Nested Spring Vibration Damper for Hand Tools
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Solution Overview
Problem
Conventional vibration dampers for hand-held power tools require a significant installation space due to their overall length, which limits their compact design and effectiveness in reducing housing vibrations.
Innovation Solution
A vibration damper design where the spring is completely inside the oscillating absorber mass, reducing the overall length and minimizing stress on the spring, with a mirror-symmetrical absorber mass and housing arrangement that maintains symmetry and protects against contamination, allowing for efficient vibration damping with reduced spring stress and transverse vibration prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the spring is arranged outside the absorber mass with conventional vibration dampers, then the spring can be easily accessed and installed, but the overall length of the vibration absorber increases requiring larger installation space
Solution Approach 1:
The spring is nested completely inside the oscillating absorber mass, with the spring axis coinciding with the absorber mass axis. The spring is received in a recess of the absorber mass, creating a compact nested structure where the spring is contained within the absorber mass volume, thereby reducing the overall length of the vibration absorber assembly.
2Reliability
If two compression-preloaded coil springs are arranged axially on both sides of the absorber mass, then the vibration damping effect is sufficient, but the overall length of the vibration absorber becomes greater than the spring length requiring large installation space
Solution Approach 1:
Instead of arranging the spring outside the absorber mass as in conventional designs, the invention inverts the arrangement by placing the spring completely inside the absorber mass. This inversion allows the spring to be contained within the absorber mass volume, making the overall length of the vibration absorber essentially equal to the absorber mass length rather than being greater than the spring length.
3Reliability
If the spring performs full spring stroke during vibration, then the vibration damping is effective, but the spring experiences high stress and requires larger dimensions
Solution Approach 1:
The spring is nested within the absorber mass with its ends resting on opposite sides of the absorber mass. This nested arrangement allows the spring to perform approximately half the spring stroke of external springs while still providing effective vibration damping, thereby reducing the stress experienced by the spring and allowing for more compact spring dimensions.
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 design achieves lower resonance frequencies with a fixed absorber length and spring constant, reduces the overall length of the vibration absorber, and allows for easy retrofitting, while maintaining effective damping performance and protecting the oscillatable subsystem from contamination.
Implementation Method 1
an oscillating absorber mass 4 which is axially pressure-biased to the outer housing 2 via a spring 5
Implementation Method 2
the natural frequency of a passive vibration absorber is dimensioned close to the interference frequency to be damped
Implementation Method 3
a vibration damper for a hand-held power tool, in particular a rotary hammer, combination hammer or chipping hammer
Implementation Method 4
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
Figure 1~2
Figure 3~6
AI summary
A vibration damper for mounting on a housing of a hand-held power tool with a vibrating damper mass (4) which can be axially compressed against the housing (2) via at least one spring (5), wherein the spring (5) is arranged completely within the damper mass (4) with respect to its axial spring length.