Lawn Mower Shutter Device for Even Grass Clipping Distribution
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Solution Overview
Problem
Lawn mowers experience uneven distribution of grass clippings in the receptacle due to varying travel speed and cutter blade rotation, leading to preferential deposition near the transport passage.
Innovation Solution
A lawn mower with a controller that adjusts the shutter opening degree based on travel speed, using a speed sensor to control the shutter device, implementing reciprocal opening and closing to vary air flow velocity and prevent clogging, and employing pressure sensors to manage clogging detection and prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the shutter is kept open to collect grass clippings in the receptacle, then the bagging function is improved, but the grass clippings become unevenly distributed and preferentially deposited near the transport passage
Solution Approach 1:
The shutter device performs periodic reciprocating movements between open and closed positions. During bagging operation, instead of remaining fully open, the shutter oscillates to vary the air flow velocity and grass clippings trajectory, preventing preferential deposition near the transport passage and achieving more uniform distribution in the receptacle.
Solution Approach 2:
The shutter position is dynamically adjusted based on detected travel speed. The control unit varies the shutter opening degree according to real-time speed feedback, optimizing the balance between grass clippings collection efficiency and distribution uniformity under different operating conditions.
2Productivity
If the travel speed of the lawn mower increases, then the productivity is improved, but the amount of mowed grass clippings increases causing decreased flying distance and preferential deposition
Solution Approach 1:
A travel speed detection device continuously monitors the lawn mower's speed and provides feedback to the control unit. Based on this feedback, the control unit automatically adjusts the shutter opening degree to compensate for changes in grass clippings volume, maintaining optimal flying distance and distribution uniformity across different travel speeds.
Solution Approach 2:
The system changes the shutter opening degree parameter in response to varying travel speeds. At higher speeds where more grass clippings are generated, the shutter opening is reduced to decrease air flow velocity and extend grass clippings flying distance, preventing accumulation near the transport passage.
3Manufacturing precision
If the shutter is frequently opened and closed to improve distribution, then the grass clippings distribution is improved, but the risk of clogging in the transport passage increases
Solution Approach 1:
The shutter performs gentle reciprocating movements rather than abrupt opening and closing actions. This periodic oscillation varies air flow velocity to improve distribution while avoiding sudden pressure changes that could cause grass clippings to clog the transport passage.
Solution Approach 2:
The shutter movement is dynamically controlled with smooth transitions between positions. The gradual reciprocating motion allows grass clippings to adapt to changing air flow conditions without creating turbulence or pressure surges that would lead to clogging.
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 solution minimizes uneven distribution of grass clippings in the receptacle by adjusting air flow velocity with travel speed, preventing clogging, and ensuring even deposition across the receptacle.
Implementation Method 1
the opening degree of the shutter changes in dependence on the travel speed, the flow velocity of the transport air flow in the grass clippings transport passage varies so that the flying distance of the mowed grass clippings is varied
Implementation Method 2
when rotated, the cutter blade cuts the grass and generates a transport air flow flowing from the opening of the housing to inside
Data Source
AI summary
Uneven distribution of grass clippings in a grass clippings receptacle of a lawn mower can be minimized. A lawn mower includes: a work unit including a housing having a downward-facing opening and a cutter blade rotatably provided in the housing such that the cutter blade cuts grass and generates a transport air flow flowing from the opening of the housing to inside; a grass clippings receptacle configured to receive mowed grass clippings; a grass clippings transport passage connecting an interior of the housing with the grass clippings receptacle; a shutter device including a shutter configured to open and close the grass clippings transport passage and an actuator configured to open/close-drive the shutter; a controller configured to control the shutter device; and a speed sensor for detecting a travel speed of the lawn mower, wherein the controller is configured to open/close-control the shutter device based on the travel speed.