Garden Tool Blade Position Sensing via Magnetic Field
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Solution Overview
Problem
Existing garden tools with opposing blades face issues due to wear and tear, leading to inconsistent blade travel distance, which affects cutting efficiency and tool utility, as the blades may overtravel or undertravel, reducing their effectiveness over time.
Innovation Solution
A parallel position sensing system is introduced, comprising a driveshaft coupled to blades, a motor, a threaded shaft, a magnet, and a proximity sensor. The system translates the driveshaft linearly, changing the distance between the magnet and the proximity sensor, which adjusts the output voltage. This voltage signal is used by a controller to manage motor power, preventing overtravel by discontinuing energy transmission when the blades reach predetermined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If no sensing system is used, then the device complexity is low, but the blade travel distance control precision deteriorates due to wear and tear
Solution Approach 1:
The patent replaces complex mechanical sensing mechanisms with a magnetic field-based sensing system. A magnet attached to the movable blade interacts with a proximity sensor, eliminating the need for mechanical linkages, gears, or contact-based position detection. This substitution maintains high measurement precision while reducing mechanical complexity and wear.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the movable blade and the sensing system. The magnet on the blade creates a magnetic field that the proximity sensor detects, allowing non-contact position measurement. This intermediary enables precise travel distance control without direct mechanical contact, reducing wear and maintaining precision over time.
2Reliability
If wear and tear occurs over time, then the device complexity remains the same, but the blade travel distance precision deteriorates leading to overtravel
Solution Approach 1:
The patent implements a feedback control system where the proximity sensor continuously monitors the position of the movable blade and provides signals to the controller. The controller uses this feedback information to adjust motor operation, ensuring the blade reaches and stops at the precise predetermined position. This closed-loop feedback maintains consistent travel distance reliability even as mechanical components experience wear and tear over time.
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 effectively controls blade travel distance, preventing overtravel and maintaining cutting efficiency by ensuring blades operate within predetermined limits, thus extending the tool's lifespan and performance.
Implementation Method 1
A magnet is coupled to the driveshaft. A proximity sensor is positioned in magnetic communication with the driveshaft. A change in distance between the proximity sensor and the driveshaft changes an output voltage by the proximity sensor.
Data Source
AI summary
A blade position sensing system for a garden tool is provided. The system includes a driveshaft coupled to one or more blades of a blade assembly. The driveshaft is operably coupled to a motor to selectively rotate the driveshaft relative to a threaded shaft and translate the driveshaft along a linear direction. The driveshaft and the threaded shaft are coupled to one another at a threaded interface. Linear translation of the driveshaft angularly translates one or more blades of the blade assembly. A magnet is coupled to the driveshaft. A proximity sensor is positioned in magnetic communication with the driveshaft. A change in distance between the proximity sensor and the driveshaft changes an output voltage by the proximity sensor.