Sensor Screw Integrating Strain Gauge and Electrical Contacts

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Solution Overview

Problem

Existing sensor installations for measuring forces on kingpins in fifth wheel couplings are complex, costly, and difficult to maintain, with unreliable signal transmission and separate wiring requirements, making them unsuitable for autonomous auxiliary drives.

Innovation Solution

A sensor screw with integrated strain gauges and electrical contacts allows for easy installation and replacement, providing reliable signal transmission without separate wiring, by using a screw design with a measuring device and contact points that connect directly to a socket.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If strain gauges are installed in the bolted connection between the kingpin and the semi-trailer (as in DE 102017 110 520 A1), then force measurement capability is achieved, but the installation complexity and wiring effort increase significantly

Engineering Contradiction:
Improveforce measurement capabilityVSAvoidinstallation complexity and wiring effort
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the structural screw component with the sensing function by integrating strain gauges directly into the screw itself. The screw shank serves as both the mechanical fastening element and the sensing element, merging two previously separate functions (fastening and measurement) into a single integrated component. This eliminates the need for separate measuring washers and complex wiring arrangements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The screw is designed to perform multiple functions simultaneously: it provides mechanical fastening through its thread and head, while also serving as a sensing element through the integrated strain gauges. The electrical connections on the screw head enable signal transmission, making the screw a multi-functional component that combines structural and sensing roles.

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

2Reliability

If separate electrical contacts and wiring are used for sensor signal transmission, then reliable signal transmission can be achieved, but the installation and maintenance difficulty increases

Engineering Contradiction:
Improvesignal transmission reliabilityVSAvoidinstallation and maintenance ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The electrical connections are integrated directly onto the screw head, combining the electrical connectivity function with the mechanical fastening component. This eliminates separate wiring harnesses and connection points, allowing the sensor to be installed and replaced as a single unit while maintaining reliable electrical contact through the integrated connection points on the screw head.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If the kingpin and sensors are designed as separate replaceable parts, then component flexibility is maintained, but the installation and replacement process becomes more complex

Engineering Contradiction:
Improvecomponent replaceabilityVSAvoidinstallation and maintenance complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The screw integrates the sensing function directly into the fastening component, creating a single replaceable unit. When the screw is replaced during kingpin maintenance, the sensor is replaced simultaneously without requiring separate installation or wiring steps, simplifying the overall replacement process while maintaining component flexibility.

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

Enables simple, cost-effective force measurement with reliable signal transmission, allowing for easy maintenance and integration into trailer hitches for autonomous auxiliary drive operation.

Implementation Method 1

a measuring device with a strain gauge arranged along or inside the screw shank, which detects strains of the screw shank in the direction of the screw axis

Methodology Applied
Scientific EffectStrain measurement: Deformation

Data Source

PatentEP4225629B1Screw with strain gauge, screw connection, kingpin and open-end coupling comprising same
Publication Date: 2025.12.03 TRAILER DYNAMICS GMBH
  • EP4225629B1 patent drawingFigure 1
  • EP4225629B1 patent drawingFigure 2
  • EP4225629B1 patent drawingFigure 3

AI summary

The invention relates to a screw (1) with sensor capability, having a screw head (2), having a screw shank (3) which adjoins the screw head (2) along a screw axis (A), and having a thread (4) formed on the screw shank (3). The screw (1) with sensor capability has a measuring device (10) with a strain gauge (11) which is arranged along or in the interior of the screw shank (3) and which detects strains of the screw shank (3) in the direction of the screw axis (A), wherein the measuring device (10) has at least two electrical connections, which are situated as contact points (12, 13) on an outer side (S1) of the screw (1) with sensor capability, and which are in particular arranged such that, when the screw (1) with sensor capability is introduced into a socket (51), said electrical connections come into contact with two correlating electrical contacts (52, 53) of the socket (51).