JP6668784B2 - Pneumatic bias tire - Google Patents

Description

  The present invention relates to a pneumatic bias tire.

  In a pneumatic bias tire having a plurality of carcass layers, the angle of the carcass cord changes during tire production, and the number of carcass cord ends increases in the shoulder portion due to the effect of the lift. The carcass cords may be rubbed during running and mechanical separation may occur.

  Until now, such problems have been dealt with by reducing the number of carcass ends or making the carcass cords thinner, but there is a drawback that tire strength is reduced, and durability performance tends to be reduced. is there.

  By the way, conventionally, for example, Patent Document 1 discloses a pneumatic tubeless tire in which the cord of the carcass layer of the innermost ply adjacent to the inner liner among a plurality of carcass layers has a smaller diameter than the cords of other plies. Have been.

  Conventionally, for example, in Patent Document 2, a belt layer and a tread portion are sequentially provided on the tire radial outside of a crown portion of a carcass layer formed of one or more carcass plies, and the belt layer is formed of a single wire or A spiral formed by winding a belt-shaped rubber-coated cord layer formed by embedding a plurality of parallel cords in a coating rubber so as to form a cord angle within a range of 0 to 5 degrees with respect to the tire circumferential direction. 1 shows a motorcycle pneumatic tire having at least one belt layer. When the tread surface distance from the tire center to the tread edge is L, this spiral pneumatic tire has a spiral belt only within a range of 0.65L to 0.85L along the tread surface from the tire center. The spiral belt layer includes a center-side spiral belt member that straddles the tire center, and a pair of shoulder-side spiral belt members disposed on the tread shoulder sides on both sides in the tire width direction. Adjacent ends of the member and the shoulder-side spiral belt member are separated at intervals within a range of 0.1 L to 0.42 L along the tread surface, from the tire center to the end of the center-side spiral belt member. The distance along the tread surface is within the range of 0.08L to 0.25L There, the distance along the tread surface from the tire center to the edge of the tire center side of the shoulder-side spiral belt member is in the range of 0.25L～0.5L.

  Conventionally, for example, Patent Document 3 discloses that a pair of sidewall portions connected to each bead portion and a toroidal shape are formed on both sidewall portions over one or more bead cores embedded in the pair of bead portions. There is shown a high-speed heavy-load pneumatic tire provided with a carcass comprising a plurality of plies for reinforcing a continuous tread portion. This high-speed heavy-load pneumatic bias tire has a carcass, between at least a pair of adjacent plies, the number of cords in the carcass ply on the outer side in the tire radial direction is sparse, the number of cords in the inner carcass ply is dense, and these An auxiliary rubber layer having a higher vulcanization speed than that of the cord coating rubber of the inner carcass ply is provided between the carcass plies having different driving numbers.

Conventionally, for example, Patent Literature 4 discloses a carcass of a steel cord in a radial direction array including bead cores on both sides and including both bead cores and both ends being folded around the bead cores, and a carcass outside the crown portion. It has a belt layer consisting of a plurality of plies in which cords are arranged substantially parallel to the tire equator, and the cords of this belt layer are made of a material having an elastic modulus of 10 ⁵ kg / cm ² or more, Further, a high internal pressure radial tire is characterized in that the cord of the belt layer is embedded more densely at the center of the belt than at the end of the belt.

JP-A-62-279103 JP 2009-51363 A JP 2001-158207 A JP-A-61-75002

  The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic bias tire capable of improving durability performance.

  In order to solve the above-described problems and achieve the object, in the pneumatic bias tire of the present invention, a plurality of carcass layers having a carcass cord inclined with respect to the tire circumferential direction cross each other's carcass cords. A pneumatic bias tire to be arranged, wherein at least one carcass layer includes a main carcass cord whose both ends reach a bead portion and a short carcass cord having a shorter length than the main carcass cord. The short carcass cord is arranged at a predetermined interval together with the main carcass cord in a tread center portion, and the end number of the carcass cord in the tread shoulder portion is smaller than the end number of the carcass cord in the tread center portion. I do.

  According to this pneumatic bias tire, since the number of carcass cord ends in the tread shoulder portion can be reduced, it is possible to prevent a situation in which the number of carcass cord ends in the tread shoulder portion increases during tire production. Moreover, according to the pneumatic bias tire, the number of ends of the carcass cord in the tread center portion can be increased by the short carcass cord, so that a decrease in tire strength can be prevented. As a result, the durability performance can be improved.

  Further, in the pneumatic bias tire of the present invention, for the carcass layer on which the short carcass cords are arranged, the number of carcass cords at the tread center portion including the short carcass cords is 35 [50/50 mm] or more and 55 [lines]. / 50 mm] or less, the end number of the carcass cord of the tread shoulder portion is 20 [lines / 50 mm] or more and 45 [lines / 50 mm] or less, and the tread shoulder portion is less dense than the tread center portion. .

  According to this pneumatic bias tire, the end number of the carcass cord in the tread shoulder portion is in the range of 20 [lines / 50 mm] or more and 45 [lines / 50 mm] or less, so that the carcass cords in the tread shoulder portion during tire manufacture are manufactured. The effect of preventing a situation in which the number of ends increases is remarkably obtained. In addition, by setting the number of ends of the carcass cord in the tread center portion in the range of 35 [lines / 50 mm] to 55 [lines / 50 mm], the effect of preventing a decrease in tire strength can be remarkably obtained. As a result, the durability performance can be further improved.

  In the pneumatic bias tire of the present invention, the carcass layer on which the short carcass cords are arranged has an angle of 20 ° or more and 60 ° or less with respect to the tire circumferential direction at a tread center portion including the short carcass cords. It is characterized by being in the range.

  According to this pneumatic bias tire, in a bias tire in which the angle of the carcass cord with respect to the tire circumferential direction at the tread center portion is not less than 20 ° and not more than 60 °, an increase in the number of carcass cord ends in the tread shoulder portion during tire production is suppressed. can do. As a result, the durability performance can be further improved.

  In the pneumatic bias tire of the present invention, the short carcass cords are arranged in a range of 30% or more and 85% or less of a tread width around the tire equatorial plane with respect to the carcass layer on which the short carcass cords are arranged. It is characterized by that.

  According to this pneumatic bias tire, by arranging the short carcass cords in a range of 30% or more and 85% or less of the tread width around the tire equatorial plane, the effect of preventing a decrease in tire strength can be remarkably obtained. . In addition, since the short carcass cords are not arranged in the remaining range of the tread width, the effect of preventing an increase in the number of carcass cord ends in the tread shoulder portion during tire production can be significantly obtained. As a result, the durability performance can be further improved.

  According to the present invention, durability performance can be improved.

FIG. 1 is a meridional sectional view of a pneumatic bias tire according to an embodiment of the present invention. FIG. 2 is a development view of a carcass layer of the pneumatic bias tire according to the embodiment of the present invention. FIG. 3 is a meridional sectional view of another example of the pneumatic bias tire according to the embodiment of the present invention. FIG. 4 is a development view of a carcass layer of another example of the pneumatic bias tire according to the embodiment of the present invention. FIG. 5 is a table showing the results of performance tests of the pneumatic bias tire according to the example of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the embodiment. The components of this embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Further, the plurality of modified examples described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a meridional sectional view of the pneumatic bias tire according to the present embodiment. FIG. 2 is a development view of a carcass layer of the pneumatic bias tire according to the present embodiment.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic bias tire 1, and the tire radial direction inner side is the side toward the rotation axis in the tire radial direction, the tire radial direction. The outer side refers to a side apart from the rotation axis in the tire radial direction. The tire circumferential direction refers to a circumferential direction with the rotation axis as a central axis. Further, the tire width direction refers to a direction parallel to the rotation axis, the inside in the tire width direction refers to the side toward the tire equatorial plane (tire equator line) CL in the tire width direction, and the outside in the tire width direction refers to the tire width direction. Means the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane perpendicular to the rotation axis of the pneumatic bias tire 1 and passing through the center of the tire width of the pneumatic bias tire 1. The tire width is a width in the tire width direction between portions located outside in the tire width direction, that is, a distance between portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic bias tire 1. In the present embodiment, the same reference numeral “CL” is given to the tire equator line as the tire equatorial plane.

  As shown in FIG. 1, the pneumatic bias tire 1 of the present embodiment includes a tread 2, side portions 3 on both sides of the tread 2, and a bead portion 4 inside each side portion 3 in the tire radial direction. I have. The pneumatic bias tire 1 has a carcass layer 5.

  The tread 2 is made of a rubber material, and is exposed on the outermost side in the tire radial direction of the pneumatic bias tire 1, and its surface becomes the contour of the pneumatic bias tire 1. A tread surface 2A is formed on the outer peripheral surface of the tread 2, that is, on a tread surface that comes into contact with a road surface during traveling.

  Although not explicitly shown in the figure, the tread surface 2A may be provided with a circumferential groove extending along the tire circumferential direction. A plurality of circumferential grooves may be provided in parallel in the tire width direction. When having a circumferential groove, the tread surface 2A is formed with a plurality of rib-shaped land portions extending along the tire circumferential direction by the circumferential groove. Further, the tread surface 2A may be provided with a lateral groove extending in a direction intersecting with the tire circumferential direction, though not explicitly shown in the figure. A plurality of lateral grooves are arranged in the tire circumferential direction. The lateral groove has a form in which an end communicates with the circumferential groove and a form in which the lateral groove does not communicate.

  The side portion 3 is a portion having a continuous rubber material on both sides of the tread 2 in the tire width direction and exposed to the outermost in the tire width direction of the pneumatic bias tire 1. The bead portion 4 is a portion that has a rubber material continuous inside the side portion 3 in the tire radial direction and is engaged with the rim. Bead part 4 has bead core 4A and bead filler 4B. The bead core 4A is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 4B is a rubber material disposed in a space formed by folding the end portion of the carcass layer 5 in the tire width direction at the position of the bead core 4A.

  The carcass layer 5 is configured such that each end in the tire width direction is folded back from the inside in the tire width direction to the outside in the tire width direction by a pair of bead cores 4A, and is wound around in the tire circumferential direction in a toroidal shape to form a tire skeleton. It is. As shown in FIG. 2, the carcass layer 5 is formed by coating a plurality of carcass cords 5A arranged in parallel in the tire circumferential direction at a certain angle with respect to the tire circumferential direction. Further, at least two carcass layers 5 are provided and arranged so as to cross each other's carcass cords 5A to form a bias structure. In the present embodiment, four carcass layers 5 are provided.

  The pneumatic bias tire 1 of the present embodiment is configured as a tubed tire in which a tube is arranged inside the carcass layer 5, although not explicitly shown in the drawing. The tube is filled with air. Further, the pneumatic bias tire 1 of the present embodiment may be configured as a tubeless tire in which no tube is arranged. In the case of a tubeless tire, although not shown in the drawing, an inner liner layer is provided on the tire inner surface, which is the inner peripheral surface of the carcass layer 5, to suppress the permeation of air molecules to the tire outside. Air is filled inside the inner liner layer.

  The pneumatic bias tire 1 described above has a ground contact area on the tread surface 2A of the tread 2 in a meridional section in a state where the rim is assembled to a regular rim and filled with a regular internal pressure. The contact area is such that when the pneumatic bias tire 1 is rim-assembled to a regular rim, filled with a regular internal pressure and subjected to 70% of a regular load, the tread surface 2A of the tread 2 of the pneumatic bias tire 1 is brought into contact with the road surface. This is the area to be grounded. The regular rim is a "standard rim" defined by JATMA, a "Design Rim" defined by TRA, or a "Measuring Rim" defined by ETRTO. The normal internal pressure is the "maximum air pressure" specified by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO. The normal load is the “maximum load capacity” specified by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or the “LOAD CAPACITY” specified by ETRTO.

  In the pneumatic bias tire 1 of the present embodiment, as shown in FIG. 1, both ends of the ground contact region are defined as tread shoulder portions TSh, and the position of the tire equatorial plane CL is defined as a tread center portion TCe.

  Then, in the pneumatic bias tire 1 of the present embodiment, as shown in FIG. 2, the carcass layer 5 includes a carcass cord 5A, a main carcass cord 5Aa having both ends reaching the bead portion 4, and a main carcass cord 5Aa. Also includes a short carcass cord 5Ab having a short length. The short carcass cords 5Ab are arranged at predetermined intervals in the tread center TCe together with the main carcass cords 5Aa, and are not arranged in the tread shoulder TSh. In the carcass layer 5, as shown in FIG. 2, in a state where one carcass layer 5 is developed, a short carcass cord 5Ab is arranged only at a center portion on the tire equatorial plane CL in the entire tire width direction. Can be obtained at

  Here, in the pneumatic bias tire 1, the fact that the short carcass cord 5Ab is arranged in the tread center portion TCe means that the pneumatic bias tire 1 is assembled on a regular rim and filled with a regular internal pressure in a no-load state. At this time, it is assumed that the short carcass cord 5Ab exists at a portion where a normal line (corresponding to the tire equatorial plane CL in the present embodiment) drawn from the tread center portion TCe to the tire outermost carcass layer 5 intersects. means. Further, in the carcass layer 5, the phrase “not arranged in the tread shoulder portion TSh” means that the pneumatic bias tire 1 is rim-assembled into a regular rim, and the tire is moved from the tread shoulder portion TSh in a no-load state where the regular internal pressure is filled. This means that the short carcass cord 5Ab does not exist at a portion where a normal line (indicated by a dashed line in FIG. 1) drawn to the radially outermost carcass layer 5 intersects.

  Thus, depending on the presence or absence of the short carcass cord 5Ab, the number of ends of the carcass code 5A of the tread shoulder TSh becomes smaller than the number of ends of the carcass code 5A of the tread center TCe including the short carcass code 5Ab.

  Here, in the present embodiment, the end number of the carcass cord 5A is set such that the carcass cord per 50 mm in the tire circumferential direction is in a no-load state in which the pneumatic bias tire 1 is assembled on a regular rim and filled with a regular internal pressure. The number is 5 A, and the unit is [number / 50 mm].

  According to the pneumatic bias tire 1, since the number of ends of the carcass cord 5A in the tread shoulder portion TSh can be reduced, it is possible to prevent a situation in which the number of ends of the carcass cord 5A in the tread shoulder portion TSh increases during tire production. In addition, according to the pneumatic bias tire 1, the number of ends of the carcass cord 5A of the tread center TCe can be increased by the short carcass cord 5Ab, so that a decrease in tire strength can be prevented. As a result, the durability performance can be improved.

  Note that the carcass layer 5 having the short carcass cord 5Ab is preferably applied to all the carcass layers 5 in order to remarkably obtain the above effects, but the above effect is obtained even when applied to at least one carcass layer 5. be able to. In addition, when the carcass layer 5 having the short carcass cord 5Ab is applied to a carcass layer 5 arranged on the outer side in the tire radial direction, the above effect can be remarkably obtained.

  Further, in the pneumatic bias tire 1 of the present embodiment, for the carcass layer 5 on which the short carcass cords 5Ab are arranged, the end number of the carcass cords 5A of the tread center TCe including the short carcass cords 5Ab is 35 [/ 50 mm]. Not less than 55 [lines / 50 mm], the number of ends of the carcass cord 5A of the tread shoulder portion TSh is not less than 20 [lines / 50 mm] and not more than 45 [lines / 50 mm], and the tread shoulder portion TSh is greater than the tread center portion TCe. Preferably, it is sparse.

  According to the pneumatic bias tire 1, by setting the number of ends of the carcass cord 5A of the tread shoulder portion TSh to be in the range of 20 [lines / 50 mm] to 45 [lines / 50 mm], the tread shoulder portion TSh during tire manufacturing. The effect of preventing the situation where the number of ends of the carcass cord 5A is increased can be remarkably obtained. Further, by setting the number of ends of the carcass cord 5A of the tread center TCe in the range of 35 [lines / 50 mm] to 55 [lines / 50 mm], the effect of preventing a decrease in tire strength can be remarkably obtained. As a result, the durability performance can be further improved.

  In the pneumatic bias tire 1 of the present embodiment, the carcass layer 5 on which the short carcass cords 5Ab are arranged has an angle of 20 ° with respect to the tire circumferential direction at the tread center TCe including the short carcass cords 5Ab. It is preferable that the angle be in the range of at least 60 °.

  When the angle of the carcass cord 5A with respect to the tire circumferential direction at the tread center TCe is less than 20 °, the carcass cord 5A becomes close to the tire circumferential direction, and the strength as a bias tire tends to decrease. On the other hand, if the angle of the carcass cord 5A with respect to the tire circumferential direction at the tread center TCe exceeds 60 °, the carcass cord 5A approaches the radial direction, and the strength as a bias tire tends to decrease. Therefore, according to the pneumatic bias tire 1, in a bias tire in which the angle of the carcass cord 5A with respect to the tire circumferential direction at the tread center TCe is not less than 20 ° and not more than 60 °, the carcass cord 5A in the tread shoulder portion TSh during tire production. Can be suppressed from increasing. As a result, the durability performance can be further improved.

  In the pneumatic bias tire 1 of the present embodiment, with respect to the carcass layer 5 on which the short carcass cords 5Ab are arranged, the short carcass cords 5Ab are not less than 30% and not more than 85% of the tread width W around the tire equatorial plane CL. It is preferable to be arranged in a range.

  Here, the tread width W is a dimension between the tread shoulder portions TSh when the pneumatic bias tire 1 is rim-assembled to a normal rim and is filled with a normal internal pressure in a no-load state. When the short carcass cord 5Ab is arranged in a range WCe of 30% or more and 85% or less of the tread width W around the tire equatorial plane CL, the tread center portion TCe is included in the range WCe, and the remaining tread width W is included. The range WSh includes the tread shoulder portion TSh.

  According to the pneumatic bias tire 1, by arranging the short carcass cords 5Ab in the range WCE not less than 30% and not more than 85% of the tread width W around the tire equatorial plane CL, the effect of preventing a decrease in tire strength is remarkable. Can be obtained. Further, since the short carcass cord 5Ab is not arranged in the remaining range WSh of the tread width W, the effect of preventing the end number of the carcass cord 5A from increasing in the tread shoulder portion TSh during tire production can be significantly obtained. . As a result, the durability performance can be further improved.

  FIG. 3 is a meridional sectional view of another example of the pneumatic bias tire according to the present embodiment. FIG. 4 is a development view of a carcass layer of another example of the pneumatic bias tire according to the present embodiment.

  The pneumatic bias tire 1 shown in FIG. 3 and the carcass layer 5 shown in FIG. 4 are different from the pneumatic bias tire 1 shown in FIG. 1 and the carcass layer 5 shown in FIG. The difference is that short carcass cords 5Ab are also provided at both ends in the direction, and other configurations are the same. Therefore, the same reference numerals are given to the same parts and the description is omitted.

  As described above, by providing the short carcass cords 5Ab also at both ends in the tire width direction of the carcass layer 5 reaching the bead portions 4, a decrease in tire strength at the side portions 3 and the bead portions 4 can be prevented. As a result, the durability performance can be further improved.

  By providing short carcass cords 5Ab at both ends in the tire width direction of the carcass layer 5 reaching the bead portion 4, a preferable range for obtaining the above effect is as shown in FIG. The range SH ′ is 50% or more and 80% or less inside the tire radial direction SH with respect to the tire cross-section height SH when the rim is assembled and the normal internal pressure is filled and there is no load. Note that the tire section height SH is a half of the difference between the tire outer diameter and the rim diameter when the pneumatic bias tire 1 is rim assembled to a regular rim and filled with a regular internal pressure in a no-load state. .

  The pneumatic bias tire 1 of the present embodiment includes various types of bias structures, but is particularly preferably applied to light trucks and industrial vehicles. In pneumatic bias tires used for light trucks and industrial vehicles, the angle of the carcass cord changes during tire manufacturing, and the number of carcass cord ends increases in the shoulder due to the effect of the lift. The distance between the carcass cords may be reduced and mechanical separation may occur due to friction between the carcass cords during traveling. Therefore, a remarkable effect can be obtained by applying the pneumatic bias tire 1 of the present embodiment to a small truck or an industrial vehicle. The pneumatic bias tire applied to light trucks and industrial vehicles has a carcass layer 5 in a range of two or more and eight or less.

  In this example, a performance test on the durability of the carcass layer was performed for a plurality of types of pneumatic bias tires having different conditions (see FIG. 5).

  In this performance test, a pneumatic bias tire (test tire) having a tire size of 5.00-12 12 PR was used. There are four carcass layers.

  The evaluation method is as follows. An indoor drum tester is used, the test tire is filled with a normal internal pressure (550 kPa), a load of 5.74 kN is applied, the speed is set to 120 km / h, and the speed is increased every 5 hours by 5 km / h. The running distance up to is measured. Then, based on the measurement result, an index evaluation is performed using the conventional example as a reference (100). This evaluation indicates that the larger the index, the better the durability performance.

  As shown in FIG. 5, in the conventional pneumatic bias tire, the end numbers of the carcass cords in the tread shoulder portion are denser than the end numbers of the carcass cords in the tread center portion in all the carcass layers. As shown in FIGS. 1 and 2, the pneumatic bias tires of Examples 1 to 16 have a tread shoulder portion that is smaller than the number of carcass cord ends in the tread center portion where the short carcass cords are arranged in all carcass layers. Of carcass cords are sparse. In the pneumatic bias tire of Example 16, short carcass cords were provided at both ends in all carcass layers.

  As shown in the test results of FIG. 5, it can be seen that the pneumatic bias tires of Examples 1 to 16 have improved durability performance.

Reference Signs List 1 pneumatic bias tire 2 tread 2A tread surface 3 side portion 4 bead portion 5 carcass layer 5A carcass cord 5Aa main carcass cord 5Ab short carcass cord CL tire equatorial plane TCe tread center portion TSh tread shoulder portion W tread width

Claims (4)

A pneumatic bias tire in which a plurality of carcass layers having carcass cords inclined with respect to the tire circumferential direction are arranged so as to cross the carcass cords with each other,
For at least one carcass layer, the carcass cord includes a main carcass cord having both ends reaching a bead portion and a short carcass cord having a shorter length than the main carcass cord, and the short carcass cord is arranged in a tread center portion. A pneumatic bias tire arranged at a predetermined interval together with a main carcass cord, wherein the number of ends of the carcass cord of the tread shoulder portion is smaller than the number of ends of the carcass cord of the tread center portion.   Regarding the carcass layer on which the short carcass cords are arranged, the end number of the carcass cords in the tread center portion including the short carcass cords is 35 [lines / 50 mm] or more and 55 [lines / 50 mm] or less, and the tread shoulder portion has 2. The pneumatic bias tire according to claim 1, wherein the end number of the carcass cord is not less than 20 [lines / 50 mm] and not more than 45 [lines / 50 mm], and the tread shoulder portion is sparser than the tread center portion.   The carcass layer in which the short carcass cords are arranged, wherein an angle of the carcass cords with respect to a tire circumferential direction at a tread center portion including the short carcass cords is in a range of 20 ° or more and 60 ° or less. 3. The pneumatic bias tire according to 1 or 2.   4. The carcass layer in which the short carcass cords are arranged, wherein the short carcass cords are arranged in a range from 30% to 85% of a tread width around a tire equatorial plane. 5. The pneumatic bias tire according to any one of the above.

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