JP5993123B2 - Motorcycle tires - Google Patents

Description

  The present invention relates to a motorcycle tire that can significantly improve turning performance.

  In recent years, in motorcycle tires, a jointless ply in which a belt cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction is used for a belt layer disposed inside a tread portion. (See Patent Document 1 below). Such a jointless ply can reduce the surface rigidity compared with a conventional cut end ply in which belt cords are crossed and overlapped with each other, and can improve the riding comfort.

JP 2006-15830 A

  However, the jointless ply as described above has a problem in that the lateral force during turning is smaller than that of the cut end ply, and the turning performance cannot be sufficiently improved.

  Moreover, in order to obtain the lateral force at the time of turning, it is conceivable to embed a reinforcing member in the bead part or the sidewall part, but such partial strengthening of the tire deteriorates the disturbance absorption, There was also the problem of reducing the transient characteristics during turning.

  The present invention has been devised in view of the actual situation as described above. The outer end of the folded portion of the folded carcass ply is terminated inside the belt layer formed of the inner side of the tread portion and the jointless ply. A motorcycle tire that can significantly improve turning performance based on limiting the overlap length between the belt portion and the belt layer and the shortest length between the belt cord and the carcass cord to a predetermined range. The main purpose is to provide.

The invention according to claim 1 of the present invention includes a main body part extending from the tread part through the sidewall part to the bead core of the bead part, and a turn-up part connected to the main body part and folded around the bead core from the inner side to the outer side in the tire axial direction. carcass comprising a folded carcass ply Ru comprising bets, and inward radially outer tread portion of the carcass, jointless wound belt cords spirally at an angle of less than 5 degrees with respect to the tire circumferential direction A motorcycle tire having a belt layer made of a ply , wherein the folded carcass ply includes an inner carcass ply disposed on an inner side of the tire equator and an outer carcass ply disposed on an outer side of the inner carcass ply. The outer end of the folded portion of the inner carcass ply and the outer end of the folded portion of the outer carcass ply are: The inner length of the tread portion and the inner side of the belt layer, the overlap length from the outer end of the folded portion of the inner carcass ply to the outer end of the belt layer in the tire axial direction, and the outer side The overlap length of the carcass ply is 20 to 50% of a half width of the tread, and the outer end of the outer carcass ply terminates outside the outer end of the inner carcass ply in the tire axial direction. The length in the tire axial direction between the outer end of the carcass ply and the outer end of the outer carcass ply is 5 to 20% of the half width of the tread , and the belt cord of the belt layer and the belt layer The shortest length between the cord and the carcass cord of the turn-up portion of the turn-up carcass ply adjacent to the turn-around carcass ply is 0.2 to 0.8 mm.

Further, an invention according to claim 2, wherein the belt cord is a motorcycle tire according to claim 1 which is an aramid fiber cord or steel cord.

The invention according to claim 3 is the motorcycle tire according to claim 1 or 2 , wherein the carcass cord is an organic fiber cord made of nylon, PET, PEN, aramid, or rayon.

  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".

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

  A motorcycle tire according to the present invention includes a main body part that extends from a tread part through a sidewall part to a bead core of a bead part, and a folded part that is connected to the main body part and is turned around from the inner side to the outer side in the tire axial direction. A carcass including at least one folded carcass ply, and a jointless in which a belt cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction on the outer side in the tire radial direction and on the inner side of the tread portion of the carcass It has a belt layer made of ply. Such a jointless ply can have a lower surface rigidity than a conventional cut-end ply, and can improve riding comfort.

  In addition, at least one folded carcass ply has an outer end of the folded portion that terminates inward of the tread portion and inside the belt layer, and an overlap length between the folded portion and the belt layer is determined by the tread. It is set to 20 to 50% of the half width.

  Such a folded carcass ply can increase the lateral force at the time of turning by making the carcass cord cross the belt cord in a wide range on the tread end side that is mainly grounded at the time of turning, and can improve the turning performance. In addition, the folded carcass ply is not disposed on the tire equator side, which is mainly grounded when traveling straight, and does not deteriorate the riding comfort.

  Furthermore, the shortest length between the cords of the belt cord of the belt layer and the carcass cord of the folded portion of the folded carcass ply adjacent to the belt layer is set to 0.2 to 0.8 mm. In this way, the carcass cord of the folded carcass ply and the belt cord are brought closer to each other and their restraining force is increased to further increase the lateral force during turning and greatly improve turning performance. Yes.

1 is a cross-sectional view showing a motorcycle tire of the present embodiment. It is an expanded view which shows the folding | turning part and belt layer of a carcass ply. It is AA sectional drawing of FIG. It is sectional drawing which shows the tire for motorcycles of other embodiment. FIG. 5 is a development view showing a folded portion and a belt layer of the carcass ply of FIG. 4. (A), (b), (c) is sectional drawing which shows the tire for motorcycles of Comparative Examples 1-3.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a motorcycle tire (hereinafter sometimes simply referred to as “tire”) 1 according to the present embodiment is a carcass extending from a tread portion 2 to a bead core 5 of a bead portion 4 through a sidewall portion 3. 6 and a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and on the inner side of the tread portion 2.

  Further, the tire 1 has an outer surface 2S between the tread ends 2t and 2t of the tread portion 2 in a circular arc shape protruding outward in the tire radial direction so that a sufficient contact area can be obtained even when turning with a large camber angle. In addition to being curved, the tread width TW, which is the distance in the tire axial direction between the tread ends 2t and 2t, forms the maximum tire width.

  The carcass 6 includes a main body portion 6a that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a turn-back portion that is connected to the main body portion 6a and is turned around from the inner side to the outer side in the tire axial direction. 6b, and in this embodiment, it is constituted by one folded carcass ply 6A. A bead apex 8 made of hard rubber is disposed between the body portion 6a and the folded portion 6b of the folded carcass ply 6A.

Further, as shown in FIG. 2, the folded carcass ply 6A is arranged such that the carcass cord 11 is inclined at an angle θ1 of, for example, 65 to 90 degrees with respect to the tire circumferential direction. The carcass cord 11 is preferably an organic fiber cord made of nylon, PET, PEN, aramid, or rayon, which is excellent in flexibility and bending fatigue resistance.

  The belt layer 7 is composed of one layer of a jointless ply 7A in which one or a plurality of belt cords 12 covered with rubber are spirally wound at an angle θ2 of 5 degrees or less with respect to the tire circumferential direction.

  Such a jointless ply 7A can allow local deformation of the belt layer 7 as compared with a conventional cut end ply (not shown) in which belt cords are crossed and overlapped with each other. Therefore, the jointless ply 7A can exhibit good disturbance absorption and can improve riding comfort.

  In order to improve the high-speed stability performance and turning performance while maintaining the above-mentioned riding comfort, the width W1 (shown in FIG. 1) of the jointless ply 7A in the tire axial direction is 85 to 95% of the tread width TW. Degree is desirable. From the same viewpoint, the belt cord 12 is preferably an aramid fiber cord or a steel cord having a high tensile strength.

  As shown in FIGS. 1 and 2, the folded carcass ply 6 </ b> A of the present embodiment has an outer end 6 be of the folded portion 6 b that terminates inside the tread portion 2 and inside the belt layer 7.

  In such a folded carcass ply 6A, the carcass cord 11 of the folded portion 6b crosses the belt cord 12 on the tread end 2t side that is mainly grounded during turning, and the binding force between the folded portion 6b and the belt layer 7 is increased. Yes. Therefore, the folded carcass ply 6A can increase the lateral force at the time of turning, and can improve the turning performance.

  Furthermore, the overlap length L1 between the folded portion 6b and the belt layer 7 is set to 20 to 50% of the tread half width 0.5 TW. Here, the overlap length L1 is a distance in the tire axial direction between the outer end 6be of the folded portion 6b of the folded carcass ply 6A and the outer end 7e of the belt layer 7 in the tire axial direction.

  Therefore, the folded carcass ply 6A can cross the carcass cord 11 with the belt cord 12 in a wide range on the tread end 2t side, and can surely increase the restraining force by the folded portion 6b and the belt layer 7. In addition, the turn-up portion 6b of the turn-up carcass ply 6A is not arranged on the tire equator C side, which is mainly grounded when going straight, and thus does not deteriorate the riding comfort.

  If the ratio L1 / 0.5TW between the overlap length L1 and the tread half width 0.5 TW is less than 20%, the lateral force during turning may not be sufficiently increased. On the contrary, if the ratio L1 / 0.5TW exceeds 50%, the folded carcass ply 6A is disposed on the tire equator C side, which may deteriorate the riding comfort. From such a viewpoint, the ratio L1 / 0.5TW is more preferably 30% or more, and more preferably 45% or less.

  Further, as shown in FIG. 3, the shortest length L2 between the cords of the belt cord 12 of the belt layer 7 and the carcass cord 11 of the folded portion 6b of the folded carcass ply 6A adjacent to the belt layer 7c is 0. Set to 2 to 0.8 mm.

  Thus, in the present embodiment, the carcass cord 11 and the belt cord 12 of the folded carcass ply 6A are brought closer to each other than before, and the restraining force is further increased to further increase the lateral force during turning. The turning performance can be greatly improved.

  If the shortest length L2 is less than 0.2 mm, there is a risk that durability will be lowered, such as a large friction between the carcass cord 11 and the belt cord 12 and damage such as breakage. On the contrary, if the shortest length L2 exceeds 0.8 mm, the carcass cord 11 and the belt cord 12 are excessively separated, and there is a possibility that their restraining force cannot be sufficiently increased. From such a viewpoint, the shortest length L2 is more preferably 0.3 mm or more, and more preferably 0.5 mm or less.

FIG. 4 shows a tire 1 according to another embodiment of the present invention.
In this embodiment, the folded carcass ply 6 </ b> A includes, on the tire equator C, an inner carcass ply 15 disposed on the inner side in the tire radial direction and an outer carcass ply 16 disposed on the outer side of the inner carcass ply 15. These inner and outer carcass plies 15 and 16 include main body portions 15a and 16a and folded portions 15b and 16b, respectively.

  Further, as shown in FIG. 5, the inner carcass ply 15 and the outer carcass ply 16 of the present embodiment are inclined with respect to the tire equator C at an angle θ3 of 65 to 90 degrees, for example. And are inclined in opposite directions.

  As shown in FIGS. 4 and 5, the inner carcass ply 15 has an outer end 15be of the folded portion 15b that terminates inward of the tread portion 2 and on the inner side in the tire radial direction of the belt layer 7, and the belt layer. 7 is set to 20 to 50% of the tread half width 0.5 TW.

  Such a folded-back portion 15b of the inner carcass ply 15 can be adjacent to the belt layer 7 so that the carcass cord 19 intersects the belt cord 12 of the belt layer 7 and can improve lateral force during turning.

  The shortest length (not shown) between the carcass cord 19 of the folded portion 15b of the inner carcass ply 15 and the belt cord 12 of the belt layer 7 is also set to 0.2 to 0.8 mm. The lateral force of can be further improved.

  Similarly to the inner carcass ply 15, the outer end 16 be of the folded portion 16 b of the outer carcass ply 16 of the present embodiment also terminates inside the tread portion 2, the belt layer 7, and the folded portion 15 b of the inner carcass ply 15.

  The folded portion 16b of the outer carcass ply 16 can intersect the carcass cord 20 with the carcass cord 19 and the belt cord 12 of the folded portion 15b of the inner carcass ply 15 on the tread end 2t side, The restraining force between the folded portion 15b and the belt layer 7 can be further increased.

  Furthermore, the overlap length L4 between the folded portion 16b of the outer carcass ply 16 and the belt layer 7 is set to 20 to 50% of the tread half width 0.5 TW. As a result, the folded-back portion 16b of the outer carcass ply 16 can cross the carcass cord 20 and the carcass cord 19 of the inner carcass ply 15 over a wide range on the tread end 2t side, thereby further ensuring lateral force during turning. Can be increased.

  The outer end 16be of the outer carcass ply 16 is preferably terminated with a position shift in the tire axial direction from the outer end 15be of the inner carcass ply 15. Thus, the inner carcass ply 15 and the outer carcass ply 16 can gradually increase the tread rigidity from the tire equator C side to the tread end 2t side, and can improve the transient characteristics during turning.

  Further, it is desirable that the outer end 16be of the outer carcass ply 16 terminates on the outer side in the tire axial direction than the outer end 15be of the inner carcass ply 15. Thereby, since the overlap length L1 of the inner carcass ply 15 closest to the belt layer 7 is ensured, the transient characteristics can be improved while improving the turning performance.

  In order to effectively exhibit such an action, the ratio between the outer end 15be of the inner carcass ply 15, the outer end 16be of the outer carcass ply 16, the length L5 in the tire axial direction, and the tread half width 0.5TW. L5 / 0.5TW is desirably 5 to 20%.

  If the ratio L5 / 0.5TW is less than 5%, the transient characteristics may not be sufficiently improved. On the contrary, if the L5 / 0.5TW exceeds 20%, the folded portion 16b of the outer carcass ply 16 cannot be sufficiently overlapped with the belt layer 7 and the turning performance may not be sufficiently improved. . From such a viewpoint, the ratio L5 / 0.5TW is more preferably 10% or more, and more preferably 15% 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.

Rear tires for motorcycles having the basic structure shown in FIG. 1 or 4 and having the carcass ply as shown in Table 1 were manufactured and their performances were tested. For comparison, a tire (Comparative Example 1) including two carcass plies whose outer ends of the folded portion shown in FIG. 6 (a) terminate at the sidewall portion, and the folded portion shown in FIG. 6 (b). A tire including one carcass ply whose outer end terminates at a sidewall portion (Comparative Example 2), a tire in which a reinforcing layer is disposed between the belt layer and the carcass ply shown in FIG. Comparative example 3) was tested in the same manner. The common specifications are as follows.
tire size:
Front wheel: 120 / 70ZR17
Rear wheel: 180 / 55ZR17
Rim size:
Front wheel: MT3.50 × 17
Rear wheel: MT5.50x17
Tread width TW: 180mm
Tread half width 0.5TWe: 90mm
Carcass:
Folded carcass ply:
Carcass cord angle θ1: 90 degrees
Carcass cord end: 40 / 5cm
Inner carcass ply and outer carcass ply:
Carcass cord angle θ3: 80 degrees
Carcass cord end: 40 / 5cm
Belt layer:
Number of jointless plies: 1
Jointless ply width W1: 168mm
Ratio W1 / TW: 93%
Belt cord cord material: Steel
Belt cord angle θ2: 0 degrees Reinforcement layer:
Cord material: Nylon
Code structure: 2100dtex / 2
An angle of 45 degrees with respect to the tire circumferential direction of the reinforcing cord The test method is as follows.

<Disturbance absorption, turning performance, transient characteristics, ride comfort>
Each test tire is assembled on the rim, filled with an internal pressure of 290 kPa, mounted on the rear wheel of a motorcycle with a displacement of 600 cc, and "disturbance absorption", "turning" when driving around a dry asphalt road test course Performance, "transient characteristics", and "riding comfort" were evaluated by a 10-point method based on driver's sensory evaluation. The larger the value, the better.

<Durability>
Each test tire is assembled on the rim, filled with an internal pressure of 290 kPa, and traveled at a speed of 80 km / h at a load of 3.58 kN using a drum testing machine until the tire is damaged. Was measured. Evaluation is indicated by an index with Comparative Example 1 being 100, and the larger the value, the better.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the motorcycle tire of the example can greatly improve the turning performance, and can improve the disturbance absorption, the transient characteristics, and the riding comfort.

1 Motorcycle Tire 6 Carcass 6A Folded Carcass Ply 7 Belt Layer 7A Jointless Ply 11 Carcass Cord 12 Belt Cord

Claims (3)

Carcass comprising a main body portion reaching the bead core of a bead portion through a sidewall portion from a tread portion, a folded carcass ply Ru comprising a folded portion which is folded outwardly around the bead cores continuous with the body portion from the axially inside, and A motorcycle tire having a belt layer composed of a jointless ply in which a belt cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction on the outer side in the tire radial direction of the carcass and in the tread portion. There,
The folded carcass ply is composed of an inner carcass ply disposed on the inner side in the tire equator and an outer carcass ply disposed on the outer side of the inner carcass ply,
The outer end of the folded portion of the inner carcass ply and the outer end of the folded portion of the outer carcass ply terminate inside the tread portion and inside the belt layer,
The overlap length from the outer end of the folded portion of the inner carcass ply to the outer end of the belt layer in the tire axial direction, and the overlap length of the outer carcass ply are 20 to 50% of the tread half width. And
The outer end of the outer carcass ply terminates on the outer side in the tire axial direction than the outer end of the inner carcass ply,
The length in the tire axial direction between the outer end of the inner carcass ply and the outer end of the outer carcass ply is 5 to 20% of the half width of the tread,
The minimum length between the cords of the belt cord of the belt layer and the carcass cord of the folded portion of the folded carcass ply adjacent to the belt layer is 0.2 to 0.8 mm. Tires for motorcycles. The motorcycle tire according to claim 1, wherein the belt cord is an aramid fiber cord or a steel cord. The motorcycle tire according to claim 1 or 2, wherein the carcass cord is an organic fiber cord made of nylon, PET, PEN, aramid, or rayon.

Images