HEAVY-LOAD VEHICLE

Abstract

The invention relates to a heavy-load vehicle comprising at least one axle unit, the or each axle unit having at least one wheel, each wheel having at least one tire, at least one tire being a tubeless radial tire. The tubeless radial tire has an outer diameter of less than 755 millimeters (mm), and is adapted and configured for an internal pressure of at least 10 bar. In some instances, when used as a single tire, the tubeless radial tire has a load-bearing capacity per millimeter section width at a speed of 60 kilometers per hour (km/h) of at least 11 kilograms (kg).

Claims

1. A heavy-load vehicle comprising at least one axle unit, each axle unit having at least one wheel, each wheel having at least one tire, at least one tire being a tubeless radial tire, wherein the tubeless radial tire has an outer diameter of less than 755 millimeters (mm), and is adapted and configured for an internal pressure of at least 10 bar.

2. The heavy-load vehicle of claim 1, wherein the tubeless radial tire has an outer diameter of less than 735 millimeters (mm).

3. The heavy-load vehicle of claim 1, wherein the tubeless radial tire has, when used as a single tire, a load-bearing capacity per millimeter section width at a speed of 60 kilometers per hour (km/h) of at least 12.5 kilograms (kg).

4. The heavy-load vehicle of claim 1, wherein, the tubeless radial tire has at a speed of 60 kilometers per hour (km/h) a load-bearing capacity per square millimeter section width times section height of at least 80 grams (g).

5. The heavy-load vehicle of claim 1, wherein a wire forming at least one bead ring of the tubeless radial tire includes a plurality of windings, wherein immediately adjacent wire sections of the plurality of windings are arranged in a triangular constellation.

6. The heavy-load vehicle of claim 5, wherein a steel wire of at least one bead ring is arranged when seen in a cross-section extending orthogonal to a circumferential direction around a rotational axis of the tubeless radial tire according to a hexagonal shape.

7. The heavy-load vehicle of claim 5, characterized in that at least one bead ring includes at least 44, windings of the bead wire.

8. The heavy-load vehicle of claim 1, wherein at least one steel cord of a carcass of the tubeless radial tire comprises at least 20 steel filaments.

9. The heavy-load vehicle of claim 1, wherein a belt of the tubeless radial tire comprises a plurality of belt layers, wherein an outermost belt layer has a smaller width than a second-outermost belt layer, wherein the second-outermost belt layer has a smaller width than a third-outermost belt layer.

10. The heavy-load vehicle of claim 1, wherein the outermost layer is replaced by two cap ply strips arranged in a side-by-side arrangement with the second-outermost layer.

11. The heavy-load vehicle of claim 9, wherein the steel cords of the outermost belt layer extend substantially in a circumferential direction.

12. The heavy-load vehicle of claim 9, wherein the steel cords of the innermost belt layer confine an angle of less than 45 degrees (45°) with the circumferential direction.

13. The heavy-load vehicle of claim 8, wherein one or more of (A) the carcass, (B) the third-outermost belt layer, or (C) the innermost belt layer has an ends-per-decimeter value of at least 50 ends per decimeter.

14. The heavy-load vehicle of claim 5, wherein a bead apex is located adjacent to and radially outward of at least one of the bead rings.

15. The heavy-load vehicle of claim 5, wherein a shoulder apex is located in at least one of one or more wedges between a belt and a carcass, wherein the heavy-load vehicle includes a second shoulder apex section covering the shoulder apex and the belt from above.

16. The heavy-load vehicle of claim 1, wherein one or more of (A) a thickness of a shoulder area amounts to a maximum of 35 millimeters (mm), (B) an undertread thickness of the tubeless radial tire amounts to a maximum of 5 mm, (C) the minimum thickness of a side wall of the tire amounts to a maximum of 10 mm, or (D) the thickness measured from a bottom of a central circumferential profile groove to an upper edge of the belt amounts to a maximum of 5 mm.

17. The heavy-load vehicle of claim 1, having, when used as a single tire, a load-bearing capacity per millimeter section width at a speed of 60 kilometers per hour (km/h) of at least 11 kilograms (kg).

18. The heavy-load vehicle of claim 9, wherein the plurality of belt layers are arranged symmetrically one above the other.

19. The heavy-load vehicle of claim 10, wherein at least one of the two cap ply strips is a predetermined lateral distance from the second-outermost layer.

20. The heavy-load vehicle of claim 14, wherein the bead apex is made from high elasticity modulus rubber and further including at least two bead apex sections, a first bead apex section being located adjacent to the bead ring and a second bead apex section being located a distance from the bead ring.

Description

[0072] In the following, the invention will be described in more detail with respect to a specific embodiment referring to the enclosed drawings, in which:

[0073] FIG. 1 shows a cross-section of a tire according to the invention;

[0074] FIG. 2 show a cross-sectional view of a bead ring of the tire of FIG. 1;

[0075] FIG. 3 show cross-sectional views of steel cord used in the carcass of the tire of FIG. 1;

[0076] FIGS. 4 to 6 show cross-sectional views of steel cords used in the various layers of the belt of the tire of FIG. 1;

[0077] FIG. 7 shows a diagram of the tensile strength versus steel filament diameter characteristic of HT steel and NT steel;

[0078] FIG. 8 shows a perspective view of a heavy-load vehicle according to the invention having pendular axle units;

[0079] FIG. 9 shows a front view of a heavy-load vehicle according to the invention having individually suspended axle units;

[0080] FIG. 10 shows a front view of a heavy-load vehicle according to the invention a beam axle unit; and

[0081] FIG. 11 shows a tire cross-section similar of FIG. 1 of a tire according to an alternative embodiment of the invention.

[0082] In FIG. 1, a tire according to the invention is generally indicated by reference numeral 100. The tire 100 has a base wall 102, and two side walls 104.

[0083] One end of the side walls 104 is connected to the base wall 102 in a shoulder region 106, while the respective other end of the side walls 104 terminates in a bead region 108 adapted and configured for connection with a rim 110.

[0084] s Like conventional tires, the tire 100 according to the invention is mainly made from rubber material 112 reinforced by specific elements made from steel cord and steel wire.

[0085] In particular, the tire 100 according to the invention has a carcass 114 made from steel cords 116, which extend from one bead region 108 through the allocated side wall 104, the base wall 102 and the respective other side wall 104 to the respective other bead region 108. The extension of the steel cords 116 having only components parallel to the direction of the rotational axis A of the tire 100 and the rim 110, respectively, an in radial direction R, however, no or substantially no component in circumferential direction C. In other words, the tire 100 is a radial tire.

[0086] The base wall 102 has a tread 118 having a plurality of grooves 120 forming the tread pattern. A belt 122 having four belt layers 124, 126, 128 and 130 and reinforcing the base wall 102 is arranged between the bottom of the grooves 120 and the carcass 114. As will be explained below in more detail, each of the four belt layers 124, 126, 128 and 130 is made from steel cord.

[0087] Finally, each of the bead regions 108 includes a bead ring 132 made from steel wire. The bead rings 132 are at least partly enveloped by the carcass 114. Furthermore, an inner reinforcement layer 134 is located between the bead ring 132 and the carcass 114, and an outer reinforcement layer 136 is located at the side of the carcass 114 facing away from the bead ring 132. The inner reinforcement layer 134 and the outer reinforcement layer 136 are both made from steel cord.

[0088] As the tire according to the present invention has a small outer diameter OD of less than 755 mm, preferably of less than 735 mm, more preferably of less than 715 mm, for a high load-bearing capacity per millimeter section width SW at a speed of 60 km/h of at least 11 kg, preferably of at least 12.5 kg, the side walls 104, the shoulder regions 106, and the bead regions 108 have to be able to resist to higher flexing stress than convention tires.

[0089] This is in particular true for a specific embodiment of the tire according to the present invention, which is adapted and configured to be used together with standard rims 110 having an outer rim diameter RD 01444.5 mm (17.5 inches), and thus having a small section height SH. The relevant point for determining the outer rim diameter RD and the section height SH is the transition point between the tire seat surface 110a and the radial outer flange 110b of the rim 110.

[0090] In order to strengthen the bead region 108, the bead rings 132 are made from a steel wire 133 having a diameter of 1.55 mm. According to a specific embodiment, shown in FIG. 2, the wire is wound 58 times and the wire windings are arranged according to a hexagonal 7-8-9-10-9-8-7 configuration. It is, however, also conceivable that the bead rings 132 include less windings, e.g. only 51 or only 44 windings. In FIG. 2, the overall hexagonal configuration is indicated by a dashed line, and in FIG. 1 only the overall hexagonal configuration of the bead rings 132 is shown.

[0091] In order to further strengthen the bead region 108, a bead apex 138 may be located adjacent to and radially outward of each of the bead rings 132. The bead apex 138 is a profile having a generally triangular shape and mating on its one side against the bead ring 132 and on a second side against the carcass 114, while the third side extends from the end of the carcass 114 to the widest section of the carcass 114. Preferably, the bead apex 138 is made from high elasticity modulus rubber.

[0092] Analogously, a shoulder apex 140 may be located in both of the wedges between the belt 122 and the carcass 114 for strengthening the shoulder region 106 of the tire 100. Preferably, the shoulder apex 140 is made from high elasticity modulus rubber, for example from a slightly different rubber material as the bead apex 132.

[0093] In contrast to the bead apex 138 and the shoulder apex 140, the inner liner 142 of the tire 100 located inside the carcass 114 and forming the radially inner surface of the tire 100 may be formed from a butyl rubber, preferably a halo-butyl rubber, the halogen preferably being chlorine.

[0094] Besides the afore-mentioned rubber materials used for the inner liner 142, the bead apex 138 and the shoulder apex 140, conventional rubber mixtures may be used for remaining rubber material 112 of tire 100.

[0095] In order to strengthen the side walls 104, the steel cords 116 of the carcass 114 may, according to the specific embodiment shown in FIG. 3, be made from steel cord having a 3+9+15+1 configuration, in particular a 3+9+15*0.175+0.15 configuration. In addition or as an alternative, the carcass 114 may have an ends per decimeter value of at least 50, preferably of at least 55, more preferably of at least 60 ends per decimeter. As a steel cord 116 having the afore-mentioned configurations and/or the afore-mentioned ends per decimeter value provides a sufficient strengthening of the side wall 104, the steel cord 116 may be made from NT steel.

[0096] The steel cord 116 used for manufacturing the carcass 114 may be used for manufacturing the inner and outer reinforcement layers 134, 136 as well.

[0097] In order to strengthen the shoulder regions 106, the belt 122 has a chamfer to both sides, i.e. the radially outermost belt layer 130 has a smaller width than the second-outermost belt layer 128, which in turn had a smaller width than the third-outermost belt layer 126. Furthermore, the three belt layers 130, 128 and 126 are arranged symmetrically one above the other, in order provide the same chamfer for both shoulder regions 106.

[0098] According to the specific embodiment shown in FIG. 1, the belt 122 includes four belt layers 124, 126, 128 and 130, the innermost belt layer 124 being configured as a combination of a transition layer and a working layer, i.e. not as a pure transition layer. This combined function of the innermost belt layer 124 is achieved by the angle, which its steel cords 144 confine with the circumferential direction C. According to a specific embodiment, the steel cords 144 of the innermost belt layer 124 confine an angle of less than 45°, preferably less than 35°, more preferably less than 25°, with the circumferential direction C.

[0099] Moreover, the steel cords 144 may have the 3+6 configuration shown in FIG. 4, in particular a 3*0.20+6*0.35 configuration, and may be made from HT steel. Furthermore, the innermost belt layer may 124 has an ends per decimeter value of at least 50, preferably of at least 55, more preferably of at least 60 ends per decimeter.

[0100] An innermost belt layer 124 of the afore-discussed construction allows to reduce the shear stress between the other belt layers 126, 128 and 130, and thus further assists in strengthening the shoulder regions 106.

[0101] The third-outermost belt layer 126 may include steel cords 146 having the same characteristics as the steel cords 144 of the innermost belt layer 124, however, confine a more acute angle with the circumferential direction C, e.g. an angle of 15°.

[0102] The second-outermost belt layer 128 may include steel cords 148 manufactured as HI steel cords and having the configuration shown in FIG. 5, in particular a 5*0.30 configuration. As the steel cords 146 of the third-outermost belt layer 126 the steel cords 148 may confine an acute angle with the circumferential direction C, e.g. an angle of 15°.

[0103] Finally, the steel cords 150 of the outermost layer 130 may be manufactured as HE steel cords and, like the steel cords of a cap ply, extend substantially in the circumferential direction C, i.e. confine with the circumferential direction C an angle of 0°, which reduces the tire growth under the inflation pressure of the tire 100, which may amount to up to 10 bar or even more, and under rotation in operation. Furthermore, the steel cords 150 may have the 3+7 configuration shown in FIG. 6. Moreover, the steel cords 150 of the outermost belt layer 130 may be arranged with a density of about 40 cords per decimeter layer width.

[0104] FIG. 11 shows a tire cross-section of a tire according to an alternative embodiment of the invention. The tire of FIG. 11 substantially corresponds to the tire of FIG. 1. As a consequence, analogous parts are designated by the same reference numerals as in FIG. 1, however increased by 100. Furthermore, only the differences between the tire 200 of FIG. 11 and the tire 100 of FIG. 1 will be described in the following. With respect to the description of all other parts, it is referred to the description of the embodiment of FIG. 1.

[0105] First of all, the tire 200 of FIG. 11 comprises two cap ply strips 230A and 230B which are located in a side by side arrangement with the second-outermost layer 228, in order to prevent an exceedingly high diameter growth under pressure and during operation, i.e. rotation of the tire in contact with the underground. These two 230A and 230B replace the single cap ply strip 130 located in the center of the tire cross-section of the tire 100 of FIG. 1. Preferably, the cap ply strips 230A, 230B have a predetermined lateral distance, of e.g. a maximum of 5 mm, from the second-outermost layer 228.

[0106] Furthermore, each of the cap ply strips 230A, 230B may include two cap ply layers arranged one above the other in a radial direction R of the tire 200.

[0107] In this embodiment the innermost layer 224 may have a width of about 168 mm, the second-outermost layer 228 may have a width of about 110 mm, and the third-outermost layer 226 may have a width of about 190 mm, while the cap play strips may have a width of about 29 mm.

[0108] As a second difference, the bead apex 238 may include at least two bead apex sections 238a, 238b, a first bead apex section 238a being located adjacent to the bead ring 232 and a second bead apex section 238b being to located distant from the bead ring 232. Providing two or more bead apex sections 238a, 238b allows a greater variability for influencing the flexibility of the tire 200. For example, the elasticity modulus of the material of the first bead apex section 238a may be selected to be higher than the elasticity modulus of the material of the second bead apex section 238b.

[0109] Thirdly, the shoulder apex 240 may include at least two shoulder apex sections 240a, 240b, a first shoulder apex section 240a corresponding to the above-discussed, preferably sickle-shaped, shoulder apex 140 of the tire 100 of FIG. 1, and a second shoulder apex section 240b covering the first shoulder apex section 240a and the belt 222 from above, i.e. from radially outward. Providing the second shoulder apex section 240b which covers the belt 222 from above allows to deal with the stress emanating from the belt 222 in the direction of the should in a more effective manner. As such, although the elasticity modulus of the materials of the first and second shoulder apex sections 240a, 240b may be different, it is also conceivable that they are equal.

[0110] In order to reduce the stress in the shoulder regions 206 of the tires 200, the thickness SHT of the shoulder area 206 may amount to a maximum of 35 mm and/or the undertread thickness UTT of the tire 200 may amount to a maximum of 5 mm and/or the minimum thickness SWT of the side wall 204 of the tire 200 may amount to a maximum of 10 mm and/or the thickness GBT measured from the bottom of the central circumferential profile groove 120 to the upper edge of the belt 222 may amount to a maximum of 5 mm.

[0111] It is to be understood that not all of these differences have to be applied simultaneously. For example, starting from the embodiment of FIG. 1, only the first and second bead apex regions 238a, 238b and the first and second shoulder apex regions 240a, 240b could be applied together with the design rules of the shoulder thickness SHT and/or the undertread thickness UTT and/or the side wall thickness SWT. In this context the outermost belt layer could have a width of about 110 mm, the second-outermost belt layer could have a width of about 178 mm, the third-outermost belt layer could have a width of about 190 mm, and the innermost belt layer could have a width of about 168 mm.

[0112] FIG. 7 shows the tensile strength versus steel filament diameter characteristic of HT steel filaments and NT steel filaments. For example, this characteristic may described by the following equation:

TS=X−2000 N/mm.sup.3.Math.D

[0113] wherein TS designates the tensile strength in N/mm.sup.2, ID the filament diameter in millimeters, and X is a parameter which may have a value of between 3600 N/mm.sup.3 and 4000 N/mm.sup.3 for HT steel and between 3040 N/mm.sup.3 and 3440 N/mm.sup.3 for NT steel.

[0114] Referring now to FIGS. 8 to 10, the invention further relates to a heavy-load vehicle.

[0115] FIG. 8 shows a heavy-load vehicle 200 with a plurality of axle lines 202. Each axle line 202 has two axle units 204, namely a first axle unit 204 located at the left side of the heavy-load vehicle 200 and a second axle unit 204 located at the right side of the heavy-load vehicle 200. Furthermore, each of the axle units 204 has four wheels, each of the wheels 206 including one tubeless radial tire 100 according to the invention.

[0116] It would, however, also be conceivable that the pendular axle unit 204 has only two wheels 206, one on each side of the pendular axle, each of the wheels 206 including one tubeless radial tire 100 according to the invention.

[0117] Although the axle units 204 are pendular axle units, the invention is not limited to this specific type of axle units.

[0118] As a further example, FIG. 9 shows a heavy-load vehicle 300 having two individually suspended axle units 304, in particular MacPherson type axle units. Each of the axle units 304 has two wheels 306, and each of the wheels 306 including one tubeless radial tire 100 according to the invention.

[0119] It would, however, also be conceivable that the individually suspended axle units 304 has only one wheel 306 with one tubeless radial tire 100 according to the invention.

[0120] Furthermore, FIG. 10 shows a heavy-load vehicle 400 having a beam axle unit 404. The axle unit 404 has four wheels 406, each of the wheels 406 including one tubeless radial tire 100 according to the invention.

[0121] It would, however, also be conceivable that the beam axle unit 404 has only two wheels 406, one on each side of the vehicle 400, each of the wheels 406 including one tubeless radial tire 100 according to the invention.

[0122] Moreover, the suspension of the axle units may be a mechanical suspension and/or a spring suspension and/or an air suspension and/or a hydraulic suspension.

[0123] As the general construction of heavy-load vehicles having rigid axle units and/or individually suspended axle units and/or pendular axle units is known in the art, a detailed description of these heavy-load vehicles and axle units, respectively, is omitted here for the sake of simplicity.

[0124] Generally, FIGS. 8 to 10 show only exemplary embodiments of a heavy-load vehicles. In particular, the heavy-load vehicle of the invention may be a self-propelled vehicle or a towed vehicle, including fifth wheel trailers and/or axle supported trailers. Further, the axle units of the heavy-load vehicle may be force-steered axle units and/or friction-steered axle units and/or rigid axle units.

[0125] With respect to the specific embodiments 1 to 4 indicated in Tables 1 to 4, it is to be noted, that embodiments 1 and 4 of Tables 1 and 4 are optimized embodiments, whereas embodiments 2 and 3 of Tables 2 and 3 have been derived from embodiment 1 by simply changing the tire diameter, while maintaining all materials and internal dimensions as in embodiment 1. As a consequence, not the theoretically available load-bearing capacity could be used. Rather, an increased stress was compensated by reducing the load-bearing capacity in order to achieve the same operation safety as for embodiment 1.

TABLE-US-00001 TABLE 1 specific example 1 according to the Invention General Parameters Construction Radial/Tubeless Design Pressure 10 bar Design OD 712 mm Design SH 134 mm Design SW 238 mm Sidewall Protector 4 mm Rim Size 6.75 × 17.5 Max. Load at 60 km/h 3300 kg Carcass Steel Cord Type 3 + 9 + 15*0.175 + 0.15NT Tensile Strength 1720 N Cord EPD 60 Bead Number of Windings 58 Configuration Hexagonal 7- . . . -10- . . . -7 Tensile Strength 3900 N Belt Belt Layer #1 (innermost) #2 (third-outermost) Belt Width 160 mm 180 mm Steel Cord Type 3*0.20 + 6*0.35HT 3*0.20 + 6*0.35HT Tensile Strength 1870 N 1870 N Cord EPD 60 60 Angle 24° 15° Belt Layer #3 (second-outermost) #4 (outermost) Belt Width 100 mm 29 mm Steel Cord Type 5*0.30HI 3 + 7*0.20HE Tensile Strength 1875 N 1360 N Cord EPD 40 NA Angle 15° 0°

TABLE-US-00002 TABLE 2 specific example 2 according to the invention General Parameters Construction Radial/Tubeless Design Pressure 10 bar Design OD 755 mm Design SH 155 mm Design SW 238 mm Sidewall Protector 4 mm Rim Size 6.75 × 17.5 Max. Load at 60 km/h 3250 kg Carcass Steel Cord Type 3 + 9 + 15*0.175 + 0.15NT Tensile Strength 1720 N Cord EPD 60 Bead Number of Windings 58 Configuration Hexagonal 7- . . . -10- . . . -7 Tensile Strength 3900 N Belt Belt Layer #1 (innermost) #2 (third-outermost) Belt Width 160 mm 180 mm Steel Cord Type 3*0.20 + 6*0.35HT 3*0.20 + 6*0.35HT Tensile Strength 1870 N 1870 N Cord EPD 60 60 Angle 24° 15° Belt Layer #3 (second-outermost) #4 (outermost) Belt Width 100 mm 29 mm Steel Cord Type 5*0.30HI 3 + 7*0.20HE Tensile Strength 1875 N 1360 N Cord EPD 40 NA Angle 15°  0°

TABLE-US-00003 TABLE 3 specific example 3 according to the invention General Parameters Construction Radial/Tubeless Design Pressure 10 bar Design OD 735 mm Design SH 145 mm Design SW 238 mm Sidewall Protector 4 mm Rim Size 6.75 × 17.5 Max. Load at 60 km/h 3280 kg Carcass Steel Cord Type 3 + 9 + 15*0.175 + 0.15NT Tensile Strength 1720 N Cord EPD 60 Bead Number of Windings 58 Configuration Hexagonal 7- . . . -10- . . . -7 Tensile Strength 3900 N Belt Belt Layer #1 (innermost) #2 (third-outermost) Belt Width 160 mm 180 mm Steel Cord Type 3*0.20 + 6*0.35HT 3*0.20 + 6*0.35HT Tensile Strength 1870 N 1870 N Cord EPD 60 60 Angle 24° 15° Belt Layer #3 (second-outermost) #4 (outermost) Belt Width 100 mm 29 mm Steel Cord Type 5*0.30HI 3 + 7*0.20HE Tensile Strength 1875 N 1360 N Cord EPD 40 NA Angle 15°  0°

TABLE-US-00004 TABLE 4 specific example 4 according to the invention General Parameters Construction Radial/Tubeless Design Pressure 10 bar Design SW 215 mm Design OD 712 mm Design SH 134 mm Sidewall Protector 4 mm Rim Size 6.00 × 17.5 Max. Load at 60 km/h 2750 kg Carcass Steel Cord Type 3 + 9 + 15*0.175 + 0.15NT Tensile Strength 1720 N Cord EPD 60 Bead Number of Windings 58 Configuration Hexagonal 7- . . . -10- . . . -7 Tensile Strength 3900 N Belt Belt Layer #1 (innermost) #2 (third-outermost) Belt Width 145 mm 160 mm Steel Cord Type 3*0.20 + 6*0.35HT 3*0.20 + 6*0.35HT Tensile Strength 1870 N 1870 N Cord EPD 60 60 Anole 24° 15° Belt Layer #3 (second-outermost) #4 (outermost) Belt Width 100 mm 20 mm Steel Cord Type 5*0.30HI 3 + 7*0.20HE Tensile Strength 1875 N 1360 N Cord EPD 40 NA Anole 15°  0°