JP4601476B2 - Pneumatic radial tire for motorcycles - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a pneumatic radial tire for a motorcycle (hereinafter, also simply referred to as “tire”) that is used for a high-performance motorcycle generally called a supersport type that is grounded to the vicinity of a tread end and is driven at a high speed cornering. Specifically, the present invention relates to a low-flat pneumatic radial tire for a high-performance motorcycle that can improve the steering stability performance during high-speed cornering while maintaining various performances such as high-speed durability and straight-line stability.

  Most general motorcycles have a camber running (running the vehicle on its side) that is grounded in a range from 50% of the entire width of the tread surface to less than 75% at the cornering on a general road. It is normal.

  Therefore, in conventional conventional pneumatic tires for motorcycles, a belt layer that greatly affects the steering stability at the time of so-called high-speed cornering traveling, in which the vehicle body is greatly inclined and grounded to the vicinity of the tread end of the tire is traveled. There has been no pursuit of deep optimization of various bending stiffnesses and their mutual balance.

For example, Patent Document 1 improves the radial tires for motorcycles that can reduce the curvature and rigidity steps of the tire tread and improve ride comfort and driving stability, and Patent Document 2 improves the productivity of cords that constitute the reinforcing layer. At the same time, the tire reinforcement cord mainly for motorcycles that improves the steering stability of the tire is patented. In Patent Document 3, the radial tire for motorcycles that has improved wear resistance without impairing the running performance and handling performance is patented. In Reference 4, a tire having a belt layer formed by spirally winding a belt-like ply does not sacrifice excellent straight running stability, and the protrusion of the tread surface during high-speed rotation is extremely small and the durability is excellent. Further, in Patent Document 5, the durability and high-speed durability of a belt are improved at a low cost, and the road surface impact force absorption property of the tire is improved. The aim is to provide tires for motorcycles that improve uniformity characteristics and thereby exhibit excellent running stability, but in order to improve steering stability during high-speed cornering, It was not pursuing optimization for various bending rigidity of the belt layer.
JP-A-2-88308 JP-A-3-213402 JP-A-4-362402 JP-A-7-96712 Japanese Patent Laid-Open No. 2002-234032

  However, in recent years, with the advent of high-performance motorcycles called supersports types, it has become possible to enjoy sports driving on touring on a highway. In recent years, the number of so-called specific management areas for sports driving, which are not public roads such as practice fields and sports driving circuits, where riders can challenge the limits of maneuvering skills and enjoy drastic sports driving has increased. Now you can enjoy sports driving. Under such circumstances, the so-called large camber running, in which the vehicle body is tilted sideways deeply, increases the dissatisfaction that the steering stability performance at the time of high-speed cornering is not sufficient in the conventional belt rigidity balance design. I came.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic radial tire for a motorcycle that maintains various performances such as high-speed durability and straight-running stability and has improved steering stability performance during high-speed cornering.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the above object can be achieved by adopting the following configuration, and has completed the present invention.
That is, a pneumatic radial tire for a motorcycle according to the present invention includes a tread portion, a pair of sidewall portions disposed radially inward from both edges of the tread portion, and a tire radial direction of the sidewall portion. A carcass layer composed of at least one carcass ply in which each portion is reinforced between bead cores embedded in the bead portion and the textile cord is covered with rubber; In a pneumatic radial tire for a motorcycle, comprising at least one steel spiral belt spirally formed on the outer side in the tire radial direction substantially parallel to the tire equatorial plane.
The steel cord forming the steel spiral belt is an open twisted cord having a 1 × 2 structure, and has an overlapping portion between the cords adjacent in the belt width direction.

  In the pneumatic radial tire for motorcycles of the present invention, the overlapping portion preferably has 2 to 4 stages in order to obtain the desired effect. The steel cord preferably has a filament diameter of 0.12 to 0.40 mm and a filament strength of 104 to 128N. Furthermore, the number of steel cords driven into the belt is preferably 40 to 55/25 mm. Furthermore, the filament constituting the steel cord is preferably an open twisted cord having a brazing width of 0.4 to 0.8 mm and a brazing pitch of 8 to 12 mm.

  In a pneumatic radial tire for a high-performance motorcycle, since the bending rigidity balance of the belt layer has a great influence on the vehicle, in the present invention, out of the bending rigidity of the tread portion, out-of-plane bending rigidity (Sb) The belt surface stiffness equilibrium value expressed by the bending stiffness ratio (Sa / Sb) between the circumferential in-plane bending stiffness (Sa) and the circumferential in-plane bending stiffness (Sa) and the lateral out-of-plane bending stiffness (Sb). (K) is preferably within the following ranges for the following reasons.

  That is, when cornering high-performance motorcycles, especially the front wheel tires are braked when entering the corner, camber traveling and handling during cornering, raising the car body, exiting the corner, and again moving to high-speed straight traveling, And input / output is repeated violently. Among these, first, in braking, particularly in braking running in which some banking and handling are mixed in the vicinity of the corner entrance, the circumferential in-plane bending rigidity (Sa) of the tread portion is 5.1 N / mm ( 520 g / mm) or more.

  Next, when driving in corners that mix intense banking and handling, the tire crown should be flexibly and flexibly aligned in the out-of-plane bending direction of the tread, especially for motorcycle tires with a large tread curvature. It needs to be deformed to improve road holding performance. For that purpose, it is necessary to keep the widthwise out-of-plane bending rigidity (Sb) of the tread part to 7.7 N / mm (790 g / mm) or less, but if it is less than 4.9 N / mm (500 g / mm), the width The absolute value of directional out-of-plane bending stiffness is insufficient. Further, if the in-plane bending rigidity (Sa) in the circumferential direction of the belt is larger than 7.8 N / mm (800 g / mm), the tire crown portion can be appropriately and flexibly deformed based on the above range of the out-of-plane bending rigidity (Sb). Therefore, the in-plane bending rigidity (Sa) in the circumferential direction is preferably 7.8 N / mm (800 g / mm) or less.

  Furthermore, at the time of the intense cornering traveling, that is, from the posture close to the upright position in the high speed traveling state, the high speed cornering is entered, the deeper bank traveling is entered as it is, the high speed cornering is resumed to return to the upright posture, and the left and right cornering are mutually performed. When the switching is repeated, the circumferential in-plane bending stiffness and the lateral out-of-plane bending stiffness of the tread portion are intense, and the mutual switching of the main contributions is repeated, so the circumferential in-plane bending stiffness (Sa) and the transverse surface The belt surface rigidity equilibrium value (K) represented by the bending rigidity ratio (Sa / Sb) to the outer bending rigidity (Sb) is preferably in the range of 0.95 to 1.05. In other words, in the region outside the range of the K value, the surface rigidity balance balance blur (variation range) of the tread portion becomes too large, giving the rider a feeling of steering instability and degrading high-speed cornering performance. become.

  The tire of the present invention is mounted on a measurement rim defined by ETRTO, and the flatness ratio (SH) between the tire cross-section height SH in a no-load state during post-cure inflation in the tire vulcanization process and the maximum tread surface width TW. / TW) is particularly suitable as a pneumatic radial tire for a high-performance low-flat motorcycle having 0.50 to 0.85.

  Further, the present invention is a motorcycle characterized in that the pneumatic radial tire for a motorcycle according to the present invention is selected from the front and rear wheels having different types of the steel spiral belt, and is combined and mounted on the motorcycle. This is a method of attaching tires to the tire.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic radial tire for motorcycles which improved various steering stability performances at the time of high-speed cornering, maintaining various performances, such as high-speed durability and straight running stability, can be provided.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a pneumatic radial tire for a motorcycle according to an embodiment of the present invention.

  In FIG. 1, a pneumatic radial tire 1 for a motorcycle includes a tread portion 2, a pair of sidewall portions 3 disposed on the inner side in the tire radial direction from both edges of the tread portion 2, and tires of the sidewall portions 3. It consists of a bead portion 4 that continues inward in the radial direction. These parts are reinforced between the bead cores 7 embedded in the bead part 4 by the carcass layer 5. Further, at least one steel spiral belt 6 formed by spiral winding substantially parallel to the tire equatorial plane is disposed outside the carcass layer 5 in the tire radial direction.

  A tire as a preferred example of the present invention is a low flat tire that can be suitably applied to a high-performance motorcycle called a super sports type in recent years. Specifically, the tire is mounted on a measurement rim defined by ETRTO, The flatness ratio (SH / TW) between the tire cross-section height SH in a no-load state during post-cure inflation in the tire vulcanization process and the tread surface maximum width TW is 0.50 to 0.85.

  The carcass layer 5 is composed of at least one carcass ply in which a cord forming 60 to 90 degrees with respect to the tire equatorial plane is covered with rubber (one layer in the illustrated example). As the carcass ply cord, an organic fiber cord such as a rayon cord, a nylon cord, or a polyester cord can be suitably used.

  The steel spiral belt 6 is made of a steel cord and its covering rubber, and is disposed substantially parallel to the equator plane of the tire 1. Substantially means that the inclination angle of the steel cord with respect to the equatorial plane is less than 1 °.

  In the present invention, in order to obtain desired width direction out-of-plane bending rigidity (Sb), circumferential in-plane bending rigidity (Sa), and belt surface rigidity equilibrium value (K), the steel cord forming the steel spiral belt 6 is provided. 2 and 3, twisted braided filaments are twisted to form an open twisted cord 8 having a 1 × 2 structure excellent in rubber penetration into the cord, and adjacent in the belt width direction. It is important to have an overlapping portion between the cords 8, preferably in 2 to 4 steps. At this time, the open twisted cords 8 are arranged substantially evenly in the belt width direction. Further, it is desirable that the filament strength, the number of cords to be driven, the brazing width and the pitch of the open twisted cord 8 are also within predetermined ranges.

  That is, the method of applying the force in the circumferential bending rigidity (Sa) of the belt is such that a force is applied to the center of the beam with both ends of the filament on the shaft. Therefore, the higher the strength of the filament, the greater the number of cords driven, and the smaller the brazing of the filament, the greater the circumferential in-plane bending stiffness (Sa). Therefore, the filament diameter is less than 0.12 mm and the filament strength is less than 104 N, the cord driving number is less than 40/25 mm, or the brazing width and pitch of the filament is more than 0.8 mm and less than 8 mm, respectively. In this case, the circumferential in-plane bending rigidity (Sa) is less than 5.1 N / mm (520 g / mm), which is not preferable. Conversely, if the filament diameter is greater than 0.40 mm and the filament strength is greater than 128 N, the number of cords driven is greater than 55/25 mm, or the brazing width and pitch of the filament is less than 0.4 mm and greater than 12 mm, respectively. In this case, the circumferential in-plane bending rigidity (Sa) is excessively increased, and the belt surface rigidity equilibrium value (K) exceeds 1.05, which is also not preferable. Regarding the belt in-plane bending rigidity (Sa), the cord structure is less affected by other parameters, and when the number of filaments per cord increases, the contribution rate of brazing of the filament also decreases.

  On the other hand, the method of applying the force of the belt width direction out-of-plane bending rigidity (Sb) is not a method of applying a force to the center of the beam with both ends of the filament on the shaft. If the total number of filaments is the same, the number of filaments per cord is reduced, the number of cords to be driven is increased, the brazing of the filaments is increased to reduce the gap between cords and cords, and the belt's widthwise out-of-plane bending stiffness ( Sb) can be increased. Furthermore, the effect increases when the filaments between adjacent cords overlap each other. From such a viewpoint, the filament diameter is 0.12 to 0.40 mm, the filament strength is 104 to 128 N, the number of cords to be corded into the belt layer is 40 to 55/25 mm, and the brazing width and pitch of the filament are each 0.00. In the case of 4 to 0.8 mm and 8 to 12 mm, the belt-direction out-of-plane bending stiffness (Sb) is 4.9 to 7.7 N / mm (500 to 790 g / mm), and the belt surface stiffness equilibrium value (K) can be controlled within the range of 0.95 to 1.05.

Hereinafter, the present invention will be described based on examples.
Front wheel tires (size: 120 / 70ZR17, rim width: 3.50 inches, internal pressure: 206 kPa) and rear wheel tires (size: 190 / 55ZR17, rim width: 6.5) satisfying the conditions shown in Table 1 and Table 2 below, respectively. (00 inch, internal pressure: 186 kPa) was mounted on a 500 cc racer type motorcycle in the combination shown in Table 3 below, and the steering stability feeling at the time of high-speed cornering was evaluated. In the evaluation, the value of Conventional Example 3 is set to 100 and displayed in the index, and the larger the numerical value, the better the result.

In Tables 1 and 2, the circumferential in-plane bending stiffness (Sa) and the lateral out-of-plane bending stiffness (Sb) were measured as follows.
First, with the road surface portion of the test tire having no pattern groove and the same tread rubber disposed at the same thickness as the measurement sample, the tire equator direction and the tire equator direction 90 degrees as shown in FIG. It cut out with the belt in width 15mm (A and B in FIG. 4). Next, as shown in FIG. 5, the circumferential in-plane bending stiffness (Sa) is set by rotating 90 ° of the cut out (A) in the equator direction and placing it on the measuring device (in the tire axial direction equivalent direction). The width direction out-of-plane bending stiffness (Sb) is set by placing (B) cut out in the direction of 90 degrees with respect to the tire equator and setting it down (in the direction corresponding to the tire radial direction). / Displacement) was measured. The obtained results are shown in Tables 1 and 2 below.

1 is a cross-sectional view of a pneumatic radial tire for a motorcycle according to an embodiment of the present invention. It is a perspective view which shows the state by which the open twisted cord of 1x2 structure which forms the steel spiral belt which concerns on this invention has an overlap part and is arrange | positioned between this cord adjacent to the belt width direction. It is an expanded sectional view of the steel spiral belt which concerns on this invention. It is explanatory drawing which shows the cutout part of the sample for a measurement from the tread part of a test tire. It is explanatory drawing which shows the measuring method of the bending rigidity of the cut-out sample.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic radial tire for motorcycles 2 Tread part 3 Side wall part 4 Bead part 5 Carcass layer 6 Steel spiral belt 7 Bead core 8 Open twist cord

Claims (9)

A tread portion, a pair of sidewall portions disposed on the inner side in the tire radial direction from both edges of the tread portion, and a bead portion continuous on the inner side in the tire radial direction of the sidewall portion. A carcass layer comprising at least one carcass ply reinforced between bead cores embedded in each other and coated with a textile cord with rubber, and substantially outside of the carcass layer in the tire radial direction with respect to the tire equatorial plane. In a pneumatic radial tire for a motorcycle comprising at least one layer of a steel spiral belt formed by spiral winding in parallel,
A pneumatic radial tire for a motorcycle, wherein the steel cord forming the steel spiral belt is an open twisted cord having a 1 × 2 structure, and has an overlapping portion between the cords adjacent in the belt width direction.   The pneumatic radial tire for a motorcycle according to claim 1, wherein the overlapping portion has 2 to 4 stages.   The pneumatic radial tire for a motorcycle according to claim 1 or 2, wherein the steel cord has a filament diameter of 0.12 to 0.40 mm and a filament strength of 104 to 128N.   The pneumatic radial tire for a motorcycle according to any one of claims 1 to 3, wherein the number of steel cords driven into the belt is 40 to 55 pieces / 25 mm.   The pneumatic braided motorcycle according to any one of claims 1 to 4, wherein a brazing width of the filament constituting the steel cord is 0.4 to 0.8 mm and a brazing pitch is 8 to 12 mm. Radial tire.   Of the bending rigidity of the tread portion, the lateral out-of-plane bending rigidity (Sb) is 4.9 to 7.7 N / mm (500 to 790 g / mm), and the circumferential in-plane bending rigidity (Sa) is 5. The pneumatic radial tire for a motorcycle according to any one of claims 1 to 5, which is 1 to 7.8 N / mm (520 to 800 g / mm).   A belt surface stiffness equilibrium value (K) expressed by a bending stiffness ratio (Sa / Sb) between the circumferential in-plane bending stiffness (Sa) and the widthwise out-of-plane bending stiffness (Sb) is 0.95 to 1. The pneumatic radial tire for a motorcycle according to claim 6, which is within a range of 05.   Mounted on a measurement rim specified by ETRTO, the flatness ratio (SH / TW) between the tire cross-section height SH in the unloaded state during post-cure inflation in the tire vulcanization process and the maximum tread surface width TW is 0. The pneumatic radial tire for a motorcycle according to any one of claims 1 to 7, which is 50 to 0.85.   The pneumatic radial tire for a motorcycle according to any one of claims 1 to 8, wherein different types of the steel spiral belt are selected for the front and rear wheels, and the motorcycle is combined and mounted on the motorcycle. How to install tires on motorcycles.

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