WO2014167769A1

WO2014167769A1 - Pneumatic tire

Info

Publication number: WO2014167769A1
Application number: PCT/JP2014/001064
Authority: WO
Inventors: 慶一加藤
Original assignee: 株式会社ブリヂストン
Priority date: 2013-04-12
Filing date: 2014-02-27
Publication date: 2014-10-16
Also published as: JP2014205416A; CN105121184B; JP6068239B2; CN105121184A

Abstract

Provided is a pneumatic tire in which road noise is reduced and drainage is improved. The pneumatic tire is characterized in that buttress parts (10) are provided in areas that constitute half of the areas from the tread-ground-contact ends (TE) of the pneumatic tire to the tire maximum-width positions, and that are located toward the ground-contact ends; at least one buttress peripheral groove (12) extending continuously in the peripheral direction of the tire is formed in at least one buttress part (10); the buttress peripheral groove (12) has wide parts (14) having a predetermined groove width and narrow parts (16) smaller in groove width than the wide parts (14); and the wide parts (14) and narrow parts (16) are disposed repeating alternately along the direction of extension of the buttress peripheral groove (12).

Description

Pneumatic tire

The present invention relates to a pneumatic tire.

Conventionally, a tire mounted on a vehicle such as a passenger car has a problem of road noise generated when the tire rolls on a road surface having irregular irregularities, such as a rough paved road. In order to reduce this road noise, for example, it is known that a plurality of recesses are formed along the tire circumferential direction in the buttress region of the tread to reduce road noise due to vibration of the buttress portion ( For example, see Patent Document 1).

JP 2011-68334 A

By the way, it is assumed that the tire not only rolls on a dry road surface but also rolls on a wet road surface in rainy weather. Therefore, drainage is one of the important factors in the performance of the tire, and higher drainage is also demanded for the tire as described above.

Therefore, an object of the present invention is to provide a pneumatic tire that reduces road noise and improves drainage.

The present invention has been made to solve the above problems, and in the pneumatic tire according to the present invention, a buttress circumferential groove extending continuously in the tire circumferential direction is formed in at least one buttress portion, The groove has a wide part having a predetermined groove width and a narrow part having a groove width smaller than the wide part, and the wide part and the narrow part are alternately arranged along the extending direction of the buttress circumferential groove. It is characterized by being arranged repeatedly.

According to the present invention, it is possible to provide a pneumatic tire with reduced road noise and improved drainage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial development view of a tread surface and a region on both outer sides in a tire width direction of a pneumatic tire according to an embodiment of the present invention. (A) is a diagram showing only one buttress circumferential groove of the pneumatic tire of FIG. 1, (b) is an enlarged view of the AA cross section of FIG. 2 (a), (c) FIG. 3 is an enlarged view of the BB cross section of FIG.

Hereinafter, the pneumatic tire of this embodiment (hereinafter, also simply referred to as a tire) will be described in detail with reference to the drawings. FIG. 1 is a developed view of a tread surface of a tire according to the present invention and regions on both outer sides in the tire width direction. In addition, about the internal structure of tires, such as a carcass and a belt, since it is the same as that of the past, description is abbreviate | omitted.
The “tread grounding end” refers to the grounding end in the tire width direction of the tire when the tire is mounted on the applicable rim, filled with the specified internal pressure, and the maximum load load is applied (hereinafter also referred to as “predetermined state”). Point to. In addition, the “buttress portion” refers to a region on the ground contact end side half portion in a predetermined state in a tire width direction cross-sectional view from a tread ground contact end in the tire width direction to a tire maximum width position in a predetermined state. “Applicable rim” is an industrial standard effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK is used. In Europe, ETRTO (European Tire and Rim Technical Organization) is used. STANDARD MANUAL, in the United States, refers to a rim defined by TRA (THE TIRE and RIM ASSOCATION INC.) YEAR BOOK, etc. In addition, “specified internal pressure” means a state in which a tire is mounted on an applicable rim, and an internal pressure (maximum air pressure) corresponding to a tire maximum load capacity of a standard tire such as JATMA is applied. Means a load corresponding to the maximum load capacity. The “groove width” of each groove is the opening width of the outer surface of the tire in a cross section perpendicular to the extending direction of each groove when the tire is mounted on the applicable rim, the specified internal pressure is filled, and no load is applied. It shall be said. Further, the “tread surface” refers to a tire width direction region sandwiched between the tread contact ends on both sides of the outer surface of the tire. In addition, “the angle of the groove side wall with respect to the normal standing on the outer surface of the buttress portion at the opening edge of the buttress circumferential groove to the outer surface of the buttress portion” refers to the outer surface of the buttress portion when the groove side wall is a curved surface. Refers to the angle of the tangent at the opening edge to the normal.

As shown in FIG. 1, the tire has a single wide main groove 2 that extends continuously in the tire circumferential direction on the tread surface 1. In addition, this tire has one circumferential main groove 3 having a groove width smaller than the groove width of the wide main groove 2 in the other half of the tread tread surface 1 in the tire width direction centered on the tire equatorial plane CL. Have only. Further, as shown in FIG. 1, the

land portions

4 a and 4 b adjacent to both sides in the tire width direction of the wide main groove 2 are rib-like land portions that are continuous in the tire circumferential direction, and the tire width direction of the circumferential main groove 3. The land portion 4c adjacent to the outside is also a rib-like land portion that is continuous in the tire circumferential direction.

In addition, as shown in FIG. 1, this tire has four buttress circumferences extending linearly continuously in the tire circumferential direction on one side of the buttress portion 10 located on the outer side in the tire width direction from the tread ground end TE. A groove 12 is formed. Each buttress circumferential groove 12 has a wide width portion 14 having a predetermined groove width and a narrow width portion 16 having a groove width W smaller than the wide width portion 14, and extends along the extending direction of the buttress circumferential groove 12. The wide portions 14 and the narrow portions 16 are alternately and repeatedly arranged. That is, the groove width W of the buttress circumferential groove 12 has a shape that repeats expansion and reduction along the extending direction. In this example, in the buttress circumferential groove 12, wide portions 14 and narrow portions 16 are alternately and repeatedly arranged at a constant pitch P in the tire circumferential direction. In this example, the two adjacent buttress circumferential grooves 12 are arranged in the tire circumferential direction so as to be shifted by a half of the pitch P, and the wide portion 14 of one buttress circumferential groove 12 and the other buttress circumferential groove 12 are arranged. Twelve narrow portions 16 are arranged adjacent to each other in the tire width direction. The at least one buttress circumferential groove 12 may be formed in at least one buttress portion 10, and the position and number of the buttress circumferential grooves 12 are not particularly limited. Further, the buttress circumferential groove 12 may be arranged linearly in the tire circumferential direction, or may be arranged so as to zigzag or meander.

2 (a) is an enlarged view of only one buttress circumferential groove 12 in the tire of FIG. 1, and FIGS. 2 (b) and (c) show the buttress circumferential groove 12 in FIG. 2 (a). A vertical section, AA section, and BB section are shown. The AA cross section is one cross section in the narrow portion 16, and the BB cross section is one cross section in the wide portion 14. Although the shape of the groove side walls 12a on both sides constituting the buttress circumferential groove 12 is not particularly limited, in this example, as shown in FIGS. 2B and 2C, the extending direction of the buttress circumferential groove 12 In a cross-sectional view perpendicular to the (tire circumferential direction), the contour line of the groove side wall 12a extends linearly. Further, in this example, as shown in FIGS. 2B and 2C, the opening edge 20 to the buttress portion outer surface of the buttress circumferential groove 12 with respect to the normal L standing on the buttress portion outer surface. The angle α of the groove side wall 12 a is larger in the wide portion 14 than in the narrow portion 16. Further, in the buttress circumferential groove 12, the depth d of the groove bottom 18 may be constant in the tire circumferential direction or may vary in the tire circumferential direction. In this example, the opening edge 20 of the buttress circumferential groove 12 to the outer surface of the buttress portion 10 is formed by a smooth curve in the tire circumferential direction, and extends meanderingly. In this example, the groove side wall 12a extends while smoothly curving in the tire circumferential direction, and the angles α and β also change smoothly and continuously in the tire circumferential direction.

Here, as shown in FIG. 1, a groove portion 2a is further provided at the groove bottom of the wide main groove 2, and the groove depth is deep at the portion where the groove portion 2a is provided. That is, the wide main groove 2 includes a shallow bottom portion having a shallow groove depth and a deep bottom portion having a groove depth provided with the groove portion 2a. Further, as shown in FIG. 1, the groove 2a is formed in a substantially S shape, and the inclination angle with respect to the tire circumferential direction is small at the center in the extending direction of the groove 2a, while the groove 2a. The inclination angle with respect to the tire circumferential direction is large at both ends in the extending direction. Moreover, the groove width of the groove part 2a is gradually reduced from the extending direction center side toward both end sides.

Furthermore, each

land part

4a, 4b, 4c is provided with a plurality of sipes 5 in order to secure edge components and improve grip performance. Here, the land portion 4a adjacent to the outer side in the tire width direction of the wide main groove 2 includes a plain rib portion 4d in which grooves and sipes are not disposed at least partially in the tire width direction. These are disposed at positions adjacent to the wide main groove 2. In the illustrated example, a plurality of sipes 5 extending in the tire width direction are arranged at equal intervals in the tire circumferential direction in a region outside the plain rib portion 4d in the tire width direction. A sipe 5 extending in the tire circumferential direction is also arranged so as to connect the ends. On the other hand, in the land portion 4c adjacent to the outer side in the tire width direction of the circumferential main groove 3, a plurality of sipes 5 communicating with the circumferential main groove 3 and extending inward in the tire width direction are equally spaced in the tire circumferential direction. And one sipe 5 extending in the circumferential direction of the tire is provided so as to cross it. Further, between the sipes 5 arranged at equal intervals in the tire circumferential direction, the tire extends inward in the tire width direction from the tread grounding end TE (in practice, from the outer region in the width direction) and ends in the land portion 4c. A plurality of sipes 5 are arranged at equal intervals in the tire circumferential direction.

Further, the central land portion 4b located on the center side in the tire width direction has a narrow groove portion 6a communicating with the circumferential main groove 3, and is connected to the narrow groove portion 6a and ends in the central land portion 4b, and the volume is narrow groove portion. So-called Helmholtz resonators 6 having air chamber portions 6b larger than 6a are arranged at equal intervals in the tire circumferential direction. Further, the sipe 5 communicates with an end portion of the air chamber portion 6b opposite to the narrow groove portion 6a. In the example shown in FIG. 1, the Helmholtz resonator 6 does not straddle the tire equatorial plane CL. Here, the narrow groove portion 6a refers to a portion of the Helmholtz resonator 6 having a groove width of 1 mm or less.

Hereinafter, the function and effect of this embodiment will be described. Generally, when running on a smooth road surface, the buttress portion does not come into contact with the ground, but it comes into contact when there are fine irregularities such as a paved road with a rough road surface. In the tire of the present embodiment shown in FIG. 1, the buttress circumferential groove 12 formed in the buttress portion 10 makes it difficult for the unevenness of the road surface to contact the outer surface of the buttress portion 10, so that vibration of the buttress portion 10 is suppressed. As a result, the generation of road noise due to the vibration of the buttress portion 10 can be reduced.

Moreover, the tire according to the present embodiment has the buttress circumferential groove 12 continuously extending in the tire circumferential direction in the buttress portion 10, and thus can exhibit higher drainage than the intermittent groove. Further, the buttress circumferential groove 12 has the wide portions 14 and the narrow portions 16 that are alternately and repeatedly arranged, so that the drainage capacity in the buttress portion 10 is improved. That is, the water flowing in the buttress circumferential groove 12 passes through the wide portion and then flows along the groove side wall 12a from the wide portion 14 toward the narrow portion 16 as the groove width W of the buttress circumferential groove 12 decreases. It drains in the direction of the extension line. That is, the water flowing in the buttress circumferential groove pulsates at a predetermined cycle, and is drained from the wide width portion 14 toward the narrow width portion 16 in the direction of the streamline along the groove side wall 12a. Therefore, it becomes easy to drain the water that has entered between the road surface and the tread surface, and the drainage performance is improved.

Further, since the buttress circumferential groove 12 has a continuous shape in the tire circumferential direction, the rigidity of the buttress portion 10 around the buttress circumferential groove 12 may decrease, but the tire of the present invention has the narrow portion 16. By having it, the rigidity of the buttress part 10 can be ensured and the fall of steering stability can also be suppressed. In general, the inner side of the vehicle mounting is less rigid than the outer side of the vehicle mounting due to the absence of a disk, and tire vibration is likely to occur. Therefore, the buttress portion 10 on one side where the buttress circumferential groove 12 is formed is mounted on the vehicle. The effect of reducing road noise is further improved by mounting the vehicle inside.

Here, in the tire according to the present invention, as shown in FIG. 1, in an opening edge 20 to the outer surface of the buttress portion of the buttress circumferential groove 12 in a cross-sectional view perpendicular to the extending direction of the buttress circumferential groove 12. It is preferable that the angle of the groove side wall 12a with respect to the normal L standing on the outer surface of the buttress portion is larger at the wide portion than at the narrow portion. According to this, by suppressing the rigidity reduction of the buttress part 10 in the vicinity of the wide part 14, the steering stability can be maintained at a high level, and the road noise reduction effect can be improved more reliably. Further, it is possible to reduce the difference in rigidity along the extending direction of the buttress circumferential groove 12 (that is, the tire circumferential direction), and to further suppress a decrease in steering stability.

In the tire of the present invention, as described above, two or more buttress circumferential grooves 12 are formed in at least one buttress portion 10, and two buttress circumferential grooves 12 adjacent to each other are formed in one buttress. The wide portion 14 of the circumferential groove 12 and the narrow portion 16 of the other buttress circumferential groove 12 are preferably adjacent to each other in the tire width direction. According to this, the rigidity difference in the tire circumferential direction as the entire buttress portion 10 is reduced by the wide width portion 14 that tends to be low in rigidity and the narrow width portion 16 that is easy to ensure rigidity in the tire width direction. Further, it is possible to further suppress a decrease in steering stability. Similarly, since the difference in the groove width, that is, the groove volume in the tire circumferential direction is reduced, the difference in the tire circumferential direction of the drainage effect is reduced, and the drainage can be further improved.

Further, in the tire of the present invention, it is preferable that the buttress circumferential groove 12 is formed at least in the buttress portion 10 which is on the inner side of the vehicle. According to this, since the buttress circumferential groove 12 is disposed on the inner side of the vehicle, which is less rigid than the outer side of the vehicle and less likely to cause tire vibration, the road noise reduction effect can be further improved. it can.

Furthermore, in the tire of the present invention, it is preferable that the opening edge 20 of the buttress circumferential groove 12 to the outer surface of the buttress portion 10 is formed by a smooth curve in the tire circumferential direction. According to this, the movement of the water along the groove side wall 12a in the buttress circumferential groove 12 can be made smoother, and the drainage can be improved. Further, it is possible to prevent the occurrence of a rigid step in the tire circumferential direction, and to suppress a decrease in steering stability.

In addition, in the tire of the present invention, it is preferable that the minimum groove width in the narrow portion 16 is not more than half of the maximum groove width in the wide portion 14. According to this, the drainage effect to the extension line direction of the streamline along the groove side wall 12a which goes to the narrow part 16 from the wide part 14 can be improved, and drainage can be improved more.

As the number of buttress circumferential grooves 12 in the buttress portion 10 increases, the road noise reduction effect and drainage performance are improved. However, the rigidity may be lowered accordingly, and therefore the number of buttress circumferential grooves 12 is less than the buttress portion. It is preferable to set as appropriate as long as the rigidity of 10 can be secured.

In order to confirm the effect of the present invention, the tires according to the invention example and the comparative example were made as prototypes, and the following tests for evaluating the tire performance were performed. The tire according to the invention example has the tread pattern shown in FIG. 1, and the comparative example is common to the invention example except that the buttress circumferential groove is not formed. In the following tests, the tire of the invention example was attached to the vehicle so that one side having the buttress circumferential groove was on the inside of the vehicle, and the tire of the comparative example was also attached in the direction corresponding to the invention example.

Each of the above tires having a tire size of 205 / 55R16 was mounted on an applicable rim, filled with a specified internal pressure, and the following tests were performed.
<Road noise performance>
The sound pressure level of road noise when running on an indoor drum tester at a speed of 60 km / h with a maximum load of JATMA normal internal pressure was evaluated. The evaluation result of the tire according to the comparative example is evaluated as a relative value when the tire is 100, and a larger numerical value indicates that the road noise reduction effect is greater and the road noise performance is superior.
<Drainage>
About each said tire, the driving | running | working performance at the time of drive | working on the wet road surface was evaluated by the sensory sense by a driver. The evaluation result of the tire according to the comparative example is evaluated as a relative value when the tire is set to 100, and a larger numerical value indicates better drainage.
<Steering stability>
About each said tire, the driving | running | working performance at the time of drive | working on the dry road surface was evaluated by the sensory sense by a driver. The evaluation result of the tire according to the comparative example is evaluated as a relative value when the tire is set to 100, and a larger numerical value indicates better steering stability.
The above evaluation results are shown in Table 1 below.

As shown in Table 1, it can be seen that the tire of the invention example has improved road noise performance and drainage performance while ensuring the same steering stability as the tire of the comparative example.

Thus, according to the present invention, it is possible to provide a pneumatic tire with reduced road noise and improved drainage.

1: tread surface, 2: wide main groove, 2a: groove, 3: circumferential main groove,
4a: land part, 4b: central land part, 4c: land part, 4d: plain rib part,
5: Sipe, 6: Helmholtz type resonator, 6a: narrow groove part, 6b: air chamber part,
10: Buttress part, 12: Buttress circumferential groove, 14: Wide part,
16: narrow portion, 18: groove bottom, 20: opening edge

Claims

The pneumatic tire is mounted on the applicable rim, filled with the specified internal pressure, and within the region from the tread grounding edge in the tire width direction to the tire maximum width position when the maximum load is applied, on the grounding edge side With a buttress part that exists in the area of the half,
At least one buttress circumferential groove extending continuously in the tire circumferential direction is formed in the buttress portion on at least one side,
The buttress circumferential groove has a wide portion having a predetermined groove width, and a narrow portion having a groove width smaller than the wide portion,
A pneumatic tire, wherein the wide portion and the narrow portion are alternately and repeatedly arranged along the extending direction of the buttress circumferential groove.
In a cross-sectional view perpendicular to the extending direction of the buttress circumferential groove,
The angle of the groove side wall with respect to the normal line standing on the outer surface of the buttress part at the opening edge to the outer surface of the buttress part of the buttress circumferential groove is larger in the wide part than in the narrow part. Pneumatic tire described in 2.
Two or more buttress circumferential grooves are formed on the buttress portion on at least one side,
Two buttress circumferential grooves adjacent to each other,
The pneumatic tire according to claim 1 or 2, wherein the wide portion of one buttress circumferential groove and the narrow portion of the other buttress circumferential groove are arranged adjacent to each other in the tire width direction.
The pneumatic tire according to any one of claims 1 to 3, wherein the buttress circumferential groove is formed at least in the buttress portion on the vehicle mounting inner side.
The pneumatic tire according to any one of claims 1 to 4, wherein an opening edge of the buttress circumferential groove to the outer surface of the buttress portion is formed by a smooth curve in the tire circumferential direction.
The pneumatic tire according to any one of claims 1 to 5, wherein a minimum groove width in the narrow portion is not more than half of a maximum groove width in the wide portion.