IE42126B1

IE42126B1 - Tyre tread

Info

Publication number: IE42126B1
Application number: IE181975A
Authority: IE
Original assignee: Dunlop Ltd
Priority date: 1974-08-27
Filing date: 1975-08-18
Publication date: 1980-06-04
Also published as: BE832719A; IT1042071B; DK382775A; NL7509916A; JPS5150104A; FR2283018A1; GB1524364A; AU8423275A; FR2283018B1; LU73249A1; DE2441063A1; JPS5824282B2; IE42126L

Abstract

1524364 Tyre treads DUNLOP Ltd 13 Aug 1975 [27 Aug 1974] 33676/75 Heading B7C A tyre tread shown schematically in Fig. 1 comprises a plurality of blocks arranged in rows 5, 6, 7, 8 which extend in the longitudinal direction of the tread, said blocks when considered in plan view each comprising a rectangular part and an adjoining trapezoidal part, a longer side of the rectangular part of the blocks in the row 8 lying alternately transversely to and parallel to the longitudinal direction.

Description

This invention relates to a tyre tread having several rows of blocks which extend in the longitudinal direction of the tread.

More especially, the invention relates to a tread most suitable for a winter tyre.

It is known that the demands made on a vehicle pneumatic tyre to yield good properties both on dry and also wet, icy roads covered with loose snow or partially melted snow, tend to be contradictory. Also since so-called studded tyres can no longer generally be used on account of the damage they cause to road surfaces, there is a need for a vehicle tyre 10 which can replace the customary studded tyres, and which has, at least in certain road conditions, even better properties.

In accordance with the invention a tyre tread is formed with a plurality of blocks arranged in rows which extend in the longitudinal direction of the tread, said blocks when considered in plan view each comprising a rectangular part and a trapezoidal part lying transversely of the 2. 42136 rectangular part, a longer side of the rectangular part of the blocks in a row adjacent a side region of the tread lying alternately transversely to and parallel to the longitudinal direction.

Preferably a side of the trapezoidal part of a block, which is not parallel to another side of the said part, has at least a portion of its length alongside a similar side of the trapezoidal part of another block.

The longitudinal and/or transverse dimensions of the individual blocks are preferably varied along the length of the tread. This variation has an advantageous effect with regard to noise suppression.

A zig-zag shaped groove is preferably formed between adjacent rows of blocks which are positioned on the same side of the longitudinal centre line of the tread. This zig-zag groove preferably has serrated sections which produce particular gripping properties for the tread. The serrated sections are caused by the fact that the sides of the trapezoidal parts of the blocks,which lie alongside the groove and are not parallel to one another,are preferably formed with steps as viewed in plan. The surfaces of the steps may extend parallel and transversely to the longitudinal centre line of the tread and this arrangement is advantageous?especially when the tread is used on snow-covered roads.

Preferably at least one of said steps is provided with a narrow slot which extends therefrom into the block and which may be straight, curved, stepped or toothed in design.

The provision of these slots causes the longitudinal or transverse forces which are applied to the tread in use and which are absorbed by the edges of the trapezoidal parts of the block to be transferred diagonally into the body of the block. In addition these narrow slots improve the adaptability of the tyre to different road conditions. 3.

Preferably a plurality of narrow slots may be formed in those edges of the blocks which extend transversely to the longitudinal centre-line of the tread. These narrow slots may be different in depth from the or each narrow slot which extends from a step in the block and each one may extend substantially at right angles to the block edge in which the slot is formed. These narrow slots not only make the transverse edges softer, but prevent sudden impacts thereof with a consequential reduction in noise. Further, these narrow slots contribute to the adhesion of the tyre tread in the transverse direction.

The blocks may each be provided with a plurality of narrow slots which do not extend to an edge thereof, and which are different in depth (a) from the narrow slots provided in those edges of the blocks which extend transversely of the longitudinal centre line?or (b) from the or each narrow slot which extends from a step formed in the block.

At least one of the blocks may be provided in the rectangular part thereof with a blind groove which extends transversely to the longitudinal direction of the tread. Part Of the blind groove may be of a different depth from the remainder thereof. Preferably the blind groove extends from the region of the centre of, and is shorter than, a side of the rectangular part of the block which extends transversely to the longitudinal direction of the tread. The blind groove affects the flexibility of the block in which it is formed so that the block can absorb longitudinal and transverse forces effectively.

Preferably the blind groove separates the side of the block from which it extends into two regions which are parallel to and staggered in relation to one another. The sum of the staggering of the said regions may be approximately equal to the length of the blind groove. 4. 312 6 A row of blocks may be provided adjacent the longitudinal centre-line of the tread, the rectangular part of each block in said row being between the trapezoidal part and the centre-line, with a longer side of the rectangular part of the blocks extending parallel to said centreline. Preferably two such rows are provided, one row being situated on one side of the centre-line, the other row being on the opposite side, the blocks being arranged in pairs, one block from one row being immediately transversely opposite a block from the other row, the blocks in each pair being of equal longitudinal extent.

Preferably each pair of blocks is provided with two mutually transversely aligned blind grooves, one in each block, the blind grooves each extending from that side of each block which is immediately adjacent the other block in the pair. Each blind groove may separate the side of the block in which it is formed into two regions which are parallel to and staggered in relation to one another.

Preferably between the two rows of blocks each immediately adjacent the tread centre line is a longitudinal groove having sections staggered alternately towards one side of the tread and the other. A straight continuous longitudinal groove part may be provided between the inner rows of blockswhich is narrow as compared with the overall width of the longitudinal groove which comprises the staggered sections.

Alternately a longitudinally extending rib may be positioned along the longitudinal centre line of the tread between two rows of blocks, said rib having trapezoidal projections which extend alternately towards one side of the tread and the other.

Preferably a tyre tread in accordance with the invention comprises four longitudinally extending rows of blocks, two rows on each . side of the longitudinal centre line of the tread, and further, comprises a rubber composition having good ice-adhering qualities.

Two embodiments of the invention will now be described in detail by way of example with reference to the accompanying schematic drawings, in which: Figure 1 shows a plan view of part of the pneumatic tyre tread of the first embodiment, and Figure 2 shows a plan view of part of the pneumatic tyre tread of the second embodiment.

In Figure 1 the tread is distinguished by the reference number 1 and the side regions by the reference numbers 2 and 3, Provided on both sides of the longitudinal centre line 4-4 are respectively two longitudinally extending rows of tread blocks, namely respectively, inner rows of blocks 5, 6 which lie adjacent the centre line 4-4 and outer rows of blocks 7, 8 which lie adjacent the side regions of the tread.

The individual blocks of the different rows of blocks are, in principle, of the same shape, i.e. they comprise, when considered in plan view, a rectangular part 9 and a trapezoidal part 10. The sides of the trapezoidal part 10 which are not parallel are formed with steps 11 as viewed in plan. The individual steps 11 each consist of two surfaces, one extending parallel to the longitudinal centre line of the tread and the other transversely thereto. Straight, curved, stepped or zig-zag shaped narrow slots 12 extend from some of the steps approximately diagonally into the block.

Further narrow slots 13, are formed in those edges of the blocks which extend transversely of the centre line 4-4 of the tread. . 43126 Moreover, the blocks are.also provided with a plurality of narrow slots 23 which are preferably curved, which do not extend in the block edges and extend substantially transversely towards the centre line of the tread.

The three different sorts of narrow slots i.e. those extending from steps, those extending from a transversely extending block edge and those not extending to a block edge may be of different depths to each other.

Provided on the side of the rectangular part of each 10 block which lies opposite the trapezoidal part 10 is a blind groove T4.

The depth of the individual blind grooves can be different, and it is also possible to vary the depth of one blind groove in the course of its length.

The length of the blind grooves 14 is generally somewhat less than the length of the edge of the rectangular part 9 which extends parallel to the centre plane 4-4 and from which the blind groove extends.

The blocks of the inner rows 5, 6 are arranged in pairs, one block from one row 5 being immediately transversely opposite a block from the other row 6, and the longer edges of the rectangular parts lie immediately adjacent one another on opposite sides of the centre line 4-4.

The blocks in each pair are of equal longitudinal extent, and the blind grooves of opposed blocks are transversely aligned with one another. Each blind groove separates the block edge in which it is formed into two regions which are staggered in relation to one another, so that in each of the pairs of blocks in the two inner rows 5, 6 a projecting region and a staggered25 back region lie opposite one another respectively, whereby a longitudinal centre groove 19 which comprises staggered sections is obtained. The mutual spacing of the blocks of the rows of blocks 5 and 6 is selected, as 7. shown in Figure 1 in such a way that there arises, in the centre of the groove,regions which are otherwise staggered to one side of the tread and to the other, in addition a straight continuous longitudinal groove which is narrow as compared with the overall width of the longitudinal groove which comprises the staggered section. The straight groove contributes to the road holding. However, it is also possible to select a smaller mutual spacing of the blocks of the rows of blocks 5, 6, so that a straight continuous groove is no longer present.

Two zig-zag-shaped grooves 20 are formed, one on each side of the longitudinal centre line 4-4 between the respective inner rows of blocks 5, 6 and the outer rows of blocks 7, 8. Since the individual blocks of the inner and outer rows of blocks are arranged to overlap one another so that the stepped regions of the non-parallel trapezoidal side surfaces lie opposite one another, this zig-zag-shaped groove 20 has serrated sections in the regions between the steps on the blocks of the inner and outer rows.

The width of the serrated sections of the grooves 20 between the stepped side surfaces is advantageously smaller than the width of a connecting region adjacent a side 15 of the trapezoidal part of a block in an outer row 7, 8 and between two such serrated sections of the groove 20.

The outer rows of blocks 7, 8 each Tie immediately adjacent one of the side regions 2, 3. Each block in the outer rows has a rectangular part and a trapezoidal part, an edge of the rectangular part extending parallel to the longitudinal centre line 4-4. The edges 16 of alternate blocks lie on a first imaginery line parallel to the centre line, and are each divided into two longitudinally aligned sections by a blind groove 14. The edges of remaining blocks also lie parallel to but are 8. spaced nearer to the tread centre line 4-4 than the edges 16. The remaining blocks are also divided into two sections lying parallel to the centre line by a blind groove, but the two sections are not in longitudinal alignment but are mutually staggered.

Lying transversely outward of each of said remaining blocks is a further block 28 comprising a rectangular part and a trapezoidal part, the trapezoidal part being further from the tread centre line than the rectangular part and the edges 16 of the alternate blocks. The non-parallel sides of the trapezoidal parts are formed with steps, leading from at least one of which is a narrow slot. Narrow slots which do not extend to the block edges are also provided in the said further blocks.

The further blocks 28 areseparated from the immediately adjacent remaining block by a longitudinally extending groove 27 which consists of groove sections which are staggered towards one side of the tread and the other.

Each further block 28 is provided with a transversely extending blind groove which is in alignment with the blind groove in the immediately adjacent remaining block.

When the tread is on a tyre there is provided in the zone of the highest ground pressure an edge which extends parallel to the longitudinal direction of the tread thus ensuring good road holding properties. At the same time, the trapezoidal parts of the said further blocks which project into the shoulder regions 2, 3, which are formed with steps and which have a rounded profile are advantageous when the tyre encounters protrusions on the road surface.

The embodiment in accordance with Figure 2 differs from the tread shown in Figure 1 in that a longitudinally extending rib 24 is provided in the centre of the tread. This embodiment is intended for tyres of larger sizes. 9.

The rib 24 which lies along the longitudinal centre line 4-4 between the inner rows of blocks 5, 6 has trapezoidal projections 25 which extend alternately towards one side of the tread and the other.

The non-parallel sides of the trapezoidal projections are formed with steps as viewed in plan. The width of the trapezoidal projections 25, measured transversely of the tread, is generally less than the correspondingly width of the trapezoidal parts of the individual blocks. Some of the steps are each provided with a narrow slot which extends substantially diagonally into the rib i.e. obliquely to the longitudinal direction. In addition, substantially transversely-extending narrow slots 26 which do not extend to a rib edge are also formed in the rib 24.

The trapezoidal projections 25 which extend alternately to one side and to the other, lie opposite respectively staggered-back edge region of the individual blocks of the row of blocks 5, 6. The grooves on each side of the rib have staggered sections similar to the central groove 19 of the tread shown in figure 1 and can have a width such that a narrow straight continuous longitudinal groove is provided as with the groove 19 of the tread shown in Figure 1.

The tread in accordance with the invention is preferably formed from a comparatively soft rubber composition which gives good ice adhesion properties. The advantageous properties of such a composition, more especially in winter operation, optionally complement the particular properties of the tread.

Claims

1. A tyre tread formed with a plurality of blocks arranged in rows which extend in the longitudinal direction of the tread, said blocks when considered in plan view each comprising a rectangular part and a trapezoidal part lying transversely of the rectangular part, a longer side of the

2. A tyre tread according to Claim 1 wherein a side of the trapezoidal part of a block, which is not parallel to another side of said part, has at least a portion of its length alongside a similar side of the trapezoidal part of another block.

3. A tyre tread according to Claim 1 or 2 wherein the longitudinal and/or transverse dimensions of the individual blocks are varied along the length of the tread.

4. A tyre tread according to any one of the preceding claims, wherein a zig-zag-shaped groove is formed between adjacent rows of blocks which are positioned on the same side of the longitudinal centre line of the tread. 5. 5 lying parallel to the centre-line and the said edges of remaining blocks in the row also lying parallel to, but spaced nearer to the centre-line than the said edges of the said alternate blocks.

5. A tyre tread according to any one of the preceding claims wherein the sides of the trapezoidal parts which are not parallel to each other are formed with steps as viewed in plan.

6. A tyre tread according to Claim 5, wherein at least one of said steps is provided with a narrow slot which extends therefrom into the block.

7. A tyre tread according to Claim 6. wherein the or each narrow slot is straight, curved, stepped or toothed in design.

8. A tyre tread according to any one of the preceding claims, wherein a plurality of narrow slots is formed in those edges of the blocks which extend transversely to the longitudinal centre-line of the tread.

9. A tyre tread according to any one of ciaims 5, 6 or 7 wherein a plurality of narrow slots is formed in those edges of the blocks which extend transversely to the longitudinal centre-line of the tread, and which are different in depth from the or each narrow slot which extends from a step formed in the block. 10. Comprising a rectangular part and a trapezoidal part.

10. A tyre tread according to Claims 8 or 9 wherein each one of the plurality of narrow slots extends substantially at right angles to the block edge in which the slot is formed. 10. rectangular part of the blocks in a row adjacent a side region of the tread lying alternately transversely to and parallel to the longitudinal direction.

11. A tyre tread according to any one of the preceding claims, wherein the blocks are each provided with a plurality of narrow slots which do not extend to an edge thereof. 11. 12. 42136

12. A tyre tread according to Claims 8 or 9, wherein the blocks are each provided with a plurality of narrow slots which do not extend to the block edges and which are different in depth from the narrow slots provided in those edges of the block which extend transversely of the longitudinal centre-line. 13.

13. A tyre tread according to Claim 5, 6 or 7 wherein the blocks are each provided with a plurality of narrow slots which do not extend to the block edges and which are different in depth from the or each narrow slot which extends from a step formed in the block. 14.

14. A tyre tread according to any one of the preceding claims, wherein at least one of the blocks is provided with a blind groove which extends transversely to the longitudinal direction of the tread. 15.

15. A tyre tread according to Claim 14, wherein at least a part of the blind groove has a different depth from the remainder thereof.

16. A tyre tread according to Claim 14 or 15, wherein the blind groove is provided in the rectangular part of the block.

17. A tyre tread according to Claim 16, wherein the blind groove extends from, and is shorter than, a side of the rectangular part of the block which extends parallel to the longitudinal direction of the tread.

18. A tyre tread according to Claim 17, wherein the blind groove is provided in the region of the centre of that side of the rectangular part of the block from which the groove extends.

19. A tyre tread according to Claim 17 or 18, wherein the blind groove separates the side of the block from which it extends into two regions which are parallel to and staggered in relation to one another.

20. A tyre tread according to Claim 19, wherein the sum of the staggering of the block side regions separated by the blind groove is approximately equal to the length of the blind groove.

21. A tyre tread according to any one of the preceding claims, wherein a row of blocks, is provided adjacent the longitudinal centre-line of the tread, the rectangular part of each block in said row being between the trapezoidal part and said centre-line.

22. A tyre tread according to Claim 21, wherein a longer side of the rectangular part of the blocks adjacent to the centre line extends parallel to said centre-line.

23. A tyre tread according to any one of claims 1-13, comprising two rows of blocks, one row being situated on one side of the longitudinal centre-line of the tread, the other row being on the opposite side, the blocks being arranged in pairs, one block from one row being immediately transversely opposite a block from the other row, the blocks in each pair being of equal longitudinal extent.

24. A tyre tread according to Claim 23 wherein each pair of blocks is provided with two mutually transversely aligned blind grooves one in each block, the blind grooves each extending from that side of each block which is immediately adjacent the other block in the pair. 25. Claims, comprising a rubber composition having good ice-adhering qualities.

25. A tyre tread according to Claim 24, wherein each blind groove separates the side of the block in which it is formed into two regions which are parallel to and staggered in relation to one another.

26. A tyre tread according to any one of Claims 22-24, wherein between the two rows of blocks each immediately adjacent the tread centre-line is a longitudinal groove having sections staggered alternately towards one side of the tread and the other.

27. A tyre tread according to any one of Claims 22-25, comprising a straight continuous longitudinal groove part between the inner rows of blocks which is narrow as compared with the overall width of the longitudinal groove which forms the staggered sections.

28. A tyre tread according to any one of the preceding claims, comprising four longitudinally extending rows of blocks, two rows on each side of the longitudinal centre-line of the tread.

29. A tyre tread according to any one of Claims 23-28 wherein a longitudinally extending rib is positioned along the longitudinal, centre-line of the tread between two rows of blocks, said rib having trapezoidal projections which extend alternately towards one side of the tread and the other.

30. A tyre tread according to Claim 29, wherein the rib is formed with narrow slots which extend transversely of the longitudinal direction.

31. A tyre tread according to Claim 29 or 30, wherein the non-parallel sides of the trapezoidal projections are formed with steps as viewed in plan.

32. A tyre tread according to Claim 31, wherein the steps in the rib are each formed with a narrow slot which extends into the block obliquely to the longitudinal direction of the tread.

33. A tyre tread according to any one of the preceding claims, comprising two side regions, adjacent each of which is a row of blocks, each block in said row having an edge extending parallel to the longitudinal centre-line of the tread, the said edges of alternate blocks

34. A tyre tread according to Claim 33, wherein lying transversely outwards of each of said remaining blocks is a further block

35. A tyre tread according to Claim 34, wherein said trapezoidal part lies further from the longitudinal centre-line of the tread than the rectangular part and the said edges of the said alternate blocks. 15

36. A tyre tread according to Claim 34 and 35, wherein the non-parallel sides of said trapezoidal part of each said further blocks are formed with steps when viewed in plan.

37. A tyre tread according to Claim 36, wherein each of said further blocks is formed with narrow slots. 20

38. A tyre tread according to any one of Claims 34-37, wherein said further blocks are separated from said remaining blocks by a longitudinally extending groove which consists of groove sections which are transversely staggered towards one side of the tread and the other.

39. A tyre tread according to any one of the preceding

40. A tyre tread substantially as described herein with reference to and as illustrated in Figure 1 of the accompanying drawings.

41. A tyre tread substantially as described herein with reference to and as illustrated in Figure 2 of the accompanying drawings.

42. - A tyre having a tread according to any one of the preceding claims.