Electronic expansion valve, control system, and control method
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Solution Overview
Problem
The existing technologies for electronic expansion valves with stepping motors face challenges in accurately detecting rotor locking, which can lead to abnormal operation due to either undetected or falsely reported rotor locking issues.
Innovation Solution
An electronic expansion valve system that includes a stepping motor, a Hall sensor, and a controller, where the Hall sensor detects magnetic pole changes and generates feedback signals, allowing the controller to determine normal operation or rotor locking by analyzing the duration of these signals, thereby improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotor locking detection is implemented using existing methods, then rotor locking can be detected, but detection accuracy is insufficient leading to false positives or missed detections
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the Hall sensor signals during stepping motor operation. By comparing the actual Hall signal transitions with expected patterns based on commanded steps, the system can accurately detect rotor locking conditions and provide real-time feedback to prevent abnormal operation.
Solution Approach 2:
The patent replaces mechanical detection methods with electromagnetic sensing using Hall sensors. Instead of mechanical switches or contacts, the system uses Hall sensors to detect the magnetic field position of the rotor, providing non-contact, high-precision detection of rotor position and locking conditions.
2Measurement precision
If Hall sensor is added to improve detection accuracy, then rotor locking detection is enhanced, but device complexity increases
Solution Approach 1:
The Hall sensor serves multiple functions: it provides rotor position information for normal motor control, enables accurate rotor locking detection, and assists in determining valve opening degree. This multi-functionality reduces the need for separate detection mechanisms, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent introduces a dedicated detection mechanism using Hall sensors as intermediaries between the rotor magnetic field and the controller. The Hall sensors convert magnetic field position into electrical signals that the controller can process, providing accurate detection without requiring direct mechanical or complex electrical connections.
3Reliability
If multiple Hall sensors are used to improve detection reliability, then detection accuracy is enhanced, but manufacturing cost increases
Solution Approach 1:
The patent uses a single Hall sensor positioned to detect specific magnetic pole transitions that are critical for determining rotor locking. Instead of using multiple Hall sensors around the entire rotor circumference, the system strategically places one sensor to monitor the most informative magnetic field changes, achieving reliable detection with minimal components.
Solution Approach 2:
The patent achieves improved detection reliability by changing the evaluation parameters rather than increasing sensor quantity. The controller analyzes the timing and pattern of Hall signal transitions relative to commanded stepping sequences, using temporal and pattern-based parameters to detect rotor locking with high reliability using a single sensor.
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 enhances the detection accuracy of rotor locking, reducing the influence of operating conditions and ensuring reliable operation of the electronic expansion valve by providing real-time feedback and emitting locked rotor signals when necessary.
Implementation Method 1
The Hall sensor is configured to sense magnetic pole changes of the permanent magnet and generate Hall signals
Data Source
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AI summary
Provided are an electronic expansion valve (100), a control system, and a control method, comprising: a step motor (10) and a Hall sensor (3); the step motor comprises a rotor (1) and a stator (2); the rotor comprises 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 (31) 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.