Trimmer Head Line Replacement via Rotating Housing Segments
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Solution Overview
Problem
Existing trimmer heads with cutting lines require complex operations for loading and replacing cutting line stocks, and lack a simple and efficient mechanism for tensioning and unwinding the cutting line.
Innovation Solution
A line-type trimmer head design featuring a housing composed of two portions that can be torsionally and axially coupled, allowing for easy release and rotation, with a spool for winding and unwinding the cutting line, facilitated by resilient members and toothings for secure coupling and easy disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the trimmer head uses a traditional housing structure for storing cutting line, then the structure is simple, but the operation for loading and replacing cutting line becomes complex and time-consuming
Solution Approach 1:
The housing is divided into two separable portions: a first housing portion with exit holes and a second housing portion forming a spool. This segmentation allows the cutting line to be loaded by rotating the second portion relative to the first, enabling easy replacement without disassembling the entire housing. The two portions can be torsionally released and rotated independently to facilitate line loading operations.
Solution Approach 2:
The second housing portion is pre-configured with a spool structure and axial constraining members that automatically engage with the first housing portion. When the two portions are assembled, the spool is already positioned to receive and wind the cutting line, and the constraining members are ready to secure the line in place, eliminating the need for complex loading procedures.
2Ease of operation
If the housing portions are permanently coupled, then the structure is stable, but the cutting line cannot be easily replaced without opening the trimmer head
Solution Approach 1:
The coupling between the two housing portions is made dynamic rather than permanent. The axial constraining members allow the portions to be torsionally released from each other, enabling rotation of the second portion relative to the first. This dynamic coupling maintains stability during normal operation while allowing easy disengagement for line replacement.
Solution Approach 2:
The design allows the cutting line to be discarded and replaced by rotating the second housing portion to unwind the old line and wind new line on the spool. The spool structure is recovered and reused for each new line installation, eliminating the need to discard the entire housing assembly and enabling rapid line replacement.
3Device complexity
If the spool is separate from the housing, then the structure is flexible, but the winding and unwinding operation becomes complex
Solution Approach 1:
The spool is merged with the second housing portion, forming an integral structure. This combination simplifies the winding mechanism by eliminating separate spool mounting requirements and allows the spool to be rotated directly with the housing portion. The merged structure enables easy winding and unwinding of the cutting line through simple rotational motion of the second housing portion relative to the first.
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
Enables simple and fast operations for loading, replacing, and tensioning the cutting line without opening the trimmer head, ensuring continuous cutting performance by allowing easy winding and unwinding of the cutting line.
Implementation Method 1
resilient members and toothings for secure coupling and easy disengagement
Implementation Method 2
the spool is integral with the second housing portion, so that, when the first housing portion and the second housing portion rotate with respect to each other, the cutting line, fastened to the spool and passing through the exit holes provided in the first housing portion, can be wound around, or unwound from, the spool
Implementation Method 3
when the head rotates at high speed around the rotation axis thereof, driven by the drive shaft of the bush cutter, they are tensioned due to the effect of the centrifugal force. Thus, the cutting line, tensioned by the centrifugal force, acts on the vegetation and cuts it.
Data Source
AI summary
A line(F)-type trimmer head (1) is described, configured to rotate around a rotation axis (A-A) and comprising a housing (3) composed of at least one first housing portion (5) and one second housing portion (7), which can be torsionally and axially coupled to one another and which form a volume for a stock of cutting line (F). The second housing portion comprises at least one first passage (31), transverse with respect to the rotation axis of the trimmer head, with a first end and a second end configured and arranged so as to be positioned in correspondence of the two exit holes (9) for the cutting line, so that a cutting line can be inserted through one exit hole and extracted from the other exit hole, passing along the first transverse passage.