Hand-Held Power Tool Vibration Absorber Calibration
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Solution Overview
Problem
Hand-held power tools, such as hammer drills, experience significant vibrations during operation due to the impact mechanism, which can lead to user discomfort and reduced efficiency, as existing vibration absorbers do not effectively adapt to varying impact frequencies and maintain optimal damping performance over time.
Innovation Solution
A control method for a hand-held power tool that includes a vibration absorber with a movable oscillator and springs, which is calibrated using an acceleration sensor to adjust the impact rate to match the natural frequency of the absorber, ensuring optimal vibration reduction by synchronizing the impact frequency with the absorber's natural frequency, and a damping controller that modifies the motor speed to maintain this synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a vibration absorber with a freely suspended oscillator is used to damp vibrations, then vibration reduction is achieved, but the absorber cannot adapt to varying impact frequencies and maintains optimal damping performance over time
Solution Approach 1:
The patent implements a dynamic calibration process where the impact rate is adjusted during operation to match the natural frequency of the vibration absorber. The control method varies the impact rate within a range (e.g., 90%-110% of setpoint) to detect and adapt to changes in the absorber's natural frequency, enabling the system to maintain optimal vibration damping performance under varying operating conditions.
Solution Approach 2:
The patent employs feedback mechanisms using acceleration sensors to detect vibrations and a control system that monitors the relationship between impact rate and vibration amplitude. Based on this feedback, the system automatically adjusts the impact rate to maintain synchronization with the vibration absorber's natural frequency, ensuring continuous optimal damping performance.
2Productivity
If the impact rate is increased to improve drilling efficiency, then productivity increases, but vibration amplitude increases reducing user comfort
Solution Approach 1:
The patent utilizes mechanical vibration principles by tuning the vibration absorber's natural frequency to match the impact frequency of the hammer mechanism. This resonance-based approach allows the absorber to effectively counteract harmful vibrations even at high impact rates, enabling high productivity while maintaining user comfort through optimized frequency synchronization.
3Stability of the object's composition
If the vibration absorber operates at a fixed natural frequency, then the damping performance is stable, but it cannot maintain optimal performance when the absorber's natural frequency changes over time
Solution Approach 1:
The patent implements continuous feedback monitoring through acceleration sensors that detect changes in the vibration absorber's natural frequency. The control system processes this feedback and dynamically adjusts the impact rate to maintain synchronization, ensuring that optimal damping performance is maintained even as the absorber's natural frequency drifts due to wear, temperature changes, or other operational factors.
Solution Approach 2:
The system performs self-calibration by automatically detecting and adapting to changes in its own characteristics. Through the calibration process, the system independently identifies shifts in the vibration absorber's natural frequency and adjusts operating parameters accordingly, maintaining optimal performance without external intervention.
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 solution significantly reduces vibrations transferred to the handle, ensuring maximum impact power while minimizing user discomfort and maintaining efficient operation by continuously adapting to changes in the absorber's natural frequency, thereby enhancing user experience and tool performance.
Implementation Method 1
a vibration absorber with a movable oscillator and springs, which is calibrated using an acceleration sensor to adjust the impact rate to match the natural frequency of the absorber, ensuring optimal vibration reduction by synchronizing the impact frequency with the absorber's natural frequency
Implementation Method 2
U.S. Pat. No. 8,434,565 B2 describes a hammer drill whose hammer mechanism drives a bit at an impact frequency into a substrate. The vibrations which occur at the impact frequency are damped by a vibration absorber.
Implementation Method 3
detecting an acceleration with the aid of the acceleration sensor, ascertaining a minimum of the acceleration by varying the impact rate in a range between 90% and 110% of the setpoint value
Data Source
AI summary
The hand-held power tool has a tool holder (2) for holding a tool (4) along a working axis (12). A hammer mechanism (6) has a striker (15) that is moved periodically along the working axis at an impact rate. A drive control (18) of the hammer mechanism (6) sets the impact rate to a set point value. A vibration absorber (19) has an oscillator (21) that moves along the working axis (12) about a resting position and one or multiple springs (20) that drive the oscillator (21) back into the resting position. A calibration phase comprises the following steps: detection of an acceleration using the acceleration sensor (24); determination of a minimum of the acceleration by varying the impact rate in a range of between 90% and 110% of the set point value; and adjusting the set point to the impact rate associated with the ascertained minimum.