Burkhard Wies

Reifen im Zielkonflikt zwischen Rollwiderstand und Nassgriff

Der Reifen als alleiniges Bindeglied des Fahrzeugs zur Fahrbahn spielt bekanntermasen eine wesentliche Rolle fur die Sicherheit des Automobils und beeinflusst neben vielen anderen Eigenschaften indirekt auch den Kraftstoffverbrauch. Untersuchungen der Continental AG zeigen die Wirkmechanismen fur Grip und Rollwiderstand sowie Optimierungswege fur die in einem technischen Zielkonflikt stehenden Eigenschaften.

Zusammenwirken von Profil und Laufflächenmischung zur Erzielung eines optimalen Reifenverhaltens

Der Reifen stellt nach wie vor das zentrale Bindeglied zwischen Fahrbahn und Fahrzeug dar. Jegliche Kraftubertragung in allen Fahrsituationen wird durch eine postkartengrose Kontaktflache erzeugt. Dabei sind in den vergangenen Jahren deutliche Fortschritte erzielt worden, um die haufig im krassen Zielkonflikt stehenden Anforderungen zu erfullen. Klassisch werden bei Continental solche Zielkonflikte durch Spezialisierung der Reifen in Relation zwischen Profil und Laufflachenmischung gelost.

3D brush model to predict longitudinal tyre characteristics

ABSTRACT A 3D tyre brush model, which aims to predict the longitudinal tyre characteristic under steady-state conditions by modelling the occurring physical effects in the tyre–road contact patch, is presented. The model includes an analytical method to describe the tyre footprint geometry, the pressure distribution, the slip due to the lateral tyre contour, the slip due to braking or traction and the longitudinal as well as the lateral shear stresses on a flattened tyre. The presented development tool offers a method to investigate different rubber friction data (caused by different tread compounds and/or surface textures) and to analyse its influence on longitudinal tyre characteristics. The tyre design is fixed (same casing, dimension and pattern). The results include the shear stresses as well as the different sliding velocities in the contact patch for different slip conditions. The model was developed for a standard summer pattern design and a standard tyre dimension (205/55R16). It can also be adapted to other tread designs and tyre dimensions. To offer a good comparability between model results and test bench measurements, the surface curvature of an internal test rig is considered.

Tire technology in target conflict of rolling resistance and wet grip

It is a well known fact that tires, as a vehicle’s sole link with the roadway, play a key role in automotive safety and also have an indirect influence on fuel consumption, as well as many other characteristics. Investigations conducted by Continental AG demonstrate the mechanisms for grip and rolling resistance generation and show optimisation methods for these target conflicting properties.

Kraftschluss messungen auf Schnee mit dem Reifen-Innentrommel-Prüfstand

Im Bereich Kraftfahrzeugbau der Universitat Karlsruhe wurde in Zusammenarbeit mit der Continental AG ein Reifen-Schnee-Prufstand entwickelt, der ganzjahrig Tests von Winterreifen auf Kunstschnee ermoglicht. Da hierbei sowohl die Fahrbahn- als auch die Umgebungsbedingungen einstellbar sind, konnen die Reifentests unter reproduzierbaren Bedingungen durchgefuhrt werden. In diesem Beitrag wird unter anderem durch einen Vergleich mit Messungen im Freien das grose Potenzial dieser Prufeinrichtung fur die Entwicklung von Winterreifen aufgezeigt.

Bestandteile Reifen und Räder

In der System Fahrzeug-Strase nimmt der Reifen eine hervorgehobene Rolle ein. Als Bindeglied zwischen Fahrbahn und Fahrzeug ubertragt er alle Krafte und Momente, sein Ubertragungsverhalten geht deutlich in Sicherheit, Fahrverhalten und Komfort des Gesamtfahrzeugs ein. Die dynamischen Fahrzeugeigenschaften werden damit masgeblich durch das Reifenverhalten beeinflusst.

New testing technology to evaluate lateral ice performance of tires

To drive with a vehicle on an icy road surface with standard winter tires (non studded) is due to the low friction potential one of the most critical driving situations appearing in the winter season. To lower the risk for accidents it is necessary to develop tires with increased ice performance. To do so reproducible test methods to evaluate tires potential to transmit forces on ice are necessary. Driving in an ice circle to evaluate the lateral force transmission of tires on ice is a difficult test procedure and its reproducibility can be improved. The newly developed test method is coupling a normal vehicle to a guiding rail and enables the measurement of lateral forces in dependency of the side slip angle of the tires. The new method is highly reproducible and correlating to the ice circle measurement procedure. Not just getting an average lap time to drive in the ice circle, but complete lateral force characteristics is a big benefit of the new test method enabling the tire developers to build up further knowledge about the force transmission of tires on ice, but in future to increase the friction potential even more.

Traction measurements on snow with internal drum test bench

A snow test rig for tires was developed at the automotive department of the Universitat Karlsruhe in collaboration with Continental AG. The test drum makes it possible to test winter tires on artificial snow throughout the year. The fact that both, roadway and environmental conditions, can be adjusted makes it possible to conduct tire tests under reproducible conditions. Drawing on a comparison with outdoor measurements, the present paper presents, inter alia, the enormous potential of this test facility for the development of winter tires.

Interaction of pattern and tread compound to obtain an optimal tire performance

The tire still remains as the central link between road and vehicle. Whatever the driving situation or highway conditions, all power is transmitted via a tire contact patch that is no larger than a postcard. Considerable advances have been made over the years to more closely meet the various, often conflicting requirements. The classic way at Continental of resolving such conflicts of goals is to specialize the tires in relation between their pattern and tread compound.