Handheld Grinder Motor Control Circuit Thermal Management
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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 functionality, durability, and reliability.
Innovation Solution
A handheld grinder design featuring an elongated housing with a motor case and handle portion, including a planar circuit board and motor drive circuit that incorporates air flow, position sensors, and a heat sink to manage heat and protect components from contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If circuit boards and motor control components are included in the power tool, then the motor control functionality is improved, but heat generation increases
Solution Approach 1:
The housing is divided into separate compartments with thermal barriers between the motor control electronics and the motor, isolating heat sources and directing heat away from sensitive components
Solution Approach 2:
Heat sinks and thermal management components are introduced as intermediaries between the motor control circuitry and the motor to facilitate heat dissipation and protect electronics from excessive heat
2Adaptability or versatility
If the power tool operates in harsh environments, then the versatility and productivity are improved, but contamination of components occurs
Solution Approach 1:
Seals and protective barriers are implemented at interfaces and openings to prevent dust and contaminants from entering the housing and damaging internal components, enabling operation in harsh environments
Solution Approach 2:
The housing creates a protected internal environment that isolates sensitive electronic components from harmful external contaminants like dust and debris
3Extent of automation
If multiple circuit boards and capacitors are included, then the motor control capability is improved, but heat generation and device complexity increase
Solution Approach 1:
Multiple circuit boards are consolidated into a single integrated planar circuit board that accommodates the motor control circuit, capacitor, and other electronic components, reducing the number of separate components while maintaining full motor control functionality
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 reduces heat generation and protects components from contaminants, enhancing the tool's functionality, durability, and reliability in demanding environments.
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 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 handheld grinder includes an elongated housing, an electric motor, an output shaft, a wall, a planar circuit board, and a motor drive circuit. The elongated housing defines a cavity therein and includes a motor case disposed at a front end and a handle portion to a rear end. The electric motor has a drive shaft that is mounted within the motor case. The output shaft is drivably coupled to the drive shaft of the electric motor. The wall separates the cavity between the motor case and the handle portion of the housing. The planar circuit board is disposed in the handle portion of the housing. The motor drive circuit is accommodated entirely within the handle portion of the housing on the planar circuit board.