Truck Hitch Force Sensor with Temperature Compensation
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Solution Overview
Problem
Existing measuring devices for forces and moments between towing and trailer vehicles lack sensitivity and accuracy, particularly in measuring all three dimensions, and are costly to manufacture due to complex designs and numerous strain-gage rosettes.
Innovation Solution
A measuring device featuring a cruciform carrier with strain-gage rosettes on each measuring arm, connected to an electronic evaluation unit that acquires and evaluates signals in all three directions, incorporating a temperature compensation module to reduce measurement errors, allowing for precise measurement of coupling forces and moments in all three dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gages are oriented in a single measuring direction on measuring arms, then the device structure is simple, but only a part of the actual strain can be measured resulting in limited accuracy
Solution Approach 1:
The patent applies strain-gage rosettes that measure strain in multiple directions (adding dimensional measurement capability) rather than single-direction gages. This allows complete strain state measurement in two dimensions on each measuring arm, resolving the contradiction by measuring all strain components without requiring three separate single-direction gages per arm.
Solution Approach 2:
The strain-gage rosette serves multiple measurement functions simultaneously - it measures strain in multiple orientations and enables calculation of all strain components (normal and shear strains) from a single device installation. This multi-functionality achieves complete strain measurement while maintaining relatively simple device structure.
2Measurement precision
If numerous strain-gage rosettes are arranged on both sides and edges of the flange plate to measure all force components, then measurement completeness is improved, but the number of grooves, slots and bores increases making manufacture and installation elaborate and costly
Solution Approach 1:
The patent uses a three-dimensional measuring cross structure with four measuring arms extending in different spatial directions. This 3D arrangement allows measurement of forces in all three spatial dimensions using only four measuring arms with rosettes, eliminating the need for numerous rosettes on both sides and edges of a plate structure.
Solution Approach 2:
The measuring device is segmented into four distinct measuring arms arranged radially, each independently measuring strain in its specific direction. This segmentation allows each arm to be optimized for its measurement function and simplifies the overall structure compared to a solid plate requiring multiple grooves and slots.
3Reliability
If mechanical components of the hitching mechanism are made with high rigidity to ensure secure connection, then connection reliability is improved, but the sensitivity for measuring forces and moments is reduced
Solution Approach 1:
The hitching mechanism is segmented into a rigid outer structure for connection reliability and a separate measuring cross structure with measuring arms for sensitive measurement. This segmentation allows the connection components to maintain high rigidity while the measuring components can exhibit controlled flexibility for sensitivity.
Solution Approach 2:
The measuring cross acts as an intermediary element between the rigid hitching mechanism and the strain gages. It transfers forces from the rigid structure to the sensitive measurement points, enabling measurement of forces in the rigid connection without requiring the connection components themselves to be flexible.
4Adaptability or versatility
If a cruciform carrier with four measuring arms and strain gages is used to measure forces in multiple directions, then measurement capability in multiple directions is improved, but temperature induced measurement errors increase
Solution Approach 1:
Temperature compensation strain gages are installed in addition to the measuring strain gages. These compensation gages provide feedback on temperature-induced strain changes, which are then used to correct the measurements from the measuring arms, eliminating temperature errors from the final force measurements.
Solution Approach 2:
Temperature compensation strain gages serve as intermediary elements that measure only temperature effects. Their output is used as a correction factor for the main measuring gages, separating the temperature influence from the force measurement and allowing accurate multi-directional force measurement despite temperature variations.
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 device provides high precision and temporal resolution for measuring coupling forces and moments, enhancing vehicle dynamics control and driver-assistance systems by accurately detecting forces and moments in real-time, reducing manufacturing costs and complexity.
Implementation Method 1
A sensor unit, in particular formed by a strain-gage rosette (9, 10, 11, 12) which is arranged on each measuring arm (3a, 3b, 3c, 3d), senses a force-induced and/or moment-induced deformation of each measuring arm (3a, 3b, 3c, 3d)
Implementation Method 2
The temperature compensation module is designed to reduce a temperature induced measurement error of the measuring device (1.1 - 1.6)
Data Source
Figure 1~2
Figure 3a
Figure 4~6
AI summary
The invention relates to a measuring device for measuring forces and/or moments between a towing vehicle and a trailer vehicle of a vehicle combination, with a carrier which exhibits several measuring arms and which is capable of being arranged on and connected to a hitching mechanism for coupling the towing vehicle with the trailer vehicle, a sensor unit sensing a force-induced and/or moment-induced deformation of each of the measuring arms, an electronic measured-data acquisition and evaluation unit which is electrically connected or capable of being connected to the sensor unit and which is designed to acquire and evaluate electrical signals of the sensor unit in all three directions in space, brought about by force-induced and/or moment-induced deformations of the hitching mechanism. The measuring device comprises a temperature compensation module that reduces temperature induced measurement errors.