Segmented Lawnmower Blade and Grid for Grass Flow

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Solution Overview

Problem

Existing lawnmower cutting decks face issues with high friction, low cutting efficiency, energy consumption, and accumulation of cut grass residue, which complicates cleaning and safety concerns due to complex designs and frequent maintenance requirements.

Innovation Solution

A cutting blade design featuring a flat solid disc-shaped central portion with radial blades extending horizontally, where only the end portion with cutting edges contacts the grass, and a protection grid with an obstruction-free opening to reduce grass accumulation and energy consumption, while enhancing safety and aerodynamics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection grid is mounted under the cutting deck to protect the cutting blade, then safety is improved, but a very large cut grass residue remains inside the cutting deck, preventing effective cutting

Engineering Contradiction:
ImprovesafetyVSAvoidcutting efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The protection grid is segmented into multiple parallel elements spaced apart, creating gaps between them. This segmentation allows cut grass residue to pass through the grid more easily, reducing accumulation while maintaining the protective function of covering the cutting blade area.

Inventive Principle:
Principle #1Segmentation

2Reliability

If a protection grid is mounted under the cutting deck, then safety is improved, but the cutting deck must be cleaned very frequently by removing the protection grid

Engineering Contradiction:
ImprovesafetyVSAvoidcleaning frequency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The protection grid is designed as segmented parallel elements rather than a solid structure, allowing grass residue to pass through. This reduces the amount of residue accumulating on the grid, thereby reducing cleaning frequency and time required while maintaining safety coverage.

Inventive Principle:
Principle #1Segmentation

3Reliability

If a flat solid disc-shaped safe cutting blade is used, then safety is improved, but the cutting efficiency is very low

Engineering Contradiction:
ImprovesafetyVSAvoidcutting efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The flat solid disc blade is segmented into multiple radial blades extending from the central portion. This segmentation creates multiple cutting edges that can simultaneously cut grass, significantly improving cutting efficiency while maintaining the safe enclosed design within the cutting deck.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cutting blade design extends vertically with radial blades at different heights, with only the end portions contacting the grass on the cutting plane. This dimensional arrangement reduces friction from the central portion while maintaining effective cutting at the blade ends.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Reliability

If a rotating box with multiple cutting blades is used, then safety is improved, but the apparatus is complicated to manufacture and clean

Engineering Contradiction:
ImprovesafetyVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The complex rotating box structure is extracted and replaced with a simpler design where cutting blades are directly mounted on a disc-shaped central portion. This extraction of the essential cutting function eliminates unnecessary enclosing structures, simplifying manufacturing while maintaining safety through the protected cutting deck design.

Inventive Principle:
Principle #2Taking out (Extraction)

5Reliability

If a rotating box with multiple cutting blades is used, then safety is improved, but the lawnmower consumes more energy to rotate the cutting blade

Engineering Contradiction:
ImprovesafetyVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The cutting blade design elevates the central portion above the cutting plane, with only the end portions of radial blades contacting the grass. This dimensional change reduces the friction and energy required to rotate the blade, as the central portion does not drag against the grass while maintaining effective cutting at the blade ends.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3335538B1Lawnmower with a safe cutting deck
Publication Date: 2020.11.04 STIGA S P A IN BREVE ANCHE ST SPA
  • EP3335538B1 patent drawingFigure 1
  • EP3335538B1 patent drawingFigure 2
  • EP3335538B1 patent drawingFigure 3~4

AI summary

A lawnmower is described comprising a cutting deck and a safety apparatus mounted with the cutting deck, which comprises a cutting blade (1), which comprises a flat solid disc-shaped central portion (2) on a horizontal geometric plane (H) and a multiplicity of radial blades (3) on a lower horizontal geometric cutting plane (C), and a protection grid (7), which is fixedly mounted with the cutting deck and covers the entire action range of said cutting blade (1), comprising a multiplicity of connecting means (9) between a support boundary element (76) and an inner ring (8) with an obstruction-free through opening (800). (Figure 1).