Electric Power Tool Torque Control for Forward and Reverse
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Solution Overview
Problem
Conventional electric power tools require users to change the set torque value when switching from tightening to loosening screws, leading to poor usability due to the uniform torque setting across both rotation directions.
Innovation Solution
The electric power tool allows for separate torque setting for forward and reverse motor directions, enabling users to set a higher torque limit during reverse rotation, thereby facilitating easier loosening of screws without needing to adjust the torque setting each time the rotation direction is changed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a uniform torque setting is applied for both forward and reverse motor directions, then the device complexity is reduced and ease of operation is improved during tightening, but the adaptability deteriorates when loosening screws requiring higher torque
Solution Approach 1:
The patent applies dynamics by making the torque setting changeable based on motor rotation direction. The control unit dynamically adjusts the torque threshold according to whether the motor is rotating in the forward or reverse direction, allowing the system to adapt torque limits to different operational requirements without manual intervention.
Solution Approach 2:
The patent implements parameter changes by modifying the torque setting parameter based on the motor's rotation direction. The control unit detects the rotation direction and automatically adjusts the torque threshold parameter accordingly, enabling different torque levels for tightening (forward rotation) and loosening (reverse rotation) operations.
2Adaptability or versatility
If the set torque is changed between tightening and loosening operations, then the adaptability is improved for different tasks, but the ease of operation deteriorates due to requiring manual torque adjustment
Solution Approach 1:
The patent applies self-service by enabling the control unit to automatically adjust the torque setting based on the detected motor rotation direction. The system serves itself by autonomously selecting the appropriate torque threshold without requiring user intervention, thereby maintaining adaptability while improving ease of operation.
Solution Approach 2:
The patent implements feedback by using the detected motor rotation direction as input to automatically adjust the torque setting. The control unit continuously monitors the rotation direction and uses this feedback information to dynamically modify the torque threshold, creating a closed-loop system that adapts to operational requirements.
3Device complexity
If a single torque limit is used for both tightening and loosening, then the device complexity is minimized, but the manufacturing precision of torque control deteriorates for different operational requirements
Solution Approach 1:
The patent applies dynamics by implementing a dynamic torque limiting mechanism that adjusts the torque threshold based on motor rotation direction. This dynamic approach maintains relatively simple device architecture while achieving precise torque control for different operations through real-time parameter adjustment based on rotation detection.
Data Source
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AI summary
An electric power tool includes a motor (20) that rotary drives an output shaft; an operation unit (30) to input a drive command of the motor (20); a torque setting device (40) that sets an upper limit value of a rotational torque of the output shaft in accordance with a torque setting command; and a control device (40) that drives the motor (20) in one of a forward direction and a reverse direction in accordance with the drive command, and stops driving of the motor (20) when the rotational torque of the output shaft has reached the upper limit value set by the torque setting device (40) during driving of the motor (20). The torque setting device (40) is configured to set the upper limit value such that the upper limit value during driving of the motor (20) in the forward direction and the upper limit value during driving of the motor in the reverse direction are different.