Brushless DC Motor Assembly With Coaxial PCB and Heat Sink
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Solution Overview
Problem
Brushless motor power tools face challenges in thermal management and wiring complexity, leading to reduced efficiency and flexibility in design due to the conventional layout of separate printed circuit boards and heat sinks.
Innovation Solution
A compact and efficient layout featuring a combined surfboard PCB that integrates FETs, a motor control unit, and a Hall sensor, along with an exposed heat sink configuration, reduces wiring and enhances thermal management, allowing for higher current levels and torque output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If separate printed circuit boards and heat sinks are used in conventional layout, then thermal management is achieved, but wiring complexity increases and design flexibility is reduced
Solution Approach 1:
The patent combines the printed circuit board and heat sink into a single integrated component structure. The PCB is mounted directly on the heat sink surface, eliminating separate mounting brackets, fasteners, and wiring harnesses. This integration reduces the number of parts, simplifies assembly, and decreases wiring complexity while maintaining both thermal management and electrical functionality.
2Adaptability or versatility
If separate printed circuit boards and heat sinks are used in conventional layout, then thermal management is achieved, but design flexibility is reduced
Solution Approach 1:
The integrated design merges the PCB mounting surface with the heat sink structure, allowing thermal management functionality to be built into the base structure itself. The PCB mounts directly on the heat dissipation surface, ensuring continuous thermal contact while enabling flexible component placement and routing options that would not be possible with separate discrete components.
3Device complexity
If integrated surfboard PCB with exposed heat sink is used, then wiring complexity is reduced and design flexibility is enhanced, but thermal management effectiveness may be compromised
Solution Approach 1:
The integration of the PCB directly onto the heat sink surface creates a unified structure where the PCB serves as both the electrical circuit carrier and the thermal management interface. The exposed heat sink surface provides direct thermal contact with the PCB-mounted components, ensuring effective heat dissipation while maintaining wiring simplicity and design flexibility.
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 solution improves thermal management and reduces wiring complexity, enabling higher power levels and longer operation times with increased design flexibility for brushless motor power tools.
Implementation Method 1
a heat sink positioned at a second end of the brushless DC motor opposite the first end such that the brushless DC motor is between the heat sink and the annular metal end piece
Implementation Method 2
an exposed heat sink configuration, reduces wiring and enhances thermal management
Data Source
AI summary
A power tool with a combined printed circuit board (PCB) having a doughnut shape and located coaxially with a motor shaft. The combined PCB is secured to a heat sink on one end of the motor and a metal end piece is positioned on an opposite end of the motor. The metal end cap and heat sink are secured to one another via fasteners to provide a rigid coupling. A tabbed end piece is provided between the heat sink and the motor stator and is also secured into place via the fasteners. The tabbed end piece includes wire support tabs that provide strain relief to motor coil leads. The wire support tabs extend axially from circumferential locations of the tabbed end piece and include channels to guide the motor coil leads to solder contact points on the combined PCB.