Rotary Cutting Blade With Weighted Winglets
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Solution Overview
Problem
Conventional rotary cutting blades in lawn mowers suffer from frictional losses, air resistance, and inefficient cutting due to even weight distribution and flat shape, leading to reduced cutting efficiency and a tendency to tear rather than slice grass.
Innovation Solution
A rotary cutting blade assembly with multiple semicircular blade arms and winglets, where most of the weight is distributed towards the outer half, enhancing rotational inertia and reducing friction and air resistance through a gyroscopic effect, and an airfoil design that promotes efficient cutting and mulching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the blade weight is evenly distributed along the entire length, then the blade structure is simple and easy to manufacture, but the rotational inertia is reduced and cutting efficiency deteriorates
Solution Approach 1:
The blade design transitions from uniform weight distribution to non-uniform distribution by adding weight concentrates at specific locations (outer half and tip regions). This local quality enhancement increases rotational inertia where it matters most for cutting efficiency, while maintaining overall blade simplicity.
Solution Approach 2:
The blade deliberately breaks symmetry in its weight distribution by concentrating mass toward the outer half and tip. This asymmetric weight distribution optimizes rotational inertia for cutting performance while the blade geometry itself remains relatively simple and manufacturable.
2Strength
If the blade is flat and broad, then the blade structure is simple and strong, but air flow resistance and friction increase
Solution Approach 1:
The blade design incorporates curved surfaces and rounded transitions instead of flat surfaces. The curved leading edges, rounded tips, and contoured surfaces reduce air flow resistance and friction while maintaining the structural strength needed for effective cutting.
Solution Approach 2:
The blade geometry parameters are optimized by reducing the overall blade width and adjusting the profile shape. These parameter changes decrease the blade's interaction with air and cut material, reducing friction and air flow resistance while preserving cutting capability.
3Device complexity
If the blade contacts grass at 90 degrees on a 1:1 ratio, then the blade structure is simple, but the cutting action smashes and tears rather than slices
Solution Approach 1:
The blade incorporates localized features such as sharpened leading edges and angled cutting surfaces at specific positions. These local quality enhancements enable the blade to slice grass cleanly rather than smash or tear it, improving cutting quality without significantly complicating the overall blade structure.
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 significantly reduces friction and air resistance, maintaining constant rotational speed and enhancing cutting efficiency by distributing weight for increased inertia and utilizing winglets to create a vortex for progressive cutting, achieving a higher cutting ratio and improved mulching.
Implementation Method 1
most of the blade weight is distributed toward the outer half of a rotary cutting blade to enhance rotational inertia of the blade during cutting
Implementation Method 2
a blade winglet provided on the end of each blade arm to create an airfoil or vortex which promotes the spinning and mulching of cut grass particles
Implementation Method 3
a tapered rear edge to generate an airfoil effect and reduce friction imparted by cut grass or other material
Data Source
AI summary
An improved rotary cutting blade assembly which is characterized by reduced friction and enhanced cutting efficiency is disclosed. The improved rotary cutting blade includes a rotary cutting blade having a blade hub, a plurality of blade arms extending outwardly from the blade hub and a plurality of blade winglets carried by the plurality of blade arms, respectively.