Reel Mower Cutting Unit Rolling Connection

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Solution Overview

Problem

Reel lawn mowers face issues with the cutting reel biting into the sod due to ground undulation, particularly as the rotation center of the reel cutting unit deteriorates over time, leading to reduced clearance and increased likelihood of contact with the ground, especially on inclined surfaces.

Innovation Solution

A reel lawn mower design where the reel cutting unit is connected to the main body to roll around a virtual center point that aligns with the reduced diameter of the cutting reel, maintaining a consistent clearance and preventing biting into the sod by ensuring the rotation center remains within the cutting reel's dimensions even as it deteriorates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the reel cutting unit is connected to the main body with a rotation mechanism allowing pitching and rolling, then the reel cutting unit can follow ground surface undulation, but the rotation center position deteriorates over time causing the cutting reel to bite into the sod

Engineering Contradiction:

Improveability to follow ground surfaceVSAvoidcutting reel clearance stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The connection structure allows the reel cutting unit to dynamically adjust its position through pitching and rolling motions, enabling it to adapt to varying ground surfaces while maintaining proper cutting clearance through controlled rotation around a fixed virtual center point

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The connection structure acts as an intermediary mechanism between the main body and reel cutting unit, providing the necessary degrees of freedom for ground following while constraining the rotation to occur around a predetermined virtual center point that prevents biting

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the rotation center is positioned above the cutting reel, then pitching and rolling motions are enabled, but the cutting reel breaks into the sod on inclined ground surfaces

Engineering Contradiction:

Improvepitching and rolling motion capabilityVSAvoidcutting reel biting into sod

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The connection structure is designed with asymmetric geometry where the virtual center point of rotation is deliberately positioned at a specific location that is not directly above the cutting reel axis, creating an offset that prevents the cutting reel from biting into inclined ground surfaces while still enabling necessary pitching and rolling motions

Inventive Principle:

Principle #4Asymmetry

3Productivity

If the cutting reel diameter decreases due to wear, then cutting efficiency reduces, but the rotation center position shifts causing increased likelihood of ground contact

Engineering Contradiction:

Improvecutting efficiencyVSAvoidclearance maintenance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The connection structure is designed based on a virtual model where the virtual center point of rotation is calculated and positioned to account for the cutting reel's initial dimensions, creating a geometric copy of the ideal rotation geometry that maintains proper clearance even as the physical cutting reel wears and shrinks in diameter

Inventive Principle:

Principle #26Copying

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

This design effectively prevents the cutting reel from biting into the sod across varying ground surfaces and undulations, maintaining a consistent clearance and ensuring efficient grass cutting without damaging the lawn, even as the cutting reel's diameter decreases due to wear.

Implementation Method 1

the reel cutting unit rolls around a virtual center point which is in a vertical projection plane covering the cutting reel with a diameter reduced to the limit for use and located in the center of the axial direction of the cutting reel

Methodology Applied

Scientific EffectRolling motion:

Data Source

PatentUS9027318B2Reel lawn mower with main body, reel cutting unit, and connection structure for connecting reel cutting unit to main body such that reel cutting unit is rollable

Publication Date: 2015.05.12 KYOEISHA SHIBAURA INC

AI summary

A reel lawn mower which has a connection structure for connecting a reel cutting unit to a main body. The reel cutting unit has a spiral cutting reel which is rotated by a prime mover to cut grass together with a bedknife. In the connection structure, in order to connect the reel cutting unit to the main body so that the reel cutting unit rolls around a virtual horizontal line perpendicular to the shaft center of the cutting reel in the center of the axial direction of the cutting reel, the reel cutting unit includes a connecting arm with an arc portion shaped so as to follow a virtual arc centered on the virtual horizontal line. The connecting arm is slidably supported so as to prevent the arc portion from coming off the virtual arc.