Lawnmower Guide Member for Grass Flow Control

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Solution Overview

Problem

Rotary lawnmowers experience grass buildup when used in bagging mode due to the difference in revolving flow speeds within the housing, leading to inefficient storage and frequent cleaning needs.

Innovation Solution

Incorporating a guide member inside the housing to direct cut grass from low-speed areas around the shaft to the outer periphery, where the flow speed is higher, and a shutter mechanism with a kicker to manage the flow during mulching mode, ensuring efficient delivery to the cut grass conveyor passage and storage container.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the lawnmower operates in bagging mode with a revolving flow, then cut grass is delivered to the storage container, but grass buildup occurs around the shaft due to low flow speed in the vicinity of the shaft

Engineering Contradiction:
Improvecut grass delivery efficiencyVSAvoidgrass buildup prevention
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The guide member is strategically positioned at the low-speed region near the shaft to locally improve grass flow guidance. This component creates a localized quality change by directing grass from the low-speed central region toward the high-speed outer periphery, preventing grass buildup specifically where the flow speed is insufficient while maintaining the overall revolving flow structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The guide member acts as an intermediary element between the low-speed central flow region and the high-speed outer flow region. It mediates the grass flow by guiding it from the shaft vicinity outward to the periphery, enabling smooth transition and preventing accumulation without disrupting the overall revolving flow pattern needed for efficient grass delivery.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the guide member directs grass to the outer periphery, then grass buildup is prevented, but the housing structure becomes more complex

Engineering Contradiction:
Improvegrass buildup preventionVSAvoidhousing structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The guide member is designed as a separate, modular component that can be independently installed within the housing. This segmentation allows the guidance function to be added without redesigning the entire housing structure, maintaining manufacturing simplicity while achieving reliable grass flow control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The guide member utilizes the existing revolving flow dynamics of the system to achieve its function. By positioning it to leverage the natural velocity difference between the central and peripheral regions, it guides grass outward using the system's own flow characteristics rather than requiring additional energy input or complex mechanical actuation.

Inventive Principle:
Principle #25Self-service

3Productivity

If cut grass is delivered efficiently to the conveyor passage, then storage performance is improved, but grass may stop around the shaft due to low revolving flow speed

Engineering Contradiction:
Improvestorage performanceVSAvoidmaintenance frequency
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The guide member performs preliminary action by directing grass away from the shaft region before grass buildup can occur. This preventive guidance ensures that grass is continuously moved toward the outer periphery and into the conveyor passage, eliminating the need for frequent cleaning and maintenance while maintaining high storage performance.

Inventive Principle:
Principle #10Preliminary action

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

Prevents grass buildup, enhances storage performance by ensuring all cut grass is efficiently stored in the container, reducing maintenance frequency and improving discharge efficiency during mulching mode.

Implementation Method 1

the cutting blade cuts grass and creates a revolving flow around the shaft within the housing. The grass that has been cut (in other words, the cut grass) is made to revolve around the shaft within the housing by the revolving flow.

Methodology Applied
Scientific EffectRevolving flow: Vortex Ring

Data Source

PatentEP2258161B1Lawnmower
Publication Date: 2012.04.04 HONDA MOTOR CO LTD
  • EP2258161B1 patent drawingFigure 1
  • EP2258161B1 patent drawingFigure 2
  • EP2258161B1 patent drawingFigure 3

AI summary

A lawnmower including a cut grass storage container (22) for storing cut grass. The lawnmower also includes a cutting blade (14), a downwardly-opening housing (11), and a cut grass conveyor passage (21). The cut grass storage container is provided to the cut grass conveyor passage (21). Grass that has been cut is delivered to the cut grass conveyor passage while revolving about a shaft (SC) inside the housing (11). A guide member (25) is provided inside the housing (11). The guide member (25) guides the revolving grass to the cut grass conveyor passage (21) while guiding the grass to the outer periphery of the housing (11).