JP4456380B2 - Motorcycle tires - Google Patents

Description

  The present invention relates to a motorcycle tire that is suitable as a front wheel of a large motorcycle and has improved riding comfort while ensuring excellent steering stability.

  In recent years, with the development of highway networks, even motorcycles are becoming larger and faster. In a tire used for such a high-speed and large-sized motorcycle, as shown in FIG. 5, a band cord is spirally wound outside the carcass a composed of two carcass plies in a radial arrangement substantially parallel to the tire circumferential direction. The structure provided with the band layer b is often used.

  In this structure, the carcass a consists of two plies, so the side rigidity is sufficiently ensured and the rigidity balance between the tread rigidity and the side rigidity is also excellent, so that the tires are swung during turning at high speeds. There is an advantage that satisfactory steering stability can be exhibited, such as lack of. On the other hand, however, the ride comfort is inferior to that of carcass a consisting of a single ply.

  Patent Documents 1 and 2 include motorcycle tires that achieve both ride comfort and steering stability.

JP-A-6-24207 JP 2003-39916 A

  Therefore, the present invention can secure a sufficient balance between the side rigidity and the tread rigidity, while ensuring the driving stability as good as or better than that of a two-ply carcass tire. An object of the present invention is to provide a motorcycle tire that is improved to the same level as a carcass single-ply tire.

The invention of claim 1 of the present invention is a carcass in which a body portion extending from a tread portion through a sidewall portion to a bead core of a bead portion is provided with a series of folded portions that are folded back from the inner side in the tire axial direction around the bead core. A motorcycle tire having a band layer made of a band ply disposed inside the tread and outside the carcass and spirally wound with a band cord at an angle of 5 degrees or less with respect to the tire circumferential direction. There,
The carcass is composed of one carcass ply in which carcass cords are arranged at an angle of 65 to 87 ° with respect to the tire circumferential direction, and the folded portion has an overlapping portion that overlaps the band layer on the inside in the radial direction. And have a break
Between the band ply and the carcass main body, a belt layer made of a belt ply in which a belt cord is arranged at an angle of 45 to 87 ° with respect to the tire circumferential direction is provided.
Moreover, the band width W1 along the band layer of the band layer is 80 to 98% of the tread width TW along the tread surface of the tread surface, and the belt width W2 along the belt layer of the belt layer is the tread width TW. 80-98% of
The folded portion of the carcass is interrupted on the outer side in the tire axial direction without crossing the tire equatorial plane, and the overlapping width Wa along the carcass of the overlapping portion is 15 to 35% of the band width W1. Yes.

According to a second aspect of the present invention, the belt layer is formed of a single belt ply, and the inclination direction of the belt cord is different from the inclination direction of the carcass cord in the main body.

According to a third aspect of the present invention, the belt layer includes two belt plies, and the belt cords are inclined in different directions between the two belt plies.

  According to a fourth aspect of the present invention, the belt layer is disposed between a main body portion and a folded portion of the carcass.

  Since the present invention is configured as described above, the side rigidity and the tread rigidity can be ensured in a well-balanced and sufficient manner, and the ride comfort can be greatly improved while ensuring excellent steering stability.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a meridional sectional view of a motorcycle tire according to the present invention, and FIG. 2 is a diagram schematically showing the arrangement of carcass cords, band cords and belt cords arranged on the tire in a plane.

  In FIG. 1, a motorcycle tire 1 (hereinafter referred to as a tire 1) has a tread portion 2 in which a tread surface 2S curves in a convex arc shape from the tire equator C to the tread end Te, and the tread end Te, Since the tire axial distance between Te forms the maximum tire width, turning at a large bank angle is enabled. 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 band layer disposed on the inner side of the tread portion 2 and on the radially outer side of the carcass 6. 7 is arranged.

  The band layer 7 is composed of one or more band plies 7A in which the band cord is spirally wound at an angle β of 5 degrees or less with respect to the tire circumferential direction. As the band cord, nylon, rayon, aromatic polyamide, etc. Organic fiber cords and steel cords can be used. In this example, the band layer 7 is composed of one band ply 7A of steel cord.

  The band layer 7 has a band width W1 in the tire axial direction along the band layer 7 in a range of 80 to 98% of a tread width TW in the tire axial direction along the tread surface 2S of the tread surface 2S. This reinforces substantially the entire width of the tread portion 2 with a hoop effect, and suppresses changes in the tire cross-sectional shape during traveling, thereby exhibiting excellent high-speed durability and high-speed traveling performance.

  The carcass 6 is composed of a single carcass ply 6A in which the carcass cord is arranged at an angle α of 65 to 87 ° with respect to the tire circumferential direction. The carcass cord is an organic fiber cord such as nylon, rayon, or aromatic polyamide. Is used. The carcass ply 6A includes a series of folded portions 6b that are folded from the inner side to the outer side in the tire axial direction around the bead core 5 at both ends of the main body portion 6a spanned between the bead cores 5 and 5. Between the bead core 6b and the folded portion 6b, an apex rubber rubber 8 for bead reinforcement extending in a radially outward direction from the bead core 5 is disposed. The radial height h1 of the apex rubber rubber 8 from the bead base line BL is smaller than the radial height he of the tread end Te. Preferably, the lower limit is 35% or more of the height he. Is 40% or more, and the upper limit is 70% or less, further 60% or less.

  The carcass 6 has a high turn-up structure in which the folded portion 6b passes through the sidewall portion 3 and is then sandwiched between the main body portion 6a and the band layer 7 and terminates in the tread portion 2. Thus, the folded portion 6b forms an overlapping portion 20 that overlaps with the band layer 7 on the inner side in the radial direction. In this example, the folded portion 6b is interrupted on the outer side in the tire axial direction without crossing the tire equatorial plane Co. That is, the folded portions 6b, 6b are spaced apart from each other without overlapping each other. The thing of a form is illustrated.

  Thus, in the present invention, the carcass 6 has a high turn-up structure having the overlapping portion 20, and the cord angle α is 65 to 87 °, and the carcass cord is between the main body portion 6a and the folded portion 6b. By adopting a triangle structure that crosses at an angle of at least 6 °, it is possible to obtain the same high side rigidity as two carcass plies while having one carcass ply 6A. Can be achieved at a high level.

If the cord angle α is greater than 87 °, the side rigidity is insufficient, and satisfactory steering stability cannot be secured. Conversely, if the cord angle α is less than 65 °, it is disadvantageous for high-speed durability and ride comfort. Therefore, the upper limit value of the cord angle α is preferably 85 ° or less, more preferably 80 ° or less, and the lower limit value is preferably 67 ° or more.

  In order to effectively exhibit the above-described side rigidity improvement effect, the overlapping portion 20 is provided, and the front end side of the folded portion 6b is sandwiched between the band layer 7 and the main body portion 6a and firmly fixed. Is important, and this also increases the tread stiffness. Therefore, the overlapping width Wa along the carcass 6 of the overlapping portion 20 is preferably 15% or more of the band width W1. However, as in the first embodiment, when the folded portions 6b, 6b have a hollow shape that does not overlap, if the overlap width Wa is too wide, the rigidity balance in the tread surface tends to be impaired. The transitional characteristics are reduced, such as lack of smoothness when the vehicle body is turned down when moving from straight running to turning. Therefore, when the folded portions 6b and 6b are hollow, it is preferable that the overlap width Wa is in the range of 15% to 35% of the band width W1.

  Further, in order to improve the steering stability at a high level, it is also necessary to secure a tread stiffness having a magnitude corresponding to the aforementioned side stiffness in a well-balanced manner. However, in the tire 1, although the tread rigidity can be increased to some extent by the overlapping portion 20, it is not sufficient, and it is difficult to ensure satisfactory steering stability.

  Therefore, in the present invention, a belt layer 9 is provided between the band ply 7A and the main body portion 6a of the carcass 6 to ensure the tread rigidity commensurate with the aforementioned side rigidity.

  Specifically, the belt layer 9 is formed of one or more belt plies 9A, in this example, one belt ply 9A in which belt cords are arranged at an angle γ of 45 to 87 ° with respect to the tire circumferential direction. When the belt ply 9A is one, the inclination direction of the belt cord is different from the inclination direction of the carcass cord in the main body portion 6a. The cross arrangement of the belt cord and the carcass cord effectively increases the tread rigidity in a well-balanced manner, and improves the steering stability including the transient characteristics. When the belt layer 9 is composed of two belt plies, the inclination direction of the belt cord is made different between the two belt plies.

Here, when the belt cord angle γ exceeds 87 °, the tread rigidity is not sufficiently ensured, and satisfactory steering stability cannot be obtained. If the angle is less than 45 °, the tread rigidity is excessively increased, the cornering power is excessively increased, and the high-speed stability is deteriorated, for example, causing vibration and vibration to the vehicle body. Accordingly, the upper limit value of the belt cord angle γ is preferably 85 ° or less, more preferably 80 ° or less, and the lower limit value is preferably 55 ° or more, more preferably 67 ° or more. Moreover, if the difference between the cord angles α and γ is too large, the carcass 6 and the belt layer 9 cannot be shaped into a toroid at a time when creating the first cover in the raw tire forming process, which may impair the productivity. Invite. Therefore, it is preferable to regulate the difference | α−γ | between the cord angles α and γ to 20 ° or less, and further to 10 ° or less.

  Further, in the belt layer 9, the belt width W2 in the tire axial direction along the belt layer 9 needs to be 80 to 98% of the tread width TW. If less than 80%, the tread rigidity in the tread shoulder region is required. And the turning performance is reduced. On the other hand, if the belt width W2 is too wide, the flexible region of the sidewall portion 3 is reduced, leading to a decrease in ride comfort, and a stress acting on the outer end of the belt layer is increased, which is disadvantageous for durability. Therefore, the belt width W2 is 98% or less of the tread width TW, and is preferably set smaller than the band width W1. When the band layer 7 and the belt layer 9 are each formed of a plurality of plies, the widest ply width is defined as the band width W1 and the belt width W2.

Next, another embodiment (reference example) of the motorcycle tire 1 is illustrated in FIGS. In the tire 1 of the reference example, the turn-up portion 6b of the carcass 6 has an overlap portion 21 where the turn-up portions 6b and 6b overlap each other in the radial direction inside and outside by crossing the tire equator plane Co and outside in the tire axial direction. Forming.

  However, at this time, it is preferable that the overlapping width Wb of the overlapping portion 21 along the carcass 6 is in the range of 0% to 25% or less, or in the range of 60 to 90% of the tread width TW. This is because if the overlap width Wb is larger than 25% and smaller than 60% of the tread width TW, the overlap portion is located in a region where the tread surface comes into contact with the ground when moving from straight running to turning. Because the outer end of 21 appears as a rigidity step, the rigidity balance in the tread surface is impaired, and the transitional characteristics are deteriorated, for example, the smoothness of the vehicle body collapse is impaired in the transition from straight running to turning. is there. The reason why the overlap width Wb is 90% or less of the tread width TW is that if it exceeds 90%, the stress acting on the outer end of the overlap portion increases, which is disadvantageous to durability. It is preferable to set the width smaller than the band width W1 and further smaller than the belt width W2.

In the tire of the reference example, substantially the same configuration as that of the tire of the first embodiment can be adopted except that the carcass ply has the overlapping portion 21. Further, as in this example, it is preferable from the viewpoint of productivity that the belt layer 9 is formed between the body portion 6a and the folded portion 6b of the carcass 6, but the belt layer 9 is folded with the band layer 7 as required. It can also be formed between the portion 6b.

  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.

The tire for a motorcycle (tire size 120 / 70R17) of the first embodiment having the structure of FIG. 1 and the specification of Table 1 and the tire for a motorcycle of the reference example having the structure of FIG. Each of the tire sizes 120 / 70R17) was prototyped, and the steering stability (high-speed stability, turning performance, transient characteristics), riding comfort, and grip performance of the sample tire were evaluated by an actual vehicle running test. Specifications other than those described in Tables 1 and 2 are substantially the same as described in Table 3.

(1) Actual vehicle running test:
The tire is mounted on the front wheel of a large motorcycle (1000CC) under the conditions of a rim (MT3.50 × 17) and internal pressure (250 kPa), running on a dry asphalt tire test course, and the steering stability at that time ( High-speed stability, turning performance, transient characteristics), riding comfort, and grip performance were evaluated by a five-point method based on driver's sensory evaluation. A larger index is better.

In the rear wheel,
・ Tire size: 190 / 50R17,
Carcass: Number of plies (2 sheets), cord angle α (+ 72 ° / −72 °), cord (nylon, 940 dtex / 2),
Band layer: cord angle (0 °, spiral winding), band width W1 (198 mm),
A commercially available tire having the following specifications was used under the conditions of a rim (MT 6.00 × 17) and an internal pressure (290 kPa).

  As shown in Tables 1 and 2, it can be confirmed that the tires of the examples can exhibit excellent ride comfort comparable to that of Comparative Example 1 while ensuring excellent steering stability equivalent to or higher than that of Comparative Example 2. .

1 is a cross-sectional view showing a first embodiment of a motorcycle tire of the present invention. FIG. 2 is a diagram schematically illustrating the arrangement of the carcass cord, band cord, and belt cord of the tire of FIG. It is sectional drawing of the tire for motorcycles of a reference example . FIG. 4 is a diagram schematically showing the arrangement of the carcass cord, band cord, and belt cord of the tire of FIG. It is sectional drawing explaining a conventional tire.

Explanation of symbols

2 tread portion 2S tread surface 3 side wall portion 4 bead portion 5 bead core 6 carcass 6A carcass ply 6a body portion 6b folded portion 7 band layer 7A band ply 9 belt layer 9A belt ply 20 overlap portion 21 overlap portion

Claims (4)

A carcass provided with a series of folded portions that are folded from the inner side to the outer side in the tire axial direction around the bead core in the main body portion that extends from the tread portion to the bead core through the sidewall portion, and the inside of the tread portion and the A motorcycle tire having a band layer made of a band ply arranged outside the carcass and spirally wound with a band cord at an angle of 5 degrees or less with respect to the tire circumferential direction;
The carcass is composed of one carcass ply in which carcass cords are arranged at an angle of 65 to 87 ° with respect to the tire circumferential direction, and the folded portion has an overlapping portion that overlaps the band layer on the inside in the radial direction. And have a break
Between the band ply and the carcass main body, a belt layer made of a belt ply in which a belt cord is arranged at an angle of 45 to 87 ° with respect to the tire circumferential direction is provided.
Moreover, the band width W1 along the band layer of the band layer is 80 to 98% of the tread width TW along the tread surface of the tread surface, and the belt width W2 along the belt layer of the belt layer is the tread width TW. 80-98% of
The folded portion of the carcass is interrupted on the outer side in the tire axial direction without crossing the tire equatorial plane, and the overlapping width Wa along the carcass of the overlapping portion is 15 to 35% of the band width W1. Motorcycle tires to be used.   The motorcycle tire according to claim 1, wherein the belt layer is formed of a single belt ply, and a direction of inclination of the belt cord is different from a direction of inclination of the carcass cord in the main body.   2. The motorcycle tire according to claim 1, wherein the belt layer includes two belt plies, and the inclination direction of the belt cord is different between the two belt plies.   The motorcycle tire according to claim 1, wherein the belt layer is disposed between a main body portion and a folded portion of the carcass.

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