JP6196548B2 - Motorcycle tires - Google Patents

Description

  The present invention relates to a motorcycle tire having improved drainage performance and steering stability performance in a well-balanced manner.

  A motorcycle tire having excellent drainage performance and steering stability performance is desired. In order to improve drainage performance of motorcycle tires, for example, it has been proposed to provide a main groove having a large groove volume in the tread portion.

  However, the motorcycle tire as described above has a problem that the rigidity of the tread portion is reduced and the steering stability performance is deteriorated. Related technologies include the following.

Japanese Patent Laid-Open No. 10-264611

  The present invention has been devised in view of the actual situation as described above. Based on the improvement of the tie bar provided in the main groove, a motorcycle tire having improved drainage performance and steering stability performance in a well-balanced manner is provided. The main purpose is to provide.

  The present invention is a motorcycle tire having a tread portion, wherein the tread portion is provided with at least two main grooves extending continuously in a tire circumferential direction, and each of the main grooves has a groove. At least one first tie bar having a raised bottom is provided, and the first tie bar provided in one main groove is different from the first tie bar provided in another main groove in the tire circumferential direction. It is provided in the position.

  The motorcycle tire according to the present invention is in a 50% load-loaded state in which a rim is assembled on a regular rim and filled with a regular internal pressure, and 50% of the regular load is loaded and grounded on a plane with a camber angle of 0 degrees. At least one first tie bar is included in each main groove on the ground contact surface of the tread portion.

  In the motorcycle tire according to the present invention, the main groove includes a pair of shoulder main grooves extending most on the tread end side, and the tread portion further includes an outer side in the tire axial direction of the shoulder main groove. A plurality of shoulder inclined grooves extending in a direction crossing the shoulder main groove are provided, and each shoulder inclined groove is provided with at least one second tie bar having a groove bottom raised.

  The motorcycle tire according to the present invention is a 50% load-inclined state in which a rim is assembled on a regular rim and filled with a regular internal pressure, and 50% of a regular load is loaded and grounded on a plane at a camber angle of 30 degrees. In the ground contact surface of the tread portion, at least one second tie bar is included in each shoulder lateral groove.

  In the motorcycle tire according to the present invention, the second tie bar provided in one shoulder inclined groove is provided in the other shoulder inclined groove on the contact surface of the tread portion in the inclined state with the 50% load load. The second tie bar is provided at a different position in the tire axial direction.

  In the motorcycle tire according to the present invention, a groove depth of the main groove at the first tie bar is 50% to 70% of a maximum groove depth of the main groove, and the shoulder inclined groove has the first groove. The groove depth at 2 tie bars is 50% to 70% of the maximum groove depth of the shoulder inclined groove.

  In the motorcycle tire according to the present invention, the first tie bar and the second tie bar have a length along the longitudinal direction of the groove of 4 to 10 mm.

  In the motorcycle tire of the present invention, a plurality of main grooves are provided in the tread portion, and each main groove is provided with at least one first tie bar having a groove bottom raised. Such a tie bar increases the rigidity of the tread portion by increasing the volume of the tread portion, and suppresses closing of the main groove due to a force from the road surface. This suppresses deformation of the tread portion to secure a ground contact area and improves steering stability performance. Further, a reduction in the groove volume of the main groove due to the closing of the main groove is prevented. Therefore, in the motorcycle tire of the present invention, high drainage performance and steering stability performance are improved in a well-balanced manner.

  Further, the first tie bar provided in one main groove is provided at a position different from the first tie bar provided in the other main groove in the tire circumferential direction. Thereby, the rigidity and drainage performance of the tread portion are easily made uniform over the tire circumferential direction. Therefore, the motorcycle tire of the present invention further improves the drainage performance and steering stability performance in a well-balanced manner.

1 is a cross-sectional view of a motorcycle tire showing an embodiment of the present invention. FIG. 2 is a development view of a tread portion of the motorcycle tire of FIG. 1. (A) is sectional drawing of the longitudinal direction of the main groove containing a 1st tie bar, (b) is sectional drawing of the width direction of a 1st tie bar. It is a top view which shows the ground-contact surface of the tread part of a 50% load application state. It is a top view which shows the ground-contact surface of the tread part of a 50% load-load inclination state.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a tire meridian cross-sectional view including a tire rotation axis in a normal state of a motorcycle tire 1 of the present embodiment. The normal state is a no-load state in which the motorcycle tire 1 is assembled on the normal rim and filled with the normal internal pressure. In this specification, unless otherwise specified, dimensions and the like of each part of the tire are values specified in a normal state.

  The “regular rim” is a rim determined for each tire in a standard system including a standard on which a tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, For ETRTO, "Measuring Rim".

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

  As shown in FIG. 1, a motorcycle tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is connected to a bead core 5 of a bead portion 4 from a tread portion 2 through a sidewall portion 3. And a tread reinforcing layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2.

  The outer surface 2a between the tread ends 2t and 2t of the tread portion 2 extends and curves in a convex arc shape outward in the tire radial direction so that a sufficient ground contact area can be obtained even during turning with a large camber angle. The developed length of the outer surface 2a between the tread ends 2t and 2t is a tread developed width TW.

  The carcass 6 is constituted by, for example, one carcass ply 6A. The carcass ply 6 </ b> A includes a main body portion 6 a that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 embedded in the bead portion 4, and a folded portion 6 b that continues to the main body portion 6 a and is folded around the bead core 5. It is out.

  The carcass ply 6A has a carcass cord arranged to be inclined with respect to the tire equator C at an angle of, for example, 75 to 90 degrees, more preferably 80 to 90 degrees. For this carcass cord, for example, an organic fiber cord such as nylon, polyester, or rayon is suitably employed. A bead apex Ba made of hard rubber is disposed between the main body portion 6a and the folded portion 6b of the carcass ply 6A.

  The tread reinforcing layer 7 includes at least one or more belt plies 7A, in which the belt cord is inclined with respect to the tire equator C at an angle of, for example, 5 to 40 degrees, in the present embodiment, in the tire radial direction. 7B. The belt cords of the belt plies 7A and 7B are overlapped so as to cross each other. As the belt cord, for example, a steel cord, aramid, rayon, or the like is suitably employed. Note that the tire 1 of the present embodiment is not limited to such a radial tire, and may be a bias tire.

  FIG. 2 is a development view of the tread portion 2. As shown in FIG. 2, in the tire 1 of the present embodiment, the tread portion 2 is provided with a plurality of main grooves 8 extending continuously in the tire circumferential direction.

  The main groove 8 of the present embodiment includes one center main groove 8A extending on the tire equator C, and a pair of shoulder main grooves 8B and 8B extending on the tread end 2t side on both sides of the center main groove 8A. It is. The pair of shoulder main grooves 8B and 8B have the same distance from the tire equator C.

  The center main groove 8A and the shoulder main groove 8B each extend linearly. Such a main groove 8 can easily drain the water in the groove from the rear arrival side in the rotational direction. The center main groove 8A and the shoulder main groove 8B are not limited to such an aspect, and may be, for example, a zigzag shape or a wave shape.

  The groove width W1 and the maximum groove depth D1 of the main groove 8 can be variously determined according to common practice. The groove width W1 of the main groove 8 is, for example, about 2% to 10% of the tread development width TW. Further, the maximum groove depth D1 (shown in FIG. 1) of the main groove 8 is, for example, about 6 to 10 mm. Further, the main groove 8 of the present embodiment has a groove bottom surface where the groove depth of the main groove 8 is maximum in the cross section in the groove width direction, and a groove wall surface extending inward in the tire radial direction from the tread surface of the tread portion 2. (Not shown). The angle between the groove bottom surface and the groove wall surface is preferably 95 to 110 degrees.

  The tread portion 2 is divided by the main groove 8 into a pair of center land portions 9 and 9 and a pair of shoulder land portions 10 and 10.

  Each center land portion 9 is provided between the center main groove 8A and the shoulder main groove 8B. The center land portion 9 of the present embodiment is not provided with a groove or siping and is configured as a rib extending continuously in the tire circumferential direction. Such a center land portion 9 has great rigidity and improves the straight running stability of the tire 1. The center land portion 9 is not limited to such a mode.

  Each shoulder land portion 10 is provided between the shoulder main groove 8B and the tread end 2t. The shoulder land portion 10 is provided with a plurality of shoulder inclined grooves 11 extending in a direction intersecting with the shoulder main groove 8B.

  The shoulder inclined groove 11 extends linearly, for example. Such shoulder inclined grooves 11 have a low drainage resistance, and thus improve drainage performance. Therefore, drainage performance and steering stability performance are improved in a well-balanced manner. The shoulder inclined groove 11 is not limited to such an aspect, and may be, for example, a zigzag shape or a wave shape.

  For example, both ends of the shoulder inclined groove 11 terminate in the shoulder land portion 10. Thereby, the rigidity of the shoulder land portion 10 is ensured to be high, and the steering stability performance is improved. The shoulder inclined groove 11 is not limited to such an aspect, and for example, an aspect in which one end communicates with the shoulder main groove 8B or an aspect in which the other end communicates with the tread end 2t may be employed. Further, the shoulder inclined groove 11 may be connected to the shoulder main groove 8B and the tread end 2t.

  Although not particularly limited, the angle θ1 of the shoulder inclined groove 11 with respect to the tire circumferential direction is, for example, about 5 to 80 degrees. The groove width W2 of the shoulder inclined groove 11 is, for example, about 2% to 10% of the tread development width TW. The maximum groove depth D2 (shown in FIG. 1) of the shoulder inclined groove 11 is, for example, about 6 to 10 mm. Furthermore, the shoulder inclined groove 11 of the present embodiment includes a groove bottom surface where the groove depth of the shoulder inclined groove 11 is maximum in the cross section in the groove width direction, and a groove wall surface extending inward in the tire radial direction from the tread portion 2 tread surface. (Not shown). The angle between the groove bottom surface and the groove wall surface is preferably 95 to 110 degrees.

  Each main groove 8 is provided with at least one first tie bar 12 having a raised groove bottom. Such a first tie bar 12 increases the rigidity of the tread portion 2 by increasing the volume of the tread portion 2 (tread rubber), and suppresses deformation of the main groove 8 that closes due to vertical load or lateral force from the road surface. . Thereby, the ground contact area of the tire 1 is sufficiently secured, and the steering stability performance of the tire 1 is improved. Further, the first tie bar 12 prevents a reduction in the groove volume of the main groove 8 due to the closing of the main groove 8. Therefore, the tire of the present invention improves drainage performance and steering stability performance in a well-balanced manner.

  The first tie bar 12 of the present embodiment includes a first center tie bar 12A provided in the center main groove 8A and a first shoulder tie bar 12B provided in each shoulder main groove 8B.

  FIG. 3A is a cross-sectional view (cross section AA in FIG. 2) along the longitudinal direction of the main groove 8 including the first tie bar 12. As shown in FIG. 3A, the first tie bar 12 of the present embodiment has a main portion 14a having a constant groove depth and a groove depth toward both outer sides in the tire circumferential direction of the main portion 14a. And a gradually increasing sub-part 14b. The sub-part 14b improves the drainage performance in order to reduce the drainage resistance of the main groove 8.

  FIG. 3B is a cross-sectional view in the width direction of the first tie bar 12 (BB cross section in FIG. 2). As shown in FIG. 3B, the first tie bar 12 of the present embodiment protrudes over the entire width of the main groove 8. In the present embodiment, the first tie bar 12 is formed with an arcuate surface in which the main portion 14a and the groove wall surface are convex toward the outside of the groove, so that the rigidity of the tread portion 2 is greatly improved.

  As shown in FIG. 2, in the present embodiment, the first tie bar 12 provided in one main groove 8 is provided at a position different from the first tie bar 12 provided in the other main groove 8 in the tire circumferential direction. It has been. Thereby, the rigidity and drainage performance of the tread portion 2 are not biased in the tire circumferential direction, and are easily made uniform. Therefore, in the tire 1 of the present embodiment, the drainage performance and the steering stability performance are further improved in a well-balanced manner.

  The first tie bars 12 are preferably provided at equal pitches. Thereby, the deformation | transformation which closes each main groove 8 is suppressed uniformly in a tire peripheral direction. In order to exhibit such an action more effectively, the first shoulder tie bar 12B of one shoulder main groove 12B and the first shoulder tie bar 12B of the other shoulder main groove 12B are positioned at equal pitches in the tire circumferential direction. It is desirable to have shifted.

  FIG. 4 shows an example of the contact surface Sa of the tread portion 2 in a 50% load-load state in which 50% of the normal load is applied to the tire 1 in the normal state and is grounded to a plane with a camber angle of 0 degrees. . The “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JAMATA” indicates “maximum load capacity”, and TRA indicates “TIRE” The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” in the case of ETRTO.

 As shown in FIG. 4, it is desirable that at least one first tie bar 12 is included in each main groove 8 in the ground contact surface Sa of the tread portion 2 in a state where a 50% load is applied. This ensures that the first tie bar 12 is included in each main groove 8 on the ground contact surface during straight traveling or initial turning. For this reason, high steering stability performance is ensured.

  If two or more first tie bars 12 are arranged in each main groove 8 on the ground contact surface of the tread portion 2 in a state where a 50% load is applied, drainage in the main groove 8 may not be performed smoothly. For this reason, the number of first tie bars 12 provided in each main groove 8 is more preferably one on the ground contact surface of the tread portion 2 in a state where a 50% load is applied. The contact surface Sa has the largest contact length on the tire equator C. Therefore, as shown in FIG. 2, in the tire 1 of the present embodiment, the pitch P2 of the first shoulder tie bar 12B provided in the shoulder main groove 8B is set to the first center tie bar 12A provided in the center main groove 8A. It is obtained by making it smaller than the pitch P1.

  As shown in FIG. 3A, the groove depth D3 of the main groove 8 at the first tie bar 12 is preferably 50% to 70% of the maximum groove depth D1 of the main groove 8. When the groove depth D3 of the main groove 8 at the first tie bar 12 is less than 50% of the maximum groove depth D1 of the main groove 8, the drainage resistance of the main groove 8 is increased, and the drainage performance may be deteriorated. When the groove depth D3 of the main groove 8 at the first tie bar 12 exceeds 70% of the maximum groove depth D1 of the main groove 8, the rigidity of the tread portion is reduced, and the steering stability performance may be deteriorated.

  The length La along the longitudinal direction of the groove of the main portion 14a of the first tie bar 12 is preferably 50% to 75% of the length Lt along the longitudinal direction of the groove of the first tie bar 12. Thereby, the rigidity of the tread portion 2 can be largely ensured while suppressing the drainage resistance of the first tie bar 12.

  From the viewpoint of effectively exhibiting the above action, the length Lt along the longitudinal direction of the groove of the first tie bar 12 is preferably 4 to 10 mm.

  As shown in FIG. 2, in the present embodiment, each shoulder inclined groove 11 is provided with at least one second tie bar 13 in which the groove bottom is raised. Thereby, while the rigidity of the shoulder land part 10 is ensured largely, the deformation | transformation which the groove volume of the shoulder inclination groove | channel 11 reduces is suppressed. Therefore, the tire 1 of the present embodiment further improves the steering stability performance and drainage performance during turning. The second tie bar 13 has, for example, the same cross-sectional shape in the longitudinal direction and the width direction as the first tie bar 12.

  FIG. 5 shows an example of the contact surface Sb of the tread portion 2 in the inclined state of 50% load load in which 50% of the normal load is applied to the tire 1 in the normal state and is grounded to the plane at a camber angle of 30 degrees. . As shown in FIG. 5, it is desirable that each shoulder inclined groove 11 includes at least one second tie bar 13 in the ground contact surface Sb of the tread portion 2 in the 50% load load inclined state. Thereby, since the second tie bar 13 is surely included in each shoulder inclined groove 11 during turning, the steering stability performance during turning is enhanced.

  If two or more second tie bars 13 are arranged in each shoulder inclined groove 11 on the ground contact surface of the tread portion 2 in a state where the load is inclined by 50%, drainage in the groove may not be performed smoothly. For this reason, the number of the second tie bars 13 provided in each shoulder inclined groove 11 is more preferably one on the ground contact surface of the tread portion 2 in the 50% load load inclined state. It should be noted that the shoulder inclined groove 11 whose length in the tire axial direction of the shoulder inclined groove 11 appearing on the ground contact surface Sb is 60% or less of the maximum width in the tire axial direction of the ground contact surface Sb is examined for the presence or absence of the second tie bar 13. Not.

  In the ground contact surface Sb of the tread portion 2 in the state where the load is inclined by 50%, the second tie bar 13 provided in one shoulder inclined groove 11 is in the tire axial direction with the second tie bar 13 provided in the other shoulder inclined groove 11. It is desirable to be provided at different positions. Thereby, the force from the road surface can be reduced with a good balance over the tire axial direction by the second tie bars 13.

  The second tie bar 13 is preferably the same size as the first tie bar 12. That is, the length (not shown) along the longitudinal direction of the groove of the main portion of the second tie bar 13 is preferably 50% to the length (not shown) of the length along the longitudinal direction of the groove of the second tie bar 13. 75%. The length along the longitudinal direction of the groove of the second tie bar 13 is preferably 4 to 10 mm. The groove depth D4 (shown in FIG. 1) of the shoulder inclined groove 11 at the second tie bar 13 is preferably 50% to 70% of the maximum groove depth D2 of the shoulder inclined groove 11. Since the second tie bar 13 supports a large lateral force, the length along the longitudinal direction of the groove of the second tie bar 13 arranged on the tread end 2t side is set to the second tie bar arranged on the tire equator C side. You may make larger than the length along the longitudinal direction of 13 groove | channels.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to said specific embodiment, It implements by changing into various aspects.

A motorcycle tire having the basic structure shown in FIG. 1 and the basic pattern shown in FIG. The main common specifications and test methods for each sample tire are as follows.
Maximum groove depth of main groove: 5.5mm
Maximum depth of shoulder sloping groove: 5.5mm
The second tie bar has the same shape as the first tie bar.

<Steering stability>
Each test tire was mounted on the rear wheel of a 1000 cc motorcycle under the following conditions. A commercial tire is mounted on the front wheel. Then, the test rider drove the test course, which is a circuit course on the dry asphalt road surface, and the running characteristics related to the steering response, rigidity, and grip force at this time were evaluated based on the test rider's sensuality. The results are displayed with a score of Comparative Example 1 being 100. The larger the value, the better.
<Front wheel>
Size: 120 / 70R17
Rims: 6.0 × 17
Internal pressure: 250 kPa
<Rear wheel>
Size: 190 / 55ZR17
Rims: 3.5 x 17
Internal pressure: 250 kPa

<Drainage performance>
A test rider drove the test vehicle on a wet asphalt road with a water depth of 6 mm, and the hydroplaning speed was measured. The results are displayed as an index with Comparative Example 1 as 100. The larger the value, the better.
Table 1 shows the test results.

  As a result of the test, it can be confirmed that the tires of the examples are improved in a balanced manner as compared with the tires of the comparative examples.

2 Tread 8 Main groove 12 First tie bar

Claims (7)

A motorcycle tire having a tread portion,
The tread portion is provided with at least two main grooves extending continuously in the tire circumferential direction,
Each of the main grooves is provided with at least one first tie bar having a raised groove bottom,
A tire for a motorcycle, wherein the first tie bar provided in one main groove is provided at a position different from the first tie bar provided in another main groove in a tire circumferential direction.   In the ground contact surface of the tread portion in the state of 50% load loading, in which the regular rim is assembled and the regular internal pressure is filled and 50% of the normal load is loaded and the camber angle is 0 degrees, the main surface The motorcycle tire according to claim 1, wherein at least one first tie bar is included in the groove. The main groove includes a pair of shoulder main grooves extending most on the tread end side,
The tread portion is further provided with a plurality of shoulder inclined grooves extending in the direction intersecting the shoulder main groove on the outer side of the shoulder main groove in the tire axial direction,
The motorcycle tire according to claim 1 or 2, wherein each shoulder inclined groove is provided with at least one second tie bar having a groove bottom raised. In the ground contact surface of the tread portion in the inclined state of 50% load load, in which the normal rim is assembled and the normal internal pressure is filled, and 50% of the normal load is loaded and grounded to the plane at a camber angle of 30 degrees,
The motorcycle tire according to claim 3, wherein each shoulder inclined groove includes at least one second tie bar. In the ground contact surface of the tread portion in the inclined state of the 50% load load,
The motorcycle tire according to claim 4, wherein the second tie bar provided in one shoulder inclined groove is provided at a position different from the second tie bar provided in another shoulder inclined groove in a tire axial direction. . The groove depth at the first tie bar of the main groove is 50% to 70% of the maximum groove depth of the main groove,
The motorcycle tire according to any one of claims 3 to 5, wherein a groove depth of the shoulder inclined groove at the second tie bar is 50% to 70% of a maximum groove depth of the shoulder inclined groove.   The motorcycle tire according to any one of claims 3 to 6, wherein the first tie bar and the second tie bar have a length of 4 to 10 mm along a longitudinal direction of the groove.

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