JP2012051482A - Motorcycle tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration in running while improving rotating performance and wear resistant performance.SOLUTION: A motorcycle tire 1 includes: a carcass 6 leading to a bead core of a bead part through a sidewall part 3 from a tread part 2; and a band layer 9 arranged in the outside of a radial direction of the carcass 6 and the inside of the tread part 2. The band layer 9 includes a band ply 10 spirally wound at an angle of five degrees or lower to the circumferential direction of the tire with a band cord 11. The band ply 10 includes: a center ply 10C arranged in a tread center part Cr including a tire equator C; a pair of edge plies 10E arranged in the outermost side of the axial direction of the tire; and a pair of shoulder plies 10S arranged between the center ply 10C and the edge ply 10E. The band cord 11 of the center ply 10C and the edge ply 10E includes an organic fiber cord. In addition, the band cord 11 of the shoulder ply 10S includes a steel cord.

Description

  The present invention relates to a motorcycle tire that can suppress force variation (vibration) during traveling while improving turning performance and wear resistance performance.

  In recent years, there has been a strong demand for motorcycle tires with excellent turning performance as the performance of vehicles increases. In order to meet these requirements, motorcycle tires are proposed that have a band ply in which a band cord made of steel cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction on the outside of the carcass. (For example, refer to Patent Document 1 below). In such a motorcycle tire, the band ply can be restrained by tightening the tread portion thereof to improve turning performance and high-speed stability.

JP 2005-001629 A

  By the way, as shown in FIG. 5, when assembling the rim of the motorcycle tire a, the bead portion c is moved inward in the tire axial direction by moving the tire bar b leaning against the rim flange rf of the rim r like a lever. It is pushed in and incorporated into the inside of the rim flange rf of the rim r. At this time, the tread end portion dt of the tread portion d is greatly deformed.

  Due to the deformation of the tread end portion dt, the band ply f inside thereof is also greatly deformed, and plastic deformation tends to occur in a part of the steel cord of the band ply f. In the tire a in which such deformation has occurred, there has been a problem that even if the internal pressure is filled, the deformation of the band ply f does not completely return to its original state, and thus force variation (vibration) is likely to occur during traveling.

  In addition, the motorcycle tire a in which the band ply f is composed only of a steel cord has a greater out-of-plane bending rigidity of the tread portion d than that using an organic fiber cord, so that the tread portion d can be flexed when grounded. There is a tendency that it cannot be deformed. For this reason, motorcycle tires in which the band cords are all made of steel cords also have a problem in that the ground pressure cannot be sufficiently dispersed and the wear resistance performance tends to deteriorate.

  The present invention has been devised in view of the actual situation as described above, and among the band plies of the band layer disposed on the outside in the radial direction of the carcass and inside the tread portion, Based on the fact that the band cord of the edge ply is an organic fiber cord and the band cord of the shoulder ply between them is a steel cord, while improving the turning performance and wear resistance performance, force variation (vibration) The main objective is to provide a tire for a motorcycle that can suppress the above).

  The invention according to claim 1 of the present invention includes a carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, and a band layer disposed outside the carcass in the radial direction and inside the tread portion. A tire for a motorcycle, wherein the band layer includes a band ply in which a band cord is spirally wound at an angle of 5 degrees or less with respect to a tire circumferential direction, and the band ply is a tire equator. Including a center ply disposed in the center portion of the tread, a pair of edge plies disposed on the outermost side in the tire axial direction, and a pair of shoulder plies disposed between the center ply and the edge ply, The band cords of the center ply and the edge ply are made of organic fiber cords, and the band cords of the shoulder ply are Characterized by comprising the steel cord.

  The invention according to claim 2 is the motorcycle tire according to claim 1, wherein the width of the edge ply in the tire axial direction is 5 to 15% of the width of the band ply in the tire axial direction.

  The width of the center ply in the tire axial direction is 40 to 50% of the width of the band ply in the tire axial direction, and the width of the shoulder ply in the tire axial direction is The motorcycle tire according to claim 1 or 2, wherein the tire width is 15 to 25% of the width of the band ply in the tire axial direction.

  The invention according to claim 4 is the motorcycle tire according to any one of claims 1 to 3, wherein the organic fiber cord is an aramid fiber cord.

  According to a fifth aspect of the present invention, the carcass includes a main body portion extending from the tread portion through the sidewall portion to the bead core of the bead portion, and the bead core extending from the inner side in the tire axial direction toward the outer side. At least one carcass ply having a folded portion that is folded back, and the folded portion is wound up between the main body portion and the band ply, and an outer end of the folded portion is a tire shaft of the shoulder ply. The motorcycle tire according to any one of claims 1 to 4, wherein the tire is terminated at an inner side in a tire axial direction from an outer end in a direction.

  The invention according to claim 6 is the automatic according to claim 5, wherein the length along the band ply between the outer end of the folded portion and the outer end of the shoulder ply is 3 to 5 mm. This is a tire for motorcycles.

  In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values specified in a normal state with no load loaded with a normal rim and filled with a normal internal pressure.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA. For ETRTO, use "Measuring Rim".

  The “regular internal pressure” is the air pressure defined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” indicates “highest air pressure”, and TRA indicates “TIRE” The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “INFLATION PRESSURE” in the case of ETRTO.

  The motorcycle tire of the present invention includes a band layer formed of a band ply in which a band cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction. The band ply includes a center ply disposed in the center of the tread including the tire equator, a pair of edge plies disposed on the outermost side in the tire axial direction, and a pair of shoulder plies disposed between the center ply and the edge ply. In addition, the band cord of the center ply and the edge ply is made of an organic fiber cord, and the band cord of the shoulder ply is made of a steel cord.

  In such motorcycle tires, the edge ply band cords are made of organic fiber cords that are less plastically deformed and have a lower bending rigidity than steel cords. As a result, the rim assembly performance is improved, and the plastic deformation of the band cord after the rim assembly is prevented, so that the occurrence of force variation (vibration) during traveling can be suppressed.

  Further, since the band cord of the center ply is also made of an organic fiber cord, the tread portion can be flexibly deformed by reducing the out-of-plane bending rigidity of the center portion of the tread. Accordingly, the wear resistance can be improved by dispersing the ground pressure during straight running.

  Furthermore, since the band cord of the shoulder ply is made of a steel cord having a large rigidity, the turning performance can be improved. Further, since the steel cord is disposed only on the shoulder ply, the tire mass is not excessively increased.

1 is a cross-sectional view showing a motorcycle tire of the present embodiment. It is sectional drawing which expands and shows an edge ply and a shoulder ply. It is a perspective view which expands and shows a belt-like ply. (A) is sectional drawing parallel to the tire equator surface which shows the state which the tire for motorcycles of this embodiment grounded to the road surface, (b) is a top view which shows the grounding surface of (a). 1 is a cross-sectional view showing a motorcycle tire when assembling a rim.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a motorcycle tire (hereinafter, simply referred to as “tire”) 1 of the present embodiment has an outer surface of a tread 2 between tread ends 2 e and 2 e on the outer side in the tire radial direction. The curve is convex and smoothly curved, and TW, which is the distance in the tire axial direction between the tread ends 2e and 2e, is the maximum tire width.

  Further, the tire 1 includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2. A band layer 9 disposed on the outer side in the tire radial direction of the belt layer 7 is provided.

  The carcass 6 includes a main body portion 6a extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 embedded in the bead portion 4, and the bead core 5 connected to the main body portion 6a from the inner side toward the outer side in the tire axial direction. And at least one carcass ply 6A, 6B having the folded portion 6b folded back in this embodiment. The “inner and outer” is distinguished by the position of the tire equator C. Further, a bead apex 8 made of, for example, hard rubber is disposed between the main body portion 6a and the folded portion 6b of the carcass plies 6A and 6B.

  In the present embodiment, of the inner and outer carcass plies 6A and 6B, the folded portion 6b of the outer carcass ply 6B is between the main body 6a and the band layer 9, more specifically, the main body 6a and the belt. A high-turn nap structure is wound up between the layers 7 and terminates. Such an external carcass ply 6B increases the rigidity of the sidewall portion 3 and helps to achieve both a high level of riding comfort and steering stability. In the present embodiment, only the outer carcass ply 6B has a high turn nap structure, but the inner carcass ply 6A may also have a high turn nap structure in order to increase the rigidity of the sidewall portion 3.

  The carcass plies 6A and 6B are arranged such that each carcass cord is inclined with respect to the tire equator C at an angle of, for example, 60 to 90 degrees, and a radial or semi-radial structure is preferable. Moreover, as a carcass cord, organic fiber cords, such as nylon, polyester, or rayon, are employ | adopted, for example.

  The belt layer 7 is composed of one or more belt plies 7A, in the present embodiment, in which belt cords are arranged at an angle of, for example, 5 to 30 degrees with respect to the tire circumferential direction. As the belt cord, for example, various organic fiber cords such as nylon, rayon, polyester, and aramid, and steel cords are appropriately employed.

  As shown in FIGS. 1 and 2, the band layer 9 includes a single band ply 10 disposed on the outer side in the tire radial direction of the belt layer 7. The band ply 10 is formed as a so-called full band ply arranged over substantially the entire width of the tread portion 2. The “substantially full width of the tread portion 2” means that the width PW of the band ply 10 in the tire axial direction is 85 to 100% of the width TW of the tread portion 2 in the tire axial direction. Such a band ply 10 restrains the tread portion 2 by tightening and suppressing the growth of the outer diameter of the belt layer 7 during high-speed running and the buckling deformation of the belt layer 7 during turning. And help to improve high speed stability.

  Further, as shown in FIGS. 2 and 3, the band ply 10 is rubber-coated with a topping rubber 12 by, for example, arranging two to four (three in this embodiment) band cords 11 in parallel. The belt-like ply 13 is formed by spirally winding at an angle of 5 degrees or less with respect to the tire circumferential direction. Since such a band ply 10 has a so-called jointless structure with no joints, the band ply 10 is excellent in tire uniformity and serves to firmly and reliably restrain the belt layer 7. The belt-like ply 13 of the present embodiment is wound so that the side edges 13t, 13t of the belt-like ply 13 are in contact with each other, but may be wound while the side edges 13t, 13t are overlapped with each other. The side edges 13t and 13t may be wound apart from each other.

  As shown in FIG. 1, the band ply 10 of the present embodiment includes a center ply 10 </ b> C disposed in the tread center portion Cr including the tire equator C, and a pair of edge plies 10 </ b> E disposed on the outermost side in the tire axial direction. 10E and a pair of shoulder plies 10S, 10S arranged between the center ply 10C and the edge ply 10E.

  The center ply 10C of the present embodiment is disposed in the tread center portion Cr of the tread portion 2 that is mainly grounded when traveling straight. The center in the tire axial direction of the center ply 10C coincides with the tire equator C. The band cord 11 of the center ply 10C is made of an organic fiber cord that is less susceptible to plastic deformation than the steel cord and has a low bending rigidity.

  Further, the edge ply 10E is disposed on the outermost side in the tire axial direction, and an organic fiber cord is adopted for the band cord 11 of the edge ply 10E as well as the center ply 11C.

  Further, the width SW in the tire axial direction of the shoulder ply 10S is arranged in the shoulder region Sh of the tread portion 2 that is mainly grounded during turning. In addition, a steel cord having a higher bending rigidity than the organic fiber cord is adopted as the band cord of the shoulder ply 10S.

  As described above, in the present invention, the band cord 11 of the edge ply 10E is made of an organic fiber cord that is less plastically deformed and has a lower bending rigidity than the steel cord. For example, even when the rim is assembled, the band cord 11 is flexibly deformed together with the tread portion 2. Improve rim assembly. Further, even after the rim is assembled, the deformation of the tread portion 2 is easily restored, so that occurrence of force variation (vibration) during traveling can be suppressed.

  Further, since the band cord 11 of the center ply 10C is made of an organic fiber cord, the out-of-plane bending rigidity of the tread center portion Cr is relaxed, and the tread center portion Cr can be flexibly deformed. As a result, as shown in FIG. 4, the tread portion 2 increases the area of the ground contact surface 15 when traveling straight, and the ground contact pressure decreases. Therefore, the distortion ST of the tread rubber 2G during contact is suppressed and wear resistance is reduced. Performance and rolling resistance performance are further improved. In addition, the tread center portion Cr can absorb the impact from the road surface and the like due to its flexibility, so that the riding comfort can be improved.

  Further, as shown in FIG. 1, the band cord 11 of the shoulder ply 10S is made of a steel cord having a larger bending rigidity than that of the center ply 10C, so that the out-of-plane bending rigidity of the shoulder region Sh of the tread portion 2 is increased. The turning performance can be improved. Moreover, since only the band cord 11 of the shoulder ply 10S is made of a steel cord, the band cord 11 can suppress an excessive increase in tire mass.

  If the width EW in the tire axial direction of the edge ply 10E is too small, the deformation of the tread end when the rim is assembled extends to the shoulder ply 10S, and the band cord 11 of the shoulder ply 10S made of steel cord is plastic. Deformation may occur, and conversely, if it is too large, the rigidity of the shoulder region Sh of the tread portion 2 may be reduced, and the turning performance may be reduced. From this point of view, the width EW of the edge ply 10E in the tire axial direction is preferably 5% or more, preferably 15% or less, more preferably 10% of the width PW of the band ply 10 in the tire axial direction. % Or less is desirable.

  Further, if the width CW of the center ply 10C in the tire axial direction is too small, the ground contact pressure during straight traveling cannot be sufficiently reduced, and the wear resistance performance may not be improved. Even if it is too much, the rigidity of the shoulder region Sh of the tread portion 2 may be reduced, and the turning performance may not be improved. From this point of view, the width CW of the center ply 10C in the tire axial direction is preferably 40% or more, preferably 50% or less, more preferably 45% of the width PW of the band ply 10 in the tire axial direction. % Or less is desirable.

  Furthermore, if the width SW in the tire axial direction of the shoulder ply 10S is too small, the out-of-plane bending rigidity of the shoulder region Sh of the tread portion 2 cannot be sufficiently increased, and the turning performance may not be improved. Even if it is too large, the rigidity of the shoulder region Sh is excessively increased, the transient characteristics are deteriorated, and the band cord 11 of the shoulder ply 10S may be plastically deformed when the rim is assembled. From such a viewpoint, the width SW of the shoulder ply 10S in the tire axial direction is preferably 15% or more, more preferably 17% or more, and preferably 25% of the width PW of the band ply 10 in the tire axial direction. % Or less, more preferably 23% or less.

  As the band cord 11 of the center ply 10C and the edge ply 10E, for example, an aramid fiber cord, nylon, polyester, or the like can be appropriately selected. However, high speed stability and turning performance are suppressed while suppressing force variation (vibration) during running. Aramid fiber cords that can be improved are preferred. In this embodiment, the band cord 11 made of an aramid fiber cord is used for the center ply 10C and the edge ply 10E. However, for example, a nylon cord may be used for the band cord 11 of the edge ply 10E. Since such an edge ply 10E deforms more flexibly together with the tread portion 2, it is possible to improve the rim assembly property.

  As shown in FIGS. 1 and 2, the outer end 6bt of the folded portion 6b of the outer carcass ply 6B is preferably terminated on the inner side in the tire axial direction than the outer end 10St in the tire axial direction of the shoulder ply 10S. Thereby, since the folding | turning part 6b of the outer carcass ply 6B is distribute | arranged over the whole inner region of the edge ply 10E, the rigidity of the tread edge part side of the tread part 2 can be improved. Therefore, the tread portion 2 can reduce the rigidity difference between the edge ply 10E side and the shoulder ply 10S side, and can further improve the turning performance and the transient characteristics.

  In addition, since the carcass cord of the present embodiment is also composed of an organic fiber cord, it can be deformed flexibly when assembling the rim, thereby preventing plastic deformation. This facilitates rim assembly and suppresses the occurrence of force variation (vibration) during traveling.

  If the length L1 along the band ply 10 between the outer end 6bt of the folded portion 6b and the outer end 10St of the shoulder ply 10S is too small, the outer end 10St of the shoulder ply 10S and the inner end 10Ei of the edge ply 10E There is a risk that a rigidity step may occur between the two, and defects such as deformations and scratches due to the rigidity step may occur, or transient characteristics may deteriorate. On the contrary, if it is too large, the shoulder region Sh side of the tread portion 2 may be deteriorated. The rigidity becomes excessively large, and the transient characteristics may be deteriorated. From such a viewpoint, the length L1 along the band ply 10 between the outer end 6bt of the folded portion 6b and the outer end 10St of the shoulder ply 10S is preferably 3 mm or more, and preferably 5 mm or less.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

Motorcycle tires having the basic structure shown in FIG. 1 and having the band ply and the carcass ply shown in Table 1 were prototyped and their performance was tested. The common specifications are as follows.
Tire size: 180 / 55ZR17
Rim size: MT5.5 × 17
Tread tire width TW: 185mm
Carcass ply Carcass cord material: Nylon Carcass cord construction: 1400dtex / 2
Ends: 35 / 5cm
Belt ply Belt cord cord material: Nylon Belt cord construction: 1400dtex / 2
Ends: 35 / 5cm
Band ply Band ply width in tire axial direction PW: 177mm
Band cord (steel)
Code structure: 3 × 3 × 0.17HT
Band cord (aramid)
Code structure: 1670dtex / 2
Ends: 50 / 5cm
Band cord (nylon)
Code structure: 1400dtex / 2
Ends: 50 / 5cm
The test method is as follows.

<Force variation (vibration)>
Each sample tire was assembled into a rim by hand using a tire lever on the rim, filled with an internal pressure of 250 kPa, and a variation value (mm) of RRO (radial runout) was measured. The smaller the numerical value, the smaller the force variation (vibration) during running.

<Abrasion resistance>
Each test tire was assembled on the rim, filled with an internal pressure of 250 MPa, mounted on a motorcycle with a displacement of 750 cc, and traveled about 1000 km on a dry asphalt road surface. Thereafter, the average amount of wear in the central region of the tread portion (average value of the amount of wear (mm) at six locations on the tire circumference) was measured. The smaller the value, the smaller the wear amount and the better.

<High-speed stability, transient characteristics, turning performance>
Each test tire is mounted on the motorcycle under the above conditions, and the `` high-speed stability '', `` transient characteristics '' and `` turning performance '' when driving around the dry asphalt road test course are evaluated by sensory evaluation by the driver. Evaluation was made by a 5-point method. The larger the value, the better.

<Rim assembly performance>
Each sample tire was mounted on a regular rim by hand assembly using a tire lever, and evaluated by an index with Comparative Example 2 set to 100 by an operator's sensory evaluation. The larger the value, the better the rim assembly performance.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the motorcycle tire according to the example can suppress the force variation (vibration) during traveling while improving the turning performance and the wear resistance performance.

DESCRIPTION OF SYMBOLS 1 Motorcycle tire 2 Tread part 3 Side wall part 6 Carcass 9 Band layer 10 Band ply 10C Center ply 10E Edge ply 10S Shoulder ply 11 Band cord Cr Tread center part

Claims (6)

A motorcycle tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a band layer disposed outside the carcass in the radial direction and inside the tread portion,
The band layer comprises a band ply in which a band cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction,
The band ply includes a center ply disposed in a tread center including the tire equator, a pair of edge plies disposed on the outermost side in the tire axial direction, and a pair disposed between the center ply and the edge ply. Including shoulder ply
The band cords of the center ply and the edge ply are made of organic fiber cords,
A tire for a motorcycle, wherein the band cord of the shoulder ply is made of a steel cord.   The motorcycle tire according to claim 1, wherein a width of the edge ply in the tire axial direction is 5 to 15% of a width of the band ply in the tire axial direction. The width in the tire axial direction of the center ply is 40 to 50% of the width in the tire axial direction of the band ply,
The motorcycle tire according to claim 1 or 2, wherein a width of the shoulder ply in the tire axial direction is 15 to 25% of a width of the band ply in the tire axial direction.   The motorcycle tire according to any one of claims 1 to 3, wherein the organic fiber cord is an aramid fiber cord. The carcass has at least one main body portion that extends from the tread portion through the sidewall portion to the bead core of the bead portion, and a turn-back portion that is connected to the main body portion and is turned around from the inner side to the outer side in the tire axial direction. With a piece of carcass ply,
The folded portion is wound up between the main body portion and the band ply,
The motorcycle tire according to any one of claims 1 to 4, wherein an outer end of the folded portion terminates at an inner side in the tire axial direction than an outer end of the shoulder ply in the tire axial direction.   The motorcycle tire according to claim 5, wherein a length along the band ply between an outer end of the folded portion and an outer end of the shoulder ply is 3 to 5 mm.

Images