Elastomer Cutting Disc Structure for Quieter Robotic Lawn Mowers
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Solution Overview
Problem
Robotic lawn mowers can produce disturbing noise, particularly when cutting thick grass, due to the impact and vibration of cutting discs.
Innovation Solution
The cutting disc is partially or entirely made of an elastomer material with a Young's modulus lower than 0.1 GPa, combined with a stiffer plastic material, using two-shot injection molding to provide noise dampening and rotational symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional rigid cutting disc is used, then the structural strength and cutting performance are maintained, but noise and vibration increase significantly
Solution Approach 1:
The cutting disc combines a rigid support structure (for structural strength) with elastomer material (for noise dampening). This composite construction allows the disc to maintain necessary mechanical strength while the elastomer component absorbs vibrations and reduces noise from knife impacts and rattling.
Solution Approach 2:
The patent changes the material parameter (Young's Modulus) by introducing elastomer material with lower stiffness compared to traditional rigid plastics. This parameter change enables the cutting disc to deform elastically under impact, dissipating energy and reducing noise while maintaining functional integrity.
2Object-affected harmful factors
If elastomer material is used to reduce noise, then noise dampening improves, but the cutting disc weight increases
Solution Approach 1:
The elastomer material is applied locally in specific areas where noise generation occurs (such as around the knife carriers and shaft connector) rather than throughout the entire cutting disc. This localized application provides effective noise dampening while minimizing the additional weight compared to a fully elastomer construction.
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 elastomer material effectively reduces noise and vibration, resulting in a more silent operation of the robotic lawn mower.
Implementation Method 1
an elastomer material through its thickness with a Young's Modulus lower than 0,1 GPa for small strain deformation
Implementation Method 2
reduce noise by dampening impacts from the knives that can make the cutting disc rattle considerably
Data Source
Figure 1~2
Figure 3~6
AI summary
The present disclosure relates to a robotic lawn mower 51, and a cutting disc 1 therefore. The cutting disc comprises at the center of the disc a shaft connector 3, for connecting the cutting disc 1 to a robotic mower driving shaft 53. At the periphery of the disc, a plurality of knife carrier arrangements 7 are provided, each being configured to carry a grass-cutting knife pivotally attached thereto. The cutting disc comprises at least partially along a path from the shaft connector 3 to a knife carrier arrangement 7 an elastomer material through its thickness with a Young's modulus lower than 0,1 GPa. This serves to dampen noise that can arise from the grass-cutting knives impacting thick material, and which can be amplified by the cutting disc.