Vehicle tires

Abstract

Vehicle tires with a profiled tread (1) with profile positives (4, 5, 6) and with grooves (2) designed in the intended profile depth (T) and with at least one circumferential circumferential groove (7, 10) with a radially symmetrical and trough-shaped cross-section and two groove flanks (7a, 10a) which each transition tangentially into an outer surface of a profile positive (4, 5, 6) with a radially outer, outwardly arc-shaped section (7a2, 10a2) and which each transition into or form a groove bottom (7b, 10b) with a radially inner, inwardly arc-shaped section (7a1, 10a1). The circumferential groove (7, 10) has a depth (t2) of 40% to 60% of the profile depth (T) at its deepest point and a width (b3) on the outer surfaces of the profile positives (4, 5, 6) that is 3.5 to 5 times its depth (t2).

Description

[0001] The invention relates to a vehicle tire with a profiled tread with profile positives and with grooves executed in the intended profile depth, as well as with at least one circumferentially circumferential groove, radially symmetrical and trough-shaped in cross-section, with two groove flanks, each of which transitions tangentially into an outer surface of a profile positive with a radially outer, outwardly arc-shaped section and each of which transitions into or forms a groove bottom with a radially inner, inwardly arc-shaped section.

[0002] Such a vehicle tire is known, for example, from DE 11 215 004 635 T5. The tread of this tire has a number of circumferential main grooves that divide the tread into profile ribs. The main grooves are symmetrical in radial cross-section and are generally trough- or rounded V-shaped. The vehicle tire known from US 5450885 A also has a tread with circumferential grooves. The opposing groove flanks of the circumferential grooves are bent outwards, widening the circumferential grooves, such that the angle of inclination of the groove flanks relative to the radial direction increases continuously outwards. This design is intended to reduce the air-pumping noise in the circumferential grooves.DE 69402815 T2 discloses a vehicle tire with a tread having at least one circumferential groove as the main groove, which in one embodiment has a groove base with a flat cross-section that runs parallel to the tread surface. The groove flanks consist of a convexly curved radially outer main section and a concavely curved radially inner section. With a tread featuring such circumferential grooves, the air resonance in the main grooves, and thus the road noise, is effectively reduced without impairing the drainage effect of the main grooves.

[0003] Circumferential grooves are therefore known whose groove flanks are inclined in the radial direction, transition tangentially into the outer surfaces of the profile positives, and have a round or rounded groove base. In circumferential grooves designed in this way, the susceptibility of the rubber material to cracking at the groove flanks and the groove base is reduced, primarily because the occurrence of critical pressure peaks is diminished.

[0004] The invention is based on the objective of designing circumferential grooves in the tread of a vehicle tire of the type mentioned above in such a way that a particularly uniform pressure distribution is achieved over the course of the groove flanks and the groove base, thereby avoiding the occurrence of pressure peaks better than before.

[0005] The problem set out in the invention is solved by the circumferential groove having a depth of 40% to 60% of the profile depth at its deepest point and a width on the outer surfaces of the profile positives that is 3.5 to 5 times its depth.

[0006] Circumferential grooves designed according to the invention are therefore very wide at the tread periphery relative to their depth. The trough-shaped cross-section ensures gently rounded transitions from the groove flanks to the tread periphery and a rounded groove base. This results in a very even distribution of the pressure acting on the groove flanks and the groove base of the circumferential grooves during tire rolling, effectively preventing the occurrence of pressure peaks.

[0007] It is particularly advantageous for even pressure distribution and to avoid the occurrence of pressure peaks if the width of the circumferential groove on the outer surfaces of the profile positives is 4 to 4.5 times its depth.

[0008] Several other preferred measures are particularly advantageous for a uniform distribution of the pressure that occurs.

[0009] In one of these measures, the groove flanks each consist of the two arc-shaped sections and, viewed in the radial cross-section of the circumferential groove, curve in a flat S-shape overall, forming a turning point.

[0010] In a further development of these measures, the inflection point between the arc-shaped sections is located at a depth of 40% to 60% of the circumferential groove depth. It is particularly advantageous if the inflection tangent at the inflection point of the groove flank sections runs at an angle of 50° to 70° relative to the radial direction, so that the circumferential groove opens wide towards the outer surfaces of the profile positives.

[0011] For passenger car tires, it is particularly advantageous for a uniform pressure distribution on the groove flanks if the radially inner, inwardly curved section of the groove flanks runs along a circular arc with a radius of 3.00 mm to 5.00 mm and if, furthermore, the radially outer, outwardly curved section runs along a circular arc with a radius of 5.00 mm to 7.00 mm, wherein this radius is at least 1.00 mm, in particular at least 2.00 mm, larger than the radius of the circular arc of the radially inner, inwardly curved section of the groove flanks.

[0012] Another measure that is advantageous with regard to a favorable pressure distribution consists in the fact that the radially inner, inwardly curved sections of the two groove flanks either jointly form the rounded groove bottom or transition tangentially into a groove bottom that is straight in cross-section and has an axial width of 2.00 mm to 5.00 mm.

[0013] Due to its relatively wide profile compared to its shallow depth, the circumferential groove also provides good drainage on wet subsoil. To further enhance drainage, a series of holes, particularly circular ones, can be formed at the bottom of the circumferential groove. The largest of these holes has a diameter of 3.00 mm to 5.00 mm. Advantageously, the holes extend from the bottom of the circumferential groove to a depth that is at least 70% and at most equal to the profile depth.

[0014] Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which shows an embodiment of the invention. Fig. 1 a top view of a circumferential section of a profiled tread of a vehicle tire, Fig. 2 an enlarged view of a detail of the Fig. 1, Fig. 3 an enlarged section along line III-III of the Fig. 2, Fig. 4 an enlarged section along line IV-IV of the Fig. 2, Fig. 5 an enlarged section along line VV of the Fig. 2, Fig. 6 an enlarged section along line VI-VI of the Fig. 2 and Fig. 7 an enlarged section along line VII-VII of the Fig. 2.

[0015] Vehicle tires designed according to the invention are in particular pneumatic tires for motor vehicles, especially for multi-track motor vehicles such as trucks and passenger cars, vans or SUVs, and preferably radial tires for rims with an integer rim diameter of 13 inches to 24 inches, in particular from 18 inches to 23 inches.

[0016] Fig. Figure 1 shows a top view of a circumferential section of a directional, profiled tread 1 for a vehicle tire, particularly for passenger cars. Line AA indicates the circumferential centerline of the tread 1, the lateral edges of the tread's contact patch are indicated by lines L, and B marks the maximum width of the contact patch. The contact patch corresponds to the statically determined footprint according to ETRTO standards (load at 70% of the maximum bearing capacity at an internal pressure of 85% according to the ETRTO standard).

[0017] The profiled tread strip 1 in the example is symmetrical with respect to the center line AA and has a flat circumferential groove 7 running along the center line AA in the circumferential direction, as well as V-shaped oblique grooves 2 running across the width of the tread strip as main grooves, which, starting at or near the center line AA, each consist of a straight main section 2a and a shoulder-side section 2b that connects to it via a rounded bend. The main sections 2a run parallel to each other at an angle α ( Fig. 2) of 10° to 20°, in particular 12° to 17°, relative to the circumferential direction (midline AA), the shoulder-side sections 2b at an angle β ( Fig. 2) at 50 to 70° to the circumferential direction and preferably also straight. In each half of the tread, the main sections 2a extend over 25% to 35% of the width B of the tread 1 in the ground contact area. The vehicle tire is to be mounted on the vehicle such that the inner ends of the diagonal grooves 2 are in contact with the ground when the tire rolls forward (see arrow R). a in Fig. 1 and Fig. 2) first come into contact with the substrate.

[0018] The main sections 2a of the diagonal grooves 2, which run almost circumferentially in the central tread area, have a distance a1 between them, determined perpendicular to and between the center lines of the main sections 2a, which is between 10.00 mm and 15.00 mm. Due to the larger angle β in the circumferential direction, the shoulder-side sections 2b of the diagonal grooves 2 have a significantly larger distance between them. Therefore, an additional groove 3 is formed approximately midway between the successive shoulder-side sections 2b in the circumferential direction. Each additional groove 3 has a section 3a on the outer side of the tread, which runs parallel to the shoulder-side sections 2b, and a section 3b that connects to this via a rounded bend and runs towards the center of the tread and parallel to a main section 2a.

[0019] The main sections 2a each have a depth T that is constant along their course and consistent for all main sections 2a (in Fig. 4 to 7 shown), each corresponding to the tread depth intended for the new tire and measuring 6.00 mm to 8.00 mm, in particular up to 7.00 mm. The shoulder sections 2b, immediately adjoining the main sections 2a, also have a depth T, their depth decreasing towards the tire shoulders or the tread edges L. In the embodiment shown, the main sections 2a, the shoulder sections 2b, and the additional grooves 3 at the tread periphery, measured between their edges there, also have a width b1 (in Fig. 2 (shown in main section 2a) from 2.50 mm to 4.00 mm.

[0020] Between the circumferentially successive oblique grooves 2, block-like profile positives 4, 5, and 6 are formed and bounded by the oblique grooves 2. On the shoulder side, between circumferentially successive shoulder-side sections 2b, are the profile positives 4, which have projections 4a extending a short distance between two circumferentially successive main sections 2a. The projections 4a have a maximum extension length I1, determined between the parallel subsections of the main sections 2a, of 30.00 mm to 50.00 mm. Each profile positive 5 follows the projection 4a towards the center of the tread and is an elongated block with a maximum extension length I2, also of 30.00 mm to 50.00 mm. The extension lengths I1 and I2 were determined on the outer surfaces of the profile positives 4 and 5 that are in contact with the substrate.Each profile positive 5 is connected between the adjacent main sections 2a by profile positive 6, which also extends elongated to the shallow circumferential groove 7 running along the center line AA. The mutually facing end regions of profile positives 4, 5 and 6 are rounded outwards in general and in plan view, in particular along a circular arc, at most a semicircle, with profile positives 4, 5 and 6 being connected to each other at these end regions by a bridge element 8.

[0021] Viewed from above, each bridge element 8 has an extent e determined at right angles to the center lines of the two main sections 2a ( Fig. 2) on, which is 20% to 40% of the distance a1, and parallel to the center lines of the two main sections 2a determines a width b2 ( Fig. 3) from 1.00 mm to 2.00 mm. On both sides of the bridge elements 8, funnel-shaped local widenings 9 of the main sections 2a of the inclined grooves 2 are therefore present as a result of the rounding of the end regions of the profile positives 4, 5 and 6 in plan view. As shown in the sectional view in Fig. As shown in Figure 3, the upper outer surface of the bridge element 8, which has a width b2, is located at a depth t2 of 40% to 60%, in particular about 50%, of the profile depth T. Along the rounded end region located further outwards from the tread, a flank of the respective profile positive slopes down towards the outer surface of the bridge element 8 at an angle γ1 of 0° to 7° relative to the radial direction, as shown in Figure 3. Fig. Figure 3 shows a flank 5a of a profile positive 5. The flank located along the rounded end region of the opposite profile positive slopes downwards at an angle γ2 of 20° to 35° to the radial direction, as shown. Fig. Figure 3 shows the sidewall 6a of a profile positive 6. The different inclination of these sidewalls 5a, 6a relative to the radial direction supports a low-turbulence flow of water through the diagonal grooves 2 when the tire rolls forward on wet surfaces.

[0022] In addition to the circumferential groove 7 running along the center line AA, two further flat circumferential grooves 10 are formed parallel to it, which superficially cross the main sections 2a of the oblique grooves 2 on the inside and near the rounded kinks.

[0023] How the sectional views in Fig. 4 and Fig. As shown in Figure 6, the circumferential grooves 7, 10 have a symmetrical, trough-shaped cross-section with two lateral groove flanks 7a, 10a. Viewed in the radial cross-section of the circumferential grooves 7, 10, the groove flanks 7a, 10a are generally shallowly S-shaped, specifically along two arc-shaped sections: a radially inner, inwardly curved section 7a1, 10a1 and a radially outer, outwardly curved section 7a2, 10a2. The inflection point between sections 7a1, 7a2 and 10a1, 10a2 is located at a depth t5 of 40% to 60% of the depth t2 of the circumferential grooves 7, 10, where the depth t2 is 40% to 60% of the profile depth T. The circumferential grooves 7, 10 have a width b3 on the outer surfaces of the profile positives 4, 5, 6, which is 3.5 to 5 times, in particular 4 to 4.5 times, the depth t2. The inflection tangent w tAt the inflection point of sections 7a1, 7a2 and 10a1, 10a2, the curve runs at an angle δ of 50° to 70° relative to the radial direction. The radially inner, inwardly curved section 7a1, 10a1 runs along a circular arc with a radius r1 of 3.00 mm to 5.00 mm, while the radially outer, outwardly curved section 7a2, 10a2 runs along a circular arc with a radius r2 of 5.00 mm to 7.00 mm, where the radius r2 is at least 1.00 mm, and in particular at least 2.00 mm, larger than the radius r1. The radially outer, outwardly curved section 7a2, 10a2 transitions tangentially into one of the outer surfaces of the profile positives 4, 5, and 6.In one embodiment, the radially inner, inwardly curved sections 7a1, 10a1 of the two groove flanks 7a, 10a together form an overall rounded groove bottom 7b, 10b; alternatively, the radially inner, inwardly curved sections 7a1, 10a1 transition tangentially into a narrow groove bottom, which is particularly straight in cross-section and has an axial width of 2.00 mm to 5.00 mm.

[0024] A series of holes 11 are formed around the entire circumference of the circumferential groove 7 at the base 7b of the groove 7. In the illustrated embodiment, the holes 11 have a circular cross-section in plan view with a diameter d1 of 3.00 mm to 5.00 mm; preferably, all holes 11 have the same diameter d1. As shown in the sectional view in Fig. As shown in Figure 5, the holes 11 extend from the base 7b to a depth t3, which is preferably at least 70% of the profile depth T and at most T', and have a U-shaped radial cross-section. The clear distance a2 between the circumferentially successive holes 11 is 4.00 mm to 10.00 mm and is preferably constant for all holes 11 within the circumferential groove 7.

[0025] On the bottom 10b of the circumferential grooves 10, holes 12 are formed in those sections of the circumferential grooves 10 that extend outside of intersection areas with main sections 2a of the oblique grooves 2. In these sections of the circumferential grooves 10, there is a row of holes 12, for example, six to ten holes 12, which are circular in plan view. As shown in the sectional view in Fig.As shown in Figure 7, the holes 12 have a radial cross-section in the shape of a U. The holes 12 have a maximum diameter d2 of 3.00 mm to 5.00 mm. Furthermore, the holes 12 extend to a depth t4 of 70% to 100% of the profile depth T. Within the rows of holes, the clear area a3 of the holes 13 is 4.00 mm to 8.00 mm, with the spacing a3 preferably being equal.

[0026] In other embodiments not shown, the holes 11, 12 are elongated in the direction of the circumferential grooves 7, 10, for example oval or elliptical. The aforementioned diameters d1 and d2 then refer to the greatest extent of the holes. Furthermore, the holes in the circumferential central groove can be arranged in groups of at least two. List of reference symbols 1 tread 2 diagonal grooves 2a Main Section 2b shoulder section 3 additional grooves Sections 3a and 3b 4, 5, 6 Profile positive 4a Approach 5a flank 6a Flank 7 circumferential groove 7a Groove flank Sections 7a1 and 7a2 7b Grooved floor 8 bridge elements 9 Widening 10 circumferential groove 10a Groove flank Sections 10a1 and 10a2 10b grooved floor 11 holes (circumferential groove 7) d1 diameter (hole 11) 12 holes d2 diameter (hole 12) a1, a2, a3 distance B Wide ground contact area b1 Width (Main section 2a) b2 width (bridge element 8) b3 Width (circumferential groove 7, 10) e Extension (bridge element 8) L tread edge I1 Extension length (Approach 4a) I2 Extension length (Profile positive 5) t1 depth (bridge element 8) t2 depth (circumferential groove 7, 10) t3 depth (hole 11) t4 depth (hole 12) t5 Depth (turning point) w t turning tangent r1, r2 radius α Angle (Main Section 2a) β angle (shoulder-side section 2b) γ1 angle γ2 angle δ angle R a Rolling direction QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 11 215 004 635 T5

[0002] US 5450885 A

[0002] DE 69402815 T

[0002]

Claims

[1] Vehicle tyre with a profiled tread (1) with profile positives (4, 5, 6) and with grooves (2) designed in the intended profile depth (T) and with at least one circumferentially encircling, radially cross-sectionally symmetrical and trough-shaped circumferential groove (7, 10) with two groove flanks (7a, 10a), each of which merges tangentially into an outer surface of a profile positive (4, 5, 6) with a radially outer, outwardly circularly arcuate section (7a2, 10a2) and each of which merges into a groove base (7b, 10b) or helps to form the latter with a radially inner, inwardly circularly arcuate section (7a1, 10a1), characterized by that the circumferential groove (7, 10) has at its deepest point a depth (t2) of 40% to 60% of the profile depth (T) and at the outer surfaces of the profile positives (4, 5, 6) a width (b3) which is 3.5 times to 5 times its depth (t2). [2] Vehicle tyre according to claim 1, characterized bythat the width (b3) of the circumferential groove (7, 10) on the outer surfaces of the profile positives (4, 5, 6) is 4 times to 4.5 times its depth (t2). [3] Vehicle tyre according to claim 1 or 2, characterized by that the groove flanks (7a, 10a) are each composed of the two circular arc-shaped sections (7a1, 7a2, 10a1, 10a2) and, viewed in the radial cross-section of the circumferential groove (7, 10), extend in an overall flat S-shaped curve, forming a turning point. [4] Vehicle tyre according to claim 3, characterized by that the turning point between the sections (7a1, 7a2 and 10a1, 10a2) is located at a depth (t5) of 40% to 60% of the depth (t2) of the circumferential groove (7, 10). [5] Vehicle tyre according to claim 3 or 4, characterized by that the inflection tangent (w t ) at the turning point of the sections (7a1, 7a2, 10a1, 10a2) runs at an angle δ of 50° to 70° relative to the radial direction. [6] Vehicle tyre according to one of claims 1 to 5, characterized by that the radially inner, inwardly bent section (7a1, 10a1) runs along a circular arc with a radius (r1) of 3.00 mm to 5.00 mm. [7] Vehicle tyre according to one of claims 1 to 6, characterized by that the radially outer, outwardly bent section (7a2, 10a2) runs along a circular arc with a radius (r2) of 5.00 mm to 7.00 mm, this radius being at least 1.00 mm, in particular at least 2.00 mm, greater than the radius (r1) of the circular arc of the radially inner, inwardly bent section (7a1, 10a1). [8] Vehicle tyre according to one of claims 1 to 7, characterized bythat the radially inner, inwardly bent sections (7a1, 10a1) of the two groove flanks (7a, 10a) either together form the rounded groove base (7b, 10b) or merge tangentially into a groove base which is straight, in particular in cross-section, and has a width of 2.00 mm to 5.00 mm in the axial direction. [9] Vehicle tyre according to one of claims 1 to 8, characterized by that a row of holes (11, 12) which are in particular circular in plan view and which have a diameter (d1, d2) of 3.00 mm to 5.00 mm at their point of largest diameter is formed on the bottom (7b, 10b) of the circumferential groove (7, 10). [10] Vehicle tyre according to claim 9, characterized by that the holes (11, 12) extend from the bottom (7b, 10b) of the circumferential groove (7, 10) to a depth (t3, t4) which corresponds to at least 70% of the profile depth (T) and at most to the profile depth (T).

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