Lawn Mower Shutter Control via Pressure Sensor
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Solution Overview
Problem
Existing lawn mowers fail to effectively prevent clogging of the grass clippings transport passage, as full-state sensors cannot detect clogging before the receptacle becomes full, leading to operational difficulties for the operator.
Innovation Solution
Incorporating a pressure sensor in the grass clippings transport passage to detect pressure variations, which allows the controller to control the shutter device and prevent clogging by maintaining the shutter in a fully open position during startup and adjusting based on pressure thresholds to anticipate and address clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full-state sensor is used to detect when the grass clippings receptacle is full, then the operator is prompted to switch from bagging mode to mulching mode, but the grass clippings transport passage can be clogged before the receptacle becomes full and the full-state sensor cannot detect this clogging
Solution Approach 1:
The pressure sensor is installed in the grass clippings transport passage to detect pressure changes before the receptacle becomes full. This preliminary detection allows the system to switch from bagging mode to mulching mode before clogging occurs, rather than waiting for the receptacle to be full. The pressure sensor monitors the transport passage continuously and triggers mode switching when abnormal pressure indicates potential clogging, preventing operational issues before they arise.
Solution Approach 2:
A pressure sensor is introduced as an intermediary detection device between the grass clippings transport passage and the control system. This pressure sensor acts as a mediator that translates physical pressure changes in the transport passage into electrical signals that the controller can process. The pressure sensor provides indirect detection of clogging conditions by measuring pressure variations, enabling the system to respond to transport passage status without directly observing the physical blockage.
2Ease of operation
If the shutter is manually operated to switch between bagging and mulching modes, then the operator has direct control, but the system cannot automatically respond to clogging conditions in the transport passage
Solution Approach 1:
The system implements a feedback loop where the pressure sensor continuously monitors the grass clippings transport passage and sends pressure data to the controller. The controller compares the detected pressure against predetermined thresholds and automatically adjusts the shutter position accordingly. This feedback mechanism enables the system to respond automatically to changing conditions in the transport passage, eliminating the need for manual operator intervention while maintaining optimal operation.
Solution Approach 2:
The lawn mower system performs self-adjustment by automatically switching between bagging and mulching modes based on pressure sensor readings. The controller autonomously controls the shutter device to maintain proper operation of the grass clippings transport passage without requiring operator attention. The system serves itself by detecting its own operational status and making necessary mode transitions independently.
3Reliability
If the pressure sensor is used to detect pressure in the grass clippings transport passage, then clogging can be prevented by controlling the shutter device, but the system complexity increases
Solution Approach 1:
The system replaces manual mechanical operation of the shutter with automated electronic control based on pressure sensor feedback. The controller uses electrical signals to actuate the shutter device, substituting the mechanical manual switching mechanism with an electronically controlled system. This substitution enables automatic response to pressure changes while reducing the complexity of manual monitoring and intervention.
Solution Approach 2:
The system utilizes pressure detection in the grass clippings transport passage, which involves pneumatic principles. The pressure sensor measures air pressure changes caused by grass clippings accumulation and transport airflow variations. By monitoring these pneumatic parameters, the system can detect clogging conditions and adjust operation accordingly, leveraging the existing pneumatic environment of the grass clippings transport system.
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 effectively prevents clogging of the grass clippings transport passage by controlling the shutter device based on pressure readings, ensuring efficient operation and reducing the burden on the operator by providing timely notifications and maintaining airflow consistency.
Implementation Method 1
a pressure sensor (65) provided in the grass clippings transport passage to detect a pressure in the grass clippings transport passage
Implementation Method 2
a cutter blade (22) rotatably provided in the housing such that when rotated, the cutter blade cuts grass and generates a transport air flow flowing from the opening of the housing to inside
Data Source
AI summary
A lawn mower contains: a work unit including a housing having a downward-facing opening and a cutter blade rotatably provided in the housing such that when rotated, 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 grass clippings cut by the work unit; a grass clippings transport passage connecting an interior of the housing with the grass clippings receptacle; a shutter device including a shutter configured to selectively open and close the grass clippings transport passage and an actuator configured to drive the shutter; a controller configured to control the shutter device; and a pressure sensor provided in the grass clippings transport passage to detect a pressure in the grass clippings transport passage, wherein the controller is configured to control the shutter device in accordance with the pressure detected by the pressure sensor.