Flexible Cutting Blade for Grass Trimmers Reducing Motor Torque Spikes
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Solution Overview
Problem
Conventional cutting blades for rotating trimmers often waste power and experience premature wear due to high-impact collisions with obstacles, leading to increased battery drain and safety concerns from shattering fragments.
Innovation Solution
A flexible cutting blade with a tapered, trapezoidal planform and a flexible hinge design that allows bending to reduce tangential forces and increase radial forces, enabling quicker release from obstacles without increasing input energy, and featuring a mass distribution that enhances cutting capability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rigid flail blades are used to cut heavier vegetation, then cutting capability is improved, but the blades shatter upon impact with solid obstacles causing safety concerns and increased vibration
Solution Approach 1:
The patent employs a flexible blade design that can bend and deform upon impact with obstacles, preventing the shattering that occurs with rigid blades. The flexibility allows the blade to absorb impact forces through controlled deformation rather than fracturing, maintaining blade integrity while still cutting vegetation effectively.
Solution Approach 2:
The patent changes the material parameters of the blade, transitioning from rigid hard plastic to a more flexible material composition. This parameter change allows the blade to exhibit both cutting effectiveness and impact resistance by modifying the material's mechanical properties to balance hardness with flexibility.
2Stability of the object's composition
If conventional flexible line blades are used, then blade flexibility is improved, but the blades wrap around obstacles increasing contact time and power consumption
Solution Approach 1:
The patent introduces dynamic characteristics to the blade design, allowing it to change its behavior based on operating conditions. The blade can flex during normal operation but is designed with specific geometric features that prevent excessive wrapping around obstacles, dynamically adjusting its rigidity-f flexibility balance to reduce contact time and power consumption during impact events.
Solution Approach 2:
The patent incorporates curved or tapered geometric features in the blade design that influence how the blade interacts with obstacles. The curvature is designed to reduce wrapping tendency by controlling the blade's contact path with obstacles, allowing quicker release and reducing the duration of impact forces.
3Force
If rigid blades are used to withstand impact stresses, then impact resistance is improved, but the blades become brittle and fracture at the pin or along the blade length
Solution Approach 1:
The patent utilizes composite material construction or a material with combined properties that provide both impact resistance and toughness. The material composition is designed to withstand impact stresses without becoming overly brittle, preventing fracture at the pin or along the blade length while maintaining the ability to absorb impact energy.
4Force
If the blade remains engaged with obstacles longer, then cutting force is maintained, but battery charge power is wasted due to extended impact collision time
Solution Approach 1:
The patent designs the blade to quickly skip off or release from obstacles rather than remaining engaged. The blade's flexible nature and geometric design enable it to rapidly transition from contact to non-contact state, rushing through the impact event with minimal engagement time, thereby reducing the duration of high power consumption and battery drain.
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 blade design reduces power consumption, minimizes wear, and enhances cutting efficiency by reducing motor torque spikes and blade damage, allowing for faster release from obstacles and improved performance in heavy vegetation cutting.
Implementation Method 1
A flexible cutting blade with a tapered, trapezoidal planform and a flexible hinge design that allows bending to reduce tangential forces and increase radial forces
Implementation Method 2
By the conservation of angular momentum (a standard physical law), the angular velocity (ω rad/sec) increases. That is, if an element of mass, m, moves inward from r1 to r2 then mω1r1=mω2r2 or ω2=ω1(r1/r2)
Data Source
AI summary
A cutting blade for a rotating trimmer includes a loading section at a proximal end securable to the rotating trimmer, a flexible hinge section extending from the loading section, and a transition section extending from the flexible hinge section. A cutting section extends from the transition section to a distal end. The transition section and the cutting section are tapered at a taper angle toward the distal end. In some variations, a mass of the transition section is greater than a mass of the cutting section, and a center of gravity based on a mass of the cutting blade may be positioned closer to the loading section than the cutting section.