Axial Rotor Magnet Layout for Stable Hall Sensing
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Solution Overview
Problem
Existing motor designs require a spring with a large spring force to press a sensor magnet against a sensor board, leading to increased rotor weight and inertial mass, which decreases responsiveness.
Innovation Solution
A motor device where the rotor is pressed in the axial direction by magnetic attraction force, using a stator and rotor configuration with a magnet and abutment member, and an anti-rattle spring to maintain stable sensing without increasing inertial mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring with large spring force is used to press the sensor magnet against the sensor board, then stable sensing is achieved, but the rotor weight and inertial mass increase, leading to decreased responsiveness
Solution Approach 1:
The patent replaces the mechanical spring pressing mechanism with a magnetic field-based pressing mechanism. The stator core generates magnetic attraction force that presses the rotor (including the sensor magnet) against the sensor board, eliminating the need for a heavy mechanical spring while maintaining stable sensing contact
2Reliability
If a spring with large spring force is used to press the sensor magnet against the sensor board, then stable sensing is achieved, but the inertial mass increases, leading to decreased responsiveness
Solution Approach 1:
The patent substitutes the mechanical spring system with an electromagnetic system where the stator core generates magnetic attraction force. This replacement eliminates the heavy spring component, reducing inertial mass and improving rotational responsiveness while maintaining stable sensing through magnetic pressing
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 motor device achieves stable sensing while suppressing inertial mass increase, reducing mechanical noise, and optimizing power consumption.
Implementation Method 1
a rotor can be pressed in an axial direction by magnetic attraction force
Data Source
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AI summary
An axial central part of a ring magnet (43) deviates to a side opposite to an abutment direction of an abutment member (44) against a first ball bearing (23), with respect to an axial central part of a stator core (31). Thus, by supplying drive current to a coil (34) and driving an electric motor part (20), magnetic attraction force (MF) can be generated that attempts to move a rotor (40) toward the other axial side. Due to the action of the magnetic attraction force (MF), the occurrence of rattling and deviation of the axial position of the rotor (40) can be eliminated. Consequently, a constant separation distance between the ring magnet (43) and Hall elements (Hu, Hv, and Hw) in the axial direction of the rotating shaft (41) can be maintained, and stable sensing can be performed while an increase in inertial mass is suppressed.