Power Tool Vibration Reduction via Opposite Connecting Rod Orientation
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Solution Overview
Problem
Hand-held power tools like hedge trimmers experience significant vibrations during operation, leading to stress on operators and reduced tool service life due to the transmission of forces generated by oscillating cutter bar masses, particularly at higher engine speeds.
Innovation Solution
The pivot joint on the second connecting rod is positioned on the end facing away from the tool members, and the connecting rods are oriented in opposite directions, with additional mass on the first tool member to compensate for these forces, reducing vibrations by canceling out oscillating mass forces of first and second order.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pivot joint of the second connecting rod is arranged on the end facing the tool members (conventional design), then the structural complexity is low and mounting space is minimized, but vibrations and transmission forces increase significantly at higher engine speeds
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the pivot joint of the second connecting rod on the end facing away from the tool members instead of toward them. This reversal of the standard configuration enables opposite orientation of the two connecting rods, which compensates oscillating mass forces and reduces vibrations at higher engine speeds.
2Object-affected harmful factors
If connecting rods are oriented in opposite directions to compensate oscillating mass forces, then vibrations are reduced, but the mounting space requirement increases
Solution Approach 1:
By inverting the orientation of the second connecting rod, the patent achieves force compensation without requiring additional mounting space. The opposite orientation allows the connecting rods to be arranged in a compact configuration that cancels oscillating mass forces while maintaining space efficiency.
3Object-affected harmful factors
If additional mass is added to the first tool member for force compensation, then vibrations are reduced, but the weight of the tool increases
Solution Approach 1:
The patent employs counterweight principles by adding mass to the first tool member to compensate for oscillating mass forces generated by the second tool member. This counterbalancing approach reduces vibrations while minimizing the increase in overall tool weight through strategic placement of the additional mass.
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 configuration significantly reduces operational vibrations and increases the service life of the power tool by minimizing transmission forces and relative movements, allowing for a simpler and more effective design with minimal mounting space enlargement.
Implementation Method 1
As a result of the opposite orientation of the two connecting rods the forces which are introduced in operation by the oscillating tool member masses, in particular the mass forces of the second order, are substantially and in particular completely compensated or canceled
Implementation Method 2
A simple configuration results when the connecting rods each are arranged on an eccentric cam wherein the eccentric cams are rotatingly driven about a common axis of rotation
Data Source
AI summary
A power tool has a drive motor and first and second tool members driven reciprocatingly by the drive motor in opposite directions, respectively. The first tool member is driven by a first connecting rod and the first connecting rod is connected to the first tool member by a first pivot joint arranged on the first connecting rod. The second tool member is driven by a second connecting rod and the second connecting rod is connected to the second tool member by a second pivot joint arranged on the second connecting rod. The first pivot joint is arranged on an end of the first connecting rod which end is facing the tool members. The second pivot joint is arranged on an end of the second connecting rod which end is facing away from the tool members.