Brushless Motor Detector Mount Reduces Axial Length
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Solution Overview
Problem
Conventional brushless motors require a larger axial length to maintain magnetic flux for position detection, increasing cost and size, while existing solutions do not effectively reduce motor thickness or cost.
Innovation Solution
A brushless motor design featuring a columnar rotor with magnets, a stator with a housing member that includes a first support member with a detector mount projecting towards the rotor end face, allowing for precise signal detection without magnet overhang, thus reducing motor thickness and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotor magnet is caused to overhang from the rotor end face to maintain the distance between the rotor magnet and the position detection element, then the magnetic flux for position detection is increased, but the axial length of the motor becomes larger
Solution Approach 1:
The patent changes the spatial arrangement by moving the detector from a position requiring magnet overhang to a position on the end face of the rotor. This dimensional repositioning allows the detector to be located at the rotor's end face rather than requiring axial extension through magnet overhang, thus reducing axial length while maintaining detection capability through alternative magnetic flux paths.
2Measurement precision
If the rotor magnet is caused to overhang from the rotor end face to maintain the distance between the rotor magnet and the position detection element, then the magnetic flux for position detection is increased, but the cost increases due to the use of additional magnet material
Solution Approach 1:
The patent extracts the function of position detection from the rotor magnet structure itself. By placing the detector on the end face of the rotor to directly detect magnetic flux from the magnets, the system separates the detection function from the need for magnet overhang, eliminating the additional magnet material required for detection purposes while maintaining adequate magnetic flux for accurate position sensing.
3Length of moving object
If the detector is placed closer to the rotor end face, then the motor size is reduced, but the signal detection precision may be compromised
Solution Approach 1:
The patent performs preliminary positioning of the detector on the end face of the rotor at an optimized location. This preliminary placement allows the detector to be positioned in advance at the optimal point where magnetic flux from the magnets is sufficiently strong for accurate detection, eliminating the need for magnet overhang while maintaining detection precision through careful initial positioning.
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 design improves signal detection precision and reduces motor thickness and cost by placing the detector closer to the rotor, eliminating the need for magnet overhang and optimizing the use of space.
Implementation Method 1
a detector that detects a signal dependent on a rotational position of the rotor based on variation in a magnetic field associated with a rotation of the rotor
Data Source
AI summary
A brushless motor includes: a columnar rotor including magnets; a stator including at its center a space for placing the rotor; a housing member that houses the rotor and the stator; and a detector that detects a signal dependent on a rotational position of the rotor based on variation in a magnetic field associated with a rotation of the rotor.The housing member includes a front bell that supports a portion of the rotating shaft of the rotor and a housing body that supports another portion of the rotating shaft of the rotor. The front bell includes a mount fitted with the detector. The mount projects from the base toward an end face of the rotor.