VEHICLE TIRES AND METHOD FOR PRODUCING AN EXTENDED APEX

Description

[0001] The invention relates to a vehicle tire comprising a carcass with a carcass ply, a bead core and a bead core rider radially above the bead core on it, wherein the carcass ply is folded around the bead core and the bead core rider.

[0002] It is common practice to incorporate a bead core and a bead core rib in a vehicle tire, as described above, and to embed them in a carcass ply. The bead core, also known as the apex or bead profile, serves to secure the tire firmly to the rim. In a cross-sectional plane defined by the axial and radial directions, the bead core rib typically has a triangular shape, with a base adapted to the axial width of the bead core and two radially tapered legs. Functionally, bead core ribs play a role in ensuring driving stability, precise steering response, and suspension comfort. The radial dimensions of the bead core rib can vary depending on the tire size, tire type, and desired characteristics.

[0003] According to the prior art, attempts have been made to advantageously influence the properties of a tire by additional structural features in the area of ​​the bead core. For example, JP 5280832 D2 provides, in addition to the bead core, a strip-shaped apex that extends axially within the bead core through the sidewall of the tire, between the axially inner and outer sections of the carcass ply. This is intended to ensure a good balance between steering stability and ride comfort, particularly in tires with thin sidewalls. EP3581403 A1 describes a bead reinforcement device comprising a bead stiffener and a rubber layer, wherein the rubber layer is configured to cover a surface of the bead that is not covered by the bead stiffener. CN110281705 A relates to a steel carcass tire, wherein a sticky layer is arranged between the carcass and a bead core.KR20100044660 A describes a tire with bead reinforcement, which is intended, among other things, to improve the tire's durability and performance. EP3135506 A1 describes a tire with a bead core and a bead core rider, wherein the core rider comprises a reinforcement section arranged between a main body of the core rider and a carcass in the axial direction of the tire and extending along the main body.

[0004] One problem in the manufacture of vehicle tires can arise when the tip of a bead core is positioned at an unfavorable location relative to the tire drum during the winding of the carcass ply. This can occur as follows: An axially central portion of the carcass ply is typically wound onto the tire drum at a first radial height. Towards the outer axis, the carcass ply may transition to a second radial height, which is lower than the first; this transition may occur along a curved section of the tire drum. Within the axial region of the second radial height, the bead core is positioned relative to the carcass ply in a mounting position, with the mounting position situated at a level between the first and second radial heights.Depending on the radial height of the bead core, the bead core rider, which sits on the bead core, can have its tip significantly below the first radial height or exhibit a greater relative extent. In the described arrangement, the tip of the bead core rider is positioned unfavorably if it rests on the carcass ply at a point of strong curvature and / or slope between the first and second heights, particularly near the first height. In this case, blistering can occur at the tip of the bead core rider when the carcass ply folds over the bead core and the bead core rider.

[0005] Another problem when fitting vehicle tires with bead seat inserts can be that a specific bead seat insert height is desired, which is not included in a standard range of bead seat inserts.

[0006] The invention is based on the objective of achieving the function of a stable bead core rider of flexible length in a vehicle tire using simple structural means.

[0007] The object stated is solved according to the invention by the features of the independent claims, namely, among other things, by a first strip of material between the carcass layer and the bead core rider bearing against an axially inner flank of the bead core rider, wherein a second strip of material between the carcass layer and the bead core rider bearing against an axially outer flank of the bead core rider, wherein the two strips of material rest on each other radially above the bead core rider.

[0008] By enclosing the bead core rider from opposite axial sides with a first and a second strip of material, the bead core rider is uniformly stabilized. Because the material strips rest radially on top of each other above the bead core rider, a strong bond with corresponding stability is achieved. This creates a stable radial extension of the bead core rider.

[0009] When the terms axial, radial, and circumferential are used in relation to a vehicle tire, they refer to the tire as intended when mounted on a vehicle and its rolling motion. In this context, the radial direction refers to a direction perpendicular to and intersecting the tire's axis of rotation. Radially inward refers to the orientation facing radially toward the axis of rotation. Radially outward refers to the orientation facing radially away from the axis of rotation. The circumferential direction describes the direction of rolling motion around the axis of rotation.When the vehicle is traveling forward, a circumferentially forward position on the tire reaches its minimum distance to the road surface earlier during a 360° rotation of the tire than a circumferentially rearward position, with the rearward position reaching its minimum distance to the road surface less than 180° behind the forward position. The axial direction refers to a direction parallel to the axis of rotation. "Axially inward" refers to an orientation that is axially aligned with a tire equator plane or equator line. The tire equator plane is a plane perpendicular to the tire's axis of rotation, passing through the center of the tire's axial width, with the tire equator line lying within the tire equator plane and on the tire's surface.A transverse direction is defined as a direction that consists of components of the radial direction and / or the axial direction.

[0010] The effects achieved with the features of the main claim are supported and further enhanced by preferred embodiments and configurations.

[0011] In a preferred embodiment, the bead core rider tapers to a point on a side facing away from the bead core when viewed in a section plane perpendicular to the circumferential direction. In this way, the two material strips can be applied radially above the bead core rider directly on top of each other without kinks or cavities.

[0012] The bead core and the bead core rider can extend together radially over a height of between 10 mm and 25 mm. From this height, it can be extended to a total length of, for example, 30 mm using the method according to the invention. The problem described at the outset, according to which the tip of a bead core rider can be located in an unfavorable position relative to the tire building drum, can occur particularly with bead core riders that, without the extension according to the invention, extend over 30 mm together with the bead core. In this respect, it can be advantageous to start with a smaller bead core rider and extend it according to the invention to a dimension that would actually be problematic under conventional manufacturing methods.

[0013] Alternatively, the bead core and the bead core rider can extend together in the radial direction over a height of more than 25 mm. An advantage can also be gained here, for example by extending a bead core rider from a standard range to an unusual dimension in the manner according to the invention.

[0014] The carcass ply is folded around the bead core and bead core rider such that an axially outer section of the carcass ply terminates radially above a radially lower end of the bead core rider. Alternatively, the carcass ply can be folded around the bead core and bead core rider such that an axially outer section of the carcass ply terminates radially below a radially upper end of one of the material strips, or radially below the radially upper ends of both material strips. Preferably, the carcass ply is folded around the bead core and bead core rider such that an axially outer section of the carcass ply rests radially above the bead core rider on an axially inner section of the carcass ply. Embedding the bead core, bead core rider, and material strips within the carcass provides the structure with additional stability.This is another difference compared to JP 5280832 D2, according to which the strip-shaped apex ends radially above the folded-over axial outer section of the carcass ply.

[0015] Alternatively, the carcass ply can be folded around the bead core and bead core rider in such a way that an axially outer section of the carcass ply does not rest radially above the bead core rider on an axially inner section of the carcass ply. In this case, another carcass ply can be placed axially outside over the axially outer section of the carcass ply and an exposed section of the material strips, which can also improve the embedding of the bead core, bead core rider, and material strips.

[0016] The axially outer section of the carcass ply can rest on the axially inner section of the carcass ply from a radial distance of 1.1 xe to 3 xe above the radial underside of the bead core rider, where e corresponds to the radial height of the bead core rider. In other words, the material strips, or at least one of the material strips, can extend up to the aforementioned distance above the radial underside of the bead core rider, so that the axially outer and inner sections of the carcass ply remain radially separated below the aforementioned distance by the material strip(s). The factor to be multiplied by e can be considered a direct expression of an extension factor of the bead core rider in the radial direction.The aforementioned range of values ​​is particularly advantageous here: If the factor exceeds 3, the ratio between the radial length and axial thickness of the extended bead core rider can become too large for a stable configuration. Below a value of 1.1, the overlap of the two material strips above the tip of the bead core rider can become too small for good cohesion. Even if the carcass ply is not folded around the bead core and the bead core rider in such a way that an axially outer section of the carcass ply rests radially above the bead core rider on an axially inner section of the carcass ply, the described extension factor can be an advantageous measure for the length of the material strips, such that the material strips extend to between 1.1 xe and 3 xe above the radial underside of the bead core rider.

[0017] The first material strip can project radially further outwards than the second material strip, or vice versa. In this case, the material strip projecting less radially outwards preferably terminates at least 1.1 xe and the material strip projecting further outwards at most 3 xe above the radial underside of the bead core rider. In any case, it is advantageous if the material strips do not terminate at the same radial height. Such a radial offset creates a staggered thickness in the section plane perpendicular to the circumferential direction, which can mimic the triangular shape of the bead core rider.In other words, the two material strips can lie on top of each other immediately above the tip of the bead core rider with an axial thickness of two material strips and extend together over a radial section of the bead core rider thus extended, with one of the material strips ending radially higher up, so that only the other material strip extends with a thickness of one material strip to the tip of the extended bead core rider.

[0018] Preferably, the first and / or second material strips do not radially overlap with the bead core. This keeps the arrangement slim at the radial height of the bead core. The first and / or second material strip(s) can be attached to the bead core rider directly radially above the bead core, resulting in maximum overlap with the flank(s) of the bead core rider. This enables a particularly stable construction. Furthermore, steps on the flanks of the bead core rider caused by the radially lower ends of the material strips can be avoided if these radially lower ends are positioned at the radially lower end of the bead core rider.

[0019] The first and / or second material strips can each have a thickness of 0.2 mm to 2 mm, preferably 0.5 mm to 1 mm. When installed in the vehicle tire, the thickness would extend primarily in the axial direction. With these values, a good compromise can be found between flexibility and a slim design on the one hand, and stability on the other.

[0020] The thickness of the first material strip can taper radially upwards, and / or the thickness of the second material strip can taper radially upwards. The thickness can even decrease to zero, so that the material strips have a triangular profile at their ends or along their entire radial length. This allows for a better approximation of the triangular shape of the bead seat in the extension of the material strips, and steps in the tire contour can be further minimized. In one embodiment, the material strips can, for example, end radially offset, and both taper in thickness towards their radially upward ends.In this way, for example, the full thickness of both material strips can be present radially directly above the tip of the bead core rider, whereby the thickness of the composite of the two material strips can decrease continuously over the end of a material strip ending radially lower to the thickness of one material strip and can decrease continuously to zero with the end of the material strip ending radially higher.

[0021] According to the invention, the material strips and the bead core rider comprise rubber compounds. The rubber compounds can differ from one another and be tailored to the specific requirements of the various components. According to the invention, the Shore hardness D of the material strips on the one hand and the bead core rider on the other hand is in a ratio of 1.0 to 5.4 to each other. This ensures sufficient stiffness of the extended bead core rider.

[0022] The invention further relates to a method for manufacturing a vehicle tire, wherein a first strip of material is placed on an axially inner section and a second strip of material is placed on an axially outer section of a carcass ply in a transverse direction to two sides of the target position of a bead core, wherein the bead core and a bead core rider are placed in an assembly position relative to the carcass ply, wherein the carcass ply is folded around the bead core and the bead core rider such that the first strip of material rests on an axially inner flank and the second strip of material rests on an axially outer flank of the bead core rider and that the second strip of material rests radially above the bead core rider on the first strip of material.

[0023] Preferably, the carcass ply is folded around the bead core and the bead core rider in such a way that the axially outer section of the carcass ply rests radially above the material strips on the axially inner section of the carcass ply.

[0024] The material strips can be placed on the carcass ply in a flat configuration while the carcass ply is, for example, lying on a conveyor belt. Alternatively, the material strips can be placed on the carcass ply in a cylindrical configuration when the carcass ply is wound on a tire-building drum, for example. The target position of the bead core lies in the axial or radial section of the carcass ply that directly surrounds the bead core after the carcass ply is folded over.

[0025] The mounting position of the bead core and bead core rider is the relative position into which the bead core and bead core rider are brought for the casing folding. The mounting position is achieved through a relative movement, i.e., by movements of the bead core and bead core rider and / or the casing ply. For example, the casing ply can be wound onto a tire-building drum, whereupon an axially outer section of the casing ply can be lowered radially so that the bead core can be brought into the mounting position above the lowered section and laterally to an axially central section of the casing ply. Once the bead core and bead core rider are in the mounting position, the casing ply can be folded over them from one or both axial sides of the bead core and bead core rider using suitable means, such as inflation mechanisms and / or robotic arms.

[0026] The method can be further developed with additional features, which are described in connection with the vehicle tire according to the invention. The vehicle tire can be further developed with additional features, which are described in connection with the method according to the invention.

[0027] Vehicle tires designed according to the invention are tires of any design, in particular radial tires, and tires of any type, in particular pneumatic tires for motor vehicles, such as passenger cars, light trucks or commercial vehicles.

[0028] The invention is described below by way of example with reference to the accompanying drawings and advantageous embodiments. The drawings show: Figure 1 schematic and partial sectional view of an embodiment of a vehicle tire according to the invention, Figure 2schematic and partial perspective view of a tire manufacturing drum with carcass layer and material strips, Figure 3 schematic and partial sectional view of tire components during an embodiment of the inventive method, Figure 4 Schematic and partial sectional view of tire components during a further embodiment of the method according to the invention.

[0029] Figure 1Figure 1 shows an embodiment of the vehicle tire 1 according to the invention in a section plane perpendicular to the circumferential direction, partially visible between a bead region and a shoulder region. The vehicle tire 1 is constructed in a manner known per se from components known per se, of which components important for understanding the present invention are marked with reference symbols. A carcass ply 2 is wrapped around a bead core 3 from an axially inner section 2b to an axially outer section 2a. A bead core rider 4, triangular in profile, sits on the bead core 3. The bead core 3 and the bead core rider 4 extend together radially over a height h. The bead core rider 4 extends on its own over a height e.

[0030] A first and a second material strip 5, 6 are located on the axially inner and outer legs of the bead core rider 4, respectively. Both material strips 5, 6 lie with their radially lower ends close to the radially lower end of the bead core rider 4 and above the radially upper end of the bead core 3. The first material strip 5 projects radially further beyond the upper tip of the bead core rider 4 than the second material strip 6. Between the tip of the bead core rider 4 and the radially upper end of the second material strip 6, the two material strips 5, 6 overlap. Due to the radially offset ends of the material strips 5, 6, an approximate triangular shape is formed radially above the bead core rider 4, which replicates the triangular shape of the bead core rider 4 and extends radially above it.Radially above the material strips 5, 6, the sections 2a, 2b of the carcass layer 2 lie on top of each other; in the embodiment shown, the folded-over, axially outer section 2a extends up to below the belt of the vehicle tire 1, so that the end of the axially outer section is in . Figure 1 is not visible.

[0031] Figure 2 Figure 7 shows a tire manufacturing drum 7 onto which a carcass layer 2 is wound. The tire manufacturing drum 7 is only partially shown, so only a portion of the carcass layer 2 is visible. In The illustration includes the axial position of a target position 3a of the bead core 3. InIn this area, the carcass ply 2 can be folded around a bead core 3 in a subsequent step. A first and a second material strip 5, 6 are placed on the carcass ply 2 axially to both sides of the target position 3a. The carcass ply 2 and the material strips 5, 6 extend over the entire circumference of the tire building drum 7 and the subsequent vehicle tire 1.

[0032] Figure 3 Figure 1 shows an intermediate position of the carcass layer 2 with the material strips 5, 6 and the bead core 3 with the bead core rider 4 during the turning over of the carcass layer 2 according to an embodiment of the manufacturing process according to the invention. As for Figure 1A sectional view was chosen in a section plane perpendicular to the circumferential direction. The illustration is merely a schematic basic pattern of the relative positions of carcass ply 2 and bead core 3 as well as bead core rider 4 and serves to demonstrate a basic sequence of movements; aids required for tire construction, such as a tire-building drum 7 and other tools, are shown in Figure 3 Not shown for clarity. In the illustrated embodiment, the bead core 3 is located in the target position 3a on the carcass layer 2, while an axially inner section 2b and an axially outer section 2a of the carcass layer 2a are folded axially towards each other around the bead core 3 and the bead core rider 4 (see arrows in Figure 3 ).

[0033] Figure 4Figure 1 shows an intermediate position of the carcass layer 2 with the material strips 5, 6 and the bead core 3 with the bead core rider 4 during the turning over of the carcass layer 2 according to an alternative embodiment of the manufacturing process according to the invention. As for Figure 1 and Figure 3 A sectional view was chosen in a section plane perpendicular to the circumferential direction. How to Figure 3 described, serves Figure 4 This merely serves to illustrate a schematic basic pattern of the relative positions and to demonstrate a basic sequence of movements. The axially inner section 2b of carcass layer 2 is according to Figure 4 at a higher radial level than the axially outer section 2a. Such a change in height can be achieved on a tire construction drum 7 located radially inside the carcass layer 2, which is in Figure 4not shown. The transition occurs with a certain curvature, which may also be determined by the tire building drum. Thanks to the illustrated change in height, the bead core 3 and bead core rider 4 can be brought axially from the side radially over the axially outer section 2a of the carcass ply 2.

[0034] The bead core 3 and the bead core rider 4 are located according to Figure 4 already in an assembly position of the illustrated embodiment, wherein the bead core 3 is already laterally in its target position 3a against the carcass layer 2. The axially outer section 2a is, as indicated by the arrow in Figure 4 indicated, folded around the bead core 3 and the bead core rider 4. This can be done, for example, by means of an inflation mechanism.

[0035] As a final result, a manufacturing process according to both embodiments can be used to produce the Figure 3 and 4 a vehicle tire in the Figure 1The configuration shown is created. Reference symbol list

[0036] 1 Vehicle tire 2 Carcass ply 2a Axial outer section (of the carcass ply) 2b Axial inner section (of the carcass ply) 3 Bead core 3a Target position of the bead core 4 Bead core rider 5 First material strip 6 Second material strip 7 Tire building drum

Claims

1. Vehicle tyre (1) comprising a carcass with a carcass ply (2), a bead core (3) and a bead filler (4) which is seated on the bead core (3) radially above the latter, wherein the carcass ply (2) is wrapped around the bead core (3) and the bead filler (4), wherein a first material strip (5) between the carcass ply (2) and the bead filler (4) bears against an axially inner flank of the bead filler (4), wherein a second material strip (6) between the carcass ply (2) and the bead filler (4) bears against an axially outer flank of the bead filler (4), wherein the two material strips (5, 6) bear on one another radially above the bead filler (4), characterized in that the material strips (5, 6) and the bead filler (4) comprise rubber mixtures, wherein the Shore hardness D of the material strips (5, 6) and the Shore hardness D of the bead filler (4) are in a ratio of 1.0-5.4 in relation to one another.

2. Vehicle tyre (1) according to Claim 1, characterized in that, when viewed in a section plane perpendicular to the circumferential direction, the bead filler (4) tapers to a point on a side relatively remote from the bead core (3).

3. Vehicle tyre (1) according to either of Claims 1 and 2, characterized in that the bead core (3) and the bead filler (4) together extend over a height (h) of between 10 mm and 25 mm in the radial direction.

4. Vehicle tyre (1) according to one of Claims 1 to 3, characterized in that the carcass ply is wrapped around the bead core (3) and the bead filler (4) in such a way that, radially above the bead filler (4), an axially outer portion (2a) bears from axially at the outside on an axially inner portion (2b) of the carcass ply (2).

5. Vehicle tyre (1) according to Claim 4, characterized in that, from a radial distance of 1.1 x e to 3 x e above the radial bottom side of the bead filler (4), the axially outer portion (2a) of the carcass ply (2) bears from axial at the outside on the axially inner portion (2b), where e corresponds to the radial height of the bead filler (4).

6. Vehicle tyre (1) according to one of Claims 1 to 5, characterized in that the first material strip (5) projects radially further outwards than the second material strip (6), or in that the second material strip (6) projects radially further outwards than the first material strip (5).

7. Vehicle tyre (1) according to one of Claims 1 to 6, characterized in that the first material strip (5) does not radially overlap the bead core (3), and / or in that the second material strip (6) does not radially overlap the bead core (3).

8. Vehicle tyre (1) according to one of Claims 1 to 7, characterized in that the first material strip (5) has a thickness of 0.2 mm to 2 mm, preferably a thickness of 0.5 mm to 1 mm, and / or in that the second material strip (6) has a thickness of 0.2 mm to 2 mm, preferably a thickness of 0.5 mm to 1 mm.

9. Vehicle tyre (1) according to one of Claims 1 to 8, characterized in that the thickness of the first material strip (5) tapers radially upwards, and / or in that the thickness of the second material strip (6) tapers radially upwards.

10. Method for producing a vehicle tyre (1), wherein, in a transverse direction on two sides of a target position (3a) of a bead core (3), a first material strip (5) is placed on an axially inner portion (2b), and a second material strip (6) is placed on an axially outer portion (2a), of a carcass ply (2), wherein the target position (3a) of the bead core (3) lies in that axial or radial portion of the carcass ply (2) by which the bead core (3) is directly surrounded after the turn-up of the carcass ply (2), wherein the bead core (3) and a bead filler (4) are placed in a fitting position relative to the carcass ply (2), wherein the carcass ply (2) is wrapped around the bead core (3) and the bead filler (4) in such a way that the first material strip (5) bears against an axially inner flank, and the second material strip (6) bears against an axially outer flank, of the bead filler (4), and in that the second material strip (6) bears on the first material strip (5) radially above the bead filler (4), characterized in that the material strips (5, 6) and the bead filler (4) comprise rubber mixtures, wherein the Shore hardness D of the material strips (5, 6) and the Shore hardness D of the bead filler (4) are in a ratio of 1.0-5.4 in relation to one another.

11. Method according to Claim 10, wherein the carcass ply (2) is wrapped around the bead core (3) and the bead filler (4) in such a way that the axially outer portion (2a) of the carcass ply (2) bears on the axially inner portion (2b) of the carcass ply (2) radially above the material strips (5, 6).