Pneumatic Striker Shock Ring Damping
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Solution Overview
Problem
Existing pneumatic impact mechanisms in hand-held power tools experience increased vibrations and inefficiencies during exceptional operating conditions, such as empty blows, due to inadequate damping, leading to reduced durability and longer overall length.
Innovation Solution
A hand-held power tool with a pneumatic striking mechanism featuring a flying piston driven by an air spring, where the striker forms an outer radial collar supported by a shock ring with axial freedom, dissipating kinetic energy through frictional contact and internal material damping, and an axially limited, freely movable axial collar play length, allowing for efficient energy dissipation during empty strokes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional pneumatic impact mechanism is used, then the tool can deliver effective impact blows, but it generates increased vibrations and inefficiencies during empty blows
Solution Approach 1:
A shock ring is introduced as an intermediary component between the striker and the tool body. The shock ring absorbs and dissipates the kinetic energy from empty blows through frictional contact and internal material damping, preventing these vibrations from being transmitted to the tool body and handle, thereby reducing harmful vibrations while maintaining reliable impact performance
2Object-generated harmful factors
If damping elements are added to reduce vibrations, then vibrations are dampened, but the overall length of the tool increases
Solution Approach 1:
The shock ring is designed to fit concentrically around the striker, with the outer diameter of the shock ring being smaller than the inner diameter of the guide tube. This nested configuration allows the damping function to be integrated within the existing striker assembly without requiring additional axial space, thus dampening vibrations without increasing the overall length of the tool
3Device complexity
If the striker is constrained to move freely, then the mechanism is simple, but kinetic energy is not effectively dissipated during empty strokes
Solution Approach 1:
The shock ring is designed with specific mass parameters (mass ratio of shock ring to striker is at least 0.25) and dimensional parameters (axial play length, radial clearance) that optimize its energy dissipation performance. These parameter changes allow the shock ring to effectively absorb and dissipate kinetic energy during empty strokes through controlled frictional contact and material damping, while maintaining a relatively simple mechanism structure
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 dampens empty blows, shortens the striker's stroke path, and reduces vibrations, enhancing the tool's robustness and durability by ensuring stable impact operations and efficient energy transfer, ultimately leading to a more controlled striking mechanism.
Implementation Method 1
the kinetic energy of the striker is dissipated in the shock ring with axial play, in which frictional contact and internal material damping come into play
Implementation Method 2
the kinetic energy of the striker is dissipated in the shock ring with axial play, in which frictional contact and internal material damping come into play
Data Source
Figure 1
Figure 2
AI summary
A hand-held power tool that is at least partially impactive, with a pneumatic impact mechanism and a flying piston driven by an air spring, which strikes a striker (8) guided in a guide tube (6) and axially movable by means of two axial stops (9a, 9b), which forms an outer radial flange (11) that is radially encompassed on both sides by an inner radial flank (14) by a coaxially arranged external thrust ring (12) and is freely movable axially limited with respect to the outer radial flange (11), wherein the outer diameter of the thrust ring (12) is smaller than the leading inner diameter of the guide tube (6) and the mass ratio of the thrust ring (12) to the striker (8) is at least 0.25.