Impact Tool Motor Control for Low-Speed Reverse Rotation
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Solution Overview
Problem
Impact tools face challenges in maintaining normal operation at low impact frequencies due to torque fluctuations and potential reverse rotation of the electric motor when operating at low rotational speeds, especially when the torque of the electric motor is less than the tension of the elastic element.
Innovation Solution
A controller, such as a PI, PID, or LADRC controller, adjusts the duty cycle of the control signal to ensure the output torque of the electric motor exceeds the tension of the elastic element, preventing reverse rotation by maintaining or increasing the torque at low rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor operates at low rotational speed to achieve low impact frequency, then the impact frequency is reduced, but the torque fluctuates greatly and the motor may rotate reversely
Solution Approach 1:
The controller continuously monitors the rotational speed of the electric motor and dynamically adjusts the duty cycle of the control signal based on feedback. When the motor speed drops below a threshold, the controller increases the duty cycle to maintain torque above the elastic element tension, preventing reverse rotation and ensuring stable low-frequency impact operation.
Solution Approach 2:
The system changes the duty cycle parameter of the control signal in response to motor speed conditions. By adjusting this parameter, the output torque of the electric motor is controlled to remain greater than the tension of the elastic element even at low rotational speeds, thereby maintaining operational stability.
2Speed
If the electric motor operates continuously at low rotational speed, then low impact frequency is achieved, but the torque fluctuation causes the spring tension to exceed motor torque leading to reverse rotation
Solution Approach 1:
The control system dynamically adjusts the duty cycle based on real-time motor speed feedback. This dynamic adjustment ensures that the output torque adapts to changing operating conditions, maintaining sufficient torque to overcome elastic element tension even when operating at low rotational speeds for low impact frequency.
Solution Approach 2:
The controller uses feedback from rotational speed sensing to continuously monitor and adjust the duty cycle. This closed-loop control ensures that torque remains adequate to prevent reverse rotation caused by spring tension exceeding motor torque during continuous low-speed operation.
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 controller ensures the impact tool can operate consistently at low impact frequencies by preventing reverse rotation of the electric motor, ensuring stable operation even at low rotational speeds.
Implementation Method 1
an electric motor including a motor shaft capable of rotating about a first axis
Implementation Method 2
the impact assembly includes an elastic element
Data Source
AI summary
An impact tool includes an electric motor includes a motor shaft capable of rotating about a first axis; a battery pack powering at least the electric motor; an impact assembly drivable by the electric motor to provide an impact force; an output assembly including an output shaft for outputting power; where the impact assembly includes an elastic element; and a control circuit including at least a controller. The controller is configured to, in the case where an actual rotational speed of the electric motor is lower than a rotational speed threshold, control output torque of the electric motor to be greater than a tension of the elastic element.