Recessed Fastener Contact Structure for Accurate Looseness Detection

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Solution Overview

Problem

Existing screw looseness detection methods are prone to erroneous detection due to improper engagement of contact pieces, leading to false alarms when the shaft is not inserted or when the detection member is loosely mounted.

Innovation Solution

A fixing member with a recessed portion and multiple electrically insulated conduction paths, where one path is exposed inside and another outside, allowing a member to press the recessed portion's periphery, ensuring proper contact and reducing false detection by measuring resistance between terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contact pieces are arranged to contact each other when the shaft is inserted, then looseness detection is enabled, but erroneous detection occurs when contact pieces contact even when the shaft is not inserted

Engineering Contradiction:

Improvelooseness detection accuracyVSAvoidengagement state detection precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The contact detection mechanism is segmented into multiple independent contact pieces (first contact piece and second contact piece) with different engagement conditions. The first contact piece detects shaft insertion, while the second contact piece detects proper engagement, allowing the system to distinguish between partial and complete engagement states to prevent erroneous detection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The contact pieces are pre-positioned at specific locations (innermost part and other parts of the recessed portion) to detect engagement at different stages. This preliminary positioning ensures that detection occurs at the correct engagement state before false positives can occur

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a cap-shaped detection member is mounted on the shaft, then engagement detection is possible, but the detection member may contact the nut even when threading is not loosened, causing erroneous detection

Engineering Contradiction:

Improveengagement detection capabilityVSAvoidlooseness detection precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The detection function is extracted from a separate cap-shaped detection member and integrated directly into the nut member structure. The contact pieces are built-in to the nut member, eliminating the need for external mounting that could cause false contact and erroneous detection

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The detection member and nut member are merged into a single integrated component. The contact pieces are formed as part of the nut member's internal structure, ensuring that detection only occurs when the shaft is properly engaged with the nut, eliminating false positives from loose mounting

Inventive Principle:

Principle #5Merging (Combining)

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

This configuration effectively reduces the likelihood of erroneous detection by ensuring accurate engagement state assessment, distinguishing between proper and improper engagement states of the screw and nut.

Implementation Method 1

a plurality of conduction paths being electrically insulated from each other, and including a part of each of the plurality of conduction paths that is exposed at a plurality of positions including a first position in an inside of the recessed portion and in a vicinity of an innermost part and a second position in the inside and in a part other than the vicinity of the innermost part

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11781587B2Engaged member, engaging member, detection device, detection method, and detection program

Publication Date: 2023.10.10 NEC PLATFROMS LTD

AI summary

To reduce the likelihood of erroneous detection resulting from improper engagement of an engaging part with an engaged part, a fixing member is made to have a recess formed therein and is provided with a plurality of conduction paths that are electrically insulated from each other and have portions that are exposed at a plurality of positions including a first position inside the recess and in the vicinity of the innermost part of the recess and a second position inside the recess and not in the vicinity of the innermost part of the recess and other portions that are exposed outside of the recess, and a prescribed member touching the first position and second position can push the area around the opening of the recess.