Outer Rotor BLDC Blower Assembly for Power Tool Cooling and Torque
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Solution Overview
Problem
Existing power tool drive units face challenges in efficiently integrating a motor and a blower assembly, particularly in terms of cooling airflow and torque output, which affects the performance and efficiency of the power tool.
Innovation Solution
The drive unit incorporates a brushless direct current (BLDC) outer rotor motor with a rotor shaft, stator, and rotor, where the rotor has a rotor core, magnets, and an overmold housing forming poles with multiple magnets. The blower assembly includes fan blades extending radially from the motor, and the motor fan induces cooling airflow through the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the motor and blower assembly are integrated in existing power tools, then the device complexity is reduced, but the cooling efficiency and torque output are insufficient
Solution Approach 1:
The blower assembly is integrated with the motor assembly such that the blower housing is formed as a single piece with the motor housing, and the blower fan is directly coupled to the motor shaft. This merging maintains low device complexity while improving cooling efficiency through optimized airflow paths and direct drive connection.
2Device complexity
If the motor and blower assembly are integrated in existing power tools, then the device complexity is reduced, but the torque output is insufficient
Solution Approach 1:
The direct coupling of the blower fan to the motor shaft eliminates intermediate transmission components, ensuring maximum torque transfer from the motor to the blower assembly. This direct drive integration maintains structural simplicity while optimizing torque output for enhanced power tool performance.
3Ease of manufacture
If conventional motor configurations are used, then the manufacturing process is simpler, but the aerodynamic performance is suboptimal
Solution Approach 1:
The blower fan blades are designed with specific aerodynamic profiles and angles optimized for airflow generation, while the motor housing incorporates integrated air intake and exhaust passages. This localized optimization of different components' geometries enhances overall aerodynamic performance without complicating the manufacturing process.
4Productivity
If the blower assembly is separately mounted, then the aerodynamic performance can be optimized, but the stress on components increases
Solution Approach 1:
The blower assembly and motor assembly are merged into a single integrated unit with a unified housing structure. This integration reduces the number of separate mounting connections and fasteners, thereby minimizing stress concentration points and potential failure modes while maintaining aerodynamic efficiency.
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 configuration enhances the power tool's performance by improving cooling efficiency, increasing torque output, and extending the drive unit's lifespan by minimizing stress on components and optimizing aerodynamic performance.
Implementation Method 1
The motor includes a rotor shaft, a stator, and a rotor. The rotor shaft extends along an axis of rotation. The stator is mounted to the rotor shaft. The rotor at least partially surrounds the stator.
Implementation Method 2
The blower assembly is configured to be driven by the motor, and the motor fan induces cooling airflow through the motor.
Data Source
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AI summary
A drive unit for a power tool that includes a motor and a blower assembly. The motor includes a rotor shaft, a stator, and a rotor. The rotor shaft extends along an axis of rotation. The stator is mounted to the rotor shaft. The rotor at least partially surrounds the stator. The rotor has a rotor core, a plurality of magnets, and an overmold housing that couples the plurality of magnets to the rotor core to form poles having more than one magnet per pole. The blower assembly includes a plurality of blower fan blades. The blower assembly is configured to be driven by the motor.