Overlock Sewing Machine Single Switch Cover Detection

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Solution Overview

Problem

Existing overlock sewing machines require multiple switches to detect the open/closed states of looper and side covers, leading to complex wiring and increased costs, while also having additional covers that complicate the system.

Innovation Solution

An overlock sewing machine design that uses a single switch to detect the open/closed states of both the looper cover and side cover, employing a detection lever and spring mechanism to enable or disable the motor based on the position of these covers, simplifying the structure and reducing the need for multiple switches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple switches are used to detect the open/closed state of looper cover and side cover, then the detection accuracy is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvedetection accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple cover detection functions into a single switch mechanism. The switch is positioned to detect both the looper cover and side cover states simultaneously, eliminating the need for separate switches for each cover while maintaining accurate detection of their open/closed states.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single switch is designed with multi-functional capability to detect the states of multiple covers (looper cover and side cover). This universal detection mechanism allows one component to perform the function of what would traditionally require multiple separate components, reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple switches are used to detect the threading state, then the reliability is improved, but the wiring complexity and cost increase

Engineering Contradiction:
ImprovereliabilityVSAvoidwiring complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the threading state detection function with the cover detection function into a single switch mechanism. The switch detects both cover positions and threading state simultaneously, consolidating multiple detection functions into one component and reducing wiring requirements while maintaining reliable operation.

Inventive Principle:
Principle #5Merging (Combining)

3Device complexity

If a single switch is used to detect multiple cover states, then the device complexity is reduced, but the measurement precision may deteriorate

Engineering Contradiction:
Improvedevice complexityVSAvoiddetection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a detection lever as an intermediary mechanism between the covers and the switch. This lever translates the positional states of multiple covers into distinct switch activation patterns, enabling the single switch to accurately differentiate between various cover configurations (both closed, one open, both open) without sacrificing detection precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3498904B1Overlock sewing machine
Publication Date: 2022.10.26 JANOME CORP
  • EP3498904B1 patent drawingFigure 1
  • EP3498904B1 patent drawingFigure 2
  • EP3498904B1 patent drawingFigure 3(A)~3(B)

AI summary

A single switch is required to detect looper cover and side cover open/closed states and to detect switching of a threading state. With the overlock sewing machine, when a switching mechanism is switched to a threading-enabled state, and the looper cover is closed, the looper cover is slid toward one side in the hinge shaft axial direction so as to operate a detection lever. In the non-operating state, the detection lever is set to an initial position where it does not press an operation protrusion of a switch. When the side cover is closed, and the detection lever is operated, the operation lever is set to an operation-enabled position where it presses the operation protrusion. When the operation lever is operated, and the side cover is opened, the detection lever is set by passing through the operation-enabled to the operation-disabled position where it does not press the operation protrusion.