Hand-held Power Tool Vibration Damping via Phase Synchronization
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Solution Overview
Problem
Existing hand-held power tools with vibration absorbers face challenges in effectively damping periodic vibrations, particularly in maintaining a phase difference between the hammer mechanism and the vibration absorber to minimize user discomfort and tool instability during operation.
Innovation Solution
A control method for a hand-held power tool that includes a vibration absorber with an oscillator and springs, where a damping controller adjusts the impact rate of the hammer mechanism to synchronize the phases of the hammer mechanism and the vibration absorber, ensuring a phase difference less than a threshold value, thereby reducing vibrations transferred to the handle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a vibration absorber with an oscillator and springs is used to damp periodic vibrations, then vibrations transferred to the user are reduced, but phase synchronization between the hammer mechanism and vibration absorber becomes difficult to maintain, leading to residual vibrations
Solution Approach 1:
The patent employs sensors to detect the phase of the hammer mechanism and the phase of the vibration absorber oscillator. A control unit processes these phase signals and adjusts the drive signal to the hammer mechanism accordingly, creating a closed-loop feedback system that maintains optimal phase synchronization and minimizes residual vibrations.
Solution Approach 2:
The system dynamically adjusts the drive characteristics of the hammer mechanism based on real-time phase detection. The control unit modifies the phase and amplitude of the drive signal adaptively, allowing the vibration absorber to effectively counteract vibrations across varying operating conditions while maintaining synchronization.
2Productivity
If the impact rate of the hammer mechanism is increased to improve productivity, then drilling efficiency increases, but vibration amplitude increases, making vibration damping more difficult
Solution Approach 1:
The patent utilizes the principle of vibration cancellation by introducing an oscillator in the vibration absorber that vibrates at the same frequency as the hammer mechanism. The oscillator is designed to move in opposition to the hammer's vibrations, creating destructive interference that reduces net vibration amplitude even at high impact rates.
Solution Approach 2:
The system changes the phase and frequency parameters of the vibration absorber oscillator to match the hammer mechanism's operating conditions. By dynamically adjusting these parameters, the system maintains effective vibration damping across a wide range of impact rates, allowing high productivity without excessive vibration.
3Object-affected harmful factors
If the mass of the oscillator and resilience of the springs are adapted to the impact frequency, then vibration damping is optimized, but the system becomes more complex and harder to adjust to varying frequencies
Solution Approach 1:
Instead of using fixed mass and spring constants, the patent employs a control system that dynamically adjusts the effective stiffness and mass characteristics of the vibration absorber. The control unit modifies the drive signal parameters to adapt the oscillator's natural frequency to match varying impact frequencies, eliminating the need for physical reconfiguration.
Solution Approach 2:
The vibration absorber system is designed to effectively damp vibrations across multiple frequency ranges through electronic control. The same oscillator and spring assembly can be adapted to different impact frequencies by adjusting the drive signal, making the system universally applicable to various drilling conditions without requiring frequency-specific hardware configurations.
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 effectively reduces the amplitude of vibrations felt by the user, enhancing tool stability and comfort by optimizing the phase difference between the hammer mechanism and the vibration absorber, achieving optimal damping through synchronization of the impact frequency with the natural frequency of the absorber.
Implementation Method 1
one or multiple spring(s) which drive(s) the oscillator back into the resting position
Implementation Method 2
a vibration absorber for damping periodic vibrations
Data Source
AI summary
A hand-held power tool has a tool holder for holding a tool along a working axis. A hammer mechanism has a striker that is moved periodically at an impact rate along the working axis between a turning point in the proximity of the tool and a turning point remote from the tool. A drive control of the hammer mechanism sets the impact rate to a set point value. A vibration absorber has an oscillator that moves along the working axis about a resting position and one or multiple springs that drive the oscillator back into the resting position. A first sensor is used to determine a phase of the motion of the striker. A sensor is used to determine a first phase of a compression point of the hammer mechanism. Another sensor is used to determine a second phase of a turning point in the proximity of the tool, of the hammer mechanism. A damping controller adapts the set point value in such a way that a phase difference between the first phase and the second phase is less than a threshold value.