Magnetic Rotation Sensor Shaft Positioning
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Solution Overview
Problem
Conventional magnetic rotation detection apparatuses face challenges in achieving high detection accuracy and assembly reliability due to movement of the shaft in the thrust direction, leading to potential assembly failures and decreased magnetic field detection precision.
Innovation Solution
A magnetic rotation detection apparatus with a circuit board and a rotation shaft housed in a container, where a receiving member and biasing member maintain a consistent distance between the magnet and the circuit board, preventing magnetic field intensity changes and internal pressure issues, ensuring accurate rotation angle detection and preventing assembly failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gap is provided between the magnet and the circuit board in the thrust direction, then smooth rotation of the shaft is achieved, but movement of the shaft in the thrust direction occurs, causing changes in magnetic field intensity and reducing detection accuracy
Solution Approach 1:
A receiving member is introduced as an intermediary component between the shaft and the circuit board. This receiving member receives the thrust force from the shaft and transmits it to the circuit board, preventing direct contact while eliminating thrust direction movement. The intermediary structure maintains the necessary gap for smooth rotation while ensuring positional stability for accurate magnetic field detection.
2Measurement precision
If an oil seal is used to hold the shaft with high surface pressure, then movement of the shaft in the thrust direction is suppressed, but assembly failure occurs due to air compression and O-ring displacement
Solution Approach 1:
The oil seal is removed from the assembly, eliminating the source of air compression and O-ring displacement problems. Instead of using the oil seal to suppress shaft movement, the design extracts this function to a receiving member that can be properly integrated into the assembly sequence without creating pressure-related assembly failures.
Solution Approach 2:
The receiving member is designed to be installed before the circuit board, establishing the positional relationship and preventing air entrapment. This preliminary action ensures that when subsequent components are assembled, no air compression occurs that could displace the O-ring and cause assembly failure.
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 enables precise detection of rotation angles with improved assembly reliability by maintaining a consistent magnetic field and preventing internal pressure increases, thus enhancing the accuracy and reliability of the gear position sensor.
Implementation Method 1
a Hall element 124 is provided at the circuit board 122 such that the rotation angle of the shift drum is detected as the Hall element 124 detects a change of magnetic field intensity accompanying rotation of the magnet 123
Data Source
AI summary
A magnetic rotation detection apparatus which is capable of suppressing occurrence of assembly failure of components. A gear position sensor 10 is provided with a sensor unit 12 including a Hall element 20, a magnet shaft 11 including a magnet 17, a case 14 housing the sensor unit 12 and the magnet shaft 11, and an inner O-ring 24 sealing a gap between the sensor unit 12 and the case 14. The case 14 includes a metal bearing 19 to support the magnet shaft 11, and the magnet shaft 11 includes a molded portion 18 to fix the magnet 17. A thrust plate 22 is arranged between the molded portion 18 and a base plate 21 (circuit board) of the sensor unit 12, and a spring mechanism 26 is arranged to bias the molded portion 18 to the thrust plate 22. A minute gap is present between the metal bearing 19 and the magnet shaft 11.