JP6331606B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that can shorten the fastest lap time during circuit running.

  Conventionally, as disclosed in Patent Document 1, in order to prevent a lap time from dropping sharply during circuit running, a belt under-reinforcing layer in which a cord extends substantially in the tire circumferential direction between a carcass layer and a belt layer. It is known to provide

JP 2013-230744 A

  However, in the pneumatic tire described in Patent Document 1, although the lap time can be reduced rapidly, the cornering force cannot be sufficiently increased, and the fastest lap time may not be sufficiently shortened.

  Accordingly, an object of the present invention is to provide a pneumatic tire that can shorten the fastest lap time during circuit running.

  In the first aspect of the present invention, in a pneumatic tire including a carcass layer and a belt layer disposed on the outer side in the tire radial direction of the carcass layer, the belt layer is sequentially disposed from the inner side toward the outer side in the tire radial direction. The first belt, the second belt, and the third belt, and the total thickness of the first belt, the second belt, and the third belt is 2.3 mm to 3.6 mm, and constitutes the third belt A pneumatic tire is provided in which the cord is made of metal and forms an angle of 90 ° ± 10 ° with the tire circumferential direction.

  In the second aspect of the present invention, the thickness of the third belt is smaller than the thickness of the first belt and smaller than the thickness of the second belt.

  In the third aspect of the present invention, the cord constituting the third belt has a diameter of 0.15 mm to 0.69 mm.

  In the fourth aspect of the present invention, the cord constituting the carcass layer forms an angle of 60 ° or more and 88 ° or less with the tire circumferential direction.

  In the fifth aspect of the present invention, the cords constituting the first belt and the second belt form an angle of 10 ° to 50 ° with the tire circumferential direction.

  In the sixth aspect of the present invention, the cords constituting the first belt and the second belt are made of a non-metallic material.

  In the seventh aspect of the present invention, the nonmetallic material is an aramid fiber.

  In an eighth aspect of the present invention, a pneumatic tire used as a racing tire is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which made it possible to shorten the fastest lap time at the time of circuit driving | running | working by improving the structure of a belt layer is provided.

FIG. 1 shows a partial tire meridional section of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a stacked state of the carcass layer and the belt layer of the pneumatic tire according to the embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention (the following basic modes and additional modes 1 to 7) will be described in detail with reference to the accompanying drawings. Note that these embodiments do not limit the present invention. In addition, constituent elements of the above embodiment include those that can be easily replaced by those skilled in the art and those that are substantially the same. Furthermore, various forms included in the above embodiments can be implemented in any combination.

  First, terms used in the description of the embodiments are defined as follows. The tire radial direction means a direction orthogonal to the rotation axis of the pneumatic tire. The inner side in the tire radial direction means the side toward the rotation axis in the tire radial direction. The outer side in the tire radial direction means the side away from the rotation axis in the tire radial direction. The tire circumferential direction means a direction around the rotation axis as a central axis. The tire width direction means a direction parallel to the rotation axis. The inner side in the tire width direction means the side toward the tire equatorial plane CL in the tire width direction. The outer side in the tire width direction means a side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL means a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire.

[Basic form]
Hereinafter, the basic form of the pneumatic tire according to the present invention will be described. FIG. 1 shows a partial tire meridional section of a pneumatic tire according to an embodiment of the present invention.

  Although only a part is illustrated in FIG. 1, the pneumatic tire 1 includes a bead portion, a sidewall portion, a shoulder portion 3, and a tread portion 5 from the inner side in the tire radial direction toward the outer side in a tire meridional sectional view. The pneumatic tire 1 includes a carcass layer 7 that extends from the tread portion 5 to the bead portions on both sides and is wound around a pair of bead cores, and the outer side in the tire radial direction of the carcass layer 7 in the tire meridional section view. The belt layer 9 and the belt cover layer 11 are sequentially formed.

  A tread rubber 51 is disposed in the tread portion 5. Although not shown, a tread pattern having a predetermined pattern may be formed on the tread rubber in order to improve traveling performance on a wet road surface. Moreover, the inner liner 13 comprised from the rubber sheet is affixed on the tire inner peripheral surface. The inner liner 13 may be disposed only on a part of the tire inner peripheral surface in the tire meridian cross-sectional view, or may not be disposed on the tire inner peripheral surface.

  The carcass layer 7 is disposed between the pair of bead portions and forms a tire skeleton. The carcass layer 7 is composed of two layers of carcass and includes a first carcass 71 and a second carcass 73 that are sequentially arranged from the inner side to the outer side in the tire radial direction. The carcass layer 7 imparts rigidity to the pneumatic tire 1, thereby enhancing durability against the load and impact of the pneumatic tire 1. The carcass layer 7 may be a single layer or three layers.

  FIG. 2 is a schematic diagram showing a stacked state of the carcass layer and the belt layer of the pneumatic tire according to the embodiment of the present invention. As shown in FIG. 2, the first carcass 71 and the second carcass 73 are each composed of a plurality of cords 71a, 73a and rubber covering the cords. The cords 71a and 73a are made of a metallic material or a non-metallic material. The metal material is, for example, steel. Non-metallic materials are, for example, organic fibers such as aramid, polyester, nylon, rayon, or composites thereof.

  The belt layer 9 is disposed outside the carcass layer 7 in the tire radial direction. The belt layer 9 includes a first belt 91, a second belt 93, and a third belt 95 that are configured by three layers of belts and are sequentially disposed from the inner side to the outer side in the tire radial direction. The belt layer 9 increases the rigidity of the tread portion 5 by tightening the carcass layer 7 from the outer side in the tire radial direction toward the inner side.

  As shown in FIG. 2, each of the first belt 91, the second belt 93, and the third belt 95 includes a plurality of cords 91a, 93a, and 95a, and rubber that covers the cords. The cords 91a and 93a are made of a metallic material or a non-metallic material. The metal material is, for example, steel. Non-metallic materials are, for example, organic fibers such as aramid, polyester, nylon, rayon, or composites thereof. By disposing the first belt 91 and the second belt 93 on the tread portion 5, the rigidity of the tread portion 5, particularly the in-plane bending rigidity can be increased.

  In the present specification, the in-plane bending rigidity means rigidity against deformation of the tread portion 5 in the in-plane direction of the contact surface (any direction in the contact surface). The cornering force can be increased by increasing the in-plane bending rigidity. On the other hand, in this specification, the out-of-plane bending rigidity means rigidity against deformation of the tread portion 5 in the out-of-plane direction of the ground contact surface.

  If the out-of-plane bending rigidity is too high, the contact area of the tread portion 5 becomes small at low load, and the original cornering force generated mainly by the first belt 91 and the second belt 93 cannot be obtained. In addition, if the out-of-plane bending rigidity with respect to the compression force in the tire width direction is low, buckling is likely to occur in the vicinity of the center of the tread portion 5 in the tire width direction from the road surface. Also in this case, the contact area of the tread portion 5 is reduced, and the original cornering force cannot be obtained.

  The cord 95a constituting the third belt 95 forms an angle of 90 ° ± 10 ° with the tire circumferential direction. In the example shown in FIG. 2, the angle β3 formed by the cord 95a constituting the third belt 95 with the tire circumferential direction is 90 °. The cord 95a of the third belt 95 is made of a metal material. The metal material is, for example, steel. Steel has a much higher strength and elastic modulus than organic fibers. Moreover, unlike the cord of an organic fiber, the steel cord has rigidity and strength against compression as well as axial tension.

  By disposing the third belt 95 having the above-described configuration on the pneumatic tire 1, the rigidity of the tread portion 5, particularly the out-of-plane bending rigidity with respect to the force in the compression direction in the tire width direction can be increased. Can be suppressed. As a result, a decrease in cornering force can be suppressed, so that the fastest lap time during circuit running can be shortened.

  The total thickness of the first belt 91, the second belt 93, and the third belt 95 is not less than 2.3 mm and not more than 3.6 mm. By setting the total thickness to 2.3 mm or more, the in-plane bending rigidity and the out-of-plane bending rigidity of the tread portion 5 can be ensured. On the other hand, by setting the total thickness to 3.6 mm or less, it is possible to suppress deterioration of the lap time due to the belt layer 9 and thus the entire pneumatic tire 1 becoming heavy.

  As shown in FIG. 1, the belt cover layer 11 is disposed on the outer side in the tire radial direction of the third belt 95. The belt cover layer 11 increases the rigidity of the tread portion 5 by tightening the carcass layer 7 together with the belt layer 9 from the outer side in the tire radial direction toward the inner side. The belt cover layer 11 may be two or more layers.

  The pneumatic tire 1 is obtained through normal manufacturing processes, that is, a tire material mixing process, a tire material processing process, a green tire molding process, a vulcanization process, and an inspection process after vulcanization.

[Additional form]
Next, additional embodiments 1 to 7 that can be optionally implemented in the basic embodiment of the pneumatic tire according to the present invention will be described.

(Additional form 1)
It is preferable that the thickness of the third belt 95 is smaller than the thickness of the first belt 91 and smaller than the thickness of the second belt 93 (additional form 1).

  With this feature, the thickness of the entire belt layer 9 can be suppressed while ensuring the thickness of the first belt 91 and the second belt 93, and therefore the cornering generated mainly by the first belt 91 and the second belt 93. The belt layer 9 and thus the entire pneumatic tire 1 can be lightened without greatly reducing the force. As a result, the fastest lap time during circuit driving can be further shortened.

(Additional form 2)
In the basic form or the like (the basic form or the form in which the additional form 1 is combined with the basic form), the diameter of the cord 95a of the third belt 95 is not less than 0.15 mm and not more than 0.69 mm (additional form 2). preferable.

  By setting the diameter of the cord 95a of the third belt 95 to 0.15 mm or more, the out-of-plane bending rigidity against the force on the compression side in the tire width direction can be further increased, and the buckling can be further suppressed. As a result, a decrease in cornering force can be suppressed, so that the fastest lap time during circuit running can be further shortened. In addition, by setting the diameter of the cord 95a of the third belt 95 to 0.69 mm or less, the third belt 95 and thus the entire pneumatic tire 1 can be lightened. As a result, the fastest lap time during circuit driving can be further shortened.

  In addition, the said effect can be show | played by a higher level because the diameter of the code | cord | chord 95a of the 3rd belt 95 shall be 0.40 mm or more and 0.65 mm or less.

(Additional form 3)
In the basic form or the like (the basic form or a form in which at least one of the additional forms 1 and 2 is combined with the basic form), the cord constituting the carcass layer 7 forms an angle of 60 ° to 88 ° with the tire circumferential direction. (Additional form 3) is preferred.

  In the example shown in FIG. 2, the angle α1 formed by the cord 71a constituting the first carcass 71 and the tire circumferential direction is 80 °. Further, an angle α2 formed by the cord 73a constituting the second carcass 73 and the tire circumferential direction is also 80 °. The angle α1 and the angle α2 may be different values as long as they are within the above range.

  By making the angle of the cord constituting the carcass layer 7 with the tire circumferential direction 60 ° or more, it is possible to prevent the out-of-plane bending rigidity of the tread portion 5 from becoming too high, and to reduce the contact area of the tread portion 5 even at low loads. Can be secured. As a result, a decrease in cornering force can be suppressed, so that the fastest lap time during circuit running can be further shortened. Further, by setting the angle of the cord constituting the carcass layer 7 to the tire circumferential direction to be 88 ° or less, the out-of-plane bending rigidity of the tread portion 5 can be ensured, and the buckling can be further suppressed. . As a result, a decrease in cornering force can be suppressed, so that the fastest lap time during circuit running can be further shortened.

  In addition, the said effect can be show | played by a higher level by the angle which the code | cord | chord which comprises the carcass layer 7 makes | forms with the tire circumferential direction shall be 70 to 80 degree.

(Additional form 4)
In the basic form or the like (the basic form or the form in which at least one of the additional forms 1 to 3 is combined with the basic form), the cords 91a and 93a constituting the first belt 91 and the second belt 93 are in the tire circumferential direction. And an angle of 10 ° to 50 ° (additional form 4).

  In the example shown in FIG. 2, the angle β1 formed by the cord 91a constituting the first belt 91 and the tire circumferential direction is 30 °. The angle β2 formed by the cord 93a constituting the second belt 93 and the tire circumferential direction is also 30 °. The extending direction of the cord 91a and the extending direction of the cord 93a may be the same. Also, the angle β1 and the angle β2 may be different values as long as they are within the above range.

  By making the angle formed with the tire circumferential direction of the cords 91a and 93a constituting the first belt 91 and the second belt 93 10 ° or more, it is possible to prevent the out-of-plane bending rigidity of the tread portion 5 from becoming too high, and to reduce the load. Sometimes the ground contact area of the tread portion 5 can be secured. As a result, a decrease in cornering force can be suppressed, so that the fastest lap time during circuit running can be further shortened. Moreover, the in-plane bending rigidity of the tread part 5 can be ensured by setting the angle formed with the tire circumferential direction of the cords 91a and 93a constituting the first belt 91 and the second belt 93 to 50 ° or less. As a result, the cornering force can be further increased, so that the fastest lap time during circuit driving can be further shortened.

  In addition, the said effect can be show | played by a higher level by making the angle which makes the tire circumferential direction of the cords 91a and 93a which comprise the 1st belt 91 and the 2nd belt 93 into 15 degrees or more and 40 degrees or less.

(Additional form 5)
In the basic form or the like (the basic form or the form in which at least one of the additional forms 1 to 4 is combined with the basic form), the cords 91a and 93a constituting the first belt 91 and the second belt 93 are non-metallic materials. Preferably (additional form 5). As described above, the non-metallic material is an organic fiber such as aramid, polyester, nylon, rayon, or a composite thereof.

  Due to this feature, the first belt 91 and the second belt 93 and thus the entire pneumatic tire 1 are lightened, and the out-of-plane bending rigidity of the tread portion 5 is prevented from becoming too high. Can be secured. As a result, the fastest lap time during circuit driving can be further shortened.

(Additional form 6)
In the basic form or the like (form in which the additional form 5 is combined with the basic form), the nonmetallic material is preferably an aramid fiber (additional form 6).

  Since the tensile strength of the aramid fiber is particularly high among non-metallic materials, the material of the cords 91a and 93a constituting the first belt 91 and the second belt 93 is made of aramid fiber to further increase the in-plane bending rigidity. Can do. As a result, the cornering force can be further increased, so that the fastest lap time during circuit driving can be further shortened.

(Additional form 7)
In the basic form or the like (the basic form or the form in which at least one of the additional forms 1 to 6 is combined with the basic form), it is preferable that the pneumatic tire is used as a racing tire (additional form 7). .

  In this case, the pneumatic tire preferably includes two or more carcass layers, three belt layers, and one or more belt cover layers. Thereby, the in-plane rigidity and the out-of-plane rigidity of the tread portion can be further increased. As a result, the cornering force can be further increased, so that the fastest lap time during circuit driving can be further shortened. Moreover, it is preferable that the JIS A hardness of the tread rubber in the tread portion is 50 or less under the condition where the measurement temperature is 100 °. By this, the adhesiveness of the tread surface with respect to the road surface at the time of driving | running | working and the grip power of a tread surface by extension can be improved. As a result, the fastest lap time during circuit driving can be further shortened.

  Each condition shown in Table 1 (the number of carcass layers, the thickness of the belt layer, the thickness of the first belt, the thickness of the second belt, the thickness of the third belt, the angle formed by the cord forming the carcass layer with the tire circumferential direction (carcass Layer extension angle), an angle formed by the cord constituting the first belt with the tire circumferential direction (extension angle of the first belt), and an angle formed by the cord constituting the second belt with the tire circumferential direction (of the second belt). Extension angle), the angle formed by the cord constituting the third belt with the tire circumferential direction (extension angle of the third belt), the diameter of the cord of the third belt, the material of the first belt, the material of the second belt, 3 belt material, number of first belt cords driven per 50 mm cross-sectional width (number of first belt cords driven), number of second belt cord driven per 50 mm cross-sectional width (second belt cord driven) Book ), Changing the number of cords driven on the third belt per 50 mm in cross-section width (number of cords driven on the third belt) and the JIS A hardness of the tread rubber at a measurement temperature of 100 ° (JIS A hardness of the tread rubber)) A total of 12 pneumatic tires (test tires) of Conventional Example 1 and Examples 1 to 11 were produced.

  Each test tire had a tire size of 330 / 710R18, and four test tires were assembled on a 13J rim at a pressure of 120 kPa and mounted on a GT vehicle with a displacement of 3500 CC. For all these test tires, the fastest lap time was evaluated as follows. These results are also shown in Table 1.

(Fastest lap time)
The test driver drove 5 laps on the circuit for competition of about 3.7 km per lap, and the lap time was measured every lap. The shortest lap time among the five laps was recorded as the fastest lap time.

  According to the test results in Table 1, all of the pneumatic tires of Examples 1 to 11 belonging to the technical scope of the present invention are those of Conventional Example 1 that do not belong to the technical scope of the present invention. On the other hand, it can be seen that the fastest lap time is shortened.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 3 Shoulder part 5 Tread part 7 Carcass layer 71 1st carcass 71a Cord which comprises 1st carcass 71 73 2nd carcass 73a Cord which comprises 2nd carcass 9 9 Belt layer 91 1st belt 91a 1st belt 91 constituting the belt 93 second belt 93a constituting the second belt 93 95 third belt 95a constituting the third belt 95 11 belt cover layer 13 inner liner CL tire equatorial plane α1 constituting the first carcass 71 Angle formed by the cord 71a with the tire circumferential direction α2 Angle formed by the cord 73a constituting the second carcass 73 with the tire circumferential direction β1 Angle formed by the cord 91a constituting the first belt 91 with the tire circumferential direction β2 Constructing the second belt 93 Angle formed by the cord 93a to be made with the tire circumferential direction β3 The angle formed by the cord 95a constituting the three belt 95 and the tire circumferential direction

Claims (6)

In a pneumatic tire comprising a carcass layer and a belt layer disposed outside the carcass layer in the tire radial direction,
The belt layer includes a first belt, a second belt, and a third belt that are sequentially disposed from the inner side to the outer side in the tire radial direction;
The total thickness of the first belt, the second belt, and the third belt is 2.3 mm to 3.6 mm, the thickness of the third belt is smaller than the thickness of the first belt, and the second belt Smaller than the thickness,
A pneumatic tire for racing, wherein the cord constituting the third belt is made of metal and forms an angle of 90 ° ± 10 ° with the tire circumferential direction. The pneumatic tire for racing according to claim 1, wherein the cord has a diameter of 0.15 mm to 0.69 mm. The pneumatic tire for a race according to claim 1 or 2 , wherein the cord constituting the carcass layer forms an angle of 60 ° to 88 ° with the tire circumferential direction. The pneumatic tire for a race according to any one of claims 1 to 3 , wherein cords constituting the first belt and the second belt form an angle of 10 ° to 50 ° with a tire circumferential direction. The pneumatic tire for a race according to any one of claims 1 to 4 , wherein the cords constituting the first belt and the second belt are made of a nonmetallic material. The racing pneumatic tire according to claim 5 , wherein the non-metallic material is an aramid fiber.

Images