Switchable Vibration Damper for Hand-Held Power Tools
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Passive vibration dampers in hand-held power tools have a narrow frequency band, requiring precise matching of the natural frequency to the interference frequency, which is challenging due to varying percussion frequencies depending on the operating mode selected by the user.
Innovation Solution
A vibration absorber with a switchable, variable impact frequency is achieved by adding an additional spring that can be connected to the housing via user-selectable switching means, allowing the natural resonance frequency to be adjusted to match the changed impact frequency, while maintaining symmetry to prevent bending or transverse vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a passive vibration damper with fixed spring constant is used, then the natural frequency can be matched to a specific interference frequency, but it cannot adapt to varying percussion frequencies across different operating modes
Solution Approach 1:
The vibration damper transitions from a static configuration with fixed spring constants to a dynamic configuration where the spring constant can be changed during operation. The device includes switching means that allow the user to select between different spring constants (k1, k2, ..., kn) mounted on the absorber mass, enabling the natural frequency to be adjusted to match different percussion frequencies across operating modes.
Solution Approach 2:
The invention changes the physical parameter of spring constant from a fixed value to a switchable set of discrete values. By providing multiple springs with different spring constants and means to switch between them, the system can adjust its natural frequency parameter to match varying interference frequencies, thereby resolving the contradiction between adaptability and complexity.
2Adaptability or versatility
If multiple springs with different spring constants are provided to match different percussion frequencies, then adaptability to varying operating modes is improved, but the device complexity and space requirements increase
Solution Approach 1:
Multiple springs with different spring constants are arranged concentrically around the absorber mass, with each spring nested within the structure of the previous one. This nested arrangement allows multiple functional elements to occupy minimal space while remaining accessible to the switching mechanism, thereby reducing the overall volume required for the vibration damper while maintaining adaptability across operating modes.
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 dampens the outer housing vibrations across different operating modes by allowing the natural frequency of the vibration absorber to be dynamically adjusted, ensuring optimal damping regardless of the user-selected mode.
Implementation Method 1
an absorber mass (3) which can be oscillated along an impact axis (A) and which is axially pressure-preloaded towards a housing (5) via at least one spring (4)
Implementation Method 2
the natural frequency of a passive vibration absorber is dimensioned close to the interference frequency to be damped
Implementation Method 3
the absorber mass (3) can be connected in a switchable manner, at least via an additional spring (9), to the housing (5) in an axially pressure-preloaded manner
Implementation Method 4
The additional spring is dimensioned in such a way that the changed natural resonance frequency corresponds to the changed impact frequency
Implementation Method 5
passive vibration dampers of this type are used in percussive hand-held power tools to reduce housing vibrations
Implementation Method 6
The abstract damper in particular is often not realized as a concrete component and is nevertheless effective due to the friction and flow losses that practically always occur
Data Source
AI summary
The damper (1) has a damping mass (3), and a spring (4) for axially and compressively preloading the mass against a power tool housing (5). A spring (9) is provided for axially and compressively preloading the mass against the housing. A user-operated switching element (8) is displaceable between a position in which the mass is axially and compressively preloaded against the housing by the spring (4) and another position in which the element connects the mass with the spring (9) so that the mass is preloaded against the housing by both the springs.