The invention concerns a tread profile of a vehicle tyre—in particular a utility vehicle tyre—having profile elements which are separated from one another by channels and are delimited radially outwardly by a radially outer surface, and with additional shallow grooves which are formed in the radially outer surface of profile elements and are delimited inwardly in the radial direction by a groove base, and are formed with decreasing depth along the extent of the groove, starting from a position of the greatest depth of the groove to the extent end of the groove pointing away from the deepest point.
Vehicle tyres of this type are known. In order to improve grip in off-road usage, it is known to form additional shallow grooves in the radially outer surface of profile elements, which are delimited by channels, of pneumatic tyres of utility vehicles. In off-road use in particular, material from the ground can then penetrate into the groove. Groove flanks allow additional grip of the tyre and hence improve traction or braking effect in off-road usage. The shallow form of the grooves allows safe implementation of the high desired stiffness of the profile element during use of the utility vehicle without additional measures. The usual designs of such pneumatic tyres of utility vehicles, with shallow grooves in raised profile elements, are however configured with relatively sharp-edged transitions between the grooves flanks and the groove base, which may promote the formation of cracks in the groove base. In particular in off-road usage of utility vehicle tyres, this may contribute to an undesirably heavy wear and undesirable premature failure of the tyre, and hence reduce the durability.
JP 2012035664 A discloses a car tyre with such shallow grooves in the radially outer surface of profile block elements that are delimited by channels, wherein the groove base rises constantly, starting from the deepest point of the groove along its extent up to the extent end pointing away from the position of the deepest point. The extent end of the groove base here ends at a pronounced radial distance from the radially outer surface of the profile block element. Thus the extent end forms a stepped transition to the radially outer surface. Because of the rising profile of the groove base, this design indeed allows an improved stress distribution and high stiffness of the profile block element despite the provision of grip edges. However, with this design, the transition formed between the groove base and the radially outer surface in the extension direction of the circumferential channel is not constant and has sharp edges at the groove base, which may promote the formation of cracks in the groove base. Such a design would still be associated with restricted durability in the channel base in off-road usage of utility vehicle tyres.
The invention is based on the object of allowing the design of such vehicle tyres utilizing the advantages of shallow grooves, in particular for off-road usage of utility vehicle tyres, while reducing the potential for crack formation.
According to the invention, the object is achieved by the design of a tread profile of a vehicle tyre—in particular a utility vehicle tyre—having profile elements which are separated from one another by channels and are delimited radially outwardly by a radially outer surface, and with additional shallow grooves which are formed in the radially outer surface of profile elements and are delimited inwardly in the radial direction by a groove base, and are formed with decreasing depth along the extent of the groove, starting from a position of the greatest depth of the groove to the extent end of the groove pointing away from the deepest point, according to the features of claim 1; wherein the groove base is formed with a constantly rising depth profile along the extent of the groove, starting from a position of the greatest depth of the groove to the extent end of the groove pointing away from the deepest point and formed in the radially outer surface, and wherein, at least in a first extent portion which extends as far as the extent end in the radially outer surface, the depth profile of the groove base is formed such that it rises in a degressive curve and with a tangential transition to the radially outer surface.
This design allows the vehicle tyre to still be produced with profile elements delimited by channels, utilizing the advantageous design of a shallow groove in the radially outer surface of the profile element in order to achieve good grip properties with high stiffness. The depth profile of the groove along its extent, starting from the deepest point up to the extent end of the groove pointing away from the deepest point, with its constantly rising design and degressively rising depth profile up to the extent end, with tangential transition to the radially outer surface, allows a particularly favourable stress distribution in the extension direction of the groove without sharp-edged transitions to the surface. The depth profile, which rises with a degressive curve with tangential transition, allows optimal transfer of forces to the groove base with minimum stress. Thus in off-road usage, the risk of crack formation in the groove base may be further reduced and the durability improved.
The implementation and use of utility vehicle tyres, as desired for vehicles in the building site, construction, mining or quarrying sectors or in other off-road uses, may thus be further improved.
The design of a vehicle tyre according to the features of claim 2 is particularly advantageous, wherein in a second extent portion—in particular starting from a position of greatest depth of the groove and extending up to the first extent end —, the groove base is formed with a depth profile which rises substantially linearly along the extent of the groove, starting from a position of the greatest depth of the groove to the extent end of the groove pointing away from the deepest point. This may even out the abrasion of the groove, and the effect of the grip edges can be maintained for a long time.
The design of a vehicle tyre according to the features of claim 3 is particularly advantageous, wherein the depth profile of the groove is formed with a depth profile which rises in a curve along its entire extent, starting from a position of the greatest depth to the extent end of the groove pointing away from the deepest point and formed in the radially outer surface. This may further improve the stress distribution in the groove base.
The design of a vehicle tyre according to the features of claim 4 is particularly advantageous, wherein the depth profile of the groove is formed with a depth profile which rises in a degressive curve along its entire extent, starting from a position of the greatest depth to the extent end of the groove pointing away from the deepest point and formed in the radially outer surface. In this way, it is possible both to even out abrasion of the groove and maintain the effect of the grip edges for a long time, and also further improve the stress distribution in the groove base.
The design of a vehicle tyre according to the features of claim 5 is particularly advantageous, wherein the depth profile of the groove is formed so as to rise in a curve with a turning point of the direction of curvature, along its extent, starting from the position of the greatest depth to the extent end of the groove pointing away from the deepest point and formed in the radially outer surface, wherein in particular, the groove base, in a second extent portion extending up to the first extent end, is formed with a depth profile which rises in a progressive curve along the extent of the groove, starting from a position of the greatest depth of the groove, and the turning point of the curvature direction of the depth profile is formed in the transition between the second and first extent portions. In this way, the stress in the groove base may be minimized and effective grip edges can be maintained for a long time despite abrasion.
The design of a vehicle tyre according to the features of claim 6 is particularly advantageous, wherein along its extent, the groove is delimited on both sides of the groove base by a respective groove flank, which each extend from the radially outer surface inwardly in the radial direction R, so as to enclose a tilt angle, measured in the section planes perpendicular to the extension direction of the groove, to the radial direction R, as far as the groove base, wherein along the extent of the groove, in the section planes perpendicular to the extension direction of the groove, the one flank is formed with a tilt angle α of which the minimum αmin formed in the groove is 20°≤αmin≤60°, and the other flank is formed with a tilt angle β, of which the minimum βmin formed in the groove is 20°≤βmin≤60°.
The design of a vehicle tyre according to the features of claim 7 is particularly advantageous, wherein along the extent of the groove, starting from the position of the deepest point in which α is αmin and β is βmin, up to the extent end of the groove pointing away from the deepest point and formed in the radially outer surface, at least one—in particular both—flank(s) are formed with a flank angle which increases, in particular continuously, wherein the flank angle(s) has/have their maximum value of 90° in the extent end. This allows a completely edge-free transition into the radially outer surface at the extent end of the groove.
The design of a vehicle tyre according to the features of claim 8 is particularly advantageous, wherein along the extent of the groove, starting from the deepest point of the groove up to the extent end of the groove pointing away from the deepest point and formed in the radially outer surface, the two flanks intersect at their radially inner extent end and thus form a linear groove base in the section line.
The design of a vehicle tyre according to the features of claim 9 is particularly advantageous, wherein along the extent of the groove, starting from the deepest point of the groove up to the extent end of the groove pointing away from the deepest point and formed in the radially outer surface, the two flanks intersect, in the section planes formed perpendicularly to the extension direction, at a distance from each other which forms the width of the groove base, wherein the distance and hence the width of the groove base is formed decreasing along the extent of the groove, starting from the deepest point of the groove in the direction of the extent end of the groove pointing away from the deepest point and formed in the radially outer surface.
The design of a vehicle tyre according to the features of claim 10 is particularly advantageous, wherein several—in particular two—such grooves formed in the profile element open into each other at the position of their deepest point so as to enclose an angle δ of their extension direction.
The design of a vehicle tyre according to the features of claim 11 is particularly advantageous, wherein two such grooves formed in the profile element open into each other at the position of their deepest point so as to enclose an angle δ of their extension direction, with 45° 5135°. In this way, circumferential and transverse forces may be absorbed.
The design of a vehicle tyre according to the features of claim 12 is particularly advantageous, wherein the position of the deepest point of the groove is positioned in a channel wall delimiting the profile element. In this way, water may be discharged optimally from the groove into the channel.
The design of a vehicle tyre according to the features of claim 13 is particularly advantageous, wherein the position of the deepest point of the groove is positioned at a distance from the channels delimiting the profile element. This may optimally counter an uneven abrasion.
The design of a vehicle tyre according to the features of claim 14 is particularly advantageous, wherein the tread profile is configured as an off-road profile.
The invention will be discussed in more detail below on the basis of the exemplary embodiments illustrated in
The circumferential ribs 1 and 6 are each formed in a shoulder of the pneumatic vehicle tyre and form the shoulder ribs. The circumferential ribs 2, 3, 4 and 5 are formed between the two shoulder ribs 1 and 6 in the axial direction A. The circumferential rib 1 and the circumferential rib 2 are separated from one another in the axial direction A by a circumferential channel 7, which extends in the circumferential direction U and is oriented in the circumferential direction U. The circumferential rib 2 and the circumferential rib 3 are separated from one another in the axial direction A by a circumferential channel 8 of known type, which extends over the entire circumference and is oriented in the circumferential direction U. The circumferential rib 3 and the circumferential rib 4 are separated from one another in the axial direction A by a circumferential channel 9, which extends over the entire circumference of the pneumatic vehicle tyre and is oriented in the circumferential direction U. The circumferential rib 4 and the circumferential rib 5 are separated from one another in the axial direction A of the pneumatic vehicle tyre by a circumferential channel 10 which extends over the entire circumference of the pneumatic vehicle tyre and is oriented in the circumferential direction U. The circumferential rib 5 and the circumferential rib 6 are separated from one another in the axial direction A of the pneumatic vehicle tyre by a circumferential channel 11, which extends over the entire circumference of the pneumatic vehicle tyre and is oriented in the circumferential direction U.
The circumferential ribs 1, 2, 3, 4, 5 and 6 are delimited toward the outside in the radial direction R of the pneumatic vehicle tyre by a radially outer surface 12 which forms the ground contact surface.
The circumferential channels 7, 8, 9, 10 and 11 are delimited inwardly in the radial direction R in the known fashion by a channel base which extends over the circumference of the pneumatic vehicle tyre. The circumferential channels 7, 8, 9, 10 and 11 are formed with a depth PT, measured in the radial direction R of the pneumatic vehicle tyre, which corresponds to the profile depth of the tyre.
As shown in
As evident from
As shown in
The extent length a is configured such that 5 mm≤a≤50 mm.
In the exemplary embodiment in
For normal requirements, the extent length a is selected such that
10 mm≤a≤35 mm.
For example, a=18 mm, c=9 mm and d=9 mm.
The extent length a is configured such that 10 mm≤a≤35 mm. In the exemplary embodiment in
As depicted in
The minimum value αmin or βmin in the position of the deepest point of the groove 13 is here formed with 20°≤αmin≤60° or 20°≤βmin≤60°. For example, αmin=40° and βmin=40°.
Thus in a symmetrical design, α=β.
In another, asymmetrical design, αmin>βmin.
The maximum depth Tmax is (0.05 PT)≤Tmax≤(0.25 PT). In the typical configuration of conventional off-road utility vehicle tyres, (0.1 PT)≤Tmax≤(0.2 PT).
The profile depth PT of such pneumatic utility vehicle tyres is usually
20 mm≤PT≤25 mm.
In an exemplary embodiment, starting from the position of the deepest point Tmax up to its extent end, the groove base 14 is formed with constant width B along the extent of the groove base.
In an alternative embodiment, starting from the position of the deepest point of the groove 13 in which the groove base has its maximum width B, the groove base 14 is formed with continuously decreasing width B along the extent of the groove base up to its extent end.
Such an embodiment of a groove 13 is depicted in
Similarly, in
In the embodiments described above, the position of the deepest point of the groove 13 with depth Tmax is in each case formed in a channel wall of a circumferential channel 7 or 9 delimiting the profile rib, so that the groove 13 or 13IV or 13′ or 13V opens with its deepest point into the adjacent circumferential channel 7 or 9.
In
In the circumferential rib 5, an exemplary embodiment is shown in which a groove 13 and groove 13″ are arranged such that they have a common deepest point. The one groove 13 extends in the axial direction A, starting from this position of the deepest point, in the direction of the circumferential channel 11. The other groove 13″ extends in a different extension direction, starting from this position of the deepest point, enclosing an angle δ to the extension direction of the groove 13 in the radially outer surface 12. The angle δ is configured such that 45°≤δ≤135°. The angle δ is configured for example such that δ=95°.
As shown in
In
The exemplary embodiment of the circumferential rib 6 in
In
Number | Date | Country | Kind |
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10 2017 222 342.1 | Dec 2017 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/076941 | 10/4/2018 | WO | 00 |