JP2905256B2 - High-speed pneumatic tires - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for high-speed running with an improved tread pattern for reducing tire noise.

2. Description of the Related Art Conventional pneumatic tires for high-speed running include a plurality of pneumatic tires arranged at predetermined intervals in an axial direction on an outer surface of a tread portion in order to enhance steering stability, durability, drainage, and the like during high-speed running. By forming a plurality of circumferential grooves extending in the circumferential direction, for example, three to six circumferentially extending main grooves are formed, and a plurality of circumferentially extending land portions are defined. By inclining forward in the tire rotation direction (inclination at an angle of 30 to 90 degrees with respect to the equatorial plane of the tire), and forming a plurality of lateral grooves having both ends opened in the main groove separated by a predetermined distance in the circumferential direction. , A plurality of blocks separated in the circumferential direction.

Problems to be Solved by the Invention However, such a tire has a problem that tire noise is increased and comfortability is reduced particularly when traveling at a high speed exceeding 200 km / h. The reason is that running the tire as described above,
When the front end in the rotation direction of the block steps on the road surface, it hits the road surface to generate noise. Such noise is generated every time the block is stepped on the road surface. Therefore, the noise increases as the rotation speed of the tire increases. Also, when the tire rotates and the lateral groove reaches the ground contact area, the air in the lateral groove is compressed by the deformation of the block, and when this compressed air is rapidly discharged to the outside from the opening end of the lateral groove,
Although so-called pumping noise occurs, such pumping noise has a peak at a certain frequency because the volume of the lateral groove is constant, and as a result, it is perceived as loud noise. In order to reduce such tire noise, it is only necessary to eliminate the lateral grooves and use only the ribs. However, in this case, there is a problem that the steering stability, durability, drainage, etc. at the time of high-speed running are reduced. .

An object of the present invention is to provide a pneumatic tire for high-speed running that can effectively reduce tire noise without deteriorating steering stability, durability, drainage, and the like during high-speed running.

Means for Solving the Problems Such an object is achieved by providing a plurality of circumferentially arranged circumferentially spaced apart from each other by a predetermined distance on an outer surface of a cylindrical tread portion extending over a pair of sidewall portions. A plurality of land sections extending in the circumferential direction are defined by forming a main groove extending in the direction, and each of the land sections is inclined forward in the tire rotation direction from the tread end toward the tire equatorial plane. In a pneumatic tire for high-speed running formed by separating a plurality of lateral grooves separated by a predetermined distance in the circumferential direction, at least one of the lateral grooves in the land portion row is provided with a transverse groove having both ends opened in the main groove, and a tread end close to the transverse groove. One end opening to the main groove, and the other end close to the tire equatorial plane being interrupted at the middle in the width direction of the land row, and a transverse groove is arranged on both circumferential sides of the interrupted groove. Do This can be achieved by:

Action Assume that the vehicle is running on a road surface with the tire of the present invention. At this time, the front end in the rotation direction of a part of the block-shaped land row located between two adjacent transverse grooves hits the road surface when stepping into the ground contact area, and generates noise. On the other hand, the interruption groove ends halfway in the width direction of the land row, and as a result, the land row between the other end of the interruption groove and the main groove is continuous in the circumferential direction. There is almost no noise when stepping on. Here, in the present invention,
Since at least one of the land rows is provided with an interruption groove in addition to the transverse groove, the number of hits on the road surface is reduced by the number of interruption grooves, so that noise is reduced. In addition, since the interruption groove is shorter than the transverse groove and has a smaller volume, the frequency of the pumping noise is different from the pumping noise generated in the transverse groove, and as a result, it is felt that the noise becomes white noise and the noise is reduced. Further, noise is further reduced because the amount of air released by pumping is also reduced. In addition, there is no change in the number of horizontal grooves in each land row, so steering stability, durability,
Drainage property is maintained as it is. However, if a plurality of interruption grooves are continuously arranged in the circumferential direction, the land row will be continuous in the circumferential direction over a long distance. Changes in the circumferential direction, and uneven wear easily occurs. For this reason, in this invention, by always arranging the transverse groove on both sides in the circumferential direction of the interruption groove,
The maximum circumferential length in which the land portion rows are continuous is suppressed to two pitches or less of the lateral grooves, thereby preventing heat generation and uneven wear.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

1 and 2, reference numeral 1 denotes a tire pneumatic tire used for high-speed running. In this embodiment, the size is 255 / 40ZR17.
The tire 1 has a pair of bead portions 2,
It has a pair of sidewall portions 3 extending radially outward from the bead portions 2, respectively, and a cylindrical tread portion 4 extending between both sidewall portions 3. The tire 1 is reinforced with a toroidal carcass layer 8 extending from one bead portion 2 to the other bead portion 2. Both sides of the carcass layer 8 are formed of a bead ring 9 and a rubber filler 10. It is wound around from the inside in the axial direction to the outside in the axial direction. The carcass layer 8 is composed of at least one carcass ply. In the carcass ply, a large number of cords that extend substantially in the radial direction, that is, embed a plurality of cords that cross the tire equatorial plane S at substantially 90 degrees are embedded. A belt layer 14 is provided on the tread portion 4 on the radially outer side of the carcass layer 8, and the belt layer 4 is formed by laminating at least two belt plies having a non-extensible cord embedded therein. . The cords buried in these belt plies are inclined so as to intersect with the tire equatorial plane S at an angle of 15 to 35 degrees, and the belt plies are inclined and crossed in opposite directions to each other. . Reference numeral 16 denotes a reinforcing layer that covers at least both ends in the axial direction of the belt layer 14. The reinforcing layer 16 is composed of at least one reinforcing ply having a cord embedded therein. Are arranged substantially in equilibrium.
A tread rubber 18 having a cylindrical shape is disposed on the tread portion 4 on the radially outer side of the belt layer 14 and the reinforcing layer 16.

On the outer surface of the tread rubber 18, a plurality of parallel main grooves 20 which are arranged at predetermined intervals in the rotation axis direction of the tire 1, in this embodiment, four wide main grooves 20, are formed. Is preferably in the range of 3 to 10% of the tread width W, and more preferably in the range of 5 to 8%. In this embodiment, the width of the main groove 20 is 10 mm and the depth is 8 mm. And
These main grooves 20 extend in a circumferential direction substantially parallel to the tire equatorial plane S, and have a linear shape. As a result, these main grooves 20
Between the main groove 20 and the tread ends 22, a plurality of, in this embodiment, five land rows 24 extending continuously in the circumferential direction.
Is defined. The outer land rows 24a, 24e closest to the tread end 22 and the middle land rows 24c provided on the tire equatorial plane S and the intermediate land rows 24a, 24e are arranged between the outer land rows 24a, 24e. A plurality of lateral grooves 25a, 25e and 25b, 25d are formed in the land rows 24b, 24d, respectively. These lateral grooves 25a, 25e, 25b, 25d are spaced apart from each other by a predetermined distance in the circumferential direction. In this embodiment, in order to reduce noise more effectively, the distance (pitch) between the adjacent lateral grooves 25 is set.
Is changed in the circumferential direction, that is, a pitch variation is applied. Also, a lateral groove arranged on one side of the tire equatorial plane S
Transverse grooves arranged on the other side of 25a, 25b and tire equatorial plane S
25d and 25e are displaced by approximately 1/2 of the pitch, and in this embodiment by 15 mm in the circumferential direction. In addition, these lateral grooves 25a, 2
5e, 25b and 25d are inclined forward in the rotation direction of the tire 1 from the tread end 22 toward the tire equatorial plane S. Here, the tire equatorial plane S in the lateral grooves 25a and 25e
The inclination angle with respect to the tire equatorial plane S at each position of the lateral grooves 25b and 25d becomes smaller as approaching the tire equatorial plane S. The horizontal groove 25a and the horizontal groove 25e and the horizontal grooves 25b and 25d closest to each other extend along substantially the same curve from the viewpoint of improving drainage. The lateral grooves 25b, 25d in at least one of the land rows 24, in this embodiment, the intermediate land rows 24b, 24d,
The main groove 20 extends over the entire width of the middle land row 24b, 24d
a, 20b, 20c, 20d, respectively, a transverse groove 26, which opens at a part of the width of the intermediate land row 24b, 24d, and the tread edge 22
, While the other end 28 close to the tire equatorial plane S has an interrupting groove 29 ending in the middle of the intermediate land rows 24b, 24d in the width direction. It is composed of Thus, the cross-groove on the land rows 24b, 24d
Since the interruption groove 29 is provided in addition to 26, the noise can be effectively reduced without deteriorating the steering stability, durability, drainage, and the like during high-speed running. Note that, as in this embodiment, the land rows provided with the transverse grooves 26 and the interruption grooves 29 are the intermediate land rows 24b and 24d of the land rows 24 because the contribution rate to noise is outside land. Intermediate land row 24b, 2 from row 24a, 24e
4d is high and the outer land rows 24a, 24e
If the transverse groove 26 and the interruption groove 20 are provided as described above, the rigidity of the land portion becomes uneven in the circumferential direction, and the steering stability decreases. Here, if a plurality of the interrupting grooves 29 are arranged continuously in the circumferential direction, the land portion rows 24 will be continuous in the circumferential direction over a long distance, so that heat is generated during high-speed running and durability is reduced. At the same time, the rigidity changes in the circumferential direction and uneven wear easily occurs. For this reason, in this embodiment,
By arranging the transverse groove 26 and the interrupting groove 29 in 24b, 24d such that the transverse groove 26 is always located on both circumferential sides of the interrupting groove 29, the maximum circumferential length in which the land part row 24 is continuous is determined by the transverse groove.
Twenty-five times less than the pitch of 25 to prevent heat generation and uneven wear. Here, in order to efficiently balance drainage and noise reduction, one interruption groove 29 and a plurality of crossing grooves are used.
26 are alternately arranged in the circumferential direction. In this embodiment, two transverse grooves 26 of one interruption groove 29 are alternately arranged. Further, the other end 28 of the interruption groove 29 is located at the center in the width direction of the intermediate land portion rows 24b and 24d in which the interruption groove 29 is formed, and on the side close to the tire equatorial plane S of the intermediate land portion rows 24b and 24d. It is preferable from the viewpoint that the drainage is maintained and the noise is effectively reduced, and the intermediate land portion rows 24b and 24d extend from the side wall close to the tire equatorial plane S to the intermediate land portion. More preferably, it ends near a point separated by 1/3 of the width of the rows 24b, 24d. In this embodiment, the processing ends at a point separated by 1/4 of the width of the intermediate land rows 24b and 24d. As shown in FIGS. 2 and 3, at the end of the transverse groove 26 close to the tire equatorial plane S, a blot foam portion 30 is formed which protrudes radially outward from the bottom surface thereof. 26 is the platform 30
And a shallow groove portion 31 having a shallow groove depth, and a deep groove portion 32 having a constant depth. In this manner, if the shallow groove 31 is provided at the end of each transverse groove 26 near the tire equatorial plane S,
The intermediate land portion rows 24b, 24d can be provided with continuity in the circumferential direction, though incomplete, through the platform portion 30 without lowering the drainage performance, thereby making it possible to somewhat reduce tire noise. Here, setting the groove depth H in the shallow groove portion 31 to be in the range of 20 to 80% of the groove depth J in the deep groove portion 32 effectively has the circumferential continuity without lowering drainage. It is preferable from the point of making. Further, the shallow groove portion 31 is disposed between the opening end of the transverse groove 26 on the side close to the tire equatorial plane S and the center in the width direction of the intermediate land portion rows 24b and 24d, so that drainage and noise reduction are achieved. This is preferable from the viewpoint of efficiently achieving both. In this embodiment, the depth H of the shallow groove portion 31 is 3 mm, while the depth J of the deep groove portion 32 is 7 mm, and the shallow groove portion 31 extends from the opening end to the middle land row 24b, 24d.
Extends to a point 1/3 of the width of The intersection angle A between the straight line L connecting the width centers of the grooves at both ends of the transverse groove 26 and the tire equatorial plane S is a straight line connecting the width centers of the grooves at one end 27 and the other end 28 of the interruption groove 29. Preferably, it is larger than the intersection angle B between M and the tire equatorial plane S.
The reason is that the transverse groove 26 divides the intermediate land row 24b, 24d, so that the rigidity of the intermediate land row 24b, 24d is lower in the vicinity of the transverse groove 26 than in the vicinity of the interruption groove 29, and as a result, Although uneven wear easily occurs, the rigidity in the vicinity of the transverse groove 26 is increased in the manner described above, so that the rigidity of the intermediate land rows 24b and 24d becomes uniform in the circumferential direction, and uneven wear is prevented. . In this embodiment, the intersection angle A is 60
And B is 55 degrees. On the other hand, no lateral groove is formed in the central land portion row 24c arranged on the remaining tire equatorial plane S, and as a result, the central land portion row 24c is continuously divided without being divided in the circumferential direction. I have. Also, all lateral grooves 25a, 25e provided in the outer land rows 24a, 24e have both ends on the outer land rows 24a, 2e.
4e, a groove opening at the side wall of the tread edge 22 and opening at the side wall of the tread end 22. The groove width Q at the open end of the lateral grooves 25a, 25e near the tire equatorial plane S. Wider than R. In this embodiment, the groove width Q is 8 mm and R is 4 mm. Further, in this embodiment, in order to improve the drainage of water flowing in the circumferential direction and further improve the uneven wear resistance, the main groove is used.
As shown in FIGS. 4 (a) and 4 (b), the inclination angles G of the side walls of the tires 20a and 20d close to the tire equatorial plane S with respect to the radial direction are shown in FIGS.
Between the lateral grooves 25b, 25d adjacent in the circumferential direction, gradually increase toward the rear in the rotation direction of the tire, whereby
The cross-sectional area of the main grooves 20a and 20d is increased intermittently in the circumferential direction. The angle F is the intersection angle between the extension of the opening edge of the main grooves 20a and 20d close to the tire equatorial plane S and the straight line parallel to the tire equatorial plane S, and is 5 degrees in this embodiment.

FIG. 5 is a view showing a second embodiment of the present invention. In this embodiment, the outer surface of the tread portion 4 has six main grooves.
35, and among the land rows 36 defined by these main grooves 35, the outer land rows 36a and 36g and the central land row 36d
Transverse ditch in four intermediate land rows 36b, 36c, 36e, 36f between
37 and the interruption groove 38 are arranged in the same manner as described above. Here, the lateral groove of the intermediate land part row 36c that is closest to the interruption groove 38 of the intermediate land part row 36b is always the transverse groove 37, and is also the closest to the interruption groove 38 of the intermediate land part row 36c. The transverse groove of the middle land row 36b is always the transverse groove 37. This means that
The same applies between e and 36f. This is tire 1
This is to prevent a decrease in drainage during traveling.
In this embodiment, the same shallow groove portion 40 as described above is provided at the end of the lateral groove 39 formed on the outer land portion rows 36a and 36g near the tire equatorial plane S.

Next, test examples will be described. In this test, the test tire having a tread pattern as shown in FIGS.
A comparative tire having a constant depth at any position and having lateral grooves opened at both ends in the main groove was prepared.

Next, while each tire is filled with an internal pressure of 2.5 kg, a load of 500 kg is applied, and the tire is initially run on a 2.0 m diameter drum at a speed of 200 kg / h.
After increasing the speed by m, the tire was allowed to run until a failure occurred, and the speed at the time of occurrence of the failure was set as an index of 100 to determine high-speed durability. The results show that both the conventional tire and the test tire were 100, and there was no decrease in high-speed durability. Here, the index 100 was actually 300 km / h. For each tire
After filling the internal pressure of 2.5 kg, it was mounted on a test car, and was driven on a circuit to determine the steering stability of each tire from the lap time and the driver's feeling. The results are shown in exponential notation.
And there was no decrease in steering stability. Furthermore, after filling each tire with 2.5 kg of internal pressure, it is mounted on a test car, a pool with a depth of 10 mm is provided on a turning course with a radius of 100 m, and enters the pool while running at 70 km / h. The change in G was measured to determine drainage.
The results are shown in exponential notation.
And there was no decrease in drainage. Where the index 100 is
0.4G. Furthermore, after filling each tire with 2.5 kg of internal pressure, it is mounted on a test car and turned on a dry road surface 10 times at a speed of 70 km / h while drawing a circle with a radius of 50 m, and the wear of the parts with the most wear and the parts with the least wear The uneven wear resistance was determined from the amount. When the result was shown by an index, it was 100 in the conventional tire, but was 80 in the test tire, and the uneven wear resistance was improved. After each tire was filled with 2.5 kg of internal pressure, it was mounted on a test car, and the pattern noise was measured while coasting on a smooth road surface at 80 km / h. When the result was shown by an index, it was 100 in the test tire, but was 85 in the test tire, and the noise was sufficiently reduced.
Here, the index 100 was actually 55 dB.

In the above-described embodiment, the main groove 20 and the lateral groove 25 are provided substantially symmetrically with respect to the tire equatorial plane S. However, in the present invention, they may be arranged asymmetrically with respect to the tire equatorial plane S.

Effects of the Invention As described above, according to the present invention, tire noise can be effectively reduced without lowering steering stability, durability, drainage, and the like during high-speed running.

[Brief description of the drawings]

FIG. 1 is a meridian sectional view showing a first embodiment of the present invention, FIG. 2 is a developed view of a tread portion, FIG. 3 is a sectional view taken along the line II of FIG. 2, and FIG. ) Is a sectional view taken along the line II-II of FIG. 2, FIG. 4 (b) is a sectional view taken along the line III-III of FIG. 2, and FIG. 5 is a development of a tread portion showing a second embodiment of the present invention. FIG. 3 ... sidewall portion 4 ... tread portion, 20 ... main groove 22 ... tread edge, 24 ... land row 25 ... lateral groove, 26 ... transverse groove 27 ... one end, 28 ... other end 29 …… Suspend groove, S …… Equatorial plane of tire

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-147412 (JP, A) JP-A-3-96408 (JP, A) JP-A-61-200006 (JP, A) JP-A-2- 102802 (JP, A) JP-A-2-151508 (JP, A) JP-A-2-175304 (JP, A) JP-A-55-91407 (JP, A) JP-A-2-270609 (JP, A) Japanese Utility Model Showa 57-182503 (JP, U) Japanese Utility Model Showa 62-49402 (JP, U) Japanese Utility Model Showa 60-18003 (JP, U) Japanese Utility Model Showa 3-40002 (JP, U) (58) Fields surveyed (Int.Cl. ⁶ , DB name) B60C 11/04 B60C 11/06 B60C 11/11

Claims (1)

(57) [Claims] 1. A plurality of circumferentially extending main grooves arranged at predetermined intervals in an axial direction are formed on an outer surface of a cylindrical tread portion extending over a pair of sidewall portions. In this way, a plurality of land rows extending in the circumferential direction are defined, and a plurality of lateral grooves inclined forward in the tire rotation direction from the tread end toward the tire equatorial plane are defined in these land rows in the circumferential direction. In a pneumatic tire for high-speed running formed in isolation, a lateral groove in at least one land portion row is formed by a transverse groove having both ends opened in the main groove, and a lateral groove having one end close to the tread end being opened in the main groove. An interrupting groove whose other end close to the tire equatorial plane ends in the width direction of the land row, and a transverse groove is arranged on both circumferential sides of the interrupting groove. High speed running Use pneumatic tire.