Impact Tool Control With Periodic Motor Shutdown for Thin Screws
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Solution Overview
Problem
Existing impact tools, such as impact screwdrivers, often operate at excessively high speeds when loosening or tightening thin screws, leading to potential damage to the operation surface due to excessive torque and speed.
Innovation Solution
The impact tool incorporates an electric motor with a drive shaft, an output shaft for torque transmission, an impact mechanism with a hammer anvil connected to the output shaft, and a controller that manages the motor's operation. In low-speed mode, the controller periodically shuts down the motor after a preset number of impacts and a corresponding preset period, adjusting the duty cycle based on the trigger stroke and battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the impact tool operates at high speed to increase productivity, then the screwing efficiency is improved, but the operation surface will be damaged due to excessively high speed and torque
Solution Approach 1:
The controller implements periodic shutdown of the electric motor after a preset number of impacts, creating cyclic operation patterns. This periodic action allows the impact mechanism to deliver controlled impact forces while preventing continuous high-speed operation that would damage the operation surface, thus resolving the contradiction between productivity and surface protection
2Productivity
If the impact tool operates continuously to complete screwing tasks, then the productivity is improved, but the operation surface will be damaged by excessively fast impact
Solution Approach 1:
The controller periodically shuts down the electric motor after detecting a preset number of impacts, transforming continuous operation into periodic cycles. This enables the tool to complete screwing tasks efficiently while preventing excessive continuous impact that would damage the operation surface
Solution Approach 2:
The controller detects the impact frequency and motor operating state, then adjusts the motor shutdown timing based on this feedback. This closed-loop control ensures that impacts remain within safe limits while maintaining productivity, preventing operation surface damage from excessive impact frequency
Data Source
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Figure 3a~3c
AI summary
An impact tool includes: an impact mechanism, where the impact mechanism includes an impact block driven by a drive shaft and a hammer anvil receiving an impact from the impact block, and the hammer anvil is connected to an output shaft; and a controller configured to control an electric motor. The controller is configured to, when the impact tool is in a low-speed mode and it is detected that the impact mechanism applies an impact force to the output shaft, perform the operations periodically: determining that the impact mechanism impacts a preset number of times and controlling the electric motor to shut down for a preset period and then restart.