Trailer Hitch Force Sensors for Accurate Mass Determination

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Solution Overview

Problem

Existing trailer hitch systems fail to accurately determine and differentiate between various forces acting on the coupling element during towing, such as supporting load, tensile load, and pitching torque, which is crucial for safe operation and weight management of trailers.

Innovation Solution

The system employs multiple force sensors, including strain gauges and inductive force sensors, strategically positioned to measure force components along the X-axis, Z-axis, and torque about the Y-axis, along with an evaluation module that calculates the trailer's mass by accounting for acceleration, temperature, and inclination, using formulas to derive the trailer's mass from force and acceleration signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single force sensor is used to measure support load, then the device complexity is reduced, but the measurement precision of individual force components deteriorates

Engineering Contradiction:
Improvenumber of force sensorsVSAvoidforce component differentiation
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the measurement task into separate force sensors, each dedicated to measuring specific force components (support load, tensile load, shearing load). This segmentation allows each sensor to be optimally positioned and oriented for its specific measurement function, achieving high measurement precision for individual force components while maintaining a manageable overall system complexity through modular sensor placement

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The evaluation device serves multiple functions: it processes signals from multiple force sensors, differentiates between various force components (support load, tensile load, shearing load), compensates for pitching torque effects, and calculates trailer mass. This multi-functional evaluation device consolidates complex processing tasks into a single unit, offsetting the increased sensor complexity with centralized intelligent processing

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

2Measurement precision

If force sensors are positioned to measure multiple force components, then the measurement precision improves, but the device complexity increases

Engineering Contradiction:
Improvevertical load determinationVSAvoidsensor arrangement and evaluation
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Each force sensor is strategically positioned at specific locations on the coupling carrier to optimize its sensitivity to particular force components. The first force sensor measures support load with high precision by being positioned to detect vertical forces, while the second force sensor measures tensile load by being oriented for horizontal force detection. This localized optimization of sensor positions and orientations achieves high measurement precision for each force component

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The evaluation device acts as an intermediary that receives raw signals from multiple force sensors, processes these signals to differentiate between various force components, and compensates for pitching torque effects. This intermediary processing layer transforms complex multi-sensor data into accurate measurements of individual force components, managing the complexity of multi-sensor integration through intelligent signal processing

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If pitching torque is not compensated, then the device complexity is reduced, but the measurement precision of support load deteriorates

Engineering Contradiction:
Improveevaluation algorithmVSAvoidsupport load accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The evaluation device uses feedback from the force sensors to detect pitching torque effects on the support load measurement. By continuously monitoring the forces measured by both sensors and calculating the pitching torque component, the system generates compensatory corrections that are fed back into the support load calculation. This feedback mechanism automatically adjusts for pitching torque variations, maintaining high measurement precision without requiring complex mechanical compensation mechanisms

Inventive Principle:
Principle #23Feedback

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

This approach allows for precise determination of vertical loads and trailer mass, even at low speeds, enhancing safety by accurately accounting for all forces and loads, including those from bicycle carriers, and providing reliable data for driving conditions.

Implementation Method 1

two strain gauges or other force sensors are used, for example inductive force sensors or the like, which can each detect a sum of force components

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

inductive force sensors or the like, which can each detect a sum of force components

Methodology Applied
Scientific EffectInductive sensing: Electromagnetic Induction

Data Source

PatentEP2801488B1Tow hitch with an evaluation device
Publication Date: 2018.04.18 WESTFALIA AUTOMOTIVE
  • EP2801488B1 patent drawingFigure 1~2
  • EP2801488B1 patent drawingFigure 3~4
  • EP2801488B1 patent drawingFigure 5~7

AI summary

A trailer coupling for a towing vehicle (90), comprising a coupling carrier (14) at the free end of which a coupling element (23) for attaching a trailer (92) is arranged and which is arranged on a bracket (11) attached to the towing vehicle (90), comprising an evaluation device (50) for determining at least one force acting on the coupling element (23), and comprising a first force sensor (30a) for detecting first force components acting on the coupling element (23) and outputting a first force signal (33a) representing the first force components.The trailer coupling is provided to have a second force sensor (30b) for detecting second force components acting on the coupling element (23) and outputting a second force signal (33b) representing the second force components, and the evaluation device (50) for determining the force acting on the coupling element (23) on the basis of the first force signal (33a) taking into account the second force signal (33b) in the sense of compensating the first force signal (33a).