JP2007302112A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire having eccentric abrasion resistance, draining performance, noise reducing performance and operation stability balanced at a high level independently of extension angle of a lateral groove and groove width thereof. <P>SOLUTION: The pneumatic tire is formed with five lines of land parts between several peripheral grooves 2, 3, 4 and 5 continuously provided in the tread circumferential direction and between the peripheral grooves 2, 5 and tread grounding edges e1, e2. Three lines of the land parts are formed as ribs 7, 9 and 10, and these ribs 7, 9 and 10 are provided with several pairs of L-shaped bent grooves 11, 12, 13, 14, 16 and 17 in each cross direction, and the pairs of bent grooves 11, 12, 13, 14, 16 and 17 are structured of base parts 11a, 12a, 13a and 14a extended in the tread cross direction and opened in any one of the peripheral grooves adjacent to each other and bent parts 11b, 12b, 13b and 14b continued to the base parts and extended in the tread circumferential direction at intermediate positions of the rib width w1 and w2, and terminated inside the ribs 7, 9 and 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a pneumatic tire, and more particularly to a passenger car tire that emphasizes comfort, and in particular, has low noise, steering stability on a dry road surface, drainage, and uneven wear resistance at a high level. We propose technologies that can be harmonized.

  For example, as a conventional tire aiming to greatly reduce the air column resonance sound of the tire while sufficiently reducing the drainage performance while ensuring sufficient handling stability on the dry road surface and limit grip characteristics, As described in Patent Document 1, “two or more circumferential grooves continuous in the circumferential direction are provided on the tread surface, and one end of each circumferential groove is open to the circumferential groove, and the other end is A plurality of lateral grooves that allow inclined grooves are formed independently of other circumferential grooves and other lateral grooves that open to the tread grounding edge, which end in the land portion, and each of these lateral grooves and the circumferential grooves is Under the tire posture where the tire is assembled to the applicable rim and filled with the maximum air pressure and the mass corresponding to the maximum load capacity is loaded, the groove width is set so that the groove walls do not contact each other in the ground contact surface, and each lateral groove The An arrangement in which at least one of the lateral grooves is completely included in the ground, and the extension length of each lateral groove portion in which the groove width of the lateral groove is 30% or more of the lateral width of the circumferential groove in the ground plane is defined as follows. ”, A pneumatic tire that is 40% or more of the extension length of the circumferential groove in the contact surface.”

In addition, as a tread pattern that has been widely used in the past, two linear or zigzag circumferential grooves that are adjacent to each other and extend in the circumferential direction of the tread can also be provided with inclined grooves. One or more sipes consisting of a block pattern formed by opening a plurality of lateral grooves, a block defined between the circumferential grooves, and narrow grooves having a groove wall in contact with each other within the ground plane There is a pattern formed.
International Publication No. 04/103737 Pamphlet

  By the way, in such a conventional technique, in order to prevent the occurrence of uneven wear on the land portion, when increasing the angle of the lateral groove with respect to the tread circumferential direction, an increase in pattern noise, a decrease in drainage, etc. On the other hand, when widening the width of the lateral groove to ensure drainage, there is a higher risk of pattern noise increase, steering stability decrease due to land rigidity decrease, etc. It was extremely difficult to harmonize each of the multiple types of performance at a high level.

  Therefore, the present invention is a pneumatic tire in which uneven wear resistance, drainage performance, low noise performance, and steering stability are harmonized at a high level without depending on the extension angle of the lateral groove, the groove width, etc. Provide a tread pattern.

  In the pneumatic tire according to the present invention, a plurality of land rows are defined between a plurality of linear or zigzag circumferential grooves that are continuous in the tread circumferential direction and between the circumferential groove and the tread grounding edge. In this case, at least one land portion row is a rib, and a plurality of pairs of L-shaped bent grooves are formed on the rib in the width direction, and each pair of bent grooves is Each base that extends in the tread width direction and opens in one of the circumferential grooves adjacent to each other, and each base that is continuous with this base, extends in the tread circumferential direction at an intermediate position of the rib width, and ends in the rib It consists of a bent part.

  Here, the “tread grounding edge” is a state where a tire is mounted on an applicable rim and filled with a specified air pressure, and the tire is placed stationary on a flat plate in a vertical posture, and a load corresponding to a specified mass is applied. When added, the side edge of the contact area on the flat plate of the tire shall be said.

In this case, “applicable rim” refers to the rim specified in the following standards according to the tire size, and “specified air pressure” refers to the air pressure specified in accordance with the maximum load capacity in the following standards. The maximum load capacity refers to the maximum mass allowed to be loaded on the tire according to the following standards. The “specified mass” refers to the above maximum load capacity.
The air here can be replaced with an inert gas such as nitrogen gas or the like.

  The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, “THE TIRE AND RIM ASSOCIATION INC. YEAR BOOk” in the United States, and “THE” in Europe. “STANDARDS MANUAL” of European Tire and Rim Technical Organization, and “JATMA YEAR BOOK” of Japan Automobile Tire Association in Japan.

  In addition, here, the “base extending in the tread width direction” includes a base extending obliquely with respect to the tread width direction.

  By the way, it is of course possible that the respective bent portions of the pair of bent grooves can extend in the same direction with respect to the base portion. Preferably, however, these bent portions are mutually connected to the base portion. Extend in the opposite direction.

  Preferably, one of the pair of bent grooves has a base groove width wider than that of the bent portion, and the other bent groove has a width of the bent portion wider than that of the base portion. To do.

  In this case, for each circumferential groove, one or a plurality of bent grooves with a wide groove width at the base portion and bent grooves with a wide groove width at the bent portion are provided in the extending direction of the circumferential groove. However, it is preferable that the width of the groove of each of the bases be wider than that of the bent part and that of the other adjacent one of the bent grooves opened in one circumferential groove. About the bending groove opened to a circumferential groove, the circumferential groove of all those bending parts is made wider than that of a base part.

  Further, preferably, the groove width of the base portion or the bent portion on the narrow side of each of the pair of bent grooves is set within the ground contact surface under the load rolling of the tire, such as a so-called sipe. The width is in contact with each other.

  More preferably, in such a tire, a plurality of pairs of L-shaped bent grooves that form pairs in the width direction are provided in each of a plurality of rows, for example, two rows of ribs.

In the pneumatic tire according to the present invention, it is possible to secure basic performance including drainage necessary for tires with an emphasis on comfort by partitioning one or more land portion rows between a plurality of circumferential grooves. Here, by making at least one row of land portion rows continuous ribs in the circumferential direction, pattern noise can be reduced, and high land portion rigidity can be ensured on the dry road surface. Steering stability can be improved, and in combination with the drainage action of the circumferential groove, excellent steering stability on a wet road surface can be realized.
The quietness of the tire is more effective as the number of rib rows is increased.

  By the way, as in the conventional tire described above, in the land portion partitioned between the circumferential grooves, one end is opened in the circumferential groove and the other end ends in the land portion, or both the circumferential portions completely cross the land portion. When a horizontal groove that opens together with the groove is provided, it is necessary to reduce the rigidity at the center of the width of the land and increase the pattern noise due to the wide width of the horizontal groove to ensure drainage. In the present invention, at least one row of ribs is provided with an L-shaped bent portion that is paired in the width direction and ends at the middle width portion without communicating with each other, thereby reducing the rigidity of the central portion of the rib width. Can be effectively prevented.

  In addition, here, each pair of bent grooves extends in the tread width direction, opens to one of the circumferential grooves adjacent to each other, and continues to the base, and is located at an intermediate position of the rib width. With each bent portion extending in the tread circumferential direction and ending in the rib, the drainage efficiency of the central portion of the rib is increased under the action of the base portion and the bent portion of each bent groove. In addition, the edge component extending in the tread width direction can be increased while securing the rib rigidity in the front-rear direction, and the maneuverability on dry and wet road surfaces can be improved. An increase in pattern noise can be effectively prevented by eliminating the lateral groove from the center of the width of the pattern.

  In addition, the base that opens in the circumferential groove is extended in the tread width direction to promote drainage and excellent braking and driving on dry and wet road surfaces with an increase in the edge component in the tread width direction. Performance can be ensured, and the formation of an L-shaped bent groove can realize excellent drainage efficiency without setting a wide groove width, thus effectively preventing a decrease in rib rigidity. can do.

  In this tire, when the extending direction of the bent portion of the pair of bent grooves is opposite to the base, the rib deforms even if the rotation direction of the tire changes. Since no significant change occurs, unlike the so-called directional pattern, stable motion performance and the like can always be ensured regardless of the mounting posture of the tire on the vehicle.

Also, here, one of the paired bent grooves has a base groove width wider than that of the bent portion, and the other bent groove has a width of the bent portion wider than that of the base portion. When compared with the case where the entire bent groove is a wide groove, the required drainage is ensured, yet it has excellent low noise performance and excellent maneuverability with rib rigidity ensured. Can bring.
In other words, forming the bent grooves in pairs makes it possible to sufficiently increase the drainage efficiency, so that it is not necessary to make the entire bent groove wide, and either the base portion or the bent portion is used. This is because it is sufficient to make only one side wide.

  In addition, by forming the wide and narrow portions in reverse between the pair of bent grooves, in addition to excellent drainage and low noise, regardless of the direction of tire rotation, And high land rigidity can be secured.

By the way, in this case, in the bent groove opening in one circumferential groove, the groove width of all the bases is wider than that of the bent part, and in the bent groove opening in the other adjacent circumferential groove When the groove width of all the bent portions is wider than that of the base portion, the total performance with respect to drainage performance, low noise performance and land portion rigidity can be further enhanced.
That is, when the base portion is wide, there is a concern in terms of noise even if the decrease in land rigidity can be suppressed. On the other hand, when the bent portion is wide, the opposite phenomenon occurs. Therefore, the required performance can be ensured by adopting one of these between the pair of bent grooves.

In the tires as described above, the groove width of the base or bent part, which is the narrow side of each pair of bent grooves, is the width at which the groove walls, such as sipes, contact each other within the ground plane. In this case, the edge component extending in the tread width direction or the tread circumferential direction can be effectively increased in the narrow side portion without substantially reducing the rib rigidity and without increasing the noise. .
In addition, regarding drainage, it can contribute to drainage effectively based on the opening and closing deformation of the narrow groove portion immediately before and after entering the ground plane.

  Furthermore, when multiple pairs of L-shaped bent grooves that are paired in the width direction are provided in each of two or more rows of ribs, in addition to low noise, various performances on dry and wet road surfaces Can be harmonized in a higher dimension.

FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention.
In addition, since the internal reinforcement structure of a tire can be the same as that of a general radial tire for a passenger car, illustration is omitted here.

  Here, in the tread ground surface 1, a linear or zigzag shape in the circumferential direction of the tread, which extends continuously in a straight line shape in the figure, for example, four annular circumferential grooves 2, 3, 4, having different widths from each other, for example. 5 in total, between each of the circumferential grooves, between the circumferential groove 2 and one tread grounding edge e1, and between the circumferential groove 5 and the other tread grounding edge e2, a total of five rows of land In the partial row, in the figure, five rows of ribs 6, 7, 8, 9, 10 are defined.

The “tread contact surface” here refers to a state in which a tire is mounted on an applicable rim and filled with a specified air pressure, and the tire is placed stationary on a flat plate in a vertical posture, and a load corresponding to a specified mass is applied. It shall be the contact area of the tire on the flat plate when added.
In this case, “applicable rim”, “prescribed air pressure”, “prescribed mass” and the like are the same as defined above.

  Also, here, a plurality of pairs of L-shaped bent grooves 11, 12, and 13, 14 are provided in the width direction of the ribs 7, 9, and the respective bent grooves 11, 12, and 13 and 14 extend in the tread width direction and are continuous with the respective base portions 11a, 12a and 13a, 14a which open in one of the circumferential grooves 2, 3 or 4, 5 adjacent to each other, and the tips of the base portions. And the intermediate position that does not reach the center of the rib widths w1 and w2, in other words, the bent portions extending in the tread circumferential direction and ending in the ribs 7 and 9 at the circumferential groove side portion from the central position of the rib width. 11b, 12b and 13b, 14b.

In this figure, since each of the base portions 11a, 12a, 13a, and 14a extends to the left, the respective bent grooves 11, 12, 13, and 14 have the left ascending. Make a pair under the relative relationship.
On the other hand, each base part can be extended substantially in the tread width direction, and can also be extended in a left-down manner.

Preferably, the extending direction of the bent portions 11b, 12b and 13b, 14b is made between the pair of bent grooves 11, 12, and 13, 14 with respect to the base portions 11a, 12a and 13a, 14a. The directions are opposite to each other.
In this case, when considering the drainage point of each bent groove 11, 12, 13, 14 and the point of rigidity of the land portion defined by the bent grooves 11, 12, 13, 14 In relation to the extending form of the base, it is preferable that the angle of intersection between the base and the bent portion continuous thereto is, for example, an obtuse angle as illustrated.

  Further, preferably, in one of the pair of bent grooves 11, 12, and 13, 14, the base portions 11a, 14a have a wider width than that of the bent portions 11b, 14b. On the other hand, in the other bent grooves 12, 13, the groove widths of the bent portions 12b, 13b are made wider than those of the base portions 12a, 13a, and in particular, the wide drainage portion ensures excellent drainage.

  In this case, the wide and narrow portion of the groove width can be reversed between the pair of bent grooves 11, 12, 13 and 14, as shown in FIG. 11 and 12 is applied to the pair of bent grooves 13 and 14 as they are, or conversely, the wide and narrow relatives of the pair of bent grooves 13 and 14 are respectively applied. The relationship can also be applied as it is to each of the pair of bent grooves 11 and 12.

  And preferably, in the bent grooves 11 and 14 opened in one of the circumferential grooves 2 and 5, the groove widths of all the base portions 11a and 14a are wider than those of the bent portions 11b and 14b, and adjacent to each other. In the bent grooves 12 and 13 opened in the other circumferential grooves 3 and 4, the groove widths of all the bent portions 12b and 13b are wider than those of the base portions 12a and 13a.

  Also in this case, the wide and narrow portion of the groove width can be reversed between the pair of bent grooves 11, 12 and 13, 14 as shown in the figure. Also here, the relative relationship between the wide and narrow portions of the pair of bent grooves 13 and 14 is the same as that of the wide and narrow portions of the pair of bent grooves 11 and 12, or conversely, The relative relationship between the wide and narrow portions of the grooves 11 and 12 may be the same as that of the wide and narrow portions of the pair of bent grooves 13 and 14.

  In the pneumatic tire as described above, more preferably, the narrow base portions 12a and 13a or the bent portions 11b and 14b in the respective bent grooves 11, 12, and 13, 14 that make a pair are used for the load rolling of the tire. A narrow groove having a groove width such that the groove walls come into contact with each other in the ground contact surface, for example, a sipe, is formed during the movement, and the rigidity of the ribs 7 and 9 is prevented from becoming too low by this sipe.

  That is, when all the portions of the bent groove are wide, in addition to concern about the deterioration of the maneuverability due to the reduced rigidity of the ribs, the wear resistance is also lowered. By adopting such a narrow groove, it is possible to solve these problems and reduce generated noise. In addition, when all the portions of the bent groove are narrow-width grooves, not only the drainage performance is insufficient, but also the rib rigidity becomes too high, which adversely affects riding comfort.

Further, in the tire shown in this figure, in each rib other than the two rows of ribs 7 and 9 provided with the pair of bent grooves 11, 12 and 13, 14, the rib 8 has the bent grooves 12, 14. A plurality of bent grooves 15 that extend in an L shape under the same extended form as, for example, a sipe as a whole are formed at predetermined intervals in the circumferential direction of the tort. The bent grooves 16, 17 extending in an L-shape and extending in the same shape as the pair of bent grooves 11, 12, or 13, 14 are formed.
Therefore, in the illustrated example, the paired bent grooves 16 and 17 also correspond to the “L-shaped bent grooves paired in the width direction of the rib” in the present invention.

  Further, the rib 6 has an annular sipe 18 that continuously extends linearly in the tread circumferential direction on the circumferential groove 2 side from the center position of the width thereof, and extends to the left in a curved form that protrudes downward in the figure. The curved groove 19 opened to both the circumferential groove 2 and the tread ground edge e1 and the curved groove 19 extending downward from the tread ground edge e1 toward the annular sipe 18 side. An inclined sipe 20 is formed, and the groove width of the curved groove 19 is wide at the opening portion to the tread ground edge e1, and the remaining portion is narrow as in the sipe.

Example 1
In the tread pattern shown in FIG. 1, the respective groove widths from the circumferential groove 2 that is mounted on the vehicle and is located on the outermost side of the vehicle to the circumferential groove 5 that is located on the innermost side are sequentially 10 mm, 6 mm, 12 mm, and 8 mm, and a groove depth of 8.3 mm, and provided in three rows of ribs 7, 9, 10 are bent grooves 11, 12, 13 that are bent in an L shape in pairs. 14, 16 and 17, the tire width of the 235/45 R15 with the groove width of the wide portion being 2 mm and the groove width of the narrow portion being 0.5 mm is mounted on the applicable rim and the air pressure is 230 kPa. And mounted on an actual vehicle, under load conditions equivalent to two passengers, hydroplaning resistance when traveling straight ahead, steering stability on dry and wet road surfaces, tire pattern resistance 'S, the riding comfort and wear resistance were evaluated with a index value. The results shown in Table 1 were obtained.

Here, the hydroplaning resistance during straight running is determined by evaluating the hydroplaning phenomenon generation speed when feeling through a wet road surface having a water depth of 5 mm,
Steering stability on a dry road surface is obtained by evaluating the circuit course in a dry state based on the feeling of a test driver when driving in various driving modes. The circuit course is determined by evaluating the feeling of the test driver when driving in various driving modes,
Tire pattern noise is determined by evaluating the feeling of the test driver when driving in various driving modes on a dry test course.
Riding comfort is determined by evaluating the feeling of the test driver when driving in a dry test course in various driving modes,
And abrasion resistance was calculated | required by measuring the amount of level | step wear between adjacent land part parts or blocks when drive | working 5000 km on the general road of a dry state in various driving modes.
In addition, the index value in a table | surface shall show the better result, so that it is large.
Table 1 also shows the evaluation results of the comparative tire 2 having the tread pattern shown in FIG.

  By the way, in the comparative example tire 1 shown in FIG. 2, the groove depth of the lug groove provided in the shoulder land portion is shallow at the opening end portion to the circumferential groove (see the thin line portion in the figure). In the comparative example tire 2 shown in FIG. 2, the surface height of the land portion is gradually lowered toward the tip of the corner portion forming an acute angle. (See the thin line in the figure)

  According to the results shown in Table 1, it is clear that the example tires show better results than either of the comparative example tires 1 and 2 for any performance.

It is an expanded view of the tread pattern which shows embodiment of this invention. 3 is a development view showing a tread pattern of a comparative tire 1. FIG. 3 is a development view showing a tread pattern of a comparative example tire 2. FIG.

Explanation of symbols

1 tread contact surface 2, 3, 4, 5 circumferential grooves 6, 7, 8, 9 ribs 11 and 12 paired bent grooves 11a, 12a, 13a, 14a base portions 11b, 12b, 13b, 14b bent portions 13, 14 Folding groove 15 which makes a pair Folding groove 16, 17 Folding groove 18 which makes a pair Annular sipe 19 Curved groove 20 Inclined sipe e1, e2 Tread grounding edge w1, w2 Rib width

Claims (6)

In a pneumatic tire formed by dividing a plurality of land rows between a plurality of circumferential grooves continuous in the tread circumferential direction and between the circumferential groove and a tread grounding edge,
At least one land portion row is a rib, and a plurality of pairs of L-shaped bent grooves are provided on the rib in the width direction, and each pair of bent grooves extends in the tread width direction. Each of the bases that open to one of the circumferential grooves adjacent to each other, and each bent part that continues to the base and extends in the tread circumferential direction at an intermediate position of the rib width and ends in the rib. A pneumatic tire made up of.   The pneumatic tire according to claim 1, wherein the extending directions of the bent portions of the pair of bent grooves are opposite to each other with respect to the base portion.   2. The groove width of the base portion is wider than that of the bent portion on one side of the pair of bent grooves, and the groove width of the bent portion is wider than that of the base portion on the other bent groove. Or the pneumatic tire of 2.   In the bent groove that opens in one peripheral groove, the groove width of all the bases is wider than that of the bent part, and in the bent groove that opens in the other peripheral groove, the groove of all the bent parts The pneumatic tire according to any one of claims 1 to 3, wherein the width is wider than that of the base portion.   The pneumatic tire according to claim 3 or 4, wherein the groove width of the narrow base portion or the bent portion of each of the paired bent grooves is a width at which the groove walls contact each other within the ground contact surface.   The pneumatic tire according to any one of claims 1 to 5, wherein a plurality of pairs of L-shaped bent grooves paired in the width direction are provided on each of the plurality of rows of ribs.

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