Vertical Full-Rotation Shuttle Thread Escape Recess
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Solution Overview
Problem
In sewing machines, when the sewing action stops, the bobbin rotates due to inertia, causing the lower thread to be discharged from the bobbin case and become tangled, leading to thread breakage and incidental looping during the next sewing action.
Innovation Solution
A vertical full rotation shuttle design with a thread escape recess on the inner peripheral surface of the inner shuttle, which increases in depth towards the downstream side, creating a larger clearance for the lower thread to accumulate loosely, guiding it back to the needle location hole and preventing tangling, and includes outwardly and inwardly directed wall portions to ensure proper thread accommodation and prevent interference with the upper thread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clearance between the inner shuttle and bobbin case is reduced to prevent thread interference, then thread tangling is prevented during sewing, but the lower thread cannot be discharged smoothly when the bobbin rotates due to inertia after stopping
Solution Approach 1:
The invention introduces a thread escape recess that extends in the radial direction from the inner peripheral surface of the inner shuttle. This creates a three-dimensional space that the lower thread can enter when discharged, allowing the thread to accumulate in a loosened state without tangling. The recess provides an additional dimensional space (radially outward) that resolves the contradiction between maintaining a narrow clearance and allowing smooth thread discharge.
Solution Approach 2:
The thread escape recess acts as an intermediary space between the narrow clearance and the thread path. When the lower thread is discharged from the bobbin case, it enters the thread escape recess which serves as a buffer zone, allowing the thread to be accommodated in a loosened state without directly interfering with the sewing path or causing tangling.
2Device complexity
If the lower thread is allowed to accumulate in the narrow clearance between the inner shuttle and bobbin case, then the clearance structure is simple, but the thread becomes tangled and causes yarn breakage or incidental looping
Solution Approach 1:
The thread escape recess extends radially outward from the inner peripheral surface of the inner shuttle, creating an additional dimensional space. This allows the lower thread to accumulate in a loosened state within the recess rather than in the narrow radial clearance, preventing tangling while maintaining a relatively simple overall structure.
3Object-affected harmful factors
If the inner shuttle is designed with a larger radial clearance to accommodate discharged thread, then thread tangling is prevented, but the clearance for smooth passage of the lower thread during sewing is reduced
Solution Approach 1:
The invention segments the clearance space into two distinct functional zones: a narrow radial clearance between the outer peripheral portion of the bobbin case and the inner peripheral portion of the inner shuttle for smooth thread passage during sewing, and a thread escape recess extending radially outward for accommodating discharged thread. This segmentation allows each zone to be optimized for its specific function without compromising the other.
Solution Approach 2:
The thread escape recess is provided locally on the inner peripheral surface of the inner shuttle at the downstream side of the needle location hole. This local modification provides the necessary space for thread accumulation only where needed, while maintaining the narrow clearance in other areas for smooth thread passage during the sewing 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 allows for smooth retrieval of the lower thread without tangling, preventing thread breakage and incidental looping by providing a larger clearance and guiding the thread back to the needle location hole, ensuring consistent sewing performance.
Implementation Method 1
a hook portion with a distal end tapered to a downstream side in a direction of rotation of the lower shaft
Data Source
Figure 1
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Figure 3
AI summary
In order to prevent occurrence of thread breakage and incidental looping, a thread escape recess (18) recessed radially outward relative to an imaginary cylindrical surface inscribed in an inner peripheral portion (17) of an inner shuttle (3) is provided adjacent to a downstream side in a direction of rotation (A) of a needle location hole (11).