JP2005138678A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reconcile wet braking performance with dry braking performance. <P>SOLUTION: At least one of ribs 4A and 4B is disposed in a tire center section Ct. A tire shoulder section Sh1 inside a vehicle when it is mounted to the vehicle is provided with a rib 6 with: grooves having a plurality of narrow grooves 7 of which only one end is opened to a main groove 1 inside the vehicle or a tire side surface; a plurality of block-like land section 8 between adjacent narrow grooves 7; and a narrow land section 9 continuing in the circumferential direction R. A tire shoulder section Sh2 outside the vehicle is provided with: a plurality of lug grooves 10 of which one end is communicated with a main groove 2 outside the vehicle and the other end is opened to a tire side surface; and a plurality of blocks 11 between adjacent lug grooves 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire capable of achieving both braking performance on a dry road surface and a wet road surface.

  Improving braking performance on wet road surfaces in pneumatic tires is important for ensuring vehicle safety and is a permanent issue. For this reason, conventionally, many tire tread design methods have been adopted in which a large number of grooves and sipes are arranged in a pneumatic tire in order to improve drainage and edge effects and improve wet braking performance. For example, as a pneumatic tire employing this type of technique, there is one disclosed in Japanese Patent Application Laid-Open No. 2002-316517.

JP 2002-316517 A

  However, the arrangement of a large number of grooves and sipes as in the above-mentioned conventional example is useful for improving the wet braking performance, but on the other hand, there is a disadvantage that the dry braking performance is reduced. It was. In other words, pattern rigidity such as block rigidity is reduced by arranging a large number of grooves and sipes, and particularly when braking on dry road surfaces, the dry braking performance decreases due to a decrease in the elastic force in the vehicle longitudinal direction (tire circumferential direction). Was happening.

  Therefore, the present invention has an object to provide a pneumatic tire that improves the disadvantages of the conventional example, secures at least the same wet braking performance as the conventional one, and can improve the dry braking performance. .

  In order to achieve the above object, according to the first aspect of the present invention, at least one main groove in the tire circumferential direction is arranged on the inner side and the outer side of the vehicle when the vehicle is mounted on the vehicle. In a pneumatic tire partitioned into an inner tire shoulder portion and an outer tire shoulder portion, at least one rib is provided in the tire center portion, and only one end is provided on the inner tire shoulder portion on the inner side of the vehicle. A grooved rib having a plurality of narrow grooves opened on the main groove or the side surface of the tire, a plurality of block landing portions between the adjacent narrow grooves, and a narrow land portion continuous in the tire circumferential direction. A plurality of lug grooves having one end communicating with the main groove on the vehicle outer side and the other end opened on the tire side surface, and a plurality of bushes between the adjacent lug grooves. Tsu are provided and click.

  In order to achieve the above object, according to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the width of the narrow land portion in the tire shoulder portion on the inner side of the vehicle is set to 2.5 to the tire ground contact width. It is set within the range of 7.5%.

  In order to achieve the above object, according to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the pitch number of the block adjusting portion in the tire shoulder portion on the inner side of the vehicle is set to the outer side of the vehicle. It is set to 0.5 to 0.75 times the pitch number of blocks in the tire shoulder portion.

  In order to achieve the above object, in the invention according to claim 4, in the pneumatic tire according to claim 1, 2 or 3, the width of the main groove inside the vehicle is made larger than the width of the main groove outside the vehicle. It is also wide.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects, only one end of the pneumatic tire communicates with the main groove. A plurality of non-penetrating sipes are provided.

  The pneumatic tire according to the present invention improves drainage by the lug groove on the outer side of the vehicle to ensure wet braking performance, and includes a tire center rib and a grooved rib (narrow land portion) on the inner side of the vehicle. The pattern rigidity in the circumferential direction can be increased and the dry braking performance can be improved.

  Below, the example of the pneumatic tire concerning the present invention is described in detail based on a drawing. The present invention is not limited to the embodiments.

  Example 1 of a pneumatic tire according to the present invention will be described with reference to FIGS.

  In general, a suspension on the front side of a vehicle is set to change in a toe-out direction due to compliance steering during braking. For this reason, the tire at the time of the change has characteristics that the ground contact area inside the vehicle becomes large and the ground contact pressure becomes particularly high at the shoulder portion inside the vehicle. This characteristic is particularly prominent on the dry road surface than on the wet road surface.

  Therefore, the pneumatic tire of the first embodiment pays attention to such characteristics, and has the following pattern configuration to improve the dry braking performance.

  As shown in FIG. 1, the pneumatic tire according to the first embodiment includes main grooves 1 and 2 in the tire circumferential direction R provided on the inner side and the outer side of the vehicle with respect to the tire center CL when mounted on the vehicle. The vehicle is partitioned into a center portion Ct, a tire shoulder portion Sh1 inside the vehicle, and a tire shoulder portion Sh2 outside the vehicle.

  First, the tire center portion Ct is provided with a main groove 3 in the tire circumferential direction R disposed substantially at the position of the tire center CL, and ribs 4A and 4B are provided on both sides of the main groove 3, respectively. Here, each of these ribs 4A, 4B is formed with a plurality of non-penetrating sipes 5 each having only one end communicating with the adjacent main grooves 1, 2, 3.

  Thus, in the present Example 1, since the ribs 4A and 4B are provided in the tire center portion Ct, the pattern rigidity in the tire circumferential direction R is improved, and the dry braking performance can be improved. In particular, in the rib 4A inside the vehicle, the contact pressure becomes higher when the toe-out changes due to the above-described compliance steer, so that the dry braking performance can be effectively improved.

  Moreover, by providing the non-penetrating sipe 5, drainage performance can be improved and wet braking performance can be improved. Here, in order to achieve both wet braking performance and dry braking performance, it is preferable to dispose each non-penetrating sipe 5 at, for example, 100 to 160 locations in the tire circumferential direction R at substantially equal intervals.

  The non-penetrating sipe 5 may not be provided in order to prioritize the improvement of the pattern rigidity of the ribs 4A and 4B, as long as the desired wet braking performance can be ensured by the tire pattern configuration and the compound.

  Next, a grooved rib 6 shown in FIG. 1 is provided in the tire shoulder portion Sh1 inside the vehicle according to the first embodiment. The grooved rib 6 is formed by forming a plurality of fine grooves 7 opened only toward the tire side surface at predetermined intervals on the rib in the tire circumferential direction R. That is, the grooved rib 6 includes a plurality of narrow grooves 7, a plurality of block landing portions 8 between adjacent narrow grooves 7, and a narrow land portion continuous in the tire circumferential direction R on the main groove 1 side. 9.

  Thus, in the pneumatic tire of the first embodiment, the narrow groove 7 is not communicated with the adjacent main groove 1, that is, the narrow land portion 9 is provided, so that the tire circumferential direction in the tire shoulder portion Sh1 is provided. The pattern rigidity of R is improved. For this reason, when a toe-out change due to compliance steer occurs, the contact pressure at the tire shoulder portion Sh1 becomes higher, and the dry braking performance can be improved.

  Here, FIG. 2 shows the contact area S when the pneumatic tire shown in FIG. 1 changes toe-out due to compliance steer. As is apparent from this ground contact area S, it can be seen that there are more grounds on the road surface inside the vehicle than on the outside of the vehicle, and the ground pressure increases.

  In the first embodiment, the narrow land portion 9 is provided on the main groove 1 side. However, the present invention is not necessarily limited to this. For example, the narrow land portion 9 is provided in the middle portion of the grooved rib 6. May be provided. In such a case, a plurality of narrow grooves 7 opened only on the side of the tire are provided on the inner side of the grooved rib 6 sandwiching the narrow land portion 9 as in the first embodiment, while the main grooves are provided on the outer side of the vehicle. A narrow groove 7 communicating with the groove 1 is provided.

  Next, a plurality of lug grooves 10 provided at a predetermined interval in the tire circumferential direction R and a plurality of blocks 11 provided between adjacent lug grooves 10 are provided in the tire shoulder portion Sh2 outside the vehicle according to the first embodiment. And are formed. As described above, the tire shoulder portion Sh2 is provided with the lug groove 10 that communicates with the main groove 2 and opens on the side surface of the tire, so that drainage is improved and wet braking performance can be improved.

  Here, in the first embodiment, the number of pitches in the tire circumferential direction R of the block landing portion 8 inside the vehicle is made smaller than the number of pitches in the tire circumferential direction R of the block 11 outside the vehicle. Yes. That is, the number of block landing portions 8 is made smaller than the number of blocks 11 so that each block landing portion 8 is larger than the block 11. As a result, the block landing portion 8 has a pattern rigidity higher than that of the block 11 and can further improve the dry braking performance.

  As described above, the pneumatic tire of the first embodiment has a pattern configuration that is asymmetrical with respect to the tire center CL. Therefore, the groove area (groove volume) on the left and right sides (inner side and outer side of the vehicle). Since the ratios are different, there is a risk of uneven wear due to the difference in weight between the left and right rubber portions.

  Therefore, in order to prevent the uneven wear, the total area (total volume) of all the grooves inside the vehicle (main groove 1, non-penetrating sipe 5, narrow groove 7) and all the grooves outside the vehicle (main groove 2, The total area (total volume) of the non-penetrating sipe 5 and the lug groove 10) is made substantially the same.

  In the first embodiment, since the groove area (groove volume) of the narrow groove 7 is mainly smaller than the groove area (groove volume) of the lug groove 10, the width of the main groove 1 inside the vehicle is set to the main groove outside the vehicle. The groove area (groove volume) ratio between the inner side and the outer side of the vehicle is made substantially the same.

  Here, in consideration of merchantability (for example, preventing only one of the main grooves 1 and 2 from disappearing at an early stage), the groove depths of the main grooves 1 and 2 are substantially the same.

  Here, various patterns (patterns A to I) are prepared for the pneumatic tire of the first embodiment described above, a comparative test between these and a conventional type pneumatic tire is performed, and dry braking performance, wet braking performance, The uneven wear resistance was confirmed.

  As these various pneumatic tires, tires of the tire size 215 / 60R16 described in the JATMA YEAR BOOK 2003 edition are manufactured, assembled on a standard rim wheel (16 × 7JJ), and used with an air pressure of 210 kPa. . Moreover, about these various pneumatic tires, the tire ground contact width when the maximum load load was 70% was measured.

  First, the conventional type pneumatic tire used in the comparison test has a pattern configuration as shown in FIG.

  Specifically, this conventional type pneumatic tire has main grooves 102 and 103 equivalent to the pneumatic tire having the pattern configuration of the first embodiment described above, and ribs 104A and 104B in which non-penetrating sipes 105 are formed. A lug groove 110 and a block 111 are provided in the tire shoulder portion Sh2 outside the vehicle. Here, in this conventional type of pneumatic tire, the main groove 101 on the inner side of the vehicle has the same width as the main groove 102 on the outer side of the vehicle, and the lug groove 110 equivalent to the outer side of the vehicle is formed on the tire shoulder portion Sh1 on the inner side of the vehicle. And the point from which the block 111 is provided differs from the pneumatic tire which concerns on the present Example 1.

  Next, as shown in the test results of FIG. 3, the patterns A to I of the pneumatic tire of Example 1 are the ratios of the pitch number of the block landing portion 8 inside the vehicle to the pitch number of the block 11 outside the vehicle ( (Pitch ratio = number of pitches in the block landing portion 8 / number of pitches in the block 11), the ratio of the width of the narrow land portion 9 to the tire ground contact width, and the width of the main groove 2 outside the vehicle The width ratios (main groove width ratio = main groove width inside the vehicle / main groove width outside the vehicle) are respectively changed.

  In the dry braking performance test, the vehicle travels on a dry road surface with the pneumatic tire and the distance from the initial speed of 100 km / h to sudden braking and stopping is confirmed. Here, the test result of this test was expressed by the magnitude of the numerical value corresponding to the stop distance of the conventional type as an index “100”. The larger the index, the shorter the stopping distance and the better the dry braking performance.

  Next, the wet braking performance test is a test run on a wet road surface with a water film of 1 mm on a vehicle equipped with the pneumatic tire, and confirming the distance from the initial speed of 100 km / h until sudden braking and stopping. is there. Here, also in the test results of this test, the stop distance of the conventional type is represented by an index “100”, and is represented by the magnitude of the value. Similarly, the larger the index, the shorter the stopping distance and the better the wet braking performance.

  Subsequently, the uneven wear resistance confirmation test is an actual running on a vehicle equipped with the pneumatic tire on a dry road surface, and a difference in groove depth between the tire shoulder portions Sh1 and Sh2 after running 10,000 km is confirmed. . Here, in the test results of this test, the difference in the groove depth of the conventional type is represented by an index “100”, which is expressed by the magnitude of the value. Here, the smaller the index, the worse the uneven wear resistance.

  According to the test results shown in FIG. 3 performed using the pneumatic tire as described above, the pitch ratio is in the range of “0.5 to 0.75”, and the ratio of the narrow land portion 9 to the tire contact width. Is within the range of “2.5% to 7.5%” and the main groove width ratio is within the range of “1.3 to 1.7”. As shown in FIG. 4, it can be seen that the dry braking performance can be improved while maintaining the wet braking performance equal to or higher than that of the conventional type, and the uneven wear resistance can be maintained equivalent to that of the conventional type.

  Here, if the main groove width ratio is out of the range of “1.3 to 1.7”, it may be understood that any performance (particularly wear resistance) is deteriorated. Depending on the pitch ratio and the ratio of the narrow land portion 9, the pitch ratio may be out of the range of “1.3 to 1.7”. Even in such a case, the above performance is not necessarily inferior. In the first place, the width of the main grooves 1 and 2 is changed between the inside and outside of the vehicle, and the groove area (groove volume) ratio between the inside and outside is changed. The reason why they are substantially the same is to avoid uneven wear due to the asymmetrical pattern configuration. From this, it is assumed that the main groove width ratio should be larger than “1”.

  Further, according to the test results, when the pitch ratio is smaller than “0.5”, the wet braking performance is inferior (pattern E), and when larger than “0.75”, the dry braking performance is inferior (pattern F). I understand.

  It can also be seen that when the proportion of the narrow land portion 9 is lower than 2.5%, the dry braking performance is inferior (pattern G), and when it is higher than 7.5%, the wet braking performance is inferior (pattern H).

  It can also be seen that when the main groove width ratio is set to “1” as in the conventional type, the uneven wear resistance is inferior (pattern I).

  From the above, in the pneumatic tire according to the present invention, the pitch ratio is in the range of “0.5 to 0.75”, and the ratio of the narrow land portion 9 is “2.5% to 7.5%. It has been found that it is suitable to achieve both wet performance and dry performance.

  As described above, according to the pneumatic tire of the first embodiment, the wet braking performance is improved by the lug groove 10 in the tire shoulder portion Sh2 outside the vehicle, the non-penetrating sipe 5 in the tire center portion Ct, and the like. The dry braking performance can be improved by the block landing portion 8 and the narrow land portion 9 in the inner tire shoulder portion Sh1, and the ribs 4A and 4B of the tire center portion Ct. Further, by making the groove area (groove volume) ratio of the inner side and the outer side of the vehicle substantially the same, uneven wear due to the left-right asymmetric pattern can be prevented.

  In particular, as described above, if the pitch ratio is in the range of “0.5 to 0.75” and the ratio of the narrow land portion 9 is in the range of “2.5% to 7.5%”. Further, the dry braking performance can be improved while maintaining the wet braking performance at the same level as the conventional one.

  In the first embodiment, the main groove 3 is provided at the position of the tire center CL. However, the main groove 3 is not necessarily provided as long as the three types of performance described above can be ensured. Further, the main grooves 1 and 2 are provided one by one on the inner side and the outer side of the vehicle. However, it is not always necessary to provide one main groove, and a plurality of main grooves may be provided in consideration of drainage and the like.

  As described above, the pneumatic tire according to the present invention is useful for improving wet braking performance and dry braking performance, and particularly suitable for improving dry braking performance while ensuring the same wet braking performance as before. ing.

It is a figure which shows an example of the pattern structure of the pneumatic tire which concerns on this invention. It is a figure which shows the contact area at the time of braking of the pneumatic tire shown in FIG. It is a figure which shows the test result of the dry braking performance test about the pneumatic tire which concerns on this invention, a wet braking performance test, and a partial abrasion resistance confirmation test. It is the figure which compared the dry braking performance and wet braking performance between the conventional type and the pneumatic tire which concerns on this invention. It is a figure which shows the pattern structure of the conventional type pneumatic tire used for the dry braking performance test, the wet braking performance test, and the uneven wear resistance confirmation test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main groove inside vehicle 2 Main groove outside vehicle 3 Main groove 4A, 4B of tire center 5 Non-penetrating sipe 6 Grooved rib 7 Narrow groove 8 Block landing part 9 Narrow land part 10 Lug groove 11 Block R Tire Circumferential direction Ct Tire center portion Sh1 Tire shoulder portion inside vehicle Sh2 Tire shoulder portion outside vehicle

Claims (5)

A main groove in the tire circumferential direction that is arranged at least one on the inside and outside of the vehicle when mounted on the vehicle, and includes a tire center portion, a tire shoulder portion on the inside of the vehicle, and a tire shoulder portion on the outside of the vehicle. A partitioned pneumatic tire,
Providing at least one rib in the tire center portion;
A plurality of narrow grooves having only one end opened in the main groove or the tire side surface inside the vehicle, a plurality of block landing portions between the adjacent narrow grooves, and a tire circumference A grooved rib having a narrow land portion continuous in the direction is provided,
A plurality of lug grooves having one end communicating with the main groove on the vehicle outer side and the other end opened on the tire side surface, and a plurality of blocks between adjacent lug grooves on the tire shoulder portion on the vehicle outer side. A pneumatic tire characterized by being provided.   The pneumatic tire according to claim 1, wherein the width of the narrow land portion in the tire shoulder portion inside the vehicle is set in a range of 2.5 to 7.5% of a tire ground contact width.   2. The pitch number of the block adjusting portion in the tire shoulder portion inside the vehicle is set to 0.5 to 0.75 times the pitch number of the block in the tire shoulder portion outside the vehicle. 2. The pneumatic tire according to 2.   4. The pneumatic tire according to claim 1, wherein the width of the main groove inside the vehicle is wider than the width of the main groove outside the vehicle.   The pneumatic tire according to any one of claims 1 to 4, wherein a plurality of non-penetrating sipes whose one end communicates with the main groove are provided on the rib of the tire center portion.

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