes a coil that generates a magnetic field, and a target element with a ferromagnetic layer that interacts with this field. This substitution eliminates the wiper and resistive material contact, thereby eliminating mechanical wear and significantly extending sensor lifespan.
Solution Approach 2:
The patent introduces a ferromagnetic target element as an intermediary between the inductive sensor and the door position measurement system. This target element, with its ferromagnetic layer, mediates the interaction by concentrating and directing the magnetic field lines, enabling precise position detection without direct mechanical contact between the sensor and moving parts.
2Reliability
If an optical encoder is used for door position sensing, then the system can detect door position, but a power loss causes the controller to reset the internal counter requiring recalibration
Solution Approach 1:
The inductive sensor system is designed to be self-calibrating and maintains continuous position information without requiring external power or recalibration. The magnetic field and ferromagnetic target element system naturally maintains its state, and the controller can continuously track door position even through power interruptions without resetting counters or requiring recalibration sequences.
3Ease of operation
If a potentiometer or optical encoder is used, then door position can be detected, but recalibration is required after power failure events
Solution Approach 1:
The inductive sensor system automatically maintains accurate position information through its magnetic field mechanism, eliminating the need for manual or automated recalibration procedures after power failures. The system serves itself by continuously maintaining position data integrity without requiring operator intervention or time-consuming recalibration sequences.
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 inductive sensor system offers a durable and power-independent solution for accurately tracking door positions, reducing the need for recalibration and enhancing reliability.
Implementation Method 1
The inductive sensor is configured to inductively link the inductor to the arm in response to the varying power signal
Data Source
AI summary
One embodiment relates to a door operator including an operator body including a rotatable pinion, an arm connected to the pinion, an inductive sensor mounted adjacent the arm, and a controller in communication with the inductive sensor. The inductive sensor includes an inductor comprising a plurality of nested coils, and each of the coils is curved about the pinion. The controller is configured to provide the inductive sensor with a varying power signal, and the inductive sensor is configured to inductively link the inductor to the arm in response to the varying power signal. The inductive sensor has a characteristic which varies in response to the rotational position of the arm when the inductor is inductively linked with the arm. The controller is further configured receive information relating to the characteristic, and to determine the rotational position of the arm based upon the received information.