Electric Power Tool Reverse Stop Control for Fastener Loosening
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Solution Overview
Problem
Existing rotary impact tools often stop the motor before the fastener is sufficiently loosened, requiring users to manually unscrew the fastener or re-activate the tool, which is burdensome.
Innovation Solution
An electric power tool with a motor, output shaft, drive circuit, rotation controller, calculator, and deceleration controller that rotates the motor in reverse to loosen fasteners, with a determination value increasing over time based on the motor's speed parameter to ensure proper loosening before stopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the motor is stopped after a fixed time period in reverse direction, then the control is simple, but the fastener may not be sufficiently loosened requiring manual intervention
Solution Approach 1:
The patent changes the stopping criterion from a fixed time parameter to a variable determination value that increases at different rates based on motor speed. The calculator varies the rate of increase in the determination value according to the speed parameter, allowing the system to adapt the stopping timing to actual loosening progress rather than using a fixed time period
Solution Approach 2:
The system uses feedback from the motor speed parameter to adjust the determination value accumulation rate. By monitoring the speed parameter and varying the rate of increase accordingly, the system creates a feedback mechanism that ensures the motor stops at the appropriate moment when the fastener is properly loosened, rather than using a predetermined fixed time
2Reliability
If the motor runs for a longer time to ensure complete loosening, then the fastener is properly loosened, but the user burden increases and efficiency decreases
Solution Approach 1:
The system performs self-service by automatically determining when the fastener is sufficiently loosened through the calculator and deceleration controller. The motor controller autonomously monitors the determination value and speed parameter, then automatically decelerates and stops the motor at the optimal moment without requiring user judgment or manual intervention to check loosening status
Solution Approach 2:
The patent replaces the mechanical/manual checking and unscrewing process with an automated control system. Instead of the user needing to manually check if the fastener is loose and potentially re-activate the tool, the control system uses electronic monitoring of the determination value and speed parameter to automatically determine completion and initiate deceleration, substituting mechanical user actions with electronic control
Data Source
AI summary
An electric power tool in one aspect of the present disclosure includes a motor, an output shaft, a drive circuit, a rotation controller, a calculator, and a deceleration controller. The output shaft is configured to attach a tool bit thereto, and be rotated by the motor. The rotation controller rotates the output shaft to thereby loosen a fastener from a fastened material. The calculator increases a determination value in accordance with a lapse of time from a first timing, and varies a rate of increase in the determination value in accordance with a speed parameter. The deceleration controller decelerates or stops the motor based on the determination value having reached a threshold value.