CA3000024C - A pneumatic vehicle tyre with a tread profile for winter conditions - Google Patents

Abstract

A pneumatic vehicle tire with a tread profile for increasing the power transmission from the tire to snow-covered or ice-covered roadways. The tread profile comprises rows of profile block or profile strips that are separated from one another by grooves and profile positives with spikes positioned in spike holes. In the profile, starting from the spike, shallow elongated recesses extending in the two circumferential directions are formed as reservoirs for receiving shards of ice produced when the spike scrapes on ice. The recesses extending in the two circumferential directions are configured to correspond. In addition, in the profile, starting from the spike, at least one further recess extends in the axial direction. The recesses extending in the two circumferential directions and the at least one recess extending in the axial direction are the only recesses per spike.
The recesses act as ice reservoirs for winter conditions.

Description

A PNEUMATIC VEHICLE TYRE WITH A TREAD PROFILE FOR WINTER
CONDITIONS
Field The invention relates to a pneumatic vehicle tire having a tread which has profile positives, for example profile block rows or profile strips, which are separated from one another by channels, for example circumferential channels, transverse channels, oblique channels and the like, wherein profile positives with spikes positioned in spike holes are provided, in which shallow and elongate depressions as reservoirs for receiving the ice chips that form when the spike scrapes on ice are formed so as to extend in both circumferential directions proceeding from the spike.
Background It is known and conventional for trends of pneumatic vehicle tires to be equipped with spikes in order, under winter driving conditions, to increase the power transmission from the tire to snow-covered and/or ice-covered roadways. The general action of spiked tires is in this case based on several effects. Firstly, spikes penetrate into, and mechanically mesh with, ice situated on the roadway. During braking and traction processes, relative movements (slippage) furthermore occur between the pneumatic vehicle tire and the ice-covered roadway, during which the spikes are pulled through the ice and in the process cut channels into the ice surface. The ice chips ("ice powder") formed in the process commonly collect(s) around the respective spike, whereby both the ice grip action of the spike and the ice grip action of the rubber material of the tread surrounding the spike deteriorate.
To counteract the adverse effects of the ice chips that form, it is known for shallow depressions to be provided, in the immediate vicinity of the spike, as discharge channels or reservoirs for receiving the chips. Such discharge channels or depressions are known in a variety of embodiments.

2 A tire of the type mentioned in the introduction is known for example from WO

Al. The tread of said pneumatic vehicle tire has profile blocks which are equipped with spikes, wherein at least one local, channel-like depression is formed in the region of each spike. The depressions end in each case within the profile block, wherein each depression has a spacing of at most 1.0 cm to the spike hole. The sum of the volumes, in mm3, of the depressions provided around a spike is greater than or equal to the product of the minimum cross-sectional area, in mm2, of that part of the spike pin which projects beyond the tread surface and the length of a depression. The volumes amount to for example in each case 70 mm3. The depressions may be of straight or else curved design, wherein the cross-sectional area of each depression may vary over the profile of the depression, and the cross-sectional area is preferably in each case at its smallest at the spike.
A pneumatic vehicle tire very similar to WO 2009/147047 Al is known from WO

Al. The profile blocks of the tread have spike holes around which in each case channel-like depressions are provided, wherein each channel-like depression opens into a channel that delimits the respective profile block. The sum of the average cross-sectional areas of the provided depressions is greater than or equal to the minimum cross-sectional area of that part of the spike pin which projects beyond the tread surface.
A further pneumatic vehicle tire with a spiked tread is known from WO
2014/123181 Al.
Around each spike hole provided in the tread, there are formed in each case two arcuately running depressions, which are each delimited by two radii relating to the spike axis.
Furthermore, around each spike hole, there is provided a third depression with an arcuate section, the end of which is in each case adjoined by a short straight section which opens in each case into a transverse channel that delimits the profile block.
DE 10 2009 044 547 Al has disclosed a further pneumatic vehicle tire with a spiked tread. The profile blocks of the tread have a depression which surrounds the spike in ring-shaped fashion and from which further channel-like depressions run to the transverse channels that delimit the profile block. The channel-like depressions each have a width of 1.0 mm to 5.0 mm, and each have a depth of 0.5 mm to 1.5 mm. In each case one rib belonging to the profile block is formed

3 between the channel-like depressions. A further pneumatic vehicle tire whose tread has spikes with ring-shaped encircling depressions is known from WO 2013/092434 Al.
If the depressions provided cannot receive the full amount of ice chips that form, the ice chips collect between the tread and the roadway, whereby the meshing of the spikes with the ice does not function optimally, and the ice grip accordingly deteriorates. On the other hand, an unduly large volume of the depressions provided has an adverse effect on the ice grip characteristics of the profile positives of the tread, because depressions of excessively large volume significantly reduce the rubber surface of the profile positives. Since, depending on the type of relative movement between the vehicle tire and ice-covered roadway as mentioned in the introduction, the spikes, depending on load and load direction, cut channels of different length into the ice surface, resulting in different amounts of ice chips, the discharge channels or depressions provided in the region of spikes of the known pneumatic vehicle tires have potential for improvement.
Summary The invention is therefore based on the object, in the case of a tire of the type mentioned in the introduction, of adapting the depressions provided around the spikes and serving as ice reservoirs to the different loads during traction, during braking and during the action of lateral forces in as effective a manner as possible.
The stated object is achieved according to the invention in that the depressions that extend in both circumferential directions are of corresponding design, and in that at least one further depression extends in an axial direction proceeding from the spike, which at least one further depression has or have, in sum total in the case of multiple depressions, a smaller volume than the depression(s) extending in each of the circumferential directions, wherein the depressions extending in both circumferential directions and the at least one depression extending in the axial direction are the only depressions per spike. According to a broad aspect, the invention provides a pneumatic vehicle tyre with a tread, comprising rows of profile blocks or profile strips that are separated from one another by grooves, wherein profile positives with spikes positioned in spike

4 holes are provided, in which, starting from the spike, shallow elongated recesses extending in the two circumferential directions are formed as reservoirs for receiving shards of ice produced when the spike scrapes on ice, wherein the recesses extending in the two circumferential directions are configured to correspond, wherein, starting from the spike, at least one further .. recess extends in the axial direction and, when there are a number of recesses in total, has a smaller volume than the recesses extending in each of the two circumferential directions, and wherein the recesses extending in the two circumferential directions and the at least one recess extending in the axial direction are the only recesses per spike.
The average sliding distances in traction situations and during the transmission of ABS braking forces are relatively great, such that, during such force transmission situations, the channels formed in the ice surface by spikes are at their longest. Since the tire can be mounted on the vehicle in accordance with the two rolling directions ¨ during forward travel ¨ the depressions that extend in both circumferential directions are of corresponding design.
The spikes exhibit, on average, short sliding distances over the ice surface during relative movements that occur as a result of transverse slippage during the transmission of lateral forces.
According to the invention, at least one depression therefore extends from the spike in the axial direction, which at least one depression, in sum total in the case of multiple depressions, has a smaller receiving volume than in each case the depression(s) that extend(s) in one of the circumferential directions.
In the case of the depressions being of the same design in all directions, too large a volume would be available, and the friction power of the rubber surface would be reduced to too great an extent. In the case of depressions designed according to the invention, the volumes are optimally adapted to the amounts of ice chips that form as a result of the different relative movements between spike and ice-covered roadway.
In a preferred embodiment of the invention, the tread is designed such that it can be mounted on the vehicle at any desired axle position and with any desired rolling direction. In the case of such an embodiment, it is advantageous if the depressions extending in the axial direction extend, in .. each tread half, in each case in the direction of the tire shoulder situated closest to the respective spike.

5 A further embodiment of the invention involves a pneumatic vehicle tire, the tread of which is of asymmetrical design and has a defined outer shoulder and a defined inner shoulder and which is to be mounted on the vehicle such that the outer shoulder is situated at the vehicle inner side. For the lateral control characteristics of this embodiment, it is particularly advantageous if all of the depressions extending in the axial direction extend from each spike in the direction of the outer shoulder.
In a preferred embodiment of the invention, the depressions extending in both circumferential directions have a greater extent length than the depression(s) extending in the axial direction. It is therefore also possible for the length of the depressions to be adapted to the corresponding sliding distances of the spikes in the different loading situations.
Optimum receiving and discharging of the ice chips that form on ice is supported or ensured by means of a number of preferred designs of the depressions. These designs include the depression(s) that extend(s) in one of the circumferential directions having, in sum total in the case of multiple depressions, a volume of 12 mm3 to 13.3 mm3. A further advantageous measure in this regard consists in the depression(s) that extend(s) in the axial direction having, in sum total in the case of multiple depressions, a volume of 9.5 mm3 to 10.7 mm3.
As already mentioned, the respective length of the depressions is also of significance for optimum receiving of ice chips. In this context, it is particularly advantageous if the depression(s) that extend(s) in one of the circumferential directions has or have an extent length of 4.9 mm to 5.2 mm, and if, furthermore, the depression(s) that extend(s) in the axial direction has or have an extent length of 3.7 mm to 4.2 mm.
A design is also particularly preferred in which the depressions have, at least over a major part of their extent, a depth of 0.5 mm to 1.0 mm.
Moreover, it is particularly advantageous if the depressions that extend in both circumferential directions are arranged in pairwise fashion and mirror-symmetrically about the same axis of

6 symmetry, wherein the axis of symmetry preferably runs at an angle of -20 to 20 with respect to the circumferential direction.
A design is also preferred in which the depressions that extend from the spike in the axial direction are arranged in pairwise fashion and mirror-symmetrically about an axis of symmetry.
A particularly balanced arrangement of the depressions according to the invention is one in which the axes of symmetry run perpendicular to one another.
Brief description of the drawings Further features, advantages and details of the invention will now be described in greater detail with reference to the drawing, which schematically illustrates exemplary embodiments of the invention. In the figures:
figure 1 shows a plan view of a section of a developed view of a tread of a pneumatic vehicle tire with a design variant of the invention, figure 2 shows an enlarged plan view of a partial region of a profile block, figure 3 shows a section along the line in figure 2, and figure 4 shows a plan view of a section of a developed view of a tread of a pneumatic vehicle tire with a further design variant of the invention.
Detailed description of embodiments Variants, examples and preferred embodiments of the invention are described hereinbelow.
Pneumatic vehicle tires according to the invention are winter tires for passenger motor vehicles, vans or light trucks, with treads that have no preferred rolling direction.
The invention can also be used in the case of tires with treads of asymmetrical design which have different profile 6a structures in the tread halves, such that the tread has one sidewall which is to be assigned to the vehicle outer side when the tire is mounted on the vehicle.
The treads shown in figure 1 and figure 4 each have two shoulder-side block rows 1, l', in each case one middle block row 2, 2' adjoining these, and in the middle tread region, a profile band 3 which runs in encircling fashion in a circumferential direction and which is separated from the middle block rows 2, 2' by in each case one circumferential channel 4, which runs in a straight manner in the exemplary embodiments shown. In the embodiment shown in figure 1, the profile strip 3 runs along and symmetrically with respect to the central line of the tread, and in the embodiment shown in figure 4, said profile strip runs offset with respect to said central line. As a result, the two middle block rows 2, 2 have different axial extent lengths, and the tread is "asymmetrical", that is to say it has a defined outer shoulder A and a defined inner shoulder I. A
tire having a tread of said type is to be mounted on the vehicle such that the outer shoulder A is situated at the vehicle outer side.

7 Slightly arcuate transverse channels 5, 5' run in both tread halves of the embodiments shown in figure 1 and figure 4, which transverse channels extend at an angle of 30 to 60 with respect to the circumferential direction in the region in which they open into the circumferential channel 4, and run substantially in an axial direction in the region of their shoulder-side end. The profile blocks 6a, 6'a of the shoulder-side block rows 1, l' are separated from the profile blocks 6b, 6'b of the respectively adjoining middle block row 2, 2' by oblique channels 7, 7', which run between transverse channels 5, 5' situated adjacently in the circumferential direction.
The profile strip 3 and the profile blocks 6a, 6'a, 6b, 6'b of the block rows 1, l' and 2, 2' are each equipped with sipes, which are in particular designed in a manner known per se.
In the profile blocks 6a, 6b, 6'a, 6'b of the block rows 1, l' and 2, 2' there is furthermore formed in each case one spike hole 8, into which in each case one spike 9, which is composed of a spike body and a spike pin in a manner known per se, is inserted and anchored. Each spike hole 8 has a diameter adapted to the respective spike body.
Figure 2 shows a plan view of a partial region of a profile block 6a from the left-hand shoulder block row 1 in figure 1 and figure 4. The circumferential direction of the tread is denoted by the double arrow U. The spike axis which runs through the center of the spike 9, and which is denoted by al, runs in a radial direction.
Around each spike 9 or each spike hole 8, there are superficially formed elongate depressions arranged in pairwise fashion - two pairs of depressions 10, 10' and one pair of depressions 11, 11' - which serve as reservoirs for receiving the ice chips that splinter off as the tire rolls on an ice-covered underlying surface. Preferably, in the case of each spike 9, the depressions 10, 10' and 11, 11' belonging to a pair are of corresponding design and oriented correspondingly. One pair of depressions 10, 10' extends in one circumferential .. direction proceeding from the spike 9, and the second pair of depressions 10, 10' extends in the other circumferential direction. In each pair of depressions 10, 10', the depressions 10, 10' have, in sum total, a volume VI, and each depression 10, 10' has in each case a length l.

= CA 03000024 2018-03-27

8 The third pair of depressions 11, 11' extends from the spike 9 in the direction of the closest tire shoulder, wherein said depressions 11, 11' have a shorter length 12 and, in sum total, a smaller volume V2. The length li of the depressions 10, 10' is 4.9 mm to 5.2 mm, and the length 12 of the depressions 11, 11' is 3.7 mm to 4.2 mm, where l >12. The total volume Vi of the depressions 10, 10' is 12 mm3 to 13.3 mm3, and the total volume V2 of the depression 11, 11' is 9.5 mm3 to 10.7 mm3, such that Vi > V2.
The volumes VI and V2 of the depressions 10, 10' and 11, 11' are thus adapted to the quantities of ice chips that form as a result of the different relative movements between spike 9 and ice-covered roadway, the depressions 10, 10' to those that form during the transmission of traction power and during the transmission of ABS braking forces, and the depressions 11, 11' to those that form during the transmission of lateral forces. In the design variant shown in figure 1, the depressions 11, 11' in each tread half extend in each case in the direction of the respectively closest tire shoulder. In the embodiment shown in figure 4, all of the depressions 11, 11' extend in the direction of the outer shoulder A.
All of the depressions 10, 10', 11, 11' furthermore have, at least over the major part of their extent, a depth T1 (figure 3) of 0.5 mm to 1.0 mm. The depth Ti may increase or decrease, in particular in continuous fashion, over the length extent of the depressions 10, 10', 11, 11'.
In the design variants shown, all of the depressions 10, 10', 11, 11 adjoin the mold pin insert used during the vulcanization, wherein a very thin rubber skin is normally formed between said mold pin insert and the depressions. The depressions 10, 10', 11, 11' that belong to a pair are designed and arranged mirror-symmetrically with respect to one another with regard to axes of symmetry a2 and a3 running through the spike central point in plan view.
In accordance with their diametric arrangement, the two depressions 10, 10' belonging to a pair are mirror-symmetrical with respect to the same axis of symmetry a/. The axis of symmetry az runs, as illustrated, in the circumferential direction or at an angle of -20 to 20 with respect to the circumferential direction U. The depressions 11, 11' arranged in = CA 03000024 2018-03-27

9 pairwise fashion run mirror-symmetrically with respect to one another about the axis of symmetry ai which, in the preferred design variant shown, runs perpendicular to the axis of symmetry a2.
The depressions 10, 10', 11, 11' arranged in each case in pairwise fashion have in each case a mutual spacing b.! of 0.4 mm to 0.6 mm, in particular of 0.5 mm, at their inner end regions adjacent to the spike 9, wherein, in the design variant shown, the mutual spacing increases in continuous fashion toward the outer end regions of the depressions 10, 10', 11, 11' in each case by up to 1.0 mm, in particular by up to 0.5 mm. The depressions 10,

10, 11, 11' themselves have in each case a width 112 of 1.0 mm to 1.5 mm, in particular 1.25 mm, at their inner end regions situated at the spike 9, wherein the greatest width b3 of said depressions at their outer end regions is 1.5 mm to 2.5 mm.
In a further design variant which is not illustrated, instead of pairs, in each case only one depression is provided, wherein said depressions have volumes Vi and V2 analogously to the embodiment above. The external shape of the depressions may also deviate from that illustrated.

5 List of reference numerals 1, 11 .............. Block row 2,2' ............... Block row 3 ................... Profile strip 4 ................... Circumferential channel .............. 5, 5' Transverse channel 6a, 6b, 6'a, 6'b .... Profile block 7, 7' .............. Oblique channel 8 ................... Spike hole 9 ................... Spike .............. 10, 10', 11, 11' Depression al ................. Spike axis a2, a3 .............. Axis of symmetry b1 ................. Spacing b2 .................. Width .............. b3 Width

11, 1, .............. Length .................... Depth .................... Radial direction .................... Circumferential direction .............. Vi, V2 Volume

Claims (14)

1 . A pneumatic vehicle tyre with a tread, comprising rows of profile blocks or profile strips that are separated from one another by grooves, wherein profile positives with spikes positioned in spike holes are provided, in which, starting from the spike, shallow elongated recesses extending in the two circumferential directions are formed as reservoirs for receiving shards of ice produced when the spike scrapes on ice, wherein the recesses extending in the two circumferential directions are configured to correspond, wherein, starting from the spike, at least one further recess extends in the axial direction and, when there are a number of recesses in total, has a smaller volume than the recesses extending in each of the two circumferential directions, and wherein the recesses extending in the two circumferential directions and the at least one recess extending in the axial direction are the only recesses per spike.

2. The pneumatic vehicle tyre according to claim 1, wherein the recesses extending in the axial direction in each half of the tread respectively extend in the direction of the tyre shoulder located closer to the respective spike.

3. The pneumatic vehicle tyre according to claim 1, wherein the tread is asymmetrically designed and has a defined outer shoulder and a defined inner shoulder and which is to be fitted on a vehicle in such a way that the outer shoulder is on the outer side of the vehicle, wherein all of the recesses extending in the axial direction extend from each spike in the direction of the outer shoulder.

4. The pneumatic vehicle tyre according to any one of claims 1 to 3, wherein the two recesses extending in the two circumferential directions have a greater length of extent than the recesses extending in the axial direction.

5. The pneumatic vehicle tyre according to any one of claims 1 to 4, wherein, when there are a number of recesses in total, the recesses that extends or extend in one of the two circumferential directions has or have a volume of 12 mm3 to 13.3 mm3.

6. The pneumatic vehicle tyre according to any one of claims 1 to 4, wherein, when there are a number of recesses in total, the recesses that extends or extend in the axial direction has or have a volume of 9.5 mm3 to 10.7 mm3.

7. The pneumatic vehicle tyre according to any one of claims 1 to 6, wherein the recesses that extends or extend in one of the two circumferential directions has or have a length of extent of 4.9 mm to 5.2 mm.

8. The pneumatic vehicle tyre according to any one of claims 1 to 7, wherein the recesses that extends or extend in the axial direction has or have a length of extent of 3.7 mm to 4.2 mm.

9. The pneumatic vehicle tyre according to any one of claims 1 to 8, wherein the recesses have at least over the majority of their extent a depth of 0.5 mm to 1.0 mm.

10. The pneumatic vehicle tyre according to any one of claims 1 to 9, wherein the recesses extending in the two circumferential directions are arranged in pairs and mirror-symmetrically in relation to an axis of symmetry.

11. The pneumatic vehicle tyre according to claim 10, wherein the axis of symmetry runs at an angle of -20° to 20° in relation to the circumferential direction.

12. The pneumatic vehicle tyre according to any one of claims 1 to 11, wherein the recesses extending in the axial direction from the spike are arranged in pairs and mirror-symmetrically with respect to an axis of symmetry.

13. The pneumatic vehicle tyre according to any one of claims 10 to 12, wherein the axes of symmetry run perpendicularly in relation to one another.

14. The pneumatic vehicle tyre according to any one of claims 1 to 13, wherein the recesses end within the profile positive.