Cutter Guard Apertures for Robotic Mower Debris Management

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Solution Overview

Problem

Conventional rotary lawn mowers with debris build-up issues are exacerbated in battery-operated robotic mowers, where lower power motors struggle with debris accumulation, leading to reduced operational efficiency due to small grass elements sticking and building up on the cutter guard.

Innovation Solution

A cutter guard design featuring a planar section surrounded by an arcuate section with multiple apertures, allowing grass cuttings to pass through while preventing finger access, combined with an air stream to remove debris, optimizing the structure for robotic lawn mowers with smaller motors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a conventional solid cutter guard is used to protect the blade, then user safety is improved, but debris build-up increases and operational efficiency deteriorates

Engineering Contradiction:
Improveuser safetyVSAvoidoperational efficiency
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The cutter guard incorporates an arcuate section with multiple apertures (5-7 holes) that allow grass cuttings and debris to pass through while maintaining protective coverage. This porous structure prevents debris accumulation on the guard surface, eliminating the need for high-power motors to maintain cutting performance.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The cutter guard is divided into distinct functional sections: a planar section providing structural base, an arcuate section with apertures for debris ejection, and lip sections for guiding grass flow. This segmentation allows each part to perform its specific function optimally while working together to prevent debris build-up.

Inventive Principle:
Principle #1Segmentation

2Use of energy by moving object

If a smaller lower-powered motor is used to conserve battery power, then energy consumption is improved, but the motor struggles with debris accumulation leading to reduced cutting performance

Engineering Contradiction:
Improvebattery power consumptionVSAvoidcutting performance consistency
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The cutter guard design enables self-cleaning functionality where grass cuttings are automatically ejected through the apertures in the arcuate section. The lip sections guide grass flow to prevent sticking, and the apertures allow debris to be thrown clear by the cutting action itself, eliminating the need for additional power-consuming mechanisms.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The guard structure changes the physical parameters of debris interaction by providing apertures that alter the flow path of grass cuttings. This prevents the accumulation that would otherwise increase drag on the blades and allow smaller motors to maintain consistent cutting performance throughout battery operation.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the arcuate section has more apertures to prevent debris build-up, then operational efficiency is improved, but the structural strength of the guard may be compromised

Engineering Contradiction:
Improvedebris ejection efficiencyVSAvoidguard structural strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The apertures are strategically positioned and sized (5-7 holes of appropriate dimensions) in the arcuate section to provide sufficient debris ejection capability while maintaining structural integrity. The distribution and configuration of apertures are optimized to balance open area for debris passage with remaining material for structural strength.

Inventive Principle:
Principle #3Local quality

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 design effectively prevents debris build-up, enhances operational efficiency by allowing uncut grass access and expelling cuttings, and provides adequate protection for the blade while conserving power in robotic mowers.

Implementation Method 1

An air stream may be provided to blow across the underside of the cutter guard to assist in the removal of grass cuttings and other debris from the cutter guard and the cutter.

Methodology Applied
Scientific EffectAir stream: Fluid Spray

Data Source

PatentEP2656720B1Cutter guard for a lawn mower
Publication Date: 2015.11.04 ROBERT BOSCH GMBH
  • EP2656720B1 patent drawingFigure 1~2
  • EP2656720B1 patent drawingFigure 3
  • EP2656720B1 patent drawingFigure 4~5

AI summary

The present invention relates to a cutter guard for a rotating blade of a lawn mower, particularly for a robotic, self-guided or autonomous lawn mower. We describe a cutter guard for a rotatable blade of a robotic rotary lawn mower, the guard forming a cutting bowl in which said blade is mounted for rotation about a generally vertical axis; and wherein said guard comprises, a generally planar guard section surrounded by an arcuate section, transverse edges of which define an opening in said cutter guard, which in operation is pointed to the front of said lawn mower, to allow uncut grass to be accessed by the cutting blades, said arcuate section comprising a plurality of apertures.