Hub-and-Spoke Trimmer Head Reducing Energy Consumption
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Solution Overview
Problem
Bump-feed type trimmer heads often require disassembly and re-winding when the trimmer line breaks, leading to tangles and inefficiency, and they need high rotational velocity to effectively cut vegetation, which consumes significant energy.
Innovation Solution
A trimmer head design featuring a hub-and-spoke configuration with a spool biased by a spring, where the trimmer line is stored within the hub and extends through pathways in the spokes, preventing withdrawal and allowing for reduced rotational velocity while maintaining cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trimmer line breaks near the housing, then the centrifugal forces are insufficient to maintain the line extending, but this causes the line to be withdrawn into the housing requiring disassembly and re-winding
Solution Approach 1:
The patent extracts the trimmer line from the housing interior and positions it externally along the outer circumference of the hub. This allows the line to remain accessible and prevents it from being withdrawn into the housing when it breaks, eliminating the need for disassembly and re-winding operations.
Solution Approach 2:
The patent pre-positions the trimmer line along the outer circumference of the hub before operation begins. This preliminary arrangement ensures that when the line breaks, it remains in a position where centrifugal forces can effectively maintain it extended, preventing the need for subsequent maintenance intervention.
2Shape
If the trimmer line is positioned close to the axis of rotation, then the structure is compact, but the trimmer head must rotate at very high rotational velocity to achieve sufficient cutting speed
Solution Approach 1:
The patent moves the trimmer line from a position close to the axis of rotation to the outer circumference of the hub, utilizing the radial dimension more effectively. This dimensional change increases the radius of rotation, allowing the line tip to achieve sufficient cutting velocity at lower rotational speeds, thereby reducing energy consumption.
3Productivity
If the trimmer head rotates at high rotational velocity to maintain cutting effectiveness, then the line can cut vegetation effectively, but significant energy is consumed draining the battery or requiring high engine output
Solution Approach 1:
By repositioning the trimmer line to the outer circumference of the hub, the patent increases the effective radius. This allows the same linear cutting velocity to be achieved at lower rotational speeds, directly reducing the energy required to maintain productive cutting operation.
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 prevents trimmer line withdrawal and reduces energy consumption by allowing the trimmer head to operate at lower rotational velocities while maintaining effective cutting performance, minimizing noise and operational energy.
Implementation Method 1
A spring located between the spool and the upper disk body biases the spool into selective engagement with the lower disk body
Implementation Method 2
the centrifugal forces generated during rotation of the trimmer head are not strong enough to maintain the trimmer line extending from the housing
Data Source
AI summary
A trimmer head for use with a handheld lawn maintenance tool is shaped in a hub-and-spoke manner, wherein the trimmer head includes a housing formed of a hub, a circular rim, and a plurality of spokes extending therebetween. A spool is positioned within the hub, and a pair of pieces of trimmer line are inserted into opposing sides of the circular rim through the spokes for winding onto the spool. The trimmer line extends outwardly from the housing at a location spaced away from the hub.