Tool Head Linkage Design for Vibration Reduction
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Solution Overview
Problem
Hand-held mowing devices experience high vibrations due to the oscillating movement of blade disks and associated gear masses, leading to reduced operational efficiency and user discomfort.
Innovation Solution
The tool head design positions the second joint axis and fourth joint axis on opposite sides of a central plane spanned by the axis of rotation and coupling drive axis, balancing gear forces and reducing vibrations through symmetric arrangement of drive and coupling linkages, with a large ring gear acting as a flywheel for uniform movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If linkage gears are used to drive reciprocating cutting discs, then the cutting function is achieved, but high vibrations occur during operation
Solution Approach 1:
The patent applies asymmetry by arranging the second and fourth articulation axes on opposite sides of the median plane, creating an asymmetric configuration that balances transmission forces. This asymmetric arrangement causes the inertial forces from the two linkage gears to counterbalance each other, significantly reducing vibrations during operation while maintaining the cutting function.
2Object-affected harmful factors
If the second and fourth articulation axes are arranged on opposite sides of the median plane, then vibrations are reduced, but the device complexity increases
Solution Approach 1:
The patent merges the two linkage gears into a coordinated system where both are driven by a common drive element (eccentric mechanism). By combining their operation and synchronizing their motion through the shared drive, the system achieves force balancing that reduces vibrations, while the integrated design prevents excessive complexity.
3Device complexity
If a common drive element drives both linkage gears, then the structure is simplified, but vibrations increase due to oscillating movement
Solution Approach 1:
The patent applies the counterweight principle by positioning the two linkage gears such that their oscillating movements and associated inertial forces act in opposition to each other. The arrangement of articulation axes on opposite sides of the median plane creates a counterbalancing effect where the vibrations from one linkage gear are offset by the other, reducing overall vibrations despite using a common drive element.
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
Significantly reduces vibrations during operation, enhancing user comfort and operational efficiency by balancing gear forces and providing a compact, powerful cutting mechanism with multiple cuts per revolution.
Implementation Method 1
a large ring gear acting as a flywheel for uniform movement
Implementation Method 2
the transmission forces, in particular the transmission forces of the second transmission order, are at least partially, and in particular completely, balanced
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A tool head (51) for a hand-held tool (1) has two rotatably mounted tools (8, 9), wherein a first tool (8) can be driven via a first linkage (42) and a second tool (9) can be driven via a second linkage (43). The tools (8, 9) can be driven in opposite directions about a common axis of rotation (10) via the linkages (42, 43). The first linkage (42) has a first drive element (22) which is pivotably coupled to a first linkage (18) about a first pivot axis (34). The first linkage (18) is pivotably coupled to the first tool (8) about a second pivot axis (28). The second linkage (43) has a second drive element (23) which is pivotably coupled to a second linkage (19) about a third pivot axis (35). The second coupling element (19) is pivotably coupled to the second tool (9) about a fourth joint axis (29).The axis of rotation of the tools (8, 9) and the linkage drive axis (21) define a median plane (30) that runs between the second articulation axis (28) and the fourth articulation axis (29). A hand-held tool (1) has a drive motor (3), a drive shaft (5), and a tool head (51) with two linkage drives (42, 43).