Motor Rotor Magnetic Positioning for Stable Sensing
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Solution Overview
Problem
Existing motor designs require a spring with a large spring force to maintain a stable gap between the sensor magnet and the sensor board, leading to increased rotor weight and inertial mass, which decreases responsiveness.
Innovation Solution
The rotor is pressed in the axial direction by magnetic attraction force, using a design where the axial central part of the magnet deviates to oppose the abutment direction of the abutment member, with magnetic attraction force balancing the rotor position and eliminating rattling, while utilizing a lightweight anti-rattle spring to suppress inertial mass increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring with large spring force is used to press the sensor magnet toward the sensor board, then stable sensing is achieved, but rotor weight and inertial mass increase
Solution Approach 1:
The patent replaces the mechanical spring pressing mechanism with a magnetic field-based positioning system. The sensor magnet is positioned using magnetic attraction/repulsion forces between the sensor magnet and the stator core, eliminating the need for mechanical springs and their associated weights while maintaining stable gap control for sensing.
Solution Approach 2:
The patent changes the physical state and interaction mechanism from mechanical contact force (spring) to magnetic field interaction. By adjusting magnetic field strength and distribution, the system achieves stable magnet positioning without the mass penalty of heavy springs, directly resolving the contradiction between reliability and weight.
2Reliability
If a spring with large spring force is used to press the sensor magnet toward the sensor board, then stable sensing is achieved, but inertial mass increases and responsiveness decreases
Solution Approach 1:
The patent substitutes the heavy mechanical spring system with a lightweight magnetic field-based positioning system. This reduction in inertial mass directly improves the rotor's responsiveness and acceleration characteristics while maintaining stable sensing through magnetic field control of the sensor magnet position.
3Reliability
If the axial central part of the magnet deviates to oppose the abutment direction, then magnetic attraction force balances rotor position, but structural design complexity increases
Solution Approach 1:
The patent intentionally introduces asymmetric deviation of the magnet's axial central part relative to the stator core. This asymmetric positioning creates a controlled magnetic attraction force that balances the rotor in the axial direction, counteracting the abutment force from the abutment member. While the positioning is asymmetric, the overall structural complexity remains manageable through straightforward geometric adjustments.
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 design maintains stable sensing and reduces mechanical noise, suppresses inertial mass increase, and optimizes power consumption, aligning with sustainable development goals by minimizing power usage.
Implementation Method 1
the rotor is pressed in the axial direction by magnetic attraction force, using a design where the axial central part of the magnet deviates to oppose the abutment direction of the abutment member, with magnetic attraction force balancing the rotor position and eliminating rattling
Data Source
AI summary
A motor device includes a stator and a rotor. The stator includes: a stator core, fixed radially inside a motor case; and a coil, wound on teeth provided on the stator core. The rotor includes: a rotating shaft, rotatably supported by a bearing fixed to the motor case; a magnet, integrally provided on the rotating shaft; and an abutment member, fixed to the rotating shaft and abutted against the bearing from one axial side of the rotating shaft toward an other axial side of the rotating shaft. An axial central part of the magnet deviates to a side opposite to an abutment direction of the abutment member against the bearing with respect to an axial central part of the stator core.