RFID Sensor Nut for Contactless Bolt Preload Measurement

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Solution Overview

Problem

Existing screw nut technologies lack an efficient and cost-effective method for determining preload force in screw connections, as current methods are often dependent on friction conditions and require mechanical changes or additional energy sources.

Innovation Solution

A screw nut with an integrated sensor module featuring a deformation detection sensor and RFID transponder unit, allowing contactless measurement of preload force through electromagnetic coupling, eliminating the need for external energy sources and minimizing mechanical alterations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional methods are used to determine preload force, then measurement can be achieved, but the measurement is dependent on friction conditions and requires mechanical changes or additional energy sources

Engineering Contradiction:
Improvepreload force determinationVSAvoidmechanical changes and energy sources
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical measurement methods with an RFID-based wireless sensor system. The deformation sensor detects preload force through electrical resistance changes rather than mechanical contact, eliminating dependence on friction conditions and reducing mechanical complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The sensor module utilizes the existing electromagnetic field from the RFID reader to power its operations. The deformation sensor's electrical properties change with mechanical deformation, allowing the system to self-measure without external power sources or additional mechanical components

Inventive Principle:
Principle #25Self-service

2Device complexity

If contactless measurement is implemented using RFID technology, then no additional energy sources are needed, but the system requires electromagnetic coupling infrastructure

Engineering Contradiction:
Improveenergy sourcesVSAvoidelectromagnetic coupling requirement
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The RFID reader serves multiple functions: it provides both the electromagnetic field for wireless communication and the power source for the sensor module. This multi-functionality eliminates the need for separate battery or power supply components in the sensor module

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

Solution Approach 2:

The electromagnetic field acts as an intermediary that transfers both data and energy between the RFID reader and the sensor module. This field-based interaction enables contactless operation while eliminating the need for physical electrical connections or separate power sources

Inventive Principle:
Principle #24Intermediary (Mediator)

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 quick, reliable, and cost-effective determination of preload force in screw connections, independent of friction conditions, with no requirement for additional energy sources or mechanical changes to existing components.

Implementation Method 1

contactless determination of the preload force... by means of radio transmission... electromagnetic coupling

Methodology Applied
Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 2

at least one deformation detection sensor arranged on a base body of the screw nut for detecting a deformation of the base body

Methodology Applied
Scientific EffectStrain gauge effect: Piezoresistive Effect

Data Source

PatentEP3987191B1Screw nut and mounting device
Publication Date: 2023.11.29 MICRO SENSYS
  • EP3987191B1 patent drawingFigure 1~2
  • EP3987191B1 patent drawingFigure 3
  • EP3987191B1 patent drawingFigure 4

AI summary

The invention relates to a screw nut (1) with a sensor module (5) for determining a pre-tensioning force of a screw connection, wherein the sensor module (5) comprises at least one deformation detecting sensor (7), which is arranged on a main body (6) of the screw nut (1) and is intended for detecting a deformation of the main body (6) of the screw nut (1), and an RFID transponder unit (8), and wherein a printed circuit board (9) of the sensor module (5), on which an antenna (10) of the RFID transponder unit (8) and an electronic circuit of the sensor module (5) are formed and which is coupled in an electrically conductive manner to the at least one deformation detection sensor (7), is arranged on an end face (11) of the main body (6). The invention also relates to a mounting device (2).