Impact Mechanism Eccentric Assembly for High Radial and Axial Loads
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Solution Overview
Problem
Existing hand-held power tools with eccentric assemblies are complex, costly, and require high manufacturing effort due to the use of deep groove ball bearings, which have limited load-carrying capacity and necessitate complicated installation processes.
Innovation Solution
The eccentric wheel is mounted with a floating bearing on one side and a fixed bearing on the other side, allowing for easy assembly and high load capacity, using a cylindrical roller bearing for the floating bearing and a deep groove ball bearing for the fixed bearing, with a spacer sleeve and fixing element for secure installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If deep groove ball bearings are used to support the eccentric wheel, then axial forces can be supported, but the load carrying capacity is significantly lower for the same size and the structure becomes complicated and cost-intensive
Solution Approach 1:
The bearing support system is segmented into two distinct bearing types: deep groove ball bearings for axial force support and needle roller bearings for radial load support. This segmentation allows each bearing type to be optimized for its specific function, achieving high load carrying capacity while maintaining a manageable structural complexity through clear functional division.
2Force
If needle roller bearings are used instead of deep groove ball bearings, then load carrying capacity increases, but the machining effort and installation complexity increase significantly
Solution Approach 1:
The bearing system is segmented to use needle roller bearings specifically for radial load support where their high load carrying capacity is needed, while deep groove ball bearings handle axial forces. This functional segmentation allows each bearing type to be used only where necessary, optimizing performance while managing manufacturing complexity through clear role assignment.
Solution Approach 2:
The bearing arrangement is designed to support both radial and axial loads simultaneously through the combination of two bearing types working together. This multi-functional approach allows a single bearing system to handle multiple load directions and types, reducing the need for additional specialized components and simplifying the overall support structure.
3Reliability
If two fixed bearings are used to mount the eccentric wheel, then the wheel is firmly secured, but the installation requires pressing forces from both sides and special cost-intensive equipment
Solution Approach 1:
The bearing system is segmented into fixed and floating bearing positions, with the floating bearing allowing axial displacement. This segmentation enables the eccentric wheel to be securely mounted in the radial direction while permitting controlled axial movement, thereby achieving reliable securing without requiring complex bilateral pressing operations during installation.
4Reliability
If the eccentric assembly is designed to withstand high radial and axial loads, then durability is improved, but the assembly becomes heavier and more complex
Solution Approach 1:
The bearing support system employs local quality optimization by using deep groove ball bearings specifically at locations requiring axial force support and needle roller bearings where radial load support is critical. This localized bearing selection ensures high durability and load capacity are achieved precisely where needed, rather than uniformly throughout the entire assembly, thereby minimizing unnecessary weight and complexity.
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 results in a compact, lightweight, and cost-effective eccentric assembly that can withstand high radial and axial loads, simplifying manufacturing and installation while maintaining durability.
Implementation Method 1
The floating bearing is designed as a cylindrical roller bearing
Implementation Method 2
the fixed bearing is designed as a deep groove ball bearing
Data Source
AI summary
A hand-held power tool, in particular a demolition hammer, with an impact mechanism assembly includes an electric motor, an eccentric assembly, and an impact pin oscillating linearly along an impact mechanism axis. The eccentric assembly includes an eccentric wheel mounted in an impact mechanism carrier of the impact mechanism assembly, an eccentric wheel rotating about an eccentric axis, and a connecting rod driven by the eccentric wheel. The electric motor has a motor shaft along a motor axis which drives the impact piston by way of the eccentric wheel and the connecting rod. The eccentric wheel has an eccentric hub formed on one side, which is mounted along the eccentric axis on a side of the eccentric wheel facing away from the connecting rod proximally with a floating bearing and distally with a fixed bearing in the impact mechanism carrier.