Lawn Mower Flap Control for Grass Jamming Prevention

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Solution Overview

Problem

The existing rotary lawn mowers face issues with grass clippings jamming in the container, leading to reduced durability and increased operational labor due to inefficient wind flow management, which causes collisions between the cutter blade and clippings when the container reaches its storage capacity.

Innovation Solution

A lawn mower equipped with a flap mechanism that can change its angle, controlled by an actuator and a control unit, which detects the weight and internal pressure of the clippings container to adjust the flap position and wind flow, preventing jamming and notifying the operator of capacity limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If transportation of grass clippings is continued after the container reaches storage capacity limit, then the container can store more clippings, but jamming occurs between the cutter blade and housing causing reduced durability

Engineering Contradiction:

Improvestorage capacity of grass clippings containerVSAvoiddurability of cutter blade and housing

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The system uses weight detection means to continuously monitor the weight of grass clippings in the container and provides feedback to the control means. When the weight reaches a predetermined threshold indicating full capacity, the control means automatically adjusts the flap angle to prevent further clippings from entering, thus avoiding jamming while maximizing storage utilization.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The lawn mower system performs self-monitoring and self-adjustment through the weight detection means and control means working together. The system automatically detects when the container is full and autonomously adjusts the flap position without operator intervention, preventing damage before it occurs.

Inventive Principle:

Principle #25Self-service

2Reliability

If the flap angle is adjusted to prevent jamming, then durability is improved, but the complexity of the system increases due to additional control mechanisms

Engineering Contradiction:

Improvedurability of drive sourceVSAvoidcomplexity of flap control system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system replaces complex mechanical monitoring and adjustment mechanisms with electronic sensors and control circuitry. The weight detection means uses electronic sensing to monitor clippings weight, and the control means uses electronic signals to actuate the flap position, simplifying the overall system architecture while improving reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The flap actuation mechanism may utilize pneumatic or hydraulic principles through the drive source to adjust the flap angle. This allows for smooth, controlled movement of the flap without requiring complex mechanical linkages, reducing system complexity while maintaining precise control capability.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Reliability

If weight detection means and control system are added, then jamming is prevented, but the manufacturing cost increases

Engineering Contradiction:

Improvedurability of lawn mowerVSAvoidmanufacturing cost of lawn mower

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

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 solution effectively prevents jamming by adjusting the wind flow, reducing collisions and improving the durability of the mower and drive source, while also notifying the operator of storage capacity limits, thus enhancing operational efficiency.

Implementation Method 1

a grass clippings container weight detection unit configured to detect weight of the grass clippings container

Methodology Applied

Scientific EffectWeight detection:

Implementation Method 2

an internal pressure detection unit configured to detect internal pressure of the housing

Methodology Applied

Scientific EffectPressure detection:

Implementation Method 3

transported from the housing by transportation wind generated by the cutter blade

Methodology Applied

Scientific EffectWind flow generation:

Data Source

PatentEP3210454B1Lawn mower

Publication Date: 2018.12.12 HONDA MOTOR CO LTD

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AI summary

A lawn mower (10) includes a housing (11), a drive source (15), flaps (52), a grass clippings container (22), a grass clippings container weight detection unit (113), an internal pressure detection unit (111), and a control unit (117). If it is determined that a first condition where a change amount (ΔWr) per predetermined fixed time (Δt1) of the weight (Wr) detected by the grass clippings container weight detection unit (113) is below a weight change amount reference value (ΔWs) and a second condition where a change amount (ΔPr) per predetermined fixed time (Δt2) of the internal pressure (Pr) detected by the internal pressure detection unit (111) has increased to a internal pressure change amount reference value (ΔPs), are satisfied, the control unit (117) implements control to place the flaps (52) in a substantially horizontal state.