Robotic Lawnmower Cutter Assembly for Low-Friction Easy Servicing

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Solution Overview

Problem

Robotic lawnmowers require regular maintenance, such as resharpening or replacing grass cutting knives, and have high energy consumption, especially in large installations, leading to increased operational costs.

Innovation Solution

A lawnmower cutter assembly with a knife carrier arrangement and skid plate arrangement that can be easily removed and attached to a cutter drive shaft, featuring a skid plate that reduces friction and a keyed interface for precise positioning, allowing for efficient servicing and reduced energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the knife carrier arrangement and skid plate arrangement are permanently fixed to the cutter drive shaft, then the structural stability is improved, but the ease of maintenance deteriorates

Engineering Contradiction:
Improvestructural stabilityVSAvoidease of maintenance
Core Design Contradiction:
Stability of the object's compositionVSEase of repair

Solution Approach 1:

The cutter assembly is divided into separable components: the knife carrier arrangement, the skid plate arrangement, and the cutter drive shaft. Each component can be independently removed and serviced, allowing maintenance without replacing the entire assembly. The skid plate can be detached to service knives, and the whole assembly can be removed from the drive shaft for major servicing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection between components is designed to be dynamically adjustable between fixed and removable states. The skid plate arrangement can be fixed during operation for stability, but easily removed when maintenance is needed. This dynamic connectivity resolves the contradiction between stability during use and ease of maintenance.

Inventive Principle:
Principle #15Dynamics

2Loss of energy

If the skid plate is designed to cover the knife carrier arrangement completely, then the friction reduction is improved, but the ease of access for maintenance deteriorates

Engineering Contradiction:
Improvefriction lossesVSAvoidaccess for maintenance
Core Design Contradiction:
Loss of energyVSEase of repair

Solution Approach 1:

The skid plate is designed as a separate, removable component rather than a permanent cover. This segmentation allows the skid plate to provide friction reduction during operation while enabling easy access to the knife carrier arrangement when maintenance is needed. The skid plate can be removed to service the knives without disassembling the entire cutter assembly.

Inventive Principle:
Principle #1Segmentation

3Manufacturing precision

If multiple separate fasteners are used to secure the knife carrier and skid plate, then the manufacturing precision is improved, but the device complexity increases

Engineering Contradiction:
Improvepositioning precisionVSAvoidnumber of fasteners
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Multiple fastening functions are merged into a single integrated fastening mechanism. The skid plate arrangement includes a fastening feature that simultaneously secures both the skid plate and the knife carrier arrangement to the cutter drive shaft, eliminating the need for multiple separate fasteners while maintaining precise positioning.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single fastening mechanism serves multiple functions: it secures the skid plate, holds the knife carrier arrangement in position, and provides alignment. This multi-functional design achieves manufacturing precision without increasing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4145979B1Robotic lawnmower cutter assembly, robotic lawnmower, and method of attaching a lawnmower cutter assembly to a lawnmower
Publication Date: 2026.03.18 HUSQVARNA AB
  • EP4145979B1 patent drawingFigure 1~2
  • EP4145979B1 patent drawingFigure 3~4
  • EP4145979B1 patent drawingFigure 5

AI summary

A lawnmower cutter assembly (22) comprises a knife carrier arrangement (26) and a skid plate arrangement (30), which are axially held between an axial stop shoulder (60) of the cutter drive shaft (34) and an end piece (54) rigidly connected to the cutter drive shaft (34), the end piece (54) thereby vertically carrying the skid plate arrangement (30) and the knife carrier arrangement (26). The cutter assembly (22) may be attached to a lawnmower, which may be a robotic lawnmower, by positioning the knife carrier arrangement (26) and the skid plate arrangement (30) on the cutter drive shaft (34); and thereafter, axially locking the axial position of the knife carrier arrangement (26) and the skid plate arrangement (30) in relation to the cutter drive shaft (34).