Brushless Power Tool Circuit Layout for Heat and Dust Control
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Solution Overview
Problem
Power tools with brushless electric motors face contamination issues and heat generation problems in harsh environments, affecting their function, durability, and reliability.
Innovation Solution
A handheld grinder design featuring a brushless electric motor with a motor drive circuit, planar circuit board, and air flow holes to reduce contamination and heat, including a link capacitor and auxiliary capacitor for efficient power management, and a heat sink for thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If multiple circuit boards with capacitors and power switches are included to support brushless motor control, then the motor control functionality is improved, but heat generation increases
Solution Approach 1:
The patent combines multiple circuit boards into a single integrated circuit board that houses all motor control components including the brushless motor controller, rectifier, capacitors, and power switches. This consolidation reduces the overall component count and minimizes heat generation by eliminating redundant circuitry while maintaining full motor control functionality.
2Adaptability or versatility
If circuit boards with multiple components are placed inside the housing to control the brushless motor, then the motor control capability is enhanced, but heat generation increases
Solution Approach 1:
The patent integrates the rectifier, capacitors, and power switches directly onto the same circuit board as the motor controller, creating a unified power electronics system. This merging approach maintains enhanced motor control capability while reducing heat generation by eliminating the need for separate circuit boards and reducing overall system complexity.
3Power
If traditional motor control components are used in power tools, then the motor functionality is maintained, but contamination from dust and debris affects component reliability
Solution Approach 1:
The patent employs a sealed housing structure with integrated circuit boards that are protected from environmental contaminants. The consolidation of components into a unified, enclosed system prevents dust and debris from reaching sensitive electronic components, thereby maintaining motor functionality while significantly improving component reliability in harsh work environments.
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 protects components from contamination, reduces heat generation, and enhances the reliability and durability of the power tool by improving airflow and thermal management.
Implementation Method 1
The auxiliary capacitor has a capacitance more than the capacitance of the link capacitor and is electrically coupled across the DC power bus
Implementation Method 2
The wall separates the cavity between the motor case and the handle portion of the housing and is configured to support a rear bearing for the drive shaft of the electric motor and includes one or more holes which permit air flow between the motor case and the handle portion of the housing
Data Source
AI summary
A power tool comprising: a housing including a motor case and a handle portion extending along a longitudinal axis of the housing from the motor case; an electric motor having a drive shaft and mounted within the motor case; a partitioning wall extending radially between the motor case and the handle portion and forming a bearing pocket therein; a rear bearing mounted on the drive shaft and received into the bearing pocket to support the drive shaft relative to the housing; two elongate walls extending rearwardly from the partitioning wall along two sides of the handle portion; a power control module supported by the two elongate walls within the handle portion, the power control module including a circuit board having a motor drive circuit configured to drive the electric motor; and at least one cover secured to the two elongate walls to cover the circuit board.