Resilient tires and wheels – Tires – resilient – Anti-skid devices
Patent
1997-01-02
1998-07-21
Maki, Steven D.
Resilient tires and wheels
Tires, resilient
Anti-skid devices
152DIG3, B60C 1112
Patent
active
057830029
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to the tread of a tire intended to travel on snow-covered, icy or wet roads.
Such a tread is generally provided with elements in relief, ribs or blocks, separated from each other in circumferential direction and/or transverse direction by transverse and/or circumferential grooves and provided with numerous incisions or slits the widths of which are other than zero but far less than the widths of said transverse and circumferential grooves.
Numerous types of incisions have been proposed in order to improve the adherence of the tire to roads of the type in question. As known from French Patent 2 418 719, said incisions may be normal to the surface of the tread or inclined with respect to the direction perpendicular to said surface. Said patent explains what is to be understood by the expression slit or incision, a slit or incision being not only a linear slit in the direction of its depth and/or of its length but also a slit having any other trace, for instance curved, undulated, etc., whatever the cutting plane (longitudinal, transverse or oblique) in question.
French Patent 791 250 shows an example of a slit or incision having an undulated trace on the surface of the tread and even a trace undulated in any cutting plane not containing a generatrix of the undulated surface of the walls of the incision.
French Patent 2 025 124 likewise describes incisions the wall surfaces of which are not flat surfaces but have a relief, although remaining substantially parallel to each other, whatever the trace obtained on any cutting plane. The incision shown in said patent has the feature that it has an undulated surface with circular generatrices, as compared with the incision shown in the preceding patent in which the undulated surface is one with so-called linear generatrices, said generatrices being parallel to each other in both cases.
There can readily be imagined, between these two extremes, incision walls which present a relief for which the generatrices would, for instance, be undulated or zig-zag, the relief then resembling a succession of peaks separated by valleys, the peaks and valleys being undulated, zig-zag or of broken lines in the direction of their lengths.
The incisions described above have an anisotropy factor and their deformations are not identical, whatever the orientations of the forces imposed. There follow from this displacements of the incision walls with respect to each other which differ in accordance with the directions of the forces imposed, which influences not only the rigidity of the elements in relief provided with such incisions but also the performance relative to the behavior of the vehicle equipped with them such as the directional control, the maneuverability of the vehicle, the firmness of the response to the impulses given the steering wheel, and/or else the spiralling upon turning.
SUMMARY OF THE INVENTION
It may be of interest in certain cases to improve said performances, while retaining an incision trace, whether on the surface of the tread or in depth which can be represented by a periodic function and thus obtain optimal properties of the elements in relief of the tread for the entire life of the tire. For this purpose, the invention proposes providing at least certain elements in relief of the tread with at least one incision each of the facing walls of which has a surface in relief formed of protrusions and cavities arranged on opposite sides of a central wall surface, each of said protrusions and cavities having, on said central surface, a quadrilateral base and, spaced from said surface, a vertex, the base of a protrusion being completely surrounded by bases of cavities and, conversely, the ba s e of a cavity being completely surrounded by bases of protrusions, the two surfaces of the two walls respectively being identical so as to form the incision with the desired width.
The protrusions are arranged on one side of the central surface of the wall, while the cavities are arranged on the other side, said cent
REFERENCES:
patent: 2122736 (1938-06-01), Bourdon
patent: 3470404 (1969-09-01), Agerman et al.
patent: 3608602 (1971-09-01), Youngblood
patent: 4566514 (1986-01-01), Mauk et al.
patent: 4598747 (1986-07-01), Flechtner
patent: 4794965 (1989-01-01), Lagnier
patent: 5350001 (1994-09-01), Beckmann et al.
Compagnie Generale des Etablissements Michelin - Michelin & Cie
Maki Steven D.
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