Motor Rotor Sensor Layout to Cut Parts and Cogging Torque
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Solution Overview
Problem
The existing motor designs require additional parts for position sensing, increasing manufacturing costs and complexity due to the need for separate sensor magnets and plates, and generate cogging torque during rotation, which affects efficiency.
Innovation Solution
The motor design incorporates a magnetic sensor positioned between a cover and the rotor, directly sensing the magnetic force of the rotor's magnet, reducing the number of parts needed and incorporating a curved outer circumferential surface on the rotor core to minimize cogging torque by varying the distance from the edge region to the teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor is disposed spaced apart from the rotation radius of the rotor and the rotary shaft, then the magnetic sensor can detect the rotation angle of the rotor, but the rotary shaft must be provided with a sensor magnet and a plate separately, increasing the number of parts and manufacturing cost
Solution Approach 1:
The patent combines the sensor magnet and the plate into a single integrated component. The sensor magnet is directly mounted on the rotary shaft, eliminating the need for a separate plate structure. This merging reduces the number of parts while maintaining the magnetic field generation capability necessary for rotation angle detection by the magnetic sensor.
2Ease of manufacture
If the outer circumferential surface of the rotor core is a flat surface, then the structure is simple, but cogging torque is generated during rotation affecting efficiency
Solution Approach 1:
The patent applies curvature to the outer circumferential surface of the rotor core by providing a curved surface instead of a flat surface. This curved surface configuration modifies the magnetic flux distribution during rotor rotation, reducing the cogging torque generated by the interaction between the permanent magnets and the stator teeth. The curvature helps to equalize the magnetic reluctance throughout the rotation cycle, thereby minimizing energy losses.
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 reduces manufacturing costs by eliminating separate sensor magnets and decreases cogging torque, enhancing motor efficiency by directly sensing magnetic forces and optimizing the rotor's surface curvature.
Implementation Method 1
a magnetic sensor disposed between the cover and the rotor, and detecting a magnetic force of the rotor
Implementation Method 2
the motor is rotated by the electromagnetic interaction between the rotor and the stator
Data Source
AI summary
A motor comprises: a shaft; a rotor coupled to the shaft and including a magnet; a stator disposed outside the rotor and including a coil and a stator core; a cover disposed on an upper side of the rotor; and a magnetic sensor disposed between the cover and the rotor, wherein the magnetic sensor is disposed on an upper side of the magnet, a surface of the magnetic sensor facing the rotor is disposed below the uppermost end of the coil, and the length of the rotor in the shaft direction is longer than the length of the stator core in the shaft direction.