VEHICLE AIR TIRES

Description

[0001] The invention relates to a pneumatic vehicle tire, in particular a commercial vehicle tire, with a tread having at least one tread rib running circumferentially, which is delimited on at least one side by a circumferential groove designed to the tread depth and which is traversed by incisions which, in plan view, run at least in groups parallel to one another and to the axial direction at an angle of 0° to 50° and have a width of 0.4 mm to 3.0 mm, wherein each incision has a main incision section and opens into each circumferential groove delimiting the tread rib with a respective incision edge section, wherein the main incision section and the incision edge section each have a depth in the radial direction, wherein the depth of the main incision section is less than the depth of the incision edge section and the depth of the incision edge section is 200% to 400% of the depth of the main incision section,wherein the incision edge section in the interior of the profile rib opens over its entire extent into a cavity extending from the circumferential groove and wider than the incision.

[0002] Such a pneumatic vehicle tire is known, for example, from US 2014 / 0166173 A1. The pneumatic vehicle tire has a tread with a circumferentially extending tread rib, which is bordered on each side by a circumferential groove. Located inside the tread rib is a circumferentially extending insert spaced from the outer surface of the rib. This insert is removed after the tread rib has been worn down, forming another groove. The tread rib is further provided with incisions running in the axial direction (as viewed from above) with a width of 0.6 mm.According to one variant, the sipe, viewed in plan view, is composed of a main sipe section and two sipe edge sections, with the main sipe section having a depth of approximately 50% of the tread depth and each sipe edge section having a depth of approximately 100% of the tread depth, so that the depth of each sipe edge section is 200% of the depth of the main sipe section. The sipe edge sections each open into a cavity with a circular cross-section, thus avoiding stress peaks in this area. The tire should offer good wet grip while maintaining high tread rigidity.

[0003] US 2011 / 0108176 A1 discloses a pneumatic vehicle tire with a tread with profile ribs provided with transverse cuts extending in the axial direction in plan view, with a width of 0.5 mm to 1.5 mm. According to one embodiment, each cut is composed of a shallow cut section and a deeper cut section terminating in a cavity, wherein the cavity is wider than the cut and has a circular cross-section. Alternatively, the cavity can be elliptical, for example, when viewed in cross-section. The cavity is advantageous for the crack resistance of the adjacent rubber material.

[0004] EP 3 415 343 A1 discloses a pneumatic vehicle tire with a tread with positive profile sections defined by circumferential and transverse grooves, which are provided with traversing incisions that, over their entire extent, each open into a channel-shaped cavity with funnel-shaped end sections. The end sections are intended to ensure low stresses at the ends of the incisions, which is beneficial with regard to the durability of the tread.

[0005] US 2012 / 0234443 A1 discloses a pneumatic vehicle tire with a tread with positive tread sections with traversing incisions, each of which leads into a channel. The channels have a diameter that increases toward their ends.

[0006] US 2019 / 0084352 A1 discloses another pneumatic vehicle tire with a tread having a profile rib provided with traversing incisions. The incisions each comprise a shallow main incision section and two deeper edge incisions, with the depth of the main incision section being 40% to 55% of the depth of the edge incisions.

[0007] US 2017 / 0253090 A1 discloses a pneumatic vehicle tire having a tread with a profile rib with traversing cuts which, viewed in plan view, are composed of a straight, shallow main section and an arcuate, deeper cut edge section.

[0008] Furthermore, WO 2015 / 128106 A1 discloses a pneumatic vehicle tire, which can be a tire for passenger cars, vans, or heavy-duty vehicles (commercial vehicles). According to one exemplary embodiment, the tire has a tread with profile ribs separated from one another by circumferential grooves and divided into profile blocks by transverse grooves, wherein axially extending cuts with a width of 0.4 mm to 0.6 mm are formed in the profile ribs. Viewed in plan view, the cuts are each composed of a main cut section extending over at least 50% of the cut length, in the exemplary embodiment over the majority of the extent of the cut, and two cut edge sections opening into the circumferential grooves. The main cut section has a depth of at least 70% of the profile depth, and the cut edge sections have a depth of 30% to 70% of the depth of the main cut section.A recess is formed on at least one cut wall, which is located radially within a depth of 50% of the profile depth, is surrounded on the edge by at least 2 mm of cut wall and increases the water absorption capacity of the cut.

[0009] It is well known that tread ribs are provided with cuts to improve grip. Furthermore, cuts contribute to the drainage of the tread pattern, with their water absorption capacity decreasing with increasing tread wear, thus diminishing wet grip properties. At the same time, the cuts undesirably reduce the stiffness of the tread ribs, thereby impairing the transfer of traction force to the surface.

[0010] The invention is based on the object of enabling a pneumatic vehicle tire of the type mentioned at the outset to have good wet grip properties over the entire tread wear while maintaining a profile stiffness which is more favorable with regard to the transmission of traction force.

[0011] The stated object is achieved according to the invention in that the main incision section has a length determined along the center line of the incision of 65% to 90% of the length of the incision determined in a consistent manner, wherein the depth of the main incision section is 10% to 30% of the profile depth and wherein the cavity, viewed in the cross section of the incision, is elongated in the radial direction and has a length of 25% to 45% of the profile depth in the radial direction.

[0012] On new or slightly worn treads, the sipes ensure good drainage of the tread ribs, particularly due to their ability to open significantly when the tire passes through the footprint. This allows the sipe edges to optimally function as gripping edges on wet surfaces. The shallower sipe main section ensures high tread rib rigidity throughout the tire's service life (tread wear), which is beneficial for traction force transmission, compared to tread patterns with sipes and deeper main sections.As tread wear progresses, the cavities extend to the tread periphery. Due to their wider design compared to the cuts, the tread ribs, which have become stiffer due to tread wear, continue to allow for good water absorption. The absorbed water is advantageously drained directly into the circumferential groove(s). This makes the edges on the tread periphery, created by the cavities, particularly effective as gripping edges, particularly pronounced. The elongated cavity has proven particularly advantageous in terms of water absorption and water drainage to the circumferential groove.

[0013] According to a preferred embodiment, the cavity, viewed in the cross-section of the cut, has a width of 200% to 500%, in particular 300% to 400%, preferably 330% to 370%, of the width of the cut at its widest point. This contributes to good water absorption when driving on wet roads, further improving the wet grip properties.

[0014] Furthermore, it is advantageous if the length of the cavity is 30% to 40%, preferably 33% to 37%, of the profile depth.

[0015] According to a further preferred embodiment, the cavity extends radially to a depth of 75% to 100%, in particular up to 95%, of the tread depth. This contributes to maintaining good wet grip properties throughout tread wear.

[0016] For the transmission of traction force, it is also advantageous if the depth of the main cut section is up to 25%, in particular up to 20%, of the tread depth.

[0017] A particularly advantageous compromise with regard to wet grip properties and the profile stiffness relevant for traction force transmission can be achieved by setting the depth of the sipe edge section to 250% to 350%, in particular 290% to 310%, of the depth of the main sipe section.

[0018] According to a further preferred embodiment, the incision edge section, viewed in cross-section through the incision, extends in the shape of a wave, in particular in the shape of a harmonic wave, particularly preferably in the shape of a harmonic zigzag wave or a harmonic sawtooth wave. This enables favorable support effects for the tread rib segments formed by the incision with regard to tread rigidity, especially in new or slightly worn tires.

[0019] A further preferred embodiment is characterized in that the cut is straight in plan view—relative to its center line—and the edge section of the cut is straight when viewed from above. This is particularly advantageous with regard to the openability of the cut and thus for water absorption, thus contributing to an improvement in wet grip properties.

[0020] According to a further preferred embodiment, the main incision section, viewed in plan view, extends at least over the majority of its extent, in particular over at least 70% of its length determined along the centerline of the incision, in the shape of a wave, in particular in the shape of a harmonic wave, particularly preferably in the shape of a harmonic zigzag wave or a harmonic sawtooth wave. This measure contributes in particular to a further increase in the transverse rigidity of the profile rib.

[0021] In this embodiment, it is furthermore advantageous if the wavelength of the wave of the main section of the incision is 25% to 40%, in particular up to 33%, of the length determined along the center line of the incision.

[0022] In addition, in this design it is advantageous if the amplitude of the wave of the main section of the cut is 75% to 200%, in particular 125% to 175%, of the width of the cut.

[0023] For the stiffness of the profile rib, it is also advantageous if the course of the wave present in the cross-section of the cut in the cut edge section is continued in the main cut section.

[0024] According to a further preferred embodiment, the length of the main cut section is up to 85% of the length of the cut. The shallower main cut section therefore extends over the majority of the cut in this embodiment, which is advantageous with regard to profile rigidity.

[0025] A further preferred embodiment is characterized in that the cavity has a plane of symmetry extending in the radial direction, which contains the center line of the incision aligned in the direction of extension of the incision in plan view.

[0026] A further preferred embodiment relates to a pneumatic vehicle tire with a tread having at least one profile rib, which is bordered on each side by a circumferential groove designed to the profile depth. The cuts are each formed from the main cut section and two cut edge sections, the cut edge sections each opening into a cavity extending from the respective circumferential groove and wider than the cut. The provision of such specially designed cuts in central profile ribs is particularly advantageous because the described effects occur to a greater extent with them.

[0027] Further features, advantages and details of the invention will now be explained in more detail with reference to the drawing, which schematically shows exemplary embodiments of the invention. Fig. 1 a simplified plan view of a profile block of a tread of a commercial vehicle tire with a first embodiment of the invention, Fig. 2 an enlarged oblique view of a visualization of a cut formed in the profile block, Fig. 3 a front view of the incision visualization Fig. 2 , Fig. 4 a simplified top view of the incision visualization Fig. 2 , Fig. 5 a section along the line VV Fig. 3 und Fig. 4 , Fig. 6 a section along the line VI-VI Fig. 3 und Fig. 4 , Fig. 7a bis Fig. 7c Sections through a section of an incision with further design variants and Fig. 7d a section through a partial area of ​​an incision with a further embodiment variant which does not fall within the scope of protection of claim 1.

[0028] Pneumatic vehicle tires designed according to the invention are tires for motor vehicles, in particular for multi-track motor vehicles, and preferably commercial vehicle tires of radial design, in particular for trucks or buses.

[0029] In Fig. 1 1 shows a tread block 1 of a commercial vehicle tire formed in the central tread area, which is elongated in the circumferential direction and is part of a tread rib running circumferentially and designed as a row of blocks. The tread block 1 is delimited laterally by circumferential grooves 2a, which in the illustrated embodiment are straight in plan view. In the circumferential directions, the tread block 1 is delimited by transverse grooves 2b, to which further tread blocks 1 belonging to the tread rib preferably adjoin. The circumferential grooves 2 are radially spaced in the respectively provided tread depth T 1 (indicated in Fig. 6 ), which for commercial vehicle tires is preferably 10.0 mm to 25.0 mm.

[0030] The profile block 1 is provided over its circumference with a plurality of incisions 3, which traverse the profile block 1 and - based on center lines m E aligned in the direction of extension of the incisions 3 - run parallel to one another in plan view and in the exemplary embodiment in the axial direction. The further design of the incisions 3 is described below with reference to the Fig. 2 bis Fig. 6 shown incision 3 is explained.

[0031] The incision 3 has a plane of symmetry E 1 bisecting the center line m E and spanned by the circumferential direction and the radial direction ( Fig. 3, Fig. 4 ). How Fig. 2 bis Fig. 4 particularly in combination with each other, the incision 3, viewed in plan view, is composed of two incision edge sections 3a and a main incision section 3b extending over most of its extent, wherein the incision edge sections 3a in the interior of the profile block 1 each open over their entire extent into a cavity 4 emanating from the corresponding circumferential groove 2 ( Fig. 1 in conjunction with Fig. 2 and Fig. 6 ).

[0032] The incision 3 has two corresponding incision walls 5 ( Fig. 2 , Fig. 4 bis Fig. 6 ), a constant width b E determined between the cutting walls 5 ( Fig. 4 bis Fig. 6 ) of 0.4 mm to 3.0 mm, in particular up to 2.0 mm, and a length l E determined along the center line m E ( Fig. 4 ) on.

[0033] The incision edge sections 3a run, viewed in plan view ( Fig. 4 ), straight and aligned with each other, have a length la ( Fig. 4 ) and in the radial direction a depth ta ( Fig. 3 , Fig. 6 ). The incision edge sections 3a also run, viewed in cross-section perpendicular to the center line m E ( Fig. 6 ), zigzag-shaped into the radial interior of the profile block 1 ( Fig. 2 , Fig. 6 ) and flow over their entire length la at a depth ta into the already mentioned cavities 4 ( Fig. 2, Fig. 3 ). The incision walls 5 therefore have a corresponding zigzag-shaped course in the radial direction in the incision edge sections 3a, viewed in cross-section perpendicular to the center line m E ( Fig. 6 ).

[0034] According to Fig. 4 the main incision section 3b has a length lb of 65% to 90%, in particular of up to 85%, of the length l E of the incision 3, determined on the tread periphery along the center line m E and in particular constant over its radial extent, and is, viewed in plan view, at least over the majority of its length lb , in particular over at least 70% of its length lb , in the form of a harmonic zigzag wave with a wavelength λ b and an amplitude A b, wherein in the embodiment shown it runs over 2.5 wavelengths λ b - ie over 1.25 wavelengths λ b on each side of the plane of symmetry E 1 . The wavelength λ b is 25% to 40%, in particular up to 33%, of the length lb , the amplitude A b is 75% to 200%, in particular 125% to 175%, of the width b E of the incision 3. Furthermore, the incision main section 3b has a constant depth tb ( Fig. 3 , Fig. 5 ) of 10% to 30%, in particular of up to 25%, preferably of up to 20%, of the profile depth T 1 ( Fig. 6 ), whereby in the embodiment the already mentioned zigzag-shaped course of the incision walls 5 formed in the radial direction in the incision edge sections 3a is continued in the incision main section 3b ( Fig. 2 , Fig. 5 ). In the embodiment shown, the depth tb of the main incision section 3b is selected such that the main incision section 3b, viewed in cross-section perpendicular to the center line m E, extends over a single prong and is therefore designed in a horizontal V-shape ( Fig. 5 ).

[0035] How Fig. 3, Fig. 4 and Fig. 6 in combination, the already mentioned cavities 4 each have a symmetry plane E 2 ( Fig. 3, Fig. 4 ), a symmetry plane E 3 running orthogonally (perpendicular) to the symmetry plane E 2 and parallel to the tread periphery ( Fig. 3 , Fig. 6 ) and a symmetry plane E 4 ( Fig. 4 , Fig. 6 ). The cavities 4 extend radially from the tread periphery to a depth t HR ( Fig. 3 , Fig. 6 ) of 75% to 100%, in particular of up to 95%, of the profile depth T 1 , are elongated in the radial direction, have in the symmetry plane E 2 in the radial direction a length l HR ( Fig. 3 ) of 25% to 45%, in particular of 30% to 40%, preferably of 33% to 37%, of the profile depth T 1 ( Fig. 6 ) and in the symmetry plane E 3 a width b HR determined perpendicular to the symmetry plane E 4 ( Fig. 6 ) from 200% to 500%, in particular from 300% to 400%, preferably from 330% to 370%, of the width b E ( Fig. 6 ) of incision 3. How Fig. 6 shows, the cavities 4, viewed in cross-section perpendicular to the center line m E, are designed in the form of rectangles, which have semicircles instead of the short sides. According to Fig. 3 the cavities 4 are further designed such that they do not protrude beyond the incision edge sections 3a, ie they do not protrude into the area radially inside the main incision section 3b. Preferably, the depth t HR , the length l HR and the depth ta are coordinated with one another such that the depth ta of the incision edge sections 3a ( Fig. 3 , Fig. 6 ) 200% to 400%, in particular 250% to 350%, particularly preferably 290% to 310%, of the depth tb of the main incision section 3b.

[0036] Fig. 7a bis Fig. 7d show cross sections through cavities 4 I< to 4 IV< , which are variants of the cavity 4. The already mentioned depth ta of the cut edge sections 3a is adapted to the design of the cavities 4 I< to 4 IV< in such a way that the cavities 4 I< to 4 IV< extend to the already mentioned depth t HR ( Fig. 3 ) from 75% to 100%, in particular up to 95%, of the tread depth T 1.

[0037] The cavity 4 I< ( Fig. 7a ) differs from cavity 4 in that, viewed in cross-section perpendicular to the center line m E, it is oval in shape.

[0038] The cavity 4 II< ( Fig. 7b ) differs from cavity 4 in that, viewed in cross-section perpendicular to the center line m E, it is designed in the shape of a rectangle with corners rounded, for example, along quarter circles.

[0039] The cavity 4 III< ( Fig. 7c ) is symmetrical exclusively with respect to the aforementioned planes of symmetry E 2 and E 4, is drop-shaped when viewed in cross-section perpendicular to the center line m E, and is composed of a radially outer spatial part 4 III< a and a radially inner spatial part 4 III< b, wherein the radially inner spatial part 4 III< b has a larger volume than the radially outer spatial part 4 III< a. The radially inner spatial part 4 III< b is, when viewed in cross-section perpendicular to the center line m E, essentially in the shape of an isosceles trapezoid elongated in the radial direction, wherein the base of the trapezoid (longer base side) borders on the radially outer spatial part 4 III< a. The radially outer spatial part 4 III< a is, when viewed in cross-section perpendicular to the center line m E, is isosceles-triangular in shape, wherein the triangular legs are concavely curved towards one another, i.e. curved inwards. Furthermore, all corner regions of the cavity 4 III< are rounded.

[0040] The cavity 4 IV< ( Fig. 7d ) has a circular cross-section with a diameter d HR of 200% to 500%, in particular of 300% to 400%, preferably of 330% to 370%, the width b E ( Fig. 4 bis Fig. 6 ) of incision 3.

[0041] The invention is not limited to the described embodiments.

[0042] The tire tread has at least one circumferentially encircling rib with traversing cuts. The rib may be structured in a block-like manner with traversing transverse grooves in tread blocks and / or with transverse grooves ending in a blind groove. The tread rib is bordered at least on one side by a circumferential groove that runs randomly in plan view, for example, in a zigzag shape, into which the cuts open via a cut edge section. Such tread ribs include, in particular, shoulder-side tread ribs in which traversing cuts extend at least to the corresponding lateral edge of the ground contact patch (statically determined footprint, determined with a tire mounted on a standard rim, loaded at 70% of the maximum load capacity, internal pressure 85% of the standard pressure, according to ETRTO standards).In plan view, the incisions can run at an angle of 0° to 50° relative to their center lines to the axial direction. Furthermore, the incisions can run in any desired direction in plan view, for example, straight or curved or wavy, either entirely or in sections. In the case of incisions that are curved at least in sections, the center lines follow the curved shape, whereby the angle at which such incisions run to the axial direction is determined relative to a line connecting the ends of the center line and extending straight in plan view. Bezugsziffernliste

[0043] 1Tread block 2aCircumferential groove 2bTransverse groove 3Cut 3aCut edge section 3bCut main section 4, 4 I< to 4 IV< Cavity 4‴aradial outer spatial part 4‴bradial inner spatial part 5Cut wall A b Amplitude b E , b HR Width d HR Diameter E 1 , E 2 , E 3 , E 4 Symmetry plane la , lb , l E , l HR Length m E Center line ta , tb , t HR Depth T 1 Profile depth λ b Wavelength

Claims

1. Pneumatic vehicle tyre, in particular utility-vehicle tyre, having a tread with at least one profile rib (1) which runs around in a circumferential direction, is delimited on at least one side by a circumferential channel (2a) formed to a profile depth (T1) and is traversed by sipes (3), said sipes, in plan view, at least in groups, extending parallel to one another and extending at an angle of 0° to 50° to the axial direction and having a width (bE) of 0.4 mm to 3.0 mm, wherein each sipe (3) has a sipe main portion (3b) and opens out by way of a respective sipe edge portion (3a) into each circumferential channel (2a) that delimits the profile rib (1), wherein the sipe main portion (3b) and the sipe edge portion (3a) have respective depths (ta, tb) in a radial direction, wherein the depth (tb) of the sipe main portion (3b) is less than the depth (ta) of the sipe edge portion (3a) and the depth (ta) of the sipe edge portion (3a) is 200% to 400% of the depth (tb) of the sipe main portion (3b), wherein, in the interior of the profile rib (1), the sipe edge portion (3a), over its entire extent, opens out into a cavity (4, 4I to 4III) which departs from the circumferential channel (2) and which is of wider form in comparison with the sipe (3), characterized in that the sipe main portion (3b) has a length (lb), determined along the midline (mE) of the sipe (3), of 65% to 90% of the length (lE), determined in a corresponding manner, of the sipe (3), wherein the depth (tb) of the sipe main portion (3b) is 10% to 30% of the profile depth (T1), and wherein the cavity (4, 4I to 4III), as seen in a cross section of the sipe (3), is elongate in the radial direction and has in the radial direction a length (lHR) of 25% to 45% of the profile depth (T1).

2. Pneumatic vehicle tyre according to Claim 1, characterized in that the cavity (4, 4I to 4III), as seen in a cross section of the sipe (3), has at its widest position a width (bHR) of 200% to 500%, in particular of 300% to 400%, preferably of 330% to 370%, of the width (bE) of the sipe (3).

3. Pneumatic vehicle tyre according to Claim 1 or 2, characterized in that the length (lHR) of the cavity (4, 4I bis 4III) is 30% to 40%, preferably 33% to 37%, of the profile depth (T1).

4. Pneumatic vehicle tyre according to one of Claims 1 to 3, characterized in that the cavity (4, 4I to 4III), in the radial direction, reaches a depth (tHR) of 75% to 100%, in particular of up to 95%, of the profile depth (T1).

5. Pneumatic vehicle tyre according to one of Claims 1 to 4, characterized in that the depth (tb) of the sipe main portion (3b) is up to 25%, in particular up to 20%, of the profile depth (T1).

6. Pneumatic vehicle tyre according to one of Claims 1 to 5, characterized in that the depth (ta) of the sipe edge portion (3a) is 250% to 350%, in particular 290% to 310%, of the depth (tb) of the sipe main portion (3b).

7. Pneumatic vehicle tyre according to one of Claims 1 to 6, characterized in that the sipe edge portion (3a), as seen in a cross section of the sipe (3), extends in the form of a wave, in particular in the form of a harmonic wave, particularly preferably in the form of a harmonic zigzag wave or a harmonic sawtooth wave.

8. Pneumatic vehicle tyre according to one of Claims 1 to 7, characterized in that, in plan view, the sipe (3) - based on its midline (mE) - is of straight form, and, as seen in plan view, the sipe edge portion (3a) extends straight.

9. Pneumatic vehicle tyre according to one of Claims 1 to 8, characterized in that, as seen in plan view, the sipe main portion (3b), at least over the majority of its extent, in particular over at least 70% of its length (lb), determined along the midline (mE) of the sipe (3), extends in the form of a wave, in particular in the form of a harmonic wave, particularly preferably in the form of a harmonic zigzag wave or a harmonic sawtooth wave.

10. Pneumatic vehicle tyre according to Claim 9, characterized in that the wavelength (λb) of the wave of the sipe main portion (3a) is 25% to 40%, in particular up to 33%, of the length (lb) determined along the midline (mE) of the sipe (3).

11. Pneumatic vehicle tyre according to Claim 9 or 10, characterized in that the amplitude (Ab) of the wave of the sipe main portion (3a) is 75% to 200%, in particular 125% to 175%, of the width (bE) of the sipe (3).

12. Pneumatic vehicle tyre according to one of Claims 7 to 11, characterized in that the profile of the wave that is present in the sipe edge portion (3a) in a cross section of the sipe (3) is continued in the sipe main portion (3b).

13. Pneumatic vehicle tyre according to one of Claims 1 to 12, characterized in that the length (lb) of the sipe main portion (3b) is up to 85% of the length (lE) of the sipe (3).

14. Pneumatic vehicle tyre according to one of Claims 1 to 13, characterized in that the cavity (4, 4I to 4III) has a radially extending plane of symmetry (E4) which contains the midline (mE) of the sipe (3), said midline being oriented in the direction of extent of the sipe (3) in plan view.

15. Pneumatic vehicle tyre having a tread with at least one profile rib (1), which is delimited on each side by a respective circumferential channel (2a) formed to a profile depth (T1), according to one of Claims 1 to 14, characterized in that the sipes (3) are each formed of the sipe main portion (3b) and two sipe edge portions (3a), wherein the sipe edge portions (3a) each open out into a cavity (4, 4I to 4IV) which departs from the respective circumferential channel (2) and which is of wider form in comparison with the sipe (3).