Impact Power Tool Torque Control via Strike Speed Feedback
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Solution Overview
Problem
Impact power tools face challenges in maintaining stable tightening torque as the voltage of the driving power source decreases, leading to reduced torque management in applications requiring precise control, such as in factories.
Innovation Solution
The impact power tool incorporates a strike detection unit, rotation angle detection unit, and a control unit that adjusts the number of strikes based on the detected striking speed to maintain consistent torque, correcting the strike number to compensate for reduced power source voltage and preventing insufficient tightening torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the impact power tool operates at high speed with increased torque, then productivity is improved, but the tightening torque becomes unstable when the power source voltage drops
Solution Approach 1:
The control unit continuously monitors the striking speed detected by the striking speed detection unit and uses this feedback to dynamically adjust the predetermined strike number. When the striking speed decreases due to voltage drop, the system automatically increases the strike number to compensate, maintaining stable tightening torque throughout the operation.
Solution Approach 2:
The patent transforms the static predetermined strike number into a dynamic parameter that automatically adjusts based on real-time striking speed conditions. The control unit modifies the strike number in response to changing voltage and striking speed, making the system adaptive to power source degradation during continuous operation.
2Device complexity
If the shutoff is performed by using only the number of strikes, then the device complexity is reduced, but the tightening torque management becomes impossible in factories requiring precise control
Solution Approach 1:
The system performs preliminary detection of striking speed before the tightening process concludes, and proactively adjusts the predetermined strike number based on this early information. This allows the simple strike-counting mechanism to be enhanced with speed-based correction without adding complex control systems.
Solution Approach 2:
The patent changes the parameter used for shutoff control from a fixed strike number to a variable strike number that is corrected based on striking speed. This parameter change enables precise torque management while maintaining the simplicity of the strike-counting approach, as the correction is calculated automatically from detected speed data.
3Loss of energy
If the voltage of the battery is reduced due to continuous operation, then the loss of energy is natural, but the tightening torque is gradually reduced making torque management impossible
Solution Approach 1:
The striking speed detection unit provides continuous feedback on the impact energy delivered to the bolt. When voltage reduction causes striking speed to decrease, the control unit detects this through the striking speed calculation and compensates by increasing the predetermined strike number, ensuring consistent torque despite energy loss.
Solution Approach 2:
The system dynamically changes the strike number parameter in response to detected striking speed variations caused by battery voltage reduction. This automatic parameter adjustment compensates for energy loss and maintains reliable torque application throughout the battery's discharge cycle.
Data Source
AI summary
An impact power tool includes an impact mechanism for applying a striking impact to an output shaft by using an output power of a motor. A strike detection unit detects the striking impact applied by the impact mechanism to obtain a striking timing and a striking speed detection unit calculates a striking speed from the striking timing obtained by the strike detection unit and a rotation angle of the motor obtained by a rotation angle detection unit. A control unit counts the number of striking impact detected by the strike detection unit and stops the motor if the number of striking impact reaches a predetermined strike number. The control unit is designed to correct the predetermined strike number when the striking speed obtained in the striking speed detection unit is equal to or lower than a specified striking speed.