Brushless Power Tool PCB Layout for Reduced Wiring and Cooling
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Solution Overview
Problem
The complex wiring situation within brushless power tools due to numerous interconnections between components leads to space constraints, increased size, and assembly complexity, limiting design flexibility and thermal management.
Innovation Solution
A compact and efficient layout is achieved by integrating multiple printed circuit boards (PCBs) such as a combined surfboard PCB or doughnut-shaped PCBs, which reduce wiring complexity and allow for improved thermal management through exposed components and strategic placement, enabling shorter connections and enhanced air flow for cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate PCBs are used for control and power switching elements, then functional separation is achieved, but wiring complexity and device size increase
Solution Approach 1:
The patent combines the control PCB and power switching PCB into a single integrated PCB assembly. The control circuitry and power switching elements are mounted on the same PCB substrate, eliminating the need for extensive inter-PCB wiring while maintaining functional separation through distinct circuit regions and layers. This integration directly resolves the wiring complexity issue while preserving reliability through maintained functional boundaries.
2Reliability
If multiple separate PCBs are used, then component functionality is maintained, but the overall device size and space requirements increase
Solution Approach 1:
The control PCB and power switching PCB are merged into a single PCB assembly, significantly reducing the overall device volume. The integrated design allows components to be positioned in optimal locations on the same substrate, eliminating the space required for separate PCB mounting areas and reducing the envelope size of the motor controller.
Solution Approach 2:
The power switching elements are mounted on one side of the PCB while the control circuitry is positioned on the opposite side or in adjacent regions, creating a nested arrangement where functional blocks are contained within the same physical footprint. This nesting approach maintains component functionality while minimizing the overall device size.
3Reliability
If complex wiring is used to connect multiple components, then all electrical connections are established, but assembly complexity and manufacturing difficulty increase
Solution Approach 1:
By integrating control and power switching circuits onto a single PCB, the number of external wiring connections is dramatically reduced. All electrical connections between control and power elements are established through standard PCB traces and vias, which are manufactured automatically during PCB fabrication, eliminating complex manual wiring assembly steps.
Solution Approach 2:
The patent replaces mechanical wiring connections with electrical traces on the PCB substrate. This substitution transforms complex manual wiring assembly into an automated PCB manufacturing process, significantly improving ease of manufacture while maintaining reliable electrical connections.
4Object-affected harmful factors
If components are enclosed in housing, then protection is provided, but thermal management and air flow for cooling are restricted
Solution Approach 1:
The patent incorporates openings and vents in the housing structure that allow air flow paths to reach the PCB components. These strategic openings provide thermal management by enabling convective cooling while maintaining protective enclosure for the internal components. The housing design balances protection with thermal dissipation needs.
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 layout results in a more compact, simplified assembly, improved thermal control, and increased design flexibility for brushless power tools, allowing for various handle and body dimensions while maintaining performance and reducing wiring and assembly complexity.
Implementation Method 1
a heat sink secured to an end of the brushless DC motor
Implementation Method 2
improved air flow for cooling
Data Source
AI summary
A power tool with a combined printed circuit board (PCB) that reduces internal wiring of the power tool and provides a large amount of air flow to internal components. In some instances, the combined PCB has a surfboard shape and includes a motor control unit and power switching elements (Field Effect Transistors or FETs). The combined surfboard PCB is located above the trigger, but below the motor and drive mechanism. In other instances, the combined PCB has a doughnut shape and is located coaxially with a motor shaft. The combined PCB may be positioned between a doughnut-shaped control PCB and the motor.