JP2007182147A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire improving high speed durability, while making steering stability and water drain property compatible. <P>SOLUTION: This tire is mounted on a vehicle imparted with a negative camber by designating the mounting direction. In the tire, a center land part 21 held by two right and left peripheral direction grooves 11 and 12 is formed in a center region of a tread surface, a block-shaped land part 22 is formed at the inside end part, and a rib-shaped land part 23 is formed at the outside end part. Block rows 24 and 25 are formed in shoulders at the inside and outside. In this case, the inside peripheral direction groove 11 of two right and left peripheral direction grooves 11 and 12 is arranged to overlap with a region where a tire peripheral direction grounding length becomes maximum when grounding the groove 11 in a mounted state on the vehicle, first inclined sub-grooves 14 extended from the inside peripheral direction groove 11 up to the midway of the center land part 21 are intermittently arranged in the tire peripheral direction, and a second inclined sub-groove 15 which intersects three or more first inclined sub-grooves 14 adjacent to each other and is not communicated with both of the two peripheral direction grooves 11 and 12 is arranged to form the block-shaped land part 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved high-speed durability when mounted on a vehicle body provided with a negative camber.

  In recent years, with improvement in performance of vehicles, improvement in high-speed running performance is also demanded for pneumatic tires. In particular, there is a demand for excellent high-speed traveling performance when traveling on both dry and wet road surfaces.

  In general, when traveling on a dry road surface at high speed, in order to increase gripping force and steering stability, the pneumatic tire is flattened or the tread portion is made a slick-based tread pattern to increase the tread rigidity. However, when such a tire travels on a wet road at a high speed, the drainage performance deteriorates and the hydroplaning resistance is significantly reduced.

  As described above, the drainage performance on the wet road surface, the grip force on the dry road surface, and the steering stability are in a trade-off relationship. For this reason, as a measure for improving the drainage performance on wet road surfaces, it has been attempted to define a plurality of wide circumferential grooves in the tread portion asymmetrically with respect to the equator and to specify the inside and outside directions when attached to the vehicle. .

  The tread pattern described in Patent Document 1 is provided with a wide rib sandwiched between two wide circumferential grooves in the center portion, and block rows are arranged on the outer and inner shoulder portions. The lateral groove extends to the rib at the central portion to improve drainage.

However, when such a tread pattern is mounted on a vehicle provided with a negative camber for improving high-speed driving performance, the tread portion breaks down due to heat generation of the tread portion particularly in a speed range of 270 km / h or more. There is a case. As a countermeasure against heat generation in this tread, it is conceivable to use a low-heat-generating tread compound, but the low-heat-generating tread compound has low grip, making it difficult to ensure steering stability at high speeds. There is a problem of becoming.
JP 2000-238510 A

  An object of the present invention is to provide a pneumatic tire that is mounted on a vehicle provided with a negative camber and that improves high-speed durability while achieving both steering stability and drainage.

  In order to achieve the above object, the pneumatic tire of the present invention is a tire that is mounted on a vehicle provided with a negative camber, with the mounting direction of the tire side being specified, and two tires on the center of the tread surface. Forming a central land portion sandwiched between circumferential grooves, forming a block-shaped land portion partitioned into a number of inclined sub-grooves at an inner end portion of the central land portion, and a rib-shaped land portion at an outer end portion In the pneumatic tire in which a block row is formed on each of the inner shoulder and the outer shoulder, when the inner circumferential groove of the two left and right circumferential grooves is grounded in a state of being mounted on the vehicle, the tire Arranged so as to overlap the region where the circumferential contact length is maximum, and as the inclined sub-groove, the first inclined sub-groove extending from the inner circumferential groove to the middle of the central land portion is intermittent in the tire circumferential direction. Placed The block-shaped land portion is formed by arranging a second inclined sub-groove that intersects with the three or more first inclined sub-grooves adjacent to each other and that does not communicate with any of the two circumferential grooves. It is characterized by doing so.

  The pneumatic tire of the present invention is mounted on a vehicle provided with a negative camber with the inside and outside orientations specified, and the tread surface forms a central land portion sandwiched between two circumferential grooves on the left and right in the central region, In the pneumatic tire in which the block-like land portion is formed at the inner end portion of the central land portion, the rib-like land portion is formed at the outer end portion, and the block rows are formed at the inner and outer shoulders, the left and right two Of the circumferential grooves, the inner circumferential groove is arranged so as to overlap the region where the tire circumferential ground contact length becomes maximum when grounded in a state of being mounted on a vehicle, and therefore, at high speeds, particularly 270 km / h. Even in the above speed range, by reducing the amount of rubber in the region where heat generation should be highest, heat generation of the tread rubber can be suppressed, and in order to suppress deterioration of the tread portion due to the heat generation, high speed resistance It is possible to improve the sex. Moreover, since the inner circumferential grooves are arranged as described above, the hydroplaning resistance can be improved.

  Furthermore, the first inclined sub-groove is formed so as to extend from the inner circumferential groove to the middle of the central land portion so as not to communicate with the outer circumferential groove, and intersects with the second inclined sub-groove at the inner end portion of the central land portion. The block-shaped land portion is formed by the above, and the rib-shaped land portion is formed at the outer end, so that the drainage is improved by the inner block-shaped land portion, and the rigidity of the tread surface is improved by the outer rib-shaped land portion. Therefore, it is possible to ensure steering stability when traveling on a dry road surface.

The present invention is described in detail below.
FIG. 1 is a development view showing an example of a tread pattern of the pneumatic tire of the present invention.

  The pneumatic tire of the present invention is mounted on a vehicle provided with a negative camber. For this reason, when the tire is mounted on the vehicle, the left and right tires have a slightly downward opening relationship when viewed from the front of the vehicle, and the position where the tire is shifted from the equator toward the vehicle is the center of the ground contact width. The angle of the negative camber is generally set in the range of 1 ° to 3 °.

  When the tire of the present invention is mounted on a vehicle, the direction of the side surface is designated. In FIG. 1, the IN side is the vehicle side, that is, the inside, and the OUT side is the outside. An arrow R indicates the direction of rotation when the vehicle moves forward. On the tread surface 1, an inner shoulder block row 24 is disposed on the inner shoulder and an outer shoulder block 25 is disposed on the outer shoulder at both ends in the tire width direction when the vehicle is mounted. Further, circumferential grooves 11, 12, 13 extending in the tire circumferential direction are formed on the tread surface 1. Of these, the two circumferential grooves 11 and 12 are arranged with the tire center line CL in between, and define the central land portion 21. The central land portion 21 has a first inclined sub-groove 14 and a second inclined sub-groove 15 having different inclination directions with respect to the circumferential direction.

  Here, of the two circumferential grooves 11, 12, the inner circumferential groove 11 overlaps with a region where the tire circumferential ground contact length becomes maximum when the tire is grounded in a state where the tire is mounted on the vehicle. Has been placed.

  When the pneumatic tire of the present invention is mounted on a vehicle provided with a negative camber, the inner circumferential groove 11 is arranged so as to overlap the region where the ground contact length in the tire circumferential direction of the tread surface is maximum as described above. Therefore, when the vehicle is traveling at a high speed, particularly in a speed region of 270 km / h or higher, the amount of rubber in the region where the ground contact pressure should be increased can be reduced to suppress heat generation of the tread rubber. Therefore, the high-speed durability can be improved because the deterioration of the tread portion due to the heat generation is suppressed. Moreover, since the inner circumferential groove 11 is arranged as described above, the hydroplaning resistance can be improved.

  The first inclined sub-groove 14 extends from the inner circumferential groove 11 to the middle of the central land portion 21 and is formed so as not to communicate with the outer circumferential groove 12. The second inclined sub-groove 15 is formed in the inner circumferential direction. Instead of communicating with any of the groove 11 and the outer circumferential groove 12, it intersects with three or more adjacent first inclined sub-grooves 14. Thereby, the block row | line | column divided by the inner side circumferential direction groove | channel 11, the 1st inclination subgroove 14, and the 2nd inclination subgroove 15 is formed so that it may straddle a tire center line as the block-shaped land part 22. FIG. Therefore, the central land portion 21 is composed of a block-like land portion 22 formed of a block row and a rib-like land portion 23 continuous in the tire circumferential direction outside the block-like land portion 22.

  In the pneumatic tire of the present invention, the first inclined sub-groove 14 is formed so as to extend from the inner circumferential groove 11 to the middle of the central land portion 21 and not communicate with the outer circumferential groove 12. Since the block-like land portion 22 is formed at the inner end portion of the 21 by the intersection with the second inclined sub-groove 15 and the rib-like land portion 23 is formed at the outer end portion, the inner block-like land portion 22 discharges water. Since the outer rib-like land portion 23 improves the rigidity of the tread surface, it is possible to ensure the handling stability when traveling on a dry road surface.

  The first inclined sub-grooves 14 that define the block land portions 22 are provided intermittently in the tire circumferential direction, and the acute angle narrow angle α formed with the inner circumferential groove 11 is set to 35 ° to 80 °. Preferably, it is more preferably 40 ° to 75 °. When the narrow angle α is less than 35 °, the width of the block-shaped land portion 22 is narrowed, and the rigidity in the circumferential direction is lowered, which tends to adversely affect steering stability and wear resistance. Further, if it exceeds 80 °, the ground contact shape leading edge line of the tire and the first inclined sub-groove periodically coincide with each other, which may cause pattern noise. The narrow angle α is an acute angle side crossing angle formed by the center line of the inner circumferential groove 11 and the center line of the first inclined sub-groove 14.

  Moreover, the 2nd inclination subgroove 15 is a groove | channel where the both ends formed inside the central land part 21 were sealed, and it is not connected with any of the inner side circumferential groove | channel 11 and the outer side circumferential groove | channel 12. . The second inclined subgroove 15 intersects with three or more first inclined subgrooves 14 adjacent to each other to form a block land portion 22. In addition, it is preferable that the block row forming the block-like land portion 22 is only one row and does not extend over two rows. That is, the rigidity of the block-shaped land portion 22 is determined by arranging two or more second inclined sub-grooves 15 so as not to form two or more block rows with respect to the two first inclined sub-grooves 14. Can be suppressed, and can contribute to maintenance of steering stability.

  The narrow angle β on the acute angle side formed by the first inclined sub-groove 14 and the second inclined sub-groove 15 is preferably 35 ° or more, and more preferably 40 ° to 90 °. When the narrow angle α is less than 35 °, the width of the block is narrowed and the rigidity is lowered, which adversely affects steering stability and wear resistance. The narrow angle β is an acute angle crossing angle formed by the center line of the second inclined sub-groove 15 and the center line of the first inclined sub-groove 14.

  In the present invention, the circumferential grooves 11 and 12 are formed to have a wide width in the range of 8 to 17 mm. On the other hand, the width of the first inclined sub-groove 14 and the second inclined sub-groove 15 is preferably 3 to 7 mm, and more preferably 4 to 6 mm. If the width of the second inclined sub-groove 15 is less than 3 mm, the drainage performance in the central land portion 21 is lowered, and the effect of improving the hydroplaning resistance cannot be sufficiently obtained, which is not preferable.

  In the pneumatic tire of the present invention, the inner circumferential groove 11 and the inner shoulder block row 24 may be directly adjacent to each other, but preferably the second circumferential groove 13 is interposed between them as shown in FIG. It is preferable to arrange the block rows 26 or to provide ribs 27 as in the example shown in FIG. The arrangement of the second block row 26 can further improve the drainage performance when traveling on a wet road surface, and the arrangement of the ribs 27 can further improve the steering stability.

  Moreover, it is preferable that the width | variety of the 2nd block row | line | column 26 or the rib 27 is 8 to 20% with respect to a tire ground contact width, and 10 to 20% is more preferable. When the width of the second block row 26 or the rib 27 is less than 8%, the block rigidity of the second block row 26 is lowered, and steering stability and wear resistance may not be sufficiently obtained. If it exceeds 20%, the volume of rubber constituting the second block row 26 is increased and the high-speed durability is lowered, which is not preferable.

  The tire contact width refers to the contact width when a pneumatic tire is mounted on a standard rim, filled with air pressure of 230 kPa, and a load of 75% of the specified maximum load capacity is applied. Here, the standard is determined by an industrial standard effective in an area where the tire is produced or used. For example, it is “JATM Year Book” of the Japan Automobile Tire Association in Japan, “Standards Manual” of The European Tire and Rim Technical Organization in Europe, and The Tire and Rim Assoc in the United States. “Year Book”.

  Further, it is preferable that the secondary grooves of the second block row 26 are formed along the flow of the first inclined secondary grooves 14. This is because, by extending the extending direction of the first inclined sub-groove 14 along the sub-groove of the second block row 26 as described above, the drainage performance when traveling on a wet road surface can be further improved.

  The pneumatic tire of the present invention can be provided with a sipe extending in the width direction in order to improve the ground contact property of the land portion of the tread surface and to secure the edge effect in the tread width direction. The shape of the sipe is not particularly limited, but it is preferable that the sipe is formed in a zigzag manner on the land as shown in FIG. This is because the grip force on the icy and snowy road surface can be improved particularly during use in winter.

  The pneumatic tire of the present invention is not limited to winter use, but can be advantageously used as an all-season tire.

  Install the pneumatic tires of Examples 1 and 2 and Comparative Examples 1 and 2 (tire size 235 / 45R17, air pressure 220/220 kPa) with a negative camber angle of 2 ° on a domestic car with a 2000cc turbo engine. Steering stability performance and hydroplaning performance were evaluated, and high-speed durability performance was evaluated using a high-speed durability tester.

[Maneuvering stability]
The evaluation was performed by a driver's sensory test in circuit driving. The result was expressed as an index with Comparative Example 1 as 100. It shows that steering stability performance is excellent, so that this value is large.

[Hydroplaning resistance]
In a straight hydroplaning test on a wet road surface with a water depth of about 10 mm, the hydroplaning generation speed was measured. The measurement results were expressed as an index with Comparative Example 1 as 100. It shows that hydroplaning performance is excellent, so that this value is large.

[High-speed durability]
A high speed durability test was carried out by applying a camber angle of 2 ° with an indoor drum and increasing the speed by a step change, and a running distance until the tire failed, that is, speed × time was measured. The measurement results were expressed as an index with Comparative Example 1 as 100. It shows that high-speed durability performance is excellent, so that this value is large.

Comparative Example 1
A pneumatic tire having a tread pattern shown in FIG. 4 was produced. In addition, although the display is abbreviate | omitted in FIG. 4, the sipe is formed in the land part. Moreover, when the pneumatic tire of Comparative Example 1 was mounted on the vehicle, it was confirmed that the region where the contact length was maximum was on the central land portion 21 and did not overlap the inner circumferential groove 11.

  The pneumatic tire of Comparative Example 1 was evaluated for steering stability performance, hydroplaning resistance performance and high-speed durability performance.

Examples 1 and 2
A pneumatic tire having the tread pattern shown in FIG. 2 as Example 1 and the tread pattern shown in FIG. 3 as Example 2 was produced. 2 and 3, the display is omitted, but a sipe is formed in the land portion. In addition, when the pneumatic tires of Examples 1 and 2 were mounted on a vehicle, it was confirmed that the region where the ground contact length was the maximum and the inner circumferential groove 11 overlapped.

  The pneumatic tires of Examples 1 and 2 were evaluated for steering stability performance, hydroplaning performance and high-speed durability performance. The obtained evaluation results are shown in Table 1.

Comparative Example 2
In the tread pattern shown in FIG. 2, a pneumatic tire having a tread pattern in which the position of the inner circumferential groove 11 is shifted inward and the center line of the central land portion 21 is changed to coincide with the tire center line CL is manufactured. did.

  The pneumatic tire of Comparative Example 2 was evaluated for steering stability performance, hydroplaning resistance performance and high-speed durability performance. The obtained evaluation results are shown in Table 1.

  As apparent from Table 1, it was recognized that the pneumatic tires of Examples 1 and 2 improved the hydroplaning performance and the high-speed durability performance while substantially maintaining the steering stability as compared with Comparative Example 1. In particular, it was confirmed that Example 2 was particularly excellent in improving the hydroplaning performance and high-speed durability performance.

  On the other hand, it was recognized that the pneumatic tire of Comparative Example 2 was not significantly different from Comparative Example 1.

It is an expanded view which shows the tread pattern of the pneumatic tire which consists of embodiment of this invention. It is an expanded view which shows the tread pattern which concerns on Example 1 of the pneumatic tire of this invention. It is an expanded view which shows the tread pattern which concerns on Example 2 of the pneumatic tire of this invention. It is an expanded view which shows the tread pattern which concerns on the comparative example 1 of the conventional pneumatic tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread surface 11 Inner circumferential groove | channel 12 Outer circumferential groove | channel 13 Circumferential groove | channel 14 1st inclination subgroove 15 2nd inclination subgroove 21 Central land part 22 Block-shaped land part 23 Rib-like land part 24 Inner shoulder block row | line | column 25 Outer side Shoulder block row 26 Second block row 27 Rib CL Tire center line R Tire rotation direction

Claims (6)

A tire that is attached to a vehicle with a negative camber specified with the mounting direction of the tire side face, and a central land portion sandwiched between two circumferential grooves is formed in the central area of the tread surface, A block-like land portion divided into a number of inclined sub-grooves is formed at the inner end portion of the central land portion, a rib-like land portion is formed at the outer end portion, and a block row is formed on each of the inner shoulder and the outer shoulder. In the pneumatic tire that formed
Among the two left and right circumferential grooves, the inner circumferential groove is arranged so as to overlap the region where the tire circumferential ground contact length becomes maximum when grounded in a state of being mounted on a vehicle, The first inclined sub-groove extending from the inner circumferential groove to the middle of the central land portion is intermittently arranged in the tire circumferential direction, intersecting with the three or more first inclined sub-grooves adjacent to each other, A pneumatic tire in which a second inclined sub-groove that does not communicate with any of the two circumferential grooves is disposed to form the block-shaped land portion.   2. The pneumatic tire according to claim 1, wherein a narrow angle α on an acute angle side formed by the first inclined sub-groove with an inner circumferential groove is 35 ° to 80 °.   The pneumatic tire according to claim 1 or 2, wherein a narrow angle β on the acute angle side formed by the first inclined sub-groove and the second inclined sub-groove is 35 ° or more.   The pneumatic tire according to any one of claims 1 to 3, wherein a second block row is disposed between the block-like land portion in the central land portion and the inner shoulder block row.   The pneumatic tire according to any one of claims 1 to 4, wherein a width of the second block row is 8 to 20% of a tire ground contact width.   The pneumatic tire according to any one of claims 1 to 5, wherein the secondary grooves of the second block row are along the flow of the first inclined secondary grooves.

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