Motor Control for Hydraulic Impact Power Tools
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Solution Overview
Problem
Electric power tools with hydraulic pressure generators that produce multiple impacts per revolution face issues with impact failure due to high impact frequency, especially under high load conditions, leading to reduced efficiency and usability.
Innovation Solution
Incorporating a motor control method that detects impact angle and electric current to determine impact failure, and adjusts the motor's rotation speed to prevent continued failure, ensuring efficient operation and smooth fastening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydraulic pressure generator is configured to generate multiple impacts per revolution, then the operation efficiency and smooth fastening performance are improved, but the impact frequency becomes excessively high under high load conditions causing impact failure
Solution Approach 1:
The patent applies dynamics by making the rotation speed of the hydraulic pressure generator variable rather than constant. The rotation speed is dynamically adjusted based on the detected impact frequency - when impact frequency exceeds a predetermined threshold, the rotation speed is reduced to prevent impact failure, and when impact frequency is within the normal range, the rotation speed is increased to improve operation efficiency. This dynamic adjustment resolves the contradiction between maintaining high productivity and preventing reliability issues.
Solution Approach 2:
The patent implements feedback control by detecting the impact frequency generated by the hydraulic pressure generator and using this information to control the rotation speed. The detection unit monitors impact frequency, and the control unit adjusts rotation speed based on this feedback. This closed-loop feedback mechanism ensures that the system automatically adapts to prevent impact failure while maintaining optimal operation efficiency, resolving the contradiction between high impact frequency benefits and reliability concerns.
2Productivity
If the rotation speed is increased to improve operation efficiency, then the impact frequency becomes high causing impact failure, but if the rotation speed is decreased to prevent impact failure, then the operation efficiency reduces
Solution Approach 1:
The system dynamically adjusts rotation speed based on real-time impact frequency detection. Rather than maintaining a fixed high or low rotation speed, the system optimizes rotation speed dynamically - increasing it when conditions allow for efficient operation and decreasing it when impact frequency approaches dangerous levels. This dynamic approach resolves the contradiction by allowing the system to operate at optimal efficiency most of the time while preventing impact failure when necessary.
Solution Approach 2:
The patent changes the operational parameter (rotation speed) based on detected conditions. When impact frequency exceeds the predetermined threshold, the rotation speed parameter is reduced; when impact frequency is within acceptable ranges, the rotation speed parameter is increased. This parameter adjustment strategy resolves the contradiction between operation efficiency and impact failure prevention by adaptively optimizing the rotation speed parameter according to actual operating conditions.
Data Source
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AI summary
An electric power tool (10) is provided with: a motor (14); a hydraulic pressure generator (18) driven by the motor (14) and configured to generate a plurality of impacts in one revolution thereof; an impact angle detector configured to detect an impact angle in one impact of the hydraulic pressure generator (18); an electric current detector (34) configured to detect an electric current applied to the motor (14); a determination unit configured to determine an impact failure based on the impact angle and the electric current detected by the impact angle detector and the electric current detector (34); and a rotation controller (46) configured to decrease a rotation speed of the motor (14) when the determination unit determines the impact failure.