Patent Application
20240424834
The present invention is directed to a tire comprising a low angle belt. In particular, the tire can be a truck tire. Furthermore, the present invention is directed to a method of building such tires.
Modern truck tires are supposed to meet many different performance requirements such as low rolling resistance and/or high abrasion resistance. It is also desirable that such tires are robust. In particular, forces in the area of the grooves and/or shoulders of the tires shall be reduced. For instance, it is possible to reduce such forces by the provision of respective tread constructions. While progress has been made over the past decades in the development of robust tires, such as robust truck tires, significant room for improvement remains.
In a first aspect of the present invention, the invention is directed to a tire comprising a tread and a belt portion located radially below the tread, wherein the tread has two shoulder portions, and wherein each shoulder portion comprises a shoulder groove. The belt portion comprises a pair of working belts and a low angle belt, wherein the low angle belt has reinforcement elements having an angle of less than 5° with a circumferential direction of the tire. The low angle belt comprises a first layer and one or more further layers, wherein the first layer extends over at least 70% of the axial width of the axially largest working belt. Each layer of the one or more further layers of the low angle belt extends over at most 50% of the axial width of the axially largest working belt and is arranged radially below one of the shoulder grooves.
In a second aspect of the present invention, the invention is directed to a tire comprising a tread and a belt portion located radially below the tread, wherein the belt portion comprises a pair of working belts and a low angle belt comprising at least one ply strip. The ply strip has parallel reinforcement elements having an angle of less than 5° with a circumferential direction of the tire. The pair of working belts comprises a first working belt and a second working belt, wherein each working belt of the pair of working belts comprises parallel reinforcement elements, and wherein the reinforcement elements of the first working belt and the reinforcement elements of the second working belt cross each other at an opposing angle. Still in accordance with the second aspect of the present invention, the difference between i) the absolute value of the angle with the circumferential direction of the reinforcement elements of the first working belt and ii) the absolute value of the angle with the circumferential direction of the reinforcement elements of the second working belt is at least 2°.
In a third aspect of the present invention, the invention is directed to a tire comprising a tread and a belt portion located radially below the tread, wherein the tread has a first shoulder portion on a first lateral side of the tire and a second shoulder portion on a second lateral side of the tire, which is opposite to the first side. The belt portion comprises a pair of working belts and a low angle belt, wherein the low angle belt comprises at least one helically wound ply strip comprising at least one elongated reinforcement element having an angle of less than 5° with a circumferential direction of the tire. Furthermore, the low angle belt comprises a first layer, a second layer and a third layer, formed by said at least one helically wound ply strip. The first layer extends over at least 70% of the axial width of the axially largest working belt, and the second layer is arranged radially below the first layer and below the first shoulder portion. The third layer is arranged radially above the first layer and below the second shoulder portion, and each of the second layer and the third layer extends over at most 50% of the axial width of the axially largest working belt.
In a fourth aspect of the present invention, the invention is directed to a method of building a tire having a tread with two shoulder portions, each shoulder portion optionally having a circumferential shoulder groove, wherein the method comprises the steps of: Providing at least one carcass ply; applying a first working belt onto the at least one carcass ply; and applying a low angle belt onto the first working belt, including steps a) to c):
The invention will be described by way of example and with reference to the accompanying drawings in which:
In the first aspect, the present invention is directed to a tire comprising a tread and a belt portion located radially below the tread, wherein the tread has two shoulder portions, each shoulder portion comprising a, preferably circumferentially extending, shoulder groove. The belt portion comprises a pair of working belts and a low angle belt, wherein the low angle belt has reinforcement elements having an angle of less than 5° (preferably less than 2° or 1°) with a circumferential direction of the tire. The low angle belt comprises a first layer and one or more further layers, wherein the first layer extends over at least 70% (preferably, over at least 75%, and/or less than 95%) of the axial width of the axially largest working belt. Each layer of the one or more further layers of the low angle belt extends over at most 50% (preferably at most 30%, and/or preferably over at least 5%) of the axial width of the axially largest working belt and is arranged radially below one of the shoulder grooves.
Such a construction of the tire having a pair of working belts and a low angle belt, particularly comprising a layer provided radially below a shoulder groove, has been found to improve robustness of the tire, especially in the shoulder area of the tread and/or belt portion. In particular, such a multilayer design of the low angle belt helps to improve durability of the low angle belt, and particularly of its reinforcements, in a shoulder area of the tire.
In one embodiment, the low angle belt comprises at least one ply strip. The ply strip is preferably a wound ply strip. It can be considered as wound (e.g., spirally/helically wound) about an axial direction of the tire, e.g., to form at least one layer of the low angle belt. The strip may be wound at an angle of less than 5° with the circumferential direction of the tire. Preferably, such an angle is between 0.1° and 4°, or between 0.1° and 2°, or even more preferably between 0.2° and 1°. This angle is preferably the same angle as the angle of the parallel and/or elongated reinforcement elements of the ply strip. The reinforcement elements of the ply strip are preferably coated with a (coating) rubber composition so as to form the ply strip. In other words, the ply strip comprises reinforcement elements coated by a rubber composition.
In another embodiment, each of the one or more further layers (e.g., a second layer and/or a third layer) extends over an axial width corresponding to 5% to 30% (preferably 5% to 20%) of the axial width of the axially largest working belt. Alternatively, or in addition, each of the one or more further layers (e.g., a second layer and/or a third layer) extends over an axial width corresponding to a range of 90% to 300% (preferably, of 100% or 110% to 250%) of the axial width of the (radially outer or outermost) opening of a respective shoulder groove located radially above the respective further layer of the low angle belt.
In another embodiment, the one or more further layers comprise a second layer arranged radially below a first shoulder groove, and a third layer arranged radially below a second shoulder groove. Preferably, the low angle belt comprises only these three layers.
In another embodiment, the tread comprises four circumferential grooves, including two shoulder grooves, wherein one of the shoulder grooves is located at each axially/laterally outer side of the tread.
In still another embodiment, the axially largest working belt (which is preferably the radially inner working belt) extends over an axial width which is within a range of 110% to 200%, preferably from 115% to 160%, of the axial distance between the axially (and radially) outer edges of the shoulder grooves. An axially (and radially) outer edge of a shoulder groove can also be described as an axially outer edge of a radially outer opening of such a groove.
In another embodiment, each of the first layer, the second layer, and the third layer are formed by at least one ply strip comprising the reinforcement elements. It is possible that each layer is formed by one or more separate ply strips. Optionally, each strip is wound and/or constructed as mentioned herein above.
In another embodiment, the first layer, the second layer and the third layer are formed by the same ply strip. For instance, it is possible that the second layer is helically wound about a radially lower working belt from an axially inner position towards a first axially outer position. From the first axially outer position the strip is wound radially on top of the second layer in an axially inner direction so as to form the first layer, covering at least 70% of the axial width of the axially largest working belt. From a second axially outer (or outermost) position (e.g., on an opposite axial/lateral side of the tire) of the first layer, the axial winding direction of the strip is reversed so as to provide the third layer on top of the first layer. Providing all three layers with one strip is particularly fast and cost efficient. Also, different tire widths and diameters can be built with such a method, e.g., by using only a single strip type.
In another embodiment, one or more of the first layer, the second layer, and the third layer are each formed by at least one separate ply strip.
In still another embodiment, the second layer is located radially below the first layer and the third layer is located radially above the first layer. Such a preferred construction is easy to manufacture in one strip winding step.
In still another embodiment, both of the second layer and the third layer are located either radially below the first layer or radially above the first layer. It is also possible that the second layer and the third layer are provided at essentially the same radial height. However, each of the second layer and the third layer preferably forms a circumferential band radially below each shoulder groove or shoulder of the tire. A position radially below each shoulder groove or shoulder of the tire does not exclude that one or more further belts are provided radially above the second and/or third layer between the second and/or third layer and the shoulder groove.
In still another embodiment, the low angle belt (including its layers) is provided radially between the two working belts of the pair of working belts.
In still another embodiment, the ply strip has an axial width within a range of 1.5 mm to 25 mm (preferably from 3 mm to 16 mm, or from 3 mm to 9 mm), and/or a radial thickness within a range of 0.5 mm to 3 mm, (preferably from 1 mm to 3 mm). Such radial thickness values may also apply to other belts or belt plies mentioned herein, including one or more of working belts, transition belts and top belts.
In still another embodiment, the ply strip comprises from 1, preferably from 2 to 5 parallel reinforcement elements selected from one or more of cords and wires.
In still another embodiment, the ply strip has a density of parallel reinforcement elements ranging from 10 EPI to 20 EPI.
In still another embodiment, the working belts have a density of parallel reinforcement elements ranging from 8 EPI to 15 EPI, preferably from 10 EPI to 14 EPI.
In still another embodiment, the said reinforcement elements are one or more of: elongated reinforcement elements; metal reinforcement elements; metal and/or hybrid cords, optionally comprising multiple metal wires/filaments. A preferred metal herein is steel. Metal reinforcement elements may optionally be coated with brass. In a most preferred embodiment, the reinforcement elements are brass-coated steel cords, particularly comprising multiple steel wires.
In still another embodiment, the reinforcement elements (e.g., of the working belts and/or the low angle belts) are metal cords having a construction a+b×d, wherein a is ranging from 2 to 5 (metal wires/filaments), b is ranging from 2 to 4 (metal wires/filaments) and d (the respective diameter of the metal wires/filaments) is ranging from 0.2 mm to 0.5 mm (preferably from 0.3 mm to 0.45 mm. In particular such a construction is considered to be relatively open for rubber penetration which further improves robustness of the tire.
In another embodiment, the cords (e.g., of the working belts and/or the low angle belts, preferably of all of them) have the construction 4+3×0.35. In this examples, four inner filaments (or wires) are straight, and three filaments are twisted over the four inner filaments. Alternatively, the thickness of the single wires/filaments forming the cord is preferably within a range t of 0.15 to 0.35 mm. Accordingly, the metal cord may have the construction 4+3×t, such as with t as mentioned above.
In another embodiment, the reinforcement elements or cords have an elongation at 10% of their breaking force which is higher than 0.2% or 0.21%, and preferably lower than 0.4%, 0.35%, 0.3%, or 0.29%, measured after extraction from the cured tire. Preferably such values apply to the cords of the working belts and/or the cords of the low angle belt. Cord elongation or tensile tests on the cords are carried out herein for cords extracted out of the cured tire according to ISO 6892-1B, with a preload of 20 MPa.
In still another embodiment, the pair of working belts comprises a first working belt and a second working belt, wherein the low angle belt is arranged between the first working belt and the second working belt, wherein each working belt of the pair of working belts comprises parallel reinforcement elements, and wherein the reinforcement elements of the first working belt and the reinforcement elements of the second working belt cross each other at an opposing angle, or in other words, with an opposite angular orientation.
In still another embodiment, the absolute value of the angle of the (respective) reinforcement elements of each working belt with the circumferential direction ranges from 10° to 50°, preferably from 15° to 30°, or more preferably from 15° to 25°. Alternatively, or in addition, the difference between i) the absolute value of the angle of the reinforcement elements of the first working belt and ii) the absolute value of the angle of the reinforcement elements of the second working belt is at least 2° (preferably at least 3° and/or at most 15°, or at most 8°, or only at most 6°). Preferably, the radially innermost working belt has the larger absolute angle. This is for instance preferred to have this angle closer to an angle of an/the at least one carcass ply, which has preferably an angle of 90° with the circumferential direction. Preferably, the belt portion has no transition belt in such an embodiment between the radially innermost working belt and the adjacent carcass ply, which is provided radially below said innermost working belt.
In still another embodiment, each working belt of the pair of working belts comprises parallel reinforcement elements, wherein at least one of i) the reinforcement elements of the workings belts, and ii) the reinforcement elements of the low angle belt have a relative elongation at 10% of their/the breaking force which is lower than 0.4% (preferably, lower than 0.3%, or lower than 0.29%). Optionally, said elongation is at least 0.2% or 0.21%.
In still another embodiment, the tire further comprises a top belt arranged radially above the low angle belts and the pair of working belts. The top belt preferably comprises parallel reinforcement elements having an angle within a range of 10° to 25°, preferably 14° to 21°, with the circumferential direction of the tire. Optionally, the top belt is axially narrower than each of the workings belts and the first layer of the low angle belt.
In still another embodiment, the top belt comprises a rubber composition reinforced by cords (e.g., metal, textile, or hybrid cords). Preferably, the cords are metal cords. Suitable cord constructions include for example, 3+2×0.35 and/or 5×0.35 and/or 5×0.38.
In still another embodiment, the belt portion has exactly four belts, i.e., the two working belts, the low angle belt (with multiple layers, preferably exactly three layers) and the top belt.
In still another embodiment, the top belt has an axial width of at least 50% of the axial width of the axially largest working belt and/or the radially innermost working belt. In addition, or alternatively, the axial width of the top belt is within a range of 50% to 90% (preferably 60% to 80%) of the axially largest working belt and/or the radially innermost working belt.
In yet another embodiment, the tire further comprises a transition belt arranged radially below the low angle belts and the pair of working belts. Optionally, the transition belt comprises parallel reinforcement elements having an angle within a range of 35° to 90° (preferably of 50° to 90°, or more preferably of 50° to) 75° with the circumferential direction of the tire. Preferably, the transition belt is axially narrower than each of the workings belts and the first layer of the low angle belt.
In still another embodiment, the tire further comprises a rubber ply arranged between the radially inner working belt and the radially outermost carcass ply. Such a rubber ply is preferably devoid of reinforcements. Optionally, it has a radial thickness within a range of 0.5 mm to 3 mm, preferably within a range of 1 mm to 2.5 mm. Preferably, it has a stiffness which is at most the stiffness of the rubber composition of the radially inner working belt. Preferably, such a stiffness of the rubber composition of the rubber ply is at least 5% lower than the stiffness of the rubber composition of the radially inner working belt. Stiffness is determined herein as G′ (1%). G′ is obtained herein at 100° C. and 1 Hz at 1% strain with an RPA 2000™ Rubber Process Analyzer of the company Alpha Technologies, based on ASTM D5289, or equivalent.
In still another embodiment, one or more of the first layer, the second layer, and the third layer (of the low angle belt), do not axially extend beyond an adjacent axially outer edge of the one or more of the working belts.
In still another embodiment, one or more of the first layer, the second layer, and the third layer, extends axially beyond an adjacent axially outer edge of a top belt (if present). Preferably, one or more of the first layer, the second layer, and the third layer extend less than 10%, (preferably less than 5%) of the total axial width of the top belt beyond an axially outer edge of the top belt.
In still another embodiment, the belt portion has one or more of the following: a first layer of the low angle belt which is axially larger than a top belt; a first working belt which is axially larger than the first layer, and a second working belt which is axially larger than the first working belt (and which is preferably provided between the top belt and the low angle belt), wherein the first working belt is preferably provided radially below the top belt, the second working belt, and the layers of the low angle belt.
In another embodiment, each of the belts extends in an axially outer direction so as to support a shoulder groove on each lateral/axial side of the tire. In other words, each belt optionally extends to an outer axial position which is axially outside a radial outermost end of an axially outer sidewall of a respective shoulder groove.
In still another embodiment, at least one of the working belts and/or the low angle belt have a rubber penetration of at least 90%, preferably of at least 95%, even more preferably of at least 99% or 100%. Rubber penetration is measured herein through an air permeability test according to L. BOURGOIS, Survey of Mechanical Properties of Steel Cord and Related Test Methods, Special Technical Publication 694, ASTM, 1980. Such a high rubber penetration provides an even higher durability of the respective belt layers and helps to avoid cord breaking.
According to the second aspect of the present invention, the invention is directed to a tire comprising a tread and a belt portion located radially below the tread, wherein the belt portion comprises a pair of working belts and a low angle belt comprising at least one ply strip. The ply strip has parallel reinforcement elements having an angle of less than 5° with a circumferential direction of the tire. The pair of working belts comprises a first working belt and a second working belt, wherein each working belt of the pair of working belts comprises parallel reinforcement elements, and wherein the reinforcement elements of the first working belt and the reinforcement elements of the second working belt cross each other at an opposing angle, or, in other words, at opposite angular orientation. Furthermore, an absolute value of the angle of the reinforcement elements of each working belt with the circumferential direction ranges from 10° to 50° preferably from 15° to 30°, or 15° to 25°. Still in accordance with the second aspect of the present invention, the difference between i) the absolute value of the angle with the circumferential direction of the reinforcement elements of the first working belt and ii) the absolute value of the angle with the circumferential direction of the reinforcement elements of the second working belt is at least 2° (preferably at least 3° and/or at most 10°, or at most 8°, or only at most 6°).
Such a combination of a low angle belt with a pair of working belts has been found to be particularly desirable to provide a robust belt portion for a tire, such as a truck tire.
Preferably, the low angle belt is provided between the first working belt and the second working belt.
In one embodiment, the absolute value of the angle of a radially inner working belt is from 2° to 10° (preferably from 3° to 8°) larger than the absolute value of the angle of a radially outer working belt. In particular, it has been found by the inventors that such a relatively small difference is of advantage for the durability of the belt portion.
In another embodiment, the tread has two shoulder portions, with each shoulder portion optionally comprising a shoulder groove, and wherein the low angle belt comprises a first layer and one or more further layers. Optionally, the first layer of the low angle belt extends over at least 70% of the axial width of the axially largest working belt. In addition, or alternatively, each layer of the one or more further layers of the low angle belt extends over at most 50%, preferably at most 30%, of the width of the axially largest working belt and/or is arranged radially below one of the shoulder grooves, particularly to support at least the whole axial width of the respective shoulder groove (measured at the radially outermost opening of such a shoulder groove).
In still another embodiment, the reinforcement elements of the workings belts, and/or the reinforcement elements of the low angle belt have a relative elongation at 10% of their/the breaking force which is within a range of 0.2% and 0.29%.
In still another embodiment, one or more, preferably all layers, of the low angle belt are formed by a single ply strip.
In still another embodiment, the tire is one or more of: a pneumatic tire; a radial tire; one of a 17.5, 19.5, 22.5 and a 24.5 inch tire; a truck tire; a tire having at least one steel reinforced carcass ply; a tire comprising steel reinforced working belts and/or a reinforced low angle belt formed by steel reinforced ply strip.
In the third aspect, the invention is directed to a tire comprising a tread and a belt portion located radially below the tread, wherein the tread has a first shoulder portion on a first lateral (or axial) side of the tire and a second shoulder portion on a second lateral (or axial) side of the tire, which is opposite to said first side. The belt portion comprises a pair of working belts and a low angle belt, wherein the low angle belt comprises at least one helically wound ply strip (e.g., helically wound about the axial direction) comprising at least one elongated reinforcement element (such as at least one cord) having an angle of less than 5° with a circumferential direction of the tire. Furthermore, the low angle belt comprises a first layer, a second layer and a third layer, formed by said at least one helically wound ply strip. The first layer extends over at least 70% of the axial width of the axially largest working belt, and the second layer is arranged radially below the first layer and below the first shoulder portion, and optionally below a circumferential shoulder groove of said portion. The third layer is arranged radially above the first layer and below the second shoulder portion, and optionally below a circumferential shoulder groove of said portion, wherein each of the second layer and the third layer extends over at most 50% (preferably at most 30% and/or at least 5% or 10%) of the axial width of the axially largest working belt.
In one embodiment, the second layer and/or the third layer is arranged axially outside a respective shoulder groove of the respective shoulder portion.
It is emphasized herein that embodiments and/or features of the first aspect and/or the second aspect can also be applied to the third aspect.
According to the fourth aspect of the present invention, the present invention is directed to a method of building a tire (such as one of the tires mentioned herein above) having a tread with two shoulder portions, each shoulder portion having preferably a circumferential shoulder groove, wherein the method comprises one or more of the following steps:
The above method provides a very efficient way to provide a low angle belt to increase robustness of the belt portion and the tread, such as to the shoulder portions, particularly the shoulder grooves.
In one embodiment, the first winding step, the second winding step and the third winding step are carried out continuously, e.g., in one pass.
In another embodiment, said winding is helically winding, such as about the axial direction, and/or as described in other passages herein.
It is emphasized that the method of building a tire is not limited to the mentioned steps and that such a method does not exclude further manufacturing or mounting steps of further tire components, e.g., sidewalls, chafers, beads, apexes, overlays, etc. Such steps could also be present between one or more of the above-mentioned steps.
The first working belt 110 and the second working belt 130 have parallel and elongated reinforcements or reinforcement elements, in this case metal cords, which have an angle with the circumferential direction c within a range of 10° to 50°. The reinforcement elements of the first working belt 110 cross the reinforcement elements of the second working belt 130 with opposite angular orientation, wherein that angle of the first working belt 110 with the circumferential direction c is in a preferred embodiment 4° larger than such an angle of the second working belt 130 with the circumferential direction c. As further schematically shown in
The ply strip, or in other words the helically wound ply strip, which forms the layers of the low angle belt 120, has as such a width within a range of 3 mm to 25 mm and a radial thickness within a range of 0.5 mm to 3 mm. In a preferred embodiment of the invention, the strip has 5 mm width and about 2 mm thickness. In another specific embodiment, it has 15 mm width and 2 mm thickness.
The axial direction a, the circumferential direction c and the radial direction r are indicated in
As mentioned above,
In each of the non-limiting embodiments shown in the Figures herein, the low angle belts have elongated reinforcement elements in the form of metal cords, in particular steel cords, which are preferably brass coated. In a preferred example they have the following cord construction: 4+3×0.35. In this example, four inner filaments (or wires) are straight and three filaments are twisted over the four inner filaments which provides a relatively open construction which allows for example a good rubber (coating) penetration.
For instance, the metal or steel cords in the working belts may have one of the following cord constructions: 3×7×0.22; 3×4×0.22; 4×4×0.22; 4+3×0.35; 3+2×0.35 and have an elongation at 10% of their breaking force which is larger than 0.4%, and preferably smaller than 1%. The thickness of a single wire forming such a cord is preferably within a range of 0.15 to 0.35 mm.
However, even more preferred herein are working belts having the same or similar cords as the low angle belt. For instance, those may have the following cord constructions: 4+3×0.35 and/or 3+2×0.35.
The cords may also have constructions selected from: 3+2×0.35; 3+3×0.35; 3+4×0.35; 4+2×0.35; 4+3×0.35; 4+4×0.35; 5+2×0.35; 5+3×0.35; 5+4×0.35; 4×6×0.19; 4×5×0.20; and a+b×d, wherein a is ranging from 3 to 5, b is ranging from 2 to 4 and d is ranging from 0.2 mm to 0.5 mm (preferably from 0.3 mm to 0.45 mm).
An end per inch (EPI) range of cords in the working belts is preferably ranging from 8 to 14 EPI. An end per inch range in the low angle belt ply strips is preferably within a range of 10 EPI to 20 EPI, preferably from 10 EPI to 16 EPI, or more preferably from 14 EPI to 16 EPI. Preferably, an EPI range of the cords in the top belt is from 8 EPI to 14 EPI, preferably less than 10 EPI.
Preferably, the cords utilized herein have an elongation (or relative elongation) at 10% of their breaking force which is larger than 0.2%, preferably smaller than 0.4%.
In relation to the inventive examples of a belt portion 100 shown in
Moreover, the inventors have tested the rubber penetration in the belts, and their layers used in the embodiments herein. The test results show a 100% rubber penetration in the low angle belt, including all of its layers and across the whole axial width. The same applies to each of the working layers. Such a very high rubber penetration makes the tire more robust.
The present invention, and optionally one or more of its embodiments, help to provide robust tires, particularly having an advanced belt portion. For instance, stability of the shoulder and/or groove areas can be improved. Moreover, simple and/or cost-effective manufacturing is possible.
The above first, second, third, and fourth aspects, and/or one or more of their respective embodiments and/or features, may be combined with one another.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 63509153 | Jun 2023 | US |
