JP2009051363A - Pneumatic tire for two-wheeled vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a two-wheeled vehicle suppressed in the degradation of various kinds of tire performance by proving a spiral belt member. <P>SOLUTION: The spiral belt layer 20 of the pneumatic tire 10 for the two-wheeled vehicle includes a center spiral belt member 20C extending over a tire center CL, and a pair of shoulder spiral belt members 20L, 20R arranged on tread shoulders at both sides in a tire width direction, respectively, where L represents a tread surface distance from the tire center CL to a tread end T. Adjacent ends of the center spiral belt member 20C and the shoulder spiral belt members 20L, 20R are separated from each other at an interval D within a range of 0.1L-0.42L along a tread surface. A distance W2 along the tread surface from the tire center CL to the end 20CE of the center spiral belt member 20C is set within in a range of 0.08-0.25 L. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for two-wheeled vehicles, and more particularly, particularly at the time of high-speed steering stability, traction performance during deep cornering that greatly defeats a motorcycle, wear resistance performance of a tire shoulder, and straight traveling The present invention relates to a pneumatic tire for a motorcycle having improved ride comfort performance.

  In a high-performance pneumatic tire for a motorcycle, since the rotational speed of the tire becomes high, the influence of centrifugal force is large, and the tread portion of the tire may expand outward in the tire radial direction, which may impair the steering stability performance. In order to prevent this, a tire structure has been developed in which an organic fiber or steel reinforcing member (spiral member) is wound around the tread portion of the tire so that it is substantially parallel to the tire equatorial plane (tire center). ing. Nylon fibers (“Nylon” is a registered trademark of DuPont), aromatic polyamide (Kevlar), steel, and the like are used as a reinforcing member wound in a spiral shape along the tire equatorial plane. Among them, aromatic polyamide (Kevlar) and steel are attracting attention because they can suppress expansion of the tread portion without stretching even at high temperatures.

When these members are attached to the crown of the tire, the so-called “tangle” effect (the tire is pressed by the centrifugal force even when the tire is pressed at a high speed by pressing the crown of the tire like a gutter in a bathtub). Since it is possible to improve the effect of exhibiting high steering stability performance and durability without swelling, many proposals have been made to arrange the spiral cord in the crown portion of the tire (see, for example, Patent Documents 1 to 5).
It is known that a pneumatic tire for a motorcycle around which these spiral members are wound has excellent steering stability performance at high speed and very high traction performance.

However, the steering stability performance (especially turning performance) when a vehicle (for example, a motorcycle) equipped with a pneumatic tire for a motorcycle is greatly defeated is greatly improved by winding a reinforcing member (spiral member). Do not mean. Riders may be asked to improve the grip when the bike is knocked down.
In addition, it is often pointed out that the arrangement of the spiral member makes the tire skeleton member stiff and deteriorates the ride comfort performance when going straight.
JP 2004-067059 A JP 2004-067058 A JP 2003-011614 A JP 2002-316512 A JP 09-226319 A

  In view of the above-described facts, an object of the present invention is to provide a pneumatic tire for a motorcycle that suppresses deterioration in various tire performances due to the provision of a spiral belt member.

The present inventor conducted the following investigations in completing the present invention.
In a pneumatic tire for a two-wheeled vehicle, since the two-wheeled vehicle turns while tilting the vehicle body, the place where the tread portion is in contact with the ground is different between when going straight and when turning. In other words, the center portion of the tread portion is used when going straight, and the end portion of the tread portion is used when turning. Therefore, the shape of the tire is very round compared to the tire for passenger cars. Due to this round crown shape (the shape of the tread portion of the tire), the following unique characteristics can be seen especially during turning.

  In a pneumatic tire for a motorcycle, particularly with respect to turning performance when the vehicle body is largely tilted, an end portion on one side of the tread of the tire is grounded to generate a grip force. When the vehicle is turned by largely tilting the vehicle body, a grounding state as shown in FIG. 6 is obtained. The width of the grounding range is about 25% of the entire tread width. Considering the ground contact shape at this time, as shown in FIG. 6, the deformation state of the tread portion is different between the ground shape near the center and the ground shape near the tread end. Looking at the deformation of the tread portion 108 in the tire rotation direction (also referred to as the tire circumferential direction or tire front-rear direction), the tread portion 108C near the center is in the driving state, and the tread portion 108E near the tread end portion is braked. It is a running state.

Here, driving means that when the tire is cut along the equator direction, the deformation of the tread portion is sheared backward in the tire traveling direction on the lower surface of the tread (the surface in contact with the skeleton member inside the tire). This is a shearing state in which the tread surface that receives a force and is in contact with the road surface is deformed forward in the tire traveling direction, and is a deformation that occurs when a driving force is applied to the tire. On the other hand, braking is the reverse of driving. In braking, the tread deformation is caused by the force that shears the inside of the tire (belt) forward, and the tread surface that contacts the road surface is deformed backward. It is in a sheared state and becomes the movement of the tire when braking. As shown in FIG. 6, when turning at a large angle such as a camber angle of 45 degrees, a driving state appears in the ground contact area near the tread center even when the tire is rotated without driving force or braking force. A braking state appears near the end of the tread. This is due to the difference in the radius of the belt portion of the tire (diameter difference). In a pneumatic tire for a motorcycle, since the crown portion of the tire is greatly rounded, the distance from the rotation shaft to the belt is greatly different between the tread center portion and the tread end portion. In the case of FIG. 6, the radius RC at the position near the center of the ground contact portion is clearly larger than the radius RA at the position near the tread end of the ground contact portion. Since the angular speed at which the tire rotates is the same, the speed of the belt part (when the tire is in contact with the road surface, it means the speed in the tire circumferential direction along the road surface; the belt radius multiplied by the tire angular speed) is The RA part with a larger radius is faster. The tread surface of the tire does not receive a shearing force in the front-rear direction at the moment of contact with the road surface, but proceeds with tire rotation while in contact with the road surface, and undergoes a shear deformation in the front-rear direction when leaving the road surface. . At this time, in the tread portion 108C near the tire center where the belt speed is fast, shear deformation in the driving state occurs, and on the tire tread end side (tread portion 108E near the tread end portion), the belt speed is slow, so the brake is applied. Deformation has occurred. This is a modification of the tread portion 108 in the front-rear direction.
Due to such extra deformation during turning, uneven wear tends to occur at the tire shoulder. In particular, in region A (see FIG. 6), which is a region of less than 10% from the tread edge, braking deformation is large, so that slippage in the tire circumferential direction is easily caused at the kicked-out portion, and wear is likely to occur.

  In addition, since the tread undergoes reverse shear deformation in the forward and backward directions, it includes wasteful behavior and wasteful tire grip force during turning. The region A shown in FIG. 6 has already undergone shear deformation in the tire circumferential direction, and even if a lateral force is applied and the tread is deformed laterally, the friction coefficient is already used in the tire circumferential direction. Inefficiency without using 100% friction coefficient. Ideally, if the deformation of the tread portion that is in contact with the ground does not occur in the circumferential direction but occurs entirely in the lateral direction, the lateral force is maximized. Further, if there is a variation in the deformation of the tread in the circumferential direction, a variation in the way of sliding also occurs. For example, when accelerating by applying driving force to the tire while the tire is tilted, the driving grip force is exerted as soon as the driving force is applied to the tire in the tread portion 108C near the center already in the driving state. In the tread portion 108E near the tread end in the braking state, the braking deformation once returns to neutral, and then shifts to the deformation on the driving side, so it is difficult to contribute to the driving force. A large traction force is required to bring the tread portion 108E near the tread end into the driving state, and when the accelerator is opened and the driving force is applied to the tire to apply such a traction force, the driving state is originally in the driving state. The tread on the tire center side tends to slip and fall into an idle state.

  With respect to such a problem, it is considered that if the tread deformation of the tire shoulder portion on the braking side is originally set on the driving side as much as possible, the traction force can be exerted greatly at the tread end portion. For this purpose, one solution is to increase the speed of the belt at the end of the tread. However, as described above, the speed of the belt is determined by the belt radius, and the belt radius is too large. And cannot be used as a pneumatic tire for motorcycles.

  Therefore, it is conceivable to increase the belt speed by making the belt easily extend in the tire circumferential direction at the tread end portion after contact with the ground. That is, when turning with a large camber angle (hereinafter referred to as a large camber), the center side half of the ground contact portion is structured so that the belt does not extend in the tire circumferential direction (equator direction), and the tread end side half is If the belt can be extended in the tire circumferential direction, the belt on the tread end side extends after contact with the ground, so that the belt speed on the tread end side increases and the braking deformation on the tread end side can be reduced. As a result, the traction performance during large camber (acceleration performance from turning with a large tilt of the motorcycle) is improved.

  In the prior art, it is common to wrap the spiral belt layer around the entire area of the tread. With such a tire, the belt of the shoulder portion of the tread cannot be extended in the equator direction. Therefore, if the spiral belt is not wound around the tread end portion and is arranged only on the center side, the belt speed at the tread end portion increases during large camber, and the traction performance can be improved. Further, when the belt speed of the tread shoulder portion increases during a large camber, the speed of the belt on the tread center side approaches the speed of the tread center side, thereby suppressing an extra movement of the tread portion that is in contact with the ground. That is, the tread that receives the shearing force in the reverse direction so far receives the shearing force in the same direction, so that useless movement is eliminated and the occurrence of uneven wear can be suppressed. In addition, since the spiral belt layer is arranged in the tread center part, tires when driving at high speed (when the vehicle (motorcycle etc.) wearing a pneumatic tire for motorcycles is upright because the speed is high) As a result, the steering stability performance at a high speed is maintained at the same level as that of a tire having a full width spiral belt layer.

  On the other hand, the deformation behavior during straight running was confirmed. FIG. 6 shows a cross-sectional shape of a tire when the motorcycle stands upright at CA0 and goes straight. The grounding range varies when the load varies during acceleration or braking, but is approximately 25% of the tread width. At this time, the tread portion is bent in the vicinity of the ground contact end portion of the ground contact width. If the tread is easily bent in this region, the riding comfort performance is improved. When there is a spiral belt near the ground contact edge, the spiral belt is sufficiently stiff, and further restrains the movement of the crossing belt used in conjunction with the spiral belt. Comfort performance may deteriorate.

The present inventor conducted the above-described studies and repeated further experiments to complete the present invention.
According to the first aspect of the present invention, a belt layer and a tread portion are sequentially provided on the outer side in the tire radial direction of the crown portion of the carcass layer formed of one or more carcass plies, and the belt layer is a single wire or arranged in parallel. A spiral belt layer in which a belt-shaped rubber-coated cord layer formed by embedding a plurality of cords in a coated rubber is spirally wound so as to form a cord angle within a range of 0 to 5 degrees with respect to the tire circumferential direction. In a pneumatic tire for a motorcycle having at least one tire, the distance from the tire center to the position of 0.65 L to 0.85 L along the tread surface when the tread surface distance from the tire center to the tread edge is L The spiral belt layer is present only on the center side spiral belt member straddling the tire center and the tire width. A pair of shoulder-side spiral belt members disposed on the tread shoulder sides on both sides in the opposite direction, and adjacent ends of the center-side spiral belt member and the shoulder-side spiral belt member are along the tread surface. The distance from the tire center to the end of the center side spiral belt member is within the range of 0.08L to 0.25L. The distance along the tread surface from the tire center to the end on the tire center side of the shoulder side spiral belt member is in the range of 0.25L to 0.5L.

The reason why the cord angle of the spiral belt layer is set within the range of 0 to 5 degrees with respect to the tire circumferential direction is that a manufacturing error is taken into consideration.
The invention according to claim 1 stipulates that the spiral belt layer is divided into three parts, one at the tire center portion, and a pair at both sides of the tread. The center side spiral belt member has a role to prevent the tire center portion from expanding when the tire rotates at a high speed while going straight, and if the tire center portion does not expand, the contact pressure of the tread center portion does not increase due to high speed rolling. In addition, it is possible to prevent the rubber at the tread center portion from malfunctioning. In addition, since it exhibits a tagging effect at the tire center during high-speed rolling, steering stability performance during high-speed rolling can be ensured.

  In the first aspect of the invention, the width in the peripheral direction of the center side spiral belt member is defined. Here, the peripheral direction width is a width in a substantially arc direction along the outer periphery. As described above, the ground contact portion when the vehicle is traveling straight ahead is an area of 25% of the tire center portion. That is, if the total width of the tread is 2L, the center portion is grounded for a width of 0.5L. If the width of the spiral belt member (center side spiral belt member) wound around the center portion is 0.08 L on one side from the tire center (center line), the width is 0.16 L on both sides, which is the ground contact width of 0.5 L 1/3. Thus, by winding the center side spiral belt member around at least 1/3 of the ground contact portion, the tire can be prevented from expanding. The lower limit of 0.08L is a minimum width for preventing the center side spiral belt member from expanding the centrifugal force of the tire center portion when traveling straight. If the width of the center side spiral belt member is smaller than 0.08L, the effect of preventing the tire from expanding the centrifugal force is reduced. The upper limit of 0.25L is the same as the width of the ground contact portion when traveling straight. Since the width is 0.25L from the tire center, the width is 0.5L on both sides, which is the ground contact width. If the width exceeds 0.5L, the spiral belt member will be present even at the most severely deformed ground contact end SE (see FIG. 6), and the belt skeleton of the tread portion will be difficult to bend, and the riding comfort performance will deteriorate. .

  Furthermore, in the invention according to claim 1, the end position on the tire center side of the pair of shoulder side spiral belt members arranged in the tread shoulder portion is set within the range of 0.25L to 0.5L from the tire center. When the shoulder side spiral belt member starts to be wound from a position smaller than 0.25L from the tire center, the spiral belt member also exists in the portion of the tire cross section when straight traveling in FIG. The ride comfort performance of the car deteriorates. In the case of a commercially available motorcycle, when it is used in a general manner, it takes a long time to go straight ahead, and the ride comfort performance when going straight ahead is important. If the spiral belt starts to be wound from a position wider than 0.5 L from the tire center, the width of the spiral belt at the tread shoulder portion becomes too narrow. That is, in FIG. 6, the ground contact width when turning at CA 50 degrees is in a range of 0.5 L from the tread edge. In particular, in FIG. 6, unless a spiral belt member is wound around the region C, not only the CA 50 degree belt in-plane shear rigidity is insufficient, but also the belt in the region C is easily stretched in the circumferential direction. The effect cannot be demonstrated. That is, in order to wind the spiral belt member around the region turning at 50 degrees CA, the spiral belt must be wound from a position of 0.5 L or less from the tire center.

  The center side spiral belt member and the shoulder side spiral belt member may be configured differently. For example, if the center-side spiral belt member is made of an organic fiber such as aromatic polyamide, the ride comfort performance during straight travel is further improved. Further, if the shoulder side spiral belt member is made of steel, the in-plane shear rigidity can be increased, and the turning performance at the time of large CA such as CA 50 degrees can be further enhanced.

  In the invention according to claim 1, between the center side spiral belt member straddling the tire center portion and a pair of shoulder side spiral belt members disposed on the tread shoulder side on both sides in the tire width direction (adjacent end portions) The distance between them is in the range of 0.1L to 0.42L. Thereby, the flexibility of the skeleton member is given, and it is easy to bend when the tire goes straight. That is, in FIG. 7, by providing this gap in the region near the ground contact edge SE where the deformation of the tread is most severe, the tire is easily bent and the riding comfort performance is improved. In order to make this effect remarkable, it is preferable to secure this gap (interval) of at least 10 mm.

  In the invention described in claim 1, the width of the spiral belt layer, that is, the position of the end portion of the pair of left and right shoulder side spiral belt members that is farthest from the tread center is defined. The width of the tread surface of the tread half is L, that is, the distance from the tire center to the tread edge along the tire surface is L. At this time, the width of the spiral belt layer is defined as a range from the tire center to a position of 0.65L to 0.85L. That is, at any tread end side, the spiral belt layer does not exist in the range of the width 0.35L to 0.15L from the tread end.

  The grounds for setting the width of the spiral belt layer to 0.65 L to 0.85 L are based on considering a ground contact portion in the vicinity of a camber angle of 50 degrees, which is the time when the motorcycle falls most greatly. At the time of turning with a camber angle of 50 degrees, only the width portion of 0.4 to 0.5 L of the total tread width 2 L is grounded. In the first aspect of the present invention, as described above, the spiral belt layer is formed in the tread center portion to prevent the skeletal member from extending in the circumferential direction in the ground contact range at the time of large camber, and conversely on the tread end portion side. A structure in which the skeleton member can be positively extended in the tire circumferential direction without forming a spiral belt layer. Half of the grounding portion is a position away from the tread end by 0.2 to 0.25 L, and the end portion of the spiral belt layer is preferably disposed in the vicinity thereof. However, the effect is recognized if the spiral belt is not wound around the tread shoulder side of the grounded portion instead of being halved exactly. Therefore, the range is from 0.65L to 0.85L.

If the width of the spiral belt layer is less than 0.65 L, the spiral belt layer extends on the tire center side of the ground contact surface at the time of large camber, and the belt speed on the center side increases to make it difficult to obtain the effect. If the width of the spiral belt layer exceeds 0.85L, the belt becomes difficult to stretch on the shoulder side (tread end side) of the ground contact surface during large camber, and the belt speed on the shoulder side cannot be increased, resulting in an effect. It's hard to be done
The width of the spiral belt layer is preferably within a range of 0.7L to 0.8L, and more preferably within a range of 0.75L to 0.8L.

  Further, the carcass ply (body ply) has one or more layers. In the case of a single layer, it is almost arranged in a direction that forms 90 degrees with respect to the tire circumferential direction, that is, in a radial direction. In the case of two layers, two sheets may be stacked in the radial direction, or may be arranged so as to cross each other at an angle of 70 degrees with respect to the tire circumferential direction. The carcass bead can be locked by winding it around a bead core and turning it back, cutting the carcass at the bead tip, and placing bead wires on both sides of the cord end. The carcass may be sandwiched between the bead wires.

  In a tire having a spiral belt layer, it is better to arrange a crossing layer in the tread portion in addition to the spiral belt layer. This is because the in-plane shear rigidity of the belt can be increased by combining the crossing layer and the spiral belt layer. When the carcass ply (body ply) is a single layer, the carcass ply is arranged radially (90 degrees on the equator) and does not constitute a crossing layer. Therefore, two or more belt layers can be provided in addition to the spiral belt layer. good. In the case where two carcass plies are arranged, if the two carcass plies are interlaced to function as an intersecting layer, the in-plane shear rigidity of the belt can be kept high without arranging the bell collar layer. Of course, two carcass plies may be crossed and a belt crossing layer may be provided. Further, the carcass ply functions as a crossing layer, and when combined with the spiral belt, the in-plane shear rigidity of the belt can be increased, and the steering stability performance is improved.

  The material of the spiral belt member may be an organic fiber such as aromatic polyamide (trade name is Kevlar, for example), or may be a steel cord. In order to manufacture a spiral belt member, for example, a belt-like body in which one or two or more parallel cords are embedded in a covering rubber is wound around the tire rotation axis in a threaded manner substantially along the tire equator direction. Manufactured.

  According to a second aspect of the present invention, in addition to the spiral bell collar layer, an intersecting belt layer composed of at least two intersecting belt members composed of organic fibers intersecting each other is disposed, and the tire circumferential direction of the intersecting belt The cord angle with respect to is in the range of 30 to 80 degrees.

  The invention according to claim 2 stipulates that there are two crossing bell rod members. By combining the two intersecting belt members with the spiral belt member, the in-plane shear rigidity of the belt can be increased. The cord angle with respect to the tire circumferential direction is 30 to 80 degrees. When the angle is greater than 80 degrees, the angle at which the two belts intersect with each other is small, and the improvement of the in-plane shear rigidity cannot be expected, and the steering stability performance deteriorates. If it is less than 30 degrees, this is the direction approaching the spiral belt layer, and the belt has a characteristic that it is difficult to extend in the tire circumferential direction (tire equator direction). In this case, contrary to the gist of the present invention that the belt of the shoulder portion extends in the tire equator direction in the ground contact region, the skeleton member becomes difficult to extend in the tire equator direction at the tread shoulder portion, and the belt speed of the tread shoulder portion becomes difficult to increase. . Therefore, the tread shoulder portion remains in a braking deformation, and it is difficult to obtain a traction grip, and uneven wear is likely to occur. Furthermore, if it is less than 30 degrees, the crossing angle with the spiral belt member becomes small. For this reason, in addition to a small improvement in the in-plane shear rigidity when combined with the spiral belt member, since the cords close to the tire equator direction overlap three layers, the circumferential out-of-plane bending rigidity with the width direction as the fold is increased. It becomes too high, and the skeleton member of the tread portion is difficult to bend, and the tire becomes lumpy, that is, the riding comfort performance is deteriorated.

  The angle is preferably 45 degrees or more because the skeletal member easily extends in the equator direction. In order to exhibit in-plane shear rigidity, 70 degrees or less is preferable. Here, the angle means an angle measured at the center of the tire.

  The carcass ply when two crossing belt members are present may be radial, or two may be crossed to have an angle. In the case of radial, one carcass ply may be arranged at 90 degrees with respect to the equator direction, or two 90-degree carcass plies may be arranged in an overlapping manner.

  It is preferable that the two crossing bell ridge members are wide with respect to the entire width of the tread. Specifically, when the width is 90% or more and 105% or less of the total width of the tread, the cross belt layer exists at the end of the tread where the spiral belt layer does not exist, and sufficient in-plane shear rigidity is obtained even when turning at a CA of 50 degrees. Can be secured, and the steering stability performance is increased, that is, the lateral force is increased. Here, the full width of the tread is the width in the peripheral direction of the tread portion. The peripheral width of the tread portion is a width in a substantially arc direction along the outer periphery of the tread portion, and is a width of a region that is grounded at every camber angle (CA) during traveling.

  The material of the cross belt member is preferably an organic fiber cord. This is because if a cord having rigidity in the compression direction of the cord, such as a steel cord, is arranged as a crossing layer, the skeletal member has a characteristic that it is difficult to bend out of the plane, the ground contact area is reduced, and the grip force is reduced. If it is an organic fiber cord, it does not have great rigidity in the compression in the cord direction, it can reduce the out-of-plane rigidity of the skeleton member and increase the ground contact area, and it is very strong in the cord pulling direction This is because the in-plane rigidity can be effectively increased due to the rigidity. The spiral belt may be steel or organic fiber. This is because the spiral belts are not interlaced, and there is no fear of increasing the out-of-plane bending rigidity of the belt more than necessary. When crossing like a crossing belt, it is better to avoid using steel. The material of the cross belt is preferably a fiber having high tensile rigidity such as aromatic polyamide (trade name is, for example, Kevlar) and strong against heat.

  The invention according to claim 3 is characterized in that all of the belt members constituting the spiral belt layer are arranged on the inner side in the tire radial direction than the crossing belt layer.

  According to the third aspect of the present invention, in the case where two crossed bell-belt layers are present, it is defined that the belt member constituting the spiral belt layer is disposed radially inward from the two crossed belt layers. When the spiral belt member is divided and disposed, the belt rigidity of the tire is different between a place where the spiral belt member exists and a place where the spiral belt member does not exist. Due to the characteristic that a motorcycle turns by turning down the vehicle body, the ground contact part of the tire moves in the tread portion in the process of turning down the vehicle body. When the ground contact portion crosses the boundary between the portion where the spiral belt member is present and the portion where the spiral belt member is not present, the rider may feel uncomfortable due to the difference in belt rigidity. According to a fourth aspect of the present invention, the cross belt layer is disposed outside the spiral belt layer in the radial direction, so that the spiral belt layer is divided and the portion where the spiral belt member does not exist is wrapped with the cross bell-belt layer. Yes, you can blur the steps. Therefore, the rider can smoothly fall the vehicle body and smoothly raise the vehicle body during acceleration.

  According to a fourth aspect of the present invention, there is provided a belt reinforcing layer including an organic fiber cord having a cord angle with respect to a tire circumferential direction in a range of 85 to 90 degrees, and the spiral belt layer having a width of 90% or more of a total tread width 2L. And the tread portion.

  According to the fourth aspect of the present invention, the organic fiber member having an angle of 90 degrees with respect to the tire equator direction is disposed outside the spiral belt in the radial direction. This is because, in the tread portion, there are a portion where the spiral belt is present and a portion where the spiral belt is not present, so that the rigidity of the skeleton member of the tire changes abruptly at the boundary between the two, and when the grounding end rides over this portion (that is, This is to prevent the rider from feeling a sense of incongruity due to the tire step when the grounding part moves and crosses this boundary when turning the tire more and more. Compared to the tread rubber, the cords such as the inner belt are very rigid. Therefore, when there is a discontinuous portion in the internal skeleton member, the rider feels the step. Therefore, as described in claim 4, it is difficult to feel this level difference by continuing the tire radial direction outer side belt (often the outermost layer belt) from the tire center to the tire shoulder. is doing. The reason why the angle is set to 90 degrees with respect to the tire equator direction is that the steps can be most effectively prevented by arranging the cords along the width direction. In the fourth aspect of the invention, the angle is given a width of 85 degrees to 90 degrees because it includes manufacturing errors. The width was 90% or more of the total tread width 2L. The purpose of arranging the belt reinforcing layer is to prevent the step from being felt, that is, to end the spiral belt layer with the belt reinforcing layer so that the outermost belt is not divided. Therefore, it is preferable to increase the width and cover the entire area of the tread. If it is 90% or more, the level | step difference of a spiral belt can fully be covered. In addition, although an upper limit is not prescribed | regulated in Claim 4, it may reach a sidewall part exceeding a tread width. In other words, it may be 110%. Preferably, the upper limit is 110% that does not reach the maximum width of the sidewall portion of the tire.

  Further, in claim 3, the crossed belt layer covers the divided spiral belt member, and this crossed belt layer is further provided with another 90-degree belt such as a belt reinforcing layer (the cord angle with respect to the tire circumferential direction is 90 °). If the belt of the degree is placed, it is meaningful because it is more difficult to feel the level difference. According to a fourth aspect of the present invention, the belt reinforcing layer is disposed as a 90 degree belt. The effect is high when the divided spiral belt member exists outside the crossing belt layer in the tire radial direction. In such a case, if the divided spiral belt is covered with the belt reinforcing layer, the step is effectively removed. Can make you feel uncomfortable.

  The 90-degree belt (belt reinforcement layer) is strong in the width direction of the tire and has a characteristic of easily extending in the circumferential direction of the tire. Therefore, if a 90-degree belt (belt reinforcement layer) is disposed so as to reach the tread edge of the tire, the lateral rigidity of the tire shoulder can be increased.

  According to a fourth aspect of the present invention, the cord material of the belt reinforcing layer arranged as a 90 degree belt is an organic fiber. This is because a pneumatic tire for a motorcycle has a very round cross-sectional shape, and if a steel cord having rigidity on the compression side of the cord in the tire width direction is used, the tire becomes difficult to bend and the ground contact area is reduced. The organic fiber cord has low rigidity on the compression side of the cord, and there is no worry of reducing the ground contact area.

  Although not defined in claim 4, since the purpose of arranging the belt reinforcing layer is to eliminate the step at the end of the spiral belt, it is meaningless if the diameter of the cord is too thin. On the other hand, if the diameter of the cord is too thick, the cord has rigidity on the compression side of the cord even though it is an organic fiber. The cord diameter of the belt reinforcing layer is preferably 0.5 mm or greater and 1.2 mm or less.

  The invention according to claim 5 is characterized in that a buffer rubber layer having a thickness of 0.3 to 3 mm is disposed on the inner side in the tire radial direction of the belt reinforcing layer.

  According to the fifth aspect of the present invention, it is defined that the buffer rubber layer is disposed between the belt reinforcing layer having a cord angle of 85 to 90 degrees with respect to the tire circumferential direction and the spiral belt layer. This buffer rubber layer has an effect of suppressing wear of the tread shoulder portion. FIG. 6 shows the circumferential deformation of the tread when the tire turns at 50 degrees CA. As described above, the region A and the region C shown in FIG. 6 have different tread deformations in the circumferential direction. This is because the belt speed is different between the area C near the center of the ground contact shape and the area A near the tread edge of the ground contact shape. The pneumatic tire for a motorcycle has a large roundness in the cross section in the width direction. For this reason, the belt radius, which is the distance from the rotating shaft to the belt, is larger in the region C than in the region A. Accordingly, in the region C, the belt speed, that is, the belt speed until the tread moves away from the road surface after the tread contacts the road surface and the tread moves away from the road surface is higher. This is because the belt radius is obtained by multiplying the belt radius by the rotational angular velocity of the tire, and the rotational speed of the tire is the same in both the region A and the region C. Due to the speed difference in the circumferential direction of the belt, the tread is in the driving state in the region C near the center of the tire, and the braking state is in the region A near the end of the tread of the tire. Driving means that when a tire is cut in a circle along the equator direction, the deformation of the tread is sheared rearward in the tire traveling direction on the inner surface of the tread (the surface in contact with the skeleton member inside the tire) and touches the road surface. The tread surface is in a shearing state that is deformed forward in the tire traveling direction, and is a deformation that occurs when a driving force is applied to the tire. On the other hand, braking is the reverse of driving, and the deformation of the tread is a shearing state in which it is sheared forward on the tire inner side (belt) and deformed rearward on the tread surface that is in contact with the road surface. When the tires move. The deformation of the circumferential tread occurs only when the tire rolls in an idle state without receiving driving force or braking force. Then, due to the shear deformation in the circumferential direction, the tread easily slips from the road surface in the region A and the region C, and wear progresses. Such excessive deformation during turning tends to cause uneven wear on the shoulder portion of the tire, so it is better not to have such deformation.

  When the cushioning rubber layer is provided as in claim 5, the cushioning rubber layer shears and deforms in the circumferential direction, so that the above-described driving deformation and braking deformation are substituted for the tread, and the tread is deformed in the circumferential direction. Alleviated. On the other hand, since a belt reinforcing layer, which is a belt (90-degree belt) along the width direction, is disposed on the outer side in the tire radial direction of the buffer rubber layer, it is not easily sheared in the width direction. Therefore, the buffer rubber layer does not take over the deformation of the tread in the width direction, and the transverse shear deformation of the tread remains large even if the buffer rubber layer is arranged. That is, the shock absorbing rubber layer shoulders only the deformation in the circumferential direction and reduces the circumferential deformation of the tread to prevent uneven wear, while the lateral deformation of the tread remains large without replacing the shoulder in the width direction. There is an effect of keeping the lateral force high.

  By using the same material as the coating rubber of the spiral cord or the coating rubber of the 90-degree belt, the cushioning rubber layer is effective without causing cracks between the cushioning rubber layer and these belt members. In addition, when soft rubber (rubber having a low elastic modulus) is used for the buffer rubber layer, the effect of suppressing wear is increased in order to replace more tread deformation.

  In the invention according to claim 6, the side reinforcing member in which organic fiber cords or steel cords within an angle range of 0 to 20 degrees with respect to the tire circumferential direction are arranged on the sidewall portion is 20% of the sidewall height. It arrange | positions in the range of 100% or less.

  In the present invention, a spiral belt is not wound around the tread shoulder portion. Therefore, the centrifugal force is easily expanded when the tread shoulder portion rotates at a high speed. If a member having an angle of 0 degrees to 20 degrees with respect to the tire circumferential direction (tire equator direction) is disposed on the sidewall portion of the tire as in claim 6, the sidewall portion is less likely to expand due to centrifugal force, and the tread About a shoulder part, since the member which prevents expansion | swelling can be arrange | positioned on the both sides, it comes to be able to prevent expansion | swelling by a centrifugal force. That is, for the tread shoulder portion where the spiral belt is not wound, the shoulder side spiral belt member prevents expansion near the center, and the side reinforcing member disposed on the side wall portion prevents expansion due to centrifugal force at the tread end portion. Can do. When this side reinforcing member is not disposed in the sidewall portion, the shoulder side spiral member is a member that prevents centrifugal expansion and is in a cantilever state, but if this side reinforcing member is disposed in the sidewall portion, the shoulder side Expansion can be prevented on both sides of the spiral belt member and the side reinforcing member, and expansion of the tread shoulder portion can be prevented in a state where both sides are supported. In particular, motorcycle race tires and the like often have a speed of 150 km or more during a large CA, and are particularly effective in such cases.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the pneumatic tire for motorcycles which suppressed the fall of the tire performance by having provided the spiral belt member.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals, and description thereof is omitted. In the following description, the width of the belt or the like is the width in the peripheral direction.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, the pneumatic tire 10 for a motorcycle according to the present embodiment includes a pair of left and right bead portions 12 and a carcass layer 14 extending from the bead portion 12 in a toroidal shape.

The carcass layer 14 straddles the bead core 11 of the bead portion 12 in a toroidal shape. The carcass ply (body ply) constituting the carcass layer 14 may be a single layer or a plurality of layers. When the carcass layer 14 is constituted by two carcass plies, the direction of the cords constituting the carcass ply may be a radial direction (a direction in which the angle with respect to the tire circumferential direction is 90 degrees). A bias structure in which plies having an angle (cord angle) formed by a cord with respect to a direction in a range of 30 degrees to 80 degrees may be used in an intersecting manner. Further, in this case, each carcass ply is often configured by twisting nylon fibers into nylon cords arranged at predetermined intervals. FIG. 1 illustrates an example in which the carcass layer 14 is composed of one carcass ply 14A.
The end of the carcass ply 14A is locked by a bead core 11, and a bead wire 13 is sandwiched from both sides. The end of the carcass ply 14A may be wound up so that the bead core 11 is folded back.

  In addition, the pneumatic tire 10 for a motorcycle includes a spiral belt layer 20 on the inner side in the tire radial direction of the crown portion 14 </ b> C of the carcass layer 14. The spiral belt layer 20 has a cord angle in a range of 0 to 5 degrees with respect to a tire circumferential direction of a belt-like rubber-coated cord layer 21 formed by embedding a single wire or a plurality of parallel cords in a coated rubber. In this way, it is wound in a spiral shape. When the tread surface distance from the tire center CL to the tread end T (that is, ½ of the width in the peripheral direction of the tread portion 18) is L, the distance W3 from the tire center CL along the tread surface is 0.65L to This spiral belt layer 20 exists only in the range up to the position of 0.85L.

  The spiral belt layer 20 is divided into three parts: a center side spiral belt member 20C straddling the tire center portion, and a pair of shoulder side spiral belt members 20L and 20R respectively disposed on the tread shoulder side on both sides in the tire width direction. Configured.

  Adjacent ends of the center side spiral belt member 20C and the shoulder side spiral belt members 20L, 20R are separated from each other by a distance D in the range of 0.1L to 0.42L along the tread surface.

  The distance W1 along the tread surface from the tire center CL to the end 20CE of the center-side spiral belt member 20C is in the range of 0.08L to 0.25L. Furthermore, the distance W2 along the tread surface from the tire center CL to the respective end portions 20LI and 20RI on the tire center side of the shoulder side spiral belt members 20L and 20R is in the range of 0.25L to 0.5L. .

Furthermore, the pneumatic tire 10 for a motorcycle includes a crossing belt layer 24 including two crossing belt members 25A and 25B on the outer side in the tire radial direction of the crown portion 14C of the carcass layer 14. The cross belt members 25A and 25B include organic fiber cords that cross each other and have a cord angle of 30 degrees or more and less than 80 degrees with respect to the tire circumferential direction. Further, the crossing belt layer 24 is disposed with a width of 90% or more of the total tread width 2L so as to cover at least a part of the range from the width direction end 20E to the tread end T of the spiral belt layer 20.
A tread portion 18 is provided on the outer side of the cross belt layer 24 in the tire radial direction.

As described above, in the present embodiment, the spiral belt layer 20 is present so that the spiral belt layer 20 exists only within the distance W3 along the tread surface from the tire center CL up to the position of 0.65L to 0.85L. A width of 20 is specified.
Here, the tread portion near the end portion of the tread serves as a ground contact portion when turning during a large camber. Therefore, in the tread portion where the spiral belt layer 20 is not formed, the skeleton member can be positively extended in the tire circumferential direction, and in the tread portion where the spiral belt layer 20 is formed, the skeleton member is This prevents the tire from extending in the tire circumferential direction in the contact area.

  As a result, the pneumatic tire 10 for a motorcycle can maintain a high steering stability performance during high-speed traveling and can improve the steering stability performance (traction performance) during a turn when the vehicle body is greatly tilted. Further, wear of the shoulder portion can be suppressed.

  The spiral belt layer 20 is composed of a spiral belt member divided into three parts. The adjacent end portions of the center side spiral belt member 20C and the shoulder side spiral belt members 20L and 20R are separated by a distance D within the range of 0.1L to 0.42L along the substantially arc shape of the tread surface. ing. Thereby, the flexibility of the skeleton member is given, and it is easy to bend when the tire goes straight. That is, by forming the region 26 where the spiral belt layer 20 does not exist in the vicinity of the ground contact end where the deformation of the tread is most severe, the tire is easily bent and the riding comfort performance is improved.

  The distance W1 along the tread surface from the tire center CL to the end 20E of the center-side spiral belt member 20C is in the range of 0.08L to 0.25L. Since the center side spiral belt member has a width of 0.08 L or more, the effect of preventing the tire from expanding by centrifugal force can be sufficiently exhibited. Further, since it is 0.25 L or less, there is no spiral belt member at the most severely deformed ground contact end, so that the belt skeleton of the tread portion 18 is easily bent, and riding comfort performance is ensured.

  Further, a distance W2 along the tread surface from the tire center CL to the end 20LI on the tire center side of the shoulder side spiral belt member 20L (this distance is the end on the tire center side of the shoulder side spiral belt member 20R from the tire center CL). The same as the distance along the tread surface to the portion 20RI) is in the range of 0.25L to 0.5L. Since it is 0.25L or more, the spiral belt member does not exist at a portion where the deformation is greatest in the cross section of the tire when traveling straight, so that riding comfort performance when traveling straight is ensured. Moreover, since it is 0.5 L or less, the width | variety of the spiral belt member in the tread shoulder part TS does not become too narrow.

  Further, a crossing belt layer 24 is disposed separately from the carcass plies 15A and 15B. As a result, the substantial thickness of the tread portion 18 is increased by the thickness of the crossing belt layer, so that a larger thickness from the spiral belt layer 20 to the tread surface can be secured.

[Second Embodiment]
Next, a second embodiment will be described. As shown in FIG. 2, the pneumatic tire 30 for a motorcycle according to this embodiment has the arrangement positions of the cross belt layer 24 and the spiral belt layer 20 reversed as compared with the first embodiment, and further, the cross belt layer 24. A belt reinforcing layer 32 is provided between the belt and the tread portion 18. The belt reinforcing layer 32 includes an organic fiber cord whose cord angle with respect to the tire circumferential direction is in the range of 85 to 90 degrees, and is adjacent to the inner side in the tire radial direction of the tread portion 18 with a width of 90% or more of the total tread width 2L. Are arranged as follows.
Further, side reinforcing members 36 having a thickness in the range of 0.3 to 3 mm are disposed on the side wall portions 34 on both sides in the tire width direction.

  By providing the belt reinforcing layer 32, even if the rigidity of the skeleton member of the tire changes suddenly at the boundary between the portion where the spiral belt layer is present and the portion where the spiral belt layer is not present, this portion is grounded to the tread portion 18. When the end gets over, the rider is prevented from feeling a sense of incongruity due to the tire steps.

  Further, by arranging the side reinforcing member 36, the side reinforcing member 36 is arranged on the side wall portion 34, so that the shoulder side spiral belt members 20 </ b> L and 20 </ b> R and the side reinforcing member 36 are expanded on both sides. The tread shoulder portion TS can be prevented from expanding in a both-sided state.

[Third Embodiment]
Next, a third embodiment will be described. As shown in FIG. 3, in the pneumatic tire 40 for a motorcycle according to the present embodiment, a buffer rubber layer 42 is disposed on the inner side in the tire radial direction of the belt reinforcing layer 32 as compared with the second embodiment.
Thereby, wear of the tread shoulder portion TS is suppressed.

[Fourth Embodiment]
Next, a third embodiment will be described. As shown in FIG. 4, in the pneumatic tire 50 for a motorcycle according to the present embodiment, the carcass layer 14 is constituted by two carcass plies 15A and 15B. The carcass plies 15A and 15B are arranged so as to cross each other.

A spiral belt layer 20 is disposed outside the carcass layer 14 in the tire radial direction. As described above, the spiral belt layer 20 includes the center side spiral belt member 20C and the pair of shoulder side spiral belt members 20L and 20R.
A belt reinforcing layer 32 is disposed on the outer side in the tire radial direction of the spiral belt layer 20. The belt reinforcing layer 32 is adjacent to the tread portion 18. Therefore, the motorcycle pneumatic tire 50 has a simple configuration in which the crossing belt layer 24 (see FIG. 1) is not disposed.

<Test example>
In order to confirm the effect of the present invention, the present inventor made 18 examples of pneumatic tires for motorcycles according to the present invention (hereinafter referred to as Examples 1 to 18) and 3 examples of pneumatic tires for motorcycles for comparison ( Hereinafter, performance tests were performed on two examples of conventional pneumatic tires for motorcycles (hereinafter referred to as Conventional Examples 1 and 2) to evaluate the performance.

  All tire sizes are 190 / 50ZR17. In each tire, one carcass ply is disposed in the carcass layer. In each tire, no groove is arranged in the tread portion.

(Examples 1-12)
Examples 1 to 12 are examples of the pneumatic tire 10 for a motorcycle according to the first embodiment, and are pneumatic tires for a motorcycle having the structure shown in FIG. The cord material of the carcass plies 15A and 15B is nylon. In this embodiment, nylon fibers are twisted to form a 0.6 mmφ cord, which are arranged in parallel at a driving interval of 65/50 mm, and formed into a sheet shape with unvulcanized rubber is used as a carcass ply. The cord angle of this nylon cord is 90 degrees (radial direction) with respect to the tire equator direction.

The spiral belt layer 20 is formed on the outer side in the tire radial direction of the carcass layer 14 by the presence of a total of three divided spiral belt members, that is, the center side spiral belt member 20C and the shoulder side spiral belt members 20L and 20R. Yes. Each spiral belt member is a belt having an angle of 0 degrees to 5 degrees with respect to the tire equator direction. One or a plurality of cords are covered with rubber, and this is spirally wound around the tread portion in the tire manufacturing process. Thus, it is formed by wrapping around the equator so that it is almost parallel. In this test example, the spiral layer was formed by twisting fibers of aromatic polyamide (trade name: Kevlar) to a diameter of 0.7 mm so that the driving interval was 60/50 mm. The spiral belt may be made of steel. For example, the spiral belt is formed by winding a steel cord twisted in a 1 × 3 type of a steel single wire having a diameter of 0.21 mm at a spacing of 30/50 mm. It is possible. In this test example, an organic fiber (aromatic polyamide) cord was used as a spiral belt.
The total tread width 2L is 240 mm. In this test example, what changed W1, W2, and W3 as parameters was prepared as Examples 1-12.

  On the outer side in the tire radial direction of the spiral belt layer 20 composed of three spiral belt members, there is an intersection belt layer 24 composed of two intersecting belt members 25A and 25B. When the crossing belt layer 24 was provided, aromatic polyamide (trade name: Kevlar) fibers twisted to a diameter of 0.7 mm were arranged so that the driving interval was 40/50 mm. The two were arranged so as to cross each other so as to form an angle of 60 degrees with respect to the equator direction. The width of the cross belt member 25B of the first sheet (inner side in the tire radial direction) is 240 mm, and the width of the cross belt member 25A of the second sheet (outer side in the tire radial direction) is 230 mm.

  A tread portion 18 having a thickness of 7 mm is disposed on the outer side of the crossing belt layer 24 in the tire radial direction.

(Conventional example 1)
Conventional example 1 is shown in FIG. In the first conventional example, as compared with the first example, one spiral belt layer 80 that is not divided is disposed instead of the spiral belt layer 20 (see FIG. 1). The width of the spiral belt layer 80 is 2 L (240 mm).

(Comparative Example 1)
In Comparative Example 1, as in Conventional Example 1, an undivided spiral belt layer is disposed. Comparative Example 1 is different from Conventional Example 1 in the width of the spiral belt layer. In Comparative Example 1, the width of the spiral belt layer is 180 mm, and the distance along the tread surface from the tire center to the end of the spiral belt layer is 0.75L.

(Example 13)
In Example 13, as compared with Example 1, the position of the spiral belt layer 20 and the position of the crossing belt layer 24 are reversed.

(Example 14)
In Example 14, compared with Example 13, a belt reinforcing layer (90-degree belt) 32 (see FIG. 2) is arranged on the outer side in the tire radial direction of the spiral belt layer. The belt reinforcing layer 32 is a Kevlar belt, and a cord made of twisted fiber of aromatic polyamide (trade name: Kevlar) and having a diameter of 0.7 mm is formed at 90 degrees with respect to the tire equator direction. Arranged at 50/50 mm driving distance. The width of the belt reinforcing layer 32 is 240 mm.

(Example 15)
In Example 15, compared with Example 14, the inner side of the belt reinforcing layer 32 in the tire radial direction is in contact with the belt reinforcing layer 32, that is, the spiral belt layer 20 (the center side spiral belt member 20C and the shoulder side spiral belt member). 20L, 20R) and a belt reinforcing layer 32, a buffer rubber layer 42 (see FIG. 3) having a thickness of 0.5 mm is disposed.

(Example 16)
In Example 16, compared with Example 14, as shown in FIG. 2, the side wall 34 was wound in the same direction as the tire equator direction (that is, the center side spiral belt member 20C and the shoulder side spiral belt members 20L, 20R). A narrow member of the Kevlar spiral (wound in the same direction as the above) is arranged as the side reinforcing member 36. The width of the side reinforcing member 36 is 20 mm, and 20 cords twisted with Kevlar having a diameter of 0.7 mm are driven. The arrangement position of the side reinforcing member 36 is in the vicinity of the tire maximum width, and more specifically, the side reinforcing member 36 is arranged at the center position in the height direction of the sidewall portion 34 (intermediate position in the height direction). In the present test example, the side reinforcing member 36 is disposed so as to be symmetrical.

(Example 17)
In Example 17, as shown in FIG. 4, the carcass layer 14 composed of the two carcass plies 15 </ b> A and 15 </ b> B crossed with each other is provided, and no crossing belt layer is disposed. The ends of the carcass plies 15A and 15B are locked by the bead core 11, and the bead wires are sandwiched from both sides. Nylon cords were twisted to form a cord with a diameter of 0.6 mm, which were arranged in parallel at an interval of 65/50 mm, and used as a carcass ply in a sheet form with unvulcanized rubber. The two carcass plies 15A and 15B are arranged so as to cross each other. The cord angle with respect to the tire equator direction is 50 degrees at the tire center portion.

  A spiral belt layer 20 including a center side spiral belt member 20C and a pair of shoulder side spiral belt members 20L and 20R is disposed outside the carcass layer 14 in the tire radial direction. Unlike Examples 1 to 16, the spiral belt layer 20 is made of steel cord. In Example 17, a spiral belt layer 20 was formed by winding a steel cord twisted by a 1 × 3 type steel single wire having a diameter of 0.21 mm in a spiral shape at an interval of 50/50 mm.

  In Example 17, a belt reinforcing layer (90-degree belt) 32 is disposed on the outer side in the tire radial direction of the spiral belt layer 20. The belt reinforcing layer 32 is a belt made of Kevlar, and an aromatic polyamide fiber twisted to a diameter of 0.7 mm is arranged so that the driving interval is 50/50 mm. When the belt reinforcing layer 32 is disposed, the cord angle with respect to the tire equator direction is 90 degrees and the width is 240 mm.

(Conventional example 2)
Compared with Example 17, the prior art example 2 has a spiral belt layer made up of one spiral belt member instead of the spiral belt layer 20 and no belt reinforcing layer. The width of the arranged spiral belt layer is 2 L (240 mm). A tread portion having a thickness of 7 mm is formed on the outer side of the spiral belt layer in the tire radial direction.

(Example 18)
In the eighteenth embodiment, a buffer rubber layer 42 (see FIG. 3) is disposed as compared with the seventeenth embodiment. A rubber layer having a thickness of 0.7 mm was disposed on the inner side in the tire radial direction of the belt reinforcing layer 32 of Example 17 to obtain a buffer rubber layer 42. The rubber material of the buffer rubber layer 42 is the same as the rubber material of the belt reinforcing layer 32.

The above tire conditions are summarized in Tables 1 and 2.

(Test method and evaluation results)
In this test example, in order to evaluate how much the traction performance is improved when the target vehicle body is tilted, a specified test was conducted as follows using a drum.

In this test example, the tire internal pressure was set to 240 kPa after being incorporated into the standard rim for all tires. Here, the standard rim refers to a standard rim in an applicable size defined in the 2006 YEAR BOOK issued by JATMA.
As a testing machine, paste # 40 coarse sandpaper on a steel drum with a diameter of 3 m and make the sandpaper look like a road surface. Then, the drum is rolled at 100 km / h, and the tire is pressed against the sandpaper with a camber angle of 50 degrees and a load of 1500 N from above the drum. In this test example, a chain that transmits power to the rotating shaft is hung on the tire so that a driving force can be applied. In this test example, a driving force was applied using a motor.

  In this test example, the tire is rotated at 100 km / h, and the driving force is applied to accelerate the tire linearly to 120 km / h in a time of 2 seconds. At that time, since the drum is rolling at 100 km / h, the driving force is applied to the tire, and the traction can be measured when the vehicle body is tilted. The force acting on the tire is read by a force sensor installed at the center of the tire wheel.

When this read force is drawn as Fx (force acting in a direction parallel to the tire traveling direction) on the horizontal axis and Fy (force acting in a direction perpendicular to the tire traveling direction) on the vertical axis, as shown in FIG. Waveforms P and Q can be obtained. The waveforms P and Q are called friction ellipses. The intercept of Fy at Fx = 0 indicates a pure lateral force at a driving force of 0, which is a force called a camber thrust. In this test example, the camber thrust, which is a section of Fy, and the peak chip of traction were evaluated. In this test example, the grip performance of a tire in a traction state is evaluated by applying a driving force to the tire to accelerate the rotation of the tire. With time, the waveform of the graph moves in the positive direction of Fx. The maximum value of Fx can be said to be an index of traction grip.
In this test example, the maximum value of Fx in Conventional Example 1 was set as an index 100, and the performance (traction performance) of other tires was evaluated using an index serving as a relative evaluation. The evaluation results are also shown in Tables 1 and 2.

  Next, a pilot performance comparison test using an actual vehicle was conducted. Since each tire used in this test example was a tire for the rear, the front tire was always kept as before, and the actual tire test was performed with the rear tire replaced. The test method and evaluation method are described below.

  The test tire is mounted on a 1000cc sports-type motorcycle and run on the test track. The ride comfort and handling stability (cornering performance) are comprehensively evaluated by a 10-point method based on the feeling of the test rider. . The course was intensely conscious of motorcycle racing, and the maximum speed reached 220 km / h.

The evaluation items are the following three. The evaluation results are also shown in Tables 1 and 2.
1) Ride comfort when traveling straight (evaluated by running on highway seams and rough roads)
2) Traction performance when turning (according to comprehensive judgment of acceleration performance from a state where the vehicle body is largely tilted at a speed of about 100 km / h, and turning performance at high-speed corners at a speed of 150 km / h or more)
3) Continuity when the bike is turned down when turning (the performance of not causing abnormal behavior when the bike is pushed down)

  Moreover, the partial wear state of the tire shoulder part when 10 laps of test courses were run was confirmed. That is, the amount of wear of the tire shoulder portion was measured, and the amount of wear of another tire when the amount of wear of the tire of Conventional Example 1 was taken as an index 100 was determined by an index that was a relative evaluation. This index is also shown in Tables 1 and 2. Regarding the amount of wear, the smaller the index, the less the wear and the better.

From the above evaluation results, the present inventor conducted the following consideration.
(1) Effect of the width of the spiral belt at the shoulder portion Effect of the width of W3 By comparing Conventional Example 1, Examples 1 to 3, and Comparative Examples 2 and 3, the effect of the width of the spiral belt layer (the effect of the width by W3) I understand.

First, in all the examples, the ride comfort is better than the conventional example. This is because the spiral belt is divided into three so that the belt can bend easily when going straight.
Regarding the effect of the width of W3, at 70 mm, the traction index is as small as 101, and the effect is small. This is because the grounding width is 60 mm from the center part to the 120 mm tread end in the grounding state at the time of large CA (see FIG. 6), and the 70 mm position is at the end of the grounding part. This is because there is almost no spiral belt near the grounding part.

  At 110 mm, the effect of improving traction is small. This is because the spiral belt is almost wound around the grounding portion, and the belt is difficult to extend in the circumferential direction at the end of the tread.

  90 mm (0.75 L) has the highest traction improvement effect, followed by 80 mm (0.67 L) and 100 mm (0.83 L). From the above, it is considered that the width of W3 is preferably 0.7L or more and 0.9 or less. Moreover, Preferably, it is considered as 0.65L-0.85L.

  Comparing Comparative Example 1 and Example 1, Example 1 has a higher traction performance score of 1 point in the actual vehicle test. As a result of confirmation with the evaluation rider, it was evaluated that Example 1 had better gap absorbability of the tire when CA was large, such as 50 degrees CA, that is, the tire was reasonably soft and captured the road surface. This is because in Example 1, there is a gap around which a 20 mm spiral belt is not wound, and this is because the portion 20 to 40 mm from the tread center has a role like a sidewall in the turning shown in FIG. This is because this portion is easily bent, so that the tire is easily deformed and the contact area is increased. Therefore, the tire felt soft and was excellent in gap absorption. As described above, it was found that by dividing the spiral into three, the turning performance at the time of large CA is improved in addition to the improvement of the riding comfort performance at the time of straight traveling.

(2) Effect of the width of the spiral belt in the center portion Effect of the width of W1 By comparing Example 1 and Examples 4 to 7, the effect of the width of the spiral belt in the center portion (effect of the width of W1) can be understood.
Although Example 4 is 5 mm, the traction index is slightly lower than other tires. This is because the spiral belt disappears in the center portion, the rigidity of the belt is lowered, the tire is easily twisted, and the rigidity of the tire frame member is insufficient when traction is applied. In addition, although the ride performance when traveling straight is very soft, the evaluation after the vibration was a little worse. Moreover, since the width of the center tag against the protruding expansion of the center at high speed rolling is small at 5 mm (10 mm on both sides), it is considered that a slightly larger width is better when assuming ultra high speed rolling.

  On the other hand, Example 7 has a width of 40 mm, but the riding comfort performance is worse than the others. This is because, in the cross section of the tire shown in FIG. 7, the spiral belt member is wound around the grounded region S, and the spiral belt member is also present at the ground deformation end SE having the largest deformation. From the above, W2 is preferably 0.08L or more and 0.25L or less.

(3) Effect of Spiral Belt Width of Shoulder Part Effect of Width of W2 By comparing Conventional Example 1 and Examples 8 to 12, the effect of the width of the spiral belt (effect of the width of W2) can be understood.

In Example 8, the spiral end portion of the shoulder portion starts to be wound from a position of 20 mm, but the riding comfort performance is deteriorated. This is because the spiral belt of the shoulder portion is disposed in the portion J where deformation is greatest in the tire cross section shown in FIG. In Example 9, the improvement in riding comfort performance is also great, and it can be determined that W2 of 30 mm or more is good.
On the other hand, when the winding position is 60 mm or 70 mm as in Examples 11 and 12, the traction index decreases. This is because the width of the spiral belt in the shoulder portion becomes too narrow and the in-plane shear rigidity of the belt is lowered.

  From the above, the value of W2 is preferably 0.25L to 0.5L. More preferably, it is the range of 0.3L-0.45L.

(3) Relationship Between Positions of Crossing Belt and Spiral Belt From the comparison between Example 1 and Example 13, it can be seen that it is preferable that the spiral belt is disposed radially inward of the crossing belt. In Example 13 in which the spiral belt is arranged on the outer side in the radial direction than the crossing belt, the rider feels uncomfortable when tilting down. This is because a step is felt when the grounding shape moves between the boundary where the spiral belt is wound and the portion where the spiral belt is not wound. On the other hand, when the cross belt is disposed on the outer side in the radial direction with the spiral belt as the inner layer, the wide cross belt wraps the step of the spiral belt, making it difficult to feel the step. Therefore, the rider's evaluation is higher when the spiral belt is wound on the inner layer.

(4) Effect of 90-degree belt The comparison of Example 13 and Example 14 shows the effect of the 90-degree belt. The continuity of the falling down of the actual vehicle is improved by the 90 degree belt. This is because the step of the spiral belt is alleviated in the same manner as the previous crossing belt is wound on the outer side in the radial direction of the spiral belt.

(5) Effect of shock absorbing rubber layer The effect of the shock absorbing rubber layer can be understood from comparison between Example 13, Example 14, and Example 15.
The comparison between Example 14 and Example 15 is whether or not there is a buffer rubber layer. In Example 15 with the buffer rubber layer, the amount of wear is very small. This is because, as described above, the buffer rubber layer is sheared and deformed in the circumferential direction to take over the deformation of the tread, and the excessive shear deformation in the circumferential direction of the tread is reduced. Therefore, the tread is less likely to slip from the road surface, and the amount of wear is reduced. Further, since unnecessary deformation in the circumferential direction of the tread is reduced, useless movement is eliminated and the tread can contribute to the grip. That is, in FIG. 6, the region A is braking, the region B is neutral (no deformation), the region C is driving, and the deformation state of the tread in the circumferential direction is described. When traction is added to this, the regions A to C are also subjected to driving deformation by traction. At this time, the region C is originally in a driving state, and the driving deformation is further strengthened by traction (driving force), and the force is most exerted. On the other hand, since the region A is in a braking state, it first returns to a neutral state by traction, and then shifts to driving deformation. Therefore, the amount of generated driving force is smaller in the region A than in the region C. If traction is further applied, the amount of driving force generated in the region A increases, but the region C slips, and the amount of traction generated reaches a peak. Also, sliding generally decreases the friction coefficient (it is well known that the dynamic friction coefficient is smaller than the static friction coefficient). Therefore, generation of driving force becomes inefficient when slipping.

  When the buffer rubber layer is provided as in the fifteenth embodiment, the difference in deformation between the original region A and region C is small. Therefore, when the region C becomes a large driving state due to traction, the region A can also be in a driving state to some extent. This is an effect obtained by providing a buffer rubber layer to alleviate unnecessary circumferential deformation of the regions A and C.

  When Example 13 and Example 14 are compared, although not as much as Example 15, there is an effect of reducing the amount of wear and an effect of improving the traction index. This is because the 90-degree belt (belt reinforcing layer) itself can be deformed in the circumferential direction in the same manner as the buffer rubber layer. The 90-degree belt has a coating rubber disposed around the cord, and the cord itself and the surrounding coating rubber can realize such deformation.

(6) Effect of Side Reinforcement Member From the comparison between Example 14 and Example 16, the effect of a member (side reinforcement member) having a cord angle of 0 to 20 degrees arranged in the sidewall portion can be seen.

  Placing members on the sidewalls improved the traction score of the actual vehicle by 1 point. When the details were confirmed with the evaluation rider, it was found that the tire of Example 16 had rigidity and a sense of stability, particularly when turning at a high speed exceeding 150 km / h. By winding the spiral belt member around the sidewall portion, the expansion of the end portion of the tread where the spiral belt does not exist can be suppressed from both sides, and the steering stability performance is improved.

(7) Tires in which in-plane shear rigidity of the tread frame member is ensured by crossing the plies without belts Conventional Example 2, Example 17, and Example 18 are carcass ply ( The tire is such that the rigidity of the skeleton member of the tread portion is ensured by crossing the body plies). The effect of the present invention can be confirmed in the same manner as the tire in which the cross belt is disposed.
Compared to Conventional Example 2, Example 17 has improved riding comfort performance and a high traction index. Moreover, it turns out that abrasion is also suppressed. Further, Example 18 is a tire having a cushioning rubber layer disposed thereon, but as in Example 15, not only the traction index is improved and the traction grip during turning is improved, but also the wear resistance performance is improved. ing.

  In addition, the point of using the steel for the spiral belt, and the point that the side wall part is hard because the ply was interlaced, the overall score of ride comfort performance is lower.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

1 is a tire radial direction cross-sectional view of a motorcycle pneumatic tire according to a first embodiment. It is a tire radial direction sectional view of the pneumatic tire for motorcycles concerning a 2nd embodiment. It is a tire radial direction sectional view of the pneumatic tire for motorcycles concerning a 3rd embodiment. It is a tire radial direction sectional view of the pneumatic tire for motorcycles concerning a 4th embodiment. It is explanatory drawing explaining the force measured by the test example. It is explanatory drawing which shows the grounding state at the time of the large camber of the pneumatic tire for motorcycles. It is explanatory drawing which shows the grounding state at the time of the straight advance of the pneumatic tire for motorcycles. FIG. 6 is a tire radial direction cross-sectional view of a conventional pneumatic tire for a motorcycle.

Explanation of symbols

10 Pneumatic tire for motorcycle 14 Carcass layer 14A Carcass ply 14C Crown portion 15A, B Carcass ply 18 Tread portion 20 Spiral belt layer (belt layer, spiral belt layer)
20C Center side spiral belt member 20L, R Shoulder side spiral belt member 20CE End portion 20E End portion 20LI, RI End portion 21 Rubber-coated cord layer 24 Cross belt layer 25A, B Cross belt member 20E Width direction end CL Tire center D Interval TS tread shoulder portion T tread end W1 distance W2 distance W3 distance 30 motorcycle pneumatic tire 32 belt reinforcing layer 34 sidewall portion 36 side reinforcing member 40 motorcycle pneumatic tire 42 shock absorbing rubber layer 50 motorcycle pneumatic tire 80 spiral belt layer

Claims (6)

A belt layer and a tread portion are sequentially provided on the outer side in the tire radial direction of the crown portion of the carcass layer formed of one or more carcass plies,
The belt layer spirals a belt-like rubber-coated cord layer formed by embedding a single wire or a plurality of parallel cords in a coated rubber so as to form a cord angle within a range of 0 to 5 degrees with respect to the tire circumferential direction. In a pneumatic tire for a motorcycle having at least one spiral belt layer wound in a shape,
When the tread surface distance from the tire center to the tread edge is L, the spiral belt layer exists only within the range from the tire center to the position of 0.65L to 0.85L along the tread surface.
The spiral belt layer includes a center-side spiral belt member straddling the tire center, and a pair of shoulder-side spiral belt members disposed on the tread shoulder side on both sides in the tire width direction,
Adjacent ends of the center-side spiral belt member and the shoulder-side spiral belt member are separated by an interval in the range of 0.1 L to 0.42 L along the tread surface,
The distance along the tread surface from the tire center to the end of the center side spiral belt member is in the range of 0.08L to 0.25L,
A pneumatic tire for a motorcycle, wherein a distance along a tread surface from a tire center to an end of the shoulder side spiral belt member on a tire center side is within a range of 0.25L to 0.5L. In addition to the spiral bell collar layer, an intersecting belt layer composed of at least two intersecting belt members made of organic fibers that intersect each other is disposed,
The pneumatic tire for a motorcycle according to claim 1, wherein a cord angle of the crossing belt member with respect to a tire circumferential direction is within a range of 30 to 80 degrees.   The pneumatic tire for a motorcycle according to claim 2, wherein all belt members constituting the spiral belt layer are arranged on the inner side in the tire radial direction than the crossing belt layer.   A belt reinforcing layer including an organic fiber cord whose cord angle with respect to the tire circumferential direction is within a range of 85 to 90 degrees is disposed between the spiral belt layer and the tread portion with a width of 90% or more of the total tread width 2L. The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the pneumatic tire is a motorcycle.   The pneumatic tire for a motorcycle according to claim 4, wherein a shock absorbing rubber layer having a thickness in the range of 0.3 to 3 mm is arranged on the inner side in the tire radial direction of the belt reinforcing layer.   Side reinforcement members in which organic fiber cords or steel cords in an angle range of 0 to 20 degrees with respect to the tire circumferential direction are arranged in the sidewall portion are arranged in a range of 20% to 100% of the sidewall height. The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein the pneumatic tire is a motorcycle.

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