JP2020093659A - Pneumatic tire for motor cycle - Google Patents

Abstract

To provide a pneumatic tire for a motor cycle capable of maintaining stability during travel and improving gap absorption performance.SOLUTION: There is provided a pneumatic tire 1 for a motor cycle with a carcass 6. The carcass includes a carcass ply 9, and the carcass ply comprises: a main body part 10 extending between bead cores 5 which are embedded in a bead part 4; and a pair of windup parts 11 which are folded outward from an inner side of a tire axial direction around the bead core. The windup part has a windup end 11e on a tire side K, and an angle of the main body part that overlaps the windup part relative to a carcass cord in a tire circumferential direction is larger than an angle of a main body part outer region 10A positioned on an outer side of the windup end in the tire radial direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire for a motorcycle having a carcass.

Patent Document 1 below describes a tire for a motorcycle including a folded carcass layer having a crown portion and side portions. The crown portion is symmetrical about the equatorial plane of the tire and has a substantially constant angle reinforcer equal to at least 65° with the circumferential direction. The lateral portion is provided on the inner side in the tire radial direction of the crown portion and has an angle smaller than the angle of the reinforcer of the crown portion. The reinforcement is made of a fibrous material, preferably polyester or nylon.

Japanese Patent No. 6195615

Since the tire as described above has high rigidity as a whole, there is a problem that the gap absorption performance is low.

The present invention has been made in view of the above problems, and provides a pneumatic tire for a motorcycle, which can improve the gap absorption performance while maintaining the stable performance during traveling. Its main purpose is.

The present invention is a pneumatic tire for a motorcycle having a carcass, wherein the carcass includes a carcass ply that is a layer of a carcass cord, and the carcass ply extends between bead cores embedded in a pair of bead portions. The carcass cord has a main body portion and a pair of winding portions that are folded back from the inner side in the tire axial direction around the respective bead cores, and the pair of winding portions each have a winding end on the tire side. With respect to the angle with respect to the tire circumferential direction, each of the pair of hoisting portions is larger than a main body portion outer region located outside the hoisting end of the main body portion in the tire radial direction.

The pneumatic tire for a motorcycle according to the present invention is such that, with respect to an angle of the carcass cord with respect to the tire circumferential direction, a main body portion inner region located on the tire radial direction inner side of the winding end of the main body portion is the main body portion outer region. It is desirable to be larger than.

In the pneumatic tire for a motorcycle according to the present invention, the difference between the angle of the pair of winding portions with respect to the tire circumferential direction of the carcass cord and the angle of the carcass cord in the main body outer region is 5 degrees or more. Is desirable.

In the pneumatic tire for a motorcycle according to the present invention, the difference is preferably 15 degrees or less.

In the pneumatic tire for a motorcycle according to the present invention, the hoisting end has a tire radial direction outer side from a bead base line, and a tire radial direction distance between a carcass maximum width position and the bead base line is 1.5 times or more. Is also preferably on the inner side in the tire radial direction.

In the pneumatic tire for a motorcycle according to the present invention, it is preferable that a belt layer is arranged on the tread portion on the outer side in the tire radial direction of the carcass.

In the pneumatic tire for a motorcycle according to the present invention, it is preferable that an outer end of the belt layer in the tire axial direction is outside the carcass maximum width position in the tire radial direction.

In the pneumatic tire for a motorcycle according to the present invention, a distance in the tire radial direction between the winding-up end and an outer end of the belt layer in the tire axial direction is preferably 10 to 20 mm.

In the pneumatic tire for a motorcycle according to the present invention, it is desirable that an angle of the pair of hoisting portions with respect to a tire circumferential direction of the carcass cord is 70 to 90 degrees.

In the pneumatic tire for a motorcycle according to the present invention, it is desirable that an angle of the outer region of the main body portion with respect to a tire circumferential direction of the carcass cord is 65 to 85 degrees.

The pneumatic tire for a motorcycle according to the present invention is, with respect to an angle with respect to the tire circumferential direction of the carcass cord, in a body portion inner region located on the tire radial direction inner side of the winding end of the body portion, in a tire radial direction inner side. It is desirable to increase gradually.

The pneumatic tire for a motorcycle of the present invention includes a carcass ply having a main body portion extending between the bead cores, and a pair of winding portions that are folded back from the inner side in the tire axial direction around the bead cores. Each of the pair of hoisting portions has a hoisting end on the tire side. Regarding the angle of the carcass cord with respect to the tire circumferential direction, the hoisting portion is larger than the main body portion outer region located outside the hoisting end of the body portion in the tire radial direction. As described above, in the winding portion, the angle of the carcass cord is formed to be relatively large. As a result, the rigidity of the tire side is appropriately reduced, and the gap absorption performance is improved. Further, the angle of the outer region of the main body is formed to be relatively small. As a result, the portion on the outer side in the tire radial direction with respect to the tire side has high rigidity, so that stable performance during traveling is maintained.

Therefore, the pneumatic tire for a motorcycle of the present invention exhibits excellent gap absorption performance while maintaining stable performance during traveling.

It is a tire meridian sectional view of the motorcycle pneumatic tire of the present invention. It is a development view of the carcass ply of FIG. It is a development view of the carcass ply of other embodiment.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view of a tire meridian including a tire rotation axis (not shown) in a normal state of a pneumatic tire for a motorcycle (hereinafter, sometimes simply referred to as “tire”) 1 of the present embodiment. FIG. 1 shows a tire 1 suitable for on-road racing, for example. However, the tire 1 of the present invention is not limited to such an aspect, and is used in various pneumatic tires 1 for motorcycles.

The "regular state" is an unloaded state in which the tire 1 is assembled on a regular rim (not shown) and filled with a regular internal pressure. In the present specification, the dimensions and the like of each part of the tire 1 are values specified in a normal state unless otherwise specified.

The "regular rim" is a rim that is defined for each tire in the standard system including the standard on which the tire 1 is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, ETRTO is "Measuring Rim".

"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 1 is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD" LIMITS AT VARIOUS COLD INFLATION PRESSURES Maximum value, ETRTO is "INFLATION PRESSURE".

In the tire 1 of the present embodiment, the tread contact surface 2a between the tread ends 2t and 2t of the tread portion 2 is convex outward in the tire radial direction so that a sufficient contact area can be obtained even during turning with a large camber angle. It curves and extends in an arc shape. The tire axial distance between the tread ends 2t, 2t is the tread width TW, which is the maximum tire width.

The tire 1 includes a toroidal carcass 6 extending from the tread portion 2 to the bead portion 4 through the sidewall portion 3. A bead core 5 is embedded in the bead portion 4 of this embodiment.

The carcass 6 includes a carcass ply 9 which is a layer of the carcass cord 8 (shown in FIG. 2). The carcass 6 is formed by one carcass ply 9 in this embodiment. This suppresses an excessive increase in the rigidity of the tire 1. As the carcass cord 8, for example, an organic fiber cord such as nylon, polyester or rayon is suitable.

The carcass ply 9 of the present embodiment has a body portion 10 extending between the pair of bead cores 5 and 5, and a pair of winding portions 11 and 11 folded back from the inner side in the tire axial direction around the respective bead cores 5. doing.

The hoisting portion 11 of the present embodiment has hoisting ends 11e on the tire side K, respectively. In the present specification, the tire side K refers to a region extending from the sidewall portion 3 to the bead portion 4.

In the present embodiment, the main body portion 10 includes a main body portion outer area 10A located on the tire radial direction outside of the hoisting end 11e and a pair of main body portion inner areas 10B, 10B located on the tire radial direction inner side of the hoisting end 11e. Includes and. Since the winding end 11e is located on the tire side K, the main portion of the main body outer region 10A is formed in the tread portion 2 in this embodiment.

FIG. 2 is a development view of the carcass ply 9. As shown in FIG. 2, the winding portion 11 is larger than the main body outer region 10A with respect to the angle θ of the carcass cord 8 with respect to the tire circumferential direction. In this way, the winding portion 11 is formed such that the angle θ2 of the carcass cord 8 is relatively large. As a result, the rigidity of the tire side K is appropriately reduced, and the gap absorption performance is improved. Further, the angle θ1 of the carcass cord 8 in the main body outer region 10A is formed to be relatively small. As a result, the tread portion 2, which is a portion on the outer side in the tire radial direction with respect to the tire side K, has high rigidity, and therefore stability during traveling is maintained. Therefore, the tire 1 of the present embodiment exhibits good gap absorption performance while maintaining stable performance during traveling.

It is desirable that the difference between the angle θ2 of the carcass cord 8 of the winding portion 11 with respect to the tire circumferential direction and the angle θ1 of the carcass cord 8 of the main body outer region 10A is 5 degrees or more. When the difference between the angle θ2 of the hoisting portion 11 and the angle θ1 of the main body outer region 10A is less than 5 degrees, the difference in rigidity between the tread portion 2 and the tire side K becomes small, and the gap absorbing performance is improved, or , It may not be possible to maintain stable performance during driving.

On the contrary, when the difference between the angle θ2 of the winding portion 11 and the angle θ1 of the main body outer region 10A exceeds 15 degrees, the bending of the carcass cord 8 becomes large and its rigidity becomes small, so that the stability performance during traveling is improved. It may decrease. Therefore, it is desirable that the difference between the angle θ2 of the winding portion 11 and the angle θ1 of the main body outer region 10A is 15 degrees or less.

With respect to the angle θ of the carcass cord 8 with respect to the tire circumferential direction, it is desirable that the main body inside region 10B be larger than the main body outside region 10A. As a result, the effect of keeping the rigidity of the tire side K small is enhanced, and the gap absorption performance is further enhanced.

Regarding the angle θ of the carcass cord 8, in the main body inner region 10B, for example, it gradually increases toward the tire radial inner side. The main body portion inner side region 10B of the present embodiment includes a first region 12A in which the angle θ3 of the carcass cord 8 gradually increases inward in the tire radial direction, and a second region 12B in which the angle θ3 of the carcass cord 8 is constant. Is formed by. In the second region 12B, for example, the angle θ3 is the same as the angle θ2 of the winding portion 11.

The angle θ1 of the main body outer region 10A is preferably 65 to 85 degrees. When the angle θ1 of the main body outer region 10A exceeds 85 degrees, the rigidity of the tread portion 2 becomes small, which may deteriorate the stability performance during traveling. When the angle θ1 of the main body outer region 10A is less than 80 degrees, the inclination of the carcass cord 8 of the main body outer region 10A with respect to the tire axial direction becomes large, the directionality becomes obvious, and the stability performance during traveling may deteriorate. is there.

The angle θ2 of the winding portion 11 is preferably 70 to 90 degrees. If the angle θ2 of the winding portion 11 is less than 85 degrees, the rigidity of the tire side K may be increased and the gap absorption performance may be deteriorated.

As shown in FIG. 1, the winding-up end 11e is more than 1.5 times the tire radial direction distance La between the carcass maximum width position M and the bead base line BL toward the tire radial direction outer side from the bead base line BL. It is desirable to be on the inner side in the tire radial direction. As a result, excessive tread rigidity is suppressed, and the feeling of contact with the ground when turning at a large camber angle is improved. In FIG. 1, the distance in the tire radial direction between the winding end 11e and the bead base line BL is indicated by Lt.

In the present embodiment, the hoisting end 11e is located inside the carcass maximum width position M in the tire radial direction. As a result, the increase in rigidity near the carcass maximum width position M is suppressed, and the strain due to the load during running of the tire 1 can be concentrated near the carcass maximum width position M. As a result, the flexure during traveling can be reduced, and the stable performance during traveling can be maintained high. When the distance L1 in the tire radial direction between the hoisting end 11e and the carcass maximum width position M is large, the rigidity of the sidewall portion 3 is significantly reduced, and the stability performance during traveling may be deteriorated. From such a viewpoint, the distance L1 between the winding end 11e and the carcass maximum width position M is preferably about 2% to 5% of the tire cross-section height H. The carcass maximum width position M is a position where the carcass 6 projects most outward in the tire axial direction. The tire cross-section height H is the distance in the tire radial direction from the bead base line BL, which is a tire axial direction line passing through the position of the rim diameter, to the tread contact surface 2a on the tire equator C.

In the tread portion 2 of the present embodiment, a belt layer 7 is arranged outside the carcass 6 in the tire radial direction. The belt layer 7 exerts a hoop effect and enhances stability performance during traveling.

The belt layer 7 includes at least one belt cord (not shown) arranged at, for example, about 15 to 30 degrees in the tire circumferential direction. In the present embodiment, two belt plies 7A and 7B are provided inside and outside in the tire radial direction. Composed. The belt plies 7A and 7B are stacked in such a manner that belt cords cross each other between the plies. As the belt cord, a highly elastic organic fiber cord such as rayon or aromatic polyamide or a steel cord is suitable.

In the present embodiment, the outer belt ply 7B is formed wider than the inner belt ply 7A. In order to maintain high stability during running, the width Wa of the widest belt ply (the outer belt ply 7B in this embodiment) in the tire axial direction is set to be 85% or more of the tread width TW. desirable. The inner belt ply 7A may be formed wider than the outer belt ply 7B.

An outer end of the belt layer 7 in the tire axial direction (in the present embodiment, an outer end of the outer belt ply 7B) 7e is, for example, outside the carcass maximum width position M in the tire radial direction. As a result, in the present embodiment, the carcass maximum width position M is located between the outer end 7e of the belt layer 7 and the winding end 11e, and the belt plies 7A, 7B and the carcass ply 9 are not overlapped. The protruding region 14 formed by the carcass ply 9 is formed. Also in the projecting region 14, the angle θ (θ1) of the carcass cord 8 is smaller than that of the winding portion 11, so that the carcass cord 8 has high rigidity. Therefore, the rigidity difference between the portion of the outer region 10A of the main body portion in contact with the belt layer 7 and the protruding region 14 is kept small, so that the stability performance during traveling is further improved.

In order to effectively exhibit the above-mentioned action, the distance L2 in the tire radial direction between the winding end 11e and the outer end 7e of the belt layer 7 is preferably 10 to 20 mm.

FIG. 3 is a development view of a carcass ply 9 according to another embodiment. The same components as those of the present embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 3, in this embodiment, the angle θ3 of the carcass cord 8 in the main body inner region 10B is the same as the angle θ2 of the carcass cord 8 of the hoisting portion 11, and is formed to be constant. In such a mode, since the rigidity of the tire side K is reduced to an appropriate degree, the gap absorption performance is improved.

In this embodiment, in the main body outer region 10A, an inner region 15A in which the angle θ1 of the carcass cord 8 is constant and a pair of outer regions 15B and 15B in which the angle θ1 gradually increases toward the main body inner region 10B. Is formed by. In the tire 1 of this embodiment, the outer region 15B is arranged at the carcass maximum width position M. In such an aspect, the rigidity in the vicinity of the carcass maximum width position M is appropriately reduced, so that the gap absorption performance is improved.

Although the tire according to the embodiment of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment, and may be carried out in various modes.

Tires having the basic structure shown in FIG. 1 and the carcass ply shown in FIG. 2 were prototyped, and the stability performance during running and the gap absorption performance of each test tire were tested. The common specifications and test methods for each sample tire are as follows.

<Stable performance/gap absorption performance during running>
Each sample tire was mounted on a motorcycle for on-road racing under the following conditions. The test rider ran this motorcycle on an on-road circuit course, and sensoryly evaluated the stability performance and the gap absorption performance during running at this time. The stability performance during traveling is performance related to steering wheel response, lane change stability, traction, grip, and the like. The gap absorption performance is performance related to riding comfort when traveling through a gap due to a step or the like. The result is displayed with a maximum of 10. The larger the value, the better.
Tire size: 120/70R17 (front wheel), 200/55R17 (rear wheel)
Rim size: 3.50 MT (front wheel), 6.00 MT (rear wheel)
Internal pressure: 250kPa (front wheel), 290kPa (rear wheel)
Displacement: 1000cc
Wa/TW: 91%
L1/H: 3%
La: 36 mm
“Comprehensive” in Table 1 is the sum of the results of “stable performance during traveling” and “gap absorption performance”.

As a result of the test, it was confirmed that the tires of the examples had improved gap absorption performance while maintaining stable performance during running.

1 Pneumatic Tire for Motorcycle 4 Bead Section 5 Bead Core 6 Carcass 9 Carcass Ply 8 Carcass Cord 10 Main Body 10A Outside Body Area 11 Winding Part 11e Winding End K Tire Side

Claims (11)

A pneumatic tire for a motorcycle having a carcass,
The carcass includes a carcass ply that is a layer of a carcass cord,
The carcass ply has a main body portion that extends between bead cores that are respectively embedded in a pair of bead portions, and a pair of winding portions that are folded back from the tire axial direction inner side to the outer side around the respective bead cores,
The pair of hoisting portions each have hoisting ends on the tire side,
Regarding the angle of the carcass cord with respect to the tire circumferential direction, each of the pair of hoisting portions is larger than a main body portion outer region located outside the hoisting end of the main body portion in the tire radial direction,
Pneumatic tires for motorcycles. The motorcycle according to claim 1, wherein an inner region of the main body portion, which is located on an inner side in the tire radial direction with respect to the winding end of the main body portion, is larger than an outer region of the main body portion with respect to an angle of the carcass cord with respect to the tire circumferential direction. Pneumatic tires. The motorcycle according to claim 1 or 2, wherein a difference between an angle of the pair of hoisting portions with respect to the tire circumferential direction of the carcass cord and the angle of the carcass cord in the outer region of the main body portion is 5 degrees or more. Pneumatic tires. The pneumatic tire for a motorcycle according to claim 3, wherein the difference is 15 degrees or less. The hoisting end is located radially inward of a tire radial direction outward from a bead base line and is 1.5 times a tire radial direction distance between a carcass maximum width position and the bead baseline. 4. The pneumatic tire for a motorcycle according to any one of 4 above. The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein a belt layer is arranged on the tread portion on the outer side in the tire radial direction of the carcass. The pneumatic tire for a motorcycle according to claim 6, wherein an outer end of the belt layer in the tire axial direction is outside the carcass maximum width position in the tire radial direction. The pneumatic tire for a motorcycle according to claim 6 or 7, wherein a distance in the tire radial direction between the winding end and an outer end of the belt layer in the tire axial direction is 10 to 20 mm. The pneumatic tire for a motorcycle according to any one of claims 1 to 8, wherein an angle of the pair of hoisting portions with respect to a tire circumferential direction of the carcass cord is 70 to 90 degrees. The pneumatic tire for a motorcycle according to any one of claims 1 to 9, wherein an angle of the carcass cord in the outer region of the main body portion with respect to a tire circumferential direction is 65 to 85 degrees. 11. Regarding the angle of the carcass cord with respect to the tire circumferential direction, in the main body portion inner region located on the tire radial direction inner side of the winding end of the main body portion, gradually increases toward the tire radial direction inner side. A pneumatic tire for a motorcycle according to Crab.

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