Conductivity channel for a vehicle tire and manufacturing process

Abstract

Vehicle tire (1) comprising a carcass (2) with an inner layer (2a), a belt assembly (3) with at least one first belt layer (3a), a belt bandage (4) and a tread (5) with a running surface (6), wherein a first conductivity channel (7) extends between a radially outer end (7a) on the running surface (6) and a radially inner end (7b), wherein the first conductivity channel (7) extends in the axial direction over less than 10% of an axial width of the vehicle tire (1) and in the circumferential direction over less than 30°, The radial inner end (7b) of the first conductivity channel (7) is arranged between a radial position located inside the tread (5) and a radial outer side of the inner layer (2a).

Description

[0001] The invention relates to a vehicle tire comprising a carcass with an inner layer, a belt assembly with at least a first belt ply, a belt bandage and a tread with a tread, wherein a first conductivity channel extends between a radially outer end on the tread and a radially inner end, wherein the first conductivity channel extends in the axial direction over less than 10% of an axial width of the vehicle tire and in the circumferential direction over less than 30°.

[0002] As rubber compounds with higher silica and lower carbon black content are increasingly used in vehicle tires to reduce rolling resistance, additional measures must increasingly be taken to ensure a sufficiently low electrical resistance between the tread and the rim to dissipate static charges. In this context, it is generally known to provide conductivity channels between a tread and a radially lower position in a vehicle tire.A particularly common solution for this is a so-called carbon center beam, which extends in a ring around the entire circumference of the vehicle tire and usually has a radial extension between the tread and the radial upper side of a belt bandage. The carbon center beam electrically bridges a tread optimized for rolling resistance and, compared to the carbon center beam, has lower conductivity. In appropriately equipped vehicle tires, the belt bandage is usually electrically conductive and is connected to a bead region of the vehicle tire by additional electrically conductive components, so that the carbon center beam is designed as part of an electrically conductive path extending from the road surface to the rim.

[0003] There are approaches to modifying the generic shape of a carbon center beam described above.EP 3 727 897 B1 describes a tire with a substantially insulating crown block and a substantially insulating tread, the tire further comprising at least one conductive pin oriented in the radial direction and positioned beneath the tread of the tire, the at least one pin cooperating with a conductive inner element of the tire, the at least one conductive pin being arranged in a recess flush with the inner surface of the cavity of the tire, the at least one conductive pin having a pin head formed in the extension of a pin shank and arranged beneath the tread of the tire, outside the recess, and the pin head having a diameter at least greater than 1.5 times the diameter of the shank of the at least one pin.The pin is an element which, once installed in the tyre, extends over a very short section in relation to the circumference of the tyre and over a very narrow section compared to the width of the tread.

[0004] The invention is based on the object of creating a solution for an electrical bridge between the tread and radially inner components of the vehicle tire, wherein the solution is to be even less invasive with respect to the basic structure of the vehicle tire compared to the prior art.

[0005] The stated object is achieved according to the invention in that the radially inner end of the first conductivity channel is arranged between a radial position located in the interior of the tread and a radial outer side of the inner layer.

[0006] The invention recognizes that a conductivity channel that is significantly shortened in the circumferential direction compared to a conventional carbon center beam can be sufficient to dissipate static charges, advantageously leaving more volume in the tire for rubber compounds optimized for rolling resistance. Furthermore, the invention recognizes that a conductivity channel with such a reduced cross-section can extend radially deeper into the vehicle tire than a conventional carbon center beam and, in contrast to the conventional carbon center beam, can, for example, also radially overcome a belt assembly and / or a belt bandage. On the other hand, the invention recognizes that a complete radial penetration of the vehicle tire, in particular a penetration of the inner layer, is not necessary to create a well-functioning electrical bridge.Because the conductivity channel never extends deeper than a radially outer side of the inner layer, the integrity of this sensitive component, which is essential for the airtightness of the vehicle tire, can be maintained. In particular, the invention recognizes that the radially inner end of the first conductivity strip can advantageously extend exactly to a radially outer side of the first electrically conductive layer in the vehicle tire, viewed from radially outside to radially inside.

[0007] Where the directional terms axial, axial direction, radial, radial direction, and circumferential direction are used, these refer to the vehicle tire as intended and its rolling motion. The radial direction refers to a direction perpendicular to the rotational axis of the vehicle tire and intersecting the rotational axis. Inward radial direction refers to the orientation that faces the rotational axis in the radial direction. Outward radial direction refers to the orientation that faces away from the rotational axis in the radial direction. The circumferential direction refers to the direction of rolling motion around the rotational axis.As the vehicle moves forward, a circumferentially forward position on the vehicle tire passes through a minimum distance from the road surface earlier than a circumferentially rearward position during a 360° rotation of the vehicle tire, with the circumferentially rearward position passing through its minimum distance from the road surface less than 180° behind the forward position. The axial direction refers to a direction parallel to the axis of rotation. Pointing axially inward refers to an orientation that faces a tire equator plane or a tire equator line. The tire equator plane is a plane perpendicular to the axis of rotation of the vehicle tire that runs through the center of the axial width of the vehicle tire, with the tire equator line running in the tire equator plane and on the surface of the vehicle tire.The transverse direction is a direction that consists of components of the radial direction and / or the axial direction.

[0008] In particular, the circumferential direction and the transverse direction can run on a base surface of the tread. The base surface coincides with the smooth surface that the tread would have if no small-scale profile elements, such as grooves or snow edges, were provided. Small-scale profile elements are characterized in at least one of the three dimensions: radial direction, axial direction, and circumferential direction, by a dimension and / or by a radius of curvature that is smaller than a maximum tread depth in the vehicle tire. Specifically, the base surface remains physically intact wherever no such profile elements are provided. The retained sections of the base surface can be at least partially intended for contact with a road surface.Where, for example, a groove runs through a tread of a vehicle tire, the base area continues as an imaginary surface above the groove; where, for example, a snow edge is located on the tread, the base area continues as an imaginary surface below the snow edge.

[0009] A conductivity channel is preferably characterized by a lower electrical resistance than any reference volume with the same cross-section perpendicular to the radial direction as the conductivity channel, wherein the reference volume is arranged away from conductivity channels, but at the same radial level and over the same radial extent in the vehicle tire. In one embodiment, the first conductivity channel can have a higher electrical conductivity along its entire radial extent at a given radial depth than the rest of the vehicle tire at this radial depth. Depending on requirements, a vehicle tire should have a leakage resistance of 1 × 10 6 Ω, 1 × 10 8 Ω or 1 × 10 10Ω. The conductivity of the conductivity channel and its dimensions can be adjusted depending on these limits and taking into account the resistance of any other components of the electrical path through the vehicle tire.

[0010] In addition to the desired electrical conductivity, the dimensions of a conductivity channel according to the invention can also be determined by other considerations. For example, the smaller the volume of the conductivity channel, the less the impact on rolling resistance will be if the conductivity channel is made of a material with higher rolling resistance than the vehicle tire in the vicinity of the conductivity channel. Furthermore, under suitable circumstances, a particularly narrow conductivity channel can be routed between the reinforcements running in reinforcement layers and thus radially, for example, through a belt bandage, a belt, and / or a textile cord insert of a carcass. The first conductivity channel preferably extends in the axial direction over less than 3% of an axial width of the vehicle tire and in the circumferential direction over less than 1°.A cross-sectional area of ​​the first conductivity channel determined perpendicular to the radial direction preferably measures between 0.1 mm. 2 and 20 mm 2 , preferably between 1 mm 2 and 2 mm 2 .

[0011] The radially inner end of a conductivity channel according to the invention can be arranged inside the tread. In particular, the tread can comprise a radially outer layer, also called a cap, and a radially inner layer, also called a base. The radially inner end of the conductivity channel can then be arranged on a radial outer side of the base. Such an arrangement is particularly useful when the base has sufficient conductivity to function as part of an electrically conductive path through the vehicle tire. The conductivity channel preferably extends radially to below the tread, so that the radially inner end of the first conductivity channel is preferably arranged between a radial outer side of the belt bandage and a radial outer side of the inner layer.According to a particularly preferred embodiment, the radially inner end of the first conductivity channel is located on a radial outer side of the first belt ply, wherein the first belt ply is the only or the radially lowest belt ply of the belt assembly. Such an arrangement is particularly useful when the lowest belt ply has sufficient conductivity to function as part of an electrically conductive path through the vehicle tire. The lowest belt ply is usually the axially widest belt ply of a belt assembly, from which electrical contact can accordingly be particularly easily established with components arranged radially further down and / or axially further outwards, such as the carcass or the sidewalls. In contrast, it is less easy to establish such electrical contact from a belt ply arranged radially further outwards past or through the first belt ply.

[0012] The first conductivity channel can be arranged in an area centered around a tire equator with a width of 10% of the vehicle tire's axial width. Near the tire equator, the probability of contact with a road surface during normal driving is higher than in an axial position closer to the tire shoulder, so that with an appropriate arrangement of the conductivity channel, the most reliable dissipation of static charge can be ensured.

[0013] Since static charge builds up primarily while a vehicle equipped with tires is moving, its dissipation is also primarily necessary while the vehicle is moving, i.e. when the vehicle tire is rotating. For this reason, it may be sufficient to arrange a single conductivity channel in the vehicle tire, even if this conductivity channel is not in contact with the road surface when the vehicle is stationary due to its limited extent in the circumferential direction, depending on the rotational position of the vehicle tire. Preferably, however, one or more further conductivity channels similar to the first conductivity channel are arranged in the vehicle tire. Conductivity channels that share essential features of the first conductivity channel but do not have to be identical to the first conductivity channel in every detail are considered to be similar to the first conductivity channel.For example, the radially inner end of the first conductivity channel can be arranged on a radial outer side of the first belt ply, whereas the radially inner end of a further conductivity channel can be arranged, for example, on a radial outer side of the belt bandage. Similarly, various further conductivity channels can differ from one another in details. In a preferred embodiment, between 2 and 20, more preferably between 5 and 15 conductivity channels are arranged in the vehicle tire. In a preferred embodiment, the first and the further conductivity channels are arranged distributed over the circumference of the vehicle tire such that, regardless of a rotational position of the vehicle tire, a radially outer end of a conductivity channel is always arranged within a ground contact area.The ground contact area corresponds to the statically determined footprint at a load of 70% of the maximum load capacity at an internal pressure of 85%, determined according to ETRTO standards.

[0014] According to one embodiment, at least one of the additional conductivity channels is arranged outside a region centered around a tire equator with a width of 10% of the axial width of the vehicle tire. In this way, contact with the road surface can be enabled, especially when the vehicle tire is tilted. Such an arrangement can be particularly advantageous in vehicle tires for single-track vehicles, especially for motorcycles, because such vehicles can assume a pronounced tilt, especially when cornering.

[0015] Vehicle tires designed according to the invention include tires of any design, in particular radial tires, and tires of any type, in particular pneumatic vehicle tires for motor vehicles, such as passenger cars, light trucks, or commercial vehicles. Vehicle tires for two-wheeled vehicles, in particular for single-track vehicles, are also encompassed by the invention.

[0016] The invention also relates to a method for producing a first conductivity channel according to the above and / or following description. In a first step of the method, a vehicle tire without a first conductivity channel and a syringe filled with a conductive substance are provided. In a second step, a cannula of the syringe is inserted into the vehicle tire from the position of a radially outer end of a first conductivity channel to be produced to the position of a radially inner end of the first conductivity channel to be produced. In a third step, the cannula is removed from the vehicle tire again, wherein the conductive substance is pressed from the syringe into the vehicle tire, such that the first conductivity channel is formed from the conductive substance in a vacancy left behind by the cannula.

[0017] The conductive substance should be designed so that it can be applied with a syringe. Furthermore, the conductive substance should be designed so that the resulting conductive channel has a sufficiently high electrical conductivity to contribute to compliance with relevant leakage resistance limits as part of the electrical path through the vehicle tire.

[0018] During the second step, the cannula can be guided through one or more radial sections of the vehicle tire between adjacent reinforcement members perpendicular to the radial direction, wherein the reinforcement members can run in reinforcement layers, such as those of a belt ply, a belt bandage, or a carcass. For this purpose, a suitable diameter of the cannula can be selected; in this way, the cannula can penetrate between two reinforcement members without touching them. Furthermore, a tip of the cannula can have a suitable shape; for example, a rounded tip can deflect the cannula if it encounters a reinforcement member during insertion and guide it through an adjacent gap.Furthermore, the cannula can have sufficient stability so that when the cannula encounters a strength support, it is able to easily displace it in order to create continuous space for the cannula between the radially outer and inner ends of the conduction channel to be produced.

[0019] The vehicle tire provided in the first step of the process can be a pre-vulcanized vehicle tire. In particular, the process can also be used to retrofit finished vehicle tires to improve their conductivity.

[0020] In an alternative embodiment of the method, the vehicle tire provided in the first step of the method is a green vehicle tire and can, in particular, contain a substantially unvulcanized rubber compound. This makes it particularly easy to insert the syringe's cannula. The conductive substance can be vulcanizable and not yet vulcanized up to and including the third step. In particular, the conductive substance can be an unvulcanized rubber compound with amounts of carbon black as a filler suitable for good conductivity. In a fourth step, the vehicle tire can be vulcanized together with the conductive substance pressed into the vehicle tire. Any deformations to the components of the vehicle tire caused by the insertion of the cannula and / or the conductive substance can be compensated for in a vulcanization mold.

[0021] The method can be further developed with additional features that are described in connection with the vehicle tire according to the invention. The vehicle tire can be further developed with additional features that are described in connection with the method according to the invention.

[0022] The invention is described below by way of example with reference to advantageous embodiments in the accompanying drawings. They show: Fig. 1 schematically and partially a sectional view of an embodiment of a vehicle tire according to the invention, Fig. 2 schematically shows a side view of another embodiment of a vehicle tire according to the invention, Fig. 3 schematically shows a snapshot according to an embodiment of the method according to the invention.

[0023] Fig. Figure 1 shows a partial sectional view of an embodiment of a vehicle tire 1 according to the invention. The sectional plane is spanned by the radial direction, shown in the vertical direction of the drawing plane, and the axial direction, shown in the transverse direction of the drawing plane. The section of the vehicle tire 1 shown extends from a tire equator plane 8 axially outward and from a radially outer apex of the vehicle tire 1 radially inward, but ends radially above a bead region of the vehicle tire 1 (not shown).

[0024] A carcass 2 runs radially and axially inward and consists of a radially inner inner layer 2a and a radially outer textile cord ply 2b. The textile cord ply 2b is electrically conductive to such an extent that the textile cord ply 2b can function as an effective part of an electrical path through the vehicle tire 1. A first belt ply 3a is arranged radially outside the textile cord ply 2b, wherein the first belt ply 3a, like the textile cord ply 2b, is designed to be conductive in order to contribute to an electrically conductive path through the vehicle tire 1. The radial outer side of the first belt ply 3a is contacted by the radially inner end 7b of a first conductivity channel 7. The radially outer end 7a of the first conductivity channel 7 is flush with a tread 6 on the tread 5 of the vehicle tire 1 and close to the tire equator plane 8 orarranged near the tire equator 8, so that the radially outer end 7a can come into contact with a road surface when the vehicle tire 1 is in a suitable rotational position. In this way, the prerequisites for an electrically conductive path between the road surface and a rim (not shown) are met, wherein the electrically conductive path leads through the first conductivity channel 7, further through the first belt ply 3a and through the textile cord insert 2b of the carcass 2, wherein a contact area with a rim can additionally be created in the bead area of ​​the vehicle tire 1 by suitable measures.

[0025] A sidewall 10 and a tread 5 are arranged radially or axially on the outside, whereby a separation at the transition between the two components is not shown for the sake of clarity. Any subdivision of the tread 5 into a radially outer cap and a radially inner base is also not shown for the sake of clarity. Radially below the tread 5 is a belt bandage 4, which can be wound, for example, as a wound bandage over the belt assembly 3. Radially below the belt bandage 4 is a second belt layer 3b, which completes the first belt layer 3a to form a belt assembly 3. Any details such as belt edge pads are shown in Fig. 1 not shown for the sake of clarity; the position of the belt bandage 4 above the belt layers 3a, 3b is also only shown in a simplified manner. Tread 5, belt bandage 4 and second belt layer 3b are not conductive or have a lower electrical conductivity than the first belt layer 3a and / or the textile cord ply 2b of the carcass 2. These gradations of conductivity relate in particular to the rubber compound used in a respective component and not to the reinforcements embedded therein; thus, it is particularly a question of the conductivity of a respective component as it can be determined between a radial outer side and a radial inner side of this component, wherein the radial outer and inner sides are covered with rubber compound.

[0026] The first conductivity channel 7 extends radially through the tread 5, the belt bandage 4 and the second belt layer 3b. In this way, an electrical bridge can be created between the road surface and a first conductive or comparatively more conductive radial layer of the vehicle tire 1, which bridges the non-conductive or comparatively less conductive components. In the case of the Fig. 1, the first conductive or comparatively more conductive layer of the vehicle tire 1, viewed from the radial outside, is the first belt layer 3a, wherein the non-conductive or comparatively less conductive components comprise the tread 5, the belt bandage 4 and the second belt layer 3b.

[0027] Fig. Figure 2 shows a further embodiment of a vehicle tire 1 according to the invention. The vehicle tire 1 is shown from the side, with the drawing plane spanned by the radial direction and the circumferential direction. The tread 5, the belt bandage 4, the belt assembly 3, and the carcass 2 extend between the tread 6 and a radial inner side 2a* of the inner layer 2a. A view of the radial inner side 2a* of the inner layer 2a would actually be hidden by the sidewall 10, but is not shown in Fig. 2 but still marked; the Fig. 2 is therefore to be understood more as a schematic illustration of the technical relationships than as a line drawing based on a photorealistic image. In addition to a first conductivity channel 7, further conductivity channels 9 are arranged in the vehicle tire 1. The conductivity channels 7, 9 extend radially between the tread 6 and a radial depth between a radial position located inside the tread 5 and a radial outer side of the inner layer 2a. The conductivity channels 7, 9 can be arranged axially near the tire equator 8, for example, like the first conductivity channel 7 according to Fig. 1. In this case, a view of the conductivity channels 7, 9 would actually be hidden by the tread 5, the belt bandage 4, the belt assembly 3 or the textile cord insert 2b; here again, reference is made to the schematic and technically illustrative nature of the Fig. 2.

[0028] Fig. 3 schematically shows a snapshot of an embodiment of the method according to the invention. It shows a sectional view of a section of a vehicle tire 1 in the region of the tread 5, the belt bandage 4 and the belt assembly 3, wherein the sectional plane is spanned by the radial direction and the axial direction. From radially bottom to radially top, a carcass 2, a belt assembly 3 comprising first and second belt plies 3a, 3b, a belt bandage 4 and a tread 5 are layered one above the other. The cannula 13 of a syringe 12 projects radially from a tread 6 to a position arranged within the tread 5. At a time before the time of the snapshot according to Fig. 3, the cannula 13 protruded radially down to the outside of the first belt ply 3a. From here, the cannula 13 was withdrawn from the vehicle tire again, while at the same time a conductive substance 11 was pressed out of the syringe. In this way, a radially lower part of a conductive channel 7 was formed in the radial and axial region into which the cannula 13 had previously penetrated. In the further course of the method, the cannula 13 will be completely removed from the vehicle tire 1, while at the same time further conductive substance 11 will be pressed out of the syringe 12, so that finally a complete conductive channel 7 will extend radially between the radial outside of the first belt ply 3a and the tread 6.

[0029] In the first and second belt layers 3a, 3b, the sections of the reinforcements running through the belt assembly 3 are indicated as axially adjacent ovals. The reinforcements can run at angles of several 10° to the circumferential direction and parallel to each other for each belt layer 3a, 3b. The reinforcements in the first and second belt layers 3a, 3b can cross each other, whereby the reinforcements of the first belt layer 3a can run, for example, at an angle of +30° and those of the second belt layer 3b at an angle of -30° to the circumferential direction. Any reinforcements running through the textile cord ply 2b of the carcass 2 and / or the belt bandage 4 are in Fig. 3 is not shown. The cannula 13 of the syringe 12 can be designed in such a way that it can be guided radially through the gaps between the reinforcements. The result of such a guidance of the cannula 13 through the vehicle tire 1 is shown in the example of the second belt layer 3b in Fig. 3, wherein the conductivity channel 7 formed from the conductive substance 11 extends between two strength members arranged in the second belt layer 3b. List of reference symbols 1 vehicle tire 2 carcass 2a inner layer 2a* radial inside of the inner layer 2b textile cord insert 3 Belt bandage 3a first belt layer 3b second belt layer 4 belt bandage 5 treads 6 Tread 7 first conductivity channel 7a radial outer end of the conductivity channel 7b radial inner end of the conductivity channel 8 Tire Equator 9 additional conductivity channels 10 Side wall 11 conductive substance 12 syringes 13 cannula QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 3 727 897 B1

[0003]

Claims

[1] Vehicle tire (1), comprising a carcass (2) with an inner layer (2a), a belt assembly (3) with at least one first belt ply (3a), a belt bandage (4) and a tread (5) with a tread (6), wherein a first conductivity channel (7) extends between a radially outer end (7a) on the tread (6) and a radially inner end (7b), wherein the first conductivity channel (7) extends in the axial direction over less than 10% of an axial width of the vehicle tire (1) and in the circumferential direction over less than 30°, characterized by that the radially inner end (7b) of the first conductivity channel (7) is arranged between a radial position located inside the tread (5) and a radial outer side of the inner layer (2a). [2] Vehicle tyre (1) according to claim 1, characterized bythat the first conductivity channel (7) extends in the axial direction over less than 3% of an axial width of the vehicle tire (1) and in the circumferential direction over less than 1°. [3] Vehicle tyre (1) according to one of claims 1 or 2, characterized by that a cross-sectional area of ​​the first conductivity channel (7) determined perpendicular to the radial direction is between 0.1 mm 2 and 20 mm 2 , preferably between 1 mm 2 and 2 mm 2 measures. [4] Vehicle tyre (1) according to one of claims 1 to 3, characterized by that the radially inner end of the first conductivity channel (7) is arranged between a radial outer side of the belt bandage (4) and a radial outer side of the inner layer (2a). [5] Vehicle tyre (1) according to one of claims 1 to 4, characterized bythat the radially inner end (7b) of the first conductivity channel (7) is located on a radial outer side of the first belt layer (3a), wherein the first belt layer (3a) is the only or the radially lowest belt layer of the belt assembly (3). [6] Vehicle tyre (1) according to one of claims 1 to 5, characterized by that the first conductivity channel (7) is arranged in a region centered around a tire equator (8) with a width of 10% of an axial width of the vehicle tire (1). [7] Vehicle tyre (1) according to one of claims 1 to 6, characterized by that one or more further conductivity channels (9) are arranged in the vehicle tire (1) in the manner of the first conductivity channel (7). [8] Vehicle tyre (1) according to claim 7, characterized by that a total of between 2 and 20, preferably between 5 and 15 conductivity channels (7, 9) are arranged in the vehicle tire (1). [9] Vehicle tyre (1) according to one of claims 7 or 8, characterized by that the first and the further conductivity channels (7, 9) are arranged distributed over the circumference of the vehicle tire (1) in such a way that, regardless of a rotational position of the vehicle tire (1), a radially outer end of a conductivity channel (7, 9) is always arranged within a ground contact surface. [10] Vehicle tyre (1) according to one of claims 7 to 9, characterized by that at least one of the further conductivity channels (9) is arranged outside a region centered around a tire equator (8) with a width of 10% of an axial width of the vehicle tire (1). [11] Method for producing a first conductivity channel (7) according to one of claims 1 to 10, characterized byin that in a first step a vehicle tire (1) without a first conductivity channel (7) and a syringe (12) filled with a conductive substance (11) are provided, wherein in a second step a cannula (13) of the syringe (12) is introduced into the vehicle tire (1) from the position of the radially outer end (3a) to the position of the radially inner end (3b) of the first conductivity channel (7) to be produced, wherein in a third step the cannula (13) is removed again from the vehicle tire (1), the conductive substance (11) being pressed from the syringe (12) into the vehicle tire (1), so that the first conductivity channel (7) is formed from the conductive substance (11) in a vacancy left behind by the cannula (13). [12] Method according to claim 11, wherein the vehicle tire (1) provided in the first step is a green vehicle tire, wherein the conductive substance (11) is vulcanizable and not yet vulcanized up to and including the third step, wherein the vehicle tire (1) is vulcanized in a fourth step together with the conductive substance (11) pressed into the vehicle tire (1).

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