JPH11291715A - Motorcycle tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heal-and-toe wear while exhibiting excellent wet and dry running performance by forming a slant groove nearly toward an external force. SOLUTION: A motorcycle tire has slant grooves 10 continuously extending from a tire equator C side to a tread edge E1. A half tread surface is divided into three equal areas, that is, an inner area Yi, a middle area Ym, and an outer area Yo. To a reversal rotational circumferential direction line L0, an angle α1 made by a main part 12M of an inner groove part 12 of the slant groove 10 disposed in the inner area Yi is 0 to +35 deg., an angle α2 made by a main part 13M of a middle groove part 13 disposed in the middle area Ym is +30 to +100 deg., and an angle α3 made by a main part 14M of an outer groove part 14 disposed in the outer area Yo is +90 to +130 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use as a tire for a front wheel of a motorcycle, and is capable of suppressing uneven wear in a tread shoulder portion while exhibiting excellent wet running performance and dry running performance. Regarding tires.

[0002]

2. Description of the Related Art With the increase in output and performance of vehicles, there is a strong demand for high-performance tires that can safely run at a high speed even in motorcycle tires. Therefore, tread patterns have been improved. I have.

The role of this tread pattern is to drain the water between the tires and the road surface in wet running to secure a ground contact area with the road surface. As shown, the tire anti-rotation direction R moves from the tire equator C side to the tread edge E1 side.
A tread pattern in which a C-shaped inclined groove a that extends while increasing the inclination angle θ in a range of 0 to 90 degrees is widely used.

[0004] In this pattern, the inclined groove a is sequentially grounded from its inner end a1 when the tire rotates, so that the water in the groove is efficiently discharged from the tire equator side to both outer sides (the tread edge E1 side) along the flowing water line. Because it is well discharged, it has an excellent drainage effect. Further, in the central portion of the tread that contacts the ground when traveling straight or turning with a large radius of curvature, the circumferential groove a has a shallow angle with respect to the tire circumferential direction, so that the circumferential rigidity is high. Moreover, since the inclined groove a is directed toward the tire axial direction in response to the lateral force that increases with the camber angle during turning, the lateral rigidity is increased in the tread shoulder portion that comes into contact with the ground during small turning. As a result, excellent straight running stability and turning performance can be exhibited even in dry running.

[0005]

However, unlike the rear wheel tire, the front wheel tire always receives the rolling resistance P1 in the tire rotation direction F during both driving and braking, and therefore the inclined groove a in the tread shoulder portion. However, there is a problem that the so-called heel-and-toe wear b occurs, and the turning performance is deteriorated early.

In order to suppress the heel & toe wear b, the pattern rigidity at the tread shoulder portion is reduced by, for example, reducing the groove width and groove depth of the inclined groove a, or making the groove wall surface gentle. Although measures such as increasing the drainage capacity are taken, the groove volume is reduced, and the drainage performance is reduced.

Therefore, as a result of repeated studies by the present inventors, the external force P actually acting on the tread shoulder portion is determined by the lateral force P2 during turning and the rolling resistance P in the tire rotation direction F.
By forming the inclined groove a that is as close as possible to the external force P, the rigidity with respect to the external force P is increased, the turning performance in dry running and the heel & toe wear b are suppressed. Was achieved. In addition, it has been found that in this case, the slip of the tread generated in the direction of the external force causes relative movement with the water in the groove, so that the water easily flows in the groove and the drainage property is improved.

That is, the present invention is based on the fact that the inclined groove is formed in a direction close to the external force in the tread shoulder portion, and the heel and toe wear in the tread shoulder portion is exhibited while exhibiting excellent wet running performance and dry running performance. It aims to provide a motorcycle tire that can be suppressed.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a motorcycle tire having a tread surface in a meridional section of the tire having a convex arc shape centered on the tire equator toward a tread edge. A plurality of inclined grooves extending continuously from the tire equator side to the tread edge and circumferentially spaced on both sides of the tire equator, and a half tread surface between the tire equator and the tread edge is formed by the first ,
The main portion of the inner groove portion of the inclined groove located in the inner region divided into three regions from the tire equator into the inner region, the middle region, and the outer region by the second circumferential boundary line forms a circumferential line in the anti-rotation direction. The angle α1 is 0 to +35 degrees, the angle α2 formed by the main portion of the middle groove portion located in the middle region is +30 to +100 degrees, and the angle α3 formed by the main portion of the outer groove portion located in the outer region is +90 to +1.
It is characterized by 30 degrees.

The angle β1 formed by the line segment between the starting point of the inner groove portion on the tire equator side and the first joint point where the inner groove portion continues to the middle groove portion is defined as an angle β1 between 0 and 0 in the anti-rotation direction. +30
The angle β2 formed by the line segment between the first joint point and the second joint point where the middle groove portion continues to the outer groove portion is +20 to +20.
80 degrees, and the angle β3 formed by the line segment between the second joint point and the outer end point of the outer groove portion is set to +80 to +150 degrees, so that the wet running property, the dry running property, and the heel resistance & More preferred for toe wear.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a tire 1 for a motorcycle.
2 shows a meridional section when (hereinafter referred to as tire 1) is a front wheel tire.

In the figure, a tire 1 has a tread portion 2 and
It has sidewall portions 3 extending inward in the tire radial direction from both ends thereof, and bead portions 4 located at radially inner ends of the respective sidewall portions 3 in the tire radial direction. The tire strength and rigidity are increased by the carcass 6 to be bridged and the belt layer 7 disposed radially outside the carcass 6 and inside the tread portion 2.

The carcass 6 is provided on both sides of a ply main body extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3, and a winding portion for winding the bead core 5 from the inside to the outside in the tire axial direction. The space between the ply body and the winding portion is filled with a bead apex rubber 8 extending outward from the bead core 5 in the tire radial direction. The carcass 6 is composed of at least one carcass ply 6A in which carcass cords are radially arranged at an angle of 75 to 90 degrees with respect to the tire circumferential direction. The raised high turn-up structure increases the tire lateral rigidity together with the bead apex rubber 8. As the carcass cord, an organic fiber cord such as nylon, rayon, or polyester is used.

The belt layer 7 is formed of two belt plies 7A and 7B in which the belt cords are arranged at a small angle of 30 degrees or less with respect to the tire circumferential direction, in this example, at an angle of 20 degrees. The belt plies 7A and 7B are arranged in different directions so that the cord has a strong truss structure crossing between the plies. By this, tread part 2
Almost the entire area is reinforced with a tag effect. As the belt cord, an organic fiber cord such as nylon, rayon, polyester, or aromatic polyamide, particularly a high modulus aromatic polyamide fiber cord or the like is suitably used. The belt layer 7 can also be formed by, for example, a spiral cord wound parallel cord ply at an angle of approximately 0 degrees with respect to the tire circumferential direction.

In the tread portion 2, in the tire meridional section, the tread surface 2S is curved in a convex arc around the tire equator C, and the distance between the tread edges E1, E1 in the tire axial direction is equal to the tire tread length. It is formed to have the maximum width.

As shown in FIG. 2, the tread portion 2 has an inclined groove 10 extending continuously from the tire equator C toward the tread edge E1 and circumferentially spaced on both sides of the tire equator C. A provided tread groove is formed. In this example, the case where the tread groove extends substantially linearly on the tire equator C and has a vertical groove 11 that is not in contact with the inclined groove 10 is illustrated.

In the present embodiment, the inclined groove 10 is formed by a main inclined groove 10A and a sub-inclined groove 10B. The main inclined groove 10A is provided with a starting point in the inner area Yi when the half tread surface 2S1 between the tire equator C and the tread edge E1 is equally divided into an inner area Yi, a middle area Ym, and an outer area Yo. It is defined as a groove having K1 and extending to the three regions Yi, Ym, Yo, and the inclined groove 10 needs to include at least the main inclined groove 10A. In this example, the sub-inclined groove 10B has a start point K1 in the middle area Ym and extends to the two areas Ym and Yo.

Here, the inner area Yi, the middle area Ym, and the outer area Yo are, specifically, one-third of the half width TW of the tread along the tread surface 2S between the tire equator C and the tread edge E1.
A first circumferential boundary line L1 separated from the tire equator C along the tread surface 2S, and a second circumferential boundary separated from the tire equator C along the tread surface 2S by a distance of 2/3. This is a region obtained by dividing the half tread surface 2S1 into three by the line L2. The inner region Yi is a width region that mainly touches the ground when traveling straight ahead, the middle region Ym is a width region that mainly touches the ground when turning around a corner having a relatively large radius of curvature, and the outer region Yo. Means an area that touches the ground when turning around a corner having a small radius of curvature at a large bank angle. Conventionally, heel and toe wear has occurred in a tread shoulder portion substantially corresponding to the outer region Yo.

Next, as shown in the enlarged view of FIG. 3, in the tire 1, the main portion 12M of the inner groove portion 12 located in the inner region Yi of the inclined groove 10 has a circumferential line L in the anti-rotation direction.
0 (meaning a circumferential line extending in the anti-rotation direction R of the tire) is 0 to +35 degrees, and the angle α2 formed by the main portion 13M of the middle groove portion 13 located in the middle region Ym is +3.
The angle α3 formed by the main portion 14M of the outer groove portion 14 located in the outer region Yo is restricted to +90 to +130 degrees, and each angle is set to α3>α2> α1.

That is, in the inner region Yi, the main portion 12M of the inner groove portion 12 has a C-shape inclined in the anti-rotation direction R from the tire equator C side toward the tread edge E1 side. Therefore, when the tire is rotating, the ground is sequentially grounded from the starting end point K1, and the water in the groove can be efficiently drained from the equator side of the tire to both outsides along the flowing water line, and excellent wet running when traveling straight at a high speed is required. The character is exhibited. Further, since the angle α1 is a shallow angle, the rigidity in the circumferential direction is high, and the straight running stability in dry running is maintained at a high level.

Conversely, in the outer region Yo, the outer groove portion 14
Of the tread edge E1 from the tire equator C side
In the rotation direction F toward the side. This inclination direction is
The direction of the resultant force (external force P) of the lateral force P2 acting on the outer region Yo and the rolling resistance P1 is approximated.
As a result, the stiffness of the tire is increased and the amount of deformation is reduced, so that turning performance in dry running and suppression of heel & toe wear are achieved. In addition, slip of the tread generated in the direction of the external force causes relative movement with the water in the groove, so that the water easily flows in the groove and drainage is improved.

In the main portion 12M of the inner groove portion 12, the direction of the external force acting on the inner region Yi is not intentionally approximated, but in this inner region Yi, the angle α1 is 0 to 0 as described above. Since the angle is as small as 35 degrees, the circumferential rigidity is sufficiently ensured. Also, if the inner groove portion 12 is approximated to an external force in the same manner as the outer groove portion 14, the effect of improving the rigidity is hardly expected, but water in the groove is concentrated from both outer sides toward the tire equator C. This is because adverse effects such as impairment of wet running performance are adversely affected.

In the middle region Ym, the main portion 13M of the middle groove portion 13 extends at an intermediate angle α2 between the inner groove portion 12 and the outer groove portion 14, so that both directions from straight traveling to turning at a deep bank angle are possible. The transition can be made smoothly without obstructing the advantages, and high running performance can be exhibited as a whole.

Here, the main parts 12M, 13M, 14
M means a portion of each of the groove portions 12, 13, 14 that is at least 70% of the groove length along the respective groove center line. Further, each groove portion 12, 13, 14 can be formed into various shapes, for example, a curved shape formed by connecting arcs, a bent line formed by connecting straight lines, and a combination thereof.
An example is shown in which a curved line is formed by connecting substantially straight lines. In the case of a curve, the angles α1, α2, α3 are defined as angles formed by tangents.

If the angle α1 exceeds +35 degrees, the rigidity in the circumferential direction becomes insufficient, so that the straight running stability in dry running is impaired and the wet running performance (drainability) is reduced. When the angle α2 is smaller than +30 degrees and larger than +100 degrees, one of the circumferential stiffness and the lateral stiffness becomes too small to reduce the straight running stability or turning performance in dry running, and furthermore, a deep bank angle from straight running. Smooth transition to a turn at the cruiser impairs maneuverability. Further, when the angle α3 is smaller than +90 degrees and larger than +130 degrees, the heel and toe wear cannot be suppressed and the turning performance is reduced.
When it is larger than 30 degrees, the wet running property (drainage property) also decreases.

As shown in FIG. 4, for the wet running property, the dry running property, and the heel & toe wear resistance, the starting point K1 of the inner groove portion 12 on the tire equator side,
First joint point K2 where inner groove portion 12 is continuous with middle groove portion 13
Angle β1 between the line segment and the circumferential line L0 in the anti-rotation direction.
0 to +30 degrees, the first joint point K2 and the middle groove portion 1
The angle β2 formed by the line segment between the second joint point 3 and the second joint point K3 connected to the outer groove portion 14 is +20 to +80 degrees, and the angle between the second joint point K3 and the outer end point K4 of the outer groove portion 14 is It is preferable that the angle β3 formed by the line segments between +80 and +150 degrees.

In this example, the inclined groove 10 on one side and the inclined groove 10 on the other side of the tire equator C are, as shown in FIG.
The inclined pitch 10 is uniformly distributed over the entire tread area by alternately arranging the main inclined grooves 10A and the sub-inclined grooves 10B in a staggered arrangement in which the circumferential pitch T is shifted by about 1/2. .

In addition to the inclined groove 10, the main inclined groove 1
The starting point K1 of 0A may be located on the tire equator C or in the other inner region Yi beyond the tire equator C and may be extended. In this case, the extended portion provides drainage near the tire equator C. In addition, the vertical groove 11 can be deleted.

In the present application, the groove width, groove depth, groove cross-sectional shape and the like of the inclined groove 10 are not particularly limited, but those of a conventional tire can be appropriately adopted.

Alternatively, the tire 1 may adopt a bias structure in which the carcass 6 is formed from two or more, for example, two carcass plies in which the carcass cords are arranged at an angle of 30 to 60 degrees. In the case of such a bias structure, instead of the belt layer 7, a breaker layer comprising two or more, for example, two plies, in which the breaker cords of the organic fibers are arranged at an angle of about 30 to 60 degrees substantially the same as the carcass ply Is provided.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The tire having the structure shown in FIG.
0 / 70-17 tires were prototyped based on the specifications in Table 1, and the wet running performance (drainage) of each test tire was measured.
Dry running performance and heel & toe wear resistance were tested, and the results are shown in Table 1. All the tires have the same specifications and structures other than Table 1.

[0032] The dry running performance was measured by using the rim (M
T3.00 × 17), mounted on the front wheel of a motorcycle (400 cc) under the conditions of internal pressure (220 kpa), run on a dry circuit course at an almost limit speed, and drive straight ahead and turn according to the sensory evaluation by the driver. Comprehensive evaluation of maneuverability, etc., 3 (good), (good), (bad)
It was judged at the stage. -Heel resistance and toe abrasion resistance are measured by one round using the vehicle.
Measure the maximum value of heel & toe wear after 150 laps on a 2 km dry circuit course, and select ○ (excellent), △ (acceptable), ×
(No) was determined in three stages. The wet running performance (drainage performance) was evaluated as follows: the vehicle was used to drive a 200 mm round track course sprinkled on the road surface, and the steering stability at that time was evaluated by a sensory evaluation by a driver. Judgment was made in three stages of Δ (acceptable) and × (impossible).

[0033]

[Table 1]

As shown in Table 1, in the tire of the embodiment, since the angles α1, α2, and α3 are regulated within a predetermined range, the wet running property (drainability), the dry running property, and the heel & toe resistance. It can be confirmed that the abrasion can be improved.

[0035]

The motorcycle tire of the present invention is constructed as described above, and the inclined groove is formed in a direction close to the external force, so that the heel and toe while exhibiting excellent wet running performance and dry running performance can be obtained. Wear can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a motorcycle tire according to one embodiment of the present invention.

FIG. 2 is a developed view showing the tread pattern.

FIG. 3 is an enlarged view illustrating an inclined groove.

FIG. 4 is an enlarged view for explaining an angle β of the inclined groove.

FIG. 5 is a development view showing an example of a tread pattern of a conventional tire.

[Explanation of symbols]

 2S Tread surface 2S1 Half tread surface 10, 10A, 10B Inclined groove 12 Main part of inner groove part 12M Main part of inner groove part 13 Main part of middle groove part 13M Main part of middle groove part 14 Main part of outer groove part 14M Outer groove Main part of part 10, 10A, 10B Inclined groove C Tire equator E1 Tread edge K1 Start point K2 First joint point K3 Second joint point K4 Outer end point L0 Anti-rotational circumferential line L1, L2 First, second Circumferential boundary line Yc inner area Ym middle area Yo outer area

Claims (2)

[Claims] 1. A tire for a motorcycle, wherein a tread surface in a meridional section of the tire has a convex arc shape centered on the tire equator toward the tread edge, and continuously extends from the tire equator side to the tread edge. A plurality of inclined grooves are provided circumferentially spaced on both sides of the equator, and a semi-tread surface between the tire equator and the tread edge is defined by a first and a second circumferential boundary line from the tire equator side to an inner region, An angle α1 that a main part of the inner groove portion of the inclined groove located in the inner region divided into the middle region and the outer region is 0 to +35 degrees, and an inner groove portion located in the middle region Is +30 to +100 degrees, and the angle α3 formed by the main portion of the outer groove portion located in the outer region is +90.
A tire for a motorcycle, wherein the angle is set to +130 degrees. 2. A starting point on the tire equator side of the inner groove portion,
An angle β1 between a line segment between the inner groove portion and the first joint point connected to the middle groove portion and a circumferential line in the anti-rotation direction is 0 to +30 degrees,
The first joint point and a second joint part where the middle groove part is continuous with the outer groove part.
Angle β2 formed by the line segment between the joints of
2. The motorcycle tire according to claim 1, wherein an angle β3 formed by a line segment between the second joint point and an outer end point of the outer groove portion is +80 to +150 degrees. 3.