Power Tool Motor Control for Efficient Screw Removal
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Solution Overview
Problem
Existing electric power tools lack an efficient method for automatically releasing screws, often consuming excessive energy and not accurately adapting to the connection force between the screw and its counterpart, especially when powered by batteries.
Innovation Solution
The method involves measuring power consumption over time to determine a third power limit, reducing motor power by at least 30% when below this limit, and using sensors to monitor and control the release process, ensuring precise adaptation to the screw's connection force and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor continuously operates at high power to ensure reliable screw release, then the reliability of screw release is improved, but the energy consumption increases significantly
Solution Approach 1:
The electric motor operates in multiple power segments (first segment with first power limit, second segment with second power limit, third segment with third power limit) rather than maintaining constant high power. The control device dynamically adjusts the power output based on the detected connection force, switching between segments to balance reliability and energy efficiency.
Solution Approach 2:
The control device detects the connection force between the screw element and counterpart in real-time and uses this feedback to determine the appropriate power segment. The third power limit is determined based on measured power values from the second segment, creating a closed-loop control system that adapts power output to actual loading conditions.
2Reliability
If the electric motor uses a fixed high power limit to ensure complete screw release, then the screw release completeness is improved, but the load on the screw element increases causing potential damage
Solution Approach 1:
The system uses variable power limits across different segments instead of a fixed high power limit. The third power limit, determined from measurements in the second segment, allows the system to adapt the release force to the actual connection strength, ensuring complete release without applying excessive load that could damage the screw element.
3Device complexity
If the electric motor operates without power segmentation to simplify control, then the device complexity is reduced, but the adaptability to different connection forces deteriorates
Solution Approach 1:
The control method divides the power output into distinct segments (first segment with first power limit, second segment with second power limit, third segment with third power limit). This segmentation allows the system to adapt to different connection force levels while maintaining relatively simple control logic for switching between segments based on detected conditions.
4Loss of energy
If the electric motor reduces power below the third power limit to save energy, then the energy efficiency is improved, but the risk of incomplete screw release increases
Solution Approach 1:
The control device continuously monitors the connection force and compares it against the third power limit, which is determined from measurements in the second segment. This feedback mechanism ensures that power is reduced to save energy only when the connection force is sufficiently low, maintaining screw release completeness while improving energy efficiency.
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
This approach enables improved and energy-efficient screw release, reducing the load on the screw and conserving energy, particularly in battery-powered tools, while preventing complete release to avoid over-tightening.
Implementation Method 1
an electric motor for rotating a rotation element
Data Source
AI summary
A method for operating a power tool having a motor for removing a screw from a counterpart is disclosed. A rotary element connects to the power tool to the screw. In a first section, if a first power limit is exceeded for a first duration, a change is made to a second section in which a temporal profile of the power is recorded for a second duration. A change is made into a third region when the power is above a second power limit for the second duration and a temporal fluctuation of the power is within a fluctuation value. A third power limit is determined based on power recorded in the second section. A change is made from the third section into a fourth section when the power drops below the third power limit within a third duration. In the fourth section, the power of the motor is reduced.