Brushless Motor Switching Elements Surface Mount Compact Housing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power tools with brushless motors face challenges in minimizing the length of the housing due to the arrangement of switching elements, which affects cooling and heat dissipation, leading to increased size and reduced reliability.
Innovation Solution
The use of semiconductor switching elements with surface mounting on a circuit board, where the elements are fixed with soldered drain terminals and coated with resin for enhanced heat dissipation and stability, allowing for a compact design by orienting the elements to align with the motor's rotation axis and utilizing the existing cooling airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching elements are mounted with legs passing through through holes and fixed by soldering from the rear side, then reliable electrical connection is achieved, but the longitudinal length of the housing becomes long
Solution Approach 1:
The patent replaces the through-hole insertion and rear-side soldering method with surface mounting technology. The switching elements are mounted on the front surface of the circuit board and fixed by soldering their terminal electrodes directly to soldering electrodes on the board surface, eliminating the need for through holes and rear-side assembly. This substitution of mounting methodology reduces the housing longitudinal length while maintaining electrical connection reliability.
2Temperature
If switching elements are disposed with height direction parallel to motor rotation shaft for cooling, then cooling performance is improved, but the space required on the rear side increases
Solution Approach 1:
The patent inverts the conventional mounting orientation by disposing switching elements on the front surface of the circuit board (facing the tip end tool) rather than on the rear side. The elements are arranged with their longitudinal directions substantially parallel to the motor rotation shaft, maintaining effective cooling while eliminating the need for rear-side space accommodation.
Solution Approach 2:
The patent transitions from rear-side mounting to front-surface mounting, utilizing the available space on the front surface of the circuit board. This dimensional relocation allows switching elements to be positioned in a different spatial plane, achieving both cooling efficiency and compact housing design.
3Length of moving object
If circuit board is positioned at another location to avoid increased housing length, then housing size is reduced, but wiring length increases and heat dissipation becomes difficult
Solution Approach 1:
The patent positions the circuit board on the motor rear surface, utilizing the motor's own structure and cooling airflow. The switching elements are mounted on the front surface of this circuit board, allowing them to be cooled by the motor's rotation-induced airflow while maintaining short wiring connections to the motor coils, thus achieving compact housing without increased wiring length or heat dissipation problems.
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 configuration reduces the size of the power tool, improves reliability, and enhances cooling efficiency, resulting in a more compact and effective power tool design.
Implementation Method 1
coated with resin for enhanced heat dissipation
Implementation Method 2
fixed with soldered drain terminals
Data Source
Figure 1
Figure 2
Figure 3
AI summary
According to an aspect of the present invention, there is provided a power tool including: a brushless motor; switching elements that drive the brushless motor; a circuit board on which the switching elements are mounted; a transmission portion that transmits a driving force of the brushless motor; and a housing that houses the brushless motor, the switching elements, the circuit board and the transmission portion therein, wherein the switching elements include semiconductor elements each having terminals on a bottom surface thereof, and wherein the switching elements are surface mounted on the circuit board.