Electronic Expansion Valve Hall Sensor Layout for Rotor Lock Detection
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Solution Overview
Problem
The stability of detecting elements in electronic expansion valves is compromised due to rotor locking in stepping motors, necessitating a reliable method to detect normal operation.
Innovation Solution
An electronic expansion valve design incorporating a Hall sensor positioned around a permanent magnet with a sensing portion and connecting portion, fixedly connected to a circuit board, to detect magnetic pole changes and ensure stable detection signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a detecting element is added to detect the operating state of the electronic expansion valve, then the reliability of operation detection is improved, but the device complexity increases
Solution Approach 1:
The permanent magnet on the rotor serves dual purposes: it generates the magnetic field necessary for motor operation and simultaneously acts as the detection target for the Hall sensor. This self-service approach eliminates the need for separate detection components, improving reliability while avoiding increased device complexity
Solution Approach 2:
The magnetic field generated by the permanent magnet performs multiple functions: it enables motor operation through interaction with the stator coil and provides detection information for the Hall sensor. This multi-functionality resolves the contradiction by using existing components for dual purposes rather than adding separate detection elements
2Measurement precision
If the Hall sensor is positioned close to the permanent magnet for accurate detection, then the measurement precision is improved, but the stability of the detection signal deteriorates due to rotor locking
Solution Approach 1:
The Hall sensor detects magnetic pole changes indirectly through the magnetic field distribution changes caused by rotor position, rather than requiring direct contact or extremely close proximity to the permanent magnet. This intermediary detection method maintains measurement precision while avoiding the instability caused by rotor locking
Solution Approach 2:
The Hall sensor provides feedback on rotor position through detection of magnetic pole changes, enabling the control system to monitor and correct for rotor locking conditions. This feedback mechanism ensures stable detection signals by continuously tracking the actual rotor position and comparing it with expected position
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 solution effectively detects magnetic pole changes, improving the stability of detection signals and preventing rotor locking, thereby ensuring the electronic expansion valve operates reliably.
Implementation Method 1
The Hall sensor comprises a sensing portion and a connecting portion, and the sensing portion is electrically connected to the circuit board through the connecting portion and is configured to sense a magnetic pole change of the permanent magnet
Data Source
AI summary
An electronic expansion valve including a rotor, a stator and a circuit board the rotor includes a permanent magnet, and the permanent magnet includes at least two pairs of magnetic poles; the stator includes a coil and a bobbin, wherein the coil is supported by the bobbin, and the bobbin is disposed at the periphery of the permanent magnet. Also included is a Hall sensor, which is disposed on the periphery of the permanent magnet; the Hall sensor and the coil are electrically connected to the circuit board; the Hall sensor includes a sensing portion, and the sensing portion is used for sensing magnetic pole change of the permanent magnet; the sensing portion is always located between the two ends of the permanent magnet during the entire operating process of the rotor.