Brushless Motor Sensor Substrate Mounting on Stator Core
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Solution Overview
Problem
Existing methods for mounting a sensor substrate in brushless motors, such as those described in Patent Literatures 1 and 2, result in elongated motor dimensions and increased material costs due to the use of long axial permanent magnets, and additional complexity and labor in thermal deformation methods, as seen in Patent Literature 3.
Innovation Solution
A brushless motor design where a position detection element, like a Hall IC, is arranged near the permanent magnet on the rotor, utilizing stator covers with pedestal parts, locking portions, and positioning pins to securely mount the sensor substrate without elongating the rotor's axial dimension, incorporating stopper walls and claw portions for secure fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor substrate is mounted on the coil end of stator winding, then the rotational position detection element can be positioned, but the detection element becomes distant from the permanent magnet of the rotor, causing problems in magnetic pole detection
Solution Approach 1:
The patent transitions from radial mounting (on coil end) to axial mounting (on stator core end surface), changing the dimensional approach to resolve the contradiction between detection accuracy and mounting position
2Measurement precision
If permanent magnet and magnetic portion of rotor are made long in axial direction to improve detection, then the dimension of motor in axial direction becomes long and additional material costs are required
Solution Approach 1:
The patent separates the sensor mounting function from the permanent magnet structure, placing the sensor substrate on the stator core end surface rather than relying on extended permanent magnets, thus segmenting the detection system from the magnetic field generation system
Solution Approach 2:
The patent introduces a sensor substrate as an intermediary component that bridges the stator and rotor, providing accurate magnetic pole detection without requiring extended permanent magnets or complex thermal deformation processes
3Reliability
If pins are thermally deformed to fix printed board, then the printed board can be fixed, but large space and additional labor and time are required due to new additional processes
Solution Approach 1:
The sensor substrate utilizes the stator core end surface and stator cover as self-provided mounting structures, eliminating the need for separate thermal deformation processes or additional fixing jigs
Solution Approach 2:
The patent merges the sensor substrate mounting function with the existing stator core and stator cover structures, combining multiple functions into unified components rather than adding separate fixing mechanisms
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention provides a method and a structure for mounting a sensor substrate of a brushless motor, in which a rotation detection element is arranged near a permanent magnet of a rotor and the sensor substrate can be securely mounted with a simple method, and thus, it is not necessary to elongate the dimension of the permanent magnet of the rotor in an axial direction. In the present invention, insulating members that insulate a location for winding of a stator coil from an outside are formed on a stator core (20) on which radially arranged pole teeth (20b) are provided on an inner peripheral surface side of the stator core (20) with a predetermined space, a stator coil is wound around the pole teeth via the insulating members, stopper walls (83) for preventing the coming off of the stator coil are provided to the pole teeth of the insulating member on a leading edge thereof, pedestal parts (84) are formed on the stopper walls (83) on an inner periphery surface side thereof, a sensor substrate (9) to which a position detection element which detects the position of a permanent magnet (30) provided to a rotor (3) is arranged on the pedestal parts (84), locking portions for locking the sensor substrate (9) are provided to some of the pedestal parts (84), and thereby the coming off of the sensor substrate (9) in an axial direction is prevented.