Vehicle tyre

Abstract: A pneumatic vehicle tyre with a radial carcass and a breaker reinforcement layer comprising a plurality of bandage strips (4) which each extend in the peripheral direction of the tyre and which are differently overlapped when considered over the width of the breaker. The strips (4) are preferably formed by a continuous winding of a single strip and may be combined with a conventional breaker ply.

Description: This invention relates to a vehicle tyre comprising a radial carcass and tread reinforcing breaker or belt arranged between the carcass and tread. Vehicle tyres of this kind are generally known, and it is also known to influence the characteristics of particular vehicle tyres by the layout of the breaker plies and components used and also by the choice of materials for such breaker components. A pneumatic tyre comprising a carcass and breaker reinforcement arranged between the carcass and tread region wherein a least one layer of the breaker reinforcement comprises a plurality of at least partially overlapping bandage strips extending in the peripheral direction of the tyre is known, e.g. from Patent Publication US-A-3991803. It is an object of the invention to construct a vehicle tyre of the above kind in such a way that the tyre characteristics can be intentionally influenced to a high degree, in particular also in dependence on the respective layout of the profile over the width of the tyre. According to the present invention a vehicle tyre comprises a carcass and a breaker reinforcement arranged between the carcass and a tread region, at least one layer of the breaker reinforcement comprising a plurality of at least partially overlapping bandage strips extending in the peripheral direction of the tyre characterised in that the carcass is a radial carcass and the width of overlap between adjacent bandage strips is greater in a region of lower tread profile stiffness than in a region of higher tread profile stiffness. By this construction it is possible, due to the choice of the width of overlap between adjacently disposed strips, to predetermine the stiffness of the breaker in a defined manner for the individual regions of the total width of the breaker, and in particular to adapt the stiffness of the breaker to any variation in the tread stiffness resulting from the layout of the profile of the tread. The width of overlap between bandage strips is selected in the region of lower tread profile stiffness, i.e. in the region of the circumferential grooves, to be greater than in the region of higher tread profile stiffness. Furthermore, whilst the overlap varies at least in part of the width of the breaker layer other parts may have an overlap and an edge to edge arrangement of the strips. Thus great freedom can be taken in the design of the tread profile, since weak regions resulting from the tread profile layout for example by the use of large grooves, can be fully compensated for by a correspondingly large overlap of the bandage strips in these regions. It is possible also to achieve an advantageous reinforcement of a side of the tyre particularly loaded by camber when run on a vehicle, in that the width of overlap between the bandage strips can be selected to be greater in the region of the side loaded by the camber than it is at the opposite side where the load is less. By presetting specific widths of overlap the dynamic contour of the particular tyre can also be advantageously influenced and it can be assured that undesired increases in diameter due to high rotational tyre speeds are effectively prevented. Whilst this is provided by selecting the widths of overlap of the bandage strips this may be further assisted by using for the bandage strips in some regions a reinforcement material which has a higher restraining effect against the rotation caused and undesired increases in tyre diameter. For example aramid, available as Kevlar (Registered Trade Mark), may be used as the reinforcement in the strip material in those regions in which a particularly pronounced restraining effect is desired. Furthermore it is also possible to arrange layers of wound bandage strips above one another, such that the overlapping regions are formed which lie above one another in the radial direction of the tyre. Such a design provides a strip wound C-fold type construction where the strips overlap to differing amounts. Both edges may be C-folded or in the case of a tyre specially for a vehicle running with camber one wall of the tyre may have a C-fold edge to a breaker ply. In both cases a further breaker layer, in particular for example a steel layer,can be provided within the C-fold layer. Some embodiments of the invention will now be described, by way of example only, in conjunction with the attached diagrammatic drawings in which:- Figure 1 is a schematic cross section of a tread and breaker according to the invention; Figure 1(a) is an enlarged details of Fig. 1; Figure 1(b) is a graph of strip overlap for Figure 1; Figures 2 & 3 are a second and third variant cross sections; Figure 4 is a cross section of an embodiment with a special camber-loaded side of the tyre; Figure 5 is a schematic illustration of bandage windings which are subdivided over the width of the tyre. The tyre of Figure 1 has a radial carcass 1, a tread region 2 and a breaker layer 3 arranged therebetween. The breaker layer 3 comprises a plurality of bandage strips 4 which each extend in the peripheral or circumferential direction of the tyre and which are wound so as to be mutually overlapping as shown. The width of each bandage strip is generally between 5mm and 20mm and the strips comprise parallel reinforcement cord materials such as polyester or nylon. The number of cords per strip can be for example 5 to 15 cords laid adjacent to one another and embedded in a topping material conventional in the art. Figure 1(a) shows the relationship between two adjacent breaker strips 4 of the breaker. As can be seen the amount of overlap x is approximately half the width of the strips. This overlap x can be varied by adjusting the position wound for each strip and thus the amount of reinforcement material i.e. the number of cords, can be varied across the width of the breaker as required. It is an important feature of the invention that variations of reinforcement and thus variations of the stiffness of the tyre in the tread zone between the sidewalls can be varied as desired. The manner in which the profile stiffness of the tyre between the sidewalls - which changes due to the profile construction or layout - can be influenced by the breaker layer formed in accordance with the invention is made clear in the diagrammatic representation of Figure 1(b). The tread 2 of the tyre in Figure 1 has two pronounced peripheral grooves provided in the tread surface and so the profile stiffness of the tread region is greatly reduced in this region. In order to compensate for this the bandage strips 4 are wound in the regions of the peripheral grooves with a substantially greater overlap x than in the rest of the breaker layer width. The stiffness characteristic is thus intentionally predetermined to a high degree by this pronounced increase of the overlap. Indeed this allows variation of overlap from zero to complete overlap i.e. O≦X≦ strip width and ready control of each part of the breaker width with respect to the reinforcement and thus in addition to other properties its stiffness and the resultant tread/breaker stiffness between the sidewalls. In the first variant of Figure 2 a comparatively low overlap x is used in the shoulder regions of the tyre, whereas a greater overlap y is used in the regions of the pronounced peripheral grooves. This provides different reinforcements in the different regions as set out above. When desired, as a result of the desired stiffness conditions, in particular having regard to a particular bead stiffness dynamic contour, regions without overlap of the bandage strips 4 can also be provided, considered across the width of the tyre, as is for example illustrated in the region x in the third variant of Figure 3. In addition to the wound breaker layer in accordance with the invention one or more conventional breaker layers of cut edge or non-cut edge types can be used to make up the total breaker assembly. In Figure 4 an embodiment of the invention is shown providing an increased strength and stiffness at the camber loaded side of a tyre. For this purpose a C-fold breaker construction is formed by winding the bandage strips 4, applying a further cut-edge breaker layer 5, which preferably consists of steel cords and then continuing winding of the strip to form an overlapping region i.e. a C-fold layer. In this case only one side is C-fold to suit the high camber edge of the tyre. Similar construction with C-fold at both sides are of course possible though not shown here or explained in detail. The reinforcement cords for the bandage strips can be any of the materials known in the art for breaker reinforcement cords including steel, aramid, or nylon. Indeed the breaker layer of the invention does not have to be wound throughout of the same material. It is for example possible to wind bandage strips of a first material, for example aramid, in the shoulder regions and to wind the middle region of bandage strips of a second material, for example nylon. In this way the different extension characteristics of the different materials can be ideally combined, and the desired restraining characteristics of these materials can be exploited at high speeds of rotation. Joins in the winding can be by various means including overlapped joints. Figure 5 shows such a construction schematically.

Claims: A vehicle tyre comprising a carcass (1) and a breaker reinforcement (3) arranged between the carcass and a tread region (2), at least one layer of the breaker reinforcement (3) comprising a plurality of at least partially overlapping bandage strips (4) extending in the peripheral direction of the tyre characterised in that the carcass (1) is a radial carcass and the width of overlap (x) between adjacent bandage strips (4) is greater in a region of lower tread profile stiffness than in a region of higher tread profile stiffness. A vehicle tyre in accordance with claim 1 characterised in that the width of overlap (x) between the bandage strips (4) on the side of the tyre loaded by camber is greater than at the opposite side. A vehicle tyre in accordance with claims 1 or 2 characterised in that the bandage strips (4) lie alongside one another with zero overlap under a region of high tread profile stiffness and in a region of low profile stiffness substantial overlap (x) occurs. A vehicle tyre in accordance with claims 1 or 2 characterised in that the bandage strips (4) lie alongside one another free of overlap (x) over a width (z) in a central region of the tyre. A vehicle tyre in accordance with any of the preceding claims characterised in that several bandage strips (4) are arranged mutually displaced above one another in regions of greater overlap. A vehicle tyre in accordance with any of the preceding claims characterised in that at least two layers of mutually displaced overlapping bandage strips (4) are provided above one another in one shoulder region. A vehicle tyre in accordance with any of the preceding claims characterised in that at least two layers of mutually displaced overlapping bandage strips (4) are provided above one another in both shoulder regions. A vehicle tyre in accordance with any of the preceding claims characterised in that an additional breaker ply (5) comprising reinforcement cords is provided between the carcass ply (1) and the bandage strips (4). A vehicle tyre in accordance with any of claims 1 to 8 characterised by one or more breaker plies (5) and the bandage strips (4) are beneath said plies (5) and wrap outwardly around one of the edges so that the wound strips (4) provide a C-folded ply edge construction. A vehicle tyre in accordance with any of claims 1 to 8 characterised by one or more breaker plies (5) and the bandage strips (4) are beneath said plies (5) and wrap outwardly around both of the edges so that the wound strips (4) provide a C-folded ply edge construction. A vehicle tyre in accordance with any of claims 1 to 10 characterised in that overlapped bandage strips (4) of a first material are provided in one region of the width of the tyre, and in that bandage strips (4) of a second material are provided in a second region of the tyre width. A vehicle tyre in accordance with claim 11 characterised in that overlapped bandage strips (4) of a material of low elongation are provided in the region of both tyre shoulders and in that bandage strips (4) of a material with a comparatively larger elongation are provided in the middle region. A vehicle tyre in accordance with claim 11 or 12 characterised in that the bandage strip regions of different material mutually overlap to a predetermined degree. A vehicle tyre in accordance with any of the preceding claims characterised in that the bandage strips (4) in the shoulder region consist of aramid and the bandage strips (4) in the middle region consist of nylon. A vehicle tyre in accordance with any of the preceding claims characterised in that the bandage strips (4) are continuously wound over the entire width of the tyre.

Inventors: SPONAGEL PETER, SPONAGEL, PETER
Applicants: SP REIFENWERKE GMBH
Application year: 1990
Main classification: B60C9
IPC codes: B60C9, B60C11