Overlapping Upper and Lower Blades for Lawn Mower Centrifugal Displacement
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Solution Overview
Problem
Conventional cutter blades for rotary lawn mowers experience displacement due to centrifugal force during rotation, leading to degraded lawn mowing performance and reduced blade strength.
Innovation Solution
A cutter blade design featuring an upper and lower blade configuration where the upper blade has a flat shape with a rising part and the lower blade has a flat shape with a clipping and warping part, overlapping each other to suppress displacement through mutual force application, enhancing lawn mowing performance and reducing stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ribs are provided to improve rigidity, then blade strength is improved, but displacement amount during rotation increases
Solution Approach 1:
The blade is divided into multiple segments including a blade main body, a reinforcement plate, and multiple ribs that are selectively positioned. This segmentation allows the reinforcement plate to provide overall structural support while individual ribs provide localized strengthening, achieving both high strength and low displacement during rotation.
Solution Approach 2:
The reinforcement plate is positioned at specific locations where stress concentration occurs during rotation, such as near the blade tip and at rib connection points. This local reinforcement approach provides maximum strength where needed while minimizing overall blade weight and displacement, rather than uniformly strengthening the entire blade.
2Strength
If outer ends of the blade are displaced upward or downward by centrifugal force, then blade strength is maintained, but lawn mowing performance is degraded
Solution Approach 1:
The reinforcement plate acts as a counterbalancing element that offsets the centrifugal force-induced displacement of the blade outer ends. By strategically positioning the reinforcement plate, the design creates an opposing force that counteracts the downward displacement, maintaining the blade's cutting edge at the correct height for optimal lawn mowing performance.
3Stability of the object's composition
If stress is generated as a result of displacement, then blade strength decreases, but displacement suppression is needed
Solution Approach 1:
The reinforcement plate is pre-positioned to provide cushioning support against centrifugal force-induced stress before the blade enters high-speed rotation. This prior reinforcement prevents excessive displacement and the associated stress generation that would otherwise occur during operation, thereby preserving blade strength throughout the cutting cycle.
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 design effectively minimizes displacement during rotation, improving lawn mowing performance by maintaining blade strength and efficiently generating transportation wind for clipping and transporting grass.
Implementation Method 1
by the influence of the centrifugal force, a force is applied to the upper blade to displace the upper blade downward, and a force is applied to the lower blade to displace the lower blade upward
Data Source
AI summary
A cutter blade for a lawn mower has an upper blade and a lower blade. The upper blade has an upper blade base and an upper outer end positioned above and further radially outward than the upper blade base. The lower blade has a lower blade base and a mowing section positioned below and further radially outward than the lower blade base. The upper blade base overlaps the lower blade base.