JP4540487B2 - Pneumatic tire - Google Patents

Description

    The present invention relates to a pneumatic tire in which a belt reinforcing layer that overlaps a belt layer is disposed in a tread portion.

As conventional pneumatic tires, for example, those described in Patent Document 1 below are known.
JP 2002-46415 A

  This is a carcass layer whose ends in the width direction are folded around a bead core and extend in a toroidal shape, and is arranged radially outside the carcass layer, at the same angle within a range of 15 to 35 degrees with respect to the tire equator. A belt layer composed of two belt plies in which metal wire cords inclined in the opposite direction are embedded, a tread disposed radially outward of the belt layer, and between the belt layer and the tread And a belt reinforcing layer in which a reinforcing cord made of organic fibers extending substantially parallel to the tire equator is embedded.

  And this is a tread of pneumatic tires for high performance passenger cars, aircrafts, trucks, buses, etc. by centrifugal force during high speed running due to the reinforcing cords extending substantially parallel to the tire equator in the belt reinforcing layer It is possible to suppress the large diameter growth of the portion radially outward, thereby reducing heat generation and distortion at the belt end to improve high-speed durability.

    When such a pneumatic tire travels under a load, the tread portion is deformed so as to be flat from an arc shape in the ground contact region, and is radiused from a neutral axis of bending (usually located on the outer belt ply). The inner belt ply located on the inner side in the direction generates a tensile force in the circumferential direction, while the belt reinforcement layer located on the outer side in the radial direction from the neutral axis of the bending generates a compressive force in the circumferential direction. The metal wire cords in the belt ply are inclined at a small angle of 15 to 35 degrees with respect to the tire equator, while the reinforcement cords in the belt reinforcement layer extend substantially parallel to the tire equator. The reinforcement cord is not easily stretched or compressed in the circumferential direction, so that the inner belt ply and the belt reinforcement layer arranged at a distance on both sides of the neutral axis of the bend are resistant to tensile and compressive forces. Acts as a strong resistance.

  As a result, the out-of-plane bending rigidity in the tread portion in the circumferential direction (stiffness against bending with the crease in the tire width direction) is increased, which increases the longitudinal spring constant of the pneumatic tire and reduces ride comfort performance. In addition, there is a problem that the contact length is shortened, the contact area is reduced, and the steering stability is lowered.

  An object of the present invention is to provide a pneumatic tire capable of improving ride comfort and handling stability while maintaining high-speed durability.

Such a purpose is that both ends in the width direction are folded around the bead core and extend in a toroidal shape, and the non-stretching is arranged in the radial direction outside the carcass layer and inclined in the opposite direction with respect to the tire equator S. a belt layer sex of the belt cord is composed of three base Rutopurai embedded therein, a tread disposed radially outward of the belt layer is arranged so as to overlap with the belt layer, substantially on the tire equator S therein A pneumatic tire comprising a belt reinforcement layer in which a non-stretchable reinforcement cord extending in parallel is embedded, and of the belt plies, a belt ply closest to the belt reinforcement layer is a proximity belt ply. When the next adjacent belt ply is the next adjacent belt ply, these adjacent belt plies and belts embedded in the next adjacent belt ply With a large in the order of the inclination angle A with respect to the tire equator S of over de, when the farthest belt ply from the belt reinforcing layer and separation belt ply, tire belt cords embedded in the separation belt in the ply This can be achieved by making the inclination angle A with respect to the equator S the same as the inclination angle A with respect to the tire equator S of the belt cord embedded in the next adjacent belt ply .

  In the present invention, since the inclination angle A of the belt cord embedded in the adjacent belt ply and the next adjacent belt ply with respect to the tire equator S is increased in the above order, the neutral axis (normally bent) when the tread portion is deformed by ground contact. The tensile force or the compressive force generated at a position radially away from the adjacent belt ply) is a next adjacent belt ply in which a belt cord having a relatively large inclination angle with respect to the tire equator is embedded and It acts on the belt reinforcing layer.

Here, since the belt cord of the next adjacent belt ply arranged at a position away from the belt reinforcing layer is inclined at an inclination angle A that is relatively large with respect to the tire equator S, the coating rubber between the belt cords is It becomes extended or compressed by the tensile force or compressive force, and the resistance function against the tensile force or compressive force is lowered. As a result, the out-of-plane bending rigidity in the circumferential direction at the tread portion is reduced, thereby reducing the longitudinal spring constant of the pneumatic tire and improving the riding comfort performance, and increasing the contact length and increasing the contact area. Steering stability is improved . Et al is, it is possible to code the tilt angle to produce a pneumatic tire using the same belt ply, production becomes easy, thereby reducing the cost.

Hereinafter, an example of a pneumatic tire will be described with reference to the drawings.
In FIGS. 1 and 2, reference numeral 11 denotes a pneumatic radial tire for a passenger car that can run at high speed. The pneumatic tire 11 includes a pair of bead portions 13 each having a bead core 12 embedded therein, and a radial direction from the bead portions 13. Side wall portions 14 extending outward are provided, and a substantially cylindrical tread portion 15 that connects the outer ends in the radial direction of the side wall portions 14 is provided. It should be noted, may be applied to the pneumatic tire of or for trucks and buses for the aircraft.

  The pneumatic tire 11 has a carcass layer 18 that extends between the bead cores 12 in a toroidal shape and reinforces the side wall portions 14 and the tread portions 15. Both end portions of the carcass layer 18 in the width direction of the bead core 12 It is turned around from the axially inner side to the axially outer side. The carcass layer 18 is composed of at least one carcass ply 19 in this case, and the carcass ply 19 intersects the tire equator S at a cord angle of 70 to 90 degrees, that is, in a radial direction ( A large number of mutually parallel carcass cords 20 made of nylon, aromatic polyamide, steel, etc. (here, nylon) extending in the meridian direction are embedded.

  23 is a belt layer arranged radially outward of the carcass layer 18, and this belt layer 23 has at least two belt plies, here two belt plies 24, 25 in this order toward the radially outer side. It is configured by stacking. Here, a plurality of parallel non-extensible belt cords 26 and 27 are embedded in the belt plies 24 and 25, respectively, and these belt cords 26 and 27 are stranded wires made of steel, aromatic polyamide or the like. Or it is comprised from the monofilament. The belt cords 26 and 27 in the two belt plies 24 and 25 are inclined in opposite directions with respect to the tire equator S and intersect each other.

  31 is a tread made of rubber disposed radially outward of the carcass layer 18 and the belt layer 23. The outer surface (tread surface) of the tread 31 is wide and continuous in the circumferential direction in order to improve drainage performance. Thus, a plurality of main grooves 32 extending in this case are formed. In addition, a large number of lateral grooves extending in the width direction or oblique direction may be formed on the outer surface of the tread 31.

  Reference numeral 35 denotes a belt reinforcing layer disposed on the tread portion 15 between the belt layer 23 and the tread 31 so as to overlap the belt layer 23. The belt reinforcing layer 35 is at least one (here, one) reinforcing ply. A non-extensible reinforcement cord 37 extending substantially parallel to the tire equator S is embedded in each reinforcement ply 36. If the belt reinforcing layer 35 covering the belt layer 23 is provided on the outer side in the radial direction of the belt layer 23 in this way, the tread portion 15 is strongly prevented from growing greatly in the radial direction due to centrifugal force during high-speed running. Thus, the high-speed durability of the pneumatic tire 11 can be reliably maintained as it is.

Here, the above-described belt reinforcing layer 35 can be formed by, for example, winding a ribbon-like body having a constant width in which one or a small number of reinforcing cords 37 are arranged side by side and covered with rubber spirally around the outside of the belt layer 23. . If the belt reinforcing layer 35 is formed in this way, the belt reinforcing layer 35 can be formed with high efficiency and high accuracy. The reinforcing cord 37 in the belt reinforcing layer 35 may be made of steel, but is preferably made of aromatic polyamide as in this example . The reason for this is that, in this way, the diameter growth of the tread portion 15 can be strongly suppressed even when the tread portion 15 becomes high temperature due to high speed running while achieving weight reduction.

  When the pneumatic tire 11 as described above is run under a load, the tread portion 15 having an arc shape in the tire equator direction is deformed so as to have a flat shape in the ground contact region, and the neutral axis of the bending (usually normal The belt ply 24 located on the inner side in the radial direction (on the belt ply 25) generates a circumferential tensile force. Here, the belt cord 26 in the belt ply 24 is inclined with respect to the tire equator S. When the angle A is small, the belt ply 24 does not easily extend in the direction of the tire equator S and functions as a strong resistance against the ground deformation. In the prior art, since the inclination angle A is often in the range of 20 to 30 degrees in order to increase the in-plane rigidity, it can be a sufficient resistance to the tensile force as described above. On the other hand, a compressive force in the circumferential direction is generated in the belt reinforcing layer 35 positioned radially outward from the bending neutral axis. However, the reinforcing cord 37 in the belt reinforcing layer 35 extends substantially parallel to the tire equator S. Therefore, the belt reinforcing layer 35 functions as a strong resistance against the compressive force as in the prior art.

However, in this example , of the belt plies 24 and 25, the belt ply that is closest to the belt reinforcing layer 35 is the proximity belt ply 25, and the belt ply that is next to the proximity belt ply 25 is the next proximity belt. When the ply 24 is used, the inclination angle A of the belt cords 27 and 26 embedded in the adjacent belt ply 25 and the next adjacent belt ply 24 with respect to the tire equator S is in the above order, that is, in the order of the belt cords 27 and 26. Thus, the above-described tensile force is applied to the next adjacent belt ply 24 in which the belt cord 26 having a relatively large inclination angle A with respect to the tire equator S is embedded.

  Here, since the belt cord 26 of the next adjacent belt ply 24 disposed at a position away from the belt reinforcing layer 36 is inclined at an inclination angle A that is relatively large with respect to the tire equator S, The coating rubber is extended by the tensile force, so that the next adjacent belt ply 24 disposed on one side (tensile side) of the neutral axis of bending has a reduced resistance function against the tensile force. As a result, the out-of-plane bending stiffness in the circumferential direction of the entire tread portion 15 (rigidity against bending with the crease in the tire width direction) decreases, thereby reducing the vertical spring constant of the pneumatic tire 11 and overcoming the protrusion. The feeling of pushing up and the feeling of ruggedness on rough roads are reduced, and the riding comfort performance is improved, and the ground contact length is increased to increase the ground contact area and improve the steering stability.

  The belt cord 26 in the next adjacent belt ply 24 is preferably inclined at an inclination angle A of 45 degrees or more with respect to the tire equator S. The reason for this is that if the inclination angle A is 45 degrees or more, the belt cord 26 extends rather in the width direction rather than in the circumferential direction. This is because the amount of extension of the coating rubber in the meantime increases, and thereby the out-of-plane bending rigidity in the circumferential direction of the tread portion 15 can be surely reduced. However, if the inclination angle A exceeds 85 degrees, the in-plane shear rigidity may decrease, and the value of the lateral force generated during cornering may not be sufficient. Therefore, the inclination angle A should be 85 degrees or less. Is preferred.

3 and 4 are diagrams showing another example of the pneumatic tire . In this example , the belt reinforcing layer 40 is disposed so as to overlap the belt layer 41 between the belt layer 41 and the carcass layer 18, and the belt layer 41 is arranged in addition to the adjacent belt ply 42 and the next adjacent belt ply 43. The belt reinforcement layer 40 is composed of three belt plies including a separation belt ply 44 that is the most separated from the belt reinforcement layer 40. As a result, the proximity belt ply 42, the next proximity belt ply 43, and the separation belt ply 44 are arranged in this order toward the outside in the radial direction, and are bent near the boundary between the proximity belt ply 42 and the next proximity belt ply 43. There will be a neutral axis.

As a result, when the tread portion 15 is deformed so as to be flat from the arc shape in the ground contact region, circumferential tension is applied to the belt reinforcing layer 40 and the proximity belt ply 42, while the next proximity belt ply 43 and the separation belt ply 44. A circumferential compressive force is generated. In this example , the inclination angle A of the belt cord 47 embedded in the separation belt ply 44 with respect to the tire equator S is defined as the inclination angle A of the belt cord 46 embedded in the next adjacent belt ply 43 with respect to the tire equator S. The inclination angle is larger than A. In this way, even when the belt layer 41 is composed of three belt plies, the coating rubber positioned between the belt cords 47 in the added separation belt ply 44 is easily compressed. Therefore, the out-of-plane bending stiffness in the circumferential direction in the tread portion 15 can be sufficiently reduced.

Further, in this example , the belt reinforcing layer 40 is disposed between the belt layer 41 and the carcass layer 18 as described above, but when the belt reinforcing layer 40 is provided at such a position, the belt The belt reinforcing layer 40 arranged on the inner side in the radial direction of the layer 41 can suppress the radial growth of the tread portion 15 toward the outer side in the radial direction during high speed running. Steering stability at the time of high-speed traveling equivalent to that arranged at can be ensured.

Next, Embodiment 1 of the present invention will be described. Oite to this embodiment, the inclination angle A with respect to the tire equator S of the belt cord 47 is embedded in the separation belt ply 44, the tire equator S of the belt cord 46 is embedded in the next adjacent belt ply 43 It is as the same as the inclination angle A with respect to. In this case, since the belt ply having the same cord inclination angle can be used as the next proximity belt ply 43 and the separation belt ply 44, the pneumatic tire 11 can be easily manufactured and the cost can be reduced. Other configurations and operations are the same as in the above example .

Next, Test Example 1 will be described. In this test, the inclination angle of the reinforcement cord in the belt reinforcement layer is 0 degree, and the inclination angle A of the belt cord in the proximity, next approach, and separation belt plies is 50 degrees to the right, 50 degrees to the left, and to the right. In the conventional tire 1 as shown in FIGS. 3 and 4 which is 50 degrees, the inclination angle A of the belt cord in the proximity, next approach, and separation belt plies is 50 degrees to the right, 70 degrees to the left, and 70 degrees to the right. , as in the tire 1 others are the same as the conventional tire 1, the proximity, the next adjacent, the inclination angle a is right up 70 degrees each belt cords in spaced belt plies, a left-side up 50 degrees, right up 30 degrees, other A comparative tire 1 similar to the conventional tire 1 was prepared.

  Here, each of the tires described above is a tire for a high-performance passenger car, the size is 245 / 55R17, and the carcass layer of each tire is embedded with a nylon cord that intersects the tire equator S at 90 degrees 2 It was composed of one carcass ply. In addition, belt cords made by twisting three steel filaments each having a diameter of 0.15 mm are embedded in the belt ply of each tire at an interval of 1.0 mm, while the belt reinforcement layer of each tire is aromatic. Reinforcement cords with a diameter of 0.7 mm twisted from polyamide filaments were driven and embedded at an interval of 1.0 mm.

Next, after filling each tire with an internal pressure of 220 kPa, a paint is applied to the outer surface of the tread portion, and the ground shape is transferred to the paper by pressing against a white paper while applying a load of 6 kN before the paint dries. did. Thereafter, the maximum length in the tire equator direction in the ground contact shape of each tire was measured. As a result, although there were a conventional In the tire 1 132 mm, in the exemplary tire 1, the circumferential direction of the plane bending rigidity was increased until either et al 1 45 mm that was reduced. In comparison tire 1 , the out-of-plane bending rigidity was increased, so that it decreased to 125 mm.

Next, after mounting each of the tires on a high-performance passenger car, the vehicle was run on a dry road circuit at a maximum speed of 200 km / h, and the steering stability was evaluated by a skilled test driver. When representing the evaluation in points full marks as 100 points, the conventional tire 1, 70 points, respectively in Comparative tire 1 has a 60-point, in the exemplary tire 1 it was improved steering stability and 75 points. This is presumably because the contact area is increased and the contact area is expanded as described above .

Next, the joints of the bumpy road and the highway prepared for the test course were passed by the same passenger car as described above, and the vibration ride comfort was evaluated by a skilled test driver. When the evaluation are expressed in 10 steps, conventional tire 1, were respectively the comparative tire 1 6,5, was improved also 8 and the vibration riding comfortability in the exemplary tire 1.

  The present invention can be applied to the industrial field of pneumatic tires in which a belt reinforcing layer that overlaps the belt layer is disposed in the tread portion.

It is meridian sectional drawing which shows an example of a pneumatic tire . It is a partially broken plan view of the tread portion. It is meridian sectional drawing which shows the other example of a pneumatic tire . It is a partially broken plan view of the tread portion.

11 ... Pneumatic tire 12 ... Bead core
18 ... Carcass layer 23 ... Belt layer
24 ... Next proximity belt ply 25 ... Proximity belt ply
26, 27 ... belt cord 31 ... tread
36 ... Belt reinforcement layer 44 ... Separation belt ply S ... Tire equator A ... Inclination angle

Claims (1)

A carcass layer whose both ends in the width direction are folded around a bead core and extend in a toroidal shape, and a non-extensible belt cord which is disposed radially outward of the carcass layer and is inclined in the opposite direction with respect to the tire equator S a belt layer composed of buried three base Rutopurai in a tread disposed radially outward of the belt layer is arranged so as to overlap with the belt layer, a non-extending substantially in parallel to the tire equator S therein In a pneumatic tire provided with a belt reinforcing layer in which an extensible reinforcing cord is embedded, of the belt plies, the belt ply closest to the belt reinforcing layer is adjacent to the adjacent belt ply and next to the adjacent belt ply. The belt cord tire equator is embedded in the adjacent belt ply and the next adjacent belt ply. With a large inclination angle A in the order for, when the farthest belt ply from belts reinforcing layer and spaced apart from the belt ply, the inclination angle with respect to the tire equator S of the belt cords embedded in the separation belt in the ply A pneumatic tire characterized in that A is the same as the inclination angle A of the belt cord embedded in the next adjacent belt ply with respect to the tire equator S.

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