Elevator Car Position Sensor Phase Detection Shielding
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Solution Overview
Problem
Existing elevator car position detection devices are prone to erroneous detection due to voltage generation from disturbance electromagnetic waves, which can prevent normal detection of the presence or absence of a plate.
Innovation Solution
An elevator car position detection sensor system comprising a first coil to output an excitation magnetic field, a second coil on the opposite side, a shield wall to shield the plate's end portion, and a determination circuit to determine the phase of the alternating-current voltage corresponding to the excitation magnetic field frequency, allowing accurate detection of the plate's presence or absence based on phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coil-based detection system is used to detect plate presence, then detection capability is achieved, but disturbance electromagnetic waves generate voltage across the coil causing erroneous detection
Solution Approach 1:
The patent introduces a shield wall as an intermediary element positioned between the detection coil and the plate. This shield wall selectively blocks disturbance electromagnetic waves while allowing the detection system to function, thereby mediating the harmful interference without eliminating the detection capability
Solution Approach 2:
The patent extracts and separates the harmful disturbance electromagnetic waves from the useful detection signal by using a shield wall. This allows the detection coil to respond only to the intended plate presence signal while ignoring the extracted interference component
2Reliability
If phase detection method is implemented, then erroneous detection is suppressed, but device complexity increases due to additional determination circuit
Solution Approach 1:
The patent changes the detection parameter from simple voltage presence to phase angle measurement. By detecting the phase of the alternating current voltage across the coil relative to a reference, the system can distinguish between true plate presence signals and disturbance waves, improving reliability through parameter transformation
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 effectively suppresses erroneous detection by maintaining a consistent amplitude and phase difference in the voltage across the second coil, even in the presence of disturbance electromagnetic waves, ensuring reliable detection of the plate's presence or absence.
Implementation Method 1
a first coil provided to one of an elevator car and a hoistway and configured to output an excitation magnetic field to a plate provided to the other of the elevator car and the hoistway
Implementation Method 2
a second coil provided on an opposite side of the first coil relative to the plate... an alternating-current voltage generated across the second coil
Data Source
AI summary
To provide an elevator car position detection sensor capable of suppressing erroneous detection of presence or absence of a plate. The elevator car position detection sensor includes a first coil provided to one of an elevator car and a hoistway and configured to output an excitation magnetic field to a plate provided to the other of the elevator car and the hoistway; a second coil provided on an opposite side of the first coil relative to the plate; a shield wall configured to shield an end portion of the plate located closer to one of the car and the hoistway; and a determination circuit configured to determine a phase of an alternating-current voltage corresponding to a frequency of the excitation magnetic field output from the first coil at an alternating-current voltage generated across the second coil.