JP5275656B2 - Pneumatic tire - Google Patents

Description

  The present invention comprises a plurality of layers of belts on the outer periphery of a crown portion of a toroidal carcass moored to a pair of bead cores, and such belts are inclined with respect to a tire equatorial plane disposed immediately above the carcass. Two layers of inclined belt layers made of rubber-coated steel cords, which are arranged on the outer side in the tire radial direction of the inclined belt layer, and the inclined belt layer has a larger distance in the tire width direction than the distance in the tire width direction of the inclined belt layer. The two large inclined belt layers made of rubber-coated steel cords that extend at an angle with respect to the tire equator surface than the cord to be corded, and the large inclined belt layer are arranged on the tire radial direction outer side, It includes two or more protective belt layers made of rubber-coated steel cords extending at an angle to the belt, such that the cords are tapped between adjacent layers. It relates pneumatic tire according to intersect across the Ya equatorial plane, to improve the durability of the belt of such a pneumatic tire.

  Pneumatic tires, especially pneumatic tires applied to heavy-duty vehicles such as trucks, buses, construction vehicles, etc., need to support a considerable weight and have multiple layers of belts to bear high load loads. .

  For example, in the pneumatic tires described in Patent Documents 1 and 2, the belt has two inclined belt layers made of rubber-coated steel cords that are inclined and extend with respect to the tire equatorial plane disposed immediately above the carcass, and inclined. It is disposed outside the belt layer in the tire radial direction, has a tire width direction distance larger than the tire width direction distance of the inclined belt layer, and extends at a larger angle than the cord constituting the inclined belt layer at a larger angle with respect to the tire equatorial plane. Two large inclined belt layers made of rubber-coated steel cords, and made of rubber-coated, highly extensible steel cords that are arranged on the outer side in the tire radial direction of the large inclined belt layers and extend inclined with respect to the tire equatorial plane Includes two or more protective belt layers. The inclined belt layer has a small inclination angle of the steel cord, so it can bear the tension in the tire circumferential direction, suppresses the tread diameter growth during rolling of the tire load, etc., and maintains the tire shape. ing. The large inclined belt layer is constituted by a cord that is inclined with respect to the tire equatorial plane than the inclined belt layer. In addition, the protective belt layer uses a cord that has an easy-to-extend characteristic, so that the protective belt layer can be deformed due to input from the protrusion when a stone or other protrusion is stepped on when rolling the tire. While following and deforming, it is possible to sufficiently secure stress against such deformation, so that excessive deformation of the large inclined belt layer is suppressed, and the cord of the large inclined belt layer is broken due to excessive deformation. -Damage is prevented and tire durability is improved. In general, the smaller the angle of inclination of the cord constituting the belt layer with respect to the tire equatorial plane, and the greater the distance in the tire width direction of the belt layer, the greater the shear strain during tire load rolling. In particular, separation between the end of the belt in the tire width direction where the strain is concentrated and the rubber in the vicinity thereof easily occurs, and the durability of the tire decreases. In addition, in the belt having a laminated structure, the cords cross between some or all adjacent layers across the tire equatorial plane, and therefore input when stepping on a protrusion such as a stone ( Hereinafter, the belt breakage due to the cut input) is suppressed, and the cut resistance is improved.

JP 2001-301420 A JP 2002-362109 A

  Although the pneumatic tires described in Patent Documents 1 and 2 improve the durability of the tire by disposing a plurality of belt layers, the separation between the end of the belt in the tire width direction and the rubber in the vicinity thereof. Therefore, there is a demand for further improving the durability of the tire by satisfying both the suppression of the above and the improvement of the cut resistance of the belt.

  Therefore, the present invention is an air in which the durability of the tire is further improved by satisfying both the suppression of the separation between the end of the belt in the tire width direction and the rubber in the vicinity thereof and the improvement of the cut resistance of the belt. An object is to provide a tire entering.

In order to achieve the above object, a pneumatic tire according to the present invention includes a plurality of layers of belts on the outer periphery of a crown portion of a toroidal carcass moored to a pair of bead cores, and the belt is disposed immediately above the carcass. Two inclined belt layers composed of rubber-coated steel cords extending obliquely with respect to the tire equator plane, which are arranged on the outer side in the tire radial direction of the inclined belt layer, and the tire is more than the tire width direction distance of the inclined belt layer Two large inclined belt layers made of rubber-coated steel cords, which have a smaller distance in the width direction and extend at an angle with respect to the tire equatorial plane than the cords constituting the inclined belt layers, and tires with large inclined belt layers Including two or more protective belt layers made of rubber-coated steel cords arranged radially outward and extending obliquely with respect to the tire equatorial plane; Belt is code adjacent layers becomes intersect across the tire equatorial plane, the cord diameter of such inclined belt layer, Ri range near 65 to 95% of the cord diameter of the large slant belt layer, inclined belt The breaking strength of the layer treat is characterized by being in the range of 60 to 110% of the breaking strength of the treat of the large inclined belt layer. The cord diameter of the inclined belt layer is more preferably in the range of 70 to 85% of the cord diameter of the large inclined belt layer. In such a configuration, the cord diameter of the inclined belt layer is 65% or more of the cord diameter of the large inclined belt layer, and is larger than the cord diameter of the conventional inclined belt layer. Even if there is an input from the road surface due to stones or the like that is effectively secured, the cord breakage and damage are suppressed, and the durability of the inclined belt layer can be improved. Further, since the cord diameter of the inclined belt layer is 95% or less of the cord diameter of the large inclined belt layer, the cord diameter of the inclined belt layer does not become too large, and therefore the inclined belt layer due to the cord diameter becoming too large. Separation between the end in the tire width direction and the rubber in the vicinity thereof can be suppressed. From these facts, it is possible to further improve the durability of the tire by satisfying both the suppression of the separation between the end of the belt in the tire width direction and the rubber in the vicinity thereof and the improvement of the durability of the belt. The “distance in the tire width direction of the inclined belt layer” herein refers to a distance measured along the tire width direction between both ends of the inclined belt layer in the tire width direction. The “width direction distance” means a distance measured along the tire width direction between both ends of the large inclined belt layer in the tire width direction. The breaking strength of the inclined belt layer treat is in the range of 60 to 110% of the breaking strength of the large inclined belt layer treat. The “breaking strength” as used herein refers to the number of cords to be driven (injection density) within a range of 50 mm in the direction perpendicular to the extending direction of the cord in the treat plane, and one cord after vulcanization molding. This means a value expressed by a value multiplied by the tension (tensile strength) required when the cord is pulled and broken in the axial direction.

Further, the breaking strength of the inclined belt layer is preferably in the range of 60 to 90% of the breaking strength of the large inclined belt layer.

  Furthermore, the cord constituting the inclined belt layer is preferably inclined within a range of 4 to 10 °, more preferably within a range of 4 to 7 ° with respect to the tire equatorial plane.

  Furthermore, the distance in the tire width direction of the inclined belt layer is preferably in the range of 25 to 45% of the tire cross-sectional width, and more preferably in the range of 30 to 40%.

  In addition, the cord constituting the large inclined belt layer is preferably inclined within a range of 18 to 35 ° with respect to the tire equatorial plane.

  In addition, the distance in the tire width direction of the large inclined belt layer is preferably in the range of 55 to 72% of the tire cross-sectional width, and more preferably in the range of 60 to 72%.

  According to the present invention, the pneumatic tire further improves the durability of the tire by achieving both the suppression of separation between the end of the belt in the tire width direction and the rubber in the vicinity thereof and the improvement of the cut resistance of the belt. Tires can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway perspective view of a typical pneumatic tire (hereinafter referred to as “tire”) according to the present invention, and FIG. 2 is a partial cross-sectional view of the tread half of the tire shown in FIG. FIG. 3 is a partial cross-sectional view of the tread half of another pneumatic tire according to the present invention.

  A tire 1 shown in FIGS. 1 and 2 includes a pair of bead portions 3 in which bead cores 2 are embedded, a pair of side wall portions 4 extending outward from the bead portion 3 in the tire radial direction, and spanning between both side wall portions 4 and 4. And a tread portion 5 extending in the direction. Further, the tire 1 includes a toroidal steel carcass 6 moored to the bead core 2 and a belt 7 disposed on the outer side in the tire radial direction of the crown portion of the steel carcass 6.

The tire according to the present invention includes a belt 7 composed of a plurality of layers. The belt 7 is composed of two protective belt layers 8, two large inclined belt layers 9, and two inclined belt layers in this order from the outer side in the tire radial direction. 10 are stacked and arranged. The protective belt layer 8 is made of a rubber-coated high-stretch steel cord that extends with an inclination to the tire equatorial plane CL. The high elongation steel cord refers to a steel cord having high extensibility and an elongation to break of 5 to 8% or more of the total elongation. The large inclined belt layer 9 is arranged on the inner side in the tire radial direction of the protective belt layer 8 and is made of a rubber-coated high-tensile steel cord extending inclined with respect to the tire equatorial plane CL. The high tensile steel cord refers to a steel cord having a tensile strength of 1200 N / mm ² which is mechanical strength, for example. The inclined belt layer 10 is disposed on the inner side in the tire radial direction of the large inclined belt layer 9, and the tire width direction distance W <b> 1 is smaller than the tire width direction distance W <b> 2 of the large inclined belt layer 9. It consists of a rubber-coated high-tensile steel cord that extends at a small angle with respect to the tire equatorial plane CL. As described above, the protective belt layer 8 suppresses excessive deformation of the large inclined belt layer 9 due to input from the road surface when a protrusion or the like is stepped on, and the cord of the large inclined belt layer 9 is broken due to the deformation. -Prevent damage and improve the durability of the tire 1. In addition, the large inclined belt layer 9 resists input from the road surface when a stone or other protrusion is stepped on during rolling of the tire load, so that the destruction of the tire 1 due to such input is suppressed, and the durability of the tire 1 is increased. To improve. Furthermore, the protective belt layer 8 uses a high-stretch steel cord to suppress deformation of the large inclined belt layer 9 when a stone or other protrusion is stepped on when rolling the tire load. Damage is prevented and the durability of the belt 7 is improved. Furthermore, the tire width direction distance W1 of the inclined belt layer 10 is made smaller than the tire width direction distance W2 of the large inclined belt layer 9 to reduce the shear strain generated during rolling of the tire load, thereby reducing the inclination belt layer. The durability of the tire 1 is improved by suppressing the separation between the tire width direction end 11 and the rubber in the vicinity thereof. Further, in the belt 7 having a laminated structure, the cords intersect with each other with the tire equatorial plane CL sandwiched between adjacent layers, and therefore, from various directions when a step such as a stone is stepped on. The destruction of the tire 1 due to input is suppressed, and the durability of the tire 1 is improved. In addition, the number of layers of the protective belt layer 8 can be further increased according to the desired performance. For example, as shown in FIG.

  In the tire 1 of the present invention, the cord diameter of the inclined belt layer 10 is in the range of 65 to 95% of the cord diameter of the large inclined belt layer 9. The cord diameter of the inclined belt layer 10 is more preferably in the range of 70 to 90% of the cord diameter of the large inclined belt layer 9. This is because when the cord diameter of the inclined belt layer 10 is less than 65% of the cord diameter of the large inclined belt layer 9, the inclination of the inclined belt layer 10 is insufficient, and input from the road surface due to stones or the like. This is because the cord is easily broken and damaged, and the durability of the inclined belt layer 10 is lowered. On the other hand, when the cord diameter of the inclined belt layer 10 exceeds 95% of the cord diameter of the large inclined belt layer 9, the cord diameter of the inclined belt layer 10 becomes too large, and the end of the inclined belt layer 10 in the tire width direction is increased. This is because separation between the rubber 11 and the rubber in the vicinity thereof is likely to occur. Therefore, by setting the cord diameter of the inclined belt layer 10 within a range of 65 to 95% of the cord diameter of the large inclined belt layer 9, the tire width direction end 11 of the inclined belt layer 10 and the vicinity thereof are set. It is possible to further improve the durability of the tire 1 by satisfying both the suppression of separation from a certain rubber and the improvement of the durability of the inclined belt layer 10.

  Further, the breaking strength of the treat of the inclined belt layer 10 is preferably in the range of 60 to 110%, more preferably in the range of 60 to 90% of the breaking strength of the treat of the large inclined belt layer 9. Because, when the breaking strength of the treat of the inclined belt layer 10 is less than 60% of the breaking strength of the treat of the large inclined belt layer 9, Even if the cord of the large inclined belt layer 9 is not broken / damaged due to the input, the breaking strength of the treat of the inclined belt layer 10 is insufficient, and the cord of the inclined belt layer 10 may be broken / damaged. is there. On the other hand, if the breaking strength of the treat of the inclined belt layer 10 exceeds 110% of the breaking strength of the treat of the large inclined belt layer 9, the breaking strength of the treat of the inclined belt layer 10 becomes too large, and therefore The cord breakage / damage of the inclined belt layer 10 due to the input from the protrusions during movement can be effectively suppressed, but when the inclined belt layer 10 undergoes shear deformation, the inclined belt layer 10 has an end 11 in the tire width direction. This is because the stress is concentrated excessively, so that the separation between the tire width direction end 11 of the inclined belt layer 10 and the rubber in the vicinity thereof may occur, and the durability of the tire may be reduced.

  Furthermore, the cords constituting the inclined belt layer 10 are preferably inclined with respect to the tire equatorial plane CL within a range of 4 to 10 °, more preferably within a range of 4 to 7 °. . Because, when the cord constituting the inclined belt layer 10 is inclined at less than 4 ° with respect to the tire equator plane CL, the inclination angle of the cord with respect to the tire equator plane CL becomes too small. Can sufficiently bear the tension in the tire circumferential direction and suppress the diameter growth of the tread portion 5 to maintain the tire shape, but the shear strain at the time of tire load rolling becomes too large, and the inclined belt Since stress is excessively concentrated on the tire width direction end 11 of the layer 10, separation between the tire width direction end 11 of the inclined belt layer 10 and rubber in the vicinity thereof may occur, and the durability of the tire 1 may be reduced. Because there is sex. On the other hand, when the cords constituting the inclined belt layer 10 are inclined more than 10 ° with respect to the tire equator plane CL, the inclination angle of the cord with respect to the tire equator plane CL becomes too large. This is because the layer 10 cannot sufficiently bear the tension in the tire circumferential direction, and the tread portion 5 may grow excessively in diameter, and the tire shape may not be maintained.

  Furthermore, the tire width direction distance W1 of the inclined belt layer 10 is preferably in the range of 25 to 45% of the tire cross-sectional width W3, and more preferably in the range of 30 to 40%. This is because when the tire width direction distance W1 of the inclined belt layer 10 is less than 25% of the tire cross-sectional width W3, the region where the inclined belt layer 10 is disposed becomes too small, and the tension in the tire circumferential direction is reduced. This is because there is a possibility that the tire shape cannot be maintained because the tread portion region in which the diameter growth of the tread portion 5 cannot be suppressed becomes too large. On the other hand, when the tire width direction distance W1 of the inclined belt layer 10 exceeds 45% of the tire cross-sectional width W3, the shear strain of the inclined belt layer 10 at the time of tire load rolling becomes too large, and the inclined belt layer 10 Since the stress is excessively concentrated on the tire width direction end 11 of the tire, peeling of the inclined belt layer 10 from the tire width direction end 11 and the rubber in the vicinity thereof may occur, which may reduce the durability of the tire. It is.

  In addition, the cord constituting the large inclined belt layer 9 is preferably inclined within a range of 18 to 35 ° with respect to the tire equator plane CL. This is because when the cord constituting the large inclined belt layer 9 is inclined at an angle of less than 18 ° with respect to the tire equator plane CL, the inclination angle of the cord with respect to the tire equator plane CL becomes too small. The stress load at the time of rolling is transferred to the inclined belt layer 10, and stress is excessively concentrated on the end 11 in the tire width direction of the inclined belt layer 10. This is because there is a possibility that the performance may be lowered. On the other hand, when the cord constituting the large inclined belt layer is inclined at an angle exceeding 35 ° with respect to the tire equatorial plane CL, the stress load at the time of tire load rolling is transferred to the inclined belt layer 10, and the inclined belt This is because when the stress is excessively concentrated on the tire width direction end 11 of the layer 10, peeling from the rubber in the vicinity thereof may occur, and the durability of the tire 1 may be reduced.

  In addition, the tire width direction distance W2 of the large inclined belt layer 9 is preferably in the range of 55 to 72%, more preferably in the range of 60 to 72% of the tire cross-sectional width W3. This is because, when the tire width direction distance W2 of the large inclined belt layer 9 is less than 55% of the tire cross-sectional width W3, the arrangement range of the large inclined belt layer 9 becomes too small. When the stress load is transferred to the inclined belt layer 10 and the stress is excessively concentrated on the end 11 in the tire width direction of the inclined belt layer 10, peeling from the rubber in the vicinity thereof occurs, and the durability of the tire 1 is reduced. Because there is a possibility. On the other hand, when the distance W2 in the tire width direction of the large inclined belt layer 9 exceeds 72% of the tire cross-sectional width W3, the input from the protrusion when a protrusion such as a stone is stepped on at the time of tire load rolling Although it can resist effectively, since the shear strain of the large inclined belt layer 9 becomes too large, peeling from the rubber in the vicinity thereof may occur, and the durability of the tire 1 may be reduced. is there.

  The above description shows only a part of the embodiment of the present invention, and these configurations can be combined alternately or various changes can be made without departing from the gist of the present invention. For example, in the illustrated example, the cords constituting the various belt layers use linearly extending cords, but they may be cords extending in a wavy or zigzag manner.

  Next, tires having conventional belts (conventional tires 1 to 2) and tires having belts according to the present invention (example tires 1 to 6) are respectively prototyped as heavy duty tires having a tire size of 53 / 80R63. Since the performance evaluation was performed, it will be described below.

  Example tires 1 to 6 are belts composed of two inclined belt layers, two large inclined belt layers whose distance in the tire width direction is larger than the distance in the tire width direction of the inclined belt layer, and two protective belt layers. In such a belt, the cords cross between the adjacent layers with the tire equatorial plane in between. The cord diameter of the inclined belt layer is in the range of 65 to 95% of the cord diameter of the large inclined belt layer. Conventional tires 1-2 have basically the same configuration as the example tires except that the cord diameter of the inclined belt layer is not in the range of 65 to 95% of the cord diameter of the large inclined belt layer. . Table 1 shows the specifications of these tires. In addition, the breaking strength of the treat obtained from the cord diameter, the tensile strength of the cord (A), the cord driving density (B), and the product of (A) and (B) is indexed in the large inclined belt layer. Each is converted into 100, and each is shown as a relative value compared with those in the inclined belt layer.

  Each of these test tires was attached to a rim having a size of 36.00 × 5.0 to form a tire wheel, which was subjected to the following various evaluations regarding tire durability.

  The durability of the inclined belt layer when running straight on a flat road surface is determined by the tire wheels to which air pressure: 900 kPa (relative pressure) is applied, placed on a drum testing machine having a drum diameter of 7 m, and The Tire And Rim Association. , Inc. (TRA) “Year Book” based on 150% load: 1223.8 kN It was evaluated by examining over 240 hours whether or not a change in the shape of the tread portion due to the separation with the rubber in the vicinity occurred. In addition, when the change in tread part shape did not generate | occur | produce after 240 hours, it indexed as 100, and time to the change in the case of changing in less than 240 hours in other tires was calculated and evaluated as a relative value. In addition, it represents that it is excellent in durability, so that a numerical value with 100 as an upper limit is excellent, and the tire whose numerical value is 85 or more (equivalent to 204 hours or more) has fully improved durability on a flat road surface, and is marketable. It was determined that there was. The numerical value is more preferably 90 or more. The results are shown in Table 2.

  Durability (cut resistance) of the inclined belt layer when running straight on an uneven road surface is such that those tire wheels to which air pressure: 900 kPa (relative pressure) is applied are arranged on a drum with a semicircular projection having a radius of 20 cm. Under the condition that 100% load based on TRA “YEAR BOOK”: 815.9 kN is loaded on a drum testing machine having a drum diameter of 7 m so that the entire road contact area of the tire is in contact. Traveling speed: By rotating the tire wheel at a rotational speed corresponding to 8 km / h, it is investigated over 240 hours whether the tread part shape change caused by the break (cut) of the inclined belt layer is caused by the photographing device. evaluated. In addition, when the change in tread part shape did not generate | occur | produce after 240 hours, it indexed as 100, and time to the change in the case of changing in less than 240 hours in other tires was calculated and evaluated as a relative value. In addition, it represents that it is excellent in durability, so that a numerical value with 100 as an upper limit is excellent, and the numerical value of 85 or more (equivalent to 204 hours or more) fully improves the durability at the time of straight running on a rough road surface. It was judged that there was marketability. The numerical value is more preferably 90 or more. The results are shown in Table 2.

  As is clear from the results in Table 2, in the conventional tires 1 and 2, only one of the durability of the inclined belt layer on a flat road surface and the durability of the inclined belt layer on an uneven road surface is improved. On the other hand, in the tires 1 to 6, both the durability of the inclined belt layer on a flat road surface and the durability of the inclined belt layer on an uneven road surface are effectively improved, and the durability of the tire is improved. It was. In particular, in the example tires 3 to 5, both durability were improved.

  As is clear from the above, the durability of the tire is further improved by achieving both the suppression of separation between the end of the belt in the tire width direction and the rubber in the vicinity thereof and the improvement of the cut resistance of the belt. It became possible to provide a pneumatic tire.

1 is a partially broken perspective view of a typical tire according to the present invention. It is sectional drawing which shows a part of tread half part of the tire shown in FIG. It is sectional drawing which shows a part of tread half part of the other tire according to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire 2 Bead core 3 Bead part 4 Side wall part 5 Tread part 6 Steel carcass 7 Belt 8 Protective belt layer 9 Large inclined belt layer 10 Inclined belt layer 11 Tire width direction end CL of inclined belt layer Tire equatorial plane W1 Inclined belt layer Tire width direction distance W2 Tire width direction distance W3 of large inclined belt layer Tire cross-sectional width

Claims (6)

A rubber coating comprising a plurality of layers of belts on the outer periphery of a crown portion of a toroidal carcass moored to a pair of bead cores, the belt extending obliquely with respect to a tire equatorial plane disposed immediately above the carcass The two inclined belt layers made of the steel cords are arranged on the outer side in the tire radial direction of the inclined belt layer, and the distance in the tire width direction is larger than the distance in the tire width direction of the inclined belt layer to constitute the inclined belt layer bilayer large slant belt layer formed of steel cords and rubber coated extending obliquely at a large angle with respect to the tire equatorial plane than code, and disposed in the tire radial direction outer side of the large slant belt layer, said tire comprises two or more layers of the protective belt layer made of steel cords rubberized coating extending obliquely with respect to the equatorial plane, said belt cord in adjacent layers the A pneumatic tire comprising crossing across the ear equatorial plane,
Cord diameter of the inclined belt layer, Ri range near 65 to 95% of the cord diameter of the large inclination belt layer,
The pneumatic tire according to claim 1, wherein a break strength of the inclined belt layer treat is in a range of 60 to 110% of a break strength of the large inclined belt layer treat. 2. The pneumatic tire according to claim 1, wherein a break strength of the inclined belt layer treat is in a range of 60 to 90% of a break strength of the large inclined belt layer treat. The pneumatic tire according to claim 1 or 2, wherein the cord constituting the inclined belt layer is inclined with respect to the tire equatorial plane within a range of 4 to 10 °.   The pneumatic tire according to any one of claims 1 to 3, wherein a distance in the tire width direction of the inclined belt layer is in a range of 25 to 45% of a tire cross-sectional width. The pneumatic tire according to any one of claims 1 to 4, wherein the cord constituting the large inclined belt layer is inclined with respect to the tire equatorial plane within a range of 18 to 35 °.   The pneumatic tire according to any one of claims 1 to 5, wherein a distance in the tire width direction of the large inclined belt layer is within a range of 55 to 72% of a tire cross-sectional width.

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