Impact Tool Load-Based Pulse Control
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Solution Overview
Problem
Conventional impact tools with brushless DC motors face issues such as high power consumption, excessive torque leading to screw coming-out, difficulty in controlling torque, and inefficiencies in drill mode operation due to complex mechanisms and lack of load-based power adjustment, resulting in discomfort and inefficiency during fastening tasks.
Innovation Solution
An impact tool with an electronic pulse driver that controls motor pulses based on load state, using a control unit to adjust driving pulses according to changes in motor current and rotation number, allowing for intermittent driving modes and precise torque control, thereby reducing power consumption and preventing excessive torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If constant driving electric power is supplied to the motor during striking, then high fastening torque is achieved, but excessive power consumption occurs and screw coming-out phenomenon happens
Solution Approach 1:
The patent applies dynamics by making the driving electric power variable rather than constant. The control unit adjusts the driving electric power supplied to the motor based on the load state during screw fastening operations. When the screw is fully fastened, the power is reduced to prevent excessive torque and coming-out phenomenon, while maintaining high power during the fastening process to achieve strong fastening torque.
Solution Approach 2:
The patent implements feedback control where the control unit monitors the load state during screw fastening and adjusts the driving electric power accordingly. The system detects when the screw has been fully fastened and automatically reduces the power supply to prevent over-torquing and coming-out, creating a closed-loop control system that optimizes both fastening torque and power consumption.
2Adaptability or versatility
If a retreat operation control mechanism is added to enable drill mode, then operational versatility is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent achieves multi-functionality by enabling the impact tool to operate in both impact mode and drill mode using the existing motor and control unit. The control unit switches between different operating modes based on user input, allowing the same device to perform both screw fastening and drilling operations without requiring separate dedicated mechanisms for each function.
Solution Approach 2:
The patent extracts the retreat operation control functionality from a separate mechanical mechanism and integrates it into the electronic control system. By using the control unit to manage motor power and rotation, the system achieves drill mode capability without adding complex mechanical retreat mechanisms, thereby reducing overall device complexity.
3Measurement precision
If clutch mechanism is added to interrupt power transmission at given torque, then torque control precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces the mechanical clutch mechanism with an electronic control system. The control unit monitors the load state and motor current to detect when the screw has been fully fastened, then automatically reduces or interrupts power transmission electronically. This substitution eliminates the need for mechanical clutch components while achieving precise torque control through electronic means.
Solution Approach 2:
The patent implements feedback control where the control unit continuously monitors motor current and load state to detect when the screw has reached full fastening torque. Based on this feedback, the system automatically adjusts power transmission by reducing or interrupting motor power, achieving precise torque control without requiring mechanical clutch mechanisms.
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 enables efficient power use, precise torque control, and comfortable operation by adjusting motor pulses based on load, preventing screw coming-out and ensuring accurate fastening, while simplifying the control unit configuration and reducing costs.
Implementation Method 1
Coils (windings) are used on the stator side, magnets (permanent magnets) are used on the rotor side, and a rotor is rotated as the electric power driven by an inverter circuit is sequentially applied to predetermined coils
Implementation Method 2
An inner peripheral surface of the hammer includes an inverted V-shaped (substantially triangular) cam groove. A V-shaped cam groove is axially provided in an outer peripheral surface of the spindle, and the hammer rotates via balls (steel balls) inserted between the cam groove and the inner peripheral cam groove of the hammer
Data Source
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AI summary
According to an aspect of the present invention, there is provided an impact tool including: a motor drivable in an intermittent driving mode; a hammer connected to the motor; an anvil to be struck by the hammer to thereby rotate/strike a tip tool; and a control unit that controls a rotation of the motor by switching a driving pulse supplied to the motor in accordance with a load applied onto the tip tool.