Rolling Resistance Measurement in Wheel Service Apparatus
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Solution Overview
Problem
Automotive shops lack the necessary equipment to determine the rolling resistance coefficient of tires, which is crucial for fuel efficiency classification, especially for used tires, as bulky and expensive test equipment is not available for service in these settings.
Innovation Solution
A vehicle wheel service apparatus, such as a wheel balancer or tire changer, equipped with a mounting device, load means, control device, sensor device, and evaluation device, which applies a predetermined load and measures radial and circumferential forces to calculate the rolling resistance coefficient, using force sensors and correction factors to account for differences in load roller diameter and parasitic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bulky and expensive test equipment is used to determine rolling resistance coefficient, then measurement precision is improved, but device complexity and cost increase making it unavailable for automotive shops
Solution Approach 1:
The patent creates a simplified copy of the laboratory test equipment by using a load roller instead of a large flat load surface. This copy replicates the essential measurement function while being compact enough for automotive shop environments. The load roller generates comparable measurement conditions through proper force application and rotational mechanics.
Solution Approach 2:
The patent replaces expensive, complex laboratory equipment with a more affordable load roller system that can be easily manufactured and deployed in automotive shops. The simplified design reduces costs while maintaining sufficient measurement accuracy for practical tire assessment applications.
2Device complexity
If a smaller load roller is used in automotive shops, then device complexity is reduced, but measurement precision deteriorates due to differences in load roller diameter compared to laboratory equipment
Solution Approach 1:
The patent compensates for the smaller load roller diameter by adjusting measurement parameters and applying correction factors. The evaluation device modifies the raw measurement data to account for the geometric differences between shop and laboratory equipment, thereby restoring measurement accuracy despite the size discrepancy.
Solution Approach 2:
The patent implements an evaluation device that processes sensor data and applies corrections based on the known differences between load roller dimensions. This feedback mechanism ensures that the final rolling resistance coefficient reflects accurate tire performance despite measurement conditions differing from laboratory standards.
3Reliability
If force measurements are taken during wheel rotation, then rolling resistance is measured under operating conditions, but parasitic effects from the mounting device and load roller bearings interfere with measurement accuracy
Solution Approach 1:
The patent separates the tire rolling resistance measurement from the parasitic friction effects by using sensor devices that specifically detect forces between the tire and load roller. The evaluation device then extracts the relevant rolling resistance component from the total measured forces, eliminating contamination from bearing friction and mounting device resistance.
Solution Approach 2:
The load roller acts as an intermediary element that transfers the tire's rolling resistance force to the sensor device while minimizing the introduction of parasitic effects. The sensor device mediates between the mechanical forces and the electronic measurement system, enabling accurate detection of the tire's rolling resistance under operating conditions.
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 accurate determination of the rolling resistance coefficient in automotive shops, allowing for fuel efficiency classification of tires, even those that are used, by providing a cost-effective solution that compensates for smaller load rollers and accounts for various parasitic effects, thus improving tire assessment capabilities.
Implementation Method 1
a sensor device arranged to determine forces acting between the peripheral surface of the wheel/tyre assembly and the load means, wherein the forces comprise a first force acting in a radial direction of the wheel/tyre assembly and a second force acting in a circumferential direction of the wheel/tyre assembly
Data Source
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AI summary
A vehicle wheel service apparatus, in particular a wheel balancer or a tyre changer, comprising a load means (26, 126) for applying a predetermined load onto a peripheral surface of a wheel/tyre assembly (14), a sensor device (30) arranged to determine forces acting between the peripheral surface of the wheel/tyre assembly (14) and the load means (26, 126), wherein the forces comprise at least a first force acting in a radial direction of the wheel/tyre assembly (14) and a second force acting in a circumferential direction of the wheel/tyre assembly (14), and an evaluation device arranged to determine a rolling resistance coefficient of the tyre (10) on the basis of the first and second forces.