Electronic Switch Module for Power Tools
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Solution Overview
Problem
Conventional power tool switch modules are bulky due to mechanical components, prone to wear, and require separate interfaces for communication, leading to increased size and weight, and inefficiencies in heat dissipation.
Innovation Solution
An electronic switch module integrating a programmable micro-controller, power components, and user-actuated inputs into a single housing, using insulated metal substrates for reduced heat dissipation and incorporating synchronous rectification to replace flyback diodes, allowing for compact and efficient motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical switch components are used for motor control, then the power tool can achieve basic switching functionality, but the size and weight of the tool increase due to bulky mechanical components
Solution Approach 1:
The patent replaces mechanical switch components with an electronic control system consisting of a microcontroller and electronic switching devices. The microcontroller receives user input and generates control signals to electronically switch power to the motor, eliminating the need for mechanical switches, potentiometers, and rheostats. This substitution significantly reduces the size and weight of the power tool while maintaining full switching functionality.
2Temperature
If separate heat sinks are provided for power components, then heat dissipation is effective, but the device size increases
Solution Approach 1:
The patent merges the heat dissipation function into the printed circuit board itself by providing a thermally conductive ground plane on the PCB. This ground plane acts as an integrated heat sink, absorbing and dissipating heat from power components such as MOSFETs and diodes directly at their mounting locations. By combining the structural support, electrical grounding, and thermal management functions into a single PCB layer, the design eliminates the need for separate external heat sinks, thereby reducing overall device size while maintaining effective heat dissipation.
3Ease of manufacture
If multiple separate modules are used for control and power switching, then each module can be optimized independently, but the overall device complexity and number of interfaces increase
Solution Approach 1:
The patent combines the microcontroller, power switching devices, heat dissipation structures, and user input interfaces into a single integrated control module housed within the power tool handle. The microcontroller, electronic switches, thermally conductive ground plane, and input mechanisms share a common housing and control circuitry, eliminating the need for multiple separate modules and their interconnecting interfaces. This integration simplifies the overall device architecture while maintaining the ability to optimize each functional element independently during the design phase.
4Reliability
If mechanical switch components are used, then the switching functionality is reliable, but the components are prone to wear and tear
Solution Approach 1:
The patent replaces all mechanical switching components with solid-state electronic switching devices controlled by a microcontroller. Electronic switches such as MOSFETs have no moving parts, eliminating mechanical wear and tear. The microcontroller-based control system provides precise, wear-free switching with unlimited operational life, significantly improving both reliability and duration of action compared to mechanical switches, potentiometers, and rheostats.
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 reduces the size and weight of power tools by minimizing heat dissipation requirements and eliminating the need for separate heat sinks, while enhancing control precision and durability through integrated electronics.
Implementation Method 1
a thermally conductive ground plane on the power circuit board
Implementation Method 2
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
Figure 1
Figure 2A
Figure 2B
AI summary
An electronic power apparatus is provided, including a circuit board having a conductive pads and a sense pad coupled to an output signal, and an actuator having a wiper portion accommodating a conductive wiper. The wiper includes a first end arranged to engage the sense pad and a second end arranged to slidably engage at least one of the conductive pads on the circuit board. The conductive pads are arranged in a first row of conductive pads and a second row of conductive pads in parallel with and at a distance to the first row of conductive pads. An alignment of the second row of conductive pads is offset with respect to the first row of conductive pads.