Lawn Mower Flap Angle Control for Noise and Productivity Trade-off
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Solution Overview
Problem
Existing rotary lawn mowers face inefficiencies in cutting and transporting grass clippings due to varying lawn conditions, requiring manual adjustment by operators to maintain consistent cutting quality and efficiency, leading to laborious operations and noise issues at higher rotation speeds.
Innovation Solution
A lawn mower equipped with a cutter blade, engine, throttle valve, and adjustable flap with an actuator and control unit that automatically adjusts rotation speed and flap angle based on detected changes in lawn conditions to optimize airflow and reduce noise, ensuring efficient cutting and transportation regardless of lawn conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotation speed of the cutter blade is increased to improve lawn mowing performance and transportation efficiency, then cutting efficiency and grass clippings transport are improved, but noise levels increase
Solution Approach 1:
The flap angle is made dynamically adjustable based on real-time detection of lawn conditions and engine load. The control unit automatically modifies the flap angle to optimize airflow and reduce noise without sacrificing cutting performance, allowing the system to adapt its configuration to operating conditions rather than maintaining a fixed state
Solution Approach 2:
The system changes physical parameters (flap angle, rotation speed) based on detected lawn conditions and engine performance. By adjusting the flap angle parameter in response to varying loads and speeds, the system optimizes the balance between cutting efficiency and noise generation, achieving quiet operation at high speeds when appropriate
2Productivity
If the rotation speed of the cutter blade is increased to improve transportation performance, then grass clippings transport to container is improved, but noise is generated louder
Solution Approach 1:
The system incorporates feedback mechanisms through sensors that detect engine load, rotation speed, and lawn conditions. This feedback loop enables the control unit to continuously adjust the flap angle in response to actual operating conditions, optimizing transportation performance while minimizing noise generation through real-time parameter modification
3Manufacturing precision
If manual adjustment of throttle valve is required to maintain consistent cutting quality under varying lawn conditions, then cutting quality is maintained, but labor efficiency decreases
Solution Approach 1:
The system performs self-adjustment of the throttle valve and flap angle based on automatic detection of lawn conditions and engine load. The control unit processes sensor data and modifies operational parameters without human intervention, enabling the system to maintain consistent cutting quality across varying conditions while eliminating the need for manual adjustment and improving overall work efficiency
4Productivity
If the flap angle is increased to generate more upward air flow for heavy lawn grass, then cutting efficiency is improved, but noise and energy consumption increase
Solution Approach 1:
The flap angle is dynamically adjusted based on real-time detection of lawn conditions and engine load. For heavy, wet grass conditions, the system increases the flap angle to generate sufficient upward airflow for efficient cutting. For lighter or drier conditions, it reduces the flap angle to minimize noise and energy consumption, optimizing performance for each specific scenario
Solution Approach 2:
The system modifies the flap angle parameter in response to detected lawn conditions and operational requirements. By changing this physical parameter dynamically, the system achieves high cutting efficiency when needed while reducing noise generation during lighter operations, adapting to varying demands without compromise
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
The system improves work efficiency by automatically adapting to changing lawn conditions, reducing noise, and maintaining consistent cutting quality without manual intervention, enhancing fuel economy and handling changes in lawn load effectively.
Implementation Method 1
a cutter blade rotatable about a rotation shaft extending in a vertical direction
Implementation Method 2
an engine configured to drive the cutter blade through the rotation shaft
Implementation Method 3
a throttle valve provided for the engine
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A control unit (117) of a lawn mower (10) performs switching control for switching operation between a first control mode and a second mode. In the first control mode, during rotation of an engine (15) at a first reference rotation speed (N1), in the case where a change amount (ΔNer) of rotation speed (Ner) of the engine (15) per unit time has exceeded a reference speed change amount (ΔNs), the rotation speed (Ner) is maintained at a second reference rotation speed (N2), and an flap angle (θr) is increased. In the second control mode, during rotation of the engine (15) at a second reference rotation speed (N2), in the case where an opening angle (αr) of a throttle valve (125) has fallen below a reference opening angle (αs), the rotation speed (Ner) is maintained at the first reference rotation speed (N1), and the flap angle (θr) is decreased. The second reference rotation speed (N2) is higher than the first reference rotation speed (N1).