Trimmer Head Line Loading Mechanism Without Disassembly
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Solution Overview
Problem
Existing trimmer heads require users to interrupt the connection between the spool and housing to load or unload cutting line, especially when line breakage occurs near the eyelet, making the process cumbersome and time-consuming.
Innovation Solution
The trimmer head features a line receptor channel that allows cutting line to be loaded and unloaded without disconnecting the spool from the housing, using a channel with geometrically opposed open ends and a cam and cam follower mechanism for even winding and distribution, enabling line loading and unloading without splitting the head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the spool is disconnected from the housing to load or unload cutting line, then the line can be loaded or unloaded, but the operation becomes cumbersome and time-consuming
Solution Approach 1:
The spool is divided into two independent halves that can be separated from each other while remaining connected to the housing. This segmentation allows the user to access and manipulate the cutting line on one half of the spool without disconnecting the entire spool assembly from the housing, thereby facilitating easier and faster line loading and unloading operations.
Solution Approach 2:
A cam mechanism acts as an intermediary between the user's manual input and the spool's rotational movement. The cam and cam follower arrangement converts the user's linear pushing motion into controlled rotational movement of the spool, enabling smooth line winding without requiring direct manual manipulation of the spool itself, thus reducing operational complexity and time.
2Ease of repair
If the spool is disconnected from the housing to remove cutting line, then the line can be removed, but the process becomes cumbersome and time-consuming
Solution Approach 1:
The spool is divided into two independent halves that can be separated from each other while remaining connected to the housing. This segmentation allows the user to access and manipulate the cutting line on one half of the spool without disconnecting the entire spool assembly from the housing, thereby facilitating easier and faster line removal operations.
Solution Approach 2:
A cam mechanism acts as an intermediary between the user's manual input and the spool's rotational movement. The cam and cam follower arrangement converts the user's linear pushing motion into controlled rotational movement of the spool, enabling smooth line unwinding and removal without requiring direct manual manipulation of the spool itself, thus reducing operational complexity and time.
3Ease of manufacture
If the cutting line is wound manually onto the spool, then the line can be loaded, but line tangling and crossing occurs which interferes with line payout
Solution Approach 1:
The spool is designed to move dynamically during the line loading process. The cam mechanism creates a reciprocating motion where the spool rotates back and forth in a controlled manner, allowing the line to be wound in one direction while the spool simultaneously shifts position to prevent tangling. This dynamic movement ensures proper line distribution and prevents crossing during the winding operation.
Solution Approach 2:
The line winding process utilizes periodic reciprocating motion of the spool rather than continuous rotation. The cam mechanism causes the spool to oscillate back and forth during winding, creating a periodic action that systematically distributes the line around the spool circumference. This periodic movement prevents line crossing and ensures even distribution, improving line payout reliability.
4Manufacturing precision
If a cam and cam follower mechanism is used for line winding, then even winding and distribution is achieved, but the device complexity increases
Solution Approach 1:
The cam and cam follower mechanism serves multiple functions simultaneously: it controls the reciprocating motion of the spool during winding, ensures even line distribution, prevents line tangling, and facilitates the separation of spool halves. By consolidating these multiple functions into a single mechanism, the overall device complexity is minimized while achieving precise line winding uniformity.
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
Facilitates quick and uniform winding and removal of cutting line without interrupting the spool-housing connection, reducing user effort and time, and allowing line replacement without disassembling the head, even during line breakage.
Implementation Method 1
The simplified pay-out mechanism includes a spring-loaded cam and cam follower arrangement in which the cam follower includes two pairs of diametrically opposed and generally inwardly facing abutment surfaces
Implementation Method 2
The simplified pay-out mechanism includes a spring-loaded cam and cam follower arrangement
Implementation Method 3
This is particularly important in automatic and bump-feed heads where centrifugal force is utilized to pull the new lengths of line from the spool during use as the head is being bumped against the ground
Data Source
AI summary
A trimmer head for use with a length of flexible cutting line in a rotary trimmer comprising a housing operatively connected to the trimmer to effect rotation of the head and a spool for carrying the cutting line thereon. The spool is operatively connected to the housing for rotation therewith and defines a line receptor channel having opposed open ends and traversing the spool. The channel can be aligned with the eyelets in the housing skirt such that cutting line can be inserted therethrough and wrapped about the spool upon relative rotation of the spool and housing without having to interrupt the operative connection therebetween. A central portion of the channel intermediary its open ends is exposed to provide access to the portion of line therein so that line wound about the spool can be pulled from the head without having to interrupt the operative connection therebetween.