Secured Screw-Nut Interface for Robotic Mower Height Adjustment
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Solution Overview
Problem
Existing robotic mowers face challenges in maintaining a consistent cutting height due to factors like slippage and friction changes in their height adjustment mechanisms, which can lead to inaccurate cutting heights and potential damage over time.
Innovation Solution
A secured screw-nut interface with a biasing element, such as a spring, is employed to maintain a constant friction and tight fit between the height adjustment screw and nut, ensuring accurate and durable cutting height adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard screw-nut interface is used for height adjustment, then the structure is simple and easy to manufacture, but slippage and friction changes occur leading to inaccurate cutting height
Solution Approach 1:
The biasing element (spring) is pre-installed in the nut to apply continuous preliminary force that maintains constant friction between the screw threads and nut teeth, preventing slippage before it occurs and ensuring accurate cutting height adjustment
Solution Approach 2:
The friction parameter between the screw and nut is changed from variable (prone to slippage) to constant by introducing the biasing element, which maintains steady contact pressure and eliminates height drift during operation
2Duration of action of stationary object
If manual height adjustment is performed without additional components, then the device complexity is low, but wear and slippage increase reducing component lifetime
Solution Approach 1:
The biasing element acts as an intermediary component between the screw and nut, mediating the interaction by maintaining constant contact force, which reduces wear and slippage while extending component lifetime with minimal added complexity
Solution Approach 2:
The spring provides beforehand cushioning by pre-loading the screw-nut interface, preventing excessive wear and slippage before they can occur during normal operation, thereby extending component service life
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 enhances the operator's control over cutting height, reduces slippage and wear, and extends the operational lifetime of the cutting height adjustment components by maintaining consistent friction and tightness between the screw and nut interfaces.
Implementation Method 1
The teeth of the screw engagement nut may be urged toward the threads of the height adjustment screw via the biasing element
Implementation Method 2
The height adjustment screw may rotate to translate the screw engagement nut vertically along the height adjustment screw based on an engagement of teeth on the screw engagement nut with threads of the height adjustment screw
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A robotic mower may include a chassis, a cutting motor driving at least one cutting blade, and a height adjustment assembly. The cutting motor may be mounted on a motor bracket. The motor bracket may provide structural support for the cutting motor at an adjustable level relative to the chassis. The height adjustment assembly may include a biasing element, a screw engagement nut, and a height adjustment screw. The screw engagement nut may be operably coupled to the motor bracket to enable adjustment of a height of the motor bracket via rotation of the height adjustment screw. The height adjustment screw may rotate to translate the screw engagement nut vertically along the height adjustment screw based on an engagement of teeth on the screw engagement nut with threads of the height adjustment screw. The teeth of the screw engagement nut may be urged toward the threads of the height adjustment screw via the biasing element.