JP2007022374A - Pneumatic radial tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the straight-ahead traveling and turning stability at high speed of a tire, without deterioration of tire weight and side stiffness. <P>SOLUTION: In the pneumatic radial tire for a motorcycle is provided with one layer of a main belt 9 made by spirally winding a non-expansion cord around an outer periphery side of a crown 7 of a radial carcass 5 over the width of crown 7, and is not more than 80% in a flat ratio. A center auxiliary belt layer 11 made from organic fiber cords is arranged at a center part of the crown 7 on an inner peripheral side of the main belt 9. Side part auxiliary belts layers 13 made from high elastic cords are arranged on both side parts of the crown 7. The high elastic cords of the side part auxiliary belt layers 13 are extended in direction intersecting each other. An arrangement clearance along a tread portion tread surface 14 of both side part auxiliary belt layers 13 is made to be 20 to 50% of the width TW of the tread surface 14. An inside edge of each side auxiliary belt layer 13 and a side edge of the center auxiliary belt layer 11 are overlapped each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire for a motorcycle including a main belt having a spiral winding structure of one or a plurality of non-extensible cords with rubber coating, and in particular, high-speed straight running stability. And a technology for improving high-speed turning stability at the same time without deteriorating maneuverability due to an increase in tire weight.

  Conventionally, with the increase in popularity of so-called touring and sports motorcycles, the performance of the motorcycle itself has been improved, and the tires can also run harder. Therefore, dimensional correspondence has been made by flattening.

  In addition, in recent years, as the performance of motorcycles has been further improved and the demand for improved high-speed durability has further increased, instead of the conventional bias belt, the highly elastic cord has excellent tire radial expansion restraining force against high-speed rotation. The so-called mono-directional spiral belt (hereinafter referred to as “MSB belt”) in which the highly elastic cord extends in the circumferential direction of the tread portion has been introduced. As high elastic cords, aramid fiber cords, steel cords and the like have been used.

  By the way, this MSB belt made of a highly elastic cord extending in the circumferential direction of the tread portion is effective in suppressing the radial expansion of the tread portion at the time of high-speed rotation of the tire due to its structure, but is related to the radial carcass. Under the tire crown, in other words, the lateral rigidity of the tread is low, and the central region of the tread tends to be recessed in the tire lumen against acceleration / deceleration and road surface irregularities during straight running. Therefore, there has been a problem that advanced riding techniques are inevitable in order to maintain steering stability against road surface disturbances during high-speed turning and straight traveling.

  Therefore, in order to deal with such a problem, each of Patent Documents 1 and 2 includes a large spiral cord layer on the outer peripheral side of the MSB belt that covers the crown area of the radial carcass over almost the entire width thereof. Further, there are disclosed technologies for disposing one or more belt auxiliary layers over the entire width of the MSB belt or covering only the side areas of the MSB belt. However, the stability during straight running was still low.

  That is, under the tread reinforcement structure including the radial carcass and the MSB belt, as described above, the central region of the tread portion is likely to be buckled, and the seat is subjected to load rolling of the tire. Bending deformation occurs continuously and repeatedly in the circumferential direction of the tread portion and inhibits straight running stability. In this case, a belt auxiliary layer is disposed on the outer peripheral side of the MSB belt to the full width. Even in the reinforcement structure described in Patent Document 1, the belt auxiliary layer is positioned on the compression side from the neutral axis of the bending against the buckling deformation as described above, so that a sufficient buckling resistance can be obtained. This is more significant in the reinforcing structure described in Patent Document 2, in which the belt auxiliary layer is provided only in the side region of the MSB belt and the belt auxiliary layer is not provided in the central region of the belt. Met.

For this reason, it is possible to improve the straight running stability by increasing the number of carcass plies constituting the radial carcass to increase the case rigidity, and as described in Patent Document 3, the reinforcing layer is provided on the side portion of the tire. It has been proposed to increase the stability by suppressing the wobbling during straight traveling by adding side to increase the side rigidity.
JP 2004-67058 A JP 2001-206209 A JP-A-5-246210

  However, according to the prior art that increases the number of laminated carcass plies in order to increase the case rigidity, the tire weight will also increase, so there is a problem that the maneuverability during handling, cornering, etc. deteriorates. Further, according to the reinforcing structure described in Patent Document 3 that increases the side rigidity, the flexibility of the sidewall portion during turning is reduced, so that the grounding property of the tread surface, that is, the road holding property is improved. There was a problem that turning performance deteriorated.

  The present invention has been made in order to solve such problems of the prior art, and the object of the present invention is to avoid an excessive increase in tire weight and to improve the tire side rigidity. It is an object of the present invention to provide a pneumatic radial tire for a motorcycle that can simultaneously improve high-speed straight-line stability and high-speed turning stability without any increase.

  A pneumatic radial tire for a motorcycle according to the present invention includes a pair of sidewall portions, a tread portion connected to a toroidal portion on both sidewall portions, and a bead portion provided on an inner peripheral side of each sidewall portion. Formed by one or more carcass plies made of a plurality of organic fiber cords of relatively high elasticity, for example, rubber-coated, extending parallel to each other at an angle in a range of 75 ° to 90 ° with respect to the equator plane. In addition, a radial carcass is provided to reinforce each of the above-mentioned parts by winding the both side portions around the bead core embedded in the bead portion, for example, from the inner side to the outer side in the tire width direction. For example, a non-extensible cord coated with rubber is provided on the outer peripheral side of the crown region of the carcass in a posture extending in the circumferential direction of the crown region. A main belt formed of one layer of a spiral cord layer spirally wound in the width direction in units of several, for example, a full width of the crown region, that is, along a peripheral in the cross section in the radial direction of the radial carcass The flatness is 80% or less provided at the full width, and on the inner peripheral side of the main belt, at the central portion of the crown region, 40 ° to 90 ° with respect to the tire equatorial plane, more preferably For example, on the outer peripheral side of the main belt, a central part auxiliary belt layer made of a plurality of organic fiber cords extending at an angle in the range of 60 ° to 90 °, for example, made of a rubber coating, is disposed. Extending at an angle in the range of 40 ° to 90 °, preferably 45 ° to 60 °, preferably 45 ° to 60 ° with respect to the tire equator, From high elastic cord A plurality of side partial auxiliary belt layers, and the high elastic cords of the side partial auxiliary belt layers are mutually crossed, for example, mutually in relation to the tire equatorial plane. In addition to extending in the opposite direction, the distance between the side portion auxiliary belt layers along the tread surface is set to a range of 20% to 50% of the surface width of the tread surface, and each side portion auxiliary The inner edge of the belt layer and the side edge of the central auxiliary belt layer are arranged so as not to overlap each other, for example, with an interval exceeding 5 times the diameter of the non-extensible cord of the main belt. is there.

  In such a tire, the central partial auxiliary belt layer disposed on the inner peripheral side of the main belt can be disposed adjacent to the inner peripheral side of the radial carcass.

  Preferably, the non-extensible cord of the main belt is a steel cord or an organic fiber cord such as an aramid fiber cord having a cord strength of 130 N or more, and preferably, the organic fiber cord of the central auxiliary belt layer is The cord strength is 80 N or more, for example, a fiber cord such as nylon or rayon.

  And preferably, the highly elastic cord of the side portion auxiliary belt layer is a steel cord or an organic fiber cord having a cord strength of 80 N or more, more preferably 100 N or more, for example, an aramid fiber cord.

  In the pneumatic radial tire according to the present invention, in the central portion of the crown region of the radial carcass, on the inner peripheral side of the main belt, a range of 40 ° to 90 °, preferably 60 ° to 90 ° with respect to the tire equatorial plane. By disposing the central partial auxiliary belt layer made of the organic fiber cord extending at the inner angle, it is possible to increase the lateral rigidity of the disposition area and sufficiently ensure stability during straight traveling.

  By the way, when such a central partial auxiliary belt layer is arranged on the inner peripheral side of the radial carcass, the central partial auxiliary belt layer is centered on the radial carcass with respect to buckling deformation in the central area of the tread portion. Since it can be located on the tension side of the neutral axis of the deformation, it can effectively counter the buckling deformation and further improve the high-speed straight running stability.

  If the extension angle of the organic fiber cord of the central portion auxiliary belt layer with respect to the tire equatorial plane is less than 40 °, the lateral rigidity of the region where the reinforcing belt layer is disposed cannot be increased as expected, It becomes difficult to ensure excellent high-speed straight-line stability.

  Moreover, in this tire, it extends at an angle in a range of 40 ° to 90 °, preferably 45 ° to 60 ° with respect to the tire equatorial plane, for example, on the outer peripheral side of the main belt at both side portions of the crown region. While arranging each side part auxiliary belt layer which consists of high elastic cords, the separation interval which divides the center part of the crown area of those side part auxiliary belt layers is 20%-of the creeping width of the tread part tread. For a caliber angle of up to ± 15 ° given to a range of 50%, that is, when a motorcycle equipped with tires is turned, the side partial auxiliary belt layer is within the region corresponding to the ground contact surface. The tread part is designed especially for high-speed cornering by making the spacing apart so as not to enter, and by extending the high elastic cords of the respective side part auxiliary belt layers so as to cross each other. It can exhibit a high cornering stability on the basis of an increase of the transverse stiffness of the side region.

  Here, when the side portion auxiliary belt layer is disposed on the inner peripheral side of the main belt, the shear rigidity is reduced as compared with the case where it is disposed on the outer peripheral side of the main belt, and the cord angle When the angle is less than 40 °, an increase in the tensile strength of the belt in the side region of the tread portion is small, so that it is difficult to improve stability during high-speed turning.

  By the way, the distance between each side partial auxiliary belt layer is set in the range of 20% to 50% of the creepage width of the tread surface. In the so-called large camber traveling, in which the vehicle body is turned with a large inclination, the side part auxiliary belt layers are obtained under the knowledge that a camber angle of ± 15 ° to 50 ° is given to the vehicle body. This is to ensure excellent stability at the time of more advanced high-speed turning by letting it enter the region corresponding to the tread contact surface in such a large camber traveling and exhibit the required function. .

  In the tire configured as described above, a large rigidity is provided between the high-speed straight-running stability required region in the central portion of the crown region and the high-speed turning stability required region in the side portion of the crown region, that is, at the boundary between these two regions. If a step occurs, stress concentration on the side edges of each auxiliary belt layer overlaps when driving at high speed, leading to a decrease in the durability of the case, so here the central part auxiliary belt layer and the side part Adopting a reinforcing structure in which the adjacent side edges of the auxiliary belt layer are arranged so as not to overlap each other, preferably at a distance exceeding 5 times the diameter of the non-extensible cord of the main belt. Yes.

  In such a tire, when the non-extensible cord of the main belt is a steel cord or an organic fiber cord having a cord strength of 130 N or more, especially an aramid fiber cord, an excessive weight increase of the tire can be prevented. This is because when the organic fiber cord of the central portion auxiliary belt layer is a cord having a cord strength of 80 N or more, and the high elastic cord of the side portion auxiliary belt layer is a steel cord or a cord strength of 80 N or more. The same applies to each of the organic fiber cords.

  FIG. 1 is a cross-sectional view in the tire width direction showing an embodiment of the present invention, and FIG. 2 is a development of a main part showing a reinforcing structure of the tire shown in FIG.

The pneumatic radial tire for motorcycles shown here has a flatness ratio of 80% or less, a pair of sidewall portions 1, a tread portion 2 connected to the side wall portions 1 in a toroidal manner, and each sidewall. The bead part 3 provided in the inner peripheral side of the part 1 is provided.
Here, a plurality of rubber-coated organic fiber cords 4, for example, one or more nylon fiber cords, extending parallel to each other at an angle in the range of 75 ° to 90 ° with respect to the tire equatorial plane E, Then, a radial carcass 5 that is formed by a single carcass ply 1 and reinforces each of the above-described parts 1, 2, and 3 is provided to extend toroidal, and both side parts of this radial carcass 5 are provided on each bead part 3. The ring-shaped bead core 6 is embedded and locked from the inner side to the outer side in the tire width direction, and the outer peripheral side of the crown region 7 of the radial carcass 5 is covered with rubber. A spa in which an extensible cord 8, for example, an aramid fiber cord, is spirally wound in the width direction with one or a plurality of cords in the circumferential orientation of the crown region 7 as a unit. A main belt 9 that covers the crown region 7 over its entire width is constituted by one layer of the Ilar cord layer.

  Further, here, in the central portion of the crown region 7, a range of 40 ° to 90 ° with respect to the tire equatorial plane E between the inner periphery of the main belt 9, more precisely between the main belt 9 and the radial carcass 5. A plurality of rubber-coated organic fiber cords 10, for example, nylon fiber cords, and a central portion of the auxiliary belt layer 11, preferably extending at an angle in the range of 60 ° to 90 °. Extending at an angle in the range of 40 ° to 90 °, preferably 45 ° to 60 ° with respect to the tire equator plane E, adjacent to the outer peripheral side of the main belt 9 at both side portions of the region 7. A plurality of rubber-coated high-elasticity cords 12, for example, one side portion auxiliary belt layer 13 made of steel cord, is disposed.

  By the way, in each side part auxiliary | assistant belt layer 13 here, the direction where each highly elastic cord 12 cross | intersects each other, and the place shown in FIG. Further, the distance between the respective auxiliary belt layers 13 along the tread portion tread surface 14 is, for example, the creepage width TW of the tread surface 14 around the tire equatorial plane E. The range is 20% to 50%.

  Furthermore, as shown in the drawing, the inner edge of each side partial auxiliary belt layer 13 and the side edge of the central partial auxiliary belt layer 11 do not overlap each other and are spaced in the direction along the tread surface 14. Arrange without leaving.

  FIG. 3 is a cross-sectional view in the width direction showing another embodiment, in particular, in that the central partial auxiliary belt layer 11 is disposed adjacent to the inner peripheral side of the radial carcass 5. The tire is different in configuration.

  Example in which the size of the rear tire of a motorcycle is 190 / 50ZR17M / C and the size of the front tire is 120 / 70ZR17M / C, both of the tire structures according to the present invention are used. For each of the conventional examples with the conventional structure, the high speed straight running stability and the high speed turning stability were evaluated with the feeling of the test driver, and the results shown in Table 1 were obtained.

  According to the results shown in Table 1, both Examples 1 and 2 are the same as the conventional example in terms of both high-speed straight running stability and high-speed turning stability, mainly due to the presence of the central partial auxiliary belt layer. It is clear that superior results can be obtained. In particular, in Example 2, the center partial auxiliary belt layer is disposed on the inner peripheral side of the radial carcass, so that particularly excellent high-speed straight running stability is achieved. I understand that I can demonstrate it.

It is sectional drawing of the tire width direction which shows embodiment of this invention. It is a principal part expanded view which shows the reinforcement structure of the tire shown in FIG. It is sectional drawing similar to FIG. 1 which shows other embodiment of this invention. It is sectional drawing similar to FIG. 1 which shows a conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Side wall part 2 Tread part 3 Bead part 4,10 Organic fiber cord 5 Radial carcass 6 Bead core 7 Crown area 8 Non-extensible cord 9 Main belt 11 Central part auxiliary | assistant belt layer 12 High elastic cord 13 Side part auxiliary belt layer 14 Tread surface E Tire equatorial surface TW Creepage width

Claims (5)

A pair of sidewall portions, a tread portion connected to the toroidal portion on both sidewall portions, and a bead portion provided on the inner peripheral side of each sidewall portion, with an angle in the range of 75 ° to 90 ° with respect to the tire equatorial plane. Formed by one or more carcass plies made of extending organic fiber cords, and provided with a radial carcass that winds and locks both side portions around a bead core embedded in the bead portion to reinforce each of the above portions In addition, on the outer peripheral side of the crown region of the radial carcass, a non-extensible cord is formed by a single layer of a spiral cord layer that is spirally wound in the width direction with the crown region extending in the circumferential direction. A pneumatic radial tire for a motorcycle having a flatness ratio of 80% or less, comprising a belt,
On the inner peripheral side of the main belt, a central portion auxiliary belt layer made of an organic fiber cord extending at an angle in the range of 40 ° to 90 ° with respect to the tire equatorial plane is disposed in the central portion of the crown region. In addition, each side portion auxiliary belt layer made of a highly elastic cord extending at an angle in the range of 40 ° to 90 ° with respect to the tire equatorial plane is disposed on both side portions of the crown region. ,
The high elastic cords of each of the side partial auxiliary belt layers are extended in a direction crossing each other, and the arrangement interval of the side partial auxiliary belt layers along the tread surface is determined by the creepage width of the tread surface. Pneumatic radial tire for motorcycles in which the inner edge of each side partial auxiliary belt layer and the side edge of the central partial auxiliary belt layer are arranged without overlapping each other in a range of 20% to 50%. .   The pneumatic radial tire for a motorcycle according to claim 1, wherein the central auxiliary belt layer is disposed adjacent to the inner peripheral side of the radial carcass.   The pneumatic radial tire for a motorcycle according to claim 1 or 2, wherein the non-extensible cord of the main belt is a steel cord or an organic fiber cord having a cord strength of 130 N or more.   The pneumatic radial tire for a motorcycle according to any one of claims 1 to 3, wherein the organic fiber cord of the central auxiliary belt layer is a cord having a cord strength of 80 N or more. The pneumatic radial tire for a motorcycle according to any one of claims 1 to 4, wherein the highly elastic cord of the side portion auxiliary belt layer is a steel cord or an organic fiber cord having a cord strength of 80 N or more.

Images