WO1996015002A1

WO1996015002A1 - A tread and a tyre including the tread

Info

Publication number: WO1996015002A1
Application number: PCT/FI1995/000611
Authority: WO
Inventors: Erkki Antero Myllyharju
Original assignee: Erkki Antero Myllyharju
Priority date: 1994-11-10
Filing date: 1995-11-09
Publication date: 1996-05-23
Also published as: FI96934B; FI96934C; AU3807395A; FI945286A0

Abstract

A tyre tread (2) according to the present invention comprises a plurality of suction pad means (3) being adapted to deepen in essentially the same proportion as the wear of the tread. The suction pad means (3) are formed by portions (7) defined by grooves (6) of the tread. The portion (7) is preferably arranged such that each edge of the portion yields or flexes more easily against a pressure caused by a road surface than the center of the portion. As a consequence, a greater and more abrading pressure is caused to the center of the portion than to the edge areas thereof, and thus the portion will be abraded at the center rather than at the edge areas.

Description

A tread and a tyre including the tread

The present invention relates to a tread, e.g. to a tread for a tyre, according to the preamble of claim 1 . Such tyres including the tread are used, for instance, in vehicles, such as cars, motorcycles and tractors. In accordance with the invention, the tread, e.g. the running surface of a tyre is improved such that the friction i.e. the holding power between the tread and a slippery surface, e.g between a tyre and a slippery road surface, increases.

In the prior known tyres frictional properties are provided by means of different rubber grades or compositions thereof and by different types of tread patterns. The rubber grade is altered during the manufacture of the tyre according to the conditions and purpose of use of the tyre by altering the chemical formula of the raw material of the tyre. A grip to a soft road surface is chiefly obtained by formulating the pattern of the grooves of the tyre. A durability of sharpness in one side of a portion of the tread is chiefly obtained by inclining the pattern.

However, the prior known tyres have not operated satisfactorily, for instance, in view of gripping properties, vehicle behavior and thus in view of safety, drive noise, rolling friction and wearing rate. Thus there is a long felt need, for instance among drivers, for tyres with improved treads.

So called special winter tyres intented for winter use and/or for icy or snowy roads are also prior known. In said winter tyres particular studs are used for protruding from the tread of the tyre. Said studs are usually made of a suitable metal composition. Said studs can also be of any other suitable material.

A major disadvantage of the present winter tyres is the road surface erosion caused by the studs, which causes significant road maintenance costs and rutting of the roads, thereby exposing the traffic to danger. The amount and the contact force of the metallic studs of the tyres has been decreased to prevent the erosion of the roads, which has caused a simultaneous decrease in the friction between the tyre and the road surface. The metallic studs cause a need for a tyre change according to seasons and road conditions, and thus the vehicle needs at least two different sets of tyres. The metallic studs cannot be used in all kinds of heavy vehicles since in case of heavy load they are not firmly retained in the tyre.

In certain road conditions the slipperiness of the road can be removed by salting, but the salt softens the pitch of the asphalt and thus the erosion of the road is further increased. The loosened pitch and the salt make vehicles dirty and pollute the environment. There are also roads which are not salted, and thus these roads are even more slippery when driving with tyres having pitch and salt on them and made by the present known techniques.

The worst disadvantage of the present tyres intented for summer use is that in wet conditions the tyres rise off from the road surface and start to hydroplane, even at a substantially low speed and/or on a substantially thin moisture film. In some cases the shape of the grooves of the tyre may even boost the hydroplaning. When driving on fine sand or on even-grained sand with the present ordinary tyre, the tyre very easily starts to dig into the sand. The same occurs when driving on a soft and/or argillaceous ground or in a road of that kind.

The objective of the present invention is to overcome the disadvantages of the prior art treads, e.g. tyre treads and similar means and to provide a totally new solution to improve safety, reliability, abrasion resistance and running comfort of articles including a tread, such as tyres, ordinary belts, belts for motor sleds and similar means. According to the solution of the present invention, a tyre tread or similar tread is provided which has good frictional properties acting against slipping, while a rolling friction of said tyre tread or similar relative to the road surface or similar is advantageous to, for instance, provide an economical movement of the vehicle using the tyres.

A further object of the present invention is to provide a tyre tread intented for winter use which erodes the road surfaces essentially less than the prior art winter tyres.

A still further object of the present invention is to provide a tyre tread which is suitable for use throughout the year independently of the road conditions.

It is characteristic for a tread according to the present invention that the tread is provided with a plurality of suction pad means which will deepen essentially at the same rate with the abrasion of the tread of the tyre such that said suction pad means essentially maintain the suction pad like shape thereof until the grooves of the tread are lowered to the end of their allowance of wear.

According to one embodiment it is characteristic for the suction pad means of the tread that one single suction pad means is provided by a portion defined by the grooves of the tread, said portion comprising a cone expanding in a direction outwards from the tread surface or otherwise being shaped such that each edge of the portion allows the edge to yield, i.e. to flex, more than the center of the portion yields against the pressure caused by the road surface. As a consequence, a greater and more abrasive pressure by the road surface is provided into the center of the portion than to the edge areas, and thus the portion will wear at its center rather than at the edge areas.

According to one embodiment the suction pad means of the tread are characterized in that the edge of the suction pad means is formed of a tread material which is of a more flexible or more wear-resistant rubber-like material than the inner portion of the suction pad means.

According to another embodiment the suction pad means of the tread are characterized by having tubular sleeves embedded into the portions defined by the grooves of the tread, or by having portions which are covered by sleeves forming the edge of the suction pad means and which are of a more flexible or more wear-resistant rubber-like material than the tread itself.

According to another embodiment it is characteristic for the suction pad means of the tread that a portion, by which the suction pad means is provided, is formed by several partial portions or lamellas. The edge of the suction pad means is formed by the outer edges of the partial portions. The partial portions are disposed essentially close to each other.

According to a further embodiment it is characteristic for the suction pad means of the tread that the partial portions or lamellas forming the portions can also be independent suction pad means according to the invention such that said partial portions or lamellas are cone-like sleeves disposed within each other or such that separate lamellas together, within each other or beside each other, form the suction pad means. According to a further embodiment, the suction pad means of the tread comprise a portion formed by sleeve-like partial portions. Said partial portions or sleeves may also be straight at the sides thereof, whereby the edges of the whole portion yields more easily along the splittings of the partial portions or sleeves than the core of the portion yields. Thus the edges of the suction pad means wear even more slowly, and the straight partial portions or sleeves of the core wear faster, since they bear more steadily against the road surface than the outermost portion sleeve inclined at the outer edge thereof.

More precisely, a tread according to the present invention is mainly characterized by what is disclosed in appended claims 1 to 14 and especially by the characterizing portion of claim 1 . A tyre according to the present invention is especially defined by claim 1 2.

Significant advantages are obtained by the present invention. For example, by providing an ordinary tyre with a tread according to the present invention, an essential improvement in the grip between the tyre and a road surface is achieved, for instance in weather and road conditions having an especially high risk for so called hydroplaning. Furthermore, the wear-resistance of the tyre is improved, which has effects in view of the economy of the tyre and also in view of the safety of the tyre, since a situation in which a tyre is "over-worn" occurs at longer intervals due to a longer duration of the tyre. In view of winter use, one of the most important advantages is that the tyre does not require any metallic studs or similar means.

The sharp edge of the suction pad means wipes the water off during a slipping of the tyre and grips or cuts into a road surface formed by snow, slushy snow, sand, clay or mud, and thus an improved grip preventing the slipping of the tyre in all directions is obtained.

In the following the present invention and the objects and advantages thereof will be described by way of an example with reference to the annexed drawing, in which similar reference characters throughout the various figures refer to similar features. It should be understood that the following description of an example of the invention is not meant to restrict the invention to the specific forms presented in this connection but rather the present invention is meant to cover all modifications, similarities and alternatives which are inclu- ded in the spirit and scope of the present invention, as defined by the appen¬ ded claims.

Figure 1 shows a side view of a vehicle tyre.

Figure 2 is a schematic sectional view of a tyre tread according to the present invention.

Figure 3 is a schematic sectional view of a tread according to a further embodiment of the present invention.

Figure 4 is a schematic sectional view of a tread according to a still further embodiment of the present invention.

Figure 5 is a schematic sectional view of a tread according to the present invention, being a modification of the embodiment shown in Figure 2.

Figure 6 is a schematic top view of the tread shown in Figure 5.

Fig. 1 discloses a side view of a tyre 1 for a vehicle. A suitable tread 2 is provided on the circumferential surface of the tyre 1 .

Fig. 2 discloses a cross section of a tread 2 of a tyre, in which two alternative, simple forms of suction pad means are shown. The suction pad means 3 are shown as being formed by a portion 7 defined by grooves 6 of the tread 2, said portion preferably being formed as a cone expanding in the radially outwardly extending direction of the tyre 1 , or otherwise being formed such that each edge of the portion 7 yields or flexes more easily against the bearing pressure caused by the road surface than the center of said portion. A proper depth and shape of the suction pad means 3 is provided by the steepness and/or shape of the conicality of the portion 7. As the conicality increases, the suction pad means 3 will become deeper. During use, as the tyre wears until the end of the tread, an improved duration of the shape of the suction pad means 3 is achieved when the conical section of the portion 7 has a cross section having a curved shape or a shape of a partial ellipse.

Fig. 3 discloses a cross section of a tread 2 showing two different forms of a portion 7. A further portion 9 of a rubber like material is disposed in the center of each of the portions 7. Said rubber like material is more abrasive than the tread 2. Since the further portion 9 is more easily abraded than the tread, it will more easily and in a more controlled manner provide the depth and the shape of the suction pad means 3 of the present invention. The further portion 9 may also be more rigid than the tread 2, by means of which the portion 7 can be made more solid and the driving properties of the tyre can be altered. The more rigid center part 9 of the suction pad means 3 enhances also the duration of the sharpness of the edge of the suction pad means 3.

The center part 9 of the suction pad means 3 can be introduced as a completed piece during the vulcanization of the tread 2 of the tyre. Alternatively, the tread 2 can also be completely vulcanized first, while leaving openings for the portions 9 in the tread. Said openings are then filled with a rubber like material which is attached by vulcanization into the tread 2. The further portions 9 can also be made simultaneously with the vulcanization of the tread 2, for example by extruding through a mould. Various chemicals as well as heat can also be utilized when forming the embedded portions 9.

Fig. 4 discloses a cross section of a tread 2 and more precisely, shows three alternative modifications of the portions 7 according to invention. On the right hand side a pipe like sleeve 8 is embedded inside a portion 7 defined by grooves 6. As can be seen from the left hand side and the middle portions, the portions 7 can alternatively be coated by sleeves 10, which form the edges of the suction pad means 3 and are of a more flexible or more wear-resistant rubber-like material than the tread material in general.

The sleeves 8 and 10 can be mounted in a similar manner as the portions 9 of Fig. 3. The sleeves 8 and 10 and neutral portions 9 can be attached to tight openings or guide supports by means of friction. The surfaces of the sleeves 8 and 10 and portions 9 and the openings or guide supports can also be provided with claws and cavities or notches. The cross sections of the sleeves may have various shapes and the sleeves may have more than one opening, i.e. they may have a honeycomb structure.

Fig. 5 discloses a cross section of a tyre tread 2, wherein portions 7 defined by grooves 6 of the tread 2 and forming a suction pad means 3, are formed by a plurality of partial portions or lamellas 1 1 . In this embodiment the suction pad means are formed by the outer edges of the partial portions or lamellas 1 1 . The partial portions 1 1 of said plurality of portions are disposed essentially adjacent to each other. Said partial portions are separated by splittings or slots 4 and 5. Said slots separating the partial portions 1 1 may be essentially normal or at an angle relative to the tread of the tyre. In addition, these slots 4 and 5 separating the partial portions 1 1 can be of various depths and differently shaped, for example in a similar manner as is shown in Fig. 2 showing different outer edges of the suction pad means, i.e. the shapes of the grooves 6.

Fig. 6 discloses a top view of the tread 2 having portions 7 defined by grooves

6 and formed by partial portions 1 1 or 1 2. The partial portions 1 1 on the left side are separated by a splitting or slot 4. Fig. 6 shows one example of the shape of said splitting or slot, but other suitable shapes are also possible. One portion 7 may be provided with a suitable amount of partial portions 1 1 and/or

1 2, which in turn can be arranged to form different patterns. The partial portions of one portion can also be differently sized and shaped. The portions

7 can also be arranged to form different tread patterns. Furthermore, it is not necessary for the splitting 4 to extend to the outer edges of the portion 7, but it can comprise a partial splitting extending inside the portion 7 only. The splittings can also separate partial portions 1 1 inside the total portion 7.

Differently shaped rings, as shown by partial portions 12, can be formed from the partial portions. When the splittings 5 are inclined, i.e. they form expanding cones in a direction outwards from the tread, they form separate suction pad means disposed within each other in the portion 7. One or several of these groups of within each other disposed suction pad means 1 2 can be disposed within a single portion 7. In case one portion includes several groups of suction pad means such groups can be placed side by side or they can be aligned in any other suitable manner.

The above description discloses some examples of forming the suction pad means 3 according to the present invention, but other means can also be used without departing from the scope of the appended claims.

Tyres provided with a tread according to the present invention can be used as winter tyres and summer tyres. A good grip on a snowy, slushy or icy road surface is obtained by a winter tyre according to the present invention. When used as a summer tyre, advantages are obtained in preventing hydroplaning as well as slipping on soft roads or in cross-country conditions. In some cases it might be preferred to provide a tyre according to the present invention, and especially a winter tyre according to the present invention, with suitable additional anti-skid means, whereby a good grip is obtained even in extremely bad conditions.

The suction pad means of the tread according to the invention may be combined with a conventional tread and portion pattern. In the plane of the tread the shape of the suction pad means, as well as the shapes of the portion patters, may be of any possible shape. According to the purpose of use the portion pattern may, for example, extend continuously around the whole periphery of the tyre. The portions in which the suction pad means are formed can be supported by suitable means or attached to each other by suitable means.

The groove 6 defining the portions 7 can be partially a conventional groove whereby complete suction pad means are not formed. The same applies when the portion 7 is a continuous ring extending around the periphery of the tyre. In most cases, when the portion 7 borders to the edge of the tread, it will be conventionally shaped at the outer edge thereof.

The present invention as defined in the appended claims can also be applied to other areas of technology where a good grip against a slippery and/or loose surface is required, without departing from the scope of the invention. One such area of use is in various belts, such as drive belts for motor sleds and similar vehicles, and drive belts of various machines.

Claims

1 . A tread (2) for a tyre ( 1 ) or similar means, c h a r a c t e r i z e d in that said tread comprises a plurality of suction pad means (3), wherein each of said suction pad means (3) is adapted to deepen in an essentially equal proportion to the wear of said tread (2).

2. A tread according to claim 1 , wherein said suction pad means (3) are formed by a portion (7) defined by a groove (6) of said tread (2), said portion comprising a cone expanding in a direction outwards from said tread (2).

3. A tread according to claim 1 , wherein said suction pad means (3) are formed by a portion (7) defined by a groove (6) of said tread (2) , said portion being adapted such that each edge of said portion (7) yields or flexes more easily against the pressure caused by a surface bearing against said tread than the center of said portion.

4. A tread according to claim 1 , wherein the edge of said suction pad means (3) is formed by a tread material that is of a more flexible and/or more wear-resistant rubber-like material than the inner part (9) of said suction pad means.

5. A tread according to any of the preceding claims, wherein pipe-like sleeves (8) are embedded into portions (7) forming said suction pad means (3) and being defined by grooves (6) of said tread (2), said sleeves (8) being of more flexible and/or more wear-resistant rubber-like material than said tread (2) .

6. A tread according to any of claims 1 to 4, wherein portions (7) forming said suction pad means (3) and being defined by grooves (6) of said tread (2) are covered with sleeves ( 10) forming the edges of said suction pad means, said sleeves ( 10) being of a more flexible and/or more wear-resistant rubber-like material than said tread (2) .

7. A tread according to claim 1 , wherein said suction pad means are formed by several partial portions or lamellas ( 1 1 ), the edges of said suction pad means (3) being formed by the outermost edges of said partial portions.

8. A tread according to claim 1, wherein a portion (7) forming said suction pad means (3) is formed by partial portions or lamellas (12) such that said partial portions or lamellas comprise cone-like sleeves which are placed within each other and expand in a direction outwards from said tread, whereby each of said partial portions or lamellas forms an independent suction pad (3).

9. A tread according to claim 1, wherein a portion (7) forming said suction pad means (3) is formed by partial portions or lamellas (12) such that said partial portions or lamellas comprise pipe-like sleeves placed within each other, said sleeves being preferably adapted to have mutually different shapes.

10. A tread according to claim 8 or 9, wherein said partial portions (12) can be split to form further partial portions.

11. A tread according to any of the preceding claims, wherein a portion (7) forming said suction pad means (3) comprises several groups of partial portions (12), said groups of partial portions being aligned in different ways and/or having different shapes.

12. A tyre or similar means, ch a racte ri zed in that said tyre (1) or similar means is provided with a tread according to any one of claims 1 to 11.

13. A tyre according to claim 12, wherein only a portion of the width of said tyre (1) or similar means is provided with said suction pad means (3).

14. A tyre according to claim 13, wherein said portion provided with suction pad means (3) extends around the periphery of said tyre (1) and forms a suitable tread patterns or stripes around said periphery.