Tread pattern for a vehicle tire

Abstract

Tread for a vehicle tire, wherein a tread groove (1) with a first groove flank (4) and a second groove flank (5) is formed in the tread, wherein a contour (2) of a cross-section (3) of the tread groove (1) perpendicular to a longitudinal extension of the tread groove (1) has no kinks radially below the groove flanks (4, 5). A transition from the first groove flank (4) to a radially lowest point (6) at a groove bottom (7) of the profile groove (1) has within the contour (2) a convex section (8) projecting into the profile groove (1).

Description

[0001] The invention relates to a tread for a vehicle tire, wherein a profile groove having a first groove flank and a second groove flank is formed in the tread, wherein a contour of a cross-section of the profile groove perpendicular to a longitudinal extent of the profile groove has no kinks radially below the groove flanks.

[0002] There are various designs for the flanks of a tread groove. For example, a distinction can be made between the well-known basic shapes of a so-called U-groove with parallel flanks and a so-called V-groove with a groove width that narrows radially inward in a V-shape. Mixed forms with a vertical and an inclined flank are also known. Furthermore, tread grooves with lateral overhangs in the radially upper regions of the groove flanks are also known, which can create narrowed groove openings for stone deflection.

[0003] Various design options are also known for the groove bottom. In special designs, for example, projections can be provided on the groove base to act as stone ejectors. For example, as in the embodiments described in DE 11 2019 004 945 T5, chamfered shapes of the groove contour are often used for this purpose. In general, however, the groove bottom preferably has gentle curves without kinks in order to avoid or at least reduce stress peaks in the groove contour. For a simple groove bottom without additional structures such as stone ejectors, the groove flanks are usually connected to one another by a continuously concave groove bottom. Until now, the prejudice existed that the cross-section of the groove bottom was essentially determined by the angle of inclination of the groove flanks and the groove width.In the case of a narrow U-groove, for example, a semicircular groove cross-section with a radius of curvature of half the groove width is provided as standard.

[0004] A well-known problem with tread grooves is the susceptibility to cracking of the groove walls, particularly at the groove bottom. The invention is based on the object of finding alternative designs for a groove bottom, particularly the cross-section of a groove bottom, in order to positively influence the stability and durability of the tread groove in the area of ​​the groove bottom.

[0005] The stated object is achieved according to the invention in that a transition from the first groove flank to a radially lowest point on a groove bottom of the profile groove within the contour has a convex section projecting into the profile groove.

[0006] The invention recognizes that crack-causing stress at the groove bottom can be better distributed and spread across the groove bottom by the convex section. The invention overcomes the misconception that a larger radius of curvature is always associated with a lower overall susceptibility to cracking. Using the invention, a given stress at the groove bottom can be distributed across many curves, each with a smaller radius of curvature, rather than across a continuous curve with a large radius of curvature, thereby reducing the overall susceptibility to cracking.

[0007] Where the directional designations axial, in the axial direction, radial, in the radial direction, and in the circumferential direction are used, these refer to the tread as intended on a vehicle tire, with the vehicle tire in turn properly attached to a vehicle. The radial direction refers to a direction perpendicular to the rotation axis of the vehicle tire and intersecting the rotation axis. In the radial direction inward refers to the orientation that faces the rotation axis in the radial direction. In the radial direction outward refers to the orientation that faces away from the rotation axis in the radial direction. The circumferential direction refers to the direction of rolling movement around the rotation axis.When the vehicle is moving forward, a position at the front in the circumferential direction on the vehicle tire passes through a minimum distance from the road surface earlier than a position at the rear in the circumferential direction during a 180° rotation of the vehicle tire. The axial direction refers to a direction parallel to the axis of rotation. Pointing axially inward refers to an orientation that is axially facing a tire equatorial plane or a tire equatorial line. The tire equatorial plane is a plane perpendicular to the axis of rotation of the vehicle tire that runs through the center of the axial width of the vehicle tire, with the tire equatorial line running in the tire equatorial plane and on the surface of the vehicle tire. The transverse direction is a direction that consists of components of the radial direction and / or the axial direction.

[0008] In particular, the circumferential direction and the transverse direction can run on a base surface of the vehicle tire. The base surface coincides with the smooth surface that the vehicle tire would have if no small-scale tread elements, such as grooves or radially protruding ribs, were provided. Small-scale tread elements are characterized in at least one of the three dimensions: radial direction, axial direction, and circumferential direction, by a dimension and / or by a radius of curvature that is less than or equal to a maximum tread depth in the vehicle tire. Specifically, the base surface remains physically intact wherever no such tread elements are provided. The retained sections of the base surface can be at least partially intended for contact with a road surface.Where, for example, a groove runs through a tread of a vehicle tire, the base surface continues as an imaginary surface above the groove; where, for example, a radially projecting rib is arranged on the tread, the base surface continues as an imaginary surface below the radially projecting rib.

[0009] All described features relate in particular to a new condition of the tread. The effects achieved by the features of the main claim can be supported and further enhanced by preferred embodiments and configurations.

[0010] Groove flanks are often sections of the walls of a profile groove that run free of kinks and curvatures within the contour of the profile groove's cross-section perpendicular to the longitudinal extent of the profile groove. The groove flanks can extend radially up to the base surface; alternatively, a chamfer can be provided as a transition between a groove flank and the base surface. A boundary between a groove flank and a transition from the groove flank to a radially lowest point on a groove bottom of the profile groove can be defined by the groove flank having no curvature at least immediately radially above the boundary, whereby the transition itself can be curved at least immediately radially below the boundary.Preferably, the contour of the profile groove is continuous, particularly in the area of ​​the boundary between the groove flank and the transition to a radially lowest point on the groove bottom, and can be described consistently using well-defined tangents.

[0011] The transition from the first groove flank to the radially deepest point at the groove bottom of the profile groove can have a concave section on either side of the convex section within the contour. In this way, continuous transitions can be realized from the convex section to the groove flank on the one hand and to the deepest point at the groove bottom on the other, which can be described using well-defined tangents.

[0012] The transition from the first groove flank to the radially deepest point on the groove base of the profile groove can have, within the contour, in addition to the convex section, one or more additional convex sections extending into the profile groove, separated from the convex section by one or more concave sections. By alternating convex and concave sections, for example, a cascade-like transition between the groove flank and groove base can be realized, whereby the stress to be absorbed by the groove base can be advantageously distributed among the partial curvatures in the cascade.

[0013] The convex section can be described, at least in part, by a circular arc with a first radius of curvature. Any concave sections can be described, at least in part, by circular arcs with a second radius of curvature or different second radii of curvature. Any further convex sections can be described, at least in sections, by circular arcs with a third radius of curvature or different third radii of curvature. Preferably, the convex or concave sections are completely described by circular arcs, whereby adjacent convex and concave sections can merge tangentially into one another.

[0014] Any first radius of curvature, any second radii of curvature, and / or any third radii of curvature can be equal to each other in pairs, in groups, or as a whole. This allows for a particularly uniform distribution of stress at the groove bottom across the partial curvatures.

[0015] Suitable radii of curvature for concave sections can range from 0.5 mm to 2.5 mm. Suitable radii of curvature for convex sections can range from 0.5 mm to 5 mm. If a single convex or concave section is described by different radii of curvature, the dimensions refer to the smallest radius of curvature or the largest curvature in the respective section.

[0016] In the preferred embodiments, the contour runs symmetrically to a radial direction. This symmetry allows for a uniform distribution of stress across the groove bottom and groove flanks.

[0017] Two advantageous variants for the design of the groove bottom are proposed: According to a first variant, there is precisely one radially lowest point within the contour at the groove bottom of the tread groove, with the groove bottom being curved along the contour at the radially lowest point. According to this variant, there is therefore no flat groove bottom extending in width, which can be particularly suitable for narrow tread grooves.

[0018] Based on this first variant, a concrete, particularly advantageous design of the transitions between the lowest point on the groove bottom and the groove flanks can be formulated as follows: The curvature in the radially lowest point can be described by a circular arc with a bottom-side radius of curvature, wherein the transition from the first groove flank to the radially lowest point and a transition from the second groove flank to the radially lowest point can each have a first number n of concave sections and a second number m of convex sections. Each convex section can be arranged between two concave sections, where n>1 and m=n-1. According to this embodiment, the concave and convex sections are each described, at least in sections, by a circular arc, wherein the radii of curvature of the convex and concave sections are equal to one another and to the bottom-side radius of curvature.Furthermore, according to this embodiment, the contour runs symmetrically to the radial direction, with the two radially lowest concave sections, i.e., one concave section per transition from the first and second groove flanks, together with the curvature at the radially lowest point, being described by a continuous circular arc. The centers of circular arcs of adjacent concave sections, i.e., those separated from each other by a convex section, are preferably offset from each other in the radial and axial directions by one radius of curvature each.

[0019] According to a second variant, there are several radially deepest points on the groove bottom of the tread groove within the contour, with the groove bottom running flat and straight along the contour at at least one of the radially deepest points. This variant can be particularly suitable for wider tread grooves.

[0020] Based on this second variant, a concrete, particularly advantageous design of the transitions between the deepest points on the groove base and the groove flanks can be formulated as follows: The groove base can run straight and flat within the contour along a certain width, wherein the transition from the first groove flank into this width and a transition from the second groove flank into this width each have a first number n of concave sections and a second number m of convex sections, wherein each convex section is arranged between two concave sections and wherein n>1 and m=n-1.The contour preferably runs symmetrically to the radial direction, with the concave and convex sections being described at least in sections by a circular arc, the radii of curvature of the concave sections being equal to one another and also assuming the same value t as the width of the flat region at the groove base. In this exemplary embodiment, the groove flanks run parallel to the radial direction and, above the transition to the groove base, are spaced from one another by a maximum width. According to a particularly advantageous embodiment of the profile groove, the maximum width of the profile groove is 2 * t * (n + 1). In a profile groove with three concave sections per transition, the width of the rectilinear flat region at the groove base therefore measures 1 / 8 of the groove width, and the concave sections are described by circular arcs with radii of curvature of 1 / 8 of the groove width.The convex sections are preferably defined by circular arcs with suitable radii of curvature, resulting in a continuous contour of the connection between the groove flanks that can be described using well-defined tangents. In this case, the radii of curvature of the convex sections can be equal to each other, but do not have to coincide with the radii of curvature of the concave sections.

[0021] The maximum width of a profile groove can be between 3 mm and 10 mm. For a U-shaped profile groove with flanks running parallel to the radial direction, the maximum width is constant in a radial region above the transitions to the groove base. For a V-shaped groove that widens radially upwards, the maximum groove width is reached in a radially upper section. Any widening of the groove opening due to chamfers is not considered part of the groove width in this context; for example, the maximum groove width of a V-groove with chamfers would therefore be determined radially immediately below the chamfers. The profile groove is preferably a U-groove.

[0022] The tread can be designed such that the contour of the profile groove consistently meets the features described above and / or below along a longitudinal extension section of the profile groove. The longitudinal extension section can be at least a factor of 5, preferably a factor of 10, longer than a maximum width of the profile groove. In one embodiment, the profile groove can have the contour according to the invention along its entire longitudinal extension.

[0023] The profile groove is preferably a circumferential groove.

[0024] The invention also relates to a vehicle tire with a tread according to the above and / or following description. Vehicle tires designed according to the invention are tires of any design, in particular radial tires, and tires of any type, in particular pneumatic vehicle tires for motor vehicles, such as passenger cars, light trucks, or commercial vehicles.

[0025] The invention is described below by way of example with reference to advantageous embodiments in the accompanying drawings. They show: Fig. 1 schematically shows a sectional view of an embodiment of the invention in a sectional plane perpendicular to a longitudinal extension of the profile groove, Fig. 2 schematically and partially a perspective view of an alternative embodiment of a tread according to the invention, Fig. 3 schematically shows a sectional view of a further alternative embodiment of the invention in a sectional plane perpendicular to a longitudinal extension of the profile groove, Fig. 4 schematically shows a sectional view of a further alternative embodiment of the invention in a sectional plane perpendicular to a longitudinal extent of the profile groove.

[0026] Fig. 1 shows the contour 2 of a profile groove 1 in a cross-section 3 perpendicular to a longitudinal extent of the profile groove 1, wherein the radial direction in the plane of the drawing runs from bottom to top. The profile groove comprises a first groove flank 4 and a second groove flank 5, wherein the groove flanks 4, 5 transition to a deepest point 6 on the groove base 7 in a special manner according to the invention. Due to the contour 2 being symmetrical to the radial direction in the exemplary embodiment shown, the special design is described below using the example of the transition from the first groove flank 4: The transition from the first groove flank 4 to the radially deepest point 6 on the groove base 7 of the profile groove 1 has a convex section 8 within the contour 2 that projects into the profile groove 1.The convex section 8 is described by the arc of an imaginary circle shown in dashed lines, which in turn is described by a first radius of curvature 15. Concave sections 12 are arranged tangentially to the convex section 8 on both sides. The concave sections 12 can also be described by arcs of imaginary circles shown in dashed lines, here with second radii of curvature 17. The radially lower of the two concave sections 12 at the transition from the first groove flank 4 to the groove bottom 7 is described by a continuous circular arc with a second radius of curvature 17, together with a curvature at the lowest point 6 of the groove bottom 7 and together with a radially mirror-inverted concave section at the transition from the second groove flank 5 to the groove bottom 7.The second radii of curvature 17 of the concave sections 12 are equal to one another in length and also have the same length as the first radius of curvature 15. The circles of curvature of the concave sections 12 are arranged offset from one another within the cross section in the radial direction and perpendicular to the radial direction by a second radius of curvature 17.

[0027] Fig. 2 shows a perspective view of one of the Fig. 1 very similar alternative embodiment of a profile groove 1. The profile groove is formed in a tread, wherein from the tread in Fig. 2 only shows a block-like section. In the upper part of the image, a groove opening on the base surface of the tread can be seen. In the lower part of the image, a cross-section 3 with a contour 2 can be seen, wherein the contour 2 comprises a first and a second groove flank 4, 5, a convex section 8 and a radially deepest point 6 on the groove base 7. The tread groove 1 is designed with groove flanks 4, 5 running parallel to one another, which are spaced from one another by a maximum width 11. Along a longitudinal extension section 10, the tread groove 1 is designed with a constant cross-section 3. In the example shown, the longitudinal extension section is at least 10 times longer than the maximum width 11 of the tread groove 1.

[0028] Fig. Figure 3 shows the contour 2 of a further alternative embodiment of a profile groove 1 in a cross-section 3 perpendicular to a longitudinal extension of the profile groove 1, wherein the radial direction in the drawing plane runs from bottom to top. In the example shown here, the profile groove 1 has in its contour 2 at the groove bottom 7 a rectilinear flat section with a width 18; within this width 18, any number of, and thus in any case two, radially deepest points 6 can be found on the groove bottom 7. The profile groove according to Fig. 3 is designed symmetrically to the radial direction, so that designations and descriptions on the sides of the first or second groove flank 4, 5 can be transferred to the other side. The contour 2 comprises two concave sections 12 per transition from the first or second groove flank 4, 5 into the flat area of ​​the width 18 on the groove base 7. The concave sections 12 are described by imaginary circular arcs, shown in dashed lines, with mutually identical second radii of curvature 17. The second radii of curvature 17 are also equal in length to the width 18. Between the concave sections 12, a convex section 8 is arranged on each groove side. A constant maximum width 11 radially above the transitions from the groove flanks 4, 5 into the groove base 7 is shown in the upper part of the image of the Fig. 3. In the embodiment shown, the second radii of curvature 17 and the rectilinear flat width 18 at the groove bottom 7 each assume a value of 1 / 6 of the maximum width 11 of the profile groove 1.

[0029] Fig. 4 shows the contour 2 of a further alternative embodiment of a profile groove 1 in a cross-section 3 perpendicular to a longitudinal extension of the profile groove 1, wherein the radial direction in the plane of the drawing runs from bottom to top. As in accordance with the Fig. In the example shown in Figure 3, the profile groove 1 has Fig.4 has in its contour 2 at the groove base 7 a rectilinear, flat section with a width 18; within this width 18, any number of, and therefore in any case two, radially deepest points 6 can be found at the groove base 7. In the embodiment shown, the profile groove is designed symmetrically to the radial direction, so that designations and descriptions on the side of the first or second groove flank 4, 5 can be transferred to the other side. The contour 2 comprises three concave sections 12 per transition from the first or second groove flank 4, 5 into the flat region of width 18 at the groove base 7. The concave sections 12 are described by imaginary circular arcs, shown in dashed lines, with mutually identical second radii of curvature 17. The second radius of curvature 17 is also equal in length to the straight, flat width 18 at the groove bottom 7. Between each two concave sections 12 there is a convex section 8 or 10 on each groove side.A further convex section 13 is arranged. A constant maximum width 11 in the area of ​​the groove flanks 4, 5 is shown in the upper part of the image. In the embodiment shown, the second radii of curvature 17 and the width 18 each assume a value of 1 / 8 of the maximum width 11 of the profile groove 1. List of reference symbols 1 tread groove 2 Contour 3 Cross section 4 first groove flank 5 second groove flank 6 radial lowest point 7 grooved base 8 convex section 10 Longitudinal section 11 maximum width 12 concave section 13 further convex section 15 first radius of curvature 16 second radius of curvature 17 third radius of curvature 18 Width (of a straight flat section at the groove bottom) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 11 2019 004 945 T5

[0003]

Claims

[1] Tread for a vehicle tire, wherein a profile groove (1) with a first groove flank (4) and a second groove flank (5) is formed in the tread, wherein a contour (2) of a cross-section (3) of the profile groove (1) perpendicular to a longitudinal extent of the profile groove (1) has no kinks radially below the groove flanks (4, 5), characterized by that a transition from the first groove flank (4) to a radially lowest point (6) on a groove bottom (7) of the profile groove (1) within the contour (2) has a convex section (8) projecting into the profile groove (1). [2] Tread according to claim 1, characterized by that the transition from the first groove flank (4) to the radially deepest point (6) on the groove bottom (7) of the profile groove (1) within the contour (2) has a concave section (12) on both sides of the convex section (8). [3] Tread according to one of claims 1 or 2, characterized bythat the transition from the first groove flank (4) to the radially deepest point (6) on the groove bottom (7) of the profile groove (1) within the contour (2) has, in addition to the convex section (8), one or more further convex sections (13) projecting into the profile groove (1), separated from the convex section (8) by one or more concave sections (12). [4] Tread according to one of claims 1 to 3, characterized by that the convex section (8) is described at least in sections by a circular arc with a first radius of curvature (15). [5] Tread according to one of claims 2 or 3, characterized by that concave sections (12) are described at least in sections by circular arcs with a second radius of curvature (17). [6] Tread according to claim 3, characterized bythat the one or more further convex sections (13) are described at least in sections by circular arcs with a third radius of curvature. [7] Tread according to one of claims 4 to 6, characterized by that any first radius of curvature (15), any second radii of curvature (17) and / or any third radii of curvature are equal to one another. [8] Tread according to one of claims 1 to 7, characterized by that the contour (2) runs symmetrically to a radial direction. [9] Tread according to one of claims 1 to 8, characterized by that within the contour (2) there is exactly one radially lowest point (6) on the groove bottom (7) of the profile groove (1), wherein the groove bottom (7) is curved along the contour (2) at the radially lowest point (6). [10] Tread according to claim 9, characterized bythat the curvature in the radially deepest point (6) is described by a circular arc with a base-side radius of curvature, wherein the transition from the first groove flank (4) to the radially deepest point (6) has a first number n of concave sections (12) and a second number m of convex sections (8, 13), wherein each convex section is arranged between two concave sections (12), wherein n>1 and m=n-1, wherein the contour (2) runs symmetrically to a radial direction, wherein the concave and convex sections (8, 12) are each described at least in sections by a circular arc, wherein the radii of curvature (15, 17) of the convex and concave sections (8, 12) are equal to one another and to the base-side radius of curvature,wherein radially lowest arranged concave sections (12) of the transition from the first groove flank (4) and a transition from the second groove flank (5) to the radially lowest point (6) are described together with the curvature at the radially lowest point (6) by a continuous circular arc, wherein centers of circular arcs of adjacent concave sections (12) are arranged offset from one another in the radial direction and axial direction by a respective radius of curvature (17). [11] Tread according to one of claims 1 to 8, characterized by that within the contour (2) there are several radially deepest points (6) on the groove bottom (7) of the profile groove (1), wherein the groove bottom (7) runs in a straight line and flat along the contour (2) at least at one of the radially deepest points (6). [12] Tread according to claim 11, characterized bythat the groove base (7) runs straight and flat within the contour (2) along a width (18), wherein the transition from the first groove flank (4) to the width (18) has a first number n of concave sections (12) and a second number m of convex sections (8, 13), wherein each convex section is arranged between two concave sections (12), wherein n>1 and m=n-1, wherein the contour (2) runs symmetrically to a radial direction, wherein the concave and convex sections (8, 12, 13) are described at least in sections by a circular arc, wherein the radii of curvature (17) to the concave sections (12) are equal to one another and to the width (18) and each assume a value t, wherein the groove flanks (4, 5) run parallel to the radial direction and are spaced from one another by a maximum width (11) of the profile groove (1) are spaced, where the following relationship applies: 2 * t * (n + 1) = maximum width (11). [13] Tread according to one of claims 1 to 12, characterized by that a maximum width (11) of the profile groove (1) is between 3 mm and 10 mm. [14] Tread according to one of claims 1 to 13, characterized by that the contour (2) along a longitudinal extension section (10) of the profile groove (1) continuously meets the features of one of claims 1 to 13, wherein the longitudinal extension section (10) is at least a factor of 5, preferably a factor of 10, longer than a maximum width (11) of the profile groove (1). [15] Vehicle tyres having a tread according to any one of claims 1 to 14.

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