Trimmer Line Spool Slot Design for Compact Winding Volume
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Solution Overview
Problem
Trimmer line cutting heads with large spool sizes for increased winding volume result in a higher cutting height, making it difficult to maintain effective grass cutting due to the enlarged distance from the trimmer line exit to the housing, leading to impaired cutting functionality and frequent line replacement.
Innovation Solution
The rotational stop is integrated into the spool wall as a slot, allowing for a compact design without a raised portion, enabling better force transmission and moment transmission while maintaining a high winding volume, thus reducing the size of the trimmer line spool and cutting head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the trimmer line spool is designed with a large winding volume to reduce frequent line replacement, then the winding volume increases, but the cutting height increases and cutting functionality deteriorates
Solution Approach 1:
The patent transitions from a conventional axial configuration to a radial configuration of the spool wall. By forming the rotational stop as a slot in the spool wall and using a raised portion at the housing to engage this slot, the mechanism achieves rotational stopping functionality in a radial dimension rather than requiring axial extension. This dimensional change allows the spool to maintain a compact axial length while providing sufficient winding volume through radial depth, thereby resolving the contradiction between winding volume and cutting height.
2Reliability
If the rotational stop is formed as a separate component to limit spool rotation, then the rotational limitation function is achieved, but the device complexity increases
Solution Approach 1:
The patent merges the rotational stop function directly into the spool wall structure by forming a slot in the spool wall that engages with a raised portion on the housing. This integration eliminates the need for separate rotational stop components, reducing device complexity while maintaining reliable rotational limitation functionality. The slot in the spool wall and the raised portion on the housing work together as a unified mechanism to prevent over-rotation of the spool during indexing device 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
This configuration allows for a compact trimmer line cutting head with a high winding volume, ensuring effective cutting functionality and reducing the need for frequent line replacements by maintaining the desired cutting height and operational strength.
Implementation Method 1
A spring element is provided and the trimmer line spool is pretensioned by the spring element into an operating position of the trimmer line cutting head
Data Source
AI summary
A trimmer line cutting head has a trimmer line spool rotatably supported about an axis of rotation and disposed slidably between housing and housing cover along the axis of rotation. A spring element pretensions the trimmer line spool in an operating position of the trimmer line cutting head. An indexing device has a terminal stop connecting the trimmer line spool in the operating position to the housing in fixed connection for common rotation of trimmer line spool and housing. By applying an actuating force to the indexing device, the trimmer line spool is adjustable from the operating position axially into an inoperative state of the trimmer line cutting head for paying out trimmer line. The indexing device has a rotational stop formed in a slot in a wall of the trimmer line spool and limiting rotation of the trimmer line spool relative to the housing in the inoperative state.