pneumatic tires

Abstract

Pneumatic tire (T) which has the following features: - paired bead areas (1) each having an annular bead core (11) and a bead filler (12) which is arranged outside of the respective bead core (11) in a tire radial direction (D2); - Sidewall areas (2) extending outwards from the bead areas (1) in the tire radial direction (D2); - a tread area (3) which is connected to the outer ends of the sidewall areas (2) in the tire radial direction (D2) to form a tread; and - a carcass layer (4) which is stored between the bead areas (1), - wherein the carcass layer (4) comprises a first layer (41) extending continuously between the bead areas (1) and having opposing end areas (41a, 41b) which are folded upwards from the inner sides in a tire width direction (D1) around the bead cores (11) to the outer sides in the tire width direction (D1), and a second layer (42) which extends continuously in the tire radial direction (D2) outside of the first layer (41) between the bead areas (1) and has opposing end areas (42a, 42b) which are folded upwards from the inner sides in the tire width direction (D1) around the bead cores to the outer sides in the tire width direction (D1), - wherein the first layer (41) has a higher tensile strength than the tensile strength of the second layer (42), and - wherein the end region (41a) of the opposite end regions (41a, 41b) of the first layer (41), which is located on an outside when mounted on a vehicle, is located outside in the tire radial direction (D2) of the end region (41b) of the first layer (41), which is located on an inside when mounted on the vehicle, - wherein the end region (42b), which is located on the inside of the opposing end regions (42a, 42b) of the second layer (42) when mounted on the vehicle, is located on the outside of the end region (42a) of the second layer (42) when mounted on the vehicle in the tire radial direction (D2), - wherein the end region (42b) of the second layer (42) which is arranged on the inside during assembly on the vehicle is arranged on the outside in the tire radial direction (D2) of an end (12a) of the bead filler (12) which is outer in the tire radial direction (D2) and the end region (42a) of the second layer (42) which is arranged on the outside during assembly on the vehicle is arranged on the outside in the tire radial direction (D2) of an end (12a) of the bead filler (12) which is outer in the tire radial direction (D2).

Description

Background of the invention; Field of the invention

[0001] The present invention relates to a pneumatic tire and in particular to a pneumatic tire having a carcass layer formed from two or more carcass layers. Description of the relevant state of the art

[0002] A pneumatic tire generally has bead areas that are present in pairs, sidewall areas that extend outwards from the bead areas in the radial direction of the tire, a tread area that is connected to the outer ends of the sidewall areas in the radial direction of the tire to form a tread, and a carcass layer that is located between the bead areas that are present in pairs.

[0003] In such a pneumatic tire, the carcass layer may in some cases be formed from two carcass layers to increase tire stiffness and improve steering stability (see, for example, the patent document 1 mentioned below). However, the carcass layer formed from two carcass layers leads to an increase in weight and a reduction in rolling resistance.

[0004] Patent document 2 describes a tire with an asymmetrical carcass ply construction. Patent document 3 describes a tire with three carcass plies having different thread densities. State-of-the-art documents, patent documents Patent document 1: JP 2007 - 302 018 A Patent document 2: WO 2014 / 126 701 A Patent Document 3: JP H11-321 217 A Brief description of the invention

[0005] The present invention was made in view of the circumstances described above, and its object is to create a pneumatic tire which can improve steering stability while avoiding an increase in the weight and rolling resistance of the tire.

[0006] The problem underlying the invention is solved by a pneumatic tire having the features of independent claim 1 or independent claim 3. An advantageous further development of the pneumatic tire according to the invention is specified in dependent claim 2.

[0007] According to the invention, the carcass layer comprises a first layer and a second layer, wherein the first layer has a higher tensile strength than the second layer and wherein the first layer has a greater influence on stiffness and weight than the second layer.

[0008] Since the end area located on the outside of the vehicle during installation is positioned outside of the end area of ​​the first layer that is located on the inside of the vehicle during installation, the upwardly folded height of the first layer located on the outside of the vehicle during installation is relatively greater.

[0009] In this way, the stiffness of the sidewall section located on the outside of the vehicle during installation can be increased, whereby a load is exerted on the outer sidewall section during cornering, thus improving steering stability. On the other hand, the height of the first layer, located on the inside of the vehicle during installation, is relatively lower when folded upwards, thus avoiding an increase in weight and rolling resistance.

[0010] In one embodiment, the end region of the first layer, which is arranged on the outside of the vehicle during assembly, can be positioned on the outside of an end of the bead filler that is outer in the tire radial direction, and the end region of the first layer, which is arranged on the inside of the vehicle during assembly, can be positioned on the inside of an end of the bead filler that is outer in the tire radial direction.

[0011] This training makes it possible to effectively improve steering stability while avoiding an increase in weight and rolling resistance.

[0012] According to the present invention, the end region which is arranged on the inside of the opposing end regions of the second layer when mounted on the vehicle can be arranged on the outside of the end region of the second layer which is arranged on the outside when mounted on the vehicle in the tire radial direction.

[0013] During this training, the tire exhibits an overall satisfactory balance between the left and right sides, thus improving steering stability.

[0014] In one embodiment, the end region of the second layer, which is located on the inside during assembly on the vehicle, can be arranged on the outside of an end of the bead filler that is outer in the tire radial direction, and the end region of the second layer, which is located on the outside during assembly on the vehicle, can be arranged on the inside of an end of the bead filler that is outer in the tire radial direction.

[0015] During this training, the tire exhibits an overall satisfactory balance between the left and right sides, thus improving steering stability.

[0016] According to the present invention, the end region of the first layer, which is arranged on the outside of the vehicle during assembly, can be arranged on the outside of the end region of the second layer in the tire radial direction.

[0017] In this design, the first layer, which has the relatively higher tensile strength, covers the end area of ​​the second layer, resulting in an improvement in durability. Brief description of the drawings

[0018] The drawings show: Fig. 1 a sectional view along a tire meridian, in which an example of a pneumatic tire is schematically represented; Fig. 2 a sectional view along a tire meridian in which a pneumatic tire according to an embodiment of the invention is schematically shown; Fig. 3 a sectional view along a tire meridian in which a pneumatic tire according to a further embodiment of the invention is schematically represented; and Fig. 4 a sectional view along a tire meridian, in which a pneumatic tire according to a further embodiment of the invention is schematically shown. Detailed description of preferred embodiments

[0019] In the following, embodiments of the present invention are described with reference to the drawings.

[0020] A in Fig. 1 The depicted (non-claiming) pneumatic tire T has paired bead areas 1, sidewall areas 2 which extend outwards from the bead areas 1 in a tire radial direction D2, a tread area 3 which is connected to the outer ends of the sidewall areas 2 in the tire radial direction D2 to form a tread, a carcass layer 4 which is located between the paired bead areas 1, and a belt layer 5 which is arranged outside the carcass layer 4 in the tread area 3 in the tire radial direction D2.

[0021] In Fig. In this context, the tire width direction D1 is a horizontal direction. The tire radial direction D2 is a diameter direction of the tire 1, and the tire circumferential direction is a direction around a tire rotation axis. A tire equatorial plane S1 is a plane that is orthogonal to the tire rotation axis and located at a center in the tire width direction D1, and a tire meridional plane is a plane that includes the tire rotation axis and is orthogonal to the tire equatorial plane S1.

[0022] Each of the paired bead areas 1 has a bead core 11, which is a bundle of steel wires with a ring-shaped form in the circumferential direction of the tire, and a bead filler 12, which is arranged outside the bead core 11 in the radial direction D2 of the tire.

[0023] The belt layer 5 has at least two layers of belt layers 51 and 52. In the present embodiment, the belt layer 5 has two layers of belt layers 51 and 52. Each of the belt layers 51 and 52 has a plurality of belt cords arranged parallel to each other and a covering rubber material covering the belt cords.

[0024] The respective belt layers 51 and 52 are layered in such a way that the groups of belt cords in the respective layers are inclined at predetermined angles of inclination (e.g. 15° to 35°) to the tire circumference direction in opposite orientations and cross each other.

[0025] Suitable materials for the belt cords include organic fibers, such as polyester, rayon, nylon, and aramid, or metals, such as steel. A belt reinforcement layer, formed from cords running essentially in the direction of the tire's circumference and covered with rubber material, can be arranged at an outer periphery of the belt layer 5.

[0026] The pneumatic tire T according to the embodiment has an asymmetrical design with respect to the tire equatorial plane S1. The pneumatic tire T is a tire that is to be mounted on a vehicle in a predetermined direction, and the direction from the left and right sides of the pneumatic tire T to the vehicle is specified when the pneumatic tire T is mounted on a rim. A tread pattern formed on the outer surface of the tire in the tread area 3 can have a symmetrical or an asymmetrical structure with respect to the tire equatorial plane S1.

[0027] The sidewall areas 2 have markings indicating the directions in which the tire should be mounted on the vehicle. Specifically, the sidewall areas 2 have markings on their outer surfaces indicating the directions in which the tire should be mounted on the vehicle.

[0028] In this embodiment, one of the sidewall areas 2, which is located on an outer side (left side) when the tire is mounted on the vehicle, has Fig. 1) is arranged, a sign indicating that this side is to be arranged on the outside of the vehicle (e.g. “OUTSIDE”), and the other side wall area 2, which is on an inside (right side in Fig. 1) is arranged, has a sign indicating that this side is to be arranged on the inside of the vehicle (e.g. “INSIDE”).

[0029] In the tire width direction D1, a direction that points outwards when mounted on the vehicle is referred to as "vehicle outside direction D11", and a direction that points inwards when mounted on the vehicle is referred to as "vehicle inside direction D12".

[0030] The carcass layer 4 has a first carcass layer 41 (corresponding to a first layer) and a second carcass layer 42 (corresponding to a second layer). On the inner side of the carcass layer 4, an inner lining rubber material 6 with excellent properties for preventing gas penetration is arranged in order to maintain air pressure.

[0031] Each of the first carcass ply 41 and the second carcass ply 42 has a multitude of ply cords arranged in one direction essentially orthogonal to the tire's circumferential direction, as well as a cover ply rubber material covering the ply cords. Organic fibers such as polyester, rayon, nylon, and aramid are used for the ply cords.

[0032] The first carcass ply 41 has a higher tensile strength than the second carcass ply 42. Here, the tensile strength of the first carcass ply 41 refers to the load under which the ply cords break during a tensile test. The same applies to the tensile strength of the second carcass ply 42. The tensile strength can be adjusted, for example, by changing the cord diameters of the ply cords, the density at which the ply cords are arranged per unit width, and similar factors.

[0033] In other words, to increase tensile strength, it is possible to increase the cord diameter of the ply cords or to increase the density at which the ply cords are arranged per unit width. Generally, high tensile strength means a heavier carcass ply per unit width.

[0034] The first carcass layer 41 extends continuously between the bead areas 1 and has opposing end areas 41a and 41b, which are each folded upwards from an inside in the tire width direction D1 around the bead cores 11 to an outside in the tire width direction D1.

[0035] Of the opposing end regions 41a and 41b of the first carcass layer 41, the end region 41a, which is located on the outside during assembly on the vehicle, is located outside in the tire radial direction D2 of the end region 41b, which is located on the inside during assembly on the vehicle.

[0036] The end region 41a, which is located on the outside of the vehicle during installation, is positioned on the outside of an end 12a of the bead filler 12 that is also located on the outside of the tire radial direction D2. In contrast, the end region 41b, which is positioned on the inside of the vehicle during installation, is located on the inside of the tire radial direction D2 of the end 12a of the bead filler 12 that is also located on the outside of the tire radial direction D2.

[0037] As a result, the upwardly folded height H1a of the first carcass layer 41 arranged on the outside during assembly on the vehicle (the distance in the tire radial direction D2 between an inner end 11a of the bead core 11 in the tire radial direction D2 and the end area 41a) is relatively larger.

[0038] In this way, the stiffness of the side wall area 2, which is located on the outside of the vehicle during assembly, can be increased, and steering stability can be improved when a load is applied to the side wall area 2 on the outside.

[0039] In contrast, the upwardly folded height H1b of the first carcass layer 41, which is arranged on the inside during assembly on the vehicle (a distance in the tire radial direction D2 between an inner end 11a of the bead core 11 in the tire radial direction D2 and the end region 41b), is relatively smaller. This prevents an increase in weight and rolling resistance.

[0040] The second carcass layer 42 extends continuously between the bead areas 1 and has opposing end areas 42a and 42b, which are each folded upwards from an inside in the tire width direction D1 around the bead cores 11 to an outside in the tire width direction D1.

[0041] The second carcass ply 42 is adjacent to the outer side of the first carcass ply 41 in the tire radial direction D2. In other words, the second carcass ply 42 and the first carcass ply 41 are arranged in this order outwards from the peripheries of the bead cores 11.

[0042] Of the opposing end regions 42a and 42b of the second carcass layer 42, the end region 42b, which is located on the inside during assembly on the vehicle, is located outside in the tire radial direction D2 of the end region 42a, which is located on the outside during assembly on the vehicle.

[0043] In other words, the upwardly folded height H2b of the second carcass layer 42 arranged on the inside during assembly on the vehicle (the distance in the tire radial direction D2 between the inner end 11a of the bead core 11 in the tire radial direction D2 and the end region 42b) is greater than the upwardly folded height H2a of the second carcass layer 42 arranged on the outside during assembly on the vehicle (the distance in the tire radial direction D2 between the inner end 11a of the bead core 11 in the tire radial direction D2 and the end region 42a).

[0044] The end region 42b, which is located on the inside of the vehicle during installation, is positioned outside the outer end 12a of the bead filler 12 in the tire radial direction D2. In contrast, the end region 42a, which is positioned on the outside of the vehicle during installation, is located inside the tire radial direction D2 of the outer end 12a of the bead filler 12 in the tire radial direction D2.

[0045] In the pneumatic tire T according to the embodiment, the left and right upwardly folded heights H2a and H2b of the second carcass layer 42 have an inverse size relationship to the size relationship that exists between the left and right upwardly folded heights H1a and H1b of the first carcass layer 41.

[0046] As a result, the tire has a satisfactory overall balance between the left and right sides, leading to improved steering stability. In the case of the pneumatic tire T, the stiffness difference between the sidewall section 2 located on the outside of the vehicle and the sidewall section 2 located on the inside of the vehicle is preferably 40% or less. A large stiffness difference leads to a loss of uniformity.

[0047] The end region 41a of the first carcass layer 41, which is located on the outside during assembly on the vehicle, is positioned outside the end region 42a of the second carcass layer 42, which is also located on the outside during assembly on the vehicle, in the tire radial direction D2. In this way, the first carcass layer 41, which has a relatively higher tensile strength, covers the end region 42a of the second carcass layer 42, thereby improving durability.

[0048] The end region 41a of the first carcass layer 41, which is arranged on the outside of the vehicle during assembly, can be in contact with an inner circumferential surface of an end region 5a of the belt layer 5, which is arranged on the outside of the vehicle during assembly.

[0049] In this way, the first carcass layer 41, which has the relatively higher tensile strength, is located on one side of a tire outer surface in the shoulder area which is located on the outside during assembly on the vehicle, resulting in an improvement in cut resistance and puncture resistance.

[0050] Although the embodiment according to the present invention has been described above with reference to the drawings, specific structures should not be understood as being limited to those of this embodiment. The scope of the invention is defined not only by the above description of the embodiment but also by the claims and includes meanings equivalent to the claims as well as all modifications within the scope of the claims.

[0051] It is also possible to use structures employed in the embodiment described above in other embodiments as well. Specific structures in the respective areas are not limited to those in the embodiment described above, but can be varied in various ways within the scope of the invention. Other embodiments

[0052] (1) As in Fig. As shown in Figure 2, in the case of a pneumatic tire T, an end region 42a arranged on the outside during mounting on a vehicle can be arranged in the tire radial direction D2 outside of an end 12a of a bead filler 12 that is outer in the tire radial direction D2.

[0053] In this way, it is possible to further increase the stiffness of a sidewall area 2 arranged on the outside during assembly on the vehicle, thereby improving steering stability. An end area 41a of a first carcass layer 41, arranged on the outside during assembly on the vehicle, is preferably located outside of the end area 42a of the second carcass layer 42 in the tire radial direction D2.

[0054] (2) As in Fig. As shown in Figure 3, in the case of a pneumatic tire T, an end area 42b arranged on the inside during mounting on a vehicle can be located in the tire radial direction D2 on the inside of an outer end 12a of the bead filler 12 in the tire radial direction D2.

[0055] This results in a lower height of the second carcass layer 42, which is arranged on the inside during assembly on the vehicle, thus further suppressing an increase in weight and rolling resistance.

[0056] (3) As in Fig. As shown in Figure 4, in the case of a pneumatic tire T, an end region 41b of a first carcass layer 41, arranged on the inside during mounting on a vehicle, can be located on the outside of an end 12a of the bead filler 12 in the tire radial direction D2.

Claims

[1] Pneumatic tire (T) which has the following features: - paired bead areas (1) each having an annular bead core (11) and a bead filler (12) which is arranged outside of the respective bead core (11) in a tire radial direction (D2); - Sidewall areas (2) extending outwards from the bead areas (1) in the tire radial direction (D2); - a tread area (3) which is connected to the outer ends of the sidewall areas (2) in the tire radial direction (D2) to form a tread; and - a carcass layer (4) which is stored between the bead areas (1), - wherein the carcass layer (4) comprises a first layer (41) extending continuously between the bead areas (1) and having opposing end areas (41a, 41b) which are folded upwards from the inner sides in a tire width direction (D1) around the bead cores (11) to the outer sides in the tire width direction (D1), and a second layer (42) which extends continuously in the tire radial direction (D2) outside of the first layer (41) between the bead areas (1) and has opposing end areas (42a, 42b) which are folded upwards from the inner sides in the tire width direction (D1) around the bead cores to the outer sides in the tire width direction (D1), - wherein the first layer (41) has a higher tensile strength than the tensile strength of the second layer (42), and - wherein the end region (41a) of the opposite end regions (41a, 41b) of the first layer (41), which is located on an outside when mounted on a vehicle, is located outside in the tire radial direction (D2) of the end region (41b) of the first layer (41), which is located on an inside when mounted on the vehicle, - wherein the end region (42b), which is located on the inside of the opposing end regions (42a, 42b) of the second layer (42) when mounted on the vehicle, is located on the outside of the end region (42a) of the second layer (42) when mounted on the vehicle in the tire radial direction (D2), - wherein the end region (42b) of the second layer (42) which is arranged on the inside during assembly on the vehicle is arranged on the outside in the tire radial direction (D2) of an end (12a) of the bead filler (12) which is outer in the tire radial direction (D2) and the end region (42a) of the second layer (42) which is arranged on the outside during assembly on the vehicle is arranged on the outside in the tire radial direction (D2) of an end (12a) of the bead filler (12) which is outer in the tire radial direction (D2). [2] Pneumatic tire (T) according to claim 1, wherein the end region (41a) of the first layer (41) arranged on the outside of the tire is arranged in the tire radial direction (D2) outside of the end region (42a) of the second layer (42) arranged on the outside of the tire when mounted on the tire. [3] Pneumatic tire (T) which has the following features: - paired bead areas (1) each having an annular bead core (11) and a bead filler (12) which is arranged outside of the respective bead core (11) in a tire radial direction (D2); - Sidewall areas (2) extending outwards from the bead areas (1) in the tire radial direction (D2); - a tread area (3) which is connected to the outer ends of the sidewall areas (2) in the tire radial direction (D2) to form a tread; and - a carcass layer (4) which is stored between the bead areas (1), - wherein the carcass layer (4) comprises a first layer (41) extending continuously between the bead areas (1) and having opposing end areas (41a, 41b) which are folded upwards from the inner sides in a tire width direction (D1) around the bead cores (11) to the outer sides in the tire width direction (D1), and a second layer (42) which extends continuously in the tire radial direction (D2) outside of the first layer (41) between the bead areas (1) and has opposing end areas (42a, 42b) which are folded upwards from the inner sides in the tire width direction (D1) around the bead cores to the outer sides in the tire width direction (D1), - wherein the first layer (41) has a higher tensile strength than the tensile strength of the second layer (42), and - wherein the end region (41a) of the opposite end regions (41a, 41b) of the first layer (41), which is located on an outside when mounted on a vehicle, is located outside in the tire radial direction (D2) of the end region (41b) of the first layer (41), which is located on an inside when mounted on the vehicle, - wherein the end region (42b), which is located on the inside of the opposing end regions (42a, 42b) of the second layer (42) when mounted on the vehicle, is located on the outside of the end region (42a) of the second layer (42) when mounted on the vehicle in the tire radial direction (D2), - wherein the end region (42b) of the second layer (42) which is arranged on the inside during assembly on the vehicle is arranged on the inside in the tire radial direction (D2) of an outer end (12a) of the bead filler (12) in the tire radial direction (D2) and the end region (42a) of the second layer (42) which is arranged on the outside during assembly on the vehicle is arranged on the inside in the tire radial direction (D2) of an outer end (12a) of the bead filler (12) in the tire radial direction (D2).

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