Trailer Coupling Wear Detection Using Pressurized Fluid Cavities

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Solution Overview

Problem

Existing methods for checking the wear of kingpins and coupling bolts in vehicle combinations are unreliable, labor-intensive, and can lead to uncertainty in assessing wear levels, potentially compromising road safety due to improper maintenance or premature replacement.

Innovation Solution

A coupling device with a wear detection system that includes a wear element and a sealed cavity filled with pressurized fluid, where wear causes the fluid to escape when a limit is reached, detected by sensors, allowing continuous and seamless monitoring of wear along the circumferential direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual inspection methods are used to check kingpin wear, then labor costs and time consumption increase, but the reliability and consistency of wear assessment deteriorate due to human error and subjectivity

Engineering Contradiction:
Improveinspection efficiencyVSAvoidwear assessment reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent replaces manual mechanical inspection with an automated sensor-based detection system. Sensors continuously monitor the position of the wear indicator element, eliminating human subjectivity and error while providing objective, repeatable measurements of kingpin wear status.

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

Solution Approach 2:

The wear indicator element automatically indicates wear status without requiring manual measurement. The system self-monitors the kingpin condition through continuous sensor detection, eliminating the need for periodic manual inspections and providing continuous reliability data.

Inventive Principle:
Principle #25Self-service

2Reliability

If manual wear inspection is performed at intervals, then some wear cases may be missed between inspections, but increasing inspection frequency increases labor costs and time consumption

Engineering Contradiction:
Improvewear detection reliabilityVSAvoidinspection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The sensor system provides continuous monitoring of the kingpin wear status throughout operation, eliminating gaps between periodic inspections. The wear indicator element continuously reflects the current wear state, ensuring no wear condition is missed without requiring continuous manual attention.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The wear indicator element proactively signals approaching wear limits before critical wear occurs. The system detects wear trends in advance, allowing preventive maintenance scheduling without requiring frequent manual inspections or risking undetected excessive wear.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If manual inspection methods are used, then assessment subjectivity increases, but automated sensor-based detection requires additional device complexity

Engineering Contradiction:
Improvewear measurement precisionVSAvoiddetection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential wear indication function from complex manual measurement procedures. The wear indicator element and sensor system focus solely on detecting whether wear exceeds the limit, rather than measuring complete wear profiles, simplifying the detection system while maintaining high measurement precision for the critical parameter.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The wear indicator element is positioned at the specific location where wear assessment is most critical. The sensor monitors only the relevant wear indicator position, providing precise measurement of the key parameter without requiring complex comprehensive analysis of the entire kingpin structure.

Inventive Principle:
Principle #3Local quality

4Reliability

If premature kingpin replacement is performed to ensure safety, then road safety may be maintained, but unnecessary costs and downtime increase

Engineering Contradiction:
Improveroad safetyVSAvoidvehicle availability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The sensor system provides continuous feedback on the actual kingpin wear status, enabling data-driven maintenance decisions. The wear indicator element gives objective feedback on whether the kingpin is still within safe operational limits, preventing both premature replacement and operation beyond safe limits.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system transitions from fixed-interval preventive replacement to condition-based maintenance. By continuously monitoring the actual wear parameter through the indicator element and sensor, the system allows the kingpin to remain in service until the specific wear limit is reached, optimizing both safety and vehicle availability.

Inventive Principle:
Principle #35Parameter changes

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 reliable, automatic, and space-efficient wear monitoring, reducing the need for manual inspections and preventing unnecessary replacements, thereby enhancing road safety and extending the service life of the coupling devices.

Implementation Method 1

a cavity (11a, 12a) sealed fluid-tight by the wear element (11c, 12c), wherein the cavity (11a, 12a) is filled with pressurized fluid, wherein wear of the coupling device (1, 2) perpendicular to the longitudinal axis (X) equally or exclusively wears the wear element (11c, 12c), wherein the wear element (11c, 12c) is dimensioned perpendicular to the longitudinal axis (X) such that the fluid can escape through a wear-induced through-opening of the wear element (11c, 12c) when a wear limit of the coupling device (1, 2) is reached at this point of the coupling device (1, 2)

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP4711157A1Coupling device for a trailer
Publication Date: 2026.03.18 RÜHLICKE GMBH
  • EP4711157A1 patent drawingFigure 1~2
  • EP4711157A1 patent drawingFigure 3~4
  • EP4711157A1 patent drawingFigure 5~6

AI summary

Coupling device (1; 2) for a vehicle assembly (3, 4), which extends along a longitudinal axis (X), with a wear detection means comprising: • a wear element (11c, 12c; 21c), which is arranged in and/or on the coupling device (1; 2) in a manner perpendicular to the longitudinal axis (X) such that wear of the coupling device (1; 2) perpendicular to the longitudinal axis (X) equally or exclusively wears the wear element (11c; 12c; 21c), wherein the wear element (11c, 12c; 21c) is arranged in the circumferential direction (U) around the coupling device (1; 2) • a cavity (11a, 11b, 12a, 12b, 14c; 21a, 21b, 24), which extends in the circumferential direction (U) corresponding to the wear element (11c, 12c; 21c) extends, wherein the cavity (11a, 11b, 12a, 12b, 14c; 21a, 21b, 24) is sealed fluid-tight by the wear element (11c, 12c; 21c), and • a pressure sensor (16;26) for detecting the pressure of the fluid in the cavity (11a, 11b, 12a, 12b, 14c; 21a, 21b, 24), wherein the wear element (11c, 12c; 21c) is dimensioned perpendicular to the longitudinal axis (X) such that the fluid can escape through a wear-induced through-opening of the wear element (11c, 12c; 21c) when a wear limit of the coupling device (1; 2) is reached at this point of the coupling device (1; 2).