Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2000-02-18
2002-08-27
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209900, C156S110100
Reexamination Certificate
active
06439286
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicular pneumatic tire having a tread that is asymmetrically designed relative to a circumference of the running surface, i.e., the tread includes an outside and an inside region, which are related to the vehicle to which the tire is to be mounted, and each region has a shoulder block row. The tread also includes a center region that is laterally delimited by circumferential grooves belonging to the outside or inside region. Further, transverse grooves in the shoulder block row of the inside region are arranged to extend into the center region.
2. Discussion of Background Information
Different embodiments of tires having asymmetrical tread profiles are known from prior art. Asymmetrical tread profiles are fundamentally those that, relative to the vehicle to which the tire will be mounted, have an inside region and an outside region and the profile structures of these regions fundamentally differ from one another. Indeed, with such a profile design it is possible to deliberately influence and optimize specific tire characteristics, e.g., drainage ability, driving behavior, and tire/road noise produced during tire roll.
However, a vehicular pneumatic tire of the type generally described above is simultaneously tied to the direction of rotation and is discussed in, e.g., EP-A 0 718 124. Here, an optimized tread profile with a separate function is proposed in which, in the outside region, a driving surface portion (positive portion) is at least 75% over a width of 30 to 40% of the tread width. In the inside region, between the tread margin and the circumference center line, the driving surface portion is 55 to 65%. In the center region of the tread, a tread strip is arranged to pass through in the circumferential direction. The tread strip runs along a center circumferential line and is structured by blind grooves that run more or less in continuation of all transverse grooves from the shoulder block row of the outside region. The profile structures in the tread center region are each delimited bilaterally by one wide circumferential groove running straight in the circumferential direction. Tires having this known tread profile have good driving characteristics and good water evacuation capabilities, even at higher speeds.
From DE-A1 38 34 383, a vehicular pneumatic tire, which also has a tread profile tied to the direction of rotation, is disclosed which is not designed asymmetrically. To improve drainage ability, i.e., to improve aquaplaning behavior, and to influence or improve noise development, this tread profile is constructed such that it is essentially composed only of a multiplicity of obliquely-oriented rib profile elements running at an acute angle to the tire circumference center line. The profile channels created by these rib profile elements begin in the region of the tire circumference center line and form an angle there of 15 to 30° with the center line. In the shoulder regions, the profile channels have kinks, so that the angle of the channels to the tire circumference center line formed there is substantially larger. In the tire shoulder regions, between the already-kinked sections of the profile channels, additional profile channels running parallel thereto are provided. With such a tread profile, drainage capability can be improved, but the rib profile elements running at an acute angle to the tire circumference center line over the majority of the tread width, based on their length, are so narrow that, in tires having such a profile design, uneven wear occurs and, contrary to the assumption expressed in the document, a rather unfavorable noise production would occur.
SUMMARY OF THE INVENTION
The present invention provides an asymmetrical tread profile of the type generally described above, which improves drainage ability and favorably influences rolling noise. Moreover, the asymmetrical tread profile of the present invention provides the above advantages while considering the most even possible wear pattern of the tread.
According to the instant invention, the center region of the tread profile can have a width of approximately 25-35% of a tread width, and, e.g., every second transverse groove can be arranged to continue from a shoulder block row of an inside region into the center region as a groove that at least nearly traverses the center region. Grooves in the center region can form an angle with respect to an equator line of a maximum of approximately 30° along at least one-third of their longitudinal extension.
Therefore, tread profiles designed according to the instant invention offer the advantage that, in the center region of the tread, the drainage ability of the tread profile toward the inside region, which is known to be of primary importance, is improved by the grooves at least nearly traversing the center region. Because not all of the transverse grooves have such a continuation from the shoulder block row into the center region, the creation of excessively narrow profile positives in the center region is avoided with the specified acute-angle design of the grooves. This measure is advantageous not only for tread wear but, e.g., also for the rolling noise produced. Specifically, in the center region, abrupt impacts in the inlet and undesired oscillations in the outlet are avoided. Moreover, due to the remaining residual impulses, only frequencies with a half-tone pitch in comparison with the impulses from the shoulder are generated in the tread center region, which results in a mixed frequency that is pleasant to the human ear.
Depending on the path of the grooves in the center region of the tread, alternative embodiments of the invention can be provided in which only every third or every fourth transverse groove continues from the shoulder block row of the inside region into the center region as a groove that at least nearly traverses it the center region.
With tread profiles designed according to the invention, it is therefore possible to orient the grooves in the center region at relatively acute angles to the circumferential direction of the tire. In this regard, an embodiment may be preferable in which such grooves form an angle of less than or equal to approximately 20° to the equator line at their end regions lying by the outside region.
For the rigidity of the tread profile and, therefore, the wear pattern and driving behavior, it may be advantageous when the grooves of the center region end in a space that is a maximum of approximately 10% of the tread width, and preferably a maximum of approximately 5% of the tread width, before the circumferential groove of the outer region which delimits the center region.
Toward the circumferential groove delimiting the center region in the inside region, the angle to the circumferential direction formed by the grooves becomes larger. The angle can be selected such that it is, e.g., between approximately 30-65°, and preferably a maximum of approximately 50°. This design is advantageous for the water drainage ability of the profile.
In that regard, it is also advantageous when the remaining transverse grooves continue from the shoulder block row of the inside region in the center region or up into that region, at least in some cases, as blind grooves that are much shorter than the grooves. The blind grooves preferably end in the region of the equator line, which is also a measure to promote drainage ability.
According to an additional feature of the invention, to avoid a profile rigidity that is unfavorable for wear in the center region of the tread profile, the profile structures in the center region can be divided by additional narrow channels that have a slope in the opposite sense from the grooves and are formed to be less deep than the grooves.
The outside region is designed such that the circumferential groove arranged adjacent to the shoulder block row is constructed as a narrow groove that runs straight in the circumferential direction.
For a good response to steering forces and driving behavior, it can
Baumhöfer Johannes-Josef
Jansen Michael
Wies Burkhard
Continental Aktiengesellschaft
Greenblum & Bernstein P.L.C.
Maki Steven D.
LandOfFree
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