Electronic expansion valve, control system, and control method
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Solution Overview
Problem
The existing electronic expansion valve systems face issues with rotor locking of stepping motors, which can lead to abnormal operation due to inaccurate detection or false reporting by controllers, affecting the overall performance of the system.
Innovation Solution
The proposed solution includes an electronic expansion valve with a Hall sensor and a circuit board, where the Hall sensor is strategically positioned to detect magnetic pole changes of a permanent magnet with multiple pairs of magnetic poles, and a controller acquires feedback signals in real-time to determine normal operation or rotor locking, thereby improving detection accuracy and addressing rotor locking issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Hall sensor is positioned close to the permanent magnet to improve detection sensitivity, then the detection accuracy of magnetic pole changes is improved, but the sensor may be affected by interference from the stator core or other components
Solution Approach 1:
The patent divides the sensor arrangement into distinct functional zones: the Hall sensor is positioned in the air gap region separate from the stator core, with the magnetic conductive portion acting as an intermediary. This spatial segmentation allows the sensor to detect magnetic field changes accurately while being isolated from direct interference by the stator core structure.
Solution Approach 2:
The magnetic conductive portion serves as an intermediary element between the permanent magnet and the Hall sensor. It channels and concentrates the magnetic flux from the permanent magnet toward the sensor location, enhancing the magnetic field strength at the sensor while the sensor itself remains positioned away from the stator core, thus maintaining detection accuracy without direct exposure to stator interference.
2Device complexity
If the controller uses simple detection methods to reduce complexity, then the device complexity is reduced, but the rotor locking detection accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the Hall sensor continuously monitors magnetic pole changes and provides real-time feedback signals to the controller. The controller compares the detected magnetic pole position with the expected position based on rotor rotation, and when a discrepancy is detected (indicating rotor locking), it triggers appropriate protective actions. This feedback-based approach enables accurate rotor locking detection without requiring complex computational algorithms.
3Measurement precision
If the Hall sensor is positioned at the periphery of the permanent magnet to detect magnetic pole changes, then the detection capability is improved, but the sensor may be exposed to harsh operating conditions
Solution Approach 1:
The patent segments the sensor system into two distinct parts: the sensing element (Hall sensor) positioned in the relatively protected air gap region, and the magnetic conductive portion that extends closer to the permanent magnet. This segmentation allows the sensitive Hall sensor to remain in a more favorable environment while still achieving accurate detection of magnetic pole changes through the magnetic field conducted by the magnetic conductive portion.
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 independent Hall sensor enhances detection accuracy, reducing the influence of operating conditions and enabling precise determination of rotor locking, ensuring normal operation of the electronic expansion valve.
Implementation Method 1
The Hall sensor includes a body portion and a connecting portion, both the connecting portion and the coil are electrically connected to the circuit board, and the body portion is configured to sense magnetic pole changes of the permanent magnet
Data Source
AI summary
Provided are an electronic expansion valve, a control system, and a control method, including: a step motor and a Hall sensor; the step motor includes a rotor and a stator; the rotor includes a permanent magnet; the Hall sensor is provided on the outer periphery of the permanent magnet; the Hall sensor and rotor are arranged in the radial direction, and the stator and Hall sensor are arranged in the axial direction; the main-body part of the Hall sensor is used for sensing the magnetic pole change of said permanent magnet; such a structure reduces the effect that an operating environment has on the Hall sensor when detecting a signal.