Motor-Operated Valve Magnetic Coupling for Accurate Position Sensing
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Solution Overview
Problem
The existing motor-operated valve design suffers from assembly difficulties due to the integration of the driving shaft with the gear mechanism, and the rotational angle of the output shaft does not accurately correspond to the position of the valve member due to a gap between the slit and the driving shaft, leading to inaccurate position detection.
Innovation Solution
The motor-operated valve incorporates a driving magnet on the driving shaft, a driven magnet that encloses and is magnetically coupled with the driving magnet, and a magnetic sensor outside the case to detect the rotational angle accurately, eliminating the need for integrating the driving shaft with the output shaft of the gear mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the driving shaft is connected to the output shaft via a slit to allow relative movement, then the assembly is easier to manufacture, but the rotational angle detection accuracy deteriorates due to gap-induced misalignment
Solution Approach 1:
A magnetic transmission member (flux guide) is introduced as an intermediary between the driving magnet on the driving shaft and the driven magnet on the output shaft. This flux guide transmits magnetic flux through the gap, enabling accurate rotational angle detection of the driving shaft without requiring direct mechanical contact, thus resolving the contradiction between assembly ease and detection accuracy.
2Measurement precision
If the driving shaft is integrally connected to the output shaft, then the rotational angle detection accuracy improves, but the device complexity increases due to concurrent mounting and installation requirements
Solution Approach 1:
The system is segmented into independent components: the driving shaft with driving magnet, the output shaft with driven magnet, and the magnetic transmission member. This segmentation allows the driving shaft to be assembled and calibrated independently, then integrated with the gear mechanism, reducing overall assembly complexity while maintaining rotational angle detection accuracy through magnetic coupling.
3Extent of automation
If a permanent magnet and angle sensor are used to detect output shaft rotation, then the valve member position can be detected, but the detection accuracy deteriorates due to the gap between the output shaft slit and driving shaft
Solution Approach 1:
The direct mechanical connection between the driving shaft and output shaft is replaced with a magnetic field-based transmission system. The magnetic transmission member transmits rotational position information magnetically rather than mechanically, eliminating the need for direct contact and thereby maintaining high position detection accuracy despite the presence of gaps.
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
This configuration allows for easier assembly and more accurate detection of the valve member's position, ensuring the rotational angle of the driven magnet coincides with the driving shaft, thereby improving positional accuracy without integrating the driving shaft with the output shaft.
Implementation Method 1
a driving magnet that is mounted on the driving shaft and rotates together with the driving shaft
Implementation Method 2
a driven magnet that has an annular shape and encloses the driving magnet. The driven magnet rotates about the driving shaft in response to rotation of the driving magnet
Implementation Method 3
a magnetic sensor that is disposed outside the case. The magnetic sensor detects magnetism of the driven magnet
Data Source
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AI summary
[Object] To provide a motor-operated valve that is easy to assemble and allows the position of a valve member to be detected more accurately. [Solution] A motor-operated valve 1 includes a valve body 10, a can 30, a driving shaft 70, a planetary gear mechanism 60 that transmits the rotation of a rotor 51 to the driving shaft 70, a valve member 40 that is disposed in a valve chamber 13 of the valve body 10 and changes in position in an up-and-down direction in response to the rotation of the driving shaft 70, and a magnetic sensor 85 that is disposed outside the can 30. The motor-operated valve 1 includes a driving magnet 76 that is mounted on the driving shaft 70 and rotates together with the driving shaft 70, and a driven magnet 77 that has a circular annular shape and encloses the driving magnet 76. The driven magnet 77 rotates about the driving shaft 70 in response to the rotation of the driving magnet 76. The magnetic sensor 85 detects magnetism of the driven magnet 77.