Modular Outer-Rotor BLDC Motor Assembly for Compact Power Tools
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Solution Overview
Problem
There is a need for a compact outer-rotor brushless direct-current (BLDC) motor with high power density suitable for portable power tool applications, as existing motors do not adequately meet the requirements for compactness and high power output in lightweight designs.
Innovation Solution
The design incorporates a modular BLDC motor assembly with a stator assembly and an outer rotor, featuring a stator core with radially extending teeth and windings, a cylindrical rotor core with permanent magnets, and a rotor mount with air inlets for airflow, along with a piloting pin mechanism for modular detachment, enabling high power output and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an outer-rotor BLDC motor is used to increase rotor mass and inertia, then power output and torque are improved, but motor size and weight increase
Solution Approach 1:
The motor is divided into modular components including a stator assembly and a rotor assembly that can be separately manufactured and assembled. The stator assembly includes a stator core with windings, while the rotor assembly includes an outer rotor with permanent magnets. This segmentation allows for optimized weight distribution and compact design while maintaining high power output capability.
Solution Approach 2:
The stator assembly is positioned inside the rotor assembly, creating a nested configuration where the stator core with hollow center receives the rotor therein. The rotor mount includes an inner body formed centrally that is supported by radial walls, creating a compact nested structure that maximizes power density while minimizing overall motor size and weight.
2Volume of moving object
If a compact motor design is implemented, then motor size is reduced, but manufacturing complexity increases
Solution Approach 1:
The motor is divided into modular components including a stator assembly and a rotor assembly that can be separately manufactured and assembled. The stator assembly includes a stator core with windings, while the rotor assembly includes an outer rotor with permanent magnets. This segmentation allows for optimized weight distribution and compact design while maintaining high power output capability.
Solution Approach 2:
The stator assembly and rotor assembly are pre-assembled as separate modular units with all components properly positioned and secured before final assembly. The rotor mount includes pre-formed radial walls and an inner body, and the stator mount includes pre-positioned stator teeth and windings, simplifying the final assembly process while achieving compact dimensions.
3Ease of repair
If modular detachable design is used, then ease of repair and maintenance are improved, but device complexity increases
Solution Approach 1:
The motor is divided into modular components including a stator assembly and a rotor assembly that can be separately manufactured and assembled. The stator assembly includes a stator core with windings, while the rotor assembly includes an outer rotor with permanent magnets. This segmentation allows for optimized weight distribution and compact design while maintaining high power output capability.
Solution Approach 2:
The motor design incorporates a detachable connection mechanism using a piloting pin that slidingly receives within the inner race of a motor bearing, allowing the stator assembly to be modularly detached from the rotor assembly. This dynamic design enables easy disassembly for repair and maintenance while maintaining a compact integrated structure during operation, effectively balancing device complexity with ease of repair.
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 achieves a power output of approximately 400 W to 550 W with a maximum speed of 25,000 to 30,000 rpm, providing a high power-to-weight ratio suitable for compact and lightweight power tools, enhancing portability and performance in cutting applications.
Implementation Method 1
a brushless direct-current (BLDC) motor includes a stator assembly including a stator core having an aperture extending therethrough, stator teeth radially extending outwardly from the stator core and defining slots therebetween, and stator windings wound around the stator teeth. The BLDC motor further includes an outer rotor comprising a cylindrical rotor core supporting at least one permanent magnet around an outer surface of the stator core.
Implementation Method 2
a motor bearing having an outer race supported by within the inner body of the rotor mount and an inner race
Data Source
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AI summary
An outer-rotor brushless direct-current (BLDC) motor is provided including a stator core having an aperture extending therethrough, a stator mount including an elongated cylindrical member projecting into the aperture of the stator core, an outer rotor, and a rotor mount including an outer rim arranged to couple to the outer rotor and an inner body supporting an outer race of a motor bearing. A piloting pin is provided including a rear portion received within the hollow portion of the elongated cylindrical member of the stator mount and a front portion received within the inner race of the motor bearing.