Floating Inner Housing for Impact Tool Vibration Isolation
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Solution Overview
Problem
Power tools with impact mechanisms generate significant vibrations that can lead to premature failure and health issues, exceeding international vibration exposure limits and posing ergonomic and health risks.
Innovation Solution
A power tool design featuring an inner housing floatingly connected to an outer housing via pre-tensioned elastic elements, with axial supports and anti-rotation structures to absorb and decouple vibrations, reducing transmission to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-sided suspension of the cartridge assembly is used, then the structure is simple, but it does not effectively reduce axial vibration because contact force must be applied to push the cartridge assembly into its working point
Solution Approach 1:
The patent uses asymmetric pre-tensioning of elastic elements where the first elastic element has different pre-tension than the second elastic element. This creates an unbalanced force that automatically positions the inner housing at the effective working point without requiring external contact force, while enabling the inner housing to float and absorb axial vibrations effectively.
Solution Approach 2:
The patent introduces elastic elements as intermediary components between the inner housing and outer housing. These elastic elements with pre-tension act as mediators that both position the inner housing at the correct working point and provide vibration isolation, solving both the positioning and vibration reduction problems simultaneously.
2Stability of the object's composition
If the inner housing is rigidly fixed to the outer housing, then structural stability is high, but vibration is directly transmitted to the user's hands and arms
Solution Approach 1:
The patent replaces rigid fixed connections with flexible elastic elements that connect the inner housing to the outer housing. These elastic elements maintain structural stability while providing flexibility to absorb and reduce vibration transmission to the user, effectively resolving the contradiction between stability and vibration isolation.
3Ease of manufacture
If no pre-tension is applied to elastic elements, then assembly is simple, but the inner housing cannot be maintained at the effective working point without external contact force
Solution Approach 1:
The patent implements a self-positioning system where the pre-tensioned elastic elements automatically maintain the inner housing at the effective working point without requiring external contact force or complex adjustment mechanisms. The system serves itself by using the pre-tension forces to continuously position the inner housing correctly during operation.
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
Effectively reduces vibrations transmitted to the user, ensuring compliance with international vibration limits and enhancing user safety and tool durability.
Implementation Method 1
The inner housing and outer housing are elastically connected to each other in axial direction by at least two elastic elements pre-tensioned against each other... Vibration during the application would be absorbed by the floating of the inner sub-assembly
Implementation Method 2
The inner housing and outer housing are elastically connected to each other in axial direction by at least two elastic elements pre-tensioned against each other
Data Source
Figure 1~2
Figure 3~4b
Figure 5a~6
AI summary
A power tool with an impact mechanism in particular, an impact wrench or a hammer drill, comprising an outer housing and an inner housing at least partly surrounded by the outer housing; an motor installed in the inner housing, and an impact mechanism connected to the motor and fixedly mounted to the inner housing, to define an integrated inner sub-assembly comprising the motor and the impact mechanism; the inner housing and outer housing are elastically connected to each other in axial direction by at least two elastic elements pre-tensioned against each other, the inner housing floating received in the outer housing in axial direction, thereby reducing the vibration suffered by the user from the impact mechanism and motor of the power tool.