Power Tool Restart Delay Control for Anti-Sparking Motors
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Solution Overview
Problem
Existing power tools with AC brushed motors experience sparking issues and safety risks due to the use of Hall components and magnetic rings, which occupy internal space, increase failure risk, and can be demagnetized or damaged.
Innovation Solution
An anti-sparking method using a power module, motor driving module, and MCU module to control motor power supply based on operation states and delay times, eliminating the need for Hall components and magnetic rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Hall component and magnetic ring are added to detect motor rotation state, then motor reversing can be prevented and sparking can be avoided, but internal space of power tool is occupied
Solution Approach 1:
The patent extracts and removes the Hall component and magnetic ring from the system. Instead of using these physical detection components, the invention uses the existing brushless motor's back-EMF signal to detect rotation state, thereby eliminating the need for separate detection components and freeing up internal space.
Solution Approach 2:
The patent makes the brushless motor serve multiple functions: it not only drives the tool but also provides rotation state detection through its back-EMF signal. This multi-functionality eliminates the need for separate detection components like Hall sensors and magnetic rings.
2Measurement precision
If magnetic ring and Hall element are used for motor detection, then motor rotation state can be detected, but magnetic ring may be demagnetized and Hall element may be damaged
Solution Approach 1:
The patent extracts and eliminates the magnetic ring and Hall element from the detection system. By using the brushless motor's back-EMF signal, the invention removes the vulnerable magnetic components that could be demagnetized or damaged, thereby improving component durability while maintaining detection precision.
Data Source
AI summary
An anti-sparking method for a power tool includes the following steps: (1) turning on a controlling switch, which causes a motor to rotate, and a MCU module to record a first operation state of the motor; (2) turning off the controlling switch which causes the motor begin to stop rotating and the MCU module to record a time duration from a time point of the motor being begun to stop rotating to a time point of the motor completely stopped rotating as t1; (3) turning on the controlling switch again, which causes the MCU module to record a second operation state of the motor. When the first and second operation states are different, the MCU module controls the power module to supply power to the motor driving module after a delay time duration, which is longer than t1. A control device and a computer readable storage medium are also provided.