Door Prop Mechanism for Lawn Mower Discharge Control

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Solution Overview

Problem

Walk-behind lawn mowers with spring-biased doors pose challenges during the installation and removal of collection bags, as the door must be manually held open, and there is no efficient mechanism to switch between blocking and exposing the discharge for mulching and bag collection operations.

Innovation Solution

A walk-behind mower design featuring a movably mounted door with a door prop system, allowing the door to be easily switched between blocking and exposing the discharge, using a handle-operated mechanism to control the door's position, facilitating bag installation and removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spring-biased door is used to block the discharge opening, then the door automatically closes to maintain mulching function, but the door must be manually held open during collection bag installation and removal

Engineering Contradiction:
ImproveDoor operation during bag installationVSAvoidDoor control mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

A door prop serves as an intermediary element between the door and the collection bag. The door prop engages with the door to hold it in the open position during bag installation and removal, eliminating the need for manual holding while maintaining simplicity of the overall system.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the door is kept closed for mulching operation, then grass is contained on the cutting platform, but the discharge opening cannot be accessed for collection bag mating

Engineering Contradiction:
ImproveDischarge opening accessibilityVSAvoidBag installation convenience
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The door is designed to be dynamically positionable between closed and open states. The door prop enables the door to be easily moved to the open position when needed for bag installation, and the spring mechanism automatically returns it to the closed position for mulching operation, providing adaptability for different operational modes.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If manual holding of the door open is required, then simple spring biasing is sufficient, but operator convenience and safety are reduced

Engineering Contradiction:
ImproveDoor holding convenienceVSAvoidDoor positioning mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The door prop system provides self-service functionality by automatically engaging with the door to hold it in the desired open position. The spring mechanism automatically returns the door to the closed position when the prop is disengaged, eliminating the need for continuous manual intervention while maintaining operational simplicity.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2400830B1Door prop in a lawn mower
Publication Date: 2019.02.27 HUSQVARNA AB
  • EP2400830B1 patent drawingFigure 1
  • EP2400830B1 patent drawingFigure 2~3
  • EP2400830B1 patent drawingFigure 4~5

AI summary

A mower for cutting grass includes a platform with a motor located thereon. A door on the platform has a first position blocking a discharge and a second door position away from the discharge. A bag has an inlet that mates to a discharge. A support is connected to the platform and a door prop is movably mounted on the support. The door prop has a first position not in engagement with the door to permit the door to be in the first position and having a second position in which a segment of the door prop engages with the door to retain the door in the second position. A handle extends up from the platform. An operable member is mounted on the handle. A connector extends between the door prop and the operable member to transmit force to move the door prop.