Power Tool FET Heat Sink Layout for Continuous Cooling
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Solution Overview
Problem
Power tools with field-effect transistors (FETs) face heat dissipation challenges due to the generation of heat during operation, which existing cooling mechanisms, such as fans and heat sinks, do not adequately address, leading to potential overheating and tool shutdown.
Innovation Solution
A power tool design featuring a housing with an air intake and exhaust, a brushless motor, a fan for cooling air circulation, and a heat sink with specific mounting portions and vertical fins, allowing cooling air to flow through an air gap and around the FETs, enhancing heat dissipation while maintaining airflow through the tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fan-based cooling mechanism is used to circulate air through the housing, then cooling air flow is improved, but the heat dissipation from FETs is insufficient leading to overheating
Solution Approach 1:
The heat sink transitions from a conventional planar structure to a three-dimensional finned structure with vertical fins extending from horizontal fins. This dimensional expansion creates multiple cooling surfaces that interact with the airflow generated by the fan, significantly increasing the heat dissipation capacity while maintaining compatibility with the existing fan-based cooling system.
Solution Approach 2:
The heat sink is divided into multiple mounting portions with vertical fins segmented along the airflow path. This segmentation allows different portions of the heat sink to be strategically positioned to maximize exposure to cooling air, with each fin segment acting as an independent heat dissipation element that contributes to overall thermal management.
2Ease of manufacture
If FETs are mounted on a FET board with conventional heat sink attachment, then electrical functionality is achieved, but thermal contact and heat dissipation are inadequate
Solution Approach 1:
The heat sink is divided into multiple mounting portions that can be separately attached to different FETs on the FET board. Each mounting portion provides direct thermal contact with its corresponding FET, allowing for modular assembly and maintenance of optimal thermal contact pressure while preserving electrical functionality.
Solution Approach 2:
The heat sink incorporates vertical fins that extend perpendicular to the FET board surface, creating a three-dimensional heat dissipation structure. This vertical dimension increases the surface area available for convective heat transfer to the cooling air, significantly enhancing heat dissipation capacity without interfering with the electrical mounting of FETs on the board.
3Area of stationary object
If heat sink mounting portions are positioned close together, then space utilization is improved, but airflow restriction occurs reducing cooling effectiveness
Solution Approach 1:
The heat sink utilizes vertical fins that extend upward from the mounting portions, moving the heat dissipation function into the vertical dimension. This allows the mounting portions to be positioned close together on the FET board (minimizing horizontal footprint) while the vertical fins provide sufficient surface area for heat dissipation without restricting horizontal airflow through the housing.
Solution Approach 2:
The vertical fins are strategically positioned to create localized heat dissipation zones that do not obstruct the overall airflow path through the housing. The fin density and distribution are optimized to provide adequate cooling in specific high-heat areas while maintaining open channels for cooling air to flow freely through the housing.
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 design effectively dissipates heat generated by FETs, preventing overheating and allowing the power tool to operate continuously without shutdown, even at high heat loads, by ensuring efficient airflow and increased heat sink surface area for thermal management.
Implementation Method 1
a fan configured to pull cooling air into the housing through the air intake, and exhaust the cooling air out of the housing through the air exhaust
Implementation Method 2
The heat sink is in thermal contact with the FETs
Implementation Method 3
each of the mounting portions includes a horizontal fin extending toward a respective side of the housing. The heat sink further includes a plurality of vertical fins extending from a top surface of each of the horizontal fins
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
System for cooling a power tool. One exemplary power tool includes a housing including an air intake and an air exhaust. The power tool further includes a motor and a fan configured to pull cooling air into the housing through the air intake, and exhaust the cooling air out of the housing through the air exhaust. The power tool further includes a plurality of field-effect transistors (FETs). The FETs couple the stator coils to a power source. The power tool further includes a FET board within the housing. The power tool further includes a heat sink within the housing. The heat sink includes a first mounting portion and a second mounting portion. Each of the mounting portions includes a horizontal fin extending toward a respective side of the housing. A plurality of vertical fins extends from a top surface of each of the horizontal fins.