Tread pattern for a vehicle tire and vehicle tires suitable for winter use

Abstract

Tread for a vehicle tire, wherein at least one transverse or oblique groove with a first groove flank and a second groove flank is formed in the tread, wherein at least on this first groove flank a projection is formed. The projection is positioned with a radially outer end at a distance of between 5% and 30% of the depth of the transverse or oblique groove from a radially outer base surface of the tread.

Description

[0001] The invention relates to a tread for a vehicle tire, wherein at least one transverse or oblique groove with a first groove flank and a second groove flank is formed in the tread, wherein a projection is formed at least on this first groove flank.

[0002] With regard to the winter suitability of a tire tread, two mechanisms are worth highlighting. Firstly, beneficial snow-on-snow friction can develop between the snow held in the tread and the snow cover on the road. Secondly, beneficial milling behavior can come into play, which can occur particularly at the leading edges of tread blocks when they rotate into a ground contact patch. It is often not possible to ensure that both mechanisms work at a high level. This is particularly true for an operating condition in which the vehicle tire spins in the snow: In this case, snow, particularly in normal transverse grooves, is compacted and stiffened to such an extent that it can no longer be released. This in turn means that the leading edge of an adjacent tread block is so blocked with snow that it has no or at least a greatly reduced milling behavior.

[0003] Examples are known from the prior art according to which the accumulation of snow in a tread groove is to be promoted in order to enable snow-on-snow friction, and also examples which are to be used to facilitate the release of snow from a tread groove. CN 12111219 C describes a vehicle tire with a tread comprising a plurality of blocks defined between at least two circumferential grooves and two transverse grooves connecting the circumferential grooves, wherein each block has an edge on the tread which projects into a transverse groove so that a gap to a wall of the transverse groove is defined. This is intended to promote the accumulation of snow and ice in the transverse groove. JP 2005324685 A describes an all-season tire in which a plurality of projections are formed on the wall of a transverse groove and wherein a recessed groove is formed on an underside of the wall along a longitudinal extent of the transverse groove.This combination is intended to achieve improved snow suitability with both improved snow column shear force and improved snow removal without impairing driving characteristics on dry roads.

[0004] The invention is based on the object of creating a tread for a vehicle tire or a vehicle tire with improved snow performance, wherein in particular an advantageous compromise between good snow-snow friction and strong milling behavior is to be achieved.

[0005] The stated object is achieved according to the invention in that the projection is arranged with a radially outer end at a distance between 5% and 30% of a depth of the transverse or oblique groove from a radially outer base surface of the tread.

[0006] The invention recognizes that for good milling performance, it may be sufficient to clear snow from the radially uppermost section of a tread groove. The projection arranged according to the invention is suitable for separating a layer of snow located radially above the projection from a snow reservoir located radially below the projection in the tread groove. The upper layer of snow can then fall out of the tread groove, exposing the tread block edges adjacent to the tread groove to mill into a wintry surface and thus increase traction.At the same time, a snow reservoir is maintained radially below the projection, so that the tread groove, after the tread block edge, which is initially exposed when entering the ground contact area, has been able to develop a beneficial milling effect, can completely fill with snow again in order to ensure beneficial snow-snow friction as it continues to pass through the ground contact area.

[0007] Where the direction 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 or the vehicle tire as intended on a vehicle and the rolling movement it performs. Here, the radial direction refers to a direction perpendicular to the axis of rotation of the vehicle tire and intersecting the axis of rotation. In the radial direction inward refers to the orientation that faces the axis of rotation in the radial direction. In the radial direction outward refers to the orientation that faces away from the axis of rotation in the radial direction. The circumferential direction refers to the direction of a rolling movement around the axis of rotation.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 equator, a tire equator plane or a tire equator line. The tire equator 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 equator line running in the tire equator 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 extend along a base surface of the tread. The base surface coincides with the smooth surface the tread would have if no small-scale tread elements, such as grooves or snow edges, 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 smaller than a maximum tread depth in the vehicle tire. The base surface remains physically intact wherever no such tread elements are provided.

[0009] The resulting sections of the base surface can be at least partially intended for contact with a road surface and coincide there with a tread of the tread. 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 snow edge is located on the tread, the base surface continues as an imaginary surface below the snow edge.

[0010] 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.

[0011] The distance between the radially outer end of the protrusion and the base surface of the tread is to be determined perpendicular to the base surface. In a preferred embodiment, the protrusion is arranged with a radially outer end at a distance of between 1 mm and 3 mm from the base surface of the tread. In this radial region, a particularly good compromise can be achieved between a snow-free upper radial region for good milling behavior and a snow-filled lower radial region as a reservoir for snow-on-snow friction.

[0012] The projection may be raised between 0.3 mm and 1.5 mm, preferably between 0.5 mm and 1.0 mm, above the first groove flank. This distance may be measured perpendicular to an imaginary surface that, in the absence of the projection, would be located on the first groove flank instead of the projection.

[0013] The radially outer end of the projection and a radially inner end of the projection can be spaced apart by between 0.6 mm and 3 mm, preferably between 1 mm and 2 mm. Preferably, the radially outer end and the radially inner end of the projection are located at points of contact with the first groove flank or at the radial ends of the imaginary surface which, in the absence of the projection, would lie on the first groove flank instead of the projection. If the first groove flank runs in the radial direction, as would be the case with a U-groove, for example, the distance between the radially inner and outer ends of the projection is measured along the radial direction. If the first groove flank runs at an angle to the radial direction, as would be the case with a V-groove, for example, the distance is to be determined along a correspondingly inclined direction.

[0014] The projection can be viewed in a sectional plane spanning the radial direction and a further direction perpendicular to the longitudinal direction of the transverse or oblique groove. In such a cross-section, the projection can be described by a convex curvature pointing away from the first groove flank and into the tread groove. Furthermore, the cross-section of the projection can be kink-free, i.e., can be described continuously by well-defined tangents. Alternatively, the cross-section can have kinks, which in practice can be rounded with radii of curvature common in tire production. The cross-section of the projection can take on the shape of a circular arc and, in particular, protrude semicircularly from the first groove flank. Alternatively, more complex shapes are conceivable, according to which the projection can be shaped differently, particularly radially downwards and radially upwards, and can be asymmetrical in cross-section.

[0015] In a preferred embodiment, no further projections are formed on the first groove flank radially below the projection. This creates a clear division into a region arranged radially below and a region arranged radially above the projection, which in turn can result in a correspondingly effective separation of snow accumulated in the tread groove.

[0016] A transition that increases the groove volume can be formed between the second groove flank and the tread of the tread. This increases the groove volume compared to a transverse or oblique groove without such a transition. In particular, a groove width in a radial region of the transition can be increased compared to a groove width that would be present without such a transition. In this way, the hold of snow trapped in the tread groove at the radial height of the transition can be reduced, thus promoting the release of snow from the groove. The transition can be designed, in particular, as a chamfer or a snow pocket.

[0017] A chamfer, viewed in a cross-sectional plane spanned by the radial direction and another direction perpendicular to the longitudinal extension of the transverse or oblique groove, can be described by a straight line angled relative to the radial direction, which ends at one end in the tread and at the other end in the second groove flank. In a conventional manner, the angle of the chamfer relative to the radial direction can be, for example, between 30° and 60°.

[0018] A snow pocket can be described in cross-section, for example, by a concave arc, wherein the concave arc can be open radially upwards and towards the first groove flank. The concave arc can further be delimited opposite the transverse or diagonal groove by a radially upwardly projecting wall, so that at the bottom of the snow pocket, between the tread and the transverse or diagonal groove, a radially upwardly open groove is formed, which can be filled with snow and contribute to advantageous snow-on-snow friction. The radially upwardly projecting wall preferably does not extend radially to the base surface but is further preferably limited to a radial region below the radially outer end of the projection.

[0019] Alternatively, convex arcs and / or combinations of convex, concave and straight sections are also conceivable for the cross-section of a transition between the second groove flank and the tread, which increases the groove volume.

[0020] The transition between the second groove flank and the running surface, which increases the groove volume, is preferably arranged directly opposite or at least overlapping the projection, viewed along a longitudinal extent of the transverse or oblique groove. A radial boundary between the transition and the second groove flank is preferably radially no more than 20% of the depth of the transverse or oblique groove from the radially inner and radially outer ends of the projection. This means that the radial boundary is arranged a maximum of 20% of the groove depth from the one of the two radial ends of the projection that is further away from the radial boundary. The boundary between the transition and the second groove flank is preferably arranged at a radial height that lies between the radially outer end of the projection and the radially inner end of the projection.In this way, a layer of snow trapped radially above the protrusion in the tread groove is limited by the transition on the second groove flank. Overall, the snow layer on the first groove flank is separated from a radially lower snow reservoir by the protrusion, while simultaneously having reduced grip on the second groove flank. With such a coordinated design of both groove flanks, a layer of snow of the desired radial thickness can be specifically released from the tread groove.

[0021] In a preferred embodiment, the first groove flank is arranged on an incoming block edge. When a vehicle tire comprising a tread block travels forward, an incoming block edge enters a ground contact patch earlier than a trailing block edge. In this case, the projection on the first groove flank points forward in the circumferential direction and, in other words, in the direction in which the first groove flank rotates into the ground contact patch. Thus, the projection can act on snow accumulated in the tread groove in the direction of rolling movement and mechanically separate it particularly effectively into two radial areas. Additionally, a projection can also be arranged on a second groove flank, wherein the second groove flank is arranged on a outgoing block edge.This allows the projection to act on a snow reservoir when reversing and / or braking in the manner described above.

[0022] The projection preferably extends over a continuous section of at least 5 mm along the first groove flank. By extending a continuous section along the longitudinal extension, the effect of the projection can be appropriately deployed, and snow can be released over the entire continuous section of the tread groove.

[0023] The projection can extend at a constant radial level along the longitudinal extent of the profile groove. This allows for a particularly advantageous radial arrangement over the entire longitudinal extent of the projection.

[0024] It may be advantageous to design the radial boundary between the transition that increases the groove volume and the second groove flank so that it can vary in its radial height along the longitudinal extent of the transverse or oblique groove. In this case, the radial boundary between the transition and the second groove flank on one side and the projection on the other side can change qualitatively and preferably also quantitatively in their respective radial levels along the longitudinal extent of the transverse or oblique groove. A qualitatively consistent change occurs, for example, when the radial boundary and the projection both shift to a higher radial level or both shift to a lower radial level along the longitudinal extent of the profile groove.A quantitatively consistent change occurs when the displacement of the radial level is identical for each longitudinal extension between the radial boundary and the projection. A change in the radial level can also be sinusoidal or zigzag-shaped, for example. In this case, a qualitatively consistent change would occur if the phase is consistent, and a quantitatively consistent change would occur if the amplitude is also consistent. By consistently changing the radial levels, the position of the projection can be adapted to a beneficially changing position of the boundary between the transition and the second groove flank, in order to achieve a favorable match between the projection and the transition along the longitudinal extension.

[0025] In addition to the projection, a further projection may extend over a further continuous section along the first groove flank, wherein the sections preferably do not overlap along a longitudinal extent of the transverse or oblique groove. The two sections may be spaced apart from one another by between 1 mm and 5 mm along the longitudinal extent of the transverse or oblique groove. In addition to the projection, several further projections may also extend along the first groove flank. The one further projection(s) are preferably designed according to the features of a projection described above and / or below; further preferably, all projections in the tread are designed identically.By using two or more sections with projections according to the invention, the effect according to the invention can be distributed accordingly over the tread and dosed in a targeted manner in sections: In areas without a projection on a groove flank, more snow can remain in the profile grooves, so that particularly good snow-to-snow friction is achieved here; in areas with a projection, the milling effect of block edges exposed according to the invention can predominate.

[0026] The transverse or diagonal groove can be a diagonal groove running between a first tire shoulder and a tire equator region. This diagonal groove, together with another diagonal groove, can describe a V-shape axially spanning the tread from the first tire shoulder to a second tire shoulder. V-shaped tread patterns are known per se, particularly for winter and all-season tires, with the tip of the V being arranged directly at the tire equator or offset by a few percent of the axial tread width. The use of a projection according to the invention in such a tire tread is suitable because of the general winter suitability shared by the projection and the V pattern.Furthermore, the projection according to some of the embodiments described above and / or below is preferably to be used on a directional vehicle tire, wherein V-shaped groove arrangements are also generally designed for directional use.

[0027] The protrusion can be located in an axially central section of the tread, i.e., a section centered around a tire equator. The axially central section can be defined in an area of ​​50% of the width of the ground contact patch, whereby the ground contact patch can correspond to the statically determined footprint at a load of 70% of the maximum load capacity at an internal pressure of 85%, determined according to ETRTO standards. In this area of ​​the tread, snow compaction in the tread grooves is particularly severe, so that the inventive exposure of block edges can be particularly important.

[0028] The invention also relates to a vehicle tire with a tread as described above and / or below. 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.

[0029] The invention is described below by way of example with reference to advantageous embodiments in the accompanying drawings. They show: Fig. 1 schematically and partially a plan view of an embodiment of a tread according to the invention, Fig. 2 schematically and partially a side sectional view of an embodiment of a vehicle tire according to the invention, Fig. 3 schematically shows an enlarged view of a Fig. 2 shown oblique groove, Fig. 4 schematically shows a sectional view of an alternative embodiment of a profile groove according to the invention, Fig. 5 schematically shows a sectional view of another alternative embodiment of a profile groove according to the invention.

[0030] Fig. Figure 1 shows a highly simplified section of a tread 1, wherein an axial direction in the drawing plane is shown from left to right and a circumferential direction from top to bottom. Three circumferential grooves 2 run axially centrally and axially offset to both sides. Oblique grooves 3 run through the tread 1 in a V-shape from the axial center to the axial outside. Profile blocks 11 are defined between the circumferential grooves 2 and oblique grooves 3. In an axially inner region, between each two circumferential grooves 2, an inventive design of the groove flanks 9, 10 can be provided. This is illustrated by a sectional view according to section plane 7 in Fig. 2, where the section plane 7 is delimited by the dashed line in Fig. 1 and the radial direction perpendicular to the drawing plane.

[0031] Fig. Figure 2 shows a sectional view of a radially lower part of a vehicle tire 4, which rotates along a direction of rotation 5 or in the circumferential direction when a vehicle (not shown) is traveling forward. The vehicle tire 4 rolls on a layer of snow 6 or partially sinks into this layer of snow 6, leaving behind a layer of pressed-in snow 6*. Distributed over the circumference of the vehicle tire 4, cross sections of essentially identical oblique grooves 3 can be seen. The oblique grooves 3 are arranged in a Fig. 1 illustrated tread 1, wherein the tread 1, as known per se, comprises a radially outer layer of the Fig. 2. The oblique grooves 3 fill with snow as they pass through the snow cover 6. With a sufficiently deep snow cover 6, the snow in the oblique grooves 3 can be compacted so that the oblique grooves 3 remain radially filled with snow essentially up to the tread 1* during an entire rotation of the vehicle tire. As a result, in particular the incoming block edges 11* of the tread blocks 11 can be blocked, so that advantageous milling behavior upon entry into the snow cover 6 is eliminated. To solve this problem, according to the invention, projections 8 are provided on the first groove flanks 9 of the oblique grooves 3, as can be seen from FIG. Fig. 3 is explained in more detail.

[0032] This shows Fig. 3 an enlargement of the Fig. 2. A projection 8 is arranged in a radially upper region on a first groove flank 9. A radially outer end 16 of the projection 8 is spaced a few millimeters from the tread 1*. In the exemplary embodiment shown, this distance corresponds to a distance between the radially outer end 16 of the projection 8 and the base surface of the tread 1, because the first groove flank 9 runs in the radial direction in the exemplary embodiment shown. With an inclined groove flank 9, the distance between the radially outer end 16 of the projection 8 and the base surface would have to be measured relative to a position in the base surface at which the tread 1* would be interrupted by the groove, i.e. the base surface would only imaginarily run above the groove 3. In the cross-section shown, the projection 8 takes on the shape of a semicircle extending between the radially outer end 16 and a radially inner end 17 of the projection 8.The projection 8 extends in a rib-like manner over a section along the longitudinal extent of the oblique groove 3, the section being located between two circumferential grooves 2 according to . Fig. 1 can be arranged. On a second groove flank 10 opposite the first groove flank 9, a chamfer 12 is formed as a transition 12 to the tread 1*. A radial boundary 18 between this transition 12 and the second groove flank 10 is arranged at a radial height that is located between the radially outer end 16 of the projection 8 and the radially inner end 17 of the projection 8 and in particular near a point of the projection 9 that is furthest elevated relative to the first groove flank 9. As illustrated by a boundary line drawn transversely through the groove 3 between the projection 8 and a radially lower end of the chamfer 12, the projection 8, supported by the chamfer 12, can be suitable for separating a snow reservoir accumulated in the oblique groove 3. In this case, in particular, a radially outer layer of snow 13 is separated and can be released from the oblique groove 3 (cf.snow layer 13 shown at a distance from the oblique groove 3).

[0033] Fig. 4 shows a sectional view of an alternative embodiment of a tread 1 according to the invention with an alternatively designed transverse or oblique groove 3. The Fig. 4 underlying cutting plane is spanned by the radial direction and a further direction perpendicular to a longitudinal extension of the transverse or oblique groove 3. The first groove flank 9 is very similar to the embodiments according to Fig. 2 and Fig. 3, with a projection 8. In the present embodiment, instead of a chamfer 12, a snow pocket 14 is arranged on the opposite second groove flank 10 as a transition 14 into the tread 1*, wherein the snow pocket 14 is delimited from the groove 3 by a radially upwardly projecting wall 15. A radial boundary 18 between the second groove flank 10 and the snow pocket 14 can be defined where the gradient of the second groove flank 10 begins to decrease.

[0034] Fig. 5 shows a sectional view of a further alternative embodiment of a tread 1 according to the invention with an alternatively designed transverse or oblique groove 3. The Fig. 5 underlying cutting plane is spanned by the radial direction and a further direction perpendicular to a longitudinal extension of the transverse or oblique groove 3. The second groove flank 10 is, similar to the embodiment according to Fig. 4, is equipped with a snow pocket 14. The opposite first groove flank 9 is more inclined relative to the radial direction than the second groove flank 10. A projection 8 arranged on the first groove flank 9 has a partial area running parallel to the radial direction and is connected to the first groove flank 9 in various ways radially upwards and downwards. A projection 8 with a cross section as shown in Fig. The embodiment shown in Figure 5 is particularly stable and can be manufactured particularly well in a correspondingly designed tire mold. List of reference symbols 1 tread 1* Tread 2 circumferential grooves 3 transverse or diagonal groove 4 vehicle tires 5 Direction of rotation 6 Snow cover 6* compressed snow 7 Cutting plane 8 lead 9 first groove flank 10 second groove flank 11 profile block 11* incoming block edge 12 transition (chamfer) increasing the groove volume 13 radial outer layer of snow 14 transition increasing the groove volume (snow pocket) 15 radially upward projecting wall 16 radial outer end of the projection 17 radial inner end of the projection 18 radial boundary from the transition 12, 14 to the second groove flank 9 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] CN 12111219 C

[0003] JP 2005324685 A

[0003]

Claims

[1] Tread (1) for a vehicle tire (4), wherein in the tread (1) at least one transverse or oblique groove (3) with a first groove flank (9) and a second groove flank (10) is formed, wherein a projection (8) is formed at least on the first groove flank (9), characterized by that the projection (8) is arranged with a radially outer end (16) at a distance between 5% and 30% of a depth of the transverse or oblique groove from a radially outer base surface of the tread (1). [2] Tread (1) according to claim 1, characterized by that the projection (8) is arranged with a radially outer end (16) at a distance of between 1 mm and 3 mm from a radially outer base surface of the tread (1). [3] Tread (1) according to one of claims 1 or 2, characterized bythat the projection (8) is raised between 0.3 mm and 1.5 mm, preferably between 0.5 mm and 1.0 mm, relative to the first groove flank (9). [4] Tread (1) according to one of claims 1 to 3, characterized by that the radially outer end (16) of the projection and a radially inner end of the projection (8) are spaced apart from each other by between 0.6 mm and 3 mm, preferably between 1 mm and 2 mm. [5] Tread (1) according to one of claims 1 to 4, characterized by that no further projections are formed on the first groove flank (9) radially below the projection (8). [6] Tread (1) according to one of claims 1 to 5, characterized by that a transition (12, 14) increasing the groove volume is formed between the second groove flank (10) and a tread (1*) of the tread (1). [7] Tread (1) according to claim 6, characterized bythat a radial boundary (18) between the transition (12, 14) and the second groove flank (9) is radially not more than 20% of the depth of the transverse or oblique groove (3) away from the radially inner and from the radially outer end (16, 17) of the projection (8). [8] Tread (1) according to one of claims 1 to 7, characterized by that the first groove flank (9) is arranged on an incoming block edge (11*). [9] Tread (1) according to one of claims 1 to 8, characterized by that the projection (8) extends over a continuous section of at least 5 mm along a longitudinal extent of the transverse or oblique groove (3). [10] Tread (1) according to claim 9, characterized by that the projection (8) extends at a constant radial level. [11] Tread (1) according to claim 7 and claim 9, characterized bythat the radial boundary (18) between the transition (12, 14) and the second groove flank (9) on the one side and the projection (8) on the other side change qualitatively and preferably also quantitatively in their respective radial level along the longitudinal extent of the transverse or oblique groove (3). [12] Tread (1) according to one of claims 9 to 11, characterized by that in addition to the projection (8) a further projection extends over a further continuous section along the first groove flank (9), wherein the sections do not overlap along the longitudinal extent of the transverse or oblique groove (3). [13] Tread (1) according to claim 12, characterized by that the two sections are spaced apart from each other by between 1 mm and 5 mm along the longitudinal extent of the transverse or oblique groove. [14] Tread (1) according to one of claims 1 to 13, characterized byin that the transverse or oblique groove (3) is an oblique groove (3) extending between a first tire shoulder and a tire equator region, wherein the oblique groove (3) together with a further oblique groove (3) describes a V-shape axially spanning the tread (1) from the first tire shoulder to a second tire shoulder. [15] Tread (1) according to one of claims 1 to 14, characterized by that the projection (8) is arranged in an axially central section of the tread (1).

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