Handheld Power Tool Anti-Kickback Control via Dynamic Holding Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hand-held power tools with anti-kickback systems face challenges in reliably triggering the protective function without risking user safety, as they struggle to accurately distinguish between holding force and other influences on the tool's movement, particularly due to varying applications and user movements.
Innovation Solution
A hand-held power tool equipped with a rotational movement sensor and a safety device that monitors the holding force by analyzing the amplitude of rotary movement within a specific frequency range (0.4 Hz to 4 Hz), adjusting the torque delivery based on the determined holding force, and using a brake mechanism to prevent excessive torque when a critical angle is approached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotational movement sensor and frequency-based holding force detection is implemented, then the reliability of protective function triggering is improved, but the device complexity increases
Solution Approach 1:
The safety device dynamically adapts the limit value for rotational movement based on the detected holding force. The system transitions from a static threshold approach to a dynamic one where the protective function's triggering parameters change in real-time according to user grip strength, improving reliability without requiring overly complex fixed-threshold systems
Solution Approach 2:
The system continuously monitors rotational movement through the sensor, detects holding force based on movement amplitude in the 0.4-4 Hz frequency range, and feeds this information back to adjust the limit value. This closed-loop feedback mechanism enables reliable protective function triggering while maintaining manageable system complexity through intelligent control algorithms
2Speed
If the safety device triggers based on rotational movement without considering holding force, then the response speed is improved, but the measurement precision of user intent deteriorates
Solution Approach 1:
The system performs preliminary detection of holding force characteristics by analyzing rotational movement amplitude in the specific frequency range (0.4-4 Hz) before making safety decisions. This preliminary characterization of user grip strength allows the system to subsequently adjust its response threshold, achieving both rapid response and precise measurement of user intent
Solution Approach 2:
The system changes the evaluation parameter from a fixed rotational movement threshold to a dynamic threshold based on detected holding force. By monitoring amplitude in the 0.4-4 Hz frequency range and adjusting the limit value accordingly, the system achieves precise measurement of user intent while maintaining fast response through efficient signal processing
3Ease of operation
If the limit value is fixed regardless of holding force, then the ease of operation is improved, but the adaptability to different users and applications deteriorates
Solution Approach 1:
The safety device performs self-adjustment by automatically detecting the user's holding force and adapting the limit value accordingly. The system serves itself by using its own sensor data to configure its safety parameters in real-time, eliminating the need for manual setup while achieving high adaptability to different users and application scenarios
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 effectively reduces the risk of user injury by accurately assessing the holding force and adapting the safety device's response, allowing for safer operation by adjusting the torque delivery based on user grip strength, thereby preventing tool rotation beyond a critical angle.
Implementation Method 1
A rotational movement sensor detects a rotational movement of the machine housing around the working axis. A monitor determines a holding force based on an amplitude of the rotary movement in a frequency range between 0.4 Hz and 4 Hz.
Data Source
Figure 1~2
AI summary
The invention relates to a handheld power tool (1) having a tool holder (2) for holding a tool on a working axis (11) and a motor (5) for rotationally driving the tool holder (2) about the working axis (11). The motor (5) is arranged in a power-tool housing (16), and a handle (9) is fastened to the power-tool housing (16) for guiding the handheld power tool (1) during operation. A rotational-motion sensor (15) senses a rotational motion of the power-tool housing (16) about the working axis (11). A monitor (19) determines a holding force on the basis of an amplitude of the rotational motion in a frequency range between 0.4 Hz and 4 Hz. A safety device (13) reduces a torque output to the tool holder (2) if the sensed rotational motion exceeds a limit value, wherein the limit value is set in accordance with the holding force.