Impact Rotary Tool PWM Torque Control
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Solution Overview
Problem
Impact rotary tools face challenges in maintaining torque accuracy due to varying battery voltage and task conditions, leading to potential excessive or insufficient tightening of fasteners.
Innovation Solution
An impact rotary tool equipped with a drive source, strike detector, rotation speed detector, rotation angle detector, torque calculator, and controller that performs PWM control to regulate strike force, maintaining torque accuracy by calculating and controlling tightening torque based on detected parameters and reference settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor operates at high speed to improve productivity, then the striking energy increases, but the torque accuracy deteriorates when battery voltage decreases
Solution Approach 1:
The controller dynamically adjusts the motor operation parameters based on detected battery voltage levels. When voltage decreases, the controller modifies the drive signal characteristics to maintain consistent striking energy and torque output, ensuring torque accuracy is preserved across varying battery conditions while maintaining high productivity
Solution Approach 2:
The system incorporates feedback mechanisms where the controller monitors battery voltage and adjusts motor operation accordingly. The controller receives feedback about voltage changes and automatically modifies striking parameters to maintain torque accuracy, preventing degradation in precision when battery voltage fluctuates
2Reliability
If the strike force is increased to ensure sufficient tightening, then the tightening reliability improves, but the risk of excessive tightening increases
Solution Approach 1:
The system dynamically controls strike force based on real-time detection of actual tightening conditions. The controller adjusts the magnitude of striking impulses according to the specific joint requirements and detected parameters, enabling sufficient tightening when needed while preventing excessive tightening through adaptive control
Solution Approach 2:
The impact rotary tool delivers striking energy in controlled periodic impulses rather than continuous force. The controller manages the timing and magnitude of these periodic strikes to achieve sufficient tightening through cumulative effect while maintaining control to prevent excessive tightening
3Manufacturing precision
If the motor operates at high torque to maintain strike force at low voltage, then the torque accuracy improves, but the productivity decreases
Solution Approach 1:
The controller changes motor operation parameters adaptively based on battery voltage conditions. At lower voltages, the system adjusts drive characteristics to maintain torque accuracy while accepting reduced striking speed, and vice versa at higher voltages, optimizing the balance between precision and productivity based on actual battery state
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
The solution ensures stable torque output across varying battery voltages and task conditions, preventing excessive or insufficient tightening, and extends tool usability by maintaining consistent strike force.
Implementation Method 1
The controller performs PWM control to limit strike force applied when the voltage of the battery pack is high and controls the drive source to maintain strike force even when the voltage of the battery pack is low
Data Source
AI summary
An impact rotary tool comprises a driving source that is supplied with power from a battery pack and that rotates a hammer via a drive shaft, and a controlling unit that controls the driving source. The controlling unit controls the driving source so that the striking force is limited by PWM control when the battery pack voltage is high and the striking force is maintained even when the battery pack voltage decreases.