Power Tool Switch Module Layout for Higher Current Heat Dissipation
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Solution Overview
Problem
Cordless power tools with brushless DC motors face challenges in heat dissipation as larger power devices, such as FETs or IGBTs, generate significant heat, requiring an integrated power, control, and switch module that effectively manages heat dissipation.
Innovation Solution
An electronic control module with a printed circuit board, heat sinks, and a secondary heat sink configuration that enhances heat transfer and dissipation, allowing for improved performance in high-power applications by reducing temperature increases during continuous use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If larger power devices (FETs or IGBTs) are used to meet higher power requirements, then power capability increases, but heat generation increases significantly
Solution Approach 1:
The patent transitions from planar heat dissipation to three-dimensional heat management by implementing heat sinks with vertical fins and multi-layer thermal pathways. The heat sink structure extends in the vertical dimension with fin arrays that increase surface area for convection, while thermal vias conduct heat through multiple PCB layers to dedicated heat dissipation zones, effectively utilizing the Z-axis for heat transport.
Solution Approach 2:
The patent introduces thermal paste as an intermediary substance between the power devices and heat sinks, and thermal vias as intermediary heat conduction pathways through the PCB substrate. These intermediaries bridge the thermal gap between heat-generating components and heat dissipation structures, improving overall thermal coupling and efficiency.
2Power
If larger power devices are used to handle higher current, then current capability increases, but heat dissipation requirements become more stringent
Solution Approach 1:
The patent combines multiple heat dissipation mechanisms into a unified system: conduction through thermal vias in the PCB, convection through heat sink fins, and radiation from exposed surfaces. The electrical ground planes are also merged with thermal management functions by using them as heat sinks themselves, creating a multi-functional integrated solution.
Solution Approach 2:
The PCB ground planes serve dual functions as both electrical return paths and heat dissipation surfaces. The heat sink structure simultaneously provides mechanical support for power devices, thermal conduction pathways, and convective heat dissipation surfaces. This multi-functionality reduces the need for separate dedicated heat dissipation components.
3Productivity
If an integrated power, control, and switch module is implemented, then system efficiency improves, but heat concentration in one location increases
Solution Approach 1:
The integrated module is segmented into distinct functional zones: power device areas with heavy heat generation, control circuit areas with minimal heat, and switch components. Each zone has dedicated thermal pathways and heat sink attachments optimized for its specific heat generation characteristics, allowing differentiated thermal management within the integrated structure.
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 effectively manages heat dissipation, enabling the electronic control module to handle higher power and current requirements, maintaining component temperatures below 120°C and increasing steady-state capability from 40 amps to approximately 70 amps.
Implementation Method 1
heat sinks, and a secondary heat sink configuration that enhances heat transfer and dissipation
Implementation Method 2
heat sinks, and a secondary heat sink configuration that enhances heat transfer and dissipation
Implementation Method 3
A set of sense magnets coupled to the PMs in the rotor assembly are sensed by a sensor, such as a Hall Effect sensor, to identify the current position of the rotor assembly
Data Source
AI summary
An electronic switch module includes a circuit board having conductive pads coupled to a power source and a sense pad coupled to an output signal; and a variable-speed actuator assembly having an actuator positioned adjacent a side edge of the circuit board and moveable along a movement axis, a plunger coupled to the actuator, and a conductive wiper secured to the plunger in contact with the circuit board. The wiper includes a first leg arranged to slidably engage the sense pad and a second leg arranged to slidably engage at least one of the conductive pads. The sense pad is longitudinally aligned with the conductive pads. The first leg of the wiper is located between the actuator and the second leg, and the sense pad is located between the side edge of the circuit board and the conductive pads.