Cutting Unit Protection Disc With Bearings for Low-Friction Mowing

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Solution Overview

Problem

Existing lawnmower devices face issues with high friction between cutting plates and grass, leading to energy inefficiency and potential damage from collisions with ground objects, and are often designed incompatibly, requiring multiple devices for different conditions.

Innovation Solution

An accessory arrangement with a protection disc and mounting unit that can be installed on cutting units, minimizing friction and collisions by allowing the disc to remain stationary, featuring a shaft, hub, bearings, and easy mounting from the lower surface, compatible with various cutting units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cutting plate rotates directly on the ground to cut grass, then the cutting action is effective, but friction between the cutting plate and grass increases energy consumption and reduces efficiency

Engineering Contradiction:
Improvecutting efficiencyVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The cutting unit is segmented into a rotating cutting plate with blades and a stationary protection disc. The protection disc is separated from the rotating cutting plate through bearings, allowing the cutting plate to rotate while the protection disc remains stationary, minimizing friction with the grass.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protection disc acts as an intermediary element between the rotating cutting plate and the ground. It minimizes direct contact between the cutting plate and grass, reducing friction and energy consumption while protecting the cutting unit from ground objects.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the cutting plate rotates at high speed to cut tall grass, then cutting performance improves, but the risk of collision with ground objects like stones increases causing damage

Engineering Contradiction:
Improvecutting performanceVSAvoiddamage risk from collisions
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The protection disc is installed beforehand as a protective barrier between the cutting plate and ground objects. It cushions against collisions with stones and other ground objects, preventing damage to the cutting plate and blades while allowing high-speed rotation for effective cutting.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The protection disc serves as a sacrificial component that can be easily replaced if damaged. It protects the more expensive cutting plate and blades from collision damage, acting as a cost-effective protective measure.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If the cutting unit is designed with an idle protection disc mounted to the hub, then protection from ground objects is provided, but the structure becomes complex and maintenance becomes laborious

Engineering Contradiction:
Improveprotection from ground objectsVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cutting unit is divided into modular components: the cutting plate, the protection disc, and the mounting unit with bearings. This segmentation allows each component to be independently manufactured, installed, and maintained, reducing overall system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protection disc is designed to be kinematically released from the cutting plate through bearings, allowing relative rotation. This dynamic design simplifies the structure compared to rigid mounting while maintaining protective function.

Inventive Principle:
Principle #15Dynamics

4Reliability

If the cutting unit is designed with special bearings and hub configuration for the protection disc, then the protection function is achieved, but disassembly and maintenance require complete disassembly of the cutting unit

Engineering Contradiction:
Improveprotection functionVSAvoidmaintenance accessibility
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The mounting unit is designed as a separate module that can be independently removed from the cutting plate. This segmentation allows maintenance personnel to access and service the protection disc and bearings without disassembling the entire cutting unit, significantly improving maintenance accessibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protection disc and mounting unit can be extracted from the cutting plate as a separate assembly. This extraction capability enables easy maintenance and replacement of protective components without affecting the cutting plate or blades.

Inventive Principle:
Principle #2Taking out (Extraction)

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

Enhances cutting efficiency, reduces energy consumption, increases autonomy, and allows retrofitting and easy maintenance, providing a flexible and cost-effective solution for various ground and weather conditions.

Implementation Method 1

at least one pair of bearings operatively active between said shaft and said hub and configured to allow a relative rotation between said shaft and said hub

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4578259A1Accessory arrangement for a cutting unit, relative cutting unit and mobile device comprising the accessory arrangement
Publication Date: 2025.07.02 STIGA S P A IN BREVE ANCHE ST SPA
  • EP4578259A1 patent drawingFigure 1~2
  • EP4578259A1 patent drawingFigure 3
  • EP4578259A1 patent drawingFigure 4

AI summary

The present invention relates to an accessory arrangement (10) for a cutting unit (100) of a mobile device (200) having a cutting plate (1) provided with a support body (2) and at least one blade (3). The accessory arrangement (10) comprises a protection disc (4) and a mounting unit (5) adapted to connect the protection disc to the cutting plate (1). The mounting unit comprises: a shaft (51) configured to be constrained to a lower surface (21) of the support body of the cutting plate, a hub (52) fitted on the shaft, a pair of bearings (53, 54), an axial support member (57) and first fixing means (55).