Electric Bush Cutter Electronic Braking and Blade Detection
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Solution Overview
Problem
Electric bush cutters lack an effective brake mechanism, leading to unsafe sudden stops and increased motor and battery usage, and have a rigid design that does not allow for compact storage.
Innovation Solution
Incorporating an electronic brake system controlled by a microcomputer that applies braking by short-circuiting the motor's terminals and using a detection unit to ensure the cutting blade is fully extended before starting, and only restarting when the blade is fully extended and the trigger is reactivated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brake device is added to the electric bush cutter, then the stopping performance is improved, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical brake device with an electronic brake system that uses electrical switching elements (MOSFETs or IGBTs) to short-circuit the motor terminals. This substitution eliminates mechanical wear and complexity while achieving reliable stopping performance through electronic control.
Solution Approach 2:
The control unit acts as an intermediary between the trigger switch and the switching elements, processing the stop signal and controlling the timing of the electronic brake activation. This intermediary control ensures coordinated operation and prevents motor damage during stopping.
2Volume of moving object
If the rod is designed to be extendable and retractable for compact storage, then the storage efficiency is improved, but the reliability of operation decreases
Solution Approach 1:
The patent incorporates a detection unit that provides feedback on the rod's extension state to the control unit. This feedback mechanism ensures the motor cannot operate unless the rod is fully extended, preventing operational accidents while maintaining compact storage capability through retraction.
Solution Approach 2:
The system performs a preliminary check of the rod extension state before allowing motor operation. The detection unit verifies the rod is fully extended, and only then does the control unit permit motor startup, ensuring safety before operational action begins.
3Productivity
If sudden stopping of the motor is implemented, then the productivity is improved, but the motor life decreases
Solution Approach 1:
The control unit performs preliminary assessment of motor state before activating the electronic brake. It checks rotation direction and prepares the switching elements in advance, enabling rapid stopping while controlling the rate of change to protect the motor from sudden mechanical shock.
Solution Approach 2:
The system dynamically adjusts the braking parameters by controlling the timing and sequence of switching element activation. By varying the electrical parameters during the stopping process, the system achieves fast response while limiting stress on the motor, thereby extending motor life.
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
This solution provides safe and controlled stopping of the motor, reduces motor and battery wear, and allows for a compact, adjustable design that enhances user safety and storage efficiency.
Implementation Method 1
a switching element configured to perform short-circuiting between terminals of the motor to apply electronic braking
Data Source
AI summary
An electric working machine including: a motor; a driving unit configured to be driven by the motor; a trigger switch configured to allow rotation of the motor; a power supply unit configured to supply electric power to the motor; and a control unit configured to control rotation of the motor, characterized in that: the electric working machine further comprises a switching element configured to perform short-circuiting between terminals of the motor to apply electronic braking, wherein the control unit is configured to perform adjustment of the braking by controlling the switching element when stopping the motor.