Trimmer Head Spool With Through-Line Channel
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Solution Overview
Problem
Existing trimmer heads require the spool to be separated from the housing for loading and unloading cutting line, which is time-consuming and prone to tangling, especially when line breakage occurs near the eyelet during use.
Innovation Solution
A spool construction with a line receptor channel that traverses the spool, allowing line loading and unloading without disconnecting from the housing, and molded in two sections to reduce material usage and fabrication issues, ensuring a smooth interior channel surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the spool is separated from the housing for line loading and unloading, then the line can be accessed and replaced, but the operation becomes time-consuming and complex
Solution Approach 1:
The line receptor channel is nested within the spool structure itself, allowing the line to be accessed and manipulated through an opening in the spool while remaining connected to the housing. This eliminates the need to separate the spool from the housing for line replacement, resolving the contradiction between ease of operation and time loss.
Solution Approach 2:
The line receptor channel acts as an intermediary structure that provides direct access to the line within the spool. By incorporating this channel with an opening in the spool, the system allows line loading and unloading operations to be performed without disconnecting the spool from the housing, thus saving time while maintaining operational simplicity.
2Ease of repair
If the spool is separated from the housing for line replacement, then the line can be replaced, but the device complexity increases
Solution Approach 1:
The line receptor channel is integrated as part of the spool structure, nested within the spool body. This integration means that the line can be accessed and replaced through the channel opening without requiring separation of the spool from the housing, thereby maintaining device simplicity while enabling easy line replacement.
Solution Approach 2:
The line receptor channel and spool structure are merged into a single integrated component. This merging eliminates the need for additional separation mechanisms or complex assembly steps for line replacement, reducing device complexity while maintaining ease of repair.
3Strength
If material is used to form a complete spool structure, then the spool is durable, but material usage increases and fabrication issues arise
Solution Approach 1:
The spool structure is segmented by incorporating a line receptor channel with an opening, creating a localized access point rather than a complete enclosed structure. This segmentation allows material to be used more efficiently, reducing overall material consumption while maintaining the structural integrity and durability of the spool where needed.
Solution Approach 2:
The spool structure applies different qualities to different regions: the main body maintains full material density for strength and durability, while the line receptor channel area incorporates an opening to reduce material usage. This local differentiation optimizes the balance between durability and material efficiency.
4Ease of manufacture
If the spool is molded in one piece, then the structure is simple, but the interior channel surface may have fabrication defects
Solution Approach 1:
The line receptor channel is nested within the spool structure with an opening that provides access to the interior. This nested design with an opening facilitates better material flow and reduces trapped air or defects during molding, improving interior channel surface quality while maintaining manufacturing simplicity.
Solution Approach 2:
The spool is molded as a single piece with an integrated line receptor channel opening. This segmentation approach allows the molding process to proceed in one operation (maintaining ease of manufacture) while the opening in the channel facilitates better material distribution and reduces fabrication defects in the interior surface.
Data Source
AI summary
An improved spool construction for carrying a length of cutting line in a trimmer head housing on a flexible line rotary trimmer wherein the spool comprises separately molded upper and lower sections of single piece construction that are pressed together in a snap fitment to define a cylindrical body portion, at least one flange projecting radially therefrom and a line receptor channel having a smooth interior surface that traverses the spool and communicates opposed open outer channel ends in the flange that are radially alignable with opposed line openings in a housing skirt, with an open channel portion in a lower spool surface to provide access to the channel intermediary of the open channel ends with the spool operatively connected to the housing for line loading and replacement without having to interrupt the operative connection between the spool and the housing.