Sewing Machine Needle Threading Device Tension Control

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Solution Overview

Problem

Existing needle threading devices for sewing machines are complex, unstable in maintaining thread tension, and prone to thread loosening or breakage, with risks of hangnail and fuzz formation during the threading process.

Innovation Solution

A sewing machine equipped with a needle threading device featuring a thread holding tool with a thread holding surface, a thread pressing member, and a thread detachment preventing part that securely holds and guides the thread through the needle hole, ensuring stable tension and easy detachment after threading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complex thread tension mechanism is used to maintain thread tension, then the thread can be kept in a tensioned state for hook catching, but the device complexity increases and the operation becomes troublesome

Engineering Contradiction:

Improvethread tension stabilityVSAvoidmechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of thread tensioning from a complex multi-component mechanism and implements it through a simple distance-based arrangement between the thread holding tool and thread locking part. The tension is achieved by maintaining a large distance between these two points, eliminating the need for complex turning mechanisms and sliding claws.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using an active mechanism to create thread tension through moving parts, the patent inverts the approach by using a passive geometric arrangement where the tension is naturally maintained through the spatial relationship (large distance) between the thread holding tool and thread locking part.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the thread holding force is increased to maintain tension, then the thread remains securely tensioned, but the thread cannot be easily released and may cause hook breakage

Engineering Contradiction:

Improvethread tension maintenanceVSAvoidthread release ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent creates a dynamic thread tension system where the tension force is not fixed but varies with the operational state. During threading, the large distance between holding tool and locking part maintains strong tension. After threading completes, the natural relaxation of the thread allows easy release without requiring active release mechanisms.

Inventive Principle:

Principle #15Dynamics

3Reliability

If existing thread tension mechanisms are used, then thread tension can be applied, but hangnail and fuzz occur in the thread every time it passes the end portion of each mechanism

Engineering Contradiction:

Improvethread tensionVSAvoidthread damage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent removes the problematic end portions of complex tension mechanisms that cause thread damage. By using a simple distance-based tensioning approach without sliding claws, turning parts, or complex guides, the thread passes smoothly without contact points that would create hangnails or fuzz.

Inventive Principle:

Principle #2Taking out (Extraction)

4Device complexity

If a simple thread tensioning method is used, then the device complexity is reduced, but the thread tension becomes unstable and the thread may loosen during operation

Engineering Contradiction:

Improvemechanism simplicityVSAvoidthread tension stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent makes the distance-based thread holding arrangement serve multiple functions simultaneously: it provides stable thread tension, guides the thread through the needle hole, and allows easy release after threading. This multi-functional simple structure eliminates the need for separate mechanisms for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution simplifies the thread tensioning process, maintains secure thread catch by the hook, and prevents thread loosening or breakage, improving work efficiency and reducing the risk of hangnail and fuzz formation.

Implementation Method 1

the thread is detached from a hook part of the hook, based on the frictional force in the needle hole

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS9879367B2Sewing machine equipped with needle threading device

Publication Date: 2018.01.30 JANOME CORP

AI summary

In a sewing machine equipped with a needle threading device, a thread holding tool includes: a thread holding surface part that guides and holds a thread; a thread pressing member that presses and sandwiches together with the thread holding surface part the thread; and a thread detachment preventing part that is provided to cross the thread which is sandwiched between the thread pressing member and the thread holding surface part. When passing the thread through the needle hole, a thread detachment preventing part regulates the thread so that the thread, which is sandwiched between the thread holding surface part and the thread pressing member of the thread holding tool, passes in a predetermined direction without deviating from a thread holding state.