Power Tool Reverse Braking Control for Precise Fastener Release
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Solution Overview
Problem
Existing power tools struggle to accurately control motor shutdown during the reverse operation of fasteners, especially when dealing with fasteners of different sizes and varying working conditions, leading to potential over-loosening or under-loosening issues due to high motor speeds.
Innovation Solution
A power tool equipped with a control unit that detects operation parameters and adjusts motor speed through variable duty cycles to ensure controlled shutdown, using a parameter detection unit and speed detection unit to maintain the motor at a preset speed, allowing for precise control based on actual conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the motor supply current is turned off when current value is continuously less than preset current value for preset period of time, then the motor shutdown control is automated, but the fastener may be too loose or not loose enough after reverse shutdown due to high motor speed
Solution Approach 1:
The patent applies dynamics by making the motor shutdown process adjustable and adaptive. The control unit can dynamically adjust the shutdown timing based on detected motor parameters (current, speed, torque), allowing the system to adapt to different fastener sizes and working conditions. This resolves the contradiction by maintaining automation while improving precision through dynamic parameter adjustment.
Solution Approach 2:
The patent changes operational parameters (motor current threshold, speed threshold, time delay) to optimize both automation and precision. By adjusting these parameters based on the specific application, the system achieves accurate fastener loosening control while maintaining automated operation. The control unit modifies shutdown criteria parameters to match different fastener requirements.
2Ease of operation
If the user manually loosens the switch to cut off motor current, then the user has direct control over motor shutdown, but the user must make judgment calls that are difficult when fasteners have different sizes and working conditions vary
Solution Approach 1:
The patent applies self-service by enabling the control unit to automatically detect motor parameters and determine the optimal shutdown timing without user intervention. The system monitors current, speed, and torque parameters autonomously and executes shutdown decisions based on pre-set criteria, eliminating the need for users to manually judge when to stop the motor while maintaining ease of operation through automatic adaptation to different fasteners.
Solution Approach 2:
The patent implements feedback mechanisms where the control unit continuously monitors motor operation parameters (current, speed, torque) and uses this feedback to adjust shutdown timing. This closed-loop control provides adaptability to different fastener sizes and conditions while maintaining ease of operation, as the system automatically responds to real-time parameter changes.
3Productivity
If the motor runs at high speed during reverse operation, then the productivity is high, but it becomes difficult to control the motor shutdown precisely for different fastener requirements
Solution Approach 1:
The patent applies preliminary action by pre-setting shutdown criteria parameters (current thresholds, time delays, speed thresholds) before operation begins. The control unit uses these pre-configured parameters to automatically determine shutdown timing based on real-time motor parameter detection, enabling high-speed operation while maintaining precise shutdown control for different fastener requirements.
Data Source
AI summary
The example discloses a power tool and a control method. The power tool includes a driving unit and a control unit. The control unit connect with a mode selection device, a parameter detection unit, and a speed detection unit, and the mode selection device is provided with at least one gear position of releasing a fastener. If the parameters of the motor operation are continuously smaller than the preset motor parameter within first preset time, the control unit outputs slow braking signals with the duty cycle less than 100% to the driving unit so as to control the motor to be braked slowly and lasts for second preset time, and the control unit receives the motor rotating speed detected by the rotating speed detection unit and controls the motor to be kept at the preset rotating speed.