Kingpin Force Sensing in a Fifth-Wheel Coupling Flange Cavity
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Solution Overview
Problem
Existing sensor installations for measuring mechanical reaction forces on fifth-wheel couplings are complicated, costly, and prone to durability issues due to dynamic loads and environmental sensitivity, with strain gages and other sensors being difficult to install and maintain, and not suitable for differential measurement.
Innovation Solution
A measuring device is positioned in a cavity between the mounting flange and the upper end of the pin shaft, protected from mechanical and environmental influences, using contactless capacitive sensors to measure radial forces acting on the kingpin, allowing for easy installation and maintenance, and enabling differential measurement methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are installed directly on the pin shaft or in the vicinity, then measurement of reaction forces is achieved, but durability is considerably reduced due to severe dynamic loads
Solution Approach 1:
The system is divided into two separate parts: the kingpin assembly (which can be replaced) and the sensor system (which remains fixed on the vehicle). The sensor system includes a support structure mounted to the vehicle frame and a sensor that measures displacement of the kingpin relative to the support structure, eliminating the need to mount sensors directly on the dynamically loaded pin shaft.
Solution Approach 2:
A support structure acts as an intermediary between the vehicle frame and the sensor. The support structure provides a stable, fixed mounting point for the sensor, allowing measurement of kingpin reaction forces without subjecting the sensor to severe dynamic loads. The sensor measures displacement between the moving kingpin and the fixed support structure.
2Measurement precision
If strain gages are positioned directly in the fastening screws, then measurement capability is achieved, but installation and maintenance become complicated
Solution Approach 1:
The sensor system is extracted from the kingpin assembly and mounted separately to the vehicle frame. This allows the sensor to remain fixed and accessible for installation and maintenance, while still measuring kingpin reaction forces through displacement measurement. The kingpin can be replaced without affecting the sensor system.
Solution Approach 2:
A support structure serves as an intermediary mounting platform that is easily attachable to the vehicle frame. This support structure provides convenient access for sensor installation and maintenance, while the sensor itself remains fixed and protected, eliminating the complexity of installing sensors directly in fastening screws.
3Measurement precision
If measuring devices are arranged directly on the pin shaft, then measurement capability is achieved, but installation space becomes insufficient
Solution Approach 1:
The measurement system is segmented into a fixed sensor mounted on the vehicle frame and a moving target (the kingpin) whose displacement is measured. This eliminates the need for space-consuming sensor installations on the pin shaft itself, as the sensor remains fixed in an accessible location on the vehicle frame.
Solution Approach 2:
The measurement approach shifts from measuring forces directly on the pin shaft to measuring displacement in the spatial dimension between the kingpin and a fixed support structure. This dimensional change allows the sensor to be mounted in an accessible location on the vehicle frame rather than in the constrained space on the pin shaft.
4Measurement precision
If strain gages are used, then measurement capability is achieved, but temperature sensitivity causes excessive scatter in measured values
Solution Approach 1:
The system replaces strain gages (which are highly temperature-sensitive) with a displacement measurement system using a sensor and support structure. This mechanical substitution eliminates temperature sensitivity issues while maintaining the ability to measure kingpin reaction forces through displacement measurement.
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
The solution provides accurate, durable, and cost-effective measurement of radial forces on the kingpin, insensitive to disturbances, with improved sensitivity and reduced susceptibility to environmental factors, facilitating precise control of trailer dynamics.
Implementation Method 1
contactless capacitive sensors to measure radial forces acting on the kingpin
Data Source
AI summary
The invention relates to a kingpin (10) for a fifth-wheel coupling of a utility vehicle, with a journal shaft (3) which extends along a centre axis (M) and has a journal head (2) at its lower end, wherein the journal shaft (3) has a fastening flange (4) at its upper end remote from the journal head (2), and with a receiving flange (5) which is placed onto the upper end of the journal shaft (3) and is fixed to the fastening flange (4). According to the invention, a measuring device for detecting driving-dynamic reaction forces is provided, wherein the measuring device is arranged in a cavity (15) which is formed in the fixed state between the receiving flange (5) and the upper end of the journal shaft (3).