Brushless DC Motor PCB Layout for Compact Tool Cooling
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Solution Overview
Problem
Brushless motor power tools face complexity in wiring layouts and assembly due to separate printed circuit boards (PCBs) for various components, leading to increased size, reduced flexibility in design, and potential thermal management issues.
Innovation Solution
A combined surfboard PCB layout that integrates FETs, motor control unit, and forward/reverse switch, along with a heat sink, to reduce wiring complexity and enhance thermal management by exposing components for better cooling, allowing for more compact and flexible tool designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate printed circuit boards are used for various components, then functional modularity is improved, but device complexity and wiring layout complexity increase
Solution Approach 1:
The patent combines multiple separate PCBs into a single integrated PCB that houses all control components including FETs, motor control unit, and forward/reverse switch. This merging eliminates the need for complex inter-PCB wiring while maintaining all necessary functional separations through dedicated circuit zones on the unified board.
2Ease of manufacture
If traditional motor mounting is used, then assembly is simplified, but thermal management capability is reduced
Solution Approach 1:
The heat sink is integrated directly with the motor assembly, combining the motor mounting function with thermal dissipation. The heat sink serves dual purposes: providing structural support for mounting the motor while simultaneously acting as a thermal management system to dissipate heat from the motor and power electronics.
Solution Approach 2:
The heat sink acts as an intermediary between the motor and the surrounding environment, facilitating heat transfer from the motor to the air. The heat sink's extended surface area provides an efficient thermal pathway that improves cooling without adding complex active cooling systems.
3Volume of moving object
If compact design is pursued, then tool size is reduced, but thermal management becomes more difficult
Solution Approach 1:
The heat sink is merged with the motor assembly and housing structure, eliminating the need for separate thermal management components. This integration allows the same structural elements to serve both mechanical support and thermal dissipation functions, enabling compact design without compromising cooling capability.
Solution Approach 2:
The heat sink structure performs multiple functions simultaneously: it provides structural support for the motor, serves as a thermal dissipation system, and acts as part of the overall housing structure. This multi-functionality reduces the total component count and enables more compact tool design.
4Power
If higher current levels are achieved, then torque output is improved, but thermal generation increases
Solution Approach 1:
The heat sink serves as an intermediary thermal management system that facilitates efficient heat dissipation from the motor and power electronics. By providing a large surface area for heat transfer to the surrounding air, the heat sink enables the system to sustain higher current levels and torque output without excessive temperature rise.
Solution Approach 2:
The patent replaces complex active cooling systems with a passive thermal management approach using the heat sink. This substitution allows the system to handle higher power levels through improved passive heat dissipation rather than requiring additional active cooling mechanisms.
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 combined surfboard PCB layout reduces assembly complexity, enables more compact designs, improves thermal management, and allows for higher current levels and torque output, extending tool performance and usability.
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
exposing components for better cooling
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.