JP6245003B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving uneven wear resistance.

  In recent years, especially heavy-duty tires mounted on trucks, buses, etc. have a low flatness ratio, but as a belt layer, the circumferential belt layer is arranged in addition to the cross belt layer to increase the rigidity of the tread portion. Techniques that attempt to maintain the overall shape have been studied. The circumferential belt layer is approximately 0 degrees with respect to the tire circumferential direction (generally, it is “approximately 0 degrees because it is spirally wound) and within a range of ± 5 degrees with respect to the tire circumferential direction. And a belt layer having a belt angle that is stacked on the pair of cross belts. Here, the belt angle is an inclination angle formed by the length direction of the belt cord with respect to the tire circumferential direction.

  As conventional pneumatic tires employing such a configuration, techniques described in Patent Documents 1 to 4 are known.

JP 2006-528105 A JP-T-2006-528102 JP 2006-528103 A Special table 2012-522686 gazette

  In particular, in a heavy-duty pneumatic radial tire with a flatness ratio of 70% or less, in addition to the intersecting belt layer, the configuration including the above-described at least one circumferential belt layer tends to maintain the overall shape. It becomes a pneumatic tire excellent in terms.

  On the other hand, the tire shoulder region tends to be relatively less rigid than the tread region, and as a result, slippage of the shoulder land portion during rolling of the tire increases and uneven wear occurs in the shoulder land portion. In the traction pattern that has a lug groove or sipe in the shoulder portion, it has been found that there is a tendency for baldness (chunking) to occur during braking and driving.

  An object of the present invention is a pneumatic tire having a traction pattern with lug grooves and sipes in the shoulder portion, and has excellent uneven wear resistance and excellent chunking resistance, and both these characteristics are compatible. It is to provide a pneumatic tire that can be used.

  The pneumatic tire of the present invention that achieves the above-described object has the following configuration (1).

(1) A carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and at least three extending in the tire circumferential direction A pneumatic tire having a circumferential main groove of a book and a plurality of land portions divided into the circumferential main grooves, wherein the belt layer has a belt angle of 10 degrees to 45 degrees in absolute value. And a pair of crossed belt layers having belt angles of opposite signs and a circumferential belt layer having a belt angle within a range of ± 5 degrees with respect to the tire circumferential direction, and Among the circumferential main grooves, the left and right circumferential main grooves on the outermost side in the tire width direction are called outermost circumferential main grooves, and the land portion on the outer side in the tire width direction than the left and right outermost circumferential main grooves is a shoulder. With land Beauty, a land portion on the inner side in the tire width direction than the outermost direction main grooves of the left and right when calling the center rib, in a cross-sectional view of a tire meridian direction,
(A) The ground contact surface of the center rib is a curve that protrudes outward in the tire radial direction,
(B) The ground contact surface of the shoulder land portion has a curved line L1 that protrudes outward in the tire radial direction disposed on the inner side in the tire width direction of the contact surface, and a tire radial inner side that is disposed on the outer side in the tire width direction. Consisting of the curve L2,
(C) In the shoulder land portion, the region radially outside the virtual line L3 connecting the bottoms of the at least three circumferential main grooves, and the tire width direction of the boundary point P between the curves L1 and L2 In the outer region, a shoulder protective layer formed of rubber having a larger elongation at break than the rubber in the land is configured.
A pneumatic tire characterized by that.

In the pneumatic tire according to the present invention, preferably, the pneumatic tire has any one of the following configurations (2) to (6).
(2) The distance Gcc from the tread profile to the tire inner circumferential surface on the tire equator plane and the distance Gsh from the tread end to the tire inner circumferential surface have a relationship of Gsh / Gcc ≧ 1.1. The pneumatic tire according to (1) above.
(3) The distance Dcc between the groove bottom line on the tire equatorial plane and the circumferential belt layer, and the distance De between the groove bottom line and the circumferential belt layer at the end of the circumferential belt satisfy De / Dcc ≦ 1.0. The pneumatic tire according to (1) or (2), wherein the pneumatic tire has a relationship.
(4) The pneumatic tire according to any one of (1) to (3), wherein a thickness of the shoulder protective layer in a tire width direction is 1 to 4 mm.
(5) The pneumatic tire according to any one of (1) to (4), wherein a sipe is provided on a side side surface of the shoulder land portion.
(6) The pneumatic tire according to any one of (1) to (5), wherein the shoulder protective layer is made of the same rubber as that of the sidewall.

  According to the pneumatic tire of the present invention according to claim 1, in the pneumatic tire having a traction pattern having lug grooves and sipes in the shoulder portion, the tire has excellent uneven wear resistance as a whole and excellent in the shoulder portion. A pneumatic tire having high chunking resistance is provided.

  According to the pneumatic tire of this invention concerning any one of Claims 2-6, the pneumatic tire which can exhibit the effect of this invention concerning Claim 1 mentioned above more clearly is provided.

FIG. 1 is a cross-sectional view of a principal part in a tire meridian direction illustrating an embodiment of a pneumatic tire according to the present invention. FIG. 2 is a partially fragmented plan view illustrating the laminated structure of the belt layer 14 of the pneumatic tire depicted in FIG. FIG. 3 is a cross-sectional view of a main part in the tire meridian direction for explaining an embodiment of the pneumatic tire of the present invention. FIG. 4 is a perspective view of a main part in the vicinity of a tire tread portion and a shoulder portion for explaining an embodiment of the pneumatic tire of the present invention.

  Hereinafter, the pneumatic tire of the present invention will be described in more detail with reference to the drawings.

As shown in FIG. 1, the pneumatic tire 1 of the present invention includes a carcass layer 11, a belt layer 14 disposed on the outer side in the tire radial direction of the carcass layer 11, and an outer side in the tire radial direction of the belt layer 14. A pneumatic tire having a tread rubber 15 disposed and having at least three circumferential main grooves 2 extending in the tire circumferential direction and a plurality of land portions 3 defined by the circumferential main grooves. The belt layer 14 has a belt angle of 10 degrees or more and 45 degrees or less in absolute value, and a pair of cross belt layers 142 and 143 having belt angles of different signs, and ± 5 with respect to the tire circumferential direction. A circumferential belt layer 144 having a belt angle within a range of degrees, and the left and right circumferential main grooves at the outermost side in the tire width direction of the circumferential main grooves 2 are the outermost circumferential mains. Call the groove In addition, the land portion located on the outer side in the tire width direction from the left and right outermost circumferential main grooves is referred to as a shoulder land portion 3s, and the land portion located on the inner side in the tire width direction from the left and right outermost circumferential main grooves is defined as the center rib 3c. In the cross-sectional view in the tire meridian direction,
(A) The ground contact surface of the center rib 3c is formed of a curve that protrudes outward in the tire radial direction,
(B) The ground contact surface of the shoulder land portion 3s has a curved line L1 that protrudes outward in the tire radial direction disposed on the tire width direction inner side of the ground contact surface, and a tire radial direction inner side that is disposed on the outer side of the ground contact surface tire width direction. Consists of a convex curve L2,
(C) In the shoulder land portion 3s, a tire width at a region radially outside the imaginary line L3 connecting the groove bottoms of at least three circumferential main grooves 2 and a boundary point P between the curve L1 and the curve L2 The shoulder protective layer 15 formed of rubber having a larger elongation at break than the rubber of the land is formed in the outer region in the direction.
It is characterized by that. In FIG. 1, CL is the equator plane of the tire.

  FIG. 2 is a partially fragmented plan view illustrating the laminated structure of the belt layer 14 of the pneumatic tire illustrated in FIG. 1. In FIG. 2, the thin lines drawn in the belt layers 141 to 145 in the belt layer 14. Schematically shows the arrangement direction of the belt cords of the belt layers 141 to 145. Specifically, the belt layer 14 includes a high-angle belt 141, a pair of cross belts 142 and 143, a belt cover 145, and a circumferential belt layer 144, and is wound around the outer periphery of the carcass layer 11. To be placed.

  The high-angle belt 141 is formed by rolling a plurality of belt cords made of steel or organic fiber material (for example, nylon, polyester, rayon, etc.) with a coat rubber, and generally has an absolute value of 45. The belt angle is not less than 70 degrees and not more than 70 degrees. Further, the high-angle belt 141 is laminated and disposed on the outer side in the tire radial direction of the carcass layer 11.

  Each of the pair of cross belts 142 and 143 is formed by rolling a plurality of belt cords made of steel or organic fiber material coated with a coat rubber, and generally has a belt angle of preferably 10 degrees or more and 45 degrees or less. Have. Further, the pair of cross belts 142 and 143 have mutually different signs (plus or minus) belt angles, and are laminated so that the length directions of the belt cords cross each other (cross-ply structure). Note that three or more cross belts may be laminated and arranged. Further, in the illustrated example, the pair of cross belts 142 and 143 are illustrated as being stacked on the outer side in the tire radial direction of the high-angle belt 141, but the stacked structure is not particularly limited, and a high angle The belt 141 may not be disposed.

  The circumferential belt layer 144 is typically configured by winding a steel belt cord coated with a coat rubber in a spiral manner while inclining within a range of ± 5 degrees with respect to the tire circumferential direction. In the illustrated embodiment, the circumferential belt layer 144 is interposed between the pair of cross belts 142 and 143, but is not limited to this configuration. Further, the circumferential belt layer 144 is arranged such that the edge is located on the inner side in the tire width direction than the left and right edge portions of the pair of cross belts 142 and 143. Specifically, one or a plurality of wires are spirally wound around the outer circumference of the cross belt 142 on the inner diameter side to form the circumferential belt layer 144. The circumferential belt layer 144 is disposed in the center region of the tread portion and exhibits a tagging effect, thereby improving the tire circumferential performance and the radial rigidity, thereby improving the durability of the tire.

  The belt cover 145 is typically formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and a belt having a node value of 10 degrees to 45 degrees. Have an angle. The belt cover 145 is laminated and disposed outside the pair of cross belts 142 and 143 in the tire radial direction. In the illustrated form, the belt cover 145 has substantially the same belt angle as that of the cross belt 143 on the outer diameter side, and is disposed on the outermost layer of the belt layer 14.

  The belt layer 14 may have an edge cover (not shown). The edge covers are respectively arranged on the outer sides in the tire radial direction of the left and right edges of the outer diameter side cross belt 143 (or the inner diameter side cross belt 142). These edges exhibit the so-called tagging effect, so that the difference in radial growth between the center region of the tread portion and the shoulder region is alleviated, and in combination with the tagging effect provided by the circumferential belt layer 144, the tire This significantly improves the uneven wear resistance.

In the pneumatic tire of the present invention, in addition to the above-described configuration, in the sectional view in the tire meridian direction shown in FIG.
(A) The ground contact surface of the center rib 3c is formed from a curve that protrudes outward in the tire radial direction,
(B) The ground contact surface of the shoulder land portion 3s has a curved line L1 that protrudes outward in the tire radial direction disposed on the tire width direction inner side of the ground contact surface, and a tire radial direction inner side that is disposed on the outer side of the ground contact surface tire width direction. Formed from a convex curve L2,
further,
(C) In the shoulder land portion 3s, a tire width at a region radially outside the imaginary line L3 connecting the groove bottoms of at least three circumferential main grooves 2 and a boundary point P between the curve L1 and the curve L2 The shoulder protective layer 15 formed of rubber having a larger elongation at break than the land rubber is formed in a region outside in the direction.

  As described above, the circumferential belt layer 144 is disposed in the center region of the tread portion, thereby exerting a tagging effect and improving the rigidity in the tire circumferential direction and the rigidity in the radial direction, thereby improving the durability of the tire. Performance is improved. On the other hand, the tire shoulder region tends to be relatively less rigid than the tread region, and as a result, slippage of the shoulder land portion during rolling of the tire increases and uneven wear occurs in the shoulder land portion. In the traction pattern that has a lug groove or sipe in the shoulder portion, a problem that baldness (chunking) is likely to occur at the time of braking and driving is likely to occur, but in the pneumatic tire of the present invention, By adopting the configurations (a) to (c) above, the shoulder land, especially the side side rigidity, is increased to suppress uneven wear of the shoulder land and the occurrence of baldness (chunking) during braking and driving. It was possible.

  The rubber of the shoulder protective layer 15 is important for obtaining the effect remarkably to be formed using a rubber having a larger elongation at break than the rubber of the land portion.In particular, according to the knowledge of the present inventors, It is preferable that the land rubber is formed of rubber having a breaking elongation of 400 to 500%, and the shoulder protective layer 15 is formed of rubber having a breaking elongation of 530% or more.

  Further, according to the knowledge of the present inventors, the degree of the so-called “bounce-up” form of the shoulder protective layer 15 formed from the curves L1 and L2 is, as shown in FIG. 3, a tread profile on the tire equatorial plane. It is preferable that the distance Gcc from the tire inner peripheral surface and the distance Gsh from the tread end to the tire inner peripheral surface have a relationship of Gsh / Gcc ≧ 1.1. This is because if the value of Gsh / Gcc is less than 1.1, it is difficult to obtain the effect of the present invention. The upper limit of Gsh / Gcc is 1.3 or less according to the knowledge of the present inventors. Preferably, even if it is larger than 1.3, it becomes difficult to obtain an effect commensurate with it.

  Similarly, as shown in FIG. 3, according to the knowledge of the present inventors, the distance Dcc between the groove bottom line L3 and the circumferential belt layer 144 on the tire equatorial plane, and the end position of the circumferential belt 144 It is preferable that the distance De between the groove bottom line L3 and the circumferential belt layer 144 has a relationship of De / Dcc ≦ 1.0. If the value of De / Dcc is larger than 1.0, the effect of using the circumferential belt layer is reduced, which is not preferable. The lower limit of the value of De / Dcc is up to about 0.8 in order to obtain a good grounding profile with a good balance.

  Further, the thickness of the shoulder protective layer 15 in the tire width direction is preferably 1 to 4 mm in order to clearly obtain the effect of providing the protective layer. The “thickness in the tire width direction” means that, as shown in the shoulder protective layer 15 on the left side of FIG. It refers to the thickness at the position where it intersects the outer edge line (thickness in the direction perpendicular to the line forming the shoulder land portion 3s).

  Further, the pneumatic tire of the present invention is not limited to the present invention in the tire in which the sipe 16 is provided on the side side surface of the shoulder land portion 3 as shown in FIG. It is preferable to configure.

  Further, although not particularly limited, the shoulder protective layer 15 is preferably formed of the same rubber as that constituting the sidewall, and the shoulder protective layer 15 having a small problem of resistance to peeling at the rubber interface is realized. be able to. In that case, it is more effective if the tire is molded so that the rubber constituting the sidewall extends to the inner side in the tire radial direction of the side surface of the shoulder land portion 3.

  The pneumatic tire of the present invention is not particularly limited, but it is more effective if it is configured as a heavy-duty pneumatic radial tire having a flatness ratio of 70% or less and 40% or more. Heavy duty pneumatic radial tires have a greater load when using tires than tires for passenger cars, etc., and the effect of using a circumferential belt layer is remarkable, but there is no circumferential belt layer A heavy-duty pneumatic radial tire can be realized with excellent uneven wear resistance in the shoulder land area.

  A pneumatic tire with a tire size of 265 / 60R22.5, mounted on a rim with a rim size of 22.5 inches x 8.25 inches, filled with JATMA standard maximum air pressure (900 kPa), and a 2-D vehicle drive shaft The actual vehicle running test and evaluation were performed with the maximum load (26.72 kN) of JATMA standard applied.

  In the test tire, the tread groove is as shown in FIG. 1, and the side wall of the shoulder land portion has a sipe as shown in FIG. Comparative Example 1 is a conventional example in which a conventional shoulder protective layer is not formed. In Comparative Example 2 and Comparative Example 3, the shoulder protective layer is provided, but the magnitude relationship between the elongation at break of each rubber constituting the shoulder protective layer and the land portion does not satisfy the present invention. Examples 1-4 change the value of the breaking elongation of rubber | gum of a shoulder protective layer, thickness, and a structure.

The evaluation was performed on the following items after traveling 10,000 km.
In any case, the comparative example 1 (conventional example) was set to 100, and the evaluation was performed using an index indicating that the larger the value, the better.
(A) Chunking resistance The number of cracks and baldness of rubber having a length of 3 mm or more in the shoulder part to the buttress part was counted.
(B) Buttress-resistant crack resistance The number of cracks having a length of 3 mm or more in the buttress part was counted.
(C) Single-drop wear resistance The single-chip wear amount of the rib at the shoulder portion was measured by laser profile measurement.

  Table 1 shows the results of the tests and evaluations described above for each example and comparative example.

1: Pneumatic tire 2: Circumferential main groove 3: Land portion 3c: Center rib 3s: Shoulder land portion 11: Carcass layer 14: Belt layer 141: High angle belt 142: Cross belt layer 143: Cross belt layer 144: Circumference Direction belt layer 145: belt cover 15: tread rubber 16: sipe CL: tire equator

Claims (6)

A carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and at least three circumferences extending in the tire circumferential direction A pneumatic tire having a directional main groove and a plurality of land portions defined by the circumferential main grooves, wherein the belt layer has a belt angle of 10 degrees to 45 degrees in absolute value. A pair of intersecting belt layers having belt angles with different signs from each other and a circumferential belt layer having a belt angle within a range of ± 5 degrees with respect to the tire circumferential direction are laminated, and the circumferential main The left and right circumferential main grooves on the outermost side in the tire width direction among the grooves are referred to as outermost circumferential main grooves, and the land portion on the outer side in the tire width direction from the left and right outermost circumferential main grooves is referred to as a shoulder land portion. Call The land portion in the inner side in the tire width direction than the outermost direction main grooves of the left and right when calling the center rib, in a cross-sectional view of a tire meridian direction,
(A) The ground contact surface of the center rib is a curve that protrudes outward in the tire radial direction,
(B) The ground contact surface of the shoulder land portion has a curved line L1 that protrudes outward in the tire radial direction disposed on the inner side in the tire width direction of the contact surface, and a tire radial inner side that is disposed on the outer side in the tire width direction. Consisting of the curve L2,
(C) In the shoulder land portion, the region radially outside the virtual line L3 connecting the bottoms of the at least three circumferential main grooves, and the tire width direction of the boundary point P between the curves L1 and L2 In the outer region, a shoulder protective layer formed of rubber having a larger elongation at break than the rubber in the land is configured.
A pneumatic tire characterized by that.   The distance Gcc from the tread profile to the tire inner peripheral surface on the tire equatorial plane and the distance Gsh from the tread end to the tire inner peripheral surface have a relationship of Gsh / Gcc ≧ 1.1. The described pneumatic tire.   The distance Dcc between the groove bottom line on the tire equatorial plane and the circumferential belt layer and the distance De between the groove bottom line and the circumferential belt layer at the end of the circumferential belt have a relationship of De / Dcc ≦ 1.0. The pneumatic tire according to claim 1 or 2, characterized in that.   The pneumatic tire according to any one of claims 1 to 3, wherein a thickness of the shoulder protective layer in a tire width direction is 1 to 4 mm.   The pneumatic tire according to any one of claims 1 to 4, wherein a sipe is provided on a side side surface of the shoulder land portion.   The pneumatic tire according to claim 1, wherein the shoulder protective layer is made of the same rubber as that of the sidewall.

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