Stator-Wound Braking Coil for Compact Power Tool Motors
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Solution Overview
Problem
Braking resistors and heat sinks in power tools increase manufacturing costs and complicate the form factor due to excess heat generation and the need for additional components.
Innovation Solution
Incorporating a motor braking coil wound around the stator of a brushless DC motor, which dissipates heat through the stator core or airflow, eliminating the need for external resistors and heat sinks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external braking resistors and heat sinks are used, then motor braking function is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The braking resistor function is merged with the motor stator by winding the braking coil around the stator core. This integration eliminates the need for separate external resistors and heat sinks, reducing device complexity while maintaining the motor braking function through the stator's inherent heat dissipation capabilities
Solution Approach 2:
The stator is given multiple functions: it serves both as the motor's electromagnetic component and as the braking resistor through the wound coil. This multi-functionality approach eliminates dedicated braking components, simplifying the overall device structure
2Reliability
If external braking resistors and heat sinks are used, then motor braking function is achieved, but manufacturing cost increases
Solution Approach 1:
The braking resistor function is merged with the motor stator by winding the braking coil around the stator core. This integration eliminates the need for separate external resistors and heat sinks, reducing device complexity while maintaining the motor braking function through the stator's inherent heat dissipation capabilities
Solution Approach 2:
The stator is given multiple functions: it serves both as the motor's electromagnetic component and as the braking resistor through the wound coil. This multi-functionality approach eliminates dedicated braking components, simplifying the overall device structure
3Reliability
If braking resistors are placed outside the motor, then braking function is achieved, but the form factor is complicated
Solution Approach 1:
The braking resistor function is merged with the motor stator by winding the braking coil around the stator core. This integration eliminates the need for separate external resistors and heat sinks, reducing device complexity while maintaining the motor braking function through the stator's inherent heat dissipation capabilities
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
Reduces manufacturing costs and simplifies the power tool's form factor by distributing braking resistance over a larger area, effectively dissipating heat without additional components.
Implementation Method 1
The motor braking coil and the braking switch are connected in parallel to the plurality of switching elements... the motor braking coil to brake the motor... dissipates heat through the stator core or airflow
Data Source
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AI summary
Method and power tool for braking a motor of the power tool. One embodiment provides a method for braking a motor of a power tool. The method includes operating, using a motor controller of the power tool, the motor in accordance with a user input. The method also includes detecting, using the motor controller, a braking event of the power tool and connecting, using a braking switch, a motor braking coil to the motor to brake the motor in response to detecting the braking event of the power tool. The method further includes cooling, using a component of the motor, the motor braking coil.